Dark energy - passive nightime radiative cooling

mike95490

Anyone ever develop a homeowner scale product like this, for cooling a tank of water for a low energy "air conditioner" ?

useing a large radiator surface (open top tank or pan) exposed to un-clouded night sky, the combo of radiant heat from the water to the sky, and some evaporation, chills the water, so much that ancient desert dwellers could make ice at night


http://tinyurl.com/6mk3xq
Passive cooling of water at night in uninsulated open tank in hot arid areas
Ahmed Hamza H. AliCorresponding Author Contact Information, a, E-mail The Corresponding Author aDepartment of Mechanical Engineering, Faculty of Engineering, Assiut University, Assiut 71516, Egypt

http://www.jeffvail.net/2006/12/passive-cold.html
Passive Cold
Passive heating is pretty broadly understood. Passive cooling is less well known, though there are several different and viable methods. But most people think that "passive" and "ice" or "refrigeration" are just not possible. Not so. ....

http://www3.interscience.wiley.com/journal/114187370/abstract?CRETRY=1&SRETRY=0
Outgoing longwave radiation is the most practical way of cooling buildings in desert climates and is effective on roof surfaces, emitting the radiations from the surface of earth to the atmosphere and to outer space. Water evaporation in desert coolers is the usual method of cooling in arid regions. Nocturnal radiation both heats in winter and cools in summer, in suitable climates, and does so with no nonrenewable energy other than a negligible amount required to move the insulation twice a day.

http://www.treehugger.com/files/2007/04/eureka_the_sola.php
http://massmind.org/techref/other/spac.htm
http://www.ecosustainablevillage.com/solar_ice.htm
http://www.ornl.gov/sci/eere/international/Website/Nightsky%20Cools%20RoofTops.htm
http://www.yazakienergy.com/waterfired.htm
http://solaricemaker.com/

n3qik

Re: Dark energy - passive nightime radiative cooling

mike90045 wrote: »

http://tinyurl.com/6mk3xq <== Bad link

http://www3.interscience.wiley.com/journal/114187370/abstract?CRETRY=1&SRETRY=0<== Bad link

http://www.treehugger.com/files/2007/04/eureka_the_sola.php
http://massmind.org/techref/other/spac.htm
http://www.ecosustainablevillage.com/solar_ice.htm
http://www.ornl.gov/sci/eere/international/Website/Nightsky%20Cools%20RoofTops.htm
http://www.yazakienergy.com/waterfired.htm
http://solaricemaker.com/

reply to bad links.

mike95490

Re: Dark energy - passive nightime radiative cooling

re bad links.

Dang,
these things use fancy browser specific cookies. Usually tinyURL is pretty good. I'll have a go at this tomorrow.

Brock

Re: Dark energy - passive nightime radiative cooling

Basically that is how big cooling towers work, except they just pump the warm water in and blow huge fans at it. It works well in low humidity environments, when the water evaporates it uses a lot of energy and cools the water down pretty well.

The idea of somehow shading it during the day and opening iy up at night is a nice addition, but would require quite a bit of storage.

On the flip side of this...

Our house is cooled with a heat pump heating our pool or hot tub and cooling the house. This past summer (our fist in this house) we couldn't heat them up any more but still needed more cooling in the house. So I ran lines to the kids outside pool and warmed it up. At night I would leave it uncovered and put a small circulation pump in that made a "fountain" of sorts in the middle of it. It would cool off about twice as fast as just sitting uncovered. Same sort of principal at work cooling the water.