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HVAC Guides
Heating, Ventilation and Air Conditionin System
http://electrical-engineering-portal.com/download-center/books-and-guides/hvac-guides
Introduction to HVAC
The goal for a HVAC (Heating, Ventilation and Air Conditioning) system is to provide proper air flow, heating, and cooling to each room. In this process HVAC systems can provide reduce air infiltration and maintain pressure relationships between spaces. In HVAC Industries there are so many standard organizations such as ASHRAE, SMACNA, ACCA, Uniform Mechanical Code, International Mechanical Code, and AMCA have been established to support the industry and encourage high standards and achievement.
Sometimes HVAC Design (heating, ventilation, air conditioning) systems have been compared to a mystical science, part alchemy, part religious ritual.
Following the basic steps of HVAC System Design:
Design HVAC systems for people living inside buildings, not for the buildings alone. You can’t fit a 24″ deep duct into a 23″ space, or, it’s the coordinated space
Be as fair as you can with and to all manufacturers
Dig deep into a given piece of equipment’s technical specs, and find nuggets of information that might save the owner and/or contractor money
Use nature to help your design
Have pity on the poor SOB’s that have to come behind you and service the system you design
In the end, only complaints or the lack of them matter
HVAC Process
In HVAC System, Ventilating is the process of replacing air in any space to control temperature or remove smoke, heat, dust and airborne bacteria. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings.
There are different types of standard heating process in HVAC system design. Central heating is often used in cold climates to heat residential houses and commercial buildings. Heating can also be provided from electric, or resistance heating using a filament that becomes hot when electricity is caused to pass through it. Air conditioning and refrigeration are provided through
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the removal of heat. An air conditioning system, or a standalone air conditioner, provides cooling, ventilation, and humidity control for all or part of a house or building.
All documents, software and books are free to download and preserved only to registered users. Login and registration links are located at the top-right of portal.
No. Description Download
1 Handbook of PE pipe
2 Fundamentals of air pollution engineering
3 GeoSource Heat Pump Handbook
4 Heat Exchanger and Boilers – Energy Conversion Guide
5 Primer on spontaneous heating and pyrophoricity
6 Recommendations for loop sizing, piping guidelines, piping arrangements
8 Thermodynamics Heat Transfer and Fluid Flow Handbook
9 User Guide for Desiccant Dehumidification Technology
10 Danfoss – The Heating Book
11 Refrigeration and air conditioning
12 Control Valve Handbook
13 Heating and Cooling With a Heat Pump
14 Ground-Source Heat Pump Project Analysis
15 Guide to Combined Heat and Power Systems
01 Handbook of PE pipeHandbook of Polyethylene (PE) Pipe
Published by the Plastics Pipe Institute (PPI), the Handbook describes how polyethylene piping systems continue to provide utilities with a cost effective solution to rehabilitate the underground infrastructure. The book will assist in designing and installing PE piping systems that can protect utilities and other end users from corrosion, earthquake damage and water loss due to leaky and corroded pipes and joints.
Piping applications
PE piping, has been successfully utilized for a variety of piping applications for over 50 years. Despite this relatively short history, the engineering community has embraced the overall toughness and durability of PE pipe and the latitude afforded by the variety of installation
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methods that can be employed using PE pipe to expandits use at a quickening rate.
Today, we see PE piping systems operating in a broad array of installations; from pressure-rated potable water and natural gas lines to gravity sewers, from industrial and chemical handling to telecommunications and electrical ducting; from oil and gas production to marine installations and directional drilling. This text has been developed to assist designers, installers and owners in the design, rehabilitation and installation of solid wall PE pipe. Applications using profile wall PE pipe are addressed briefly; applications using PEX pipe (for plumbing, heating, …) and applications using corrugated PE pipe (for drainage, …) are covered in multiple and separate PPI publications.
This Handbook discusses material properties, design, installation and applications of solid wall PE pipe and to a lesser extent, profile wall PE pipe. Corrugated PE pipe for drainage applications is covered in a separate handbook. This Handbook discusses material properties, design, installation and applications of solid wall PE pipe and to a lesser extent, profile wall PE pipe. Corrugated PE pipe for drainage applications is covered in a separate handbook.
The material presented in this text has been written in a manner that is easily understood, with an emphasis on organization to provide the reader with ease of reference. It is only because of our efforts to be as comprehensive as possible with respect to the subject matter that have resulted in such an extensive publication.
