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22001133
16th Symposium on Thermal Science and Engineering of Serbia
under title:
“Energy – Ecology – Efficiency”
is organized by:
University of Niš, Faculty of Mechanical Engineering in Niš and
Society of Thermal Engineers of Serbia
Under patronage of the
GOVERNMENT OF THE REPUBLIC OF SERBIA MINISTRY OF EDUCATION, SCIENCE AND TECHNOLOGICAL DEVELOPMENT
and supported by:
General Sponsor
SERBIAN CHAMBER OF ENGINEERS, Belgrade
Grand Donor
ENERGOPROJEKT ENTEL, Belgrade
Sponsors and Donors
ŠUKOM, Knjaževac
JUGOTERM, Merošina
HERZ, Belgrade
KGH INŽENJERING, Zaječar
FENIKS BB, Niš
MIKOTERM, Niš
RADING, Kraljevo
TROX TECHNIK, Belgrade
VIA OCEL, Belgrade
RADIJATOR INŽENJERING, Kraljevo
WILO, Belgrade
HENCO, Belgium
YUTKL, Niš
ВладаРепубликеСрбије
Министарствопросвете,наукеитехнолошкогразвоја
Инжењерска комора Србије
ENERGOPROJEKT ENTEL
v
International Scientific Committee Dr. Gligor Kanevče [MK] Dr. Sophia Natalia Boemi [GR]
Dr. Slavtcho G. Slavtchev [BG] Dr. Dušan Golubović [BA]
Dr. Agis M. Papadopoulos [GR] Dr. Petar Gvero [BA]
Dr. Petar Novak [SI] Dr. Maria Ichim [RO]
Dr. Neven Duić [HR] Dr. Vesna Barišić [FI]
Dr. Ljubica Kanevče [MK] Dr. Dečan Ivanović [ME]
Dr. Sašo Medved [SI] Dr. Uroš Karadžić [ME]
Dr. Peter Stankov [BG] Dr. Gyula Gróf [HU]
Dr. Jordan Hristov [BG] Dr. Friedrich Dinkelacker [DE]
Program Committee Prof. Dr. Mladen Stojiljković University of Niš, Faculty of Mechanical Engineering in Niš Prof. Dr. Milan Radovanović University of Belgrade, Faculty of Mechanical Engineering in Belgrade
Prof. Dr. Simeon Oka Vinča Institute, Belgrade Prof. Dr. Miroljub Adžić University of Belgrade, Faculty of Mechanical Engineering in Belgrade Prof. Dr. Gradimir Ilić University of Niš, Faculty of Mechanical Engineering in Niš
Prof. Dr. Bratislav Blagojević University of Niš, Faculty of Mechanical Engineering in Niš Prof. Dr. Dragoljub Živković University of Niš, Faculty of Mechanical Engineering in Niš Prof. Dr. Velimir Stefanović University of Niš, Faculty of Mechanical Engineering in Niš
Prof. Dr. Dragoslava Stojiljković University of Belgrade, Faculty of Mechanical Engineering in Belgrade Dr. Predrag Stefanović Vinča Institute, Belgrade
Prof. Dr. Dragoslav Šumarac University of Belgrade, Faculty of Civil Engineering in Belgrade Dr. Miodrag Mesarović Energoprojekt ENTEL, Belgrade
Prof. Dr. Dušan Gvozdenac University of Novi Sad, Faculty of Technical Sciences Prof. Dr. Milun Babić University of Kragujevac, Faculty of Enginnering Sciences in Kragujevac
Prof. Dr. Vladan Karamarković University of Kragujevac, Faculty of Mechanical and Civil Eng. in Kraljevo Dr. Žarko Stevanović Vinča Institute, Belgrade Prof. Dr. Zoran Stajić University of Niš, Faculty of Electronic Engineering in Niš Prof. Dr. Miloš Banjac University of Belgrade, Faculty of Mechanical Engineering in Belgrade
Prof. Dr. Maja Todorović University of Belgrade, Faculty of Mechanical Engineering in Belgrade Prof. Dr. Goran Jankes University of Belgrade, Faculty of Mechanical Engineering in Belgrade
Honoured Committee Prof. Dr Vlastimir Nikolić, University of Niš, Faculty of Mechanical Engineering in Niš
Prof. Dr. Dragan Antić, University of Niš, Faculty of Electronic Engineering in Niš Prof. Dr. Jovan Stepanović, University of Niš, Faculty of Technology in Leskovac Prof. Dr. Ćemal Dolićanin, State University of Novi Pazar
Prof. Dr. Maja Đurović Petrović, European University, Faculty for International Engineering Management Jaroslav Urošević, Energoprojekt ENTEL
Organizing Committee Doc. Dr. Dejan Mitrović University of Niš, Faculty of Mechanical Engineering in Niš Doc. Dr. Mirjana Laković University of Niš, Faculty of Mechanical Engineering in Niš
Prof. Dr. Branislav Stojanović University of Niš, Faculty of Mechanical Engineering in Niš Prof. Dr. Mića Vukić University of Niš, Faculty of Mechanical Engineering in Niš
Doc. Dr. Jelena Janevski University of Niš, Faculty of Mechanical Engineering in Niš Prof. Dr. Gordana Stefanović University of Niš, Faculty of Mechanical Engineering in Niš
Dr. Goran Vučković University of Niš, Faculty of Mechanical Engineering in Niš Doc. Dr. Predrag Zivković University of Niš, Faculty of Mechanical Engineering in Niš Mr. Dragan Kuštrimović University of Niš, Faculty of Mechanical Engineering in Niš
Mirko Stojiljković University of Niš, Faculty of Mechanical Engineering in Niš Marko Ignjatović University of Niš, Faculty of Mechanical Engineering in Niš
vi
Disclaimer
The contents of the papers presented in this publication are the sole responsibility of their authors and can in no way be taken to reflect the views of the Organizer.
vii
Contents
1. Plenary Session 1
1.01. Upgrade by an Innovative Installation of Additional Economizer at the 620 MWe Lignite‐Fired Power Plant
Vladimir Stevanovic 2
1.02. The Main Strategic Objectives of the Romanian Energy Sector in National and International Context
Maria Ichim 3
1.03. Integral‐balance Method to Transient Heat, Mass and Momentum Transfer of Integer and Fractional Order
Jordan Hristov 4
1.04. Some Controversial Issues on Energy Sustainability Miodrag Mesarović 5
1.05. Ranking Literature Sources for Multidisciplinary Research Miodrag Mesarović 6
2. Technologies and Plants 7
2.01. Design of a bulb turbine stay vane and runner for the small hydro power plant “Grčki mlin’’ near Prokuplje
Božidar Bogdanović, Dragica Milenković, Jasmina Bogdanović‐Jovanović, Živan Spasić 8
2.02. The Use of Preheated Low‐Enriched Air in Downdraft Gasifiers: Energy and Exergy Analysis
Rade Karamarković, Vladan Karamarković, Anđela Lazarević, Miljan Marašević, Nenad Stojić 9
2.03. Energy and exergy analysis of Brayton cycle with working fluid of temperature dependent physical properties
Antun Galović, Marija Živić , Mario Holik, Ružica Končić 10
2.04. Alternative modeling approaches to sulfation reactions of calcium based sorbents injected in the pulverized coal furnace
Ivan D. Tomanović, Srđan V. Belošević, Andrijana D. Stojanović, Dragan R. Tucaković, Titoslav V. Živanović 11
2.05. Energy Consumption of Compressed Air Systems and Potential of Heat Recovery with example
Milovan Medojević, Jovan Petrović 12
viii
2.06. Analysis of dynamic behaviour of hot water boilers during start up Milena Todorović, Dragoljub Živković, Marko Mančić, Dragan Milčić 13
2.07. Technology for manufacturing of turbine parts for micro and mini hydroelectric power plants
Dragan Temeljkovski, Stojanče Nusev, Dragana Temeljkovski 14
2.08. Vertical Limited Fluid Bed for Burning Granulated Bio, Fossil and Waste Fuel in Power Plant Boilers and Conversion of Coal by Biomass
Radislav Vujadinović 15
2.09. Thermal Fatigue of Materials Dušan Petković, Goran Radenković 16
3. New and Renewable Energy Sources 17
3.01. Potential Fire Hazards of Renewable Energy ‐ Horizons of Tomorrow Miloš Banjac, Barbara Vidaković 18
3.02. Possibilities and Directions for Participation of Available RES in Macedonia with Scenarios for Achieving the 20/20/20 Goal of the EC
Mile Dimitrovski 19
3.03. Optical Design of a Solar Parabolic Concentrator Based on Square Flat Facets Saša R. Pavlović, Velimir P. Stefanović, Ivan Stojanović, Suad Suljković, Dragan Kuštrimović 20
3.04. Techno‐economic Analysis of Photovoltaic‐based Stand‐alone Power System for Supply of Metrological Masts’ Equipment
Saša Stojković, Vukman Bakić 21
3.05. Solar Drying of Fruits and Vegetables Filip Mojsovski 22
3.06. Comparative Analysis Between Two Methods for Temperature Measurement of PV panels Uglješa Jovanović, Igor Jovanović, Zoran Petrušić, Dragan Mančić 23
3.07. Technical and Economic Analysis of Hybrid Wind‐photovoltaic Power System for Supply of Meteorological Masts’ Measuring Equipment
Saša Stojković, Vukman Bakić 24
3.08. Technical Feasibility and Financial Analysis of Hybrid Wind‐photovoltaic System for Supply of One Educational Institution
Saša Stojković, Snežana Dragićević 25
3.09. Current State Wind Energy Utilisation in the Republic of Macedonia Monika Lutovska, Vladimir Mijakovski, Cvete Dimitrieska, Vangelče Mitrevski 26
3.10. Agricultural biomass utilization for energy purposes Dejan Đurović, Branislav Repić, Dragoljub Dakić, Aleksandar Erić, Stevan Nemoda 27
3.11. Biogas – Overview of the Possibilities for Implementation in the Macedonian Agricultural Sector
Dame Dimitrovski, Mile Dimitrovski, Gordana Popsimonova, Done Tashevski 28
3.12. Utilization of crude glycerol for the production of biofuels Bojana Danilović, Dragiša Savić, Vlada Veljković 29
ix
3.13. Renewable energy potential in the Rusanda rehabilitation center Milana Perić, Milovan Medojević 30
3.14. Guide Vane Position Control of the Mini Hydro Power Plant by Digital Sliding Mode with Additional Integral Action
Vladislav Blagojević, Miodrag Stojiljković, Živan Spasić 31
3.15. Recent Progress in Biomass Pyrolysis/Gasification Technologies Velimir Stefanović, Andrijana Stojanović, Saša Pavlović 32
4. Mathematical Modeling and Numerical Simulation 33
4.01. Dimensioning of Underground Vertical Heat Exchangers for Geothermal Heat Pump Miloš Banjac, Zara Komnenić 34
4.02. Heat exchangers comparation Kire Popovski, Igor Andeevski 35
4.03. Modeling Thermal Processes Using Bond Graphs Gordana Janevska 36
4.04. Referent Wind Speed and Turbulence Intensity Estimation and on‐Site Wind Turbines Classification
Žarko Stevanović, Nikola Mirkov, Žana Stevanović, Borislav Grubor, Maja Đurović‐Petrović 37
4.05. Wind Load Modeling and Structural Response of Guyed Mast Vukman Bakić, Milada Pezo, Gordana Kastratović, Nenad Vidanović 38
4.06. Numerical Investigation of Thermal Processes in Shell and Tube Heat Exchanger Mića Vukić, Predrag Živković, Mladen Tomić, Ivan Stojanović 39
4.07. CFD Analysis of Forced Convection Heat Transfer Cu‐Water Nanofluids in Circular Tube Kamil Arslan 40
4.08. Flow Simulation and Noise Prediction in Axial Fans Altin Dorri 41
4.09. Numerical Investigation of the Influence of Tip Clearance on Reversible Axial Fan Characteristics
Živan Spasić, Božidar Bogdanović, Vladislav Blagojević, Jasmina Bogdanović‐Jovanović 42
4.10. Review of Critical Heat Flux Predictions
Andrijana Stojanović, Vladimir Stevanović, Dragoljub Živković, Milada Pezo, Ivan Tomanović 43
4.11. Determination of centrifugal pump operating parameters in turbine operating regime Živojin Stamenković, Jasmina Bogdanović‐Jovanović, Jelena Manojlović 44
4.12. Euler‐Euler Granular Flow Model Applied on Numerical Simulation of Liquid Fuels Combustion in a Fluidized Bed
Stevan Đ. Nemoda, Milica R. Mladenović, Dragoljub V. Dakić, Mirko S. Komatina, Aleksandar M. Erić, Milijana J. Paprika 45
4.13. A Parametric Study on Correlations for Transport Parameters in Fixed Bed Regenerators Milan Đorđević, Šefik Bajmak, Marko Mančić 46
4.14. Numerical Prediction of Drag Coefficient for Lattice Structures Milada Pezo ,Vukman Bakić, Gordana Kastratović, Nenad Vidanović 47
x
4.15. Comparison between the energy integration of processes for 1G/2G ethanol production and bioelectricity
Cássia M. Oliveira, Antonio J. G. Cruz, Caliane B. B. Costa 48
4.16. Mathematical models for evaluating evaporation rates from free water surface of indoor swimming pools
Marko Mančić, Dragoljub Živković, Jelena Manojlović, Milena Todorović 49
4.17. Software for Testing the Heat Transfer and Pressure Drop in Vertical Thermosiphon Reboiler
Sonja Stefanov, Dragan Skobalj 50
4.18. Numerical Simulation of Friction Stir Welding Miroslav Mijajlović, Dragan Milčić, Miodrag Milčić 51
5. Experimental Investigation of Processes 53
5.01. Experimental Plant for Testing of Agricultural Biomass Combustion
Zoran Čepić, Biljana Miljković, Branka Nakomčić‐Smaragdakis, Nevena Šenk, Dušan Marković 54
5.02. Investigation of Wood Chips Combustion in Experimental Combustion Chamber Branislav Stojanović, Jelena Janevski 55
5.03. Experimental and Numerical Study of Biomass Combustion in 50 kW Cigar Furnace
Aleksandar M. Erić, Stevan Đ. Nemoda, Dragoljub V. Dakić, Mirko S. Komatina, Branislav S. Repić 56
5.04. Experimental and numerical research of thermal processes in the TST tanks with thermal oil and a phase change medium
Goran Živković, Nedžad Rudonja, Mirko Komatina, Branislav Repić 57
5.05. Determining the Theoretical Reliability Functions of the Thermal Power Systems in Power Plant "Nikola Tesla A"
Dragan Kalaba, Milan Đorđević, Dušan Adamović 58
5.06. An Experimental Research of Effects of Adding a Supplementary Component Generated by a Catalytic Reactor on the Combustion of the Primary Fuel at Internal Combustion Engines
Miloš Milošević, Jovica Pešić, Boban Nikolić, Miodrag Milenković 59
5.07. Experimental investigation of flow‐thermal and operating properties of adsorption filter prototype under climate
Miomir Raos, Ljiljana Živković, Nenad Živković, Jasmina Radosavljević, Milena Jovanović 60
6. Energy Efficiency in Industry, Civil Engineering, Communal Systems and Traffic 61
6.01. Survey of Potential Energy Savings in the Building Sector in Serbia and Needed Investments Maja N. Todorović, Dragoslav M. Šumarac, Radoslav D. Galić 62
6.02. Heat pump application for hot water production in a hotel Sofia‐Natalia Boemi, Elli Kyriaki, Thomas Aslanidis, Agis M. Papadopoulos 63
6.03. Possibilities of applying heta lower temperatures level for heating by using two‐stage heat pump
Šefik M. Bajmak, Milan Đorđević 64
xi
6.04. Analysis of the possibilities of using geothermal heat pumps in the heating and cooling systems with special emphasis spa Ilidža in Peć
Šefik M.Bajmak 65
6.05. Usage of Low‐temperature Energy from the Cooling Tower by applying Cascade Heat Pumps
Vladimir I. Mijakovski, Vangelče B. Mitrevski 66
6.06. Refurbishment of Residential Buildings According to Regulation and Policy Vladimir Jovanovic, Karin Stieldorf 67
6.07. Impact of Insulation on School Building Energy Consumption Snezana Dragićević, Sasa Stojkovic 68
6.08. Determining important factors for improving the energy efficiency, optimal economic and ecological characteristics of a building
Biserka Marković, Vlada Nikolić, Milica Stojanović, Olivera Nikolić, Vuk Milošević, Stevan Marković 69
6.09. Building Facade with Temperature Barrier in Context of Increasing Building Energy Efficiency
Branislav Stojanović, Jelena Janevski, Milica Stojanović, Marko Ignjatović 70
6.10. Energy efficiency of thermal power plant depending on the hydraulic load of cooling tower Mirjana Laković, Milica Jović, Slobodan Mitrović 71
6.11. Endogenous and Exogenous Exergy Destruction and Exergoeconomic Evaluation of Thermal Processes in a Complex Industrial Plant
Goran Vučković, Mirko M. Stojiljković, Gradimir Ilić, Mića Vukić, Miloš Simonović 72
6.12. Introducing curricula of energy efficiency and renewable energy sources by TEMPUS project ENERESE
Ćemal Dolićanin, Bojan Kovačić, Edin Dolićanin 73
6.13. Energy efficiency increasing of indoor swimming pools using solar technology
Dragoljub Živković, Marko Mančić, Peđa Milosavljević, Milena Todorović, Dobrica Pejović, Bojan Stanković 74
6.14. Energy Efficiency Measures Implemented through Projects in Serbia Dragan Pavlović, Pedja Milosavljević, Andjela Lazarević 75
6.15. Calibrating Building Energy Models – “FBB” Building Case Study Bratislav Blagojević, Marko Ignjatović 76
6.16. Energy Efficiency of an Elementary School “Prva Vojvođanska Brigada” Dušan Savić 77
6.17. Energy‐Efficient Technologies Applied in Zero Energy Buildings Suad Suljković, Velimir Stefanović, Saša Pavlović, Ivan Stojanović 78
6.18. Analysis of the Natural Lighting and Energy Demand in the Student Dormitory in Terms of Architectural Design
Petar Pejić, Dušan Petković, Marko Ignjatović, Sonja Krasić 79
6.19. Principles of design and construction of passive houses Sanja Spasić 80
xii
6.20. Application of passive solar systems in architecture Sanja Spasić 81
7. Expert Systems 83
7.01. Governance of energy transition of non‐residental buildings by policy intervention Miroslav Kljajić, Dušan Gvozdenac, Jovan Petrović, Aleksandar Andjelković 84
7.02. Energy systems and their use in public sector in Autonomus Province of Vojvodina Igor Mujan, Aleksandar Anđelković, Jovan Petrović , Miroslav Kljajić 85
7.03. Risk Analysis Methods for Small Hydro Power Plants in Creating Insurance Policy Andjela Lazarevic, Rade Karamarkovic, Vladan Karamarkovic, Dragoljub Lazarevic 86
7.04. Optimization of Trigeneration Systems: A Combinatorial Metaheuristic Approach Mirko M. Stojiljković, Mladen M. Stojiljković, Bratislav D. Blagojević 87
7.05. Cogeneration and Heat Storage in Optimized District Heating Plants. Impact on Heat Costs and Primary Energy Consumption
Mirko M. Stojiljković, Goran D. Vučković, Dejan M. Mitrović 88
7.06. Particle Swarm Optimization for the optimal tilt angle of solar collectors Emina Petrović, Milica Jović, Vlastimir Nikolić, Dejan Mitrović, Mirjana Laković 89
7.07. Intelligent contemporary heating control of an amphitheatre Žarko Ćojbašić, Milan Ristanović, Vlastimir Nikolić, Slavica Stojiljković, Nemanja Marković 90
7.08. Intelligent Control System for Thermal Vision‐Based Person‐Following Robot Platform Ivan Ćirić, Žarko Ćojbašić, Vlastimir Nikolić, Tomislav Igić 91
7.09. Classification of Mobile Objects According to Shape and Size by Applying the Technique of Digital Image Processing
Aca Micić, Biljana Đorđević, Boban Andjelković 92
7.10. Non‐linear contrast image enhancement Biljana Djordjević, Boban Andjelković 93
8. Fluid Flow, Heat and Mass Transfer, and Combustion 95
8.01. Protective Measures Against Water Hammer in a Long Pipeline Hydropower Plant with Pelton Turbine
Dragica Milenković, Dragan Svrkota, Milica Nikodijević 96
8.02. Flow and Heat Transfer of Three Immiscible Fluids in the Presence of Uniform Magnetic Field
