Desuperheater heat recovery hot water heating systems in subtropics: Using water cooling towers to extract heat from ambient air as heat source

In subtropical regions, using desuperheater heat recovery hot water heating systems is commonly seen. However, there may be insufficient heat to recover from an air-conditioning system in cold seasons due to buildings' reduced cooling loads. A standard water cooling tower may then be operated in a reverse mode to extract heat from ambient air, as part of a heat source for water heating, so that a backup heating provision may be eliminated. This paper describes a number of actual installations of desuperheater heat recovery hot water heating systems with cooling towers, operated to supply heat in subtropical regions in China, and reports on the on-site measured operating performance of such a heat recovery system.