[Objective] This study aims to investigate the anti-freezing performance of indirect air-cooled towers under severe winter conditions and ensure the safe and economical operation of thermal power plants. [Methods] A mathematical model of the critical anti-freezing system for windward air-cooled triangular units was developed based on computational fluid dynamics. By coupling a porous media model with the distributed parameter method

a partitioned quantitative analysis of the heat transfer characteristics on the windward and leeward sides was conducted. The study determined the critical circulating water velocity and critical louver opening for the cooling cell under various ambient wind speeds

ambient temperatures

and inlet water temperatures

revealing the variation trends in sector heat transfer performance under critical conditions. [Results] The results indicate that the outlet water temperature of each section continuously decreases along the flow direction. On the leeward side

the temperature difference across sections initially increases slowly before decreasing

while on the windward side

it gradually decreases. A decrease in the radiator inlet water temperature

a decrease in ambient temperature

and an increase in wind speed all contribute to a higher freezing risk for the tube bundle. This leads to an increase in the critical water velocity and a decrease in the critical louver opening. As the inlet water temperature rises

the critical water velocity first decreases rapidly and then stabilizes. The influence of ambient temperature on the critical circulating water velocity is more pronounced under low inlet water temperature conditions. For example

at an ambient wind speed of 7 m/s and an inlet water temperature of 5 ℃

the critical velocities are 2.27 m/s and 10 m/s at ambient temperatures of-10 ℃ and-35 ℃

respectively. Under conditions near the critical water velocity

the heat transfer coefficient is higher for windward sectors than for leeward sectors. On the leeward side

the coefficient first increases and then decreases

while on the windward side

it first decreases and then increases. Under conditions near the critical opening

a larger critical opening corresponds to a higher heat transfer coefficient

with the windward side exhibiting a greater value than the leeward side. When the opening is further reduced

approaching a fully closed state

the heat transfer coefficient gradually decreases. Both the windward and leeward side coefficients show a trend of initially decreasing and then increasing. [Conclusion] In conclusion

this study provides a detailed analysis of the critical anti-freezing operational parameters for windward cooling cells

offering valuable insights for the anti-freezing design and operational strategy development of similar indirect air-cooled systems in cold regions.