Researchers at the Hong Kong University of Science and Technology have unveiled the world’s first zero-degradation elastocaloric cooling device, a solid-state system maintaining a constant 400-watt cooling power and a 41-kelvin temperature span over one million operational cycles, according to a university press release.
Overcoming Shape Memory Alloy Functional Fatigue
Traditional vapor-compression refrigeration relies heavily on energy-intensive systems and refrigerants that exacerbate the greenhouse effect and damage the ozone layer. Elastocaloric cooling offers a green alternative by utilizing the reversible stress-induced phase transformation of shape memory alloys. However, commercial adoption has stalled due to performance degradation and low reliability. According to researchers, the prevalent use of commercial NiTi shape memory alloy as a refrigerant causes functional fatigue, leading to a decline in cooling power over extended use.
To eliminate this bottleneck, a research team led by Prof. SUN Qingping, Chair Professor in the Department of Mechanical and Aerospace Engineering at HKUST, developed a new quaternary TiNiCuCo alloy. Unlike traditional NiTi materials, this fatigue-resistant alloy provides stable elastocaloric performance through numerous cyclic phase transitions. Its consistent release and absorption of latent heat serve as a dependable solid-state refrigerant.
Double-Layer Fin Refrigerant Structure and Device Architecture
Beyond material chemistry, the HKUST team redesigned the physical refrigerant structure to improve mechanical reliability. They fabricated a double-layer fin-type refrigerant structure designed to enhance heat transfer efficiency and buckling resistance. This configuration achieves an ultra-high fatigue life exceeding 10 million cyclic compressive cycles, according to university documentation.
The device architecture was also optimized to reduce thermal losses and improve overall system stability. The engineering refinements achieved a 50 percent reduction in components and lowered the proportion of ineffective parts from 15 percent to 5 percent. Integrated with multiple refrigerant units, the system delivered a constant cooling power of 400 watts and sustained a 41-degree Celsius temperature difference over one million cycles without degradation.
Did You Know? Accelerated fatigue testing of the TiNiCuCo refrigerant showed zero functional degradation after 100 million cycles, positioning the solid-state material to operate reliably for more than a decade under real-world conditions, according to HKUST data.
Pathways to Sustainable Air Conditioning and Market Commercialization
This development follows earlier advancements by HKUST researchers, including a kilowatt-scale system developed in 2025 that achieved 1,284 watts of cooling power. While that earlier system demonstrated the raw potential of elastocaloric technology for air-conditioning applications, the latest breakthrough solves a separate challenge: long-term durability and operational consistency.
"We are currently developing an air-conditioner based on this technology. Moving forward, we aim to further enhance energy efficiency, power density, and cost competitiveness of elastocaloric refrigeration systems to accelerate their market adoption as a sustainable cooling solution." The findings were published in the academic journal Joule under the title "A zero-degradation elastocaloric cooling device using fatigue-resistant refrigerant."
Frequently Asked Questions
What makes elastocaloric cooling greener than traditional refrigeration?
Traditional vapor-compression systems use energy-intensive refrigerants that harm the ozone layer and contribute to global warming. Elastocaloric cooling uses solid-state shape memory alloys undergoing reversible stress-induced phase transformations, eliminating harmful chemical refrigerants.
How long will the new HKUST cooling refrigerant last in real-world use?
Accelerated fatigue testing of the TiNiCuCo refrigerant showed no functional degradation after 100 million cycles, with real-world operating projections exceeding a decade, according to HKUST.
What is the cooling capacity of the new device?
The newly constructed device achieves a constant cooling power of 400 watts and maintains a temperature span of 41 degrees Celsius over one million operation cycles.
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