U.S.A.. Stanford University is currently testing an innovative cooling technology that uses radiative cooling from the sky. The radiative cooling of the sky is a mechanism that allows cooling to temperatures below the environment without electricity or water evaporation.
In this approach, heat is passively rejected in outer space by exploiting the fact that the Earth's atmosphere is partially transparent to the thermal infrared radiation.
In an 2014 study, the Stanford researchers showed the cooling capabilities of a mirror-like optical surface they were testing on the roof of the Packard Building at Stanford. Other research published in September by 2017 showed that a system that involves these surfaces can cool the water that flows at a lower temperature than the surrounding air.
In fact, in the system tested by the researchers, the panels covered in the specialized optical surfaces could consistently reduce the water temperature from 3 to 5 ° C below the ambient temperature during a period of 3 days. In a simulation where their panels covered the roof of a commercial office in the hot weather of Las Vegas, the scientists calculated that the panel-cooled system would save 14.3 MWh of electricity, which represents a reduction of 21% in the electricity used to cool building.
"This research is based on our previous work with radiative cooling from the sky, but it takes it to the next level." For the first time, it provides a demonstration of high fidelity technology of how radiative cooling of the sky can be used to passively cool a fluid and, in doing so, connect it to cooling systems to save electricity, "said Aaswath Raman, who is a senior co-author of the paper detailing this research, published in Nature Energy's September 4.
The radiative cooling of the sky is a natural process that everyone and everything does, as a result of the moments when the molecules release heat. It can be witnessed in the heat that comes out of a road, since it cools down after sunset. This phenomenon is particularly noticeable on a cloudless night because, without clouds, the heat that we radiate and everything around us can more easily reach through the Earth's atmosphere, to the vast and cold confines of space.
At this time, researchers are measuring the energy saved when the panels are integrated with traditional air conditioning and refrigeration systems in a test facility; Fan, Goldstein and Raman are optimistic that this technology will find wide application in the years to come. Researchers focus on making their panels easily integrated with standard air conditioning and refrigeration systems and are particularly excited about the prospect of applying their technology to the serious task of cooling data centers.