Dragiša Nikodijević, Živojin Stamenković, Miloš Kocić, Milica Nikodijević 97
8.03. Influence of Water in Liquid Fuel on the Combustion Stability in Fluidized Bed
Milica R. Mladenović, Stevan Đ. Nemoda, Dragoljub V. Dakić, Milijana J. Paprika, Ana D. Marinković, Branislav S. Repić, Mirko S. Komatina 98
8.04. Influence of Burner Operating Parameters and Fuel Properties On Pulverized Fuel Combustion
Branislav Repić, Dejan Djurović, Ana Marinković, Aleksandar Erić, Goran Živković, Milica Mladenović 99
xiii
8.05. Combustion Experiments with Granular Biomass in a Fluidized Bed Facility
Milica R. Mladenović, Stevan Đ. Nemoda, Dragoljub V.Dakić, Milijana J. Paprika, Dejan M. Đurović, Branislav S. Repić, Srđan B. Uzelac 100
8.06. Determination of a heat transfer coefficient for the back surface of a perforated plate Mladen Tomić, Predrag Živković, Anica Milošević, Biljana Milutinović, Petar Đekić 101
8.07. Determination of a perforated plate convective heat transfer coefficient for wide range of Prandtl numbers
Mladen Tomić, Mića Vukić, Predrag Živković, Gradimir Ilić 102
8.08. Research of Effectiveness of HHO Production for Use in Internal Combustion Engines Miodrag Milenković, Miloš Milošević, Dušan Stamenković, Milan Pavlović 103
8.09. Long‐wavelength Marangoni instability in a binary mixture layer with nonlinear Soret effect
Slavtcho Slavtchev, Penka Kalitzova‐Kurteva, Alex Oron 104
8.10. Analysis of thermodynamic parameters in the injection mold with metal inserts Saša Ranđelović, Saša Nikolić, Mladomir Milutinović 105
9. Environmental Protection 107
9.01. Carbon Dioxide Emission from TPP Nikola Tesla A and B units
Zoran Marković, Milić Erić, Dejan Cvetinović, Predrag Stefanović, Vuk Spasojević , Predrag Skobalj 108
9.02. Reduction of Particulate Matter Emission of the Upgraded Electrostatic Precipitators at Unit B2 of the TPP “Nikola Tesla”
Milić Erić, Predrag Stefanović, Zoran Marković, Predrag Škobalj, Nikola Živković, Vuk Spasojević, Dejan Cvetinović 109
9.03. Indoor air parameters measurements in kindergartens located in different urban environments
Ivan Lazović, Sandra Stefanović, Žana Stevanović, Marija Živković, Maja Đurović‐Petrović, Žarko Stevanović 110
9.04. The Environmental Indicators Related to Indoor Air Quality in Schools Valentina Turanjanin, Biljana Vučićević, Marina Jovanović, Sandra Stefanović 111
9.05. Indoor Air Pollution Modeling of Belgrade Typical Dwelling
Sandra Stefanović, Marija Živković, Ivan Lazović, Žana Stevanović, Maja Đurović‐Petrović, Borislav Grubor, Žarko Stevanović 112
9.06. AHP method for waste treatments ranking in terms of impact on the environment Biljana Milutinović, Gordana Stefanović, Goran Vučković, Mladen Tomić, Petar Djekić 113
9.07. Effective and Environmental Parameters of Diesel Engines Using Biodiesel and Biodiesel – Petro Diesel Blends
Dame Dimitrovski 114
1. Plenary Session
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
2
Upgrade by an Innovative Installation of Additional Economizer
at the 620 MWe Lignite-Fired Power Plant
Vladimir Stevanovic
Abstract: Increase of energy efficiency and power upgrade was achieved at the Unit B1 of the 620 MWe
lignite‐fired Thermal Power Plant “Nikola Tesla B” by the installation of an additional economizer. A new
type of connection of the additional economizer with existing economizer sections was applied, which
enables the utilization of more than 30 MWth of the flue gas waste heat and the increase of the Unit gross
efficiency by 0.53 percentage points, which leads to 9.0 MWe of the electric power production. In
addition, the applied parallel connection of the additional economizer with the first section of the
originally existing economizer leads to the partial feedwater bypass of the high pressure heaters, which
enables an increase of the plant electric power up to 30 MWe. The accompanying effects are the
reduction of the pressure drop in the feedwater line and the economizers, which leads to the decrease of
the energy consumption for the main feedwater pump operation. Also, the change of the feedwater flow
through the additional economizer leads to the change of the turbine power; hence, this effect enables
the utilization of the thermal power plant for the primary control of the electric power system. The
applied technical solution is presented together with the measured and calculated energy effects.
Keywords: waste heat, flue gas, economizer, boiler.
Corresponding author: Vladimir Stevanovic, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
3
The Main Strategic Objectives of the Romanian Energy Sector in
National and International Context
Maria Ichim
Abstract: This paper shows that the main strategic objectives of Romania's energy. Our symposium theme
with reference to energy efficiency and ecological objectives fit very well in EU Directive on energy
efficiency nr.27/2012.
Energy efficiency is a central element of the EU strategy Europe 2020 is a very important strategy for
European countries for smart, sustainable and inclusive growth and the transition to an economy in which
resources are used efficiently and ecologically.
In all this energy objectives contained in the Commission's communication "Energy 2020" represents a key
step in achieving long‐term EU countries in energy and climate.
Keywords: energy efficiency, ecology, resources, renewable energy.
Corresponding author: Maria Ichim, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
4
Integral-balance Method to Transient Heat, Mass and Momentum Transfer
of Integer and Fractional Order
Jordan Hristov
Abstract: The communication collates results on approximate solutions of evolution equations involving
integer order derivatives (parabolic equations) and fractional‐time derivative of Riemann‐Liouville. The
example encompasses transient heat conduction, subdiffusion equations, and transient flows of
viscoelastic fluids and transient diffusion of mass with non‐local integral conditions. The approximate
solutions are in closed forms and allow seeing clearly the controlling parameter; in case of fractional
order the retarding effect of the fading memory. Additional example demonstrating the method with a
heat conduction equation with fading memory based on the Jeffrey’s kernel demonstrates that the final
approximate solution clearly distinguishes the long‐time and the rapidly decaying memory effects in the
heat diffusion.
Keywords: Integral‐balance method; heat conduction, Subdiffusion; Viscoelastic fluid; Memory kernel;
Approximate solution.
Corresponding author: Jordan Hristov, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
5
Some Controversial Issues on Energy Sustainability
Miodrag Mesarović
Abstract: Energy sustainability is a long exploited issue by many organizations and individuals worldwide.
The notions of sustainability, its real meaning, frameworks, goals and even philosophical background are
very often misunderstood, misused or neglected. To achieve sustainability goals in energy field proves to
be a very difficult task in many parts of the world, particularly as different indigenous energy sources are
to be addressed, so that a few countries only are close to achieve it. The World Energy Council (WEC), a
UN accredited international organization, celebrating 90th anniversary this year, keeps energy
sustainability in its logo in an effort to ensure “sustainable energy supply for the greatest benefit of all”.
Here the major messages of WEC on the energy sustainability are incorporated into a review of numerous
controversies present in today’s energy and climate policy, and elsewhere.
Keywords: Energy sustainability index, climate change, renewable energy, energy “trilemma”.
Corresponding author: Miodrag Mesarović, e‐mail: mmesarovic@ep‐entel.com
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
6
Ranking Literature Sources for Multidisciplinary Research
Miodrag Mesarović
Abstract: Multidisciplinary research often proves to be a very difficult task, particularly as different
literature sources are to be addressed. Researchers in thermal science and engineering have at their
disposal different methods which guide them towards the higher ranked academic journals. However,
there are quite noticeable differences in ranks of journals in different academic fields even when the same
ranking method is applied. There are different quantitative ranking indicators, ranging from simple and
easy to calculate (Journal Impact Factor ‐ JIF), to rather complex ones, that employ iterative calculation
procedure (Scimago Journal Ranking ‐ SJR). Here the major ranking indicators for a sample of 40 journals
are presented and compared, including their mutual statistical correlation tests.
Keywords: Citation index, journal impact factor, journal ranking indicator, correlation tests.
Corresponding author: Miodrag Mesarović, e‐mail: mmesarovic@ep‐entel.com
2. Technologies and Plants
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
8
Design of a bulb turbine stay vane and runner for the small hydro power plant
“Grčki mlin’’ near Prokuplje
Božidar Bogdanović, Dragica Milenković, Jasmina Bogdanović-Jovanović, Živan Spasić
Abstract: Turbine stay vane (SV) and runner blades (TR), of existed bulb turbine in a small hydro power
plant “Grcki mlin” near the town Prokuplje, are produced from the plane steel panels with the same
profile inclination angle for all flow surfaces. Such blade shape causes small turbine efficiency (=0.56). By designing new SV and TR, keeping the basic dimensions of the turbine (as owner’s requirement), the
power of the bulb turbine can be increased for approximately 34% (from the current 19.2 kW to 25.8 kW).
As is shown in the paper, to design a new SV and a new TR, it should be increased turbine number of
revolution, from the current 278 rpm to 400 rpm. It can be achieved only by replacing one belt pulley
(weather on the turbine shaft or on the generator shaft). The hydraulic calculation of profile cascades in
elementary stages of turbine is presented in the paper, and here is explained the basic principles of stay
vanes and runner blades modeling. Runner blades are modeled according to blade profiles obtained in 9
chosen flow surfaces. For modeling of turbine stay vanes, profiles obtained in 7 chosen flow surfaces are
used. The paper is illustrated with characteristic drawings, as a part of technical documentations in the
production of turbine stay vanes and runner blades.
Keywords: Small hydropower plant (SHP), bulb turbine, runner blade, stay vane.
Corresponding author: Božidar Bogdanović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
9
The Use of Preheated Low-Enriched Air in Downdraft Gasifiers:
Energy and Exergy Analysis
Rade Karamarković, Vladan Karamarković, Anđela Lazarević, Miljan Marašević, Nenad Stojić
Abstract: In comparison with air, the use of oxygen as a gasifying agent is less exergetically efficient. For
small‐scale cogeneration plants, smaller than 1MW of thermal power, the use of oxygen is expensive and
inefficient. The improvement in the technology of membrane separation of gases gives rise to the possible
inclusion of oxygen‐enriched air as a gasifying medium. The article aims at presenting a numerical study
analyzing the gasification of treated wood in downdraft gasifiers with preheated low‐enriched air (from 21
vol% to 30 vol%). The analyzed system consists of three subsystems: (i) for air enrichment by polymeric
membrane, (ii) for preheating of enriched air by heat exchange with the product gas, and (iii) a downdraft
gasifier. The increase of oxygen level in enriched air increases the temperature at the carbon boundary
point (optimal gasification point), the amounts of combustible gases in the product gas, energy and exergy
efficiencies and decreases the amount of air (oxygen) required for complete gasification as well as the
amount of N2 in the product gas. The preheating of enriched air by heat exchange with the product gas is
more beneficial for the gasification with lower levels of enrichment.
Keywords: Biomass gasification, Exergy analysis, Medium preheating, Oxygen enrichment, Treated wood.
Corresponding author: Rade Karamarković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
10
Energy and exergy analysis of Brayton cycle with working fluid
of temperature dependent physical properties
Antun Galović, Marija Živić, Mario Holik, Ružica Končić
Abstract: In this paper, energy and entropy analysis of Brayton cycle with ideal gas of constant physical
properties and with flue gases of temperature dependent physical properties is given. The cycles are
analyzed in dependence of the pressure ratio p2/p1 and the ratio (T3/T1) of turbine inlet temperature T3
and the compressor inlet temperature T1. Irreversibility of the adiabatic processes in the turbine and
compressor is taken into account using the values of the isentropic efficiencies comp = 0.88 and turb =
0.92. In the adiabatic combustion chamber, methane completely burns by a factor of excess air, which is
determined by the temperature of flue gases on the turbine inlet. All relevant expressions are given in an
analytical form, and results are shown in diagrams and interpreted for the values of pressure ratio1.0 p2/p1 22.0 and the values of the temperature ratio T3/T1 = 3.0; 4.0 and 5.0. We studied the lower and
higher the pressure ratios and the temperature ratios than those that occur in the real performances of
the device, with the aim of quantifying the influence of the variables on borderline values of an amount of
the net work per cycle, the thermal efficiency and the entropy change of the overall system.
Keywords: Brayton cycle, temperature dependent physical properties, net work per cycle, thermal
efficiency.
Corresponding author: Marija Živić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
11
Alternative modeling approaches to sulfation reactions of
calcium based sorbents injected in the pulverized coal furnace
Ivan D. Tomanović, Srđan V. Belošević, Andrijana D. Stojanović,
Dragan R. Tucaković, Titoslav V. Živanović
Abstract: Past researches of desulfurisation by direct furnace sorbent injection of pulverized sorbent into
pulverized coal‐fired boiler furnaces resulted in development of a number of mathematical models.
Reaction mechanism of sulfur reduction by injection of calcium based sorbent can be simulated by use of
different models, varying in complexity, precision and use of computational resources. In this paper,
different approaches to modeling complex calcination‐sintering‐sulfation reactions are analyzed, like
shrinking unreacted core models, grain models and pore models. In addition, we compare Borgwardt’s
semi‐empirical approach (shrinking unreacted core model) with partially sintered spheres model
(belonging to the group of grain models). Borgwardt’s model uses simplified chemical kinetics, resulting in
need for alteration of reaction parameters for each change of sorbent parameters or particle size. The
partially sintered spheres model is more complex and it requires some physical and structural parameters
of sorbent to be known. Its capability to simulate reactions of wide range of different particles and
sorbents makes it more versatile, because it simulates processes in grain, and takes into account different
particle reactant distribution and kinetics. Possibility of application of both models is evaluated, with their
advantages and limitations emphasized.
Keywords: desulfurisation, calcium, sorbent, furnace injection, modeling.
Corresponding author: Ivan D. Tomanović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
12
Energy Consumption of Compressed Air Systems and
Potential of Heat Recovery with example
Milovan Medojević, Jovan Petrović
Abstract: Compressed air is one of the most important utilities for industry. It is also one of the largest
consumers of energy. Therefore, any savings made in compressed air systems have a significant impact on
costs and on the environment. While compressed air systems in general account for about 10% of total
industrial electricity consumption, this can amount to as much as 40% of the electricity bill for certain
plants. In view of this, the aim of this paper is to point out the possibilities for smart compressed air
utilization and measures to increase energy efficiency, potential energy savings in compressed air systems
in Serbia will be shown, while the special emphasis is devoted to heat recovery from air compressors. In
addition to previously mentioned, a method for quick assessment of available heat will be shown, as well
as small techno‐economic analyses.
Keywords: Compressed Air, Energy Consumption, Heat recovery.
Corresponding author: Milovan Medojević, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
13
Analysis of dynamic behaviour of hot water boilers during start up
Milena Todorović, Dragoljub Živković, Marko Mančić, Dragan Milčić
Abstract: Hot water boilers, as the most commonly used central units in district heating system, require
further analysis of reliability, safety and efficiency. Considerable exploitation experience and former
development have indicated new demands and possibilities of using hot water boilers, both in the
municipal heating plants and in the process industry. Today, it is not only expected to have efficient
operation in terms of energy efficiency of primary fuel, but also there are many strict requirements when
it comes to cost‐effective, reliable and safe operation. This paper presents mathematical ‐ empirical model
of a hot water boiler manufactured by “Minel – Kotlogradnja”. The dynamic behaviour of the object will
be discusses in start up regime, as one of the most critical transient regimes.