Content
Chapter 01 – IntroductionChapter 02 – Inspections, Tests and Safety ConsiderationsChapter 03 – Material PropertiesChapter 04 – PE Pipe and Fittings ManufacturingChapter 05 – Standard Specifications, Standard Test Methods and Codes for PE PipingChapter 06 – Design of PE Piping SystemsChapter 07 – Underground Installation of PE PipingChapter 08 – Above-Ground Applications for PE PipeChapter 09 – PE Pipe Joining ProceduresChapter 10 – Marine InstallationsChapter 11 – Pipeline Rehabilitation by Sliplining with PE PipeChapter 12 – Horizontal Directional DrillingChapter 13 – HVAC Applications for PE PipeChapter 14 – Duct and ConduitChapter 15 – General Guidelines for Repairing Buried PE Potable Water Pressure PipesChapter 16 – Pipe Bursting
Title: Handbook of PE pipe
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02 Fundamentals of air pollution engineeringControl air pollution
Analysis and abatement of air pollution involve a variety of technical disciplines. Formation of the most prevalent pollutants occurs during the combustion process, a tightly coupled system involving fluid flow, mass and energy transport, and chemical kinetics.
Its complexity is exemplified by the fact that, in many respects, the simplest hydrocarbon combustion, the methane-oxygen flame, has been quantitatively modeled only within the last several years. Nonetheless, the development of combustion modifications aimed at minimizing the formation of the unwanted by-products of burning fuels requires an understanding of the combustion process. Fuel may be available in solid, liquid, or gaseous form; it may be mixed with the air ahead of time or only within the combustion chamber; the chamber itself may vary from the piston and cylinder arrangement in an automobile engine to a lO-story-high boiler in the largest power plant; the unwanted byproducts may remain as gases, or they may, upon cooling, form small particles.
The only effective way to control air pollution is to prevent the release of pollutants at the source. Where pollutants are generated in combustion, modifications to the combustion process itself, for example in the manner in which the fuel and air are mixed, can be quite effective in reducing their formation. Most situations, whether a combustion or an industrial process, however, require some degree of treatment of the exhaust gases before they are released to the atmosphere.
Such treatment can involve intimately contacting the effluent gases with liquids or solids capable of selectively removing gaseous pollutants or, in the case of particulate pollutants, directing the effluent flow through a device in which the particles are captured on surfaces.
Title: Fundamentals of air pollution engineering
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03 GeoSource Heat Pump Handbook
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Heating and cooling
What is a heat pump? A heat pump is a mechanical device used for heating and cooling which operates on the principle that heat can be pumped from a cooler temperature to a warmer temperature (cold to hot). Heat pumps can draw heat from a number of sources, eg, air, water, or earth, and are most often either air-source or water-source.
Although heat pumps have been around for more than a 100 years, the technology has dramatically increased. Not only do heat pumps still operate the common refrigerator, but today, heat pump technology allows us to heat and cool residential and commercial buildings. Because of modem innovation, people using heat pumps are now able to save 50-70 percent on their annual heating and cooling costs.
Types of Heat Pumps
Air Source Heat Pump
The air source heat pump exchanges heat between the outside air and the inside air. When the outside air temperature is between 4O°F and 90°F these units are relatively efficient. However, as the temperature difference between the outside and inside air increases, the efficiency of the unit decreases. To overcome the loss of heating capacity these units require auxiliary electric heaters.
Water Source Heat Pump
The water source heat pump exchanges heat between water and the inside air. The water source heat pump is commonly used in commercial buildings using a boiler and cooling tower which keeps the loop water temperature between 60°F and 90°F. As a rule water source heat pumps have a lower operating cost but higher initial cost than air source heat pumps. This difference is due to water side costs of the system rather than air side cost.
Ground Source Heat Pump (GeoSource)
The GeoSource heat pump utilizes the earth as the medium from which heat is extracted. Water is pumped through a heat exchanger in the heat pump. Heat is extracted, and the water is then returned to the ground, either through discharge on a drain field or through a closed earth loop system. Because ground temperatures do not vary as dramatically as outside air temperatures, the heat available for transfer, as well as the unit’s operating efficiency remains relatively constant throughout the winter.
At depths of 15 feet or more below the ground, the soil maintains a year-round temperature of about 43°F -52°F in this region. So in the summer, it’s cooler than the outside air, and in the winter, it’s warmer–making it an ideal energy source.
Title: GeoSource Heat Pump Handbook
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04 Heat Exchanger and Boilers – Energy Conversion GuideOverview
This lecture deals with the practical use and applications of heat exchangers and boilers. These two appliances have much in common, since heat exchangers are vital parts of boilers, and in addition, boilers are the oldest and still one of the most common applications of industrial heat exchangers.
These two devices will be discussed separately, although. After an exposition of all different types of heat exchangers and examples of their usage, an overview about what has to be dealt with when one of these types needs to be installed and how to maintain it, will follow. After this, the same will be done for boilers.
