Chapters authored
Performance Analysis of Composite Thermoelectric Generators
Composite thermoelectric generators (CTEGs) are thermoelectric systems composed of different modules arranged under various thermal and electrical configurations (series and/or parallel). The interest for CTEGs stems from the possibility to improve device performance by optimization of configuration and working conditions. Actual modeling of CTEGs rests on a detailed understanding of the nonequilibrium thermodynamic processes at the heart of coupled transport and thermoelectric conversion. In this chapter, we provide an overview of the linear out-of-equilibrium thermodynamics of the electron gas, which serves as the working fluid in CTEGs. The force‐flux formalism yields phenomenological linear, coupled equations at the macroscopic level, which describe the behavior of CTEGs under different configurations. The relevant equivalent quantities—figure of merit, efficiency, and output power—are formulated and calculated for two different configurations. Our results show, that system performance in each of these configurations is influenced by combination of different materials and their ordering, that is, position in the arrangement structure. The primary objective of our study is to contribute new design guidelines for development of composite thermoelectric devices that combine different materials, taking advantage of the performance of each in proper temperature range and type of configuration.
Part of the book: Thermoelectrics for Power Generation
Thermodynamic Analysis of Thermoelectric Legs with Different Geometric Parameters
The design of thermocouple legs is the central theme of this chapter, the methodology of reduced variables is shown, which allows the designer to obtain the dimensions of the geometric parameters, specifically the cross-sectional areas transversal An, Ap and length of the legs ln=lp. The main quantities used within this scheme calculation method are the reduced current density U, the thermoelectric potential Φ, and the thermal conductivity κ. Subsequently, the performance of the designed thermocouple is analyzed through the electrical power produced when the system is connected to an electrical resistance load. In this step, the condition of the dependence of thermoelectric properties on temperature is used. The results show specific values of the cross-sectional areas in which the maximum power value occurs. Although the main method has the advantage that it uses minimal computing and software requirements, a spreadsheet may be sufficient for the calculations. It is also important to mention that in addition to calculating the dimensional parameters, the technique allows the generation and evaluation of various designs for the same temperature range.
Part of the book: Novel Applications of Piezoelectric and Thermoelectric Materials