Keywords: Dynamic Behaviour, Hot Water Boiler, Start up, Transitional Operating Modes.
Corresponding author: Milena Todorović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
14
Technology for manufacturing of turbine parts for
micro and mini hydroelectric power plants
Dragan Temeljkovski, Stojanče Nusev, Dragana Temeljkovski
Abstract: Turbine parts of micro and mini hydroelectric power plants can be manufactured using:
conventional casting, structure‐directed casting, and single crystal casting. The paper presents the above
technologies with an insight into the welding specificities of corrosion‐resistant steels. The examples of
acquired parts of turbine blades produced by domestic manufacturers are also presented. The
evaporative‐pattern casting method provides for objects of very complex shapes with excess material for
surface finishing of 0.3 to 2 mm, high casting hardness, surface quality with average surface roughness
from 0.4 to 6.0 m Ra, with the achieved measurement tolerance of 0.1 mm to 0.5 mm. Apart from
these advantages, the basic characteristics of the process are: high productivity, high usage of materials,
successful application in both small and large‐scale serial production, low tool and equipment costs, and
low reworking.
Keywords: Manufacturing technology, Evaporative‐pattern casting, Control device blades, Mini and micro
hydroelectric power plants.
Corresponding author: Dragan Temeljkovski, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
15
Vertical Limited Fluid Bed for Burning Granulated Bio, Fossil and Waste Fuel
in Power Plant Boilers and Conversion of Coal by Biomass
Radislav Vujadinović
Abstract: In this work is presented invented Vertical Limited Fluid Bed (VLFB) combustion systems
intended for burning granulated 3‐40mm, bio , fossil and waste fuel. Furthermore, here are presented
some VLFB solutions in new and in existing industrial and power plant boilers and some solutions for
conversion of coal by biomass. The base of VLFB combustion system makes Gravity Grate (GG) with
characteristic zig‐zag form and moving and burning fuel provided due to gravity. Thanks to constant
moving fuel in GG, good mutual mixture of fuel was achieved, with the air simultaneously as the
presumption of good combustion. Through the zig‐zag pillar of fuel in GG, intensive blowing by primary air
is applied. On the right side by GG is located oblique plate with the arranged nozzles for secondary air, at
the same time providing burning flown fuel particles from GG and stimulating the final combustion of
unburnt gases produced in GG. GG is modular system, so by combining modular units is possible to
achieve combustion chamber needed capacities, ranging from 1 to 300 MWth, as shown in Fig.2, 3, 4, 6.
Corresponding author: Radislav Vujadinović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
16
Thermal Fatigue of Materials
Dušan Petković, Goran Radenković
Abstract: This paper describes the basic mechanisms that lead to the thermal fatigue phenomenon.
Thermal fatigue is a process of damage origination and growth in machine parts and structural
components due to changes in internal energy caused by multiple cyclic or periodic changes of
temperature. This phenomenon is produced basically by cyclic or periodic temperature changes and
complete or partial restriction of thermal deformation. The restriction may be due to external or internal
factors. The results obtained so far suggest that thermal fatigue has much in common with creep and
mechanical fatigue. At this time it is not possible to present a complete general mechanism for damage
growth in thermal fatigue, so that further research is needed. This complex phenomenon requires further
research efforts. The aim of this paper is to highlight the thermal fatigue phenomenon, its importance and
consequences which these thermal stresses can cause. In this paper the main concepts which appear in
this field was mentioned and pointed out the importance of thermal stresses. Mechanisms of initiation
and propagation of the thermal fatigue cracks are also briefly mentioned.
Keywords: Thermal fatigue, Thermal stress, Crack propagation, Failure mechanism.
Corresponding author: Dušan Petković, e‐mail: [email protected]
3. New and Renewable Energy Sources
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
18
Potential Fire Hazards of Renewable Energy - Horizons of Tomorrow
Miloš Banjac, Barbara Vidaković
Abstract: Dramatic climate change, caused by over consumption of coal, oil and other traditional energy
sources, as well as exhaustion of their reserves, imposed technological need to look for their substitution
with new, renewable energy sources. The exploitation of these new forms of energy, solar, wind, earth
and bio‐fuels, initiated the development and application of new technologies, so far unused in practice.
Rapid development and wide application of installations for use of renewable energy in many households
and companies opened a whole new risk and danger in the fire protection field. With the purpose of
introducing this problem to engineers in the area of fire protection, health and safety at work, this paper
systematically presents various types of facilities for exploitation of renewable energy sources as well as
potential dangers, risks and issues related to their safe operation.
Keywords: fire hazard, renewable energy sources, risk assessment, protection.
Corresponding author: Miloš Banjac, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
19
Possibilities and Directions for Participation of Available RES in Macedonia with
Scenarios for Achieving the 20/20/20 Goal of the EC
Mile Dimitrovski
Abstract: Protection of the environment and in particular to reducing greenhouse gas emissions, energy
import dependency of Macedonia, as well as providing greater diversity and thus security of supply of
energy, impose the necessity of further increasing the share of renewable energy sources. Macedonia has
a certain amount of non‐renewable energy sources, which are limited and also has available large
amounts of renewable energy sources, which are used only to a certain extent and the country has
relatively high utilization of renewable energy sources in total final energy consumption. The 20/20/20
Goal of the EC could be partly achieved by the energy generated from renewable sources consisting of
electricity (generated from hydro, wind and solar plants, biomass and biogas plants) and with the heat
generated from renewable sources (biomass, solar energy and geothermal energy) and biofuels.
Keywords: Biofuels, Climatic – Energy scenario 20/20/20, Energy Balance, Renewable Energy Sources.
Corresponding author: Mile Dimitrovski, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
20
Optical Design of a Solar Parabolic Concentrator Based on Square Flat Facets
Saša R. Pavlović, Velimir P. Stefanović, Ivan Stojanović, Suad Suljković, Dragan Kuštrimović
Abstract: We present a procedure to a design a square facet concentrator for laboratory –scale research
on medium – temperature thermal processes. The facet concentrator approximates a parabolic surface
with a number of flat square facets supported by a parabolic frame and having two edges perpendicular to
the concentrator axis. The optimum size of facets and their position of each facet are found by employing
Monte Carlo ray tracing analysis to achieve desired flux characteristics in the focal plane. A square facet
parabolic solar concentrator with realistic specularly surface and facet positioning accuracy will deliver up
to 19.628 kW of radiative power over a 25cm radius disk located in the focal plane on the focal length of
150 cm with average concentrating ratio exceeding 1200. The parabolic concentrator approximates an
ideal truncated circular paraboloid with square flat facets supported on a parabolic frame and having two
edges perpendicular to the concentrator axis. Analytical geometry and the Monte Carlo ray tracing
method are used to analyze the optical performance of the concentrator and to identify the set of
geometric concentrator parameters that allow for flux characteristics suitable for medium and high ‐
temperature applications.
Keywords: Monte Carlo method, Parabolic concentrator, Focal flux, Ray tracing analysis, TracePro
software.
Corresponding author: Saša R. Pavlović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
21
Techno-economic Analysis of Photovoltaic-based Stand-alone Power System for
Supply of Metrological Masts’ Equipment
Saša Stojković, Vukman Bakić
Abstract: The paper presents the results of techno‐economic analysis of photovoltaic‐based system for
power supply of meteorological masts for wind assessment. Electrical load consists of modern digital
technology measuring equipment (anemometers, wind vanes, temperature and pressure sensors,
hygrometers, and so on), characterized as practically constant load. The obstacle lights are switched on
during night due to air traffic security. Power system consists of a certain number of photovoltaic (PV)
panels, batteries for electric energy storage, as well as charge controllers. Technical constraint is that
power supply of met masts must not be interrupted due to huge importance of measuring data for wind
assessment, which are to be used for wind farm dimensioning. Economic analysis is carried out by “Life
Cycling Costs (LCC)” method, and optimization criterion is the lowest cost of the power system.
Optimization variables were components’ sizes (number of units for PV panels and batteries), and PV
slopes. Furthermore, sensitivity analysis was carried out, and influence of the elements’ prices, interest
rates and panels’ slopes was analyzed. The analysis was done using HOMER software tool. The results of
the analysis show that for stand‐alone PV/battery power system feeding 40 W during day, and 80 W
during night the number of panels and batteries is relatively high, thus making the system considerably
expensive.
Keywords: Stand‐alone system, Photovoltaic (PV) system, HOMER, Solar power system, Meteorological
mast.
Corresponding author: Saša Stojković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
22
Solar Drying of Fruits and Vegetables
Filip Mojsovski
Abstract: For on‐farm drying of small quantities of agricultural products, convective dryer with shelves
was developed. A prototype solar farm dryer for fruits and vegetables was produced. Test runs with the
dryer were carried out over a long period of time, at many locations across the country, in effort to reach
the correct drying conditions.
Keywords: psychrometrics, food drying, solar dryer, thermal storage, tomato, raspberry.
Corresponding author: Filip Mojsovski, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
23
Comparative Analysis Between Two Methods for
Temperature Measurement of PV panels
Uglješa Jovanović, Igor Jovanović, Zoran Petrušić, Dragan Mančić
Abstract: In this paper a comparative analysis between two methods for temperature measurement of
photovoltaic (PV) panels is presented whereas these methods are contact and non‐contact. For contact
method a DS18S20 temperature sensor is selected and for non‐contact it is a MLX90614. Both sensors
were implemented in a single microcontroller based test system. A virtual instrument made in LabVIEW is
created to monitor the operation and data acquisition as well as data storage. The accuracy of sensors is
not in issue hence it has not been evaluated, but their sensitivity to thermal gradient and ability to
measure temperature of PV panels. The main purpose of this study is to properly evaluate the sensors
before implementing them in the system for temperature measurement of PV panels.
Keywords: Contact and non‐contact temperature sensors, microcontroller, temperature measurement,
virtual instrument.
Corresponding author: Uglješa Jovanović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
24
Technical and Economic Analysis of Hybrid Wind-photovoltaic Power System for
Supply of Meteorological Masts’ Measuring Equipment
Saša Stojković, Vukman Bakić
Abstract: The paper presents the results of both technical and economic analysis of the hybrid power
system which supplies measuring equipment and obstacle lights of the meteorological masts for wind
assessment. The system consists of a certain number of photovoltaic (PV) panels, batteries for electrical
energy storage and one small power wind generator. The system is stand‐alone, with no possibility of
connection to distribution network. The second technical constraint is absence of diesel or gasoline
generator, while the third constraint relates to operation continuity. It is demanded that electrical energy
must be available during 100% of time due to huge importance of wind measuring data. The load consists
of meteorological equipment for measuring, acquiring, and sending data remotely by the modem, as well
as obstacle lights for air traffic. It is supposed that load is 40 W during the day and 80 W during night. The
basic goal of the analysis is to determine the advantage of hybrid wind‐photovoltaic power system over
PV system alone, regarding the time complementarity of power resources (wind and sun). Economic
analysis is carried out using “Life Cycling Costs (LCC)“ method, as optimization criterion is minimum
system cost. The analysis was done using HOMER software tool. Results of the analysis show that hybrid
wind/PV/battery power system is much more efficient than the system which would consist of PV panels
and batteries alone, since a lower number of storage batteries are needed.
Keywords: Hybrid power system, Wind‐photovoltaic (PV) system, HOMER, Meteorological mast,
Renewable energy.
Corresponding author: Saša Stojković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
25
Technical Feasibility and Financial Analysis of Hybrid Wind-photovoltaic System for
Supply of One Educational Institution
Saša Stojković, Snežana Dragićević
Abstract: The paper presents the results of analysis of technical feasibility of the grid‐connected hybrid
system for power supply of one educational institution. The system consists of a certain number of
photovoltaic (PV) arrays, as well as small wind generators with total power of 1 kW, 3 kW and 5 kW. The
system is connected to distribution network via appropriate inverter. The basic goal is to determine
reducing the bill for electric energy, as well as pollutant emission reduction in the case of predefined load
diagram. Detailed economic analysis is carried out using “Life Cycling Costs (LCC)” method. The money
saving is determined in the cases of “normal” conditions about wind and solar energy (Belgrade). Typical
meteorological year data (TMY2) were used by HOMER software tool. Results of the analysis show that
hybrid wind/PV power system is economically viable.
Keywords: Energy efficiency, Renewable energy source, Solar energy, Wind energy, System Advisor Model
software, HOMER software.
Corresponding author: Saša Stojković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
26
Current State Wind Energy Utilisation in the Republic of Macedonia
Monika Lutovska, Vladimir Mijakovski, Cvete Dimitrieska, Vangelče Mitrevski
Abstract: Wind energy as renewable energy source with the highest growth rate in the last two decades,
is considered as a very important source of electricity for the future. According to the study WIND FORCE
which is funded and conducted by the EU, the share of wind energy in the global world electricity
generation in 2020 is estimated at 12%. So far, several studies for determination of most suitable locations
for construction of wind farms have been made in Macedonia. According to a study prepared by AWS
Truewind, atlas of wind energy potential of Macedonia is made. 15 most suitable locations for building of
wind farms determined out of this study. According to the wind map and according to conducted
measurements at 4 locations, projected installed capacity by location varies from 20 MW to 30 MW. State
owned electricity producing company (JSC Macedonian Power Plant ‐ ELEM), earlier this year, on a
location near Bogdanci, started with construction of first wind farm in the country.
Keywords: Wind, Energy, Wind farm.
Corresponding author: Monika Lutovska, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
27
Agricultural biomass utilization for energy purposes
Dejan Đurović, Branislav Repić, Dragoljub Dakić, Aleksandar Erić, Stevan Nemoda
Abstract: Biomass is one of key renewable energy sources in the Republic of Serbia. This is the reason for
the development of cheap thermal devices burning biomass from agricultural production as quite
available and cheap energy source. Researches in this area are very complex and in order to obtain
reliable data it is necessary to carry out theoretical and experimental research of the process. Therefore,
efforts have been made in the Laboratory for Thermal Engineering and Energy of the "Vinča" Institute to
develop a technology for utilizing bales of various sizes and shapes for energy production. Satisfactory test
results with low CO emission levels and stable thermal output of the 1.5 MW hot water boiler with
cigarette type of biomass combustion, for the purposes of greenhouse heating –– led to the new project
for building up the first combined heat and power (electricity) production facility (CHP), which will use
agricultural biomass as a fuel, in Serbia. This project will be financed by Swiss government. CHP plant will
be used for heating primary school, hospital and one hectare of greenhouse.
Keywords: Biomass, CHP, cigarette combustion, CO emission, greenhouse.
Corresponding author: Dejan Đurović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
28
Biogas – Overview of the Possibilities for Implementation
in the Macedonian Agricultural Sector
Dame Dimitrovski, Mile Dimitrovski, Gordana Popsimonova, Done Tashevski
Abstract: The subject of the investigation of the article is determining the possible production of biogas in
the rural areas of the Republic of Macedonia and determining specific biogas application having in mind
the state of the art in the field, and the state of development of the agricultural sector. In the past years
Macedonian agriculture had few failed projects for production and utilization of biogas. The paper is
observing the potentials of biogas production, pros and contras for production and utilization of the
biogas. Integrated approach for utilization of biogas in the rural area has specific value in the time of
degradation of agricultural land and nonfunctional energy communities in the country. Few suggested
applications are developed that can influence the bust of the agricultural production, lower the expenses
and contribute to positive environmental impact.
Keywords: Biogas, Energy Conversion, GHG.
Corresponding author: Dame Dimitrovski, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
29
Utilization of crude glycerol for the production of biofuels
Bojana Danilović, Dragiša Savić, Vlada Veljković
Abstract: The production of biodiesel provides few by‐products which can be further processed into
valuable products. Crude glycerol obtained from biodiesel production has great potential as the source of
carbon in different microbial processes. Besides for the production of chemicals it can be used for the
production of biofuels. This paper reviews the possibilities of the use of crude glycerol as sole or co‐
substrate in the production of biofuels. The addition of crude glycerol to the process of anaerobic
digestion can contribute to the increase of both biogas production rate and methane yield. In some
processes the fourfold increase of biogas yield can be achieved by the addition of 4% of glycerol. Also,
crude glycerol can be used in order to overcome the barriers of low production rates and yields during the
production of biohydrogen. Additionally, these processes offer advantage in the terms of municipal solid
waste and manure treatment.
Keywords: crude glycerol, biogas, biohydrogen.
Corresponding author: Dragiša Savić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
30
Renewable energy potential in the Rusanda rehabilitation center
Milana Perić, Milovan Medojević
Abstract: Energy efficiency and the rational use of energy is one of development priorities of the Republic
of Serbia, while the reduction of energy consumption from conventional sources and exploitation of
renewable energy sources is an imperative for achieving this goal. The aim of this paper is to show the
possibilities and potential of applicable measures to increase energy efficiency as well as integration of
renewable energy sources the in current energy system of Rusanda rehabilitation center facility, located in
Melenci near Zrenjanin .This paper analyzes the existing energy systems of center and upon that analysis
the corresponding energy indicators were created. These indicators offer a quick insight into the manner
of overall system functioning. Center has recognized the potential of renewable energy sources utilization
and special attention was paid to solar and geothermal energy.
Keywords: renewable sources, potential, geothermal energy, solar energy, energy efficiency.
Corresponding author: Milana Perić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
31
Guide Vane Position Control of the Mini Hydro Power Plant by
Digital Sliding Mode with Additional Integral Action
Vladislav Blagojević, Miodrag Stojiljković, Živan Spasić
Abstract: The paper deals with the task of achieving the desired position of the hydraulic cylinder's piston
that is connected to the guided vane ring of the mini hydro power plant no matter on disturbances. The
purposes of the guide vanes are to control the water flow through the turbine. By varying the position of
the guide vanes the water flow is altered and the speed of the machine can then be controlled. In order to
represent as best as possible a real physical model, the mathematical model of the servo hydraulic system
with a hydraulic cylinder and proportional valve is designed. The control system is designed by applying
the variable structure system theory. The applied control algorithm is based on the digital sliding mode
with additional integral action. The conducted simulations have demonstrated that this control algorithm
provides a satisfactory positioning and great robustness.
