High efficiency solar thermophotovoltaic system

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HIGH-EFFICIENCY SOLAR THERMO-PHOTOVOLTAIC

SYSTEM

GUIDED BYMr. NITHIN ROY VAsst professor Mechanical Department

PRESENTED BY:Aswin Jaladhar

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1. Introduction

2. Relevance of TPV

3. Parts of TPV

4. Working of TPV

5. Efficiency

6. Micro-cavity effect

7. Applications

8. Advantages

9. Conclusion

10. Reference

CONTENTS

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Solar thermo photovoltaic cells are used to convert solar energy and heat energy in to electrical energy

Now a days Thermo Photo Voltaic cells are used for combined power generation

Henry Kolm had constructed an elementary TPVsystem at MIT in 1956

Pierre Aigrain is widely cited as the inventor of TPV

INTRODUCTION

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WHY THERMO-PHOTOVOLTAIC

SYSTEMS?• The available energy from the sun is as low as 1 kw/m2• No solar energy is available at the night• And also on cloudy and rainy days• The efficiency of solar systems are very less(11-15 %)• It can also be used as a heat recovery system

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1. HEAT SOURCE

2. EMITTER

3. FILTER

4. ARRAY OF PHOTO VOLTAIC CELLS

A TPV SYSTEM CONSISTS OF

Source : http://newenergyandfuel.com/wp-content/uploads/2011/07/MITs-New-ThermoPhotoVoltaic-Cell.png

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• The primary source is the sun• Heat from a boiler• Waste heat from plants• Chimneys of factories• Waste heat from auto mobiles

HEAT SOURCE

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May be broadband or selective Selective only allows a single wavelength Recently at Sandia Labs have demonstrated a high-efficiency (34% )

TPV emitter using tungsten photonic crystals

PROPERTIES• Thermal stability

• Corrosion resistant

• Shock resistant

• High thermal conductivity

EMITTER

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• To prevent the entry of photons without a specified energy

• For blackbody emitters or imperfect selective emitters, filters are needed to reflect non-ideal wavelengths back to the emitter.

• Any light that is absorbed or scattered and not redirected to the emitter or the converter is lost.

• Both can lead to inefficiencies.

FILTER

Source : Spectrally Controlled Thermal Radiation Based on Surface Microstructures for High-Efficiency Solar Thermophotovoltaic system

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• In order to convert the thermal energy into electrical energy

• The effect of influence of Zn diffusion profiles in a p-GaSb emitter on the characteristics of GaSb PV cells was observed.

• The optimum depth of the p-n junction has been found allowing increase theefficiency

THERMO-PHOTOVOLTAIC CELLS


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• Heat energy is fed to the emitter• It emits radiations according to the input• A filter is placed to transmit only the

radiations of desired wavelength• This filtered radiations is allowed to fall

on the PV cells• PV cells produces electricity accordingly • PV cells are cooled using a separate

cooling system

WORKING……..


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• Carnot efficiency

ᶯ = 1- < 80 % (usual case)

EFFICIENCY

At T cell = 300k T emit = 1600k

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• It means we have to convert all the photon(available energy) should be converted

• Reflectors are placed behind the converters• By using selective emitters • Using more efficient filters• Photon recycling

HOW WE CAN IMPROVE THE EFFICIENCY ?

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• In order to increase the efficiency of the emitter

• Micro cavities are made on the surface of emitter

• Two types of micro cavities are there

• open-end micro-cavity

• Closed-end micro-cavity

• Closed end micro-cavity has more emissivity than open

• The micro-cavity is covered by a semi-transparent metal film

• The cavity a covered by a thin layer of Au to enhance the performance of the TPV cell

MICRO-CAVITY EFFECT


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• The amount of power generated by a PV depends on the operating voltage of the array

• A set of operational conditions, cells have a single operating point where the values of the current (I) and voltage (V) of the cell result in a maximum power output.

