Supercooling behaviours of thermoelectric coolers with different continuous Double-pulse current waveforms

This study innovatively identifies techniques to improve the transient supercooling performance of thermo-electric coolers (TECs) through continuous double-pulse currents with different waveforms. Some applications need to operate at a specific temperature while obtaining the requirement for long periods of refrigeration, thus the new effective cold-holding time (teff-hold) for the defined effective cooling line and the variation curve of the cold-end temperature was used as the main index to measure the transient performance of the TEC. In addition, the cold-end minimum temperature (Tc,min), overshoot temperature (Tc,max), and the time for recovery to steady-state temperature (trec) of TEC were considered comprehensively. A three-dimensional (3D) multi-physics coupling transient model was constructed using numerical simulations, and its accuracy was verified by experimental data. Five typical pulse waveforms (-t  2, -t1/2, t0, t1/2, and t2) were used as the research objects. The results demonstrated that the waveform of the continuous double-pulse current plays an important role in improving the teff-hold of TECs under transient working conditions. In this simulation, the pulse widths (r1 and r2) of the first and second pulse currents were both 4 s when the pulse initial current was the optimal current (0.6A). When the pulse amplitudes (P1 and P2) were equal and small, the pulse current combination of t0 + t1/2 was applied, which could achieve relatively large teff-hold values. However,-t2 + t1/2 was more appropriate. Addi-tionally, large teff-hold values for TECs could be achieved by reasonably choosing the pulse widths (r1 and r2) and amplitudes (P1 and P2) of continuous double-pulse waveforms and the initial current of the second pulse current (Iini,2). It is important to ensure that P1 is not too large, or it may lead to significant increases in Tc,min and Tc,max, a growth in trec, and a reduction in teff-hold. In this study, the optimal teff-hold was achieved (8.38 s) when the pulse current combination was-t2 + t1/2, P1 = 4, P2 = 3, r1 = r2 = 4 s, and Iini,2 = 0.55A.