New Heat Transfer Technology
A new ultra thin multi layered material can bring cooling to buildings without air conditioning by radiating heat from inside the buildings away into the space and reflecting sunlight to minimize incoming heat.
Stanford Researchers, including one of the Indian origins have successfully developed a revolutionary ultra thin coating material that keeps building cool by radiating heat away from them and then sending it directly into space. This ultra thin multi layered material deals with light in both visible as well as invisible way and is developed by a team led by electric engineering Professor Shanhui Fan and research associate Aaswath Raman.
The material is just 1.8 µ thick which is thinner than the thinnest aluminum foil. In addition to the new material dealing with infrared light, is also a devastating decisive efficient mirror that reflects virtually all of the incoming sunlight that hits it.
The Stanford team called this effective result as “photonic radiative cooling”. It is a one-two punch that dis burdens infrared heat from within a building while reflecting the sunlight that would otherwise warm it up. The result is cooler buildings that require low air conditioning.
This material paves the way for cooler buildings that require less air conditioning. The coating radiates heat-bearing infrared light directly into space. It transmits this infrared light away from buildings at the decisive frequency that allows it to evade through the atmosphere without heating the air.
This multi layered coating also acts as a highly efficient mirror, diminishing 97% of sunlight from hitting the building and heating it up. Together, the radiation as well as reflection make the photonic radiative by approx 9° Fahrenheit cooler than the surrounding air during the day
It is made of seven layers of silicon dioxide with hafnium oxide laying on top of a thin layer of silver. These layers are not having invariable thickness, but are instead engineered to design a new and unique material. Its internal structure is tuned to emanate infrared rays at a frequency allowing them to evacuate into space without warming the air near the building.
According to Linxiao Zhu, doctoral candidate in applied physics and a co-author of the paper “This photonic approach gives the ability to finely tune both solar reflection and infrared thermal radiation”.