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  2. 2. 2  Introduction  Basic Principle of TEG  Applications  Advantages  Disadvantages  Conclusion  Reference OVERVIEW THERMOELECTRIC GENERATOR
  3. 3. INTRODUCTION  Energy crisis-main problem.  Increased pollution & population.  Tremendous energy wasted in the form of heat.  Constant uninterruptable power requirement.  Distorts the output performance.  Efficiency decreasing in electronic systems.  Increased interest in renewable energy.  Energy scavengers are modern trend. SOLUTION???SOLUTION??? THERMOELECTRIC GENERATORSTHERMOELECTRIC GENERATORS 3 THERMO ELECTRIC GENERATOR
  4. 4. 4 Fig.1 Energy Statistics THERMO ELECTRIC GENERATOR
  5. 5. WHAT IS TEG??  Devices that convert temperature differences into electrical energy.  Basic principle – “SEEBECK EFFECT” (power generation).  PELTIER EFFECT ( Heating and cooling purposes) 5 Fig. 2 TEG Module THERMO ELECTRIC GENERATOR
  6. 6. Working principle of TEG Seebeck effect 6 Fig. 3 Working Principle THERMO ELECTRIC GENERATOR N-Bi2Te3 P-Sb2Te3
  7. 7. THERMO ELECTRIC POWER GENERATION  It is based on SEEBECK EFFECT.  Heat is applied to a circuit at junction of different conductors a current will be generated.  THOMAS JOHANN SEEBECK invented Seebeck effect in 1822.  The Magnitude of voltage generated is proportional to temperature difference and depended on type of the conducting material  Seebeck coefficient defined as the open circuit voltage produced between two points on a conductor when a uniform temperature difference of 1k is applied between those points. 7
  8. 8. Thomas Johann Seebeck [ 1770 – 1831 ] 8 Figure 4
  9. 9.  The simplest thermo electric generator consist of thermocouple of n type and p type elements connected electrically in series and thermally in parallel.  heat is input from one side and rejected from other side.  a voltage will be generated across Thermocouple.  The magnitude of the voltage is proportional to the temperature gradient. 9 Figure 5
  10. 10. Seebeck Effect 10 Figure 6
  11. 11. THERMO ELECTRIC HEATING AND COOLING  These are based on PELTIER EFFECT  That is current is passes through a two dissimilar conductors there will be a rise or fall of temperature at junction depending on direction of current flow  Peltier effect discovered by Jean Peltier in 1834  Electrons moved from p type to n type, material absorbing thermal energy from cold junctions.  Electrons dump their extra energy at hot junction as they flow from n type to p type material through electric connector. 11
  12. 12. Jean Peltier [ 1785 - 1845 ] 12 Figure 7
  13. 13. Peltier Effect 13 Figure 8
  14. 14. FABRICATION OF TEG  Highest performance can be obtained in presence of heavily doped semiconductor such as Bismuth and silicon germanium.  TEG must be a) Small in size b) Light in weight c) High silicon compatibility. 14 Figure 9
  15. 15.  Fabrication process of thermo electric microconverters 1. The p type Sb2te3 film is deposited by thermal co-evaporation followed by Nickel 2. Photo resist and P type elements are patterned by photolithography. 3. Nickel is etched in chromium etchant, a Thermoelectric film is patterned by wet etching HNO3.HCL and photo resist is removed. 4. The n type film deposited by co evaporation followed by 100m nickel layer. 5. Photo resist is applied and patterned by photolithography for n type element. 6. N type is etched in HNO3 and photo resist is removed, contacts are deposited starting with a layer of nickel followed by 1µm of aluminum and photo resist is removed. 7. A protective layer of Si3N4 can also be deposited by low-temperature hot wire chemical vapor deposition and patterned depending on application. 15
  16. 16. 16 Figure 10
  17. 17. FIGURE OF MERIT  The performance of thermoelectric devices depends on the figure of merit (ZT) of the material , which is given by Where, α- Seebeck coefficient, ρ - the electrical resistivity, λ - the thermal conductivity, and T – the temperature 17 THERMO ELECTRIC GENERATOR  A good thermal material must have 1. High Seebeck coefficient, 2. Low electric resistivity, 3. Low thermal conductivity.
