Sub-zero Celsius elastocaloric cooling via low-transition-temperature alloys.

Zhou, Guoan; Li, Zexi; Deng, Zhongzheng; Yao, Shuhuai; Safari, Ali; Zhang, Lingyun; Hua, Peng; Sun, Qingping · Nature · 2026

biomechanical · Level V

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Abstract

Elastocaloric cooling using shape-memory alloys (SMAs) is a promising greenhouse gas (GHG)-free alternative to conventional vapour-compression refrigeration that relies on high global warming potential (GWP) gas refrigerants<sup>1-4</sup>. However, existing elastocaloric systems have not yet reached sub-zero Celsius temperatures, which restricts their application in various freezing scenarios<sup>5,6</sup>. Here we constructed a compression-based, regenerative elastocaloric cooling device using low-transition-temperature tubular NiTi units in a cascaded configuration. The selected NiTi alloy exhibited superelasticity and substantial entropy changes down to -20 °C. Moreover, low-freezing-point aqueous calcium chloride solution was used as the heat-transfer fluid, ensuring effective flow at low operational temperatures. Our desktop device achieved a heat-source temperature of -12 °C from a room-temperature heat sink, paving the way for next-generation green elastocaloric freezing technologies.