Environment & Energy
Related: About this forumThinking about the idea of a DIY thermal solar collector.
Hi all,
I'm thinking about maybe building a thermal solar collector just for kicks and giggles.
There are a million sites out there about how to paint a 5 sided wood box black, throw some copper pipes in it, and place a piece of glass on top of it.
The collector obviously loses some of its heat to the environment though. Since a vacuum is a insulator, I'm wondering if it would be worthwhile or even feasible to attach a vacuum pump to the collector to increase the amount of heat it can extract.
I'm thinking I would have a six sided plexiglass box. I would paint polystyrene sheets black and lay them along the inside of five of those sides. Then I would lay a 50' copper coil inside of it. I would obviously need an input and output so that would probably be a solid piece of copper pipe fed through two holes in the plexiglass and sealed with silicone. I would also drill a third hole to attach the vacuum pump too. That tube would also have to be sealed with silicone. I'm thinking the vacuum pump could be a tire pump which I could hack so that it reverses the flow of air.
Thoughts?
pscot
(21,024 posts)eppur_se_muova
(36,246 posts)Something like polyurethane foam sandwiched between inner and outer box. You may even be able to pick up scraps of foil-clad foil panels from a construction site.
Plexiglas may not be the best choice. There's reasons glass is usually specified -- including the low softening point (as low as 85 C) of PMMA.
joshcryer
(62,265 posts)A light vacuum is quite feasible (there are videos about how to do it with piping), but overall foam is probably your best bet, and cheaper in the long run. You're at low thermodynamic temperatures so efficiency gains from such a vacuum system would be modest at best.