Heat Exchangers
Heat exchangers can be described by reversing it’s two terms: they include all devices that are designed for exchanging heat. This is a very broad category of devices so first a restriction has to be made. Only heat exchangers that are meant to exchange heat between two fluids are taken into account. These fluids can be gasses as well as liquids.
It is still difficult to have an overview, and a classification needs to be made. It is possible to classify heat exchangers in a number of ways.
Title: Heat Exchanger and Boilers – Energy Conversion Guide
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05 Primer on spontaneous heating and pyrophoricity
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Abstract
The purpose of this Primer is to provide operations and maintenance personnel with the information necessary to identify and prevent potential spontaneous combustion hazards. Throughout the history of industry and the DOE Complex, fires caused by spontaneously heating and pyrophoric materials have occurred, sometimes causing personal injury and significant damage to facilities.
By its very nature, spontaneous heating and pyrophoricity are among the most insidious types of fire hazards. Many times there is no outward evidence of the potential for fires caused by these phenomena. An understanding of the principles of spontaneous heating and pyrophoricity is necessary for instituting fire prevention measures.
Combustion
Combustion (burning, or fire) falls into a class of chemical reactions called oxidation. Oxidation may be defined as the chemical combination of a substance with oxygen or, more generally, the removal of electrons from an atom or molecule. Oxidation reactions are almost always exothermic, or release heat. Many materials react with oxygen to some degree. However, the rates of reactions differ between materials.
The difference between slow and rapid oxidation reactions is that the latter occurs so rapidly that heat is generated faster than it is dissipated, causing the material being oxidized (fuel) to reach its ignition temperature. Once the ignition temperature of a material is reached, it will continue to burn until the fuel or oxygen is consumed.
The heat release during combustion is usually accompanied by a visible flame. However, some materials, such a charcoal, smolder rather than produce a flame.
Title: Primer on spontaneous heating and pyrophoricity
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06 Recommendations for loop sizing and piping guidelines
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Installation cost and efficiency
These residential closed-loop ground source heat pump (a.k.a geothermal or groundcoupled heat pumps) design guidelines were developed in conjunction with a project sponsored by the Tennessee Valley Authority in conjunction with a TVA Ground Source Heat Pumps promotion. Previous guidelines were verified and adjusted according to data gathered during this effort and previous similar projects.
A set of recommendations for loop sizing, piping guidelines, piping arrangements, and antifreeze precautions is provided. They attempt to balance the conflicting constraints of installation cost and efficiency.
These guidelines have recently been extended to regions beyond the TVA service territory.
Title: Recommendations for loop sizing, piping guidelines, piping arrangements
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08 Thermodynamics Heat Transfer and Fluid Flow HandbookFundamentals training
The Thermodynamics, Heat Transfer, and Fluid Flow Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of the thermal sciences.
The handbook includes information on thermodynamics and the properties of fluids; the three modes of heat transfer – conduction, convection, and radiation; and fluid flow, and the energy relationships in fluid systems.
This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility fluid systems.
Thermodynamic properties
Thermodynamic properties describe measurable characteristics of a substance. A knowledge of these properties is essential to the understanding of thermodynamics.
EO 1.1 DEFINE the following properties:
1. Specific volume2. Density
3. Specific gravity
4. Humidity
EO 1.2 DESCRIBE the following classifications of thermodynamic properties:
1. Intensive properties2. Extensive properties
Mass and Weight
The mass (m) of a body is the measure of the amount of material present in that body. The weight (wt) of a body is the force exerted by that body when its mass is accelerated in a gravitational field. Mass and weight are related as shown in Equation 1-1.
Title: Thermodynamics Heat Transfer and Fluid Flow Handbook
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10. Danfoss – The Heating Book
8 steps to control of heating systems
Heating a home has always been and still is a basic human requirement. This requirement enables us to live and work in locations with low temperature. In the beginning the solutions were simple. An open fire on the floor of a tent or a simple hut, made it possible to survive in a hostile environment. As civilisation developed there was migration from the countryside to the towns and cities and into bigger and bigger houses, creating a requirement for more elborate heating systems.
This requirement stimulated technical development, but also created a problem, namely the use of a finite resource (fossil fuels) with the resulting pollutions from the burned fuels.
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Company profile
Danfoss A/S and its subsidiaries engage in the research, development, production, sale, and service of mechanical and electronic components and solutions worldwide.
