Performance prediction of a prototype closed-wet cooling tower

CFD (computational fluid dynamics) is used to predict the thermal performan ce of a small closed-wet cooling tower to generate cold water for chilled c eiling systems. The CFD technique involves the simulation of two-phase flow of gas and water droplets. Certain simplifications are made with regard to the cooling device to overcome limitations in the CFD software employed. F or example, the tubes for the heat exchanger are considered to be independe nt entities with a uniform surface heat flux. The simulated thermal perform ance is compared with experimental measurement. It is shown that the therma l performance of the cooling tower can be predicted when chilled water in t he heat exchanger flows at the design rate. However, when the flow rate of chilled water is much lower than the design value, in order to predict the thermal performance, appropriate measures are required to compensate for th e simplifications so that air flowing through the heat exchanger is not ove r-saturated.