A team of researchers from the Hong Kong University of Science and Technology (HKUST) has created the world’s first kilowatt-scale elastocaloric cooling device, a new type of air conditioning system that is energy-efficient and environmentally friendly.
This breakthrough technology can cool indoor spaces quickly, reaching a comfortable 21°C–22°C within just 15 minutes, even when outdoor temperatures are above 30°C.
The research, published in the journal Nature, offers a promising solution for reducing energy consumption and cutting down greenhouse gas emissions in the cooling industry.
Why do we need a new cooling technology?
As global temperatures rise, the need for air conditioning is increasing. Currently, cooling systems use about 20% of the world’s electricity and rely on refrigerants that contribute to climate change.
The new elastocaloric cooling technology provides an eco-friendly alternative. Instead of using harmful gases, this system relies on special materials called shape memory alloys (SMAs), which release or absorb heat when they are compressed or stretched.
Although elastocaloric cooling has been studied for years, previous designs could only produce a maximum cooling power of about 260 watts, far below the level needed for commercial air conditioning.
The HKUST research team, led by Prof. Sun Qingping and Prof. Yao Shuhuai, identified two major problems preventing the technology from scaling up:
- Balancing Cooling Power and Material Efficiency – It was difficult to get enough cooling power while keeping the system lightweight.
- Improving Heat Transfer Efficiency – The process of removing heat was too slow for high-performance cooling.
To overcome these challenges, the researchers designed a new system called the “SMAs in series—fluid in parallel” multi-cell architecture. This system includes 10 cooling units, each made up of four thin-walled nickel-titanium tubes, arranged in a way that significantly boosts cooling performance.
- The nickel-titanium tubes have a high surface area, which improves heat transfer.
- A parallel fluid channel keeps system pressure low, ensuring smooth operation.
- Instead of using regular distilled water, the researchers added graphene nanofluid, which improves heat transfer by 50%.
Tests showed that the device can produce a total cooling power of 1,284 watts, making it the first elastocaloric cooling system to reach the kilowatt scale.
The cooling system was tested in a 2.7 cubic meter model house in outdoor temperatures of 30°C–31°C. Within just 15 minutes, the system lowered the indoor temperature to a comfortable 21°C–22°C.
A game-changer for the air conditioning industry
Compared to previous solid-state cooling technologies, this new device leads the way in cooling power and efficiency.
- It has a specific cooling power (SCP) of 12.3 W/g, almost three times better than previous liquid-based elastocaloric cooling devices.
- It is zero-emission, meaning it does not release harmful greenhouse gases.
- It is energy-efficient, which could lower electricity bills for consumers.
- It can be more compact, freeing up indoor space.
Prof. Sun Qingping says that this technology could soon be used in commercial air conditioners. As governments worldwide impose stricter rules on hydrofluorocarbon (HFC) refrigerants, this green cooling system could become a key solution for carbon neutrality.
Prof. Yao Shuhuai adds that future improvements could make the system even more powerful and efficient by using new materials and optimizing the mechanical design.
This breakthrough builds on the team’s previous success in 2024, when they developed an elastocaloric cooling device capable of a 75 K temperature lift, published in Nature Energy.
With continued advancements, this technology could revolutionize the cooling industry—offering a greener, more efficient alternative to traditional air conditioning.
