Flow and heat transfer characteristics of air-cooled island in direct air-cooled units under ambient wind and spatial layout effects

To approach the practical operation of multiple unit combinations in engineering, this paper focuses on the air-cooled island of a 4×660 MW direct air-cooled unit in Northwest China, examining how increasing the distance between the air-cooled island and buildings, as well as raising the height of the air-cooled platform, affects its flow and heat transfer characteristics. The results indicate that downwind is the most unfavorable direction, and under all wind directions, the fan inlet temperature increases with ambient wind speed. Under ambient wind, edge air-cooled cells are significantly affected, showing reduced fan inlet flow, enhanced inlet negative pressure, and prominent vortex phenomena. Increasing the distance between the air-cooled island and buildings by 10 m from the original distance leads to a 21.96% decrease in leeward fan inlet temperature, a 26.5% increase in flow rate, and significant improvements in heat flux and heat dissipation of air-cooled unit, with the improvement slowing down upon further outward movement. Raising the air-cooled platform by 6 m results in a 22.45% reduction in corresponding leeward fan inlet temperature, a 26.11% increase in flow rate, and a 22.8% rise in unit heat flux, while the improvement rate diminishes when the height exceeds 6 m. This study reveals the coupling mechanism between ambient wind and the spatial layout of the air-cooled platform, providing a theoretical basis for layout optimization and operational regulation of air-cooled island in direct air-cooled unit.