Optimum variables selection of thermoelectric generator-driven thermoelectric refrigerator at different source temperature

Abstract

Based on the finite time thermodynamic model of thermoelectric generator-driven thermoelectric refrigerator with losses of external heat transfer, Joulean heat inside the thermoelectric device and the heat leakage through the thermoelectric couple leg, this paper analysed the effects of generator heat source temperature and refrigerator cooling temperature on the performance of the combined system using the combination of finite time thermodynamics and non-equilibrium thermodynamics. For a fixed total heat transfer surface area of four heat exchangers, the allocations of the heat transfer surface area among the four heat exchangers are optimised for maximising cooling load and the coefficient of performance (COP) at different source temperature of the combined thermoelectric refrigerator device, respectively. For a fixed total number of thermoelectric elements, the ratio of number of thermoelectric elements, i.e. the number of thermoelectric elements of the generator to that of the whole device is also optimised for maximising cooling load and the COP at different source temperature of the combined device, respectively. The change features of four design variables, i.e. the ratio of number of thermoelectric elements, the total heat transfer surface area ratio, the generator heat transfer surface area ratio and the refrigerator heat transfer surface area ratio are obtained, respectively. Moreover, optimum working electrical currents for maximum cooling load and COP at different total number of thermoelectric elements and different total heat transfer area are obtained, respectively.