Performance investigation of thermoelectrics with an external spacer inserted in serious

This study consists of two parts: mathematical modeling for the start-up period (transient system) and an optimum design analysis of a thermoelectric cooler (TEC). In the mathematical modeling for the transient system, a dimensionless time to reach the steady state is determined, which can be practically adopted to reduce the start-up period during the operation of a thermoelectric module (TEM). The objectives of the optimum design analysis are to investigate the effect of key parameters characterizing the TEC on the coefficient of performance (COP) and to determine the optimal conditions for the TEC design. It is found that the COP increases up to 44% with an increase of the ratio of heat transfer area of the insulator to that of the TEM, γ. For micro-TEC, the COP is significantly affected by the TEM depth and spacer. Especially in the case of TEM depth of 100 μm, the COP is enhanced up to 110% at an optimal spacer depth ratio (ε - 1) of 10. The results show that the effect of figure of merit Zm (= S² / R K_TE) on the COP appears differently according to the combination of thermal conductance K_TE, electric resistance R and Seebeck constant S of the TEM. It reveals that when a new thermoelectric material is developed, the optimal combination among K_TE, R, and S as well as Zm should be considered simultaneously.