How to make ice using the principle of evaporation cooling? SolCool consists of a water cup, a reservoir of a special water-absorbent zeolite - a substance used as a water-softener in washing powders - and a connected vacuum pump. The cooling system exploits three physical phenomena:
The boiling point of a fluid - here water - is dependent on the pressure above it. At 20° C water starts to boil below a pressure of 20 mBar.
Water evaporation needs heat, the latent heat of vaporization. During this process this heat is taken from the liquid water, which consequently cools.
Zeolite absorbs water-vapor from damp air.
So by combining these three phenomena, a cooling device can be built. The pump is used to reduce the device's internal pressure, making the water boil, which cools the remaining water. As long as the pressure is progressively reduced and the connected zeolite reservoir is able to adsorb the water vapor, the water will keep on evaporating and the cooling process will continue. Within a few minutes the system is able to produce about 100 milliliters of ice. The zeolite can be re-activated by drying in your oven or alternatively with our Solar cooker FocusMirror110Kit.