Abstract: The environmental wind has significant influence on the heat transfer performance of direct air-cooled condenser. In order to more accurately analyze the influence of spray humidification system on the heat transfer of air-cooled condenser, three-dimensional numerical simulation was carried out on a 300 MW direct air-cooled unit by using two-step modeling method, based on the standard k－ε turbulence model and the discrete phase model. Considering the influence of wind speed on the effect of spray humidification during the simulation process, the method of increasing the nozzle's water spray quantity was proposed to solve the problem that the entry temperature of air-cooled unit was higher because of the environmental wind. The result shows that under the dominant wind direction with wind speed of 9 m/s, the entry temperature of the air-cooled unit at platform edge is 6.4 ℃ higher than those of other air-cooled units. The increase of the nozzle's water spray quantity can lower the exit temperature of the heat exchanger in the air-cooled unit at platform edge, so that the whole exchange efficiency of the unit is increased. Taking the wind of 9 m/s as an example, after the increase of the nozzle's water spray quantity, the back pressure of the unit is 5 kPa lower than before.

Key words: direct air-cooled condenser, spray humidification, numerical simulation, step model