Out of curiosity,

What would be the best setup to evaporate as much seawater as possible in using the propane from a 1kg tank?

Will it be,

  1. Big pan, boil them all at once
  2. Small wide pan, boil them a bit everytime (without removing salt from pan)
  3. Small wide pan, with separate hot air feeder

My hypothesis the third would perform best,

Since in 2nd setup, even with increased surface area, pouring cold water to the pan will decrease the pan's leftover temperature from previous iteration. Thus require more energy to heat the pan again

Planning to make some experiment soon to find out

What do you think? Or i am thinking it all wrong?

  • $\begingroup$ whwat does this mean: "as much seawater as possible in 1kg propane tank?" The seawater is in the tank? Are you pouring it from this tank into a pan? And what is the "without extracting salt" comment? If you boil away seawater you will be left with salt. $\endgroup$
    – Tiger Guy
    Oct 11, 2021 at 12:47
  • $\begingroup$ Are you in a sunny country? Use solar energy to heat… $\endgroup$
    – Solar Mike
    Oct 11, 2021 at 14:57
  • $\begingroup$ Sorry for the confusion, i should be better phrasing the sentence. 1) "1kg Propane tank" is tank with 1kg liquid propane (LPG) in it 2) Whenever first small batch of seawater fully evaporated, the next batch is poured directly into the wide pan "without extracting (leftover) salt (from previous batch)" @TigerGuy $\endgroup$
    – Lorenz
    Oct 11, 2021 at 14:58
  • $\begingroup$ I am not. Otherwise this question won't be necessary.. @SolarMike $\endgroup$
    – Lorenz
    Oct 11, 2021 at 14:58
  • 3
    $\begingroup$ recover heat from the steam ... do not use an open pan $\endgroup$
    – jsotola
    Oct 11, 2021 at 17:29

1 Answer 1


Since the amount of energy per unit volume required to evaporate (or boil, depending on your desire for speed) the water is a constant, the only things to control are, roughly:

  1. efficiency of heat transfer from the propane burner head into the water
  2. insulating the "boiler" so that the energy does not leave the water other than via evaporation.

There are secondary considerations, such as not bringing the water to such a "rolling boil" that some of the steam expelled is at a temperature greater than 373 Kelvin, which would be a waste of energy.

update: thanks to @jstola for pointing out that an energy recovery system such as a condenser which extracts heat from the steam would be really helpful.


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