It offers refrigeration and A/C products, including compressors, condensing units, appliance controls, thermostatic expansion and solenoid valves, pressure and temperature regulators, thermostats and pressure controls, water valves, filter driers and sight glasses, industrial refrigeration control solutions, stop and regulating valves, safety valves, line components, liquid level and electronic controls, electronically operated valves, sensors and transmitters, accessories and spare parts, and brazed plate heat exchangers.
The company also provides heating products, which consist of radiator and room thermostats, floor heating hydronics and electrical products, climate controls, substations, weather compensators and PI controllers, motorized control valves, pressure and flow controllers, temperature controllers, heat exchangers, ball and balancing valves, burner components, heat
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meters, ventilations, pressure and temperature switches, heat pumps, and solenoid valves; and VLT drives, which include frequency converters, decentral products, soft starters, and power options. In addition, it offers industrial automation products, such as externally and thermostatically operated valves, vacuum valves, coils for valves, single and dual pressure switches, differential pressure and temperature switches, pressure transmitters, temperature switches, temperature sensors, contactors and motor starters, electronic soft starters, and accessories and spare parts.
Danfoss has released this great heating book in 9 chapters which are available on this page.
All documents, software and books are free to download and preserved only to registered users. Login and registration links are located at the top of the portal or use links below.
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No. Danfoss – The Heating Book: 8 steps to control of heating systems Download
1 Part 1-Definitions
2 Part 2-Control of heating systems used in Western Europe
3 Part 3-Secondary systems used in Europe
4 Part 4-Evaluation of systems and products
5 Part 5-Instructions for designing district heating systems
6 Part 6-Instructions for designing heating systems
7 Part 7-How to select size of products and components
8 Part 8-Technical data, formulas and charts
9 Formulas – for the calculation and dimensioning of heating products
10.1. Definitions
District heating
District heating is a kind of system which provides a number of buildings with heat generated from a central boiler plant through pre-insulated pipes. (Pre-insulated pipes are in fact a modern
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kind of heat culvert or district heating duct, but since these systems nowadays are pre-manufactured, they will from here on be referred to as pre-insulated pipes.)
The smallest systems cover 200-300 houses or a block. The connection to the secondary heating system can be direct or indirect, i.e. with or without a heat exchanger. Domestic hot water is also produced with the help of district heating. As a result, the heating plants are also in operation during non-heating seasons. There is a difference between heating plants, pure heat producers and combined heat and power plants. The main purpose of the last-named
s to produce electricity through a steam turbine. The connected buildings are used to cool down the condensate to such a low temperature as possible in order to increase the capacity of the steam turbine.
The efficiency for coal-fired power plants is low, 30-40 %. By combining the power production with the heat delivery, the efficiency has increased right up to 90 %, which corresponds to the efficiency of well-kept district heating plants.
District heating plant
A district heating plant, (the primary circuit), can be divided into three parts:
Production (central boiler plant) Distribution (pre-insulated pipes)
Consumption (sub-station)
In the production plant, the water temperature is increased to the required level. Distribution implies heat transfer to the consumers with as small a loss as possible. Consumption implies heat transfer from the water of the primary side to the water of the secondary side, and a large temperature drop in the primary water. It may also imply directly connected systems, detached houses for instance, with a differential pressure control as protection against too high differential pressures.
District heating systems with a large production plant, an efficient distribution network and a sub-station with heat exchanger and automatic controls, can be made very effective in respect of consumption as well as pollution.
The choice of material and operating conditions such as static pressure, temperature and water quality are important factors concerning the operation of the system, its maintenance and its durability. The heating system in a building, (the secondary circuit), can be divided into three parts:
Production (heat transfer through the heat exchanger) Distribution (the main piping system of the building, including the circulation pump)
Consumption (radiators, convectors, or floor heating for the rooms)
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In the production plant, the secondary water temperature is increased to the required level. Distribution implies heat transfer to the consumers with the smallest losses possible and small temperature drop. Consumption implies heat transfer from the water to the rooms and large temperature drop in the water.
Title: 8 STEPS – CONTROL OF HEATING SYSTEMS – Part 1-Definitions
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10.2. Control of heating systems used in Western Europe
Environmental requirements
The environmental requirements on fuel are made more and more stringent. The contents of environmentally hazardous substances in coal and oil have diminished considerably during the past ten years.
There are also requirements on the volume of dust discharges of the ashes after good combustion. In cases where the requirements made on the fuel cannot be fulfilled, a penalty tax is imposed, and/or a plant reducing the environmental influence to the established level is requested.
The pollutants, set free by the combustion, are spread with the winds covering very large areas. It is not sufficient only to limit the discharges locally, but the same requirements are necessary all
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over Europe. Certain values have been established and a tightening-up of the requirements will be carried out, as people in many countries find the values too high.
