Achieving Better Super-cooling in a Two-Stage Transient Thermoelectric Device with Constraint-Free Pulse Current by Multi-Objective Optimization

As a promising energy conversion technology, transient thermoelectric device has potential applications in temperature control and refrigeration. The performance is sensitive to the applied current pulse. However, the conventional current pulse is limited to regular current shapes, which cannot achieve the best super-cooling performance. There exist strong coupling effects between the parameters of pulse shape, pulse amplitude, and pulse width. Simultaneous optimization of all the variables involved in a current pulse is a prerequisite to further improve the super-cooling. To bridge this gap, a constraint-free current pulse design concept was proposed in this study, which was successfully validated by a multi-objective optimization method. The results show that, the effective cooling regime and temperature overshoot both exhibit excellent features after optimization. Compared with the current t0 (mostly employed in previous studies), the betterments are improved by 88.33% and 92.13% for the effective cooling regime and the temperature overshoot, respectively. The underlying physics reveals that, the appropriate mediation between Peltier cooling, Joule heating, and Fourier conduction effects by a wave-like irregular current pulse is responsible for the improvement. The Pareto-optimal front found in the optimized current shape is beneficial for scientists and engineers to make an appropriate decision towards specific practical application.