Heat management and losses of electrocaloric cooling devices based on electrostatic thermal switches

Lucas Depreux (1) , Morgan Almanza (2) , Nouh Zeggai (2) , Fabien Parrain (1) , Martino Lobue (2)

1 C2N - Centre de Nanosciences et de Nanotechnologies
2 SATIE - Systèmes et Applications des Technologies de l'Information et de l'Energie

Electrocaloric cooling is a promising technology that could replace existing vapor-compression technology with lighter and more efficient solid state based devices. Among those, electrocaloric coolers using electrostatic actuation are rising; therefore harnessing their advantages and understanding their shortcomings is still a work in progress. In this paper, we pin down two limitations that stem from a commonly used device design, and we propose a model that takes them into account. The first is due to the displacement of the film, which moves the air around and causes losses. We estimate the air losses through a Poiseuille flow model. The second is related to the non-ideal Brayton cycle the device performs and which results in generating a heat flow opposite to cooling. We estimated the effect of this back-flow on the cold flux using a 2D thermal diffusion model. Ultimately, our results point at several possible improvements for further designs. Among them, a slight reduction of the air pressure in the device looks as a promising solution to reduce air losses.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Lucas Depreux, Morgan Almanza, Nouh Zeggai, Fabien Parrain, Martino Lobue. Heat management and losses of electrocaloric cooling devices based on electrostatic thermal switches. Applied Thermal Engineering, 2022, pp.118290. ⟨10.1016/j.applthermaleng.2022.118290⟩. ⟨hal-03616477⟩