Keywords: Mini hydro power plant, Guide Vane, Hydraulic system, Digital sliding mode, Integral action.
Corresponding author: Vladislav Blagojević, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
32
Recent Progress in Biomass Pyrolysis/Gasification Technologies
Velimir Stefanović, Andrijana Stojanović, Saša Pavlović
Abstract: The conversion of biomass by gasification into a fuel suitable for use in a gas engine increases
greatly the potential usefulness of biomass as a renewable resource. Gasification is a robust proven
technology that can be operated either as a simple, low technology system based on a fixed‐bed gasifier,
or as a more sophisticated system using fluidized‐bed technology. The properties of the biomass feedstock
and its preparation are key design parameters when selecting the gasifier system. Electricity generation
using a gas engine operating on gas produced by the gasification of biomass is applicable equally to both
the developed world (as a means of reducing greenhouse gas emissions by replacing fossil fuel) and to the
developing world (by providing electricity in rural areas derived from traditional biomass). In this review
we will be discussing existing techniques and recent progress in gasification and pyrolysis techniques for
the conversion of cellulosic biomass into a viable source of energy. The focus is given to biomass pyrolysis
for production of bio‐oil, co‐firing of biomass and coal and the use of co‐gasification and co‐pyrolysis, the
combination of pyrolysis and gasification to process pyrolysis products to syngas through gasification and
liquifaction of syngas.
Keywords: biomass gasification, biomass pyrolysis, co‐firing, biofuels, syngas.
Corresponding author: Andrijana Stojanović, e‐mail: [email protected]
4. Mathematical Modeling and Numerical Simulation
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
34
Dimensioning of Underground Vertical Heat Exchangers for Geothermal Heat Pump
Miloš Banjac, Zara Komnenić
Abstract: Ground source heat pump or a geothermal heat pump is a central heating system that transfers
thermal energy from the ground ‐ as a heat source, to the heating object ‐ as a heat sink, against a
temperature gradient. Ground source heat pump employs a heat exchanger in contact with the ground or
groundwater to extract thermal energy from the soil. These underground heat exchangers (GHE) are
consisted of a system of tubes that form the so‐called closed outer loop in which a mixture of water and
antifreeze circulates. Closed loop tubing can be installed horizontally as a loop field in trenches or
vertically as a series of long U‐shapes in wells. The size is the one of the loop tubing, i.e. the dimensioning
of underground heat exchanger is the most demanding and the most sensitive part of the calculation.
Besides heating load of the building being heated, the dimension of underground heat exchanger also
depends on the soil type and moisture content, the ground temperature and the dynamics and duration
of extraction of thermal energy from soil. Three analytical methods for dimensioning vertical underground
heat exchanger are presented in this work. The results obtained through analysis and comparisons have
shown that different calculation methods lead to variations in dimensioning in accordance to the applied
method.
Keywords: geothermal energy, ground source heat pump, dimensioning methods, vertical underground
heat exchanger.
Corresponding author: Miloš Banjac, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
35
Heat exchangers comparation
Kire Popovski, Igor Andeevski
Abstract: Extended surface heat exchangers are used for water and air as operating mediums, and can be
differentiated by the ribs shape. The one has sinuous type ribs, while the other one has flat lamella ribs. In
this paper comparison between both types of heat exchangers is made with reference to air velocity in the
minimum flow cross ‐ section and Reynolds' number. Better heat transfer can be provide using exchanger
with higher values of coefficient r and factor ja. Computer program for mathematical model is made and
graphical representation or the results is given.
Keywords: heat exchanger, heat transfer.
Corresponding author: Kire Popovski, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
36
Modeling Thermal Processes Using Bond Graphs
Gordana Janevska
Abstract: Bond graphs represent a systematic method for the modeling of systems in physics and
engineering. It is an advantage that systems from different domains (electrical, mechanical, hydraulic,
thermodynamic) are described in the same way. Bond graphs are a domain‐independent graphical
description of dynamic behavior of physical systems. The paper introduces an approach of the bond graph
modeling applied to thermal processes. The fundamental theory of bond graph focused on thermal
process is explored by considering the example of bath heated by hot fluid. Furthermore, a method to
systematically build a bond graph starting from an ideal physical model is given. In addition, procedure to
generate mathematical equations and block diagram out of a causal bond graph is presented.
Keywords: Bond Graphs, Modeling dynamic systems, Thermal processes.
Corresponding author: Gordana Janevska, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
37
Referent Wind Speed and Turbulence Intensity Estimation and
on-Site Wind Turbines Classification
Žarko Stevanović, Nikola Mirkov, Žana Stevanović, Borislav Grubor, Maja Đurović-Petrović
Abstract: The correct prediction of the maximum wind speed as well as wind turbulence intensity that are
expected to occur on a large time interval and consecutively the definition of the wind turbine class that is
to be installed in a given wind farm site is of crucial importance to the wind farm development. The
maximum wind speed is defined as extreme wind or reference wind speed by the standard IEC 61400‐1. A
turbine designed for a wind turbine class with a reference wind speed and estimated turbulence intensity,
is designed to withstand climates for which the extreme ten minutes average wind speed with a
recurrence period of future 50 years at turbine hub height is lower than or equal to reference wind speed
for the specific site.
This paper is dealing with uncertainty analyses of different methodologies for estimating the extreme
wind as well as turbulence intensity from available experimental datasets and uses it to guide the wind
turbine class definition. Obtained results from datasets based on two and three years measurement
period respectively have been compared and perform cost‐benefit analysis related to uncertainty of
calculated extreme wind and turbulence intensity, crucial for definition of required period for efficient site
characteristics measurement campaign. Uncertainty assessment as well as methodology of extreme wind
calculation is based on statistical tools from General Extreme Value theory.
Furthermore, from the given climatology data at the mast location, and digital terrain data, it is presented
how wind turbine class can be estimated at different wind turbines locations inside the wind farm using
Computational Fluid Dynamics technique coupled with General Extreme Value theory.
Keywords: Wind Energy, Extreme Wind, Wind Turbulence Intensity.
Corresponding author: Žarko Stevanović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
38
Wind Load Modeling and Structural Response of Guyed Mast
Vukman Bakić, Milada Pezo, Gordana Kastratović, Nenad Vidanović
Abstract: Guyed masts are used for wireless communication, meteorological measurements, and even for
power transmission. The behavior of the mast is non‐linear due to its slenderness and compliant ‘guy‐
support’ system. For a guyed mast, wind load is the main factor affecting the stability of the structure. This
paper presents the results of modeling wind characteristics and associated dynamic response of a 139 m
tall guyed mast in ambient wind conditions. Modeling were performed for four wind velocities, 10 m/s, 20
m/s, 30 m/s and 40 m/s. The commercial finite element software ANSYS was used for finite element
modeling and numerical simulation of a guyed mast exposed to wind action.
Keywords: Modeling, guyed mast, wind loading.
Corresponding author: Milada Pezo, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
39
Numerical Investigation of Thermal Processes in Shell and Tube Heat Exchanger
Mića Vukić, Predrag Živković, Mladen Tomić, Ivan Stojanović
Abstract: Shell and tube heat exchangers (STHE) are one of the most often used apparatuses in chemical
industry. One of STHE manufacturer’s main goals is to improve their exploitation reliability and efficiency.
Two approaches in STHE design improve are possible: experimental investigation, which is very expensive
and long‐lasting, because of shell side complex geometry, and numerical investigations. Numerical
simulations can be used to check the old and to develop new, more efficient STHE designs. In this paper,
the results of the numerical simulations of fluid flow and heat transfer in laboratory experimental STHE
are presented. Numerical simulation has been performed by using PHOENICS code. The tube bundle has
been modeled by using the concept of porous media. Standard k‐� turbulence model has been used.
Keywords: Heat exchanger, Local heat transfer, Numerical.
Corresponding author: Mića Vukić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
40
CFD Analysis of Forced Convection Heat Transfer
Cu-Water Nanofluids in Circular Tube
Kamil Arslan
Abstract: A nanofluid is defined as a stable, uniform suspension of nanometer sized solid particles (<100
nm) in conventional liquids such as water. Solid particles have greater thermal conductivity than fluids.
Therefore, using nanofluids in engineering devices mostly enhance heat transfer. Nanofluids are expected
to be used mostly in numerous applications in industry such as heat exchanger and cooling devices in the
future. In this study, forced convection heat transfer flow of Cu‐water nanofluid for different volume
fractions in a circular tube is numerically investigated. Water with Cu nanoparticles with a spherical size of
100 nm diameter is used as the heat transfer medium. Circular tube is heated at uniform heat flux. The
study is performed under laminar and turbulent flow condition. The three‐dimensional flow with
negligible buoyancy effects and viscous dissipation is regarded as steady‐state. The results of numerical
study are validated with experimental data in literature. Flow fields and temperature profiles in the
circular tube are investigated detail. New engineering correlations are obtained for three‐dimensional
numerical studies.
Keywords: CFD, Circular Tube, Cu‐Water Nanofluid, Forced Convection, Heat Transfer Enhancement.
Corresponding author: Kamil Arslan, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
41
Flow Simulation and Noise Prediction in Axial Fans
Altin Dorri
Abstract: Flow field around an axial fan surrounded by a round canal and noise propagation from it were
numerically studied. The numerical simulation was carried out by a Large eddy simulation (LES) and the
noise propagation is predicted by a hybrid method where LES provided acoustic sources to a acoustic
analogy. Results of the LES showed that maximum surface pressures occurred at blade tips which can be
considered as the main source of the noise generation.
Keywords: Axial fans, Noise prediction, Simulations.
Corresponding author: Altin Dorri, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
42
Numerical Investigation of the Influence of Tip Clearance on
Reversible Axial Fan Characteristics
Živan Spasić, Božidar Bogdanović, Vladislav Blagojević, Jasmina Bogdanović-Jovanović
Abstract: Aerodynamic characteristics of reversible axial fans are mainly defined by the choice of basic
design parameters of the impeller and its blades. Aerodynamic characteristics of reversible axial fans are
significantly affected by tip clearance which is the minimum distance between the tip of the fan blades
and the shroud. The size of tip clearance affects the flow structure which is also reflected on the operating
characteristics. This paper numerically investigates the influence of tip clearance on the characteristics of
a low pressure reversible axial fan with the casing diameter D′e=635 mm, and flow parameters: volumetric
flow Q = 3.61 m3/s, total pressure rise Δptot=180 Pa and rotation speed n=1405 min‐1. Numerical
simulations were performed only for the reversible axial fan with an impeller, with blades that have
straight profiles, for three values of tip clearance: 1mm, 2mm, and 3 mm. Software package ANSYS CFX
was used for the numerical simulation of flow. The results of numerical simulations are presented in
graphs p(Q), (Q and P(Q, for different sizes of tip clearance. On the basis of simulation and analysis of
the obtained characteristics, it is concluded that the increase in radial clearance of 1 mm causes a drop in
total pressure increment in the fan for about 3%, a drop in the fan efficiency of about 0.8 % and power
reduction of about 2% for the whole range of simulated flow.
Keywords: Axial Fan, Tip Clearance, Characteristics, Numerical Simulations.
Corresponding author: Živan Spasić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
43
Review of Critical Heat Flux Predictions
Andrijana Stojanović, Vladimir Stevanović, Dragoljub Živković, Milada Pezo, Ivan Tomanović
Abstract: Understanding the CHF phenomenon, and in particular, the accurate prediction of flow
conditions that can lead to CHF, are important for the safe and efficient operation of many heat transfer
units including nuclear fission power reactors, fossil fuel boilers, fusion reactors, electronic chips, etc. CHF
is expected to occur during transients than steady‐state conditions. Therefore, knowledge of transient
CHF is of great importance for the safety evaluation of heat transfer units under transient conditions. The
crucial and practical importance of the CHF and the extreme physical complexity of the critical
phenomenon justify the tremendous number of experimental CHF studies that have been carried out
during the last 50 years. More research came to pay attention to the numerical simulation of boiling and
tried to find more information, which may be difficult to be found by experiments. In this paper, the
existing CHF modeling studies are discussed in order to understand the phenomena leading to CHF.
Keywords: critical heat flux, burnout, boiling crisis.
Corresponding author: Andrijana Stojanović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
44
Determination of centrifugal pump operating parameters in turbine operating regime
Živojin Stamenković, Jasmina Bogdanović-Jovanović, Jelena Manojlović
Abstract: In recent times pump‐as‐turbine (PAT) systems have become very popular. In such a system a
pump is operated in reverse so that it functions as a turbine. This is especially popular in areas where the
availability of turbines is limited as pumps are typically easier to get hold. An investigation showing the
possibility of incorporation PAT aggregate in water supply system of city of Nis has been done recently.
Since this topic has become very interesting in the world, in this paper presents a review of BUTU method
and also the usage of CFX software in order to determine operating parameters of a pump operating in
turbine regime. It is presented an example of centrifugal pump operating in turbine regime and
comparison of results obtained using BUTU method and numerical simulations of fluid flow.
Keywords: PAT system, BUTU method, numerical simulation.
Corresponding author: Živojin Stamenković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
45
Euler-Euler Granular Flow Model Applied on
Numerical Simulation of Liquid Fuels Combustion in a Fluidized Bed
Stevan Đ. Nemoda, Milica R. Mladenović, Dragoljub V. Dakić, Mirko S. Komatina,
Aleksandar M. Erić, Milijana J. Paprika
Abstract: In the present study a two‐fluid Eulerian‐Eulerian formulation incorporating the kinetic theory of
granular flow (KTGF) was applied to gas and solid phase flow prediction in the fluidized bed reactor.
Despite rigorous mathematical modeling of the associated physics, the drag laws used in the model
continue to be semi‐empirical in nature. Primarily, the semi‐empirical procedure is proposed for
prediction the drag law coefficients that correspond to real minimum fluidization conditions. In adopted
CFD two phase model of bubbled fluidization the energy and chemical reactions (species transport)
equations have been included. A series of numerical experiments was performed with combustion of the
liquid fuels without, and with significant water content. These estimates are unsteady, and they modeled
the time period which corresponds to flow passing time throw reactor column. Obtained results are of
interest for start of fluidization reactors when CO emission is critical. Also, the calculations were compared
with the experiments on a fluidized bed pilot furnace with in‐bed feeding of liquid waste fuels.
Keywords: CFD model, combustion, fluidized bed, granular flow, liquid fuels.
Corresponding author: Stevan Đ. Nemoda, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
46
A Parametric Study on Correlations for Transport Parameters in
Fixed Bed Regenerators
Milan Đorđević, Šefik Bajmak, Marko Mančić
Abstract: Several types of mathematical models approximating complex physical processes taking place in
packed bed heat regenerators are considered. Complexity of these phenomena makes an exact
mathematical description virtually impossible and simplified mathematical models in terms of averaged
quantities have been developed for their description. A number of theoretical and experimental
correlations are presented for evaluation of the effective thermal properties of packed beds. Presented
comparisons between the predictions from these correlations over a range of physical parameters and
working conditions assumed that the bed geometry is cylindrical with spherical particles of random
arrangement, the fluid and the solid thermophysical properties are temperature independents, there is no
chemical reactions and heat generation within the bed and there are some heat losses to the ambient.
Results indicate that there is no universal packed bed regenerator model and each problem should be
carefully analyzed to identify allowed simplifying assumptions and correlations for transport parameters.
Keywords: Correlations for Transport Parameters, Mathematical Modeling, Packed Bed Heat
Regenerators.
Corresponding author: Milan Đorđević, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
47
Numerical Prediction of Drag Coefficient for Lattice Structures
Milada Pezo, Vukman Bakić, Gordana Kastratović, Nenad Vidanović
Abstract: Wind load is the main factor affecting the stability of the structure for guyed masts.
Determination of drag coefficient forlattice structure has not been sufficiently investigate in past. There
are numerous results concerning simplified structures such as sphere or cylinder, but lattice structures
have been neglected in previous research. Numerical simulations of a flow around one segment of the
mast are presented in this paper. Three‐dimensional numerical simulations of the segment of a mast
exposed to a wind action with three models of turbulence are performed. Modeling were performed for
four wind velocities, 10 m/s, 20 m/s, 30 m/s and 40 m/s. Reynolds number for those velocities
corresponds to turbulence flow. Three models of turbulence: standard k‐ε model, RNG k‐ε model and
Reynolds stress model were used and compared with available experimental results. Drag coefficient was
calculated based on the knowledgeof pressure field, flow fieldanda reference area. The angle of attack
was also taken into account for determine the drag coefficient.
Keywords: Drag coefficient, lattice structure, CFD.
Corresponding author: Milada Pezo, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
48
Comparison between the energy integration of processes
for 1G/2G ethanol production and bioelectricity
Cássia M. Oliveira, Antonio J. G. Cruz, Caliane B. B. Costa
Abstract: The increase in demand for biofuels has driven the development of new technologies such as
ethanol production from sugarcane bagasse hydrolysis. This work performed energy integration in
processes for 1G/2G ethanol and electric power production using Pinch analysis. Four different scenarios
were considered in these biorefineries, since two different types of pretreatment for bagasse
(hydrothermal and diluted acid ones) and inclusion or not of pentose fermentation step were considered.
The processes with hydrothermal and diluted acid pretreatments which include pentose fermentation
step have higher ethanol production when compared to processes that do not make use of pentose
fraction to produce ethanol, but steam consumption increases in the same order of magnitude of ethanol
production. For the four scenarios evaluated the application of energy integration demonstrated a
reduction in energy consumption of more than 50% compared to the corresponding cases without
integration and of more than 30% compared to partially integrated processes, as commonly found in
Brazilian industrial plants. Besides the economical advantage, due to the decrease in costs of hot and cold
utilities, energy integrated processes increase bagasse availability for production of second generation
ethanol.
Keywords: Biorefinery, Energy Integration, Ethanol, Pinch, Pretreatment.
