A heat transfer system is provided having an air-cooled heat exchanger system. The heat exchanger system has an evaporator, condenser, compressor and a fan for forcing air over a heat exchange surface for effecting heat transfer. A mist generator having at least one nozzle directs a stream of fine mist or atomized liquid coolant into the air. The mist generator is coupled to a supply of liquid coolant. A controller controls the degree of mist or atomized coolant generated by the mist generator. A filter element positioned between the at least one nozzle and the heat exchange surface captures droplets of liquid coolant. The at least one nozzle is spaced apart from the filter element for directing the stream directly into the air surrounding the filter element.