Abstract: A water cooling system for showers has a water tank filled with water to be cooled, and a heat exchange loop which includes an internal heat exchange (HX) evaporator immersed into the water within the water tank, and a condenser HX unit positioned externally above the internal evaporator unit. A refrigerant in the loop absorbs the heat from the water in the water tank, circulates in the HX loop, and passes to the condenser HX unit to release heat to ambient air. The water cooling process is passive and does not require any form of external energy. The subject heat transport attains a minimal thermal resistance by two-phase evaporation and condensation process (heat piping) which achieves positive flow at as low as 0.2° C.-1° C. temperature difference between the ambient air and the tank water.

Abstract: A water cooling system for showers has a water tank filled with water to be cooled, and a heat exchange loop which includes an internal heat exchange (HX) evaporator immersed into the water within the water tank, and a condenser HX unit positioned externally above the internal evaporator unit. A refrigerant in the loop absorbs the heat from the water in the water tank, circulates in the HX loop, and passes to the condenser HX unit to release heat to ambient air. The water cooling process is passive and does not require any form of external energy. The subject heat transport attains a minimal thermal resistance by two-phase evaporation and condensation process (heat piping) which achieves positive flow at as low as 0.2° C.-1° C. temperature difference between the ambient air and the tank water.