Theoretical study on an integrated two-stage cascaded thermoelectric module operating with dual power sources

• An integrated two-stage thermoelectric module using dual power sources is studied.
• The cooling capacity and COP can reach their maximum at respective optimal currents.
• The maximum cooling capacity rises with increasing leg length allocation ratio.
• In the case of Qc,max, an optimum leg length allocation ratio can achieve an optimum COP.

This paper presents an integrated two-stage cascaded thermoelectric module (TTEM) operating with dual power source. The integrated TTEM contains two stages of thermocouples with identical semiconductor cross-sectional area but different leg lengths. An analytical model for the TTEM is developed, and the influences of the key parameters are theoretically investigated. The obtained results indicate that optimum two stage currents combination can maximize both the cooling capacity and coefficient of performance (COP). Furthermore, the leg length allocation ratio for the two stages affects the maximum cooling capacity significantly. Larger leg length proportion of the colder stage may effectively contribute to the improvement in maximum cooling capacity. In addition, there exists an optimum leg length allocation ratio to obtain the corresponding optimum COP when the two stage currents are set to achieve the maximum cooling capacity of the TTEM. However, the total leg length has no effect on the corresponding optimum COP.