The heat pipe, which was invented in 1942 by an automotive engineer, did not find application in the heating, ventilating, and air-conditioning industry as a passive air-to-air heat recovery device until the early 1970s. Over the last several years, the heat pipe has found new application as a dry type or indirect evaporative cooling component in large cfm built-up and packaged air-conditioning systems for arid climates. A spray coil technique is employed on the "wet" side of the heat pipe to produce a dry cooling effect on the makeup air side. The use of this system technique for constant-volume multizone as well as variable-air-volume systems will be examined. The performance of the heat pipe for indirect evaporative cooling in the summer as well as heat recovery in the winter will be analyzed. The location of the heat pipe in an economy cycle position in order to increase outdoor air quantities for VAV systems will be discussed. System costs and potential summer and winter energy savings will be developed.

Units: I-P