THE TRANSIENT BEHAVIOR OF PULSED SUPERCOOLING FOR THERMOELECTRIC COOLERS (TEC)

摘要

There exists the transient thermoelectric supercooling phenomenon that can be enhanced by keeping on increasing the Peltier effect to compensate for the Joule heating effect and Fourier heat conduction effect arriving at the cold junction, in which a transient cold spike can be produced by superimposing an additional shaped current pulse of a large magnitude above the original steady-state optimum value during the cool-down period. Most previous work of this transient thermoelectric effect focused on the minimum temperature achievable from a conventional thermoelectric module based on bismuth-telluride alloys. But the issues of the response time to reach a desired temperature, holding time of supercooling state and the recovery time back to the steady state were overlooked before. In this work, we systematically investigated the analytical solution by the condition of transient voltage pulse superimposed on the steady-state, for exploiting the coupling relationship among Peltier, Joule heating and Fourier heat conduction effects in the short time scale, and also discussing the advantage of certain pulse forms over others for TE device. The results indicated that, at a same room temperature, such pulsed operation of a TEC by the active control within the reasonable range, has enabled the cold junction to obtain an increased temperature drop that are significantly above the maximum cooling at the steady state, or cooling efficiency was increased dramatically under the smaller temperature differences between the hot and cold junctions. The discussions are geared towards enhancing the stability and reliability of pulsed TEC used as the precise temperature control device to satisfy the cooling level for high power packaging that are of current great interests.