Corresponding author: Caliane B. B. Costa, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
49
Mathematical models for evaluating evaporation rates from
free water surface of indoor swimming pools
Marko Mančić, Dragoljub Živković, Jelena Manojlović, Milena Todorović
Abstract: Indoor swimming pool buildings are significant energy consumers. Energy consumption of a
typical indoor swimming pool consists of: indoor swimming pool hall ventilation 45%, swimming pool
water heating 33%, heating and air‐conditioning for the rest of the building 10%, electric equipment and
lighting 9% and sanitary hot water 3%. The greatest energy consumer is the swimming pool hall where
free water surface evaporation takes place, increasing air humidity in the hall and causing a demand of
fresh water supply for the pool. This increases energy consumption for heating and ventilation of the hall,
and for maintaining pool water temperature with the fresh water supply. Mathematical modeling of water
evaporation from free water surface of the swimming pool has brought much attention in research over
the years. In this paper, an energy model of a swimming pool hall was made, with a special focus on
mathematical models for prediction of free water surface evaporation rates in swimming pools. A review
of mathematical models of water surface evaporation has been made, with special consideration to
determination of the evaporation coefficient. A general mathematical model of water evaporation from
the swimming pool water surface is presented in the paper. Mathematical model of the swimming pool
hall is designed to be used for simulation of the indoor swimming pool multi‐zone building model.
Keywords: evaporation rate, indoor swimming pool, mathematical model.
Corresponding author: Marko Mančić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
50
Software for Testing the Heat Transfer and Pressure Drop
in Vertical Thermosiphon Reboiler
Sonja Stefanov, Dragan Skobalj
Abstract: Vertical thermo‐siphon re‐boilers are ofen used in the chemical industry, especially in
petrochemical facilities. Many authors have dealt with the estimations of the pressure drop and heat
transfer in these devices. This work will present a program and estimation of the vertical thermo‐siphon
re‐boiler, using the FORTRAN77 programming language that is based on the method of Sarm and al.
Unlike previously proposed approaches and the literature this method in the estimation of the pressure
drop in pipes apparatus, takes into account the mechanism of the two‐phase flow. The results of the
program are analyzed in detail and discussed in the exploitation of real examples.
Keywords: Software, Hear Transfer, Pressure Drop, Vertical Thermosiphon Reboiler.
Corresponding author: Sonja Stefanov, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
51
Numerical Simulation of Friction Stir Welding
Miroslav Mijajlović, Dragan Milčić, Miodrag Milčić
Abstract: Friction stir welding is a solid‐state welding technique that utilizes thermo‐mechanical influence
of the rotating welding tool on parent material resulting with monolith joint ‐ weld. On the contact of
welding tool and parent material, significant stirring and deformation of parent material appears, and
during this process mechanical energy is partially transformed into heat. Generated heat affects the
temperature of the welding tool and parent material so proposed analytical model for estimation of the
amount of generated heat can be verified by temperature: analytically determined heat is used for
numerical estimation of the parent material's temperature and this temperature is compared to the
experimentally determined temperature. Numerical solution for analytical estimation of welding plates
temperature is estimated using finite difference method ‐ explicit scheme with adaptive grid, considering
influence of temperature on material's conductivity, contact conditions between welding tool and parent
material, material flow around welding tool etc.
Keywords: Numerical Simulation, Friction Stir Welding.
Corresponding author: Miroslav Mijajlović, e‐mail: [email protected]
5. Experimental Investigation of Processes
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
54
Experimental Plant for Testing of Agricultural Biomass Combustion
Zoran Čepić, Biljana Miljković, Branka Nakomčić-Smaragdakis, Nevena Šenk, Dušan Marković
Abstract: Agricultural biomass has great potential, but in our country it is used in a very small percentage
for energy purposes. Considering the intense market fluctuations of fossil fuels, and the obligations that
our country has in accordance with the Kyoto Protocol, the use of agricultural biomass as a renewable
energy source becomes significant. There are a number of ways of using biomass for energy purposes, but
combustion is certainly the most dominant one. Devices for combustion of agricultural biomass are still in
the development stage, and today the world market doesn't have a satisfactory solution. In order to
optimize the combustion process, an experimental plant for agricultural biomass combustion was
designed and built. In this experimental plant, it is possible to vary the biomass density and quantity and
the temperature of air used for combustion, because the measured parameters during combustion are
mass and temperature change in combustion chamber. The paper presents the relevant results of
combustion of wheat straw.
Keywords: Agricultural biomass, combustion, experimental plant, wheat straw.
Corresponding author: Zoran Čepić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
55
Investigation of Wood Chips Combustion in Experimental Combustion Chamber
Branislav Stojanović, Jelena Janevski
Abstract: Wood chips are produced from foresting residues and by mechanical treatment it is prepared as
fuel for fully automated boilers. Their main advantage over other fuel types is that they have the shape
and dimensions that are very suitable for transport, storage and dispensing. Also if an automation of the
plant is requested, pellets provide the opportunity to manage such plant operation. By analyzing a
number of pellet combustion boilers solutions, it has been shown that there are some specific
constructional solutions that are different from traditional boilers for combustion of solid fuels. Therefore,
for the experimental combustion chamber the fuel supply from below is adopted. This type of combustion
is characterized by a steady supply of fuel and air for combustion. This paper presents the investigation of
pellets combustion in an experimental combustion chamber. The focus of this research was on the
elimination of CO in the combustion products by lowering the temperature in the boiler combustion
chamber. This was achieved through the varying refractory surface of combustion chambers. The results
show that by increasing the refractory surface of combstion chamber, higher quality of fuel combustion is
achieved, which also allows for a uniform composition of the combustion products during the
discontinuous operation of the boiler. By increasing the combustion chamber wall lining, lower values of
carbon monoxide in combustion products were also obtained.
Keywords: wood chips, combustion, refractory surface.
Corresponding author: Branislav Stojanović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
56
Experimental and Numerical Study of Biomass Combustion in 50 kW Cigar Furnace
Aleksandar M. Erić, Stevan Đ. Nemoda, Dragoljub V. Dakić, Mirko S. Komatina, Branislav S. Repić
Abstract: This paper presents experimental and numerical investigations of baled agricultural biomass
combustion in the furnace capacity of about 50 kW with cigarette combustion method. In experimental
tests measured the characteristic values needed to determine the material and energetic balance, and the
quality of combustion process. As a result of numerical work, 3D CFD model of the combustion process in
the combustion chamber of this type of combustion was developed. The model includes complex thermo
mechanical processes that occur during combustion within a porous layer of bales of biomass and in the
fluid space around it. Combustion processes are considered as stationary, and was taken into account and
the impact of the environment on the temperature field within the model domain. Comparison of the
results showed satisfactory agreement with numerical results, so that the developed mathematical model
could be used to analyze the effects of structural and parametric changes to the facility.
Keywords: Biomass, Combustion, Experimental, Numerical.
Corresponding author: Aleksandar M. Erić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
57
Experimental and numerical research of thermal processes in the TST tanks with
thermal oil and a phase change medium
Goran Živković, Nedžad Rudonja, Mirko Komatina, Branislav Repić
Abstract: This paper surveys a part of the activities (performed during the realization of the third year of
project III 42011 financed by the Ministry of education and science of the Republic of Serbia) on the
development of TST whose storage medium melts at the atmospheric pressure, enabling on that way the
use of the energy of phase change for energy storage. The original experimental setup adapted for use of
paraffin as a phase change media (volume 77 dm3, heating power 2.4 kW) was modified by inserting four
vertically positioned tubes (inner diameter 120 mm) filled by paraffin into the tank. The rest of the tank
was filled with thermal oil. Storage media was cooled by the air which circulates around the tank. The
research was realized in two phases: a) with thermal oil as the only storage media; b) with the
combination of paraffin and thermal oil. Inside the main body of the tank the temperature measurements
were performed by 12 thermocouples, 4 along the tanks height and 3 along the tank radius, and inside the
cylinder filled with paraffin with 4 vertically positioned thermocouples. For the development of the
numerical model of heat transfer and fluid flow processes in TST a commercial numerical package Fluent
12.1 was used, since it possesses its own routine for computation a temperature and flow fields in TST
with the change of phases, but also it allows to user to implement the package with its own model by
using the user define functions. Measurements and the numerical computation were performed for non‐
stationary as well as for stationary working regimes. A good agreement between the numerical and
experimental results was achieved.
Keywords: TES, Measurements, Numerical model, Phase change, Thermal oil, Paraffin.
Corresponding author: Goran Živković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
58
Determining the Theoretical Reliability Functions of the
Thermal Power Systems in Power Plant "Nikola Tesla A"
Dragan Kalaba, Milan Đorđević, Dušan Adamović
Abstract: The objective of this paper is representation of the probabilistic reliability assessment of thermal
power systems. Exploitation research of the reliability of six power units in the fossil fuel power plant
"Nikola Tesla A" during useful life period is based on extensive longtime failure database. By applying the
reliability theory, based on statistics and theory of possibility, and using complex two‐parameter Weibull
distribution, the theoretical reliability functions of specified systems have been determined. Obtained
probabilistic laws of failure occurrences, according to which the random variable behaves, establish a
comprehensive insight in the field of probabilistic power system reliability assessment technique.
Comparison of reliability functions and indices of power units of the same type make possible to acquire a
better knowledge of current system state as well as a more accurate estimation of its behavior during
future exploitation.
Keywords: Fossil Fuel Power Plant System, Reliability, Weibull Distribution.
Corresponding author: Milan Đorđević, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
59
An Experimental Research of Effects of Adding a Supplementary Component
Generated by a Catalytic Reactor on the Combustion of the Primary Fuel at
Internal Combustion Engines
Miloš Milošević, Jovica Pešić, Boban Nikolić, Miodrag Milenković
Abstract: Considering strict restrictions on vehicle exhaust emissions as a part of global environmental
protection policy, as well as the compulsion for having fuel‐efficient vehicles caused by the upcoming
energy crisis reflected through the lack of fossil fuels, in this paper, the effects of adding a supplementary
component on the combustion of the primary fuel at internal combustion engines were experimentally
researched. The experimental results of the research carried out under laboratory conditions on a petrol
engine have shown that the use of a catalytic reactor, an efficient generator of the supplementary
component in the form of a plasma gas working as the endothermic plasma water vapor converter,
improves the energy value of the combustion process which may reflect in the reduction in the primary
fuels consumption, the reduction of the emission of harmful and toxic substances in the exhaust gases,
and increasing engine performances. The proposed system is easy for the installation, it does not require
modification of the equipped engine, it does not extra load vehicle electronic systems, and it is completely
self‐regulating because the amount of the produced gas is directly proportional to the engine load. The
system can be installed on any type of internal combustion engines (diesel/petrol), all engine generations,
and it can be combined to be suitable for different engine capacities.
Keywords: Catalytic Reactor, water vapor, Bubbling Internal Combustion Engines.
Corresponding author: Miloš Milošević, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
60
Experimental investigation of flow-thermal and operating properties
of adsorption filter prototype under climate
Miomir Raos, Ljiljana Živković, Nenad Živković, Jasmina Radosavljević, Milena Jovanović
Abstract: The paper presents the results of experimental research conducted on the original apparatuses
in the laboratory for air quality management at the Faculty of Occupational Safety in Niš. The aim of the
paper is an examination of flow‐thermal parameters, velocities of gas mixture, flow, pressure drop,
temperature, humidity, chemical pollutants test, and performance of the adsorption filter prototype in
the filter‐ventilation system. Examination of flow‐thermal parameters of the observed filter‐ventilation
system was carried out on an experimental setup with a flow rate of gas mixture up to 2000m3/h.
Experimental data were registered with appropriate measuring equipment, which helped us obtain a
picture of the behavior of the adsorption filter prototype compared to simulated parameters of the gas
mixture. By measuring and data acquisition, we reached the assumptions for identifying the observed
process, and thus the possibility of modeling and controlling process parameters.
Keywords: experiment, ventilation, flow‐thermal parameters, air purification, data acquisition, adsorption
filter.
Corresponding author: Miomir Raos
6. Energy Efficiency in Industry, Civil Engineering,
Communal Systems and Traffic
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
62
Survey of Potential Energy Savings in the Building Sector in Serbia
and Needed Investments
Maja N. Todorović, Dragoslav M. Šumarac, Radoslav D. Galić
Abstract: Energy consumption in buildings in Serbia has been growing steadily over the past few years and
account for the largest share of the country’s Total Final Energy Consumption (TFEC). Energy consumption
in buildings is 38% while in industry and traffic is 34% and 28% respectively. In this context, the buildings
sector provides significant opportunities for energy savings. This paper has resulted from the research
done for the “National building energy efficiency Study for Serbia” financed by World Bank and for the
national research projects No. TR 33047 and III 42012, financed by Ministry of Education, Science and
technological Development of Republic of Serbia. The paper presents the results of current energy
consumption in building sector, together with analysis of potential energy savings and assessment of
needed investmens. Also, given is market assessment of the building sector in Serbia, covering public,
residential and commercial buildings, that includes a review of existing market situation, data collection,
identification of gaps and steps to overcome it, justification of assumptions and estimates by walk through
energy audits (WTA), utility data, and information from line ministries. Recommended are cost‐optimal
sets of energy retrofit measures (ERMs) for each subsector, calculated are energy savings and payback
period, and given is an investment assessment for the future period of eight years.
Keywords: building sector, annual energy consumption, energy retrofit measures, potential energy
savings, payback period, needed investments.
Corresponding author: Maja N. Todorović
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
63
Heat pump application for hot water production in a hotel
Sofia-Natalia Boemi, Elli Kyriaki, Thomas Aslanidis, Agis M. Papadopoulos
Abstract: Heat pump systems offer economic alternatives of recovering heat from different sources for
use in various industrial, commercial and residential applications. As the cost of energy continues to rise, it
becomes imperative to save energy and to improve overall energy efficiency. Ii is within this light, that
heat pumps have become a key component in for the heating and cooling and DHW production in
commercial buildings.
The present paper is divided in two main sections. Initially, a review of the methods used in the design and
installation of high efficiency heat pumps is presented, focusing on the combination of heat pumps and
heat distribution systems, with respect to the building envelope’s features and the operational
requirements of the building.
A case study is then discussed, for a five hotel located in Halkidiki, an area in Central Macedonia, Greece.
The hotel replaced the liquefied petroleum gas (lpg) and oil burner that were used for providing hot water
to the spa, the restaurant, the kitchen and half of the rooms (100 rooms of 214 rooms) for the production
of hot water with four heat pumps of 16 kW each. The energy conservation achieved will be discussed, as
well as the feasibility of the intervention.
Keywords: Heat pumps, hot water production, hotel.
Corresponding author: Sofia‐Natalia Boemi, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
64
Possibilities of applying heta lower temperatures level for heating
by using two-stage heat pump
Šefik M. Bajmak, Milan Đorđević
Abstract: The two‐degrees pump is sometimes used into the heating supplying system, when heating
capacity is chosen depending from charge of the heating system. Based of the analysis, of maximum
heating charge the first degree condenser is about 62% from the maximum valve of the heating charge.
Maximum heating charge of the second degree condenser is as equal as maximum value of the heating
charge, hes been established about 78% of total installed power of the first and second degree
compressors’. Also annually energy consumption for the second degree compressor work is about 85‐95%
of the total consumed energy for a season heating. On the conditions’ for the town of Prizren, it is defined
number of hours for used the second degree compressors’ power.
Keywords: heat pumps, heating systems, two‐step.
Corresponding author: Šefik M. Bajmak, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
65
Analysis of the possibilities of using geothermal heat pumps in
the heating and cooling systems with special emphasis spa Ilidža in Peć
Šefik M.Bajmak
Abstract: One of the basic preconditions for a longer stay human in a space is tolerable difference
between the temperature of his body and the environment, that is, it is the difference that natural
temperature controllers human body can compensate. Developing awareness of lower operating costs for
heating and cooling, environmental factors and attempt to take from nature as a greater amount of
heating, respectively, cooling, influenced the emergence of advanced technical solutions. One of the most
interesting are heat pumps that take heat from the ground, on the way to producing 100% of heating or
for heating domestic hot water, use only 25 30% additional energy (usually to the compressor heat pump)
until 70 ‐75% of the energy is taken from the environment (usually ground). Globally, underground
geothermal reservoirs represent a huge potential directly usable energy. The paper analyzes the particular
characteristic of dry rocks and layers of natural groundwater. Featured is the heat content of the soil at a
depth depending on soil properties and temperature dependence of the water layer at depth h . The
procedure for defining the soil temperature, depending on the depth and season (summer, winter).
Keywords: geothermal energy, heat pumps, central heating, central cooling.
Corresponding author: Šefik M. Bajmak, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
66
Usage of Low-temperature Energy from the Cooling Tower
by applying Cascade Heat Pumps
Vladimir I. Mijakovski, Vangelče B. Mitrevski
Abstract: Economic and ecologic justification for the usage of low‐temperature cooling water from the
condensers (cooling towers) of TPP Bitola for heating of greenhouse complex by application of heat
pumps, connected in cascade, is analyzed and presented in this article. The unit is composed out of three
sub‐systems, each having two one‐stage heat pumps working in cascade mode. Calculation of the first
heat pump cascade is made for cooling fluid R407c, while for the second heat pump, cooling fluid R600a
(isobutene) is used. Full techno‐economic analysis of investment and operational costs on the usage of
low‐temperature cooling water at a temperature of 33C, is made. Period of investment payback is also
determined.
Keywords: cascade, heat pump, low temperature
Corresponding author: Vladimir I. Mijakovski, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
67
Refurbishment of Residential Buildings According to Regulation and Policy
Vladimir Jovanovic, Karin Stieldorf
Abstract: According to the First National Energy Efficiency Action Plan of the Republic of Serbia residential
buildings built in 1970s and 1980s are identified as the biggest problem regarding energy consumption in
the country due to the poor thermal properties of their building envelopes. The aim of this paper is to
evaluate building envelope retrofits for a single family house regarding state‐of‐the‐art policy in Serbia.
