Researchers unveil highly efficient, low-emission cooling tech with 67 joules of heat absorption per gram

Cooling/refrigeration technology is one of the most critical inventions of man, but comes with a steep environmental cost. Widely used vapor-compression cooling systems account for nearly 15% (2019 data) of electricity consumption in China and over 7.8% (2020 data) of global carbon emissions. While solid-state caloric materials have emerged as a low-emission alternative, their inability to efficiently transfer heat has severely limited large-scale implementation.

Now, a research team led by Prof. Li Bing at the Institute of Metal Research, Chinese Academy of Sciences, has cracked this "impossible triangle" of high cooling capacity, efficient heat transfer, and zero-carbon emissions. Publishing their findings in journal Nature, the scientists introduced a novel method based on the dissolution barocaloric effect.

The team achieved this by using an ammonium thiocyanate (NH₄SCN) salt solution. The process combines the thermal benefits of solid coolants with the rapid flow capabilities of liquids. By turning the coolant into a pumpable fluid, the system responds instantly to pressure changes without the heat-transfer bottlenecks that plague traditional solid boundaries.

The core mechanics of this new cooling cycle operate in a simple sequence:

• Pressurization: applying pressure causes the solid salt to prececipitate out of the solution, which releases a lot of heat.
• Depressurization: removing the pressure causes the salt to rapidly dissolve back into the water, absorbing a masssive amount of heat and drastically dropping the temperature.

During experiments at room temperature, the fluid's temperature plummeted by nearly 30 kelvins (almost 30°C) in just 20 seconds. The cooling span reached as high as 54 kelvins at elevated temperatures. Simulations of a prototype four-step cycle showed an energy efficiency approaching 77% and a cooling capacity of 67 joules per gram.

With global cooling demand projected to triple by 2050 (2022 data), this stable and reversible technology paves the way for commercial, zero-emission refrigeration. Its exceptional high-temperature performance makes it particularly suited for managing the intense thermal loads of next-generation artificial intelligence computing centers.