Evaluating optimal cooling temperature of a single-stage thermoelectric cooler using thermodynamic second law

This paper presents a theoretical analysis based on the second law of thermodynamics to evaluate the optimal performances of a single-stage thermoelectric cooling system. The cold exergy and exergy efficiency are chosen as the optimization objectives, and a new entropy generation number associated with entropy generation, cold exergy and cooling temperature is proposed. The influences of several key parameters such as electric current, thermal conductance allocation ratio and cooling temperature on the cooling performance are theoretically investigated. The results indicate that the criterion of entropy generation number could be used as a new dimensionless measure of TEC system irreversibility. Furthermore, the cooling temperature can be considered as an important variable for TEC system to be optimized. It is found that an optimal cooling temperature exists, leading to the maximum cooling capacity and exergy efficiency, respectively. Thus, the cooling temperature should be considered in the design and application for practical TEC systems in order to obtain the maximum performance benefit. The present study can provide guidelines for the design and application of practical thermoelectric cooling systems.