Thermal storage with water vapour?
published: 03/11/22, 20:26
Hello,
Like some of us I looked for heat storage solutions. While studying PCMs (Phase Change Materials) I noticed that the latent heat of passage to the vapor state of water was high:
To change 1000 g of water from the state of ice to that of water it takes 335 kJ
To heat 1000 g of liquid water at 0°C to 100°C requires 419 kJ
To convert 1000 g of liquid water at 100°C to vapor it takes 2257 kJ
It therefore takes 5.4 times more energy to turn water into vapor.
enough to raise its temperature by 100°C.
Would it then be possible to use this fact to store thermal energy by evolving
a volume V of water around its vaporization temperature?
I also saw that the boiling temperature of water decreases with the pressure while its latent heat increases with this decrease, this could make it possible to work at a lower temperature (for example, at 0.2 bar the water boils at 60°C and at the same temperature its latent heat of vaporization became 2360 kJ/kg).
http://pravarini.free.fr/Images/Teb.jpg
http://pravarini.free.fr/Images/ChaleurLatente.jpg
One could then think of storing heat in an instrumented (pressure, temperature) and thermally insulated tank containing water whose temperature would oscillate around the boiling point. I know that on an industrial scale there are vapor accumulators. Are there equivalent systems for individuals? couldn't we build such a system ourselves? (pressure cooker...)
Like some of us I looked for heat storage solutions. While studying PCMs (Phase Change Materials) I noticed that the latent heat of passage to the vapor state of water was high:
To change 1000 g of water from the state of ice to that of water it takes 335 kJ
To heat 1000 g of liquid water at 0°C to 100°C requires 419 kJ
To convert 1000 g of liquid water at 100°C to vapor it takes 2257 kJ
It therefore takes 5.4 times more energy to turn water into vapor.
enough to raise its temperature by 100°C.
Would it then be possible to use this fact to store thermal energy by evolving
a volume V of water around its vaporization temperature?
I also saw that the boiling temperature of water decreases with the pressure while its latent heat increases with this decrease, this could make it possible to work at a lower temperature (for example, at 0.2 bar the water boils at 60°C and at the same temperature its latent heat of vaporization became 2360 kJ/kg).
http://pravarini.free.fr/Images/Teb.jpg
http://pravarini.free.fr/Images/ChaleurLatente.jpg
One could then think of storing heat in an instrumented (pressure, temperature) and thermally insulated tank containing water whose temperature would oscillate around the boiling point. I know that on an industrial scale there are vapor accumulators. Are there equivalent systems for individuals? couldn't we build such a system ourselves? (pressure cooker...)