Dynamic temperature response of electrocaloric multilayer capacitors

We measure and model the dynamic temperature response of electrocaloric (EC) multilayer capacitors (MLCs) which have been recently highlighted as novel solid-state refrigerators. The MLC temperature responses depend on the operation voltage waveform, thus we consider three types of voltage waveforms, which include square, triangular, and trapezoidal. Further, to implement an effective refrigeration cycle, the waveform frequency and duty cycle should be carefully chosen. First, our model is fitted to the measurements to evaluate an effective EC power and thermal properties, and calculates an effective cooling power for an EC MLC. The prediction shows that for a MLC with a thermal relaxation time for cooling, t_rc, a square voltage waveform with a duty cycle of 0 < d-≤ 0.3 and a period of t_rc < P-≤ 1.4t_rc provides the maximum cooling power. This work will help to improve the implementing methods for EC refrigeration cycles.