Cooling systems for comfort, refrigeration, and industrial applications typically utilize one of three primary methods for heat rejection — air cooled, water cooled, or adiabatic. Hybrid cooling, rejection of heat using two or more of these methods, has also gained popularity in recent years. To choose the optimal cooling system, engineers must consider the climate, desired operating cost, water availability, cooling load, and any other potential site-specific objectives and constraints (e.g., maintenance).
Air-cooled systems use dry cooling. Air passes over a finned heat exchanger containing the process fluid. Sensible heat is transferred from the process fluid in the heat exchanger to the airstream flowing through the unit. To efficiently cool the process fluid to the desired temperature for the system, the dry bulb temperature must be significantly lower than the fluid temperature. In hot climates and during periods of high ambient temperatures, this technology results in higher process fluid design temperatures and lower overall system efficiencies.