Sulphur causes acidification of the ground which kills both plants and animals. Nitrogen also causes acidification and have negative effects on the ozone layer. Both these substances travel great distances and measures must be taken right at the source. Opposite, are allowed discharges according to IEA Coal Research air pollutant emission standards for coal-fired plants database, 1991.
Hydrocarbons derived from motor-driven vehicles and industrial processes contribut to the fact that ozone is formed close to the ground and the fact that the ozone layer is demolished. Greenhouse gases, carbon dioxide, nitrous oxide and methane are all contributing to the so-called greenhouse effect. Carbon dioxide is formed by different sorts of combustion, in central heating plants, in car engines etc. Heavy alloys, which influence the germ plasm, are stored all the time, and gradually they end up at the top of the food chain, i.e. in predators and in human beings.
Fuel
Oil and coal are the fuels most frequently used. Natural gas is more and more used as well as biofuel (renewable energy such as forest waste and straw).
Coal is refined through washing so that the content of pollutants and ashes will be less than before. The sulphur content is under 0.8 %. By spraying with surface chemicals or with water only, the dust amount from transport and handling has been reduced. Pulverized coal is a processing operation that increases the efficiency of handling and combustion. Efficient purification of the exhaust gases is required, bearing in mind solid particles, sulphur and nitrogen gas.
Because of the large volumes in connection with district heating, the transport must be carried out by ship, unless of coal mine is located near the district heating plant.
Oil for large district heating systems, so called heavy oil, contains a maximum of 0.8% sulphur and can be very efficiently burnt with present techniques, but to reduce the discharges to the accepted level, purification of the exhaust gases is required. The oil is tranported by ship and lorry or by train. Gas can be purified from possible pollutants before combustion, but nitrogen remains even after the combustion. When dealing with large quantities in liquid form, transport is undertaken by special tankers or through gas pipe-lines.
Biofuel is mostly used in minor plants, up to 10.000 apartments, 700.000 m2. Biofuel is not considered to have negative effects on the environment, as the carbon dioxide, released by the combustion, is used when the corresponding amount of biofuel is building up.
Title:8 STEPS – CONTROL OF HEATING SYSTEMS Part 2 – Control of heating systems used in Western Europe
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10.3. Secondary systems used in Europe
Lower pressure
Secondary systems are the parts of the heating systems with a lower pressure and temperature level, installed in buildings. A lower pressure and a lower temperature can be obtained with a shunt connection and a differential pressure control, (direct connected systems). The most commonly used system is, however, the connection through a heat exchanger, completely separating the two systems from each other, (indirect connected systems).
The secondary systems consist of three parts:
production, boiler or heat exchanger distribution
consumption
When speaking of district heating, the production unit is in fact only atransformation from one temperature- and pressure level to another, but regarding function, it is a production unit.
Comfort
The purpose of the heating system is to create environmental conditions in the building, comfortable for people to live in. Generally an air temperature of 20-23 ºC is considered acceptable, butthere are also other factors influencing the comfort:
the temperature of surrounding surfaces air movements, convection
activity level
clothing
The heat transfers which we can influence, towards and from a person in a room, are from radiation, convection and/or conduction. A minor share comes from breathing. Heat transfer by radiation has the biggest influence. We are receiving heat from surfaces with a higher temperature than our skin, and we are emitting heat to surfaces with a lower temperature.
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The greater difference the larger the heat transfer. Air with a lower temperature that flows over a surface removes heat from the surface. The higher velocity of the air-flow the more heat is removed. The greater the temperature difference the larger the heat flow. Heat conduction requires direct contact, for instance when you are sitting on a cold chair, but it is normally short-lived as the chair is quickly warmed up by your body heat. The result of the factors mentioned above and the temperature of the room air at a given point in a room, can be calculated.
It is thus possible to determine in advance if a heating system will provide an acceptable comfort in a given room. Surface temperatures close to 20 ºC on all surfaces in a room and air-flow velocities lower than 20 cm/s provides very good comfort.
Title: 8 STEPS – CONTROL OF HEATING SYSTEMS Part 3 – Secondary systems used in Europe
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10.4. Evaluation of systems and products
Vertical or horizontal systems
Vertical radiator systems imply that the riser is laid at an outer wall, and that one, maximum two radiators per floor are connected to the riser. There are two important disadvantages with this system. For one thing, there are many risers conducting noise between the apartments.
Secondly, when using one-pipe systems there are problems in how to limit the number of radiators per one-pipe circuit. One as well as twopipe systems can be used. There are also difficulties insulating the risers placed visually in the rooms. Horizontal radiator systems imply that several apartments on the same floor share a riser, how many depending on the planning. The riser can, in this case, be laid centrally in the house and be insulated so that allfloors obtain the same flow temperature.
