Numerical investigation of hot air recirculation of air-cooled condensers at a large power plant

In order to minimize the hot air recirculation (HAR) to ensure normal operation of the air-cooled condensers (ACC) system, the hot air recirculation phenomenon and its dependence on ambient winds are numerically simulated by using the computational fluid dynamics code, FLUENT. Under the constant ambient temperature, the effects of different wind speed and wind direction on the HAR are qualitatively considered by applying the concept of the hot recirculation rate (HRR). The mechanism of occurrence of hot air recirculation are presented and analyzed. It was found that when considering about the existing and normally operating power plants, the HAR is more sensitive to wind direction and wind speed. Based on the above results, two improved measures increasing the wind-wall height and accelerating the rotational speed of the fans near the edge of the ACC platform are developed to effectively reduce the hot air recirculation.