Conception of heat storage with Na2-SO4?

[ovacs]

Hi,

Who could evaluate my conception of heat storage with Na2-SO4?

Idea:
Dry Na2-SO4 is moistered with water till max energy release (solvation energy?)
Has there been now Na2-SO4-10H20 produced?
Can this compound be regenerated (dried) with heat supply (sun radiation?) to dry Na2-SO4?


thanks taking time
Johann

 

[NobodySpecial]

It's possible but something losing and gaining water is a bit tricky to engineer
Most systems using something going between liquid and solid form.

I think the small personal ones use Sodium Acetate - don't know what you would use on an industrial scale.

 

[ovacs]

Thanks for your bringing Natrium Acetate. As a result, there are many other alternatives i found as gypsum, activated carbon. But it is challenging to bring any of them to a competitive technique as all are limited in capacity.

 

[MagnetDave]

There is nothing conceptually wrong with what you describe. Heating up a hydrated crystal will drive the water off and make it anhydrous. I'm not sure how you make any of that useful, but your understanding of the chemistry is sound.

 

[NobodySpecial]

As a result, there are many other alternatives i found as gypsum, activated carbon.

There is even a natural solution. Some pine tree (southern yellow pine?) has a sap that melts somewhere just below room temperature (15-20C) taking in energy and freezes below this temperature, thus giving out energy - natures air conditioner!
There were some people building homes in the US out of this - you need quite a lot obviously - I think the plan was basically log cabins with lots of insulation on the outside.

Your plan to hydrate a salt is workable as MagnetDave said, it's just a bit tricky to deal with the hydrated <-> crystal change in an engineering sense.
How do you collect the released water without using lots of power and how do you keep the resulting crystal in a compact form while still allowing water to get back into it? You also have to consider how corrosive / toxic the material is - it's no use having a free source of energy if you need some super expensive stainless steel or titanium alloy to contain it.

 

[ovacs]

After some evaluation, natrium-sulfate is not any more a prior material for storaging sun energy. Actually, sodium-acetate would fit better due to its higher melting point of 58°C.
However, before looking closer into sodium-acetate, i focus more on gypsum and second on activated carbon. Related features of gypsum have been described within a patent in the 80's. As a result, there are sufficient data about gypsum in regard of heat storage and release but not yet from activated carbon run with water. If someone knows how to approache such a thermo-chemical cycle with activiated carbon and water at atmospheric conditions, that would be helpful. Thanks

 

[Borek]

I remember reading about using magnesium sulfate heptahydrate for the same purpose.