how water cooled in water pot !! - The thermodynamic Approach

Clay water pot are use as water container and also used to cool water from centuries. Without any effort, temperature of water inside pot can be naturally reduced by some temperature.

Thermodynamic-ally in water cooling process, mass transfer is comparatively more important than heat transfer. Clay water pot has a porous structure, hence it can be imagined as a clay boundary with a very small holes. Due to very small holes, capillary action take place in water pot surface and this is also reason why many water droplets appear at pot surface and surface remain wet all the time.

Due to capillary action, even even if temperature of water is less than temperature of atmospheric air, effect due to higher concentration of water in pot, it will move from higher concentration to lower concentration (atmospheric air).

In simple terms, due to capillary effect, inner water particles will reach to the surface by taking energy from all neighbor hood droplets, and then get evaporated to the atmosphere (because atmospheric air is unsaturated).

evaporation of water to unsaturated atmospheric air

Due to continuous transfer of energy to the surface particles, enthalpy of water (water inside pot) decrease (hence temperature also decrease) and amount of water also decrease because molecules are continuously evaporated to local atmospheric air.

For this process, atmospheric air must be unsaturated. And this process will continue until the local atmospheric air saturated. That's reason why in summer it gives the best results compare to winter and monsoon.

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