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
Back
To Solar Capture Tubes