The piping to the radiators is installed horizontally on a wall or embedded in the floor and can be installed separately for each apartment as well as for multiples. When using two-pipe systems, there is the possibility of metering the flow to the radiators in each apartment and also keeping the available differential pressure constant on each floor. The disadvantage is the laying of the pipes to the radiators. Horizontally laid pipes on a wall by the floor or by the ceiling are neither pretty to look at nor hygienic, and near the floor cause problems if doors are to be passed. The casting of pipes into floors requires that the floor construction is made in two steps, one bearing construction, upon which the pipes are laid and one screed laid after having pressure tested the pipes.
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Embedded pipes ought to be insulated and require such conditions that they do not need to be exchanged until the building has served its time. One- as well as two-pipe systems can be used.
Centrally placed risers and horizontal laying to the radiators are advantageous, above all when constructing a new building, but this can also be made in existing buildings. Some advantages are:
a smaller number of risers no noise transfer between the apartments
the possibility of flow metering per apartment
differential pressure control for each floor
small radiator circuits reducing the requirement of adjusting
Title: 8 STEPS – CONTROL OF HEATING SYSTEMS Part 4 – Evaluation of systems and products
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10.5. Instructions for designing district heating systems
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Effect ranges
Local district heating systems should lie within the range of 40-60 MW. The effect refers to the actual heat requirement in the buildings. The combined heating and power plant should deliver about 60% of the total connected heat requirement, at optimum distribution between electricity (40%) and heat production (60%). Minimum output, electricity and heat, is to be 200 MW.
The local heating plants should be connection to a combined heating and power plant only be used at peak loads and at operational break down and maintainance the combined heating and power plant.
Existing boilers
Existing boilers, of 40-60 MW, in good condition that do not need to be exchanged within a reasonable time, should use coal with a low content of ashes, the combustion should be made with a high efficiency. Flue gas coolers should be installed to raise the effictively and then the condensate, SOx must be taken care of effectivly. The boilers should be in operation night and day and turned off only for cleaning.
Flue gas purification with bag filter should be installed, and as maintenance work is required, other measures should be taken for a change-over to the supply from a combined heating and power plant.
In principle, the same procedure applies on both smaller and larger boilers, but the smaller ones should be removed as soon as possible, and their system is to be connected to larger plants with flue gas purification.
New boilers
When new boilers are installed, either in new or existing district heating networks, the out put should be of about 40-60 MW, the combustion should be made with a fluidised bed. The coal quality has to be good, i.e. low contents of sulphur and ashes, and the combustion should be done continuously as long as there is any need of it. Two or more local heating plants of this size can at an early stage be connected to preinsulated pipes. It is better to have one heating plant with a capacity of 100% in operation, than to have three with a capacity of 33% each.
The discharges of SOx and NOx stays at an acceptable level with this combustion technique, even without purification. When the local heating plants are later connected to the combined heating and power plant, the operation times will be reduced to perhaps 15-20% per year, the SOx -and NOx levels are then acceptable.
The discharges of particles must be limited. This is done by using bag filters.
Title:8 STEPS – CONTROL OF HEATING SYSTEMS – Part 5 – Instructions for designing district heating systems
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10.6. Instructions for designing heating systems
Pressure control of pumps
All the circulation pumps in systems with varying flow should be equipped with pressure control. A constant differential pressure at the last branch/valve provides the largest saving.
Using pressure control doesn’t mean that differential pressure control valve should be excluded.
Control of the available differential pressure
In buildings of maximum 6 floors, each riser is equipped with a differential pressure control providing 10 kPa. When the building has more than 6 floors, a differential pressure control, providing 10 kPa, should be installed on each floor.
Flow metering per apartment / Heat
Each apartment is equipped with a flow meter for the distribution of the heating costs. The flow meter should be accessible for reading from the stair-well, and possibly connected with the control and supervision system of the building. With regard to gable apartments and apartments with a roof, a compensating factor is calculated on the basis of heat requirement calculations made for a similar apartment in the centre of the building.
Domestic water system.
Domestic hot water is produced in a heat exchanger of the percolation type in the sub-station. A distribution pipe is laid in the ground floor of the building, from which risers are drawn up centrally through the building. Each riser is equipped with shut-off and draining valves.
The branches on each floor are equipped with shut-off valves. Distribution pipes and risers should be made of a non-corrosive material and well insulated. A gravity pipe for the of hot water should be laid parallel to the tap waterpipe.