  18. 18. CALCULATION • For a single thermo couple  Open circuit voltage V = ( @ * dT) ……….. (1) • @ – Seebeck coefficient= dV/dT (volt/Kelvin ) • dT – diff in temp = Th-Tc (Kelvin)  Current through the load, I= @ * DT ……….. (2) Rc+RL • RL – load resistance • Rc – internal resistance 18
  19. 19. 19  Efficiency of the generator (Eg) is: Eg = V x I ..............(3) Qh • The total heat input to the couple = Qh T c = Temperature at cold junction T h = Temperature at hot junction
  20. 20. 20 Applications Wireless EEG Fig.18 Wireless EEG THERMO ELECTRIC GENERATOR
  21. 21. 21 Thermoelectric micro converter Power conditioning Ultra low power EEG amplifiers Signal processing and control RF CMOS transceiver @2.4GHz Block Diagram of TEG -EEG system Figure 19 Block diagram
  22. 22. • Human body temperature 270 c to 360 c • Forehead & Nose have little high temperature • Epilepsy or Sleep monitoring • Patient while doing exercise • Regular medical data automatically recorded • Comfort for the subject ( human or animal ) • No need to replace or recharge the battery 22
  23. 23. • Air conditioner business developed recently • CFC emission increased • Alternative should be found out • Peltier effect is being used • Beneficial to use because 1. Low maintenance 2. Long life 3. No moving parts 4. Can be used for microchip cooling 23 TEG for Cooling Figure 15
  24. 24. Low power devices such as wrist watches and hearing aids 24 Fig.16. Thermic watch THERMO ELECTRIC GENERATOR
  25. 25.  Easy to use  Maintenance free  Long life  Good for daily use  Uninterruptable power so no risk  Watches were first brought by SEIKO & CITIZEN 25 Figure 17 thermic watch by SEIKO
  26. 26. Automotive thermoelectric generators fig 11 TEG in the exhaust of an automobile THERMO ELECTRIC GENERATOR 18
  27. 27. 27 Figure 12
  28. 28. 28 Thermo Electric Generator stove Figure 13
  29. 29. 29 Thermoelectric Phone Charger Figure 14
  30. 30. Advantages  Solid state construction, no moving part, no vibration.  Available 24 hours a day.  No noise and low maintenance.  Convenient power supply.  Stabilize temperature of devices.  Increase operation life under all environment.  Space and military applications.  Performance output highly scalable.  Waste Heat – Electricity.  Space requirement is only 1/20th of a solar cell.  Portable power.  Less weight than a battery. 30 THERMO ELECTRIC GENERATOR
  31. 31. Disadvantages  Low efficiency.  High cost.  High output resistance.  Adverse thermal conditions. 31 THERMO ELECTRIC GENERATOR
  32. 32. 32 Conclusion THERMO ELECTRIC GENERATOR  TEG to supply low power electronics ( milli watts).  Waste heat conversion to useful energy beneficial to present energy crisis.  Numerous advantages over disadvantages.  Variety of application field.  Introduction of nanotechnology.  Development in future will lead to interesting applications.
  33. 33. E e-books available Google 1. Waste Energy Harvesting: Mechanical and Thermal Energies • By Kong Ling Bing, Tao Li, Huey Hoon Hng, Freddy Boey, Tianshu Zhang, Sean Li 33
  34. 34. Reference [1] Joao Paulo Carmo,Luis Miguel Goncalves and Jose Higino Correia, “Thermoelectric microconverter for energy harvesting systems”, IEEE transactions on industrial electronics, VOL. 57, NO. 3, march 2010 [2] Tom Torfs, Vladimir Leonov, Refet Firat Yazicioglu,Patrick Merken, Chris Van Hoof,” Wearable Autonomous Wireless Electro-encephalography System Fully Powered by Human Body Heat”, IEEE SENSORS 2008 Conference. [3] L.M. Goncalves and J.G. Rocha,” Application of Microsystems Technology in the Fabrication of Thermoelectric Micro-Converters”, Solid State Circuits Technologies, Book edited by: Jacobus W. Swart. [4] Tianqi Yang, Jinsheng Xiao, Wenyu Zhao, Qingjie Zhang,”Structural Optimization of Two-stage Thermoelectric Generator for Wide Temperature Range Application”,2011 IEEE. [5] Xiaodong Zhang, C.C. Chan, and Wenlong Li,” An Automotive Thermoelectric Energy System with Parallel Configuration for Engine Waste Heat Recovery”, IEEE trasactions on industrial electronics 2010. [6] Luciana Wasnievski da Silva,and Massoud Kaviany,” Fabrication and Measured Performance of a First-Generation Microthermoelectric Cooler”, Journal of microelectro mechanical systems,VOL. 14, NO. 5,october 2005. [7] Design and Fabrication of Heat Storage Thermoelectric Harvesting Devices M. E. Kiziroglou, Member, IEEE, S. W. Wright, T. T. Toh, P. D. Mitcheson, Senior Member, IEEE,Th. Becker and E. M. Yeatman, Fellow, IEEE 2012 34 THERMO ELECTRIC GENERATOR