World’s first kilowatt-scale elastocaloric green cooling device developed

Researchers on the Hong Kong College of Science and Expertise (HKUST) have developed the world’s first kilowatt-scale elastocaloric cooling machine. The machine can stabilize indoor temperatures at a cushty 21°C–22°C in simply quarter-hour, even when outside temperatures attain between 30°C and 31°C, marking a big breakthrough towards the industrial software of elastocaloric solid-state cooling expertise.

The analysis findings have been published within the journal Natureproviding a promising resolution to fight local weather change and speed up the low-carbon transformation of the worldwide cooling business.

As world warming intensifies, the demand for air conditioning and cooling has been rising, with cooling already accounting for 20% of world electrical energy consumption. Mainstream vapor compression cooling expertise depends on refrigerants with excessive world warming potential (GWP).

As an eco-friendly various, solid-state cooling expertise based mostly on the elastocaloric impact of form reminiscence alloys (SMAs) has drawn substantial focus from each academia and business attributable to its zero greenhouse fuel emissions and excessive vitality effectivity potential.

Nonetheless, the utmost cooling energy of earlier elastocaloric cooling gadgets was round 260 watts, which couldn’t meet the kilowatt-scale requirement for industrial air-con. The HKUST analysis group, led by Prof. Solar Qingping and Prof. Yao Shuhuai, each professors from the Division of Mechanical and Aerospace Engineering (MAE), recognized that this bottleneck stems from two core points: (1) the problem in balancing the particular cooling energy (SCP) of the refrigerant with the entire energetic mass; and (2) inadequate warmth switch effectivity throughout high-frequency operation.

To beat these limitations, the analysis group proposed an “SMAs in series—fluid in parallel” multi-cell structure design. This structure serially connects 10 elastocaloric cooling models alongside the course of drive software, with every unit containing 4 thin-walled nickel-titanium alloy tubes, totaling a mass of solely 104.4 grams.

The nickel-titanium tubes characteristic a excessive floor area-to-volume ratio of seven.51 mm^-1 that considerably improves warmth alternate effectivity. In the meantime, the parallel fluid channel design retains system strain under 1.5 bar, guaranteeing steady high-frequency operation.

One other key innovation is changing conventional distilled water with graphene nanofluid, a cutting-edge warmth switch medium with distinctive thermal conductivity. Experiments confirmed that graphene nanofluid, at simply 2 grams per liter focus, conducts warmth 50% extra effectively than distilled water.

The diameter of its nanoparticles (0.8 micrometers) is far smaller than the width of the fluid channels (150–500 micrometers), avoiding blockage dangers. X-ray tomography confirmed that the nickel-titanium tubes maintained uniform compressive deformation below a stress of 950 megapascals with out buckling failure.

At a excessive frequency of three.5 Hz, the machine achieved a selected cooling energy of 12.3 W/g and a complete cooling energy of 1,284 watts (below zero temperature raise circumstances), demonstrating its sensible viability in real-world circumstances.

In sensible software checks, the machine efficiently cooled a 2.7 m³ mannequin home in a summer time outside atmosphere with temperatures between 30℃ and 31℃, stabilizing the indoor temperature at a cushty 21℃–22 ℃ in quarter-hour.

In contrast with present solid-state cooling applied sciences, this pioneering machine leads when it comes to cooling energy and temperature raise efficiency. Its SCP worth (12.3 W/g) almost triples the earlier file of liquid warmth switch elastocaloric gadgets (4.4 W/g), and it has for the primary time damaged by way of the kilowatt-scale cooling threshold.

Prof. Solar Qingping stated, “This achievement demonstrates the potential for the large-scale software of elastocaloric cooling expertise. We’re working with the business to drive its commercialization.

“As global regulations on hydrofluorocarbons (HFCs) tighten, this zero-emission, energy-efficient cooling technology is poised to reshape the air conditioning industry and provide a key technical solution for carbon neutrality. Consumers will also benefit from lower energy bills while the technological advancements enable more compact cooling devices that save valuable indoor space.”

Prof. Yao Shuhuai stated, “In the future, the system’s cooling performance can be further improved by developing new elastocaloric materials and optimizing the rotary drive architecture. These improvements can help achieve larger cooling powers, meaning indoor environments can be cooled down in significantly less time.”

This innovation has come as one other main breakthrough by the analysis group in lower than a yr. It builds on their earlier success with a multi-material elastocaloric machine that units a file of 75 Okay temperature life, as printed in Nature Vitality in 2024.