The circulation pipe should be laid uninsulated in the riser, and at the connection with the horizontal circulation pipe be equipped with an adjustment valve. Flow meters for domestic hot
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water should be installed in the stair-well,one for each apartment.
Title:8 STEPS – CONTROL OF HEATING SYSTEMS – Part 6 – Instructions for designing heating systems
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10.7. How to select size of products and components
Choice of thermostatic valve size / Existing one-pipe systems
All the radiators must be equipped with thermostatic valves to be able to control the room temperature, use the incidental heat gain efficiently and distribute the heat according to requirements. This requires a by-pass at each radiator, and the resistance in the by-pass has to be larger than in the main pipe so that a certain amount of water is let to in the radiator.
Good operation is obtained if the thermostatic valve has a low resistance, like valves intended for gravity circulation, and the by-pass is of the same dimension as the main pipe. The by-pass is equipped with a restriction creating the required resistance.
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Two-pipe systems
The valve size is determined on the basis of the required flow and the available differential pressure. Maximum differential pressure is limited to 25 kPa as far as noise is concerned. The available differential pressure for each thermostatic valve is obtained from the pipe calculation.
Flow
The flow is calculated from the heat requirement in watts, W, and the temperature drop across the radiator in Kelvin, K. The valve size can then either be determined from a selection flow chart or be calculated.
Valve size
The last valve in the design circuit, (which determines the pump head throughout the entire system) ought to have a resistance of about 5 kPa.
The other valves should be sized according to the differential pressure available for them, i.e. the penultimate valve in the design circuit has an available pressure equal to the resistance across the last valve plus the resistance in the pipes between the two valves.
Title:8 STEPS – CONTROL OF HEATING SYSTEMS – Part 7 – How to select size of products and components
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10.8. Technical data, formulas and charts
Content Diagram for local district heating plants and heating and power plant Diagram for heating and domestic hot and cold water
Heat emission from radiators
Conversion chart for radiators in one-pipe systems
Reduction of heat emission from radiators
Heat losses from uninsulated pipes
Pressure drops in steel pipes
Resistance in heating systems
Sizes of steel pipes for heating systems
Flow chart for thermostatic radiator valves in one-pipe system
Flow chart for thermostatic radiator valves in two pipe system
Flow chart for Δp control valves for risers or circuits
Flow chart for control valves in heating systems
Flow chart for control valves in district heating systems
Flow chart for Δp control valves in district heating systems
Heat requirements for domestic hot water
Flow limiters for one-pipe circuits
Calculation of one-pipe systems
Calculation of two-pipe systems
SI-units, Greek alphabet, Physical properties for water
Title:8 STEPS – CONTROL OF HEATING SYSTEMS – Part 8 – Technical data, formulas and charts
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10.9. Formulas for the calculation of heating products
Abstract
Danfoss has gathered the most common formulas for the calculation and dimensioning of heating products in a table to give you a quick overview of the at times complex formulars we use in the heating business.
Flow rate Mass flow rate
Kv value
Kv values in parallel
Kv value in series
Differential pressure from Kv value
Differential pressure from tete value
…
Title:8 STEPS – CONTROL OF HEATING SYSTEMS – Formulas – for the calculation and dimensioning of heating products
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11. Refrigeration and air conditioningPrinciples of equipment cooling
You have studied the fundamentals and commercial refrigeration and air-conditioning systems. This final volume deals with another phase of your career ladder-equipment cooling. Since the principles of equipment cooling are common to all refrigeration systems, your mastery of the subject should be easy. All of the systems covered in this volume can be applied to commercial refrigeration and air conditioning.
To qualify you in equipment cooling, we will present the following systems in this volume:
Direct expansion Absorption
Centrifugal
Water treatment
Centrifugal water pumps
Fundamentals of electronic controls
Electronic control
JUST WHAT DO we mean when we say “direct expansion”? In the dictionary we find that the word “direct” means an unbroken connection or a straight bearing of one upon or toward another; “expansion” relates to the act or process of expanding or growing (in size or volume). Now we can see that a direct expansion system for equipment cooling is one in which the controlled variable comes in direct contact with the single refrigerant source, thereby causing the liquid refrigerant to boil and expand.
The centrifugal and absorption systems differ in that that they us a secondary refrigerantwater or brine-to cool the variable.
Title: Refrigeration and air conditioning (equipment cooling)
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12. Control Valve Handbook
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What Is A Control Valve?
Process plants consist of hundreds, or even thousands, of control loops all networked together to produce a product to be offered for sale. Each of these control loops is designed to keep some important process variable such as pressure, flow, level, temperature, etc. within a required operating range to ensure the quality of the end product.
