Performance optimization of a two-stage parallel thermoelectric cooler with inhomogeneous electrical conductivity

A new concept of inhomogeneous thermoelectric materials is advanced recently. In the present study, a novel two-stage thermoelectric cooler (TEC) in electrically parallel configuration is investigated. It is made of the inhomogeneous materials with space-dependent electrical conductivity. The internal irreversibilities of the thermoelectric cooler are taken into account. The temperature profile and heat flux in the thermoelectric legs are derived. Thermal rectification can be realized through the modification of the constant properties model which can result in higher cooling capacity and coefficient of performance (COP). The optimal operating regions are explored. Furthermore, the ratio of thermocouples between two stages, the area-length ratio of legs and cold side temperature have significant effect on some important performance characteristics. In the case of optimal ratio of thermocouples between two stages and optimal area-length ratio of legs, coefficient of performance and cooling capacity rise 22.6% and 28.9% respectively by using inhomogeneous materials.