• This is known as the maximum power point (MPP)

• A PV’s maximum power point (MPP) varies with solar insulation and temperature

• At the MPP, the PV operates at its highest efficiency

MAXIMUM POWER POINT TRACKING

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• The energy is stored when available

• Energy is stored in the form of latent heat in a PCM

• The commonly used PCM is NaF

• NaF uses this heat for phase change

• When we need it ,heat is extracted from the NaF

• But the efficiency of the system will be less working in NaF

• The main thing is that we get power even there is no source available

TPV CELLS WITH STORAGE

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• Distributed combined heat and power generation

• In the automotive sector in case of hybrid vehicles

• Glass or other high temperatures industries

• TPV system has been proposed for portable generators

• Co-generation systems

• Combined cycle power plants

• Military

• Space

APPLICATIONS

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• Can be used as off grid generators• Already implemented in North America and other developing countries• Provide un interrupted power supply in winter and night times• Fuel flexibility when compared to other systems• Best alternative to the present day system

COMMERCIAL APPLICATIONS

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• First TPV car

• 2 seated race car.The battery charge is maintained by a Thermophotovoltaic generator

• Funding for the TPV generator and the vehicle was from a US Department of Energy (DOE) grants in concert with an industry partner, JX Crystals of Issaquah, WA.

• Final installation and finishing was supported by the MURI Dept. of Defense grant.

• The 8 kW generator makes use of gallium antimonide photovoltaic cells surrounding a central emitter heated by a compressed natural gas flame to 1700 Kelvin.

• The infrared photons generated activate the photovoltaic cells to produce electricity.

• The electric motor is a Unique Mobility 75 kW (100 HP) motor which is 95% efficient through most of the operating regime..

VIKING 29A THERMO-PHOTOVOLTAIC SERIES ELECTRIC HYBRID

Source : http://www.wwu.edu/vri/images/v29_8.jpg

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High fuel utilization factor (close to the unity)

TPV system as a combined heat and power system

Low produced noise levels (due to the absence of moving parts)

Easy maintenance(similar to a common domestic boiler)

Great fuel flexibility(natural gas ,oil ,coke , nuclear fuels)

TPV system usually allows very low pollutant emissions (e.g. CO and NOx)

Low installation & maintenance cost

Uses only less space

ADVANTAGES

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• The efficiency of the present thermo-photovoltaic system is 80%

• Micro cavity effect helps to increase the efficiency of system

• By using the above methods it can be brought up to 86%

• It can be used as the heat recovery systems there by increasing the overall efficiency of plant

• It can be used in hybrid vehicles as a power source

• It can be used a portable power source

CONCLUSION

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1. Asaka Kohiyama, Makoto Shimizu, Hiroaki Kobayashi, Fumitada Iguchi, Hiroo Yugami “Spectrally Controlled Thermal Radiation Based on Surface Microstructures for High-Efficiency Solar Thermophotovoltaic system” Graduate School of Engineering, Tohoku University, Energy Procedia 57 (2014 ) 517 – 523

2. C. Ferraria, F. Melinob, M. Pinellic, P. R. Spinac, M. Venturini ‘‘Overview and Status of Thermophotovoltaic Systems” 68th Conference of the Italian Thermal Machines Engineering Association, ATI2013 Energy Procedia 45 ( 2014 ) 160 – 169

3. Peter Bermel, Michael Ghebrebrhan, Walker Chan, Yi Xiang Yeng, Mohammad Araghchini,Rafif Hamam, Christopher H. Marton “Design and global optimization of high-efficiency thermophotovoltaic systems” Department of Physics, Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, MA 02139, USA 13 September 2010 / Vol. 18, No. 103 / optics express

4. Mohamed Al Hosani & Mahieddine Emziane, ‘‘Modeling and Simulation of a Thermophotovoltaic Systemwith NaF Heat Storage” , The Mediterranean Green Energy Forum 2013, MGEF-13 Energy Procedia 42 ( 2013 ) 726 – 734

REFERENCE

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Education

High efficiency solar thermophotovoltaic system