Enhanced Peltier cooling of two-stage thermoelectric cooler via pulse currents

As compared with single-stage thermoelectric coolers (TECs), two-stage TECs can achieve a larger temperature drop when TECs operate at steady state conditions. In this work, pulse currents are respectively supplied to the hot and the cold stage of a two-stage cascaded TEC to seek further increase in temperature drop across the TEC. The results show that the two-stage TEC yields a lower cold end temperature and a longer holding time of supercooling state than the single-stage counterpart. The minimum cold end temperature, Tc,min, can be further improved by the matching between the pulse amplitude and width on the cold stage (Pc and τc) and the pulse amplitude and width on the hot stage (Ph and τh). When Pc and τc are specified, the same Ph (=Pc) and a shorter τh (<τc) are required to yield a lower Tc,min. When the current pulse applied to the hot stage is triggered earlier than that to the cold stage, a lower cold end temperature and a longer holding time are observed. The results obtained in this work should be useful for both design and use of transient supercooling of TECs.