电卡制冷材料与系统发展现状与展望

Electrocaloric Cooling Materials and Systems:A Review and Perspective

电卡制冷循环基于巨电卡效应,利用电介质极化/退极化过程中的可逆焓变实现热力学循环。电卡制冷循环使用固态工质,环境友好、能量转化效率高。固态工质直接由电能驱动,结构简单,在微系统制冷领域拥有潜在技术优势。近十年来,国际上多个研究机构在铁电陶瓷、单晶、高分子、液晶等凝聚态材料中陆续观测到巨电卡效应;电卡制冷热力学循环研究亦均取得进展。本文从电卡效应的热力学原理、工质材料、制冷系统的仿真与验证三个方面综述电卡制冷技术的研究现状和发展方向。目前,电卡工质温变极限可达40~50 K,循环不可逆损失小于10%;理论热力学完善度可达40%~60%;实际系统零负载温宽达14 K。电卡制冷技术未来的发展需要在凝聚态相变理论、新材料合成、工质集成工艺、固态界面传热/传质、固态热力学循环等跨学科研究领域实现协同突破,从而发挥其在微制冷系统领域的技术潜力。在未来电卡制冷有望为我国芯片冷却、动力电池热管理等关键技术的发展提供高效、紧凑的热管理解决方案。

Electrocaloric cooling technology has advanced with the discovery of the giant electrocaloric effect,employing the entropy change during the poling and de-poling processes to enable operation of the refrigeration cycle.Electrocaloric refrigeration involves solid-state working bodies,without any greenhouse gas;thus,it is believed to be environmentally benign.The solid-state phase transition in the working bodies is directly induced by electricity,without any secondary energy transition,whereby a high energy efficiency and structural simplicity are achieved.These advantages enable provision of thermal management for micro-systems.After more than a decade of development,a large electrocaloric effect has been observed in many material systems such as ferroelectric ceramics,single crystals,polymers,and dielectric fluids.Several technical advances have been made in electrocaloric thermodynamic cycles and cooling device prototypes.This review article introduces the development status and the latest progress in electrocaloric refrigeration technology from three standpoints:the thermodynamic principle of the electrocaloric effect,the electrocaloric material,and the development and simulation of electrocaloric refrigeration devices.This article also discusses the opportunities and challenges faced in the field of electrocaloric refrigeration technology.The state-of-the-art electrocaloric refrigeration comprises an adiabatic temperature change of the material of 40-50 K,an irreversible loss of the working body of less than 10%,a theoretical thermodynamic perfection of 40%-60%,and a temperature span of the prototype of 14 K.Future advances in the field depend on the synergic development in the phase transition theory in condensed matter,the synthesis of new materials,material integration processes,a mass and heat transfer across the solid-state interfaces,and solid-state thermodynamic theory.Only when the above key development is achieved can one realize the possible advantages of electrocaloric refrigeration in micro-cooling systems,which may eventually provide solutions to aid on-chip cooling,battery thermal management,and many other technological aspects that require highly efficient,light-weighted,compact,and point-of-care thermal management.