Steady state and transient analysis of thermoelectric devices using finite element method

Thermoelectric devices offer noiseless and environment friendly operation, which makes them the most suitable devices of the future in their category. However, the performance of these devices is still way below its competitor thermal and electrical systems. The major factor that decides the performance of these devices is the thermoelectric material. Although the use of Silicon as a thermoelectric material greatly improved the performance of new thermoelectric devices over the metal based thermoelectric devices, it is still not close to the performance level of heat engines or refrigerators. With a limit on the material properties, these devices must be optimized based on all known effects that occur in the thermoelectric devices. The various effects that occur in a thermoelectric device are Seebeck effect, Peltier effect, Joule effect and Thomson effect. Most of the time, the design of thermoelectric generators and sensors is based on the steady state characteristics, which include only the governing thermoelectric effect (Seebeck effect) into the mathematical model. The Joule effect, Thomson effect and Peltier effect are historically assumed to have negligible influence on its performance characteristics. In this thesis, a complete steady state and transient model of thermoelectric generator is formed incorporating all the thermoelectric effects. The comprehensive model accounts for the internal heat generation inside the thermoelements due to the Joule effect and the Thomson effect. The Peltier effect is included as a plane heat source at the junctions that release heat in both directions. The model is formulated using finite element method, which is implemented into a computer program. The influence of different thermoelectric effects is studied under various working conditions. The use of finite element program, as a design tool for thermoelectric devices, is also demonstrated