Sodium acetate as a thermal buffer?

[Christophe]

the real question is that this principle of heat storage is interresing for a big energy?

No, the real question is: how much does it cost per ton! finally stored kWh ...

And secondly: how many times can we regenerate it ...

[chatelot16]

that's what I meant ... is this financially interesting

it seems a little weak, and not at all: if the exothermic rection begins it spreads quickly to all the volume: not very practical to make bigger than a chauferette ...

if the goal is to store the heat of the sun I prefer that the sun separates 2 produces, which will produce heat when we mix

[Christophe]

Ben in my opinion it is much less interesting econologically (and even physically, I did not do the calculations) that palm oil: https://www.econologie.com/forums/stocker-de ... t7421.html

[chatelot16]

atention: the thermal storage in palm oil or in water has a limited duration, the heat is lost with the time and the bad insulation ...

effective chemical storage is not lost over time: you can spend all summer accumulating the sun, store it safely and use it when it's needed in the middle of winter

finally have to find something with a density of energy a little better

[Christophe]

Good point Chatelot, remains to find a cheap chemical storage stored kWh ... and the most natural possible ...

[dedeleco]

Not solved because the volume needed is important and its price even higher than the energy density is high!
The limit is that of fuel or gas (or wood) to spend the winter, about 1500 2000 € per year for a typical house 70 years 90! The investment is therefore limited to 20000 to 40000 € on 10 to 20 years.
fuel, 3 tons, to synthesize with the sun, but irreversible reaction, CO2 and H2O in the end to give plants or algae on large surface giving back oil or wood !!
Calculate for different products really reversible as this acetate or a reversible chemical reaction in the cycle (very many in fact with water for example, NaSO4 for example, lime etc. ..) that use low energy reactions or hydration water, in fact, at low temperature less than 100 ° C, typically 100 times less energy than fuel oil, and therefore it takes 300m3 of the product, comparable to the volume of earth or water to be heated insulated by 1m of good insulation, even 3m of earth (in this case the price is minimum) !!
The more the reaction is energetic with a low volume, the higher the temperature will be high such as lime (900 ° C and cheap) which requires full sun with dish!
It is better to measure how cheap fuels are !!

In summary compact, the fuels have per molecule an energy of 1eV (11600 ° K) and the transitions of phases to T ordinary as with water, 100 to 300 ° K, to little 100 times lower, and therefore the volume needed is 100 times more, a very large pool 300m3.
http://en.wikipedia.org/wiki/Electronvolt

So, the problem is not in finding the product and the reaction (an armada), but in decreasing the volume necessary, by decreasing the losses of the house to the max by isolating it to the max, and recovering the solar energy from the winter to the max, (almost passive house), which is very difficult for a house old typical modern !!!

In my opinion, storing the heat of summer in the deep earth over a volume of several hundred m3 by drilling boreholes seems to me the simplest.
It would be necessary to design a robotic percussion drill that pulls a pipe into the earth in a small hole of a few cm, because then more drilling cost problem !!

http://fr.wikipedia.org/wiki/Sulfate_de_sodium

Glauber salt, the decahydrate form, was used in the past as a laxative. It has also been proposed to store heat in passive solar heating systems. This use takes advantage of its unusual solubility properties, as well as its high heat of crystallization (78.2 kJ / mol).
In 1995, sodium sulfate was sold around 70 $ per ton in the United States, making it a relatively cheap chemical compound.

[dedeleco]

Good cheap material with 1155KJ / Kg
http://fr.wikipedia.org/wiki/Chaux_%28mati%C3%A8re%29
http://fr.wikipedia.org/wiki/Oxyde_de_calcium

concretely illustrating the problem: big energy requires heating a lot but less product!
Lime requires 900 ° C !!

[chatelot16]

lime is a good way to use solar heat: limestone is not expensive, just dig in the right place

the quicklime produced can be stored easily and for a long time: and it is as useful for construction as for heating

interesting application: moisture absorber: quicklime not only absorbs moisture but heats up at the same time!

alas not easy to use, because if the quicklime goes in dust is a little dangerous ...


another reaction of the same kind: the calcium chloride: it must be heated very strong in the sun for the dehydrate: then it makes an exothermic moisture absorber, less strong than lime but without danger

another solar heat absorber very effective but more complicated: heat 1200 ° lime and charcoal: it is calcium chloride, easy to store ... then just pour water on it make acetylene the most powerful fuel!

I will have to do it someday because my stock of calcium carbide that I went to seek at Pechiney Ugine Kulman Bellegarde on Valserine is soon exhausted and this factory no longer exists ...

[Christophe]

The heater regenerates without problem in a few hours on a wood stove provided it is placed close enough to the stove but not too much so as not to damage the "silicone" pocket?

The whitened and hardened crystals become liquid and translucent again after a few hours of heating, here is the heater at the start of the "regeneration":



We will also count the number of possible cycles and make a small video, you will see it is quite impressive the speed of the crystallization when we crack the "catalyst" pellet ...

[Christophe]

Well it took a lot less time than I thought, less than 1h30 (1h between 2 photos).

The 1ere regeneration on the stove I had left the night without watching. I remind you that the manual spoke of 10 min 15 in boiling water (simmering).



We notice small bubbles (beginning of boiling?) In the product ...

At the level of T °, ​​it is approximately 80 ° C for the pocket:



While we are at 130-140 ° C at the stove surface at this location:



Measurements made with this excellent 3 1 thermometer: https://www.econologie.com/shop/thermome ... p-326.html

We are therefore 2 pellet cracking and 2 house regenerations (+1 in "factory"?).