https://www.youtube.com/watch?v=KDRnEm-B3AI
"In this video we explore new methods of making cutting edge radiative sky
cooling paint with common grocery and hardware store items. This paint when
properly applied can allow for clean, electricity free air conditioning to
several degrees below ambient air temperature in direct sunlight."
Via Wayne Radinsky, who wrote:
Paint that gets cooler rather than hotter in direct sunlight.
That sounds like it violates the laws of physics, but actually, it doesn’t –
there’s a trick to it. The trick is to make a material that emits its
infrared radiation at a specific frequency that is not absorbed by the
atmosphere. The atmosphere is transparent to visible light which is why
sunlight comes straight down to us (at least on a clear day). But the
atmosphere isn’t transparent in the infrared. As such it traps a lot of
infrared radiation. But there are certain wavelengths where it is
transparent.
He doesn’t say what wavelength is ideal for this but he does say the best
material for this is barium sulfate. But the second best is calcium
carbonate, which is what you can get from hardware or grocery stores.
But just buying a boatload of calcium carbonate – or a material you can
transform into calcium carbonate with a simple chemical reaction – isn’t
enough. You need to make something called microspheres. So this video gets
deep into microsphere synthesis. He illustrates why you want microspheres of
certain sizes in order to maximizes packing density. You want the pigment
jam packed with particles when viewed in the microscope so there isn’t any
place where light can slip through.
Share and enjoy,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
