Numerical analysis for transient supercooling effect of pulse current shapes on a two-stage thermoelectric cooler

Transient supercooling of TECs (Thermoelectric coolers) is a technology that can effectively strengthen cooling performance. It has been found that the pulse current shape has a significant impact on the enhancement of the transient supercooling. However, previous studies focused on a single-stage TEC or a two-stage TEC with the same square shape applied in the cold stage and hot stage. In this work, a new method is proposed to improve the transient supercooling performance by combining a two-stage TEC with pulse currents of various shapes (-t(-2),-t(1),-t(1/2),t(0),t(1/2)t(1),t(2)). A three-dimensional multi-physical field coupled transient model is used to verify the efficiency of the method. Pulse shapes, pulse amplitudes and pulse widths are analyzed in detail to reveal their effects on several important transient performance indexes of the two-stage TEC, including the minimum cold end temperature (T-c,T-min), the overshoot temperature (T-c,T-max), the holding time for supercooling state (t(hold)), and the time to recover to steady temperature (t(rec)). The results show that when the pulse current shape of one TEC stage is fixed, the T(c,min )will become lower if the other stage is given a falling pulse current with larger index or a rising pulse current with smaller index. Moreover, distinct optimal combined shapes are obtained when pursuing different high supercooling performance indexes. The combined pulse current t(0) + t(0) can be adopted to achieve a lower T-c,T-min, the combination of -t(1/2) + -t(1/2) can provide a lower T-c,T-max and a shorter t(rec) for the two-stage TEC, and the holding time t(hoid) can be prolonged by using the combination of t(2) + t(2).