Researchers in China say they have now developed a cooling device that, by absorbing heat, brings down skin temperature by 7°C. By cooling peopleinstead of entire buildings, it could cut the energy use of standard air-conditioning in half, the team reports in the journal Cell Reports Physical Science.

“Our design aims to solve several critical problems of traditional air-conditioning systems,” says Yuekuan Zhou, a sustainable energy and environment researcher at The Hong Kong University of Science and Technology. “Its low energy efficiency in large open spaces, the spread of pollutants and airborne disease transmission through air-conditioning systems, and the discomfort caused by fan noise and airflow.”

Zhou and colleagues designed a novel cooling device built on a commercial thermoelectric heat pump. Thermoelectric coolers transfer heat from one side of the material to another, and are used in high-end portable coolers and mattress pads.

On one side of the thermoelectric module, the researchers connected four pipes and a small fan that act like a heat sink; the fan only moves air over the device. On the other side, they attached an aluminum panel that acts as an extremely cold surface that absorbs heat radiation.

As a proof of principle, the researchers made a 10 cm x 10 cm device and placed it in front of a human skin simulator. The device brought down the artificial skin temperature by 7.3°C across varying room sizes and air change rates.

The device can operate with windows open, which helps to reduce the transmission of airborne diseases, Zhou says. The noise level and airflow in front of the device were also low at 40 dBA and 0.5 m/s respectively, significantly improving thermal comfort.

Others have made heat-absorbing panels for outdoor personal cooling before. This new device is intended to be portable and used inside. “This helps to ensure that the device can always be close to people so that it can work with high efficiency and effectiveness,” he says.

Zhou adds that the technology should be viable on a large scale. The commercial thermoelectric cooling (TEC) modules they use in the device are available at remarkably low prices. And the other materials they use are also simple and inexpensive. The team is now developing a large-scale radiant cooling device to validate its feasibility.

Source: Xinyao Zheng et al. A pure radiant cooling device for ‘‘air conditioning’’ without conditioning air. Cell Reports Physical Science, 2024.