Liquid crystal based active electrocaloric regenerator

Abstract

The active electrocaloric (EC) regenerator exploiting electric conversion into thermal energy has recently become important for developing a new generation of heat-management devices. We analyze an active EC regenerator numerically. We establish a temperature span across the regenerator $\Delta T$ by commuting a liquid crystalline (LC) unit between regions with and without an external electric field E. In modelling, we use Landau-de Gennes mesoscopic approach, focusing on the temperature regime where isotropic (paranematic) and nematic phase order compete. We determined conditions enabling a large enough value of $\Delta T$ suitable for potential applications. In particular, (i) the vicinity of the paranematic-nematic (P-N) phase transition, (ii) large enough latent heat of the transition, (iii) strong enough applied external field (exceeding the critical field E _c at which the P-N transition becomes gradual), and (iv) relatively short contact times between LC unit and heat sink and heat source reservoirs are advantageous. Our analysis reveals that $\Delta T\gg 1K$ could be achieved using appropriate LC material.

Keywords: Electro-caloric effect; Liquid crystals; Phase behavior.