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Using Sodium Ethanoate (Sodium Acetate), And Evacuated Solar Thermal Collector Tubes To Create A Cloudy Day Backup Heat Storage Medium For A Solar Domestic Hot Water Or Solar Hydronic Space Heating System


Years ago, there were on the market some re-usable hand-warmers, that could be recharged by boiling water and then activated at a later date when needed.

If you are contemplating a Solar DHW or Hydronic Space Heating System, consider using a sodium ethoanate backup storage system that can be made to work with the evacuated tube type of thermal solar collector.

Such a system would save extra solar heat on sunny days to use on cloudy or sunless days.

The storage would be composed of an extra water tank filled with sodium ethanoate trihydrate (sodium acetate trihydrate), or hydrated crystals of sodium acetate. If the solid crystals are heated with heat from Solar Thermal EVAC tubes, to the boiling point of water, the water molecules will be released from the crystals. This freed water can then dissolve the sodium acetate.
After cooling, the sodium acetate remains dissolved even though the solution is supersaturated.

This means that the energy that was required to release the water molecules from the crystals and dissolve the sodium acetate into that water still remains in the system even though the temperature has dropped.
Then, when backup heat is needed, a small seed crystal is injected with a trap door, or an automatic small air pressure pump gun. The seed crystal triggers the crystallization of the sodium acetate trihydrate.

When the crystals form, the magically stored past energy that was required to initially dissolve them is then released. This release of energy raises the temperature to 129.2 °F, or 54°C, which is an ideal domestic hot water temp
-erature!

It is also very close to what is needed for bioDiesel tranesterification!

Technically, this is heat that is released during a phase change....an exothermic chemical reaction.

The process is theoretically repeatable indefinitely, although the seed crystal gun, or small sodium ethanoate trihydrate seed crystal supply, will need occasional replenishment.


http://jchemed.chem.wisc.edu/JCESoft/CCA/CCA3/STHTM/ACETATE/ACETAT1.HTM

http://www.howstuffworks.com/question290.htm

http://static.howstuffworks.com/mpeg/q290.mpg

 

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