Scientists have
developed a thin, inexpensive material with extraordinary properties not found
in nature - to act as a kind of air conditioning system for structures with the
ability to cool objects even under direct sunlight with zero energy and water
consumption.
When applied to a surface, the
metamaterial film cools the object underneath by efficiently reflecting
incoming solar energy back into the space while simultaneously allowing the
surface to shed its own heat in the form of infrared thermal radiation.
The new
material could provide an eco-friendly means of supplementary cooling for
thermoelectric power plants, which currently require large amounts of water and
electricity to maintain the operating temperatures of their machinery.
The material
takes advantage of passive radiative cooling, the process by which objects
naturally shed heat in the form of infrared radiation, without consuming
energy. Thermal radiation provides natural night-time cooling and is used for
residential cooling in some areas, but daytime cooling has historically been
more of a challenge.
For a
structure exposed to sunlight, even a small amount of directly-absorbed solar
energy is enough to negate passive radiation. The challenge for the researchers
was to create a material that could provide a one-two punch: reflect any
incoming solar rays back into the atmosphere while still providing a means of
escape for infrared radiation.
To solve this, they embedded
visibly-scattering but infrared-radiant glass microspheres into a polymer film.
They then added a thin silver coating underneath in order to achieve maximum
spectral reflectance.
The research
was published in the journal Science.
Source: DNA-13th February,2017
