MIT researchers advance cooling technology that does not use electricity

Roadblock to commercialization

The technology can also be used to lower the load that air conditioning compressors go through by cooling them. This would increase the air conditioner efficiency and lead to energy savings too. However, there is a major roadblock before this technology can be scaled up commercially.

Previous attempts at using passive cooling have gained partial success since the evaporative materials used in the process would heat up under the Sun and be unable to provide sufficient cooling. The airgel used in these experiments was developed by the MIT team and involves an expensive manufacturing process.

Solvents used in the manufacture of the airgel need to be removed slowly without damaging the airgel structure. This is achieved with specialized equipment that facilitates critical point drying (CPD), which increases the cost.

The researchers are now working to determine if inexpensive methods such as freeze drying or the use of alternative materials could avoid the need for CPD, thereby reducing costs. As of now, the team doesn’t know when exactly this would be possible.

Findings of the research conducted can be found in the journal Cell Reports Physical Science.

Abstract:

Passive cooling relying on evaporation and radiation, while offering great energy-saving opportunities, faces challenges with low ambient cooling powers, environmental heating, high water usage, and climate condition constraints. To overcome these shortcomings, here, we present insulated cooling with evaporation and radiation (ICER), which utilizes a solar-reflecting layer; an infrared-emitting evaporative layer; and an infrared-transparent, solar-reflecting, and vapor-permeable insulation layer. One major advantage of ICER is that it synergistically combines thermal insulation, evaporative cooling, and radiative cooling. Consequently, it consistently achieves below-wet-bulb temperatures with much less water consumption than pure evaporation while reaching 9.3°C below the ambient temperature under direct sunlight. With unfavorable climate conditions, ICER delivers 96 W/m2 daytime cooling power at the ambient temperature and shows a 300% enhancement over the state-of-the-art radiative cooler. During the summer months, without electricity, ICER can extend food shelf life by 40% in humid climates and 200% in dry climates with low water-refilling frequencies.

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