A method for evaluating the heat and mass transfer characteristics in a reversibly used water cooling tower (RUWCT) for heat recovery

In sub-tropical regions, a standard water cooling tower may be reversibly used, as part of a desuperheater heat recovery system for service hot water heating, to extract free heat from ambient air in colder seasons when building cooling load is reduced. Chilled water is pumped into a reversibly used water cooling tower (RUWCT) where it is heated by warmer ambient moist air. This paper presents a method by which the heat and mass transfer characteristics in a counter-flow RUWCT can be evaluated. The method is developed by introducing to the Merkel's equation for standard water cooling towers the revisions that account for the differences in heat and mass transfer characteristics between a water cooling tower and a RUWCT. Field experimental results from a RUWCT installed in a sub-tropical region in China indicated that the method developed could be used to evaluate the thermal performance of a RUWCT with an acceptable accuracy.