Cheap, efficient, non-polluting A.C. ? Be still my beating heart...
The people who operated this ice house many centuries ago, would pour water in the pool as the sun set. And then something amazing happened. Even though the air temperature might be above freezing, say five degrees Celsius, the water would freeze. How did the water freeze if the air temperature is above freezing?
Our atmosphere doesn't absorb all of that heat. At certain wavelengths, in particular between eight and 13 microns, our atmosphere has what's known as a transmission window. This window allows some of the heat that goes up as infrared light to effectively escape, carrying away that pool's heat. And it can escape to a place that is much, much colder. The cold of this upper atmosphere and all the way out to outer space, which can be as cold as minus 270 degrees Celsius. So that pool of water is able to send out more heat to the sky than the sky sends back to it. And because of that, the pool will cool down below its surroundings' temperature. This is an effect known as night-sky cooling or radiative cooling.
I designed a multilayer optical material... It's more than 40 times thinner than a typical human hair. And it's able to do two things simultaneously. First, it sends its heat out precisely where our atmosphere lets that heat out the best. We targeted the window to space. The second thing it does is it avoids getting heated up by the sun. It's a very good mirror to sunlight. The first time I tested this was on a rooftop in Stanford that I'm showing you right here. I left the device out for a little while, and I walked up to it after a few minutes, and within seconds, I knew it was working. How? I touched it, and it felt cold.
The manufacturing method we used to actually make this material already exists at large volume scales. So I was really excited, because not only do we make something cool, but we might actually have the opportunity to do something real and make it useful.
Over the next year or two, I'm super excited to see this go to its first commercial-scale pilots in both the air conditioning and refrigeration space. In the future, we might be able to integrate these kinds of panels with higher efficiency building cooling systems to reduce their energy usage by two-thirds. And eventually, we might actually be able to build a cooling system that requires no electricity input at all. As a first step towards that, my colleagues at Stanford and I have shown that you could actually maintain something more than 42 degrees Celsius below the air temperature with better engineering.
https://www.ted.com/talks/aaswath_raman_how_we_can_turn_the_cold_of_outer_space_into_a_renewable_resource?rss#t-795098
Not got time to watch the video (so maybe it's covered there), but presumably this "radiate to space" could, at very large scale, counteract global warming too. No idea how large scale that would need, but...
ReplyDeleteI didn't watch the video either, I just read the transcript. I don't think there's anything there about that, just energy efficiency.
ReplyDeleteIt would help, I think. A/C costs a lot of electricity. If a roof were covered with this material, keeping it cooler, less A/C is needed to keep the occupants comfortable. This would be a wonderful tool for places like Arizona!
ReplyDeleteAdditionally, if you line covered parking with this, the cars would be cooler as well. It gets to 118°F in the summer here, so every bit helps!
Quicker and cheaper to simply bury one of your coils for geothermal heat exchange, but very few do it because it is far less expensive to use ambient air for your heat exchange. Getting space heat exchange sounds prohibitively expensive.
ReplyDeleteIt is a start for another evolution of cooling systems
ReplyDeleteThis is a truly good site post. Not too many people would actually, the way you just did. I am really impressed that there is so much information about this subject that have been uncovered and you’ve done your best, with so much class. If wanted to know more about green smoke reviews, than by all means come in and check our stuff. แอร์ ราคาถูก
ReplyDelete