In air-cooled condensers, the volum

In air-cooled condensers, the volume flow of cooling air per unit of total heat rejection is600 to 1200 cfm/ton of refrigeration capacity at the evaporator, and the optimum value is about 900cfm/ton. The corresponding cooling air temperature difference — cooling air leaving temperature minusoutdoor temperature (Tca.l – To) — is around 13°F.The condenser temperature difference (CTD) for an air-cooled condenser is defined as the differencebetween the saturated condensing temperature corresponding to the pressure at the inlet and the airintake temperature, or (Tcon.i – To). Air-cooled condensers are rated at a specific CTD, depending on theevaporating temperature of the refrigeration system Tev in which the air-cooled condenser is installed.For a refrigeration system having a lower Tev, it is more economical to equip a larger condenser with asmaller CTD. For a comfort air-conditioning system having a Tev of 45°F, CTD = 20 to 30°F. QrejUconAconTmmhhqPrrlcommo=∆=60()−′=+()254523oη morh′3FQqPqrejrejrlcomrlmo==1+(2545)(η) VQocau.rej/Air-Conditioning and Refrigeration