The paper describes specific measures that can be applied to satisfy current Regulation on Energy
Efficiency in Buildings, First NEEAP and possible incoming energy policy. A case study research and a
simulation in relation to experimental research are combined methodologies. The representative model of
the detached house is positioned in Nis, Serbia. Three retrofit solutions are evaluated through Euro‐
WAEBED and GEBA dynamic simulations. The refurbishments are compared by a reduction of heating
demands, annual savings that vary from 31% to 51% and possibility of overheating in summer. The
findings could be used as a first step in designing a renovation for typical detached houses in Serbia. More
information on benefits of refurbished homes could contribute to the increase of retrofit rates in Serbia.
Keywords: Building envelope, Energy efficiency, Policy, Refurbishment, Regulation, Serbia.
Corresponding author: Vladimir Jovanovic, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
68
Impact of Insulation on School Building Energy Consumption
Snezana Dragićević, Sasa Stojkovic
Abstract: The purpose of this study is to quantify the impact of insulation of various parts of building
envelopes on building energy consumption. Using DesignBuilder, a series of parametric simulation was
conducted to acquire building energy consumption data for a range of U‐values of walls, roof, and
windows of a primary school "Vuk Karadzic" in Čačak, Serbia. Analysis is conducted for annual heat losses
and benefits of the insulation measures of walls, roof and windows respectively. In addition, analysis of
heat gain and loss components was conducted for the purpose of identifying strategies for effectively
installing insulation on different parts of the building envelope. Obtained results show a possibility
measure to improve the energy efficiency of the analyzed school building by decreasing of heating power
up to 34 %.
Keywords: Heat losses, Heating power, Insulation, School.
Corresponding author: Snezana Dragićević, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
69
Determining important factors for improving the energy efficiency,
optimal economic and ecological characteristics of a building
Biserka Marković, Vlada Nikolić, Milica Stojanović, Olivera Nikolić, Vuk Milošević, Stevan Marković
Abstract: This paper shows the analysis of aspects of selected influence parameters for the choice and
optimization of supporting elements and the envelope of the building. On the selected model of the
building the optimal carrying structure is done through the use of prefabricated building technology, and
thus saves the building material, work power, and time for production and erection up to 50%. The
process of architectural design is in this case better, since it offers more freedom in achieving higher
flexibility and adaptability of the building. For valorization of the energy efficiency annual consumption of
the energy for heating is used. The influence of infiltration losses, and the solar and internal gains are
taken into account. The energy saving by replacing the façade, and the loggias are 13%, or 64719 kWh. By
enclosing the loggias the energy saving is 22%, or 58351 kWh.
Keywords: optimization, building technology, supporting structure, building envelope, energy efficiency,
cost‐effectiveness.
Corresponding author: Biserka Marković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
70
Building Facade with Temperature Barrier
in Context of Increasing Building Energy Efficiency
Branislav Stojanović, Jelena Janevski, Milica Stojanović, Marko Ignjatović
Abstract: One of the possible ways to provide heating to the building is using temperature barriers within
the building facades. This type of heating, besides providing significant increase in building energy
efficiency, allows using low‐temperature heating sources. In this paper, special attention is given to
opaque part of the building facade with integrated temperature barrier. Due to fact that this type of
system strongly depends on temperature of this thermal element (barrier) and type and thickness of other
materials of the facade, influence of this parameters on energy efficiency was analyzed in this paper. Since
the simplest and most promising way of using geothermal energy is to use it directly, for our analysis this
source of energy was selected. Building energy needs for heating were obtained for typical residential
multi‐family building in Serbia by using EnergyPlus software. The building with all necessary input for
simulation was modeled in Google SketchUp with aid of Open Studio Plug‐in. Obtained results show that
temperature barrier represent good way to increase building energy efficiency and that applying certain
temperatures within the barrier passive house standard can be achieved.
Keywords: temperature barrier, facade, energy efficiency.
Corresponding author: Branislav Stojanović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
71
Energy efficiency of thermal power plant depending on the
hydraulic load of cooling tower
Mirjana Laković, Milica Jović, Slobodan Mitrović
Abstract: This paper describes the effects of changes in hydraulic load and parameters of the atmospheric
air in the power plant cooling system with wet cooling towers. Decreasing of the hydraulic load in the
cooling tower leads to increasing of the energy efficiency of the plant, due to lower temperature of the
condenser cooling water.
With the change of the parameters of the atmospheric air there is change in the operating conditions of
the cooling tower and thus, temperature of cooled water. Cooling water temperature change affects the
change of the operating conditions of the condenser. Condensing pressure, specific heat consumption and
energy efficiency of the power plant strongly depend on the cooling water temperature. Those
dependences for the actual power plant operating conditions are presented in the paper, in case of the
different hydraulic loads of the cooling towers.
Keywords: cooling tower, hydraulic load, plant energy efficiency.
Corresponding author: Milica Jović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
72
Endogenous and Exogenous Exergy Destruction and Exergoeconomic Evaluation
of Thermal Processes in a Complex Industrial Plant
Goran Vučković, Mirko M. Stojiljković, Gradimir Ilić, Mića Vukić, Miloš Simonović
Abstract: One of the roles of the Exergoeconomy is to provide energy systems designers and operators
with the information, necessary for the improvement of energy systems. It employs both economic
principles and the exergy concept, particularly taking into account the values of individual components’
exergy destruction: the thermodynamic loss due to irreversibilities within a system’s component.
The total exergy destruction occurring in a component is not only due to the component (endogenous
exergy destruction) but is also caused by the inefficiencies of the remaining system components
(exogenous exergy destruction). Hence, the care must be taken when using the total exergy destruction of
a component decisions making to optimize the overall energy system.
In this paper, a complex industrial plant is analyzed using the exergy destruction splitting in a component
into its endogenous part or that part which is due totally to the irreversibilities of the component and its
exogenous part which is due to the irreversibilities of other components within the system. The results
will then be applied to the exergoeconomic analysis with the aim of providing relevant additional
information for energy system optimization.
It is observed that the dominant effect is the of the steam generator. From the total exergy destruction in
the steam generator, 1,097.63 kW or 96.95 % come from internal irreversibility in the component, while
the influence of other components on the loss of useful work in the steam generator is only 3.05 %. Data
from exergoeconomics evaluation indicate that the best effects of increasing the efficiency of the overall
system, can be achieved with interventions on the steam generator, given that the sum of
exergoeconomics and non‐exergoeconomics costs of this component is 46.37 €/h or 80.36 %.
Keywords: exergy, exergy destruction, endogenous, exogenous, exergoeconomics, industry.
Corresponding author: Goran Vučković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
73
Introducing curricula of energy efficiency and renewable energy sources
by TEMPUS project ENERESE
Ćemal Dolićanin, Bojan Kovačić, Edin Dolićanin
Abstract: Bearing in mind the significance of energy efficiency, renewable energy sources and their
environmental impacts, the State University of Novi Pazar (SUNP) has, as a pioneer in Republic of Serbia,
accredited and realised one‐year master study programme Energy Efficiency in Buildings, with the support
of WUS‐Austria, and now, as a coordinator at TEMPUS regional project, in cooperation of six Western
Balkan and four EU universities, it is preparing accreditation and realisation of two‐year master study
programme Energy Efficiency, Renewable Energy Sources and Environmental Impacts (ENERESE). The
ENERESE project intends to educate, train and deliver such specialists within a interdisciplinary and
independent problem‐solving framework. This project will fulfil this need by developing curricula and the
training programmes for integral sustainable energy design. Project aims is to train qualified master
engineers in relatively new and broad interdisciplinary field of energy efficiency and renewable energy
sources in Western Balkan project partner countries.
Keywords: education, energy efficiency, project ENERESE.
Corresponding author: Ćemal Dolićanin, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
74
Energy efficiency increasing of indoor swimming pools using solar technology
Dragoljub Živković, Marko Mančić, Peđa Milosavljević,
Milena Todorović, Dobrica Pejović, Bojan Stanković
Abstract: In this paper, preliminary energy balance of indoor swimming pools in the Sport and Recreation
Center “Dubočica” in Leskovac is performed. Energy efficiency analysis is done according to the results of
the performed analysis of energy balance. The most significant result of the preliminary energy balance
and energy efficiency analysis of indoor swimming pools is the proposal of measures for energy savings.
According to complexity and size of the investments required for their realization, proposed measures for
energy efficiency improvement are classified as: low‐budget, medium‐budget and high‐budget measures
of good housekeeping. Proposed high‐budget measures for energy efficiency improvement are based on
utilization of modern solar technology. Design and sizing of the system for heating sanitary hot water and
pool water is calculated using T*SOL Pro 5.0. The results show that installation of a solar thermal system
with 168 collectors type Viessmann VITASOL 200‐F SVE enable annual energy saving of 466.56 MWh, and
CO2 emission reduction of 100.78t.
Keywords: energy efficiency, indoor swimming pool, energy balance, solar technology.
Corresponding author: Dragoljub Živković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
75
Energy Efficiency Measures Implemented through Projects in Serbia
Dragan Pavlović, Pedja Milosavljević, Andjela Lazarević
Abstract: Energy efficiency is becoming a priority since it helps in reducing emission of greenhouse gas
and allows a reliable energy supply with significant energy savings. Energy consumption in Serbia is
relatively high, which is particularly evident in the public and residential sectors. In order to increase
energy efficiency in Serbia a set of systematic and well synchronized measures are necessary. There is
number of strategic documents and its action plans aimed to contribute to this target in Serbia. However,
a lack of systematic incentive measures, complex administrative procedures and bad economic situation
are the reasons that Serbia is still very energy intensive country. In recent years the number of energy
efficiency projects that have been implemented in Serbia increased, as a result of different public, private
and individual initiatives and increased awareness. Reducing energy consumption is a real long‐term goal.
This paper aims to summarize importance of energy efficiency, especially of the most demanding energy
sector which is the building stock sector, and also to present basic information about the projects that
have been realized in Serbia so far.
Keywords: Buildingstock, Energy efficiency, Energy balance, Energy consumption.
Corresponding author: Dragan Pavlović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
76
Calibrating Building Energy Models – “FBB” Building Case Study
Bratislav Blagojević, Marko Ignjatović
Abstract: Reducing energy consumption in buildings represents one of the greatest challenges in XXI
century. Serbia has adopted initial regulation considering building energy performance certification.
Detailed knowledge of particular building, systems serving it and energy flows within building boundaries
is needed in order to properly evaluate potential measures for reducing energy consumption. Use of
building energy simulation tools for new buildings in the design phase, as well as calibrated simulation for
existing ones is needed. In this paper, measurements for calibration of building energy model are
presented through the description of selected case study building: Feniks BB (FBB) combined office and
production building.
Keywords: Building energy model, Simulation, Model calibration, FBB building.
Corresponding author: Marko Ignjatović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
77
Energy Efficiency of an Elementary School “Prva Vojvođanska Brigada”
Dušan Savić
Abstract: Today, energy costs represent an increasingly important part of total costs. Cause on the one
hand, the increase in energy prices and energy prices due to objective reasons and speculators, on the
other hand more and more stringent environmental standards, which determine the use of more
sophisticated and more expensive power plants. The international community argues that irresponsible
human activities cause climate change (primarily greenhouse gas emissions) and to prepare for the future
radical programs to reduce energy consumption, reducing greenhouse gas emissions, increased use of
renewable energy and energy efficiency. For each factory and institution individually, it is necessary to
establish a system of cost management, measurement of relative energy efficiency of individual objects
and processes and permanent effect on the cost of energy. The rise in energy costs can have a significant
impact, and possibly increase the safety requirements, standards of living and more numerous and more
sophisticated computer equipment, and the introduction of energy management. In this paper a primary
school building, its construction characteristics, the structure of the envelope and its energy infrastructure
was shown. Also there were presented and analyzed current energy consumption, volume and energy
use, and proposed that all potentially valid measures and packages of measures to increase the energy
efficiency of the building as a whole.
Keywords: Energy, energy efficiency, energy audit, heat, infiltration.
Corresponding author: Dušan Savić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
78
Energy-Efficient Technologies Applied in Zero Energy Buildings
Suad Suljković, Velimir Stefanović, Saša Pavlović, Ivan Stojanović
Abstract: Today in the world there are a number of initiatives and low‐energy standards that promote
development of zero energy buildings. The complex concept of zero can be achieved in hot, moderate and
cold climates and energy efficient technologies are an important step towards achieving this goal.
This paper describes an energy‐efficient measures combined with passive and active techniques used in
zero energy buildings through examples of successfully completed projects and objects in different
climates.
Keywords: Energy efficiency, Optimization, Passive solar design, Zero energy buildings.
Corresponding author: Suad Suljković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
79
Analysis of the Natural Lighting and Energy Demand in the Student Dormitory
in Terms of Architectural Design
Petar Pejić, Dušan Petković, Marko Ignjatović, Sonja Krasić
Abstract: There are many reasons for the adequate use of natural light inside the dormitories. Studies
show that natural light has a great impact on people, their physical, physiological and psychological
health, and therefore the results achieved by each person. The intensity of light required for the student
activities and the temperature inside the room is one of the major factors for the occupant comfortable
work and life. They depend directly on natural lighting or otherwise electricity is used to achieve optimal
conditions. Design building facades in relation to the orientation has a significant impact on the use of
natural light. In this paper, a comparative analysis of student rooms with different orientations and
different façade’s designs was performed in order to investigate what type of refurbishment in the facade
only is necessary in order to maximize use of natural lighting.
Keywords: Architectural Design, Natural lighting, Eaves upgrading, Thermal Comfort.
Corresponding author: Petar Pejić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
80
Principles of design and construction of passive houses
Sanja Spasić
Abstract: The growing energy consumption and serious ecological crisis have caused increased focus on
renewable energy. In recent years, building of houses that promote the use of passive solar systems
became very often. The construction of such houses is more than desirable and advisable because of the
use of solar systems have enormous positive effects in reducing environmental pollution and energy
saving. The goal of this paper is to initiate the idea of the wide use of solar potential, based on the already
existing buildings and architectural examples from Europe and the world. This paper explores the
principles of design and construction of passive houses and also gives the examples from the world
practice.
Keywords: Solar energy, passive house, solar systems, architecture, energy efficiency.
Corresponding author: Sanja Spasić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
81
Application of passive solar systems in architecture
Sanja Spasić
Abstract: Because of the pollution of the environment on planet Earth, unreasonable attitude towards
resources and global warming, the need for using renewable energy sources grow higher and higher, with
a special emphasis on the global importance of solar energy. Passive use of solar energy is the basic and in
the same time the cheapest way of energy use.The main reason for that is the way how it works. It
doesn’t use any expensive technology but instead of that the design and construction of the structure has
to be adapted to maximum use of solar energy. The goal of this paper is to point out the importance of
using solar energy in architecture by showing the system which should be applied in the design of
buildings, as well as by analyzing each system individually.
Keywords: Solar energy, Passive solar systems, Architecture, Energy efficiency, Trombe‐misel wall, The
greenhouse.
Corresponding author: Sanja Spasić, e‐mail: [email protected]
7. Expert Systems
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
84
Governance of energy transition of non-residental buildings by policy intervention
Miroslav Kljajić, Dušan Gvozdenac, Jovan Petrović, Aleksandar Andjelković
Abstract: Starting on previous experiences, which are based on undertaken energy efficiency measures,
recorded unsatisfied indicators and trends in energy consumption, energy mix and the level of
environmental pollution, the necessity and priority of the new system changes is revealed, in the building
sector and the segment of existing non‐residential buildings. Despite many efforts, systematic and
organized care about energy efficiency in non‐residential buildings is missing and consequently the
improvements, which suggests the need for new approaches to governance the process of transition of
energy systems in buildings. The aim of this paper is to analyze and explore the most suitable energy
policy intervention for success in energy transition process in non‐residential building sector in Serbia.
Professional public, stakeholders, decision makers and creators of energy policies and strategies have
different and even opposite views on how to direct the process of transition of energy systems in
buildings, what type of instruments should to be used and how to evaluate the effects of changes. The
paper deals with tracing the pathway of energy transition process in existing non‐residential buildings as
an important segment of sectorial energy activities. The importance stems from the facts that the volume
of consumption of this category is significant (from 3.5 Mtoe of final consumption in Serbia, share of
building sector is 48% from which nonresidential buildings is up to 35%), that users are vulnerable social
groups, that worsening trends of energy efficiency are evidenced and consequently becoming excessive
financial burden on the local community and the state, that disturb the health of people and the
environment because they do not use clean energy technologies and a wrong attitude about energy in the
society is created because of inadequate valuation of energy as resource of the future. The paper is based
on energy indicators in Serbia, collected through energy audit techniques and analysis of official statistics.
Multiple Criteria Analysis (MCA) method is used for analysis of the intensity of key influences on the
success of energy transition process by implementation of the energy efficiency policy in Serbia and also
for results interpretation.
Keywords: Non‐residential Buildings, Energy Transition, Policy Intervention, Multiple Criteria Analysis.
Corresponding author: Miroslav Kljajić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
85
Energy systems and their use in public sector in Autonomus Province of Vojvodina
Igor Mujan, Aleksandar Anđelković, Jovan Petrović , Miroslav Kljajić
Abstract: Building sector represents one of the biggest energy consumers in European countries. Thus, the
facilities in the public sector have been in the focus of attention since they play a huge role in the building
sector energy consumption with the annually increasing energy demand and the absence of proper
energy management. The poor state of energy systems in public buildings and their inadequate operation
by the end user have driven the cooperative project between Faculty of Technical Sciences and the
Ministry of Education, Science and Technological Development on the extent of energy consumption in
the public sector which is in running for well over two years. This paper aims to present the results of the
work and define the current state and future needs of energy systems in buildings in relation to its users.
Three major parts of public building sector were covered: 22.6% of Education facilities in APV, 67.1% of
Medical facilities in APV and 58% of the Administrative sector (municipalities) in APV. The paper will show
the vast disparity between the Ordinance on energy efficiency of buildings issued in 2011 and the real
energy consumption in public sector as well as the outdated energy systems and their improper use.
Keywords: Energy Systems, Public Sector, Building, User.
