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05-04-2011, 01:20 AM #1Regular Guest
- Join Date
- Jun 2004
Solar storage above 100 C / 212 F?
Is there any method available to homeowners to store thermal energy above 212 F?
I see evacuated glass / heatpipe solar collectors can be extremely efficient at capturing solar energy, but typically they are used solely for water heating, and you kinda get this boiling problem around 212 degrees that reduces efficiency.
Is there some inexpensive way to allow for higher thermal storage temperatures that does not use water as the thermal transfer agent?
I see salt is rather high, with a melting point of 801 C / 1474 F. Are there any other moderately safe substances for high-temperature homeowner use?
06-07-2011, 10:13 PM #2Professional Member
- Join Date
- Jun 2011
- Virginia Beach VA
Water only boils at 212F if it is at atmospheric pressure, ~15 psi. If you keep water in a pressure tank it is possible to keep water liquid well above 212. For example at 228F the pressure goes up only 5 lbs above atmospheric. A 30 psi tank would hold water up to 250F. If that's not hot enough you can get an ASME pressure tank to handle these or higher temperatures/pressures, see this chart. But really, you could just get a thermal oil which would be OK up to 600F like therminol xp. The question is why do you need to do this?