thermo electric generators

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  1. 1. @T SHANMUKHA REDDY ON 22/03/17 SEEBECK PELTIERWILLIAM THOMSON
  2. 2. Contents 1. Seebeck effect 2. Peltier effect 3. Joule Thomson effect 4. Thermo-electric effect 5. Thermo-electric generators
  3. 3. The Seebeck effect is a phenomenon in which a temperature difference between two dissimilar electrical conductors or semiconductors produces a voltage difference between the two substances. This was discovered by German physicist Thomas Seebeck (1770-1831).
  4. 4. When heat is applied to one of the two conductors or semiconductors, heated electrons flow toward the cooler one. If the pair is connected through an electrical circuit, direct current (DC) flows through that circuit.
  5. 5. The voltages produced by Seebeck effect are small, usually only a few micro volts per Kelvin of temperature difference at the junction. Numerous devices can be connected in series to increase the output voltage or In parallel to increase the maximum deliverable current.
  6. 6. Seebeck Coefficient: The voltage produced between the two points on a conductor when a consistent temperature difference of 1o Kelvin is maintained between them is termed as Seebeck coefficient. One such combination of copper constantan, has a see beck coefficient of 41 micro-volt per Kelvin at room temperature.
  7. 7. The Peltier effect is a phenomenon in which temperature difference created by applying a voltage between two electrodes connected to a sample of semiconductor material. This was discovered by Jean Charles Peltier. This phenomenon can be useful when it is necessary to transfer heat from one medium to another on a small scale. Peltier effect is converse of Seebeck effect. French physicist JEAN CHARLES PELTIER
  8. 8. Peltier Coefficient: Peltier coefficient is defined as the amount of heat energy absorbed or evolved due to peltier effect at the junction of two dissimilar metals when one coulomb of charge passes through the junction. Peltier coefficient is denoted by . Value of Peltier Coefficient is different for different thermo-couple . Its value also depends upon the temperature of the junction.
  9. 9. Thomson effect is the phenomenon in which the generation or absorption of heat in a current carrying conductor with a temperature gradient. A phenomenon discovered in 1854 by William Thomson, later Lord Kelvin. LORD KELVIN (WILLIAM THOMSON)
  10. 10. Thomson showed that the Peltier heat or power (Qp) at a junction was proportional to the junction current (I) through the relationship Qp = I, where is the Peltier coefficient. Thomson coefficient: Through thermodynamic analysis, Thomson also showed the direct relation between the Seebeck and Peltier effects, namely that = T, where T is the temperature of the junction(Thomson coefficient)
  11. 11. The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa. A thermoelectric device creates voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, it creates a temperature difference. The term "thermoelectric effect" encompasses three separately identified effects: the Seebeck effect, Peltier effect, and Thomson effect.
  12. 12. Applications: To measure temperature using thermo electric thermometer. To detect heat radiation using thermopiles. Thermoelectric refrigerator or generator. (A thermopile is an electronic device that converts thermal energy into electrical energy.)
  13. 13. ---------------------------------------------------------------- A thermoelectric generator (TEG), also called a Seebeck generator. A thermo electric generator is a device which converts heat (temperature differences) directly into electrical energy through a phenomenon of thermo electric effect (Seebeck, Peltier, Thomson effects)
  14. 14. Advantages Easy maintenance: They works electrically without any moving parts so they are virtually maintenance free. Environment friendly: Thermoelectric generators produce no pollution. Therefore they are eco friendly generators. Compact and less weight: The overall thermoelectric cooling system is much smaller and lighter than a comparable mechanical system. High Reliability: Thermoelectric modules exhibit very high reliability due to their solid-state construction
  15. 15. Applications:

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