Effect of heat transfer on the performance of two-stage semiconductor thermoelectric refrigerators

A model of two-stage semiconductor thermoelectric refrigerators with external heat transfer is proposed. The performance of the refrigerator obeying Newton's heat transfer law is analyzed using the combination of finite-time thermodynamics and nonequilibrium thermodynamics. Two analytical formulas for cooling load versus working electrical current, and the coefficient of performance (COP) versus working electrical current, are derived. For a fixed total heat transfer surface area of two heat exchangers, the ratio of the heat transfer surface area of the high-temperature-side heat exchanger to the total heat transfer surface area of the heat exchangers is optimized to maximize the cooling load and the COP of the thermoelectric refrigerator. For a fixed total number of thermoelectric elements, the ratio of the number of thermoelectric elements of the top stage to the total number of thermoelectric elements is also optimized to maximize both the cooling load and the COP of the thermoelectric refrigerator. The effects of design factors on the performance are analyzed. (c) 2005 American Institute of Physics.