A team of engineers from the University of Colorado has developed a solar heat sink plastic film to act as a kind of air conditioning system for structures. It has the ability to cool objects even in direct sunlight with zero energy and water consumption.

It does not consume energy and does not emit greenhouse gases. A new film, as thick as aluminum foil, could cool buildings and many other objects for years. This new material meets the challenge of cooling buildings that receive direct sunlight every day.

When applied to a surface, this new material cools the object by extracting its heat to emit it as infrared thermal radiation.

Yang and his team of engineers developed a film that reflects incoming sunlight and allows the blanket object to release heat in the form of infrared radiation. The process is called radiative cooling.

“This infrared light comes out through the so-called atmospheric window into outer space. Energy will keep coming out of the surface of the Earth and it will never come back. It’s probably the thinnest material you can imagine that will allow you to do this process, ”said Yin.

The new material, which is described in the journal Science, could provide an environmentally friendly means of cooling power plants, which currently require large amounts of water and electricity to maintain optimal operating temperatures for their machines.

This new material is only 50 microns thick – slightly thicker than kitchen foil – and can be inexpensively fabricated in rolls, making it a potentially viable technology on a large scale for residential applications and commercial.

“We generate a huge amount of heat that we waste,” said Ronggui Yang.

The material takes advantage of passive radiative cooling, the natural process by which objects emit heat in the form of infrared radiation, without consuming energy. The material can reflect solar energy, but in turn passes heat generated on the surface by infrared thermal radiation.

“Only 10-20 square meters of this material on the roof could cool a detached house in the summer” Tan Gang.

“You can apply this material on the windows,” Yang said. “Help freshen up a house.”

Besides being useful for cooling buildings and power plants, the material could also help improve the efficiency and life of solar panels. In direct sunlight, panels can overheat to temperatures that interfere with their ability to convert sunlight into electricity. It is only by applying this material to the surface of a solar panel that we can cool the panel and recover 1 to 2% solar efficiency. Which on a large scale is a considerable amount.

The film is much more energy efficient than air conditioners, which use electricity and refrigerants, both of which contribute to greenhouse gas emissions.

“We see great potential to bring it to market,” Yang said.

“For us, it’s just a wonderful thing,” Yin said. “We should try to get everyone to use it, if we can.”

“Think about if you apply a square meter film to each car,” Yin said. “This is already a great company that we are talking about.”

Engineers have applied for a patent for this new technology and are working to explore potential commercial applications.

The authors of the new research are Zhai Yao, Yaoguang Ma, Dongliang Zhao, Sabrina David, Runnan Lou, and HJ Smead.


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