Each of these loops receives and internally creates disturbances that detrimentally affect the process variable, and interaction from other loops in the network provides disturbances that influence the process variable. To reduce the effect of these load disturbances, sensors and transmitters collect information about the process variable and its relationship to some desired set point. A controller then processes this information and decides what must be done to get the process variable back to where it should be after a load disturbance occurs.
When all the measuring, comparing, and calculating are done, some type of final control element must implement the strategy selected by the controller. The most common final control element in the process control industries is the control valve. The control valve manipulates a flowing fluid, such as gas, steam, water, or chemical compounds, to compensate for the load disturbance and keep the regulated process variable as close as possible to the desired set point.
Many people who talk about control valves or valves are really referring to a control valve assembly. The control valve assembly typically consists of the valve body, the internal trim parts, an actuator to provide the motive powerto operate the valve, and a variety
Title: EMERSON Process Management – Control Valve Handbook
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13. Heating and Cooling With a Heat PumpIntroduction
If you are exploring the heating and cooling options for a new house or looking for ways to reduce your energy bills, you may be considering a heat pump. A heat pump can provide year-round climate control for your home by supplying heat to it in the winter and cooling it in the summer. Some types can also heat water.
In general, using a heat pump alone to meet all your heating needs may not be economical. However, used in conjunction with a supplementary form of heating, such as an oil, gas or
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electric furnace, a heat pump can provide reliable and economic heating in winter and cooling in summer.
If you already have an oil or electric heating system, installing a heat pump may be an effective way to reduce your energy costs.
Energy Management in the Home
Heat pumps are very efficient heating and cooling systems and can significantly reduce your energy costs. However, there is little point in investing in an efficient heating system if your home is losing heat through poorly insulated walls, ceilings, windows and doors, and by air leakage through cracks and holes.
Title: Heating and Cooling With a Heat Pump
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14. Ground-Source Heat Pump Project Analysis
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Background
Maintaining a comfortable temperature inside a building can require a significant amount of energy. Separate heating and cooling systems are often used to maintain the desired air temperature, and the energy required to operate these systems generally comes from electricity, fossil fuels, or biomass.
Considering that 46% of sun’s energy is absorbed by the earth as shown in Figure 1, another option is to use this abundant energy to heat and cool a building.
In contrast to many other sources of heating and cooling energy which need to be transported over long distances, Earth Energy is available on-site, and in massive quantities.
Because the ground transports heat slowly and has a high heat storage capacity, its temperature changes slowly—on the order of months or even years, depending on the depth of the measurement. As a consequence of this low thermal conductivity, the soil can transfer some heat from the cooling season to the heating season as presented in Figure 2; heat absorbed by the earth during the summer effectively gets used in the winter.
This yearly, continuous cycle between the air and the soil temperature results in a thermal energy potential that can be harnessed to help heat or cool a building.
Title: Ground-Source Heat Pump Project Analysis
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15. Guide to Combined Heat and Power Systems
Integration of Cogeneration Technology
The guide is organized into topics that address many of the fundamental issues encountered in planning a CHP project and focuses on technical subjects associated with the integration of cogeneration technology into new and existing ICI boiler installations. As discussed in Chap. 1, successful integration of cogeneration technology into new or existing ICI boiler installations involves technical and economic screening followed by detailed engineering design.
To assist boiler owners and operators avoid excessive outlays while evaluating the viability of cogeneration technology, the guide discusses technical, economic, and regulatory issues that should be considered during the planning phase of any CHP project.
In addition, the guide identifies many of the potential benefits and possible barriers to successful implementation.
Use of this information will help answer the following important questions.
1. Is cogeneration technically feasible?2. Is cogeneration economically feasible?
3. Can strategies be developed for overcoming barriers to implementation?
Information presented in Chap. 2 addresses a variety of cogeneration technology issues to serve as a foundation for subsequent discussions. Descriptions and schematics of topping- and
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bottoming-cycle thermodynamic processes are presented because they represent the two fundamental heat-recovery schemes commonly used in industrial CHP applications.
Discussions in Chapter 2 also focus on existing energy and environmental regulations that influence the way CHP systems are designed and operated.
Requirements in these regulations can affect the economic viability of a project because emissions control equipment needed for environmental compliance generally adds to the cost of a CHP system. Other important issues covered in Chap. 2 include benefits of cogeneration technology, the various operating modes that can be employed to achieve a particular strategic objective, and a summary of the major barriers to implementation.
Understanding the fundamentals of cogeneration technology, being aware of federal laws and regulations that affect CHP construction and operation, and knowing the barriers to implementation are essential to evaluating CHP viability.
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Guide informationTitle: Guide to Combined Heat and Power Systems – C. B. Oland
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