Investigation of the performance of cold-end system in direct air-cooled power units under the influence of ambient winds

Abstract

Direct air-cooled condensers in power plants rely on heat transfer with the atmospheric environment to discharge thermal energy. The heat transfer process becomes complicated in practical operations when ambient wind is involved. To examine the impact of wind on the heat transfer performance of direct air-cooled condensers, this paper took into consideration three different wind directions, namely, headwind, crosswind and tailwind, as well as four different speeds (3 m/s, 6 m/s, 9 m/s, and 12 m/s), and numerically investigated their influences on the thermal performance of a 600 MW direct air-cooled power unit. The variation in ventilation rates and inlet air temperatures among the cells under the influence of ambient winds are also studied. Simulation results indicated that ambient winds induced thermal air re-circulation and air backflow phenomena in the air-cooled island. The cells located on the windward side were significantly affected in all three wind direction conditions. The ventilation rates and inlet air temperatures among the cells were not uniform, showing an overall increasing trend. In particular, negative pressure zones were generated under tailwind conditions, severely impacting air-flow rates at the fan inlet, and inlet air temperatures of cells. These phenomena became more pronounced with increasing wind speeds.