Numerical study on improving phase transition uniformity in elastocaloric regenerators

Abstract

Elastocaloric cooling is an emerging novel solid-state cooling technology with the potential to reduce carbon emissions in the refrigeration sector. In elastocaloric cooling systems, the core component is the active elastocaloric regenerator that exchanges heat between elastocaloric materials and heat transfer fluid. However, the temperature gradient within the active regenerator leads to inhomogeneous phase transitions along the flow direction, which could result in degradation of cooling performance or even fatigue of the material. To mitigate such a problem, in this study, four improvement strategies are proposed, namely segmented constrained strain, segmented variable strain profile, variable cross-sectional area, and variable transition temperature of the material. A one-dimensional simulation model based on energy equations is constructed to evaluate their improvement potential. In addition, considering practical constraints, the feasibility and generalization of each enhancement scheme are discussed. It was found that altering the cross-sectional area of the elastocaloric material can achieve a uniform phase transition with a 76.0% improvement in specific cooling power (SCP) and a 92.4% improvement in elastocaloric effect (eCE) within achievable processing precision.