FAN PERFORMANCE IN AIR-COOLED STEAM CONDENSERS

It has in recent years been found that air-cooled steam condensors consisting of arrays of A-frame heat exchanger units, incorporating axial flow fans, have not been performing satisfactorily at a number of power plants. Subsequent tests have shown that the cooling air flow rate was inadequate in certain cases. In part this was shown to be due to an underestimation of the losses experienced by the air stream flowing through the A-frame unit. An analysis is presented in which the various losses are identified and a numerical example is given that clearly illustrates the significance of so-called ''secondary losses'' in a practical air-cooled condensor unit. It is shown that the sum of the ''secondary losses'' may be of the same order as that of the heat exchanger bundles under normal flow conditions.