Skycool Systems is a Stanford spin-out that uses panels composed of "layers of silicon dioxide and hafnium oxide on top of a thin layer of silver" to convert the waste-heat from air-conditioners' heat exchangers into 8-13 micrometer radiation, which passes through the atmosphere and radiates into space.
The company's models predict that using the panels over 60 percent of a two-story Vegas building's roof would improve air-conditioning efficiency by 21 percent.
As a practical application for the system, the researchers built a model in which the radiative water-cooling panels cool the condenser coils of a building's air-conditioning system, providing an assist to the system's cooling fans. The circulating fluid helps siphon more heat from the condenser, increasing efficiency. Water that's cooled by only a few degrees can make a big difference: In general, the electricity needed for a cooling system is reduced by 3 to 5 percent for every degree Celcius the condenser temperature drops.The model showed that cooling a two-story commercial office building in Las Vegas with fluid-cooling panels—which covered 60 percent of the roof—cut the building's electricity use by 21 percent compared with using only a traditional fan-based condenser during the hot summer months of May through August.
New radiant cooling systems, which use chilled water running through aluminum panels or pipes, are getting more common in Europe and China and in high-efficiency buildings in the U.S., says Raman. "If we could couple our system with such radiant cooling systems, we could get 70 percent efficiency savings."
Efficient Air-Conditioning Beams Heat Into Space
[Prachi Patel/IEEE Spectrum]
(via Dan Hon)
(Image: Aaswath Raman)
