DPRG List

 [DPRG] Solar still Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] Previous message: [DPRG] Solar still Next message: [DPRG] Solar still Subject: [DPRG] Solar still From: Randy M. Dumse rmd at newmicros.com Date: Mon Dec 23 16:23:01 CST 2002 ```Ed, You'll get about 100 watts per square meter on peak sunny days. With conversion inefficiencies, you'd be doing good if that turned into 70 watts of heating. So with a big dish, only a few hundred watts. To get the solar heating you're looking for, you'd need something like an acre of collectors. Think of it this way. Sun light is strong enough in the summer to heat your pool to 80 degrees. As the sun is lower in the sky in the winter, the light is less normal to the surface of the earth, so it contains less energy per square on the ground. What you're looking for is 1) to collect enough energy to make up that difference, 2) and collect enough more energy to make up for the heat loss to the cold stuff around the pool (that was 80 degrees or better, just like the pool, in the summer). So if the sun is 46 degrees lower in the sky (difference from Tropic of Cancer for summer to Tropic of Capricorn for winter) so you are only getting abou 72% of the incoming solar energy on your pool that you would in summer. So if you had a reflector that could put the heat from an area 40% larger than than your pool, you'd have the same amount of energy coming in. But! that's only the first half of the problem. The other half is everything around the pool is cooler, so you have to manage the heat loss (the energy flowing out from the poll by transfer to the colder bodies). I don't remember the formulas, except perhaps it goes by the second or third power or such. Meaning, a little difference in temperature... not much escape. A big difference in temperature (such as your pool and the surrounding ground in winter)... A HUGE AMOUNT of escape. You can poke around here http://scienceworld.wolfram.com/physics/topics/Heat.html if you want to look for a better description of the math of heat transfer. Randy > What I was > hoping to find were > formulas to help calculate how much heat I would get > if I were to make a 6 > foot, or larger still. ``` Previous message: [DPRG] Solar still Next message: [DPRG] Solar still Message index sorted by: [ date ] [ thread ] [ subject ] [ author ] More information about the DPRG mailing list