Experimental study on transient supercooling of two-stage thermoelectric cooler

In this work, an experimental study was conducted to evaluate the cooling performance of two-stage thermoelectric coolers (TECs) under current pulse operation so as to achieve a larger temperature drop. Measured data disclosed that the steady electric current varied from 0.1 to 4.1 A and the optimal current was found to be I-opt= 2 A. The implementation of transient supercooling was found to reduce the minimum temperature from 236.65 to 232.90 K, corresponding the temperature drop of 3.75 K. The results further indicated that the increment of pulse current leads to the reduction of the T-c,T-min. However, for tau = 5 s, further increment of the pulse current from 4 A to 4.5 A did not lead to the lower T-c,T-min, which can be attributed to the large magnitude of the current so that the heat sink cannot remove much heat and it would be fed back to the cold side. Thus, the least T-c,T-min was achieved for 4 A. Regarding the variation of pulse width, it was obtained that T-c,T-min is decreased tending to a particular value. Accordingly, the least T-c,T-min of 232.8 K was attained by applying a pulse current with tau = 6 s.