Passive Chemical Heating

**pzona** · Nov19-09, 12:20 PM

Just out of curiosity, has anyone ever heard of using sodium thiosulfate pentahydrate (liquid crystals) as a viable method of heating a house? I'm doing a project on this now and it seems hugely inefficient due to the massive amounts of crystals that would be needed to produce enough energy to heat an entire house. The process is basically to take solid state crystals, melt them using solar power, and use the heat given off when the supercooled liquid crystals start to reform into a solid. I'm not asking for help with the project, I'm just wondering if this has been considered in detail before.

**Mech_Engineer** · Nov19-09, 12:31 PM

This chemical is used in chemical hand warmers, but I think you're right that you would need TONS of the stuff to heat a house for the winter.

http://en.wikipedia.org/wiki/Sodium_thiosulfate

**mgb_phys** · Nov19-09, 01:07 PM

There is a suggestion to do something like this with Southern Yellow Pine, it's resin melts at room temperature absorbing heat and saving you on AC and then freezes below room temp giving off heat.

The idea is to build log cabins with the stuff that are passively central heated.

**Borek** · Nov19-09, 01:57 PM

Check Glauber salt (sodium sulfate decahydrate) - as far as I know it is used in such systems.

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**pzona** · Nov19-09, 07:17 PM

I'm on week two of the experiment and so far the most heat generated is 4-5 degrees by about 40g of the crystals (although this is the temperature change recorded in a styrofoam calorimeter full of water; haven't gotten to the calculations yet). We made a scale model of a house, very small, about 0.2m by 0.2m, and 50g of the salt only heats it about 2 degrees C before cooling down. The main advantage I can see to this is that the cool down period is pretty gradual with good insulation.

mgb_phys, Has the Yellow Southern Pine resin idea been put into practice anywhere? This seems interesting, and may provide an alternative to present in my final report. Where can I find more information on its application?