Corresponding author: Igor Mujan, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
86
Risk Analysis Methods for Small Hydro Power Plants in Creating Insurance Policy
Andjela Lazarevic, Rade Karamarkovic, Vladan Karamarkovic, Dragoljub Lazarevic
Abstract: Small Hydro Power Plants provide more diversity in terms of financing projects, location
selection, ownership, its applications as well as insurance methods, comparing to the Conventional Hydro
Power Plants. Electricity produced by small hydro power plants could be used to improve energy
efficiency of different production facilities, domestic and public lighting and other applications. However,
those energy objects are exposed to the variety of risks that should be taken into consideration in
different ph ases of objects’ construction, operation and maintenance. Understanding of those risks is
crucial for undertaking of different techno‐economic analysis, as well as establishing of the insurance
policy for those power plants. The approaches used to create insurance policy for Small Hydro Power
Plants in certain countries depend of the technology applied and development level of the country and
will be provided in this paper.
Keywords: Small Hydro Power Plants, Energy Efficiency, Insurance Policy.
Corresponding author: Andjela Lazarevic, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
87
Optimization of Trigeneration Systems: A Combinatorial Metaheuristic Approach
Mirko M. Stojiljković, Mladen M. Stojiljković, Bratislav D. Blagojević
Abstract: On‐site energy supply systems with cogeneration and trigeneration are acceptable, convenient
and widely used solutions for increasing the efficiency of energy conversion, reducing pollution and
securing energy supply. In order to make these systems financially more attractive, more efficient or more
environmentally friendly, optimization of their structure, design parameters and operation is required. In
this paper, an approach to synthesis, design and operation optimization applicable primarily to the
systems for buildings energy supply is presented. Synthesis and design optimization is defined and solved
as a combinatorial problem, using genetic algorithms and particle swarm optimization, while optimal
operation regimes are determined using mixed integer linear programming, i.e. the branch‐and‐cut
method. This approach is applied to optimize structure, design and operation related parameters of a
trigeneration plant that could be used to supply a real residential settlement in Niš, Serbia. In this
example, only a financial objective function, i.e. annual total costs, is taken into account, although the
methodology might be used for other objective functions, as well as for multiobjective optimization.
Keywords: Cogeneration, Combinatorial optimization, Energy supply, Genetic algorithms, Mixed integer
linear programming, Particle swarm optimization, Trigeneration
Corresponding author: Mirko M. Stojiljković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
88
Cogeneration and Heat Storage in Optimized District Heating Plants.
Impact on Heat Costs and Primary Energy Consumption
Mirko M. Stojiljković, Goran D. Vučković, Dejan M. Mitrović
Abstract: Implementation of cogeneration and heat storage technologies in the district heating systems
might result with benefits related to efficiency, environmental impact, flexibility and security in heat
supply. Impact on finances, and consequently the cost of heat depends on many factors. In this paper,
potential for implementation of cogeneration together with heat storage in a typical small Serbian district
heating system is analyzed from the heat cost and primary energy consumption viewpoints. Several
models of cogeneration units are considered, in combination with various sizes of heat storage tanks. It is
assumed that the plant operates during heating seasons only and always in an optimal regime. In order to
determine the optimal operation regime, a mixed integer linear optimization problem is defined.
Keywords: Cogeneration, District heating, Heat cost, Heat storage, Mixed integer linear programming,
Optimization, Primary energy.
Corresponding author: Mirko M. Stojiljković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
89
Particle Swarm Optimization for the optimal tilt angle of solar collectors
Emina Petrović, Milica Jović, Vlastimir Nikolić, Dejan Mitrović, Mirjana Laković
Abstract: Solar energy will play an increasing important role in a future where reducing the dependence
on fossil fuels and addressing environmental issues are a priority. The energy technology sector is
experiencing marked change from its traditional architecture of large‐scale, centralized supply systems
that take advantage of significant economies of scale.
This paper deals with an optimum tilt angle and surfacing of solar collector. The annual optimum tilt angle
is dependent on many factors such as the weather condition. To find out optimum title angle of solar
collector in this work is used particle swarm optimization (PSO). The proposed methodology is shown to
successfully solve the problem.
Keywords: tilt angle, solar collectors, particle swarm optimization (PSO).
Corresponding author: Emina Petrović
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
90
Intelligent contemporary heating control of an amphitheatre
Žarko Ćojbašić, Milan Ristanović, Vlastimir Nikolić, Slavica Stojiljković, Nemanja Marković
Abstract: It is widely recognized nowadays that contemporary systems of building heating should be
designed in such manner that advanced central and local control is provided, which provides for both high
comfort and rational heating energy consumption. By the European standard „EN 15232 ‐ Energy
performance of buildings – Impact of Building Automation, Controls and Building Management“ building
automation, controls and building management systems that provide appropriate energy efficiency class
are demanded. In this paper such concept of control of heating system is presented through solution of
automation of high education institution amphitheatre, which provides for the highest energy efficiency
class A with contemporary concepts that provide comfort during system usage. Furthermore, such
sophisticated control systems are further empowered with intelligent functions based on application of
fuzzy and neural approaches, which add autonomous behaviour to the system that additionally stress user
friendliness and comfort. Control functions are presented along with description of proposed solutions,
while techno‐economic analysis is also briefly considered.
Keywords: Control, building automation, energy efficiency, heating, amphitheatre, computational
intelligence.
Corresponding author: Žarko Ćojbašić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
91
Intelligent Control System for Thermal Vision-Based Person-Following Robot Platform
Ivan Ćirić, Žarko Ćojbašić, Vlastimir Nikolić, Tomislav Igić
Abstract: In this paper the supervisory control of the Person‐Following Robot Platform is presented. The
main part of the high level control loop of mobile robot platform is a real‐time robust algorithm for human
detection and tracking. The main goal was to enable mobile robot platform to recognize the person in
indoor environment, and to localize it with accuracy high enough to allow adequate human‐robot
interaction. The developed computationally intelligent control algorithm enables robust and reliable
human tracking by mobile robot platform. The core of the recognition methods proposed is genetic
optimization of threshold segmentation and classification of detected regions of interests in every frame
acquired by thermal vision camera. The support vector machine classifier determines whether the
segmented object is human or not based on features extracted from the processed thermal image
independently from current light conditions and in situations where no skin colour is visible. Variation in
temperature across same objects, air flow with different temperature gradients, person overlap while
crossing each other and reflections, put challenges in thermal imaging and will have to be handled
intelligently in order to obtain the efficient performance from motion tracking system.
Keywords: Computational intelligence, Genetic optimization, Thermal Vision.
Corresponding author: Ivan Ćirić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
92
Classification of Mobile Objects According to Shape and Size
by Applying the Technique of Digital Image Processing
Aca Micić, Biljana Đorđević, Boban Andjelković
Abstract: Recognizing and classification of products on the conveyor belt accordingly to shape and size is
very significant in industrial processes. Economical solution of this problem implies the application of
standard industrial CCD camera, white diffuse light source and standard personal computer. The light
source gives away white diffuse light which is registered by CCD camera after the reflection from the
object surface and is being transmitted to the personal computer. Forming conditions of digital records
aren't always optimal, so they need to be processed in the most adequate way in order to make larger
quantity of informations more usable. Benefits of this method are: simple application of standard
techniques and commercial equipment, great reaction speed, contact‐less action and the possibility
includes large working surfaces in one single image. By using comparative analysis of the results obtained
with this method and results, obtained by already known methods, it's applicability can be confirmed.
Results of that research are shown in this paper.
Keywords: Digital image processing, Mobile object dimensions estimation, Pattern recognition.
Corresponding author: Biljana Đorđević, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
93
Non-linear contrast image enhancement
Biljana Djordjević, Boban Andjelković
Abstract: Precise notation of objects, processes and phenomena significantly affects the functionality of
mechatronical systems. Conditions, under which records of digital cameras are being realized, still aren't
optimal, so their quality needs to be improved in order to get a number of usable informations. In this
paper are presented few image filtering techniques, which contribute solving of this problem. Special
attention has been given to a group of non‐linear filters, which usage influences image contrast
modification and which obtains results that are applicable in real‐life situations. Several methods of image
contrast enhancing were analyzed: histogram equalization, adaptive histogram equalization, and method
of homomorphic filtering. Image contrast improvement and control of dynamical range are realized by
processing. Obtained results have been analyzed, estimation of original image quality and processed
image has been executed and their comparative analysis is given.
Keywords: non‐linear contrast enhancement, histogram equalization, adaptive histogram equalization,
homomorphic filtering, image quality estimation.
Corresponding author: Biljana Đorđević, e‐mail: [email protected]
8. Fluid Flow, Heat and Mass Transfer, and Combustion
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
96
Protective Measures Against Water Hammer
in a Long Pipeline Hydropower Plant with Pelton Turbine
Dragica Milenković, Dragan Svrkota, Milica Nikodijević
Abstract: Water hammer is an unsteady hydraulic problem which is commonly found in the penstocks of
hydropower plants. Due to either a malfunction of the system or inadequate operation conditions,
pipeline may collapse or burst. In this paper protective measures against water hammer problems in
hydropower plant Resavica with Pelton turbine are investigated. Water hammer phenomena have been
investigated as part of design process of new hydropower plant Resavica in Serbia. The small hydropower
plant Resavica is characterized by gross head of 186 meters, pipeline diameter DN800 and length of 7300
meters. Closure of the pipeline for Pelton turbine in the case of emergency shut‐down and load rejection
is modelled with closing of turbine main inlet valve, closing of the turbine needles, and combined closing
of turbine inlet valve with by pass valve. The results obtained with software developed by authors are
presented graphically and discussed.
Keywords: Long pipeline, Pelton turbine, protection, software, water hammer.
Corresponding author: Dragica Milenković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
97
Flow and Heat Transfer of Three Immiscible Fluids
in the Presence of Uniform Magnetic Field
Dragiša Nikodijević, Živojin Stamenković, Miloš Kocić, Milica Nikodijević
Abstract: The magnetohydrodynamic flow of three immiscible fluids in a horizontal channel with
isothermal walls in the presence of an applied magnetic field has been investigated in the paper. All three
fluids are electrically conducting, while the channel plates are electrically insulated. The general equations
that describe the discussed problem under the adopted assumptions are reduced to ordinary differential
equations and closed‐form solutions are obtained in three fluid regions of the channel. Separate solutions
with appropriate boundary conditions for each fluid have been obtained and these solutions have been
matched at the interface using suitable matching conditions. The analytical results for various values of
the Hartmann number, the ratio of fluid heights and thermal conductivities have been presented
graphically to show their effect on the flow and heat transfer characteristics.
Keywords: flow of immiscible fluids, heat transfer, Hartmann number, magnetic field.
Corresponding author: Dragiša Nikodijević, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
98
Influence of Water in Liquid Fuel on the Combustion Stability in Fluidized Bed
Milica R. Mladenović, Stevan Đ. Nemoda, Dragoljub V. Dakić, Milijana J. Paprika,
Ana D. Marinković, Branislav S. Repić, Mirko S. Komatina
Abstract: This paper presents results of the experimental and numerical investigation of fluidized bed
combustion of unconventional liquid fuels fed by the lateral jet. A special emphasis is given to influence of
water content in the fuel on the combustion parameters. During the combustion of the liquid fuels with
significant water content, a withdrawal of zone of the intense combustion below the bed surface was
registered. In the paper, it is explained by the assumption that the water in the fuel boosts mixing of the
fuel and the oxidizer. This assumption was confirmed by applying Euler two‐fluid model with kinetic
theory of granular flow. Numerical simulations have shown that the enhanced mixing of the fuel and the
oxidizer is caused by instantaneous transition of the water to steam and the expansion of the inlet jet, in
case of the fuels with high content of volatiles, or spraying of the liquid fuel to fine droplets, in case of the
fuels with low content of volatiles.
Keywords: Lateral jet, Fluidized bed, Unconventional liquid fuel, Water content.
Corresponding author: Milica R. Mladenović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
99
Influence of Burner Operating Parameters and Fuel Properties
On Pulverized Fuel Combustion
Branislav Repić, Dejan Djurović, Ana Marinković,
Aleksandar Erić, Goran Živković, Milica Mladenović
Abstract: Pulverized fuel firing is one of the wide modes of fuel utilization. For successful combustion of
pulverized fuel it is necessary to ensure adequate conditions by the appropriate choice of burners and
furnace characteristics. Combustion of pulverized fuel with swirl burners utilizing the swirl effects is very
significant and widely used. Swirl flows are used extensively because of their favourable influence on
stabilization and intensification of the combustion process and reduction of NOx emission. Optimal
operating conditions of pulverized fuel combustion depend on burner characteristics and fuel properties.
In the paper are presented the results of investigation of influence that constructive and operating
parameters of burner’s characteristics and fuel properties (biomass and coal) exert on pulverized fuel
combustion. Investigation of combustion of several types of fuels (biomass and coal) in swirl burner
models and prototypes were performed. Influence of the following parameters was investigated:
constructive parameters of burners (type, quarl), burner's operating parameters (velocity, temperature
and quantity of air, swirl number, excess air, concentration of pulverized fuel), and fuel properties (type,
quality, moisture, ash, volatile and combustible matters contents, pulverized fuel grinding fineness etc.).
Keywords: Burners, Pulverized fuel, Combustion, Biomass, Coal.
Corresponding author: Branislav Repić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
100
Combustion Experiments with Granular Biomass in a
Fluidized Bed Facility
Milica R. Mladenović, Stevan Đ. Nemoda, Dragoljub V.Dakić, Milijana J. Paprika,
Dejan M. Đurović, Branislav S. Repić, Srđan B. Uzelac
Abstract: Rational use of limited energy resources is an increasingly important topic, and biomass thereby
takes a special place. Subject of this paper is the combustion of granular biomass – corn kernels. A
detailed description of the demonstrational‐experimental boiler, power 300 kW, combusting
unconventional solid and liquid fuels in fluidized bed. The experimental results of the combustion of
granular biomass are presented, comprising temperature field along the furnace height, outlet flue gas
analysis, as well as the FB combustion parameters of the fuel. On the basis of the obtained results, an
assessment of the suitability of FB combustion of the granular biomass and its utilization for energy
purposes are given. This assessment especially important is having in mind the 2012 problem with the
aflatoxin contamination of the corn when just 32% of the harvests were safe for human food.
Keywords: Fluidized bed, Granular biomass, Corn, Combustion.
Corresponding author: Milica R. Mladenović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
101
Determination of a heat transfer coefficient for the back surface of a perforated plate
Mladen Tomić, Predrag Živković, Anica Milošević, Biljana Milutinović, Petar Đekić
Abstract: Numerical simulations were performed to determine heat transfer coefficient for back surface
of a perforated plate with square arranged cylindrical perforations. Three parameters were varied in the
study: plate porosity, pitch‐based Reynolds number and the fluid, while perforation diamter and plate
thicknes were constants. Plate porosity was varied in the range from 0.1 to 0.3 and for working fluid were
used helium, air, and carbon‐dioxide respectively. The Reynolds number was varied in the range from 50
to 7000. The Nusselt number was correlated in the function of Reynolds number, Prandtl number and
pitch‐to‐diameter ratio. On the end of the paper a comparison was done with other authors correlations.
The difference was found to be acceptable.
Keywords: heat transfer, perforated plate, pitch, porosity.
Corresponding author: Mladen Tomić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
102
Determination of a perforated plate convective heat transfer coefficient
for wide range of Prandtl numbers
Mladen Tomić, Mića Vukić, Predrag Živković, Gradimir Ilić
Abstract: Numerical simulations were performed to determine heat transfer coefficient of a perforated
plate with square arranged cylindrical perforations. Three parameters were varied in the study: plate
porosity, pitch‐based Reynolds number and the fluid, while perforation diamter and plate thicknes were
constants. Plate porosity was varied in the range from 0.1 to 0.4 and for working fluid were usedt helium,
air, carbon‐dioxide and water respectively, thus making the range of Prandtl number between 0.68 and 7.
The Reynolds number was varied in the range from 50 to 7000. The Nusselt number was correlated in the
function of Reynolds number, Prandtl number and pitch‐to‐diameter ratio. On the end of the paper a
comparison was done with other authors correlations. The difference was found to be acceptable.
Keywords: heat transfer, perforated plate, pitch, porosity.
Corresponding author: Mladen Tomić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
103
Research of Effectiveness of HHO Production for Use in Internal Combustion Engines
Miodrag Milenković, Miloš Milošević, Dušan Stamenković, Milan Pavlović
Abstract: HHO systems are designed to produce hydrogen and oxygen from water. The question is
whether and how much the combustion of fossil fuels in internal combustion engines can be enhanced
and complemented with such systems. There are several ways for producing HHO gas. In this paper one of
HHO systems, which uses electrolysis for obtaining HHO gas, is proposed. For electrolysis, the plates of
316L stainless steel with 15%‐ing aqueous solution of NaOH as the electrolyte were used. This research
was done in the function of obtaining a certain amount of gas under certain conditions: temperature of
generator, current, voltage, different frequency values and pulse width. Also, the required time for
obtaining one liter of HHO gas mixture was measured. This generator of HHO gas is composed of 13
panels of stainless steel 316L. With this configuration generator stands 1 liter of HHO gas per minute with
using of about 3 Wh of energy. At a constant current of I = 12.9 A, voltage of U = 26.9 V, 100% PWM pulse
width and 0.5 kHz of frequency, for 1 liter of HHO gas per minute, it was necessary to consume 2.852 Wh
of energy, while at a constant current of I = 9.8 A, a voltage of U = 27.8 V, 50% PWM pulse width and 0.5
kHz of frequency, for 1 liter of HHO gas per minute, it was necessary to consume 3.011 Wh of energy.
Keywords: Electrolysis, Generators of HHO gas, HHO gas, PWM.
Corresponding author: Miodrag Milenković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
104
Long-wavelength Marangoni instability
in a binary mixture layer with nonlinear Soret effect
Slavtcho Slavtchev, Penka Kalitzova-Kurteva, Alex Oron
Abstract: The thermodiffusion or Soret effect in binary systems is called nonlinear when the
thermodiffusive flux is proportional to the temperature gradient with a coefficient being linear function of
the solute concentration, instead of constant as for linear Soret effect. The nonlinear effect is mostly
pronounced in very dilute solutions and can be significant in some separation processes.
