The Vapor-X cooler is based around the fact that as you increase the temperature of water, it evaporates more rapidly, turning from a liquid into a gas. During this state transition, the water releases its latent heat into the surrounding atmosphere, thereby cooling the object from which the water is evaporating. This is why sweating cools your skin so effectively.
Heatpipes already use this evaporative cooling phenomenon, but while heatpipes require coolant to be forced in one direction along a set path, vapour chambers allow the heat to be transferred in all directions. You could think of them as a large-diameter, flat heatpipe, with the liquid moving through the layers of the chamber, rather than travelling along a restrictive pipe.
A vapour chamber is composed of three distinct layers: the transportation wick, the vaporisation wick and the condensation wick (see the explanatory pictures by clicking on the picture above). A wick is a material that can draw in a liquid by capillary action (think of a sponge absorbing water), but other than that, the names of the layers are pretty self-explanatory. Pure water is heated while in the transportation wick, and as it turns to gas, it moves into the condensation wick. Away from the heat source, the water condenses back into a liquid and travels back to the transportation wick by way of capillary action, ready for the process to begin again.
The air pressure is lowered in a vapour chamber, as a lower air temperature lowers the boiling point of the water, making the transfer of heat more efficient.
http://www.bit-tech.net/custompc/features/602193/vapour-chamber-cooling-explained.html
