Anti-freezing of air-cooled heat exchanger by air flow control of louvers in power plants

Air-cooled heat exchanger will take a serious freezing risk in cold winter, especially at a strong wind speed. Therefore, it is of great concern to study the anti-freezing of natural draft dry cooling system in power plants. In this work, the flow and heat transfer models of cooling air coupling with the circulating water heat transfer are developed and numerically simulated based on the anti-freezing requirement that the outlet water temperature of each sector in the air-cooled heat exchanger remains above 0 °C. The air flow control by the louvers for the anti-freezing of air-cooled heat exchanger is investigated, where the louvers are modeled as porous jump faces. The velocity, pressure and temperature fields are presented, and the opening degree of the louvers in each sector, inlet air temperature and mass flow rate of each sector, outlet water temperature of air-cooled heat exchanger, and the turbine back pressure at various wind speeds and ambient temperatures are obtained. The results show that the opening degree adjustment of the louvers can effectively prevent the air-cooled heat exchanger from freezing in cold days, which is beneficial to the safe and economic operation of natural draft dry cooling system in power plants.