Has a vaccuum chamber ever been used for desalination?
Has a vaccuum chamber ever been used for desalination?
I under stand that the lower the air pressure, the lower the boiling point of water. Also, some primitive desalination kits are basically evaporators.
Could you make a really big tank without a bottom and paint it black. Then, submerge it partly in the ocean . Pump the air out of the top. The water would rise up into the tank, a bit, but not all the way.
You wouldn’t need to have a perfect vacuum, just lower the air pressure enough to make boiling easier. Let the sun heat the black tank, and viola, steam.
Collect that steam from the air you are pumping out of the top of your tank, and you’ve got fresh water, right?
Edit: nevermind. Found it on google. Leaving this here to display my shame.
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I could be wrong, but iirc even tho you can boil the water at lower temperature, it still takes the same amount of energy to change phase, so the efficiency gain isnt as spectacular as you might expect.
The energy to change phase, the latent heat of vaporization, does decreases. Enough such that the ambient temperature is able to supply sufficient heat for vaporization (that is, boiling). The latent heat of vaporization is temperature and pressure dependent for most materials.
Akshuly, the charts I can find on the subject of enthalpy of vaporization vs pressure say the opposite- it increases at lower pressure
I could have gotten it backwards. Depends on how the system is being defined and which direction the heat is going.
I do agree that at some point ambient temperature does the job, which is obviously super convenient.