The report deals with the long‐wavelength Marangoni instability in a thin horizontal layer of a binary
mixture, subjected to a vertical constant temperature gradient. The layer is bounded by rigid plate from
below and free non‐deformable surface from above. It is heated from below and the free surface is
considered to be poorly conducting.
The nonlinear dynamic behavior of the liquid layer is studied in the case of monotonic instability. The
solution of the dimensionless equations of mass and momentum balances, heat transfer and mass
diffusion is presented near the linear stability threshold in the form of series in a small parameter that
measures the supercriticality above the threshold. A nonlinear equation for spatiotemporal evolution of
the system is derived. The bifurcation analysis of that equation for three kinds of patterns: rolls, squares,
and hexagonal patterns, reveals the conditions for their emergence and stability.
Keywords: bifurcation analysis, long‐wavelength instability, monotonic Marangoni convection, non‐linear
Soret effect.
Corresponding author: Slavtcho Slavtchev, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
105
Analysis of thermodynamic parameters in the injection mold with metal inserts
Saša Ranđelović, Saša Nikolić, Mladomir Milutinović
Abstract: The process of injection molding today is the widespread industrial technology market throws
an increasing number of finished products. Although the process depends on a lot of the large number of
technological parameters is necessary to continuously monitor key thermodynamic quantities, such as
temperature, pressure, speed, melt etc. that have a decisive influence to the quality of the finished part
and the productivity of the entire process. On the example of molding complex parts for wide use to
analyze the parameters of the process.
Keywords: Injection molding, Temperature filed, Pressure filed.
Corresponding author: Saša Ranđelović, e‐mail: [email protected]
9. Environmental Protection
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
108
Carbon Dioxide Emission from TPP Nikola Tesla A and B units
Zoran Marković, Milić Erić, Dejan Cvetinović, Predrag Stefanović, Vuk Spasojević , Predrag Skobalj
Abstract: Low‐calorific lignite from Kolubara open‐pit mines is mainly used for heat and power generation
in "Thermal Power Plants Nikola Tesla" ‐ TENT, Obrenovac. TENT is the largest electricity producer in
Serbia. TENT units are not equipped with adequate carbon dioxide emission monitoring systems for
continuous measurements. Since the CO2 emission by lignite combustion is the primary source of GHG in
Serbia (with a share of more than 40% in total GHG emission), the IPCC methodology suggests that the
calculation of CO2 emissions shall be based on the actual coal characteristics and not on the constant
value carbon emission factor CEF =27.6 [tC/TJ] as defined by the Tier 1 methodology. This paper presents
the results of measurement/calculation of carbon and carbon dioxide emission factors of Kolubara lignite
and specific emissions of carbon dioxide from four TENT A and two TENT B units, based on the results of
in‐situ measurements and detailed laboratory analysis of Kolubara lignite, flying and bottom ash samples,
collected during in‐situ measurements of carbon dioxide emissions from these units. Analysis of the
obtained experimental results have proved that carbon emission factor of the Kolubara raw lignite CEFr
with net (lower) calorific value Qdr in the range 6 ÷ 10 MJ/kg, can be represented by a linear correlation
CEFr [tC/TJ] = 34 407 ‐ 0.5891 Qdr [MJ/kg], giving the considerably higher values for CEFr than value
recommended by the IPCC Tier 1 methodology for lignite. The result of the measurements suggest higher
specific CO2 emissions values for small thermal power units with power of 200MW (units A1 and A2)
compared with specific CO2 emissions from units of 350MW (units A4 and A6) and 670MW (units B1 and
B2).
Keywords: Carbon dioxide emission, carbon emission factor estimation, Kolubara mine low‐calorific
lignite.
Corresponding author: Zoran Marković, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
109
Reduction of Particulate Matter Emission of the Upgraded Electrostatic Precipitators
at Unit B2 of the TPP “Nikola Tesla”
Milić Erić, Predrag Stefanović, Zoran Marković, Predrag Škobalj,
Nikola Živković, Vuk Spasojević, Dejan Cvetinović
Abstract: According to obligations, transposition of the Directive 2001/80/EC into state legislation have
been performed: Low on air protection (Sl. Glasnik RS br. 36/09) and the Directive on Limitation emission
values for the pollutants emitted in air (Sl. Glasnik RS br. 71/10) were adopted by the Parliament, while
Electric Power Industry of Serbia (JP EPS) as a socially responsible company have started with
reconstructions and modernization of the electrostatic precipitators on all their units since 2005. TPP
Nikola Tesla B performed reconstruction of the electrostatic precipitators at unit B2 with increased power
level, during 2011.
Paper presents results of the measurements of particulate matter concentration performed as a part of
guarantee investigations for the reconstructed electrostatic precipitators. Measurements were performed
in accordance with standards ISO 9096 and EN 13284‐1, by the Institute of Nuclear Sciences Vinča,
Laboratory for Thermal Engineering and Energy as an independent institution.
Keywords: electrostatic precipitator, emission, modernization, particulate matter, reconstruction.
Corresponding author: Milić Erić, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
110
Indoor air parameters measurements in kindergartens
located in different urban environments
Ivan Lazović, Sandra Stefanović, Žana Stevanović, Marija Živković,
Maja Đurović-Petrović, Žarko Stevanović
Abstract: Children require good indoor environment since indoor air quality is very important for their
growth and wellbeing. Since their educational process begins in kindergarten, they spend indoors
between 5 and 10 hours a day, wherefore the quality of air within the building is of crucial importance.
This study caries out indoor air quality measurements results, performed in two naturally ventilated
kindergartens. Buildings were chosen based on urban environment features. Environmental air quality
was the main reference for choosing these buildings. One of kindergartens is located in the industrial part
of Bor city. The second is situated within Belgrade worst traffic core. The measurements were obtained
during the winter heating period, and the results implied air temperature, relative humidity and carbon
dioxide concentration. The classroom average concentration of carbon dioxide often exceeded the value
of 1500 ppm during its full occupancy, which indicates inadequate ventilation. Analysis of measurements
also determined high correlation between humidity and carbon dioxide concentration. This fact may
constitute a solid basis for implementation of the fresh air supply strategy.
Keywords: indoor air quality (IAQ), environmental air quality (EAQ), carbon dioxide (CO2), relative
humidity (RH), temperature.
Corresponding author: Ivan Lazović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
111
The Environmental Indicators Related to Indoor Air Quality in Schools
Valentina Turanjanin, Biljana Vučićević, Marina Jovanović, Sandra Stefanović
Abstract: This paper presents set of environmental indicators of indoor air quality as a very important
component of indoor environment. The indoor air quality indicators are divided in three groups: physical
(temperature, relative humidity and Air Exchange Rates), gaseous (carbon dioxide, nitrogen dioxide,
ozone, formaldehyde, volatile organic compounds) and particulate (PM2.5 and PM10) IAQ indicators. The
indicators, formed for an elementary school in the urban area, are shown.
Keywords: Indoor Air Quality, Environmental Indicators, Schools, Sustainability.
Corresponding author: Valentina Turanjanin, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
112
Indoor Air Pollution Modeling of Belgrade Typical Dwelling
Sandra Stefanović, Marija Živković, Ivan Lazović, Žana Stevanović,
Maja Đurović-Petrović, Borislav Grubor, Žarko Stevanović
Abstract: The central concern of indoor air quality (IAQ) analysis is the prediction of airborne contaminant
dispersal in buildings. Airborne contaminants disperse throughout buildings in a complex manner that
depends on many parameters: the nature of air movements (in‐to, out‐of and within the building system),
the influence of the heating and natural ventilation, the possibility of removal by filtration or contribution,
by generation of contaminants etc. For IAQ analysis we seek to comprehensively model all of these
phenomena. The aim of this paper is to present methodology used for determination of airflow and
contaminant related phenomena. Subsequently, the goal was to model and investigate possible indoor
contaminant behavior as a result of implementation of building energy efficiency measures and GHG
emission mitigation scenarios. As a reference example representation, modeling and simulation
performance of one typical Belgrade dwelling has been performed. It incorporates developing of dwelling
idealization, schematic representation, defining its components, performing simulation and at the end
review of results.
Keywords: Indoor Air Quality, Contaminant behavior, Contaminant dispersal, Multi‐zone modeling.
Corresponding author: Sandra Stefanović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
113
AHP method for waste treatments ranking in terms of impact on the environment
Biljana Milutinović, Gordana Stefanović, Goran Vučković, Mladen Tomić, Petar Djekić
Abstract: When making the decision on the selection of appropriate waste treatment, one of the
important aspects is environmental protection. Different waste treatments have different effects on the
environment, which is expressed through a variety of environmental indicators. To assess the
environmental impact of a certain waste treatment, it is necessary to carry out an adequate analysis of all
influential environmental criteria. The main problem in the analysis is to determine the indicators that
clearly and fully sublimate the most important influential factors. The presented study was carried out on
the example of waste management in the city of Niš. Several scenarios of waste management have been
made. Three experiments were conducted in order to assess influence of environmental indicators: first
experiment was done using four indicators, second was done using seven indicators and third experiment
was done using ten indicators. The comparative results of scenario analysis are presented in this paper.
Ranking of each scenario was performed based on multi‐criteria analysis, the AHP method is used. With
the increasing number of environmental indicators it is shown that it is possible to make a clearer
difference between the waste treatments in terms of the impact on the environment.
Keywords: Multi‐criteria analysis, AHP method, Waste management, Environmental Indicators.
Corresponding author: Biljana Milutinović, e‐mail: [email protected]
16th Symposium on Thermal Science and Engineering of Serbia Sokobanja, Serbia, October 22–25, 2013
Society of Thermal Engineers of Serbia Faculty of Mechanical Engineering in Niš
114
Effective and Environmental Parameters of Diesel Engines
Using Biodiesel and Biodiesel – Petro Diesel Blends
Dame Dimitrovski
Abstract: This paper describes the basic mechanisms that lead to the thermal fatigue phenomenon.
Thermal fatigue is a process of damage origination and growth in machine parts and structural
components due to changes in internal energy caused by multiple cyclic or periodic changes of
temperature. This phenomenon is produced basically by cyclic or periodic temperature changes and
complete or partial restriction of thermal deformation. The restriction may be due to external or internal
factors. The results obtained so far suggest that thermal fatigue has much in common with creep and
mechanical fatigue. At this time it is not possible to present a complete general mechanism for damage
growth in thermal fatigue, so that further research is needed. This complex phenomenon requires further
research efforts. The aim of this paper is to highlight the thermal fatigue phenomenon, its importance and
consequences which these thermal stresses can cause. In this paper the main concepts which appear in
this field was mentioned and pointed out the importance of thermal stresses. Mechanisms of initiation
and propagation of the thermal fatigue cracks are also briefly mentioned.
Keywords: Thermal fatigue, Thermal stress, Crack propagation, Failure mechanism.
Corresponding author: Dame Dimitrovski, e‐mail: [email protected]
Mramor 18251, Mramorsko brdo bb
Tel 018‐694‐550; 018‐694‐054;
018‐694‐332; 018‐694‐551;
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Akcionarsko društvo HERZ Armaturen proizašlo je iz firme Gebauer & Lehrner, koja je osnovana davne 1896. godine . Tokom svog postojanja dugog 116 godina, kompanija se specijalizovala za proizvodnju i razvoj visokokvalitetnih armatura za grejanje, hlađenje i klimatizaciju. Na čelu kompanije u svojstvu vlasnika i Generalnog menadžera nalazi se g‐din Dr Gerhard Glinzerer. Danas je HERZ Armaturen GmbH, sa oko 1.500 zaposlenih, jedini austrijski i jedan od najvažnijih proizvodača termostatskih ventila, regulacione armature, sistema podnog grejanja, kotlova na pelet, solarnih sistema i toplotnih pumpi u Evropi.
Sedište kompanije HERZ Armaturen od 1986. godine je u novoj poslovnoj zgradi u Wien – Itzendorf, A‐1230, Richard‐Strauss Strasse 22. Ovde se nalaze proizvodnja armatura, centralni magacin i poslovno rukovodstvo. HERZ Armaturen u svom sastavu ima 8 fabrika i sve su u okviru Evropske unije: Austrija, Poljska, Rumunija i Slovenija.
Kompanija HERZ Armaturen ima predstavništva u skoro svim evropskim državama, na Bliskom Istoku, Severnoj i Južnoj Americi. Oko 60% proizvedene armatura se izvozi.
Trajni uspeh HERZ Armaturen zasnovan je na proizvodnom principu, da se samo tehnički zreli i visokokvalitetni proizvodi puštaju na tržište. Dugogodišnje iskustvo, kao i specijalizacija na polju grejne i regulacione tehnike, doprineli su razvoju brojnih inovativnih rešenja u sektoru uštede energije, kao i unapredjenju oblika i dizajna HERZ proizvoda.
HERZ ‐ termostatski ventili "DE LUXE" predstavljaju simbiozu visoke tehnike i luksuznog oblika i dizajna. Osim toga, HERZ Armaturen razvija zajedno sa poznatim evropskim sistemskim proizvođačima koncepte za uvođenje regulacione armature "krojene po meri" sa ciljem uštede energije i troškova grejanja.
HERZ Armaturen poseduje moderan sistem osiguranja kvaliteta u kome mnoge firme tesno sarađuju. HERZ proizvodi se stalno podvrgavaju ispitivanjima u internacionalnim i nacionalnim nezavisnim institutima. HERZ termostatski ventili odgovaraju Evropskoj Normi (EN215).
HERZ Armaturen u Srbiji, više od 20 godina, vrši prodaju preko svojih distributera.U 2003. godini otvoreno je predstavništvo za Srbiju, Crnu Goru i Makedoniju. Od maja 2009. godine, HERZ Armaturen ima svoj poslovno‐skladišni objekat na 1650 m², Industrijska zona bb, Nova Pazova.
U sklopu poslovnog objekta nalazi se magacin na 1200 m² i školski centar, gde inženjeri tehničke podrške permanentno vrše obuku za projektante i instalatere termotehničkih instalacija.
* Senzori* Termostati, presostati* Mikroprocesorski regulatori* Regulacioni ventili* Elektromotorni pokreta i* Izmenjiva
* Centralni sistemi
čči toplote
* Merila toplotne energije
AUTOMATIKAU FUNKCIJI
www.feniksbb.com
18000 Niš, Toponički put bb018 / 4575-556, 4575-557, 4575-33311000 Beograd, Ustanička 152/4
011 / 347-3978, 288-0926
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Tadeuša Košćuška 56 11000 Beograd Tel/fax: +381 11 6557 930; 6557 927
http:// www.viaocel.rs e-mail: [email protected] e-mail: [email protected]
Osnovna delatnost preduzeća VIA OCEL d.o.o. je inženjering termotehničkih i termoenergetskih postrojenja, što podrazumeva sve faze počev od izrade projektno tehničke dokumentacije, izvođenja radova pa do kasnijeg održavanja sistema, trgovina proizvodima crne i obojene metalurgije. U kratkom periodu VIA OCEL je zauzeo jednu od vodećih pozicija u ovim delatnostima i postao pouzdan partner zahvaljujući visokom kvalitetu svojih usluga.
NAJZNAČAJNIJE REFERENCE:
JKP BEOGRADSKE ELEKTRANE:
Modernizacija toplotnih podstanica za daljinsko grejanje, toplovodi i priključenja objekata,
rekonstrukcija toplane Konjarnik i Novi Beograd , izmenjivačka stanica TO Novi Beograd .
JP ELEKTROPRIVREDA SRBIJE ‐ TE NIKOLA TESLA, OBRENOVAC:
Proizvodnja grejnih površina, isporuka elemenata za pregrejače
i međupregrejače, izrada i isporuka ekonomajzera , izrada i
isporuka ulaznih i izlaznih komora pregrejača pare, izrada i
isporuka parovoda, izrada i isporuka radnih kola mlina za
ugalj ‐ N 400.42,kapaciteta 130t/h. TE KRAJOVA, RUMUNIJA Izrada i isporuka aksijalnih ventilatora dimnog gasa.
Preduzece Nova Yutkl doo Nis je generalni zastupnik Nova TKL doo Duga Resa Karlovac (nekadasnja" Jugoturbina") za prostore Srbije, BIH, i Crne Gore. Pretezna delatnost preduzeca je distribucija, nalevanje i izrada novih kliznih lezajeva koji se primenjuju u raznim oblastima industrije(na kompresorma, EM velike snage , reduktorima, pumpama), crnoj i obojenoj metalurgiji, rudarstvu(na mlinovima uglja, cementa i rude), energetici ( klizni lezajevi parnih i hidro turbina i generatora), brodogradnji (lezajevi na brodskim motorima) kao i remont reduktora raznih dimenzija i snaga.
Neki od vaznijih korisnika nasih usluga su HE Bistrica,HE Perucica, TE Kolubara, TE Gacko, TE Ugljevik, RTB Bor i mnogi drugi na ovim prostorima.
U saradnji sa firmom Inkla GmbH iz Austrije pored ove delatnosti Nova Yutkl je distributer zaptivnih materijala americke kompanijea GARLOCK (pletenice, ravne zaptivke, semeninzi za industriju i energetiku, EVSP setovi za zaptivanje na vretenima ventila i vratilima pumpi. PS zaptivke u prehrambenoj , farmaceutskoj i hemijskoj industriji. Takode smo isporucivali i mozemo da isporucujemo i opremu za Termo i Hidro elektrane Ruske proizvodnje kao i rezervne delove LMZ turbine i rezervne delove generatora ruske proizvodnje. Od nedavno smo poceli distribuciju i isporuku regulacionih ventila za paru i toplu vodu engleskog proizvodaca WEER.
S obzirom na siroku nasu delatnost koja je vezana pretezno za energetiku tj. Hidro i Termo centrale otvoreni smo smo za svaku vrstu saradnje i pozivamo sve zainteresovane da nam se obrate putem E‐maila na adresu: [email protected] .
Nova Yutkl doo Nis
Sasa Todorovic