Researchers at the Hong Kong University of Science and Technology (HKUST) have made a groundbreaking advancement by developing the world’s first elastocaloric freezer capable of operating at temperatures as low as -12°C. This innovative device represents a pivotal advancement in green refrigeration technology, aiming to transform the freezing industry while addressing climate change.
The findings, published in the esteemed journal Nature, detail a device that utilizes solid-state elastocaloric refrigeration technology. Unlike conventional freezing methods that rely on vapor compression cooling and harmful refrigerants, this new technology offers a zero-emission alternative. As global warming intensifies, the demand for effective freezing solutions continues to rise, contributing significantly to global energy consumption.
The research team, led by Prof. SUN Qingping, Chair Professor at the Department of Mechanical and Aerospace Engineering at HKUST, explored various materials and design structures to achieve this breakthrough. Their work highlights the potential for elastocaloric cooling to disrupt traditional refrigeration practices, which are responsible for approximately 27% of global Hydrofluorocarbon (HFC) emissions, equating to around 330 million tons of CO2 equivalent annually.
Innovative Design Features
The elastocaloric freezing device incorporates several advanced features. At its core is a super-elastic alloy made from a low-transition-temperature nickel-titanium (NiTi) alloy. This material maintains exceptional super-elasticity and a significant latent heat even at temperatures as low as -20°C. The device achieves a peak adiabatic temperature change of 16.3°C at 0°C, demonstrating its effectiveness in sub-zero conditions.
The technology further employs a freezing-resistant heat transfer fluid, specifically a 30wt% aqueous calcium chloride solution. This fluid remains fluid in sub-zero conditions and enhances heat exchange efficiency due to its favorable wettability on the NiTi surface. Additionally, the device features a cascaded tubular architecture that operates on a compression-based active Brayton cycle, consisting of eight cascaded units, each with three thin-walled NiTi tubes.
This innovative design allows the device to achieve a cold-source temperature of -12°C from a room-temperature heat sink of 24°C, establishing a temperature lift of 36°C. In practical tests, the device successfully cooled an insulated chamber to a stable -4°C within 60 minutes and froze 20 ml of distilled water into ice in just two hours.
Implications for Climate Action
The potential impact of this technology on climate change mitigation is substantial. As global regulations on HFCs become more stringent, the transition to zero-emission refrigeration solutions is critical. According to Prof. SUN, “This achievement demonstrates the potential for large-scale application of elastocaloric freezing technology. We are collaborating with industry to drive its commercialization.”
Prof. LU Mengqian, Director of the HKUST Otto Poon Center for Climate Resilience and Sustainability, emphasized the significance of this advancement in addressing the urgent need for sustainable freezing solutions. “This groundbreaking advancement in elastocaloric freezing technology represents a significant step forward in our fight against climate change,” Prof. LU stated.
The research was supported by the Strategic Topics Grant and General Research Fund of the Hong Kong Research Grants Council, as well as initiatives in collaboration with Shenzhen-Hong Kong. This milestone marks the second time the research team has published work in Nature within a year, following an earlier publication in February 2025 focusing on achieving kilowatt-scale elastocaloric cooling.
As the exploration of elastocaloric cooling continues, researchers at HKUST are committed to optimizing system efficiency and cost-effectiveness, which will be crucial for the successful implementation of this technology in the global freezing market.
