Numerical study on performance improvement of air-cooled condenser by water spray cooling

Water spray cooling is an efficient way to enhance heat transfer of the air-cooled condenser (ACC) of power generating unit under high ambient temperatures. Taking the air-cooled 300 MW power generating unit as object, the flow and temperature fields of ACC with water spray cooling were analyzed by numerical simulation with experimental validation. Based on the air flow field inside ACC cell, an improved water spray nozzles arrangement was proposed to enhance the cooling capacity. The inlet air temperature and back pressure of turbine were compared with that under the original nozzles arrangement. The water consumptions including that of water droplets pre-cooling evaporation in air flow, liquid film evaporation on the finned tube bundles, and drainage of redundant water were obtained. The influences of water spray rate, spray direction and nozzles distance on cooling performance were investigated. The results showed that the improved nozzles arrangement is expected to provide efficient cooling performance and significant reduction in back pressure of the objective power generating unit. The improved nozzles arrangement with upward spray direction and nozzles distance of 0.8 m can be applied to the design of water spray system in ACC. In addition, the obtained redundant drainage water under various ambient conditions provided the evidence for spray water rate optimization.