Abstract: An evaporative cooling system is disclosed which uses a heat pipe device comprising first and second heat exchangers to transfer heat from the space being cooled to an evaporative cooler. Evaporative cooling is produced by passing atmospheric air over wet pads and the first heat exchanger. Evaporation of water removes heat from the atmospheric air and from the first heat exchanger containing refrigerant vapor, causing condensation of a portion of the vapor. The condensate moves to the second heat exchanger which contains liquid refrigerant. Room air is passed through the second heat exchanger and gives up heat to vaporize the liquid refrigerant. Vaporized refrigerant moves to the first heat exchanger where it is condensed as previously described. The cooled atmospheric air is then used to cool the condenser of a vapor compression machine, the evaporator of which is located in the flow path of the room air downstream of the heat pipe, further cooling the room air to desired conditions.

Abstract: The system in the present invention includes HVAC unit, such as an air-conditioner, having an evaporator coil, and a heat exchanger for drawing heat from air entering the inlet side of the air-conditioner evaporator and supplying heat to air at the outlet side of the air-conditioner evaporator. The heat exchanger is a phase change heat pipe-type heat exchanger, having a evaporator before the air-conditioning evaporator and a condenser after the air-conditioner evaporator.