Insight into electrocaloric cooling power in multilayer capacitors using infra-red camera

International audienceCompact multilayer capacitors (MLCs) have attracted strong interest as the most promising elements for the design of electrocaloric prototypes. Recent theoretical simulations have predicted that MLCs could permit a sustained cooling power. However, direct experimental evidence is still lacking. Here, we use an infra-red camera to characterize the cooling power of commercial MLCs by combining both spatially and temporally resolved measurements. We also compare the experimental data with theoretical models in order to highlight the routes for developing and optimizing the future MLC-based devices as well as the measurement conditions and modeling tools

Large heat flux in electrocaloric multilayer capacitors

International audienceMulti layer capacitors (MLCs) are considered the most promising refrigerant elements for the design and development of electrocaloric cooling devices. Recently, the heat transfer of these MLCs has been considered. However, the heat exchange with the surrounding environment has been poorly addressed. In this work, we measure by infrared thermography the temperature change versus time in four different heat exchange configurations. Depending on the configurations, Newtonian and non-Newtonian regimes with their corresponding Biot number are determined, providing useful thermal characteristics. Indeed, in the case of large area thermal pad contacts, heat transfer coefficients up to 3400 W centerdot m−2 centerdot K−1 were obtained, showing that the standard (non-optimised) MLCs already reach the needs for designing efficient prototypes. We also determined the ideal Brayton cooling power in case of thick wires contact that varied between 3.4 mW and 9.8 mW for operating frequencies varying from 0.25 Hz to 1 Hz. While only heat conduction was considered here, our work provides some design rules for improving heat exchanges in future devices