Performance optimization for two-stage thermoelectric refrigerator system driven by two-stage thermoelectric generator

A new configuration of combined thermoelectric device, two-stage thermoelectric refrigerator driven by two-stage thermoelectric generator, is proposed in this paper. The thermodynamic model of the combined device is built by using non-equilibrium thermodynamic theory. The analytical formulae for the stable working electrical current, the cooling load versus the working electrical current, and the coefficient of performance (COP) versus the working electrical current of the combined device are derived. For the fixed total number of thermoelectric elements of the combined device, the allocations of the thermoelectric element pairs among the two thermoelectric generators and the two thermoelectric refrigerators are optimized for maximum cooling load and COP, respectively. The influences of the heat source temperature of the two-stage thermoelectric generator and the heat source (cooling space) temperature of the two-stage thermoelectric refrigerator on the optimal performance of the combined thermoelectric device are analyzed by detailed numerical examples.