New breakthrough in zero energy technology keeps things cool, without the need for electricity

Imagine a system that can provide cooling for building air conditioning, food refrigeration and many other applications… all without electricity.

This may sound like science fiction, but thanks to the efforts of researchers at MIT, an innovative new passive cooling system could one day replace several conventional technologies, offering an alternative that requires no power input and instead only requires a moderate amount of water to run. function.

By combining principles involving three separate approaches to cooling (radiative, evaporative, and thermal insulation cooling), the team has developed a new technology that they say offers cooling up to 19 degrees Fahrenheit from ambient temperature. The system, which resembles existing solar panels, could enable safe food storage in most conditions, and even triple shelf life in extremely dry conditions.

Although each of the three cooling methods employed in recent MIT research has proven successful on its own, it was the team’s unique approach to combining them that produced the new zero-energy passive technology.

“This technology combines some of the good features of previous technologies, such as evaporative cooling and radiation cooling,” says MIT postdoc Zhengmao Lu, whose team published their findings in Cell Reports Physical Sciences. According to Lu, the combined technologies enabled significant extensions of food preservation, even in high humidity conditions that normally shorten the period in which they can be safely consumed.

Zhengmao Lu, a postdoctoral associate in the MIT Department of Materials Science and Engineering, was the lead author of the study (Credit: MIT/Zhengmao Lu).

In addition to its use as a stand-alone, zero-energy technology for cooling systems, Lu believes the new technology developed by him and his MIT colleagues could also complement existing cooling systems by reducing the amount of energy needed to run them. One of the most obvious applications would involve reducing the amount of electricity needed to power air conditioning systems in hotter climates.

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“By lowering the temperature of the condenser, it can effectively increase the efficiency of the air conditioner,” Lu said recently in a statement, adding that such combinations of existing and newer technologies could “potentially save energy.” The same would apply in humid regions, Lu says, where even the best radiative cooling technologies often struggle to maintain optimal performance.

The MIT team’s design was based on building material in three layers that cool water and heat passing through them. The top layer is an airgel, which is a spongy material made of polyethylene filled with tiny air-filled bubbles or cavities. One of the unique benefits of aerogels is that they allow water vapor to pass through, while still acting as excellent insulators. They also allow the passage of infrared radiation, which is vital in allowing upward release of heat into the air, unlike the way radiative air conditioning systems release hot air as a result of the power required to operate them.

zero energy technology
Above: Diagram showing the cooling system designed by the MIT team (Credit: Zhengmao Lu, et al, Cell Reports Physical Science).

The second layer, a hydrogel, is similar to the airgel layer above it, although its cavities are filled with water that facilitates the evaporation needed for cooling. Lastly, a third layer with a reflective surface helps prevent sunlight that may pass through the first two layers from being absorbed, reflecting it back onto the airgel and hydrogel layers above.

Although no energy would be required, water in moderate amounts, perhaps as little as twice a week, would be required for evaporation to occur in particularly dry regions. Wetter areas may require even less maintenance, and in most cases water is only added once a month.

According to Lu, bringing the three cooling approaches together into a single innovative passive cooling system was recognized by Ream as a truly novel approach. Even in early phases of testing involving small versions of the new technology combined in a rooftop area at MIT, the team managed to demonstrate capabilities amounting to nearly 19 degrees of cooling.

The team believes this new technology could one day help supply cooling systems in many parts of the world where electricity, water and other resources are in extremely short supply.

The team’s study, titled “Significantly Enhanced Passive Subenvironmental Cooling Enabled by Evaporation, Radiation, and Insulation,” was recently published in Cell Reports Physical Sciences and can be read online.

Micah Hanks is the editor-in-chief and co-founder of The Debrief. Follow his work at micahhanks.com and on Twitter: @MicahHanks.

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