直接空冷机组空冷岛加装曲面下挡风墙的数值模拟

Numerical Simulation Research of Fixing Lower Windbreak of Surface upon Air-cooled Island of a Direct Air-cooled Unit

以某600 MW直接空冷机组为例,利用CFD软件对其空冷岛外部流场进行数值模拟。分析了不同风速对直接空冷凝汽器换热效率的影响。指出了在风速大于7 m/s时,空冷凝汽器换热效率的降低是热风回流与"倒灌"现象综合作用的结果。提出并分析了在空冷岛不同部位加装下曲面挡风墙对空冷换热效率的影响。计算结果表明,在空冷平台四周的外沿加装下挡风墙,空冷凝汽器的平均换热效率可提高14.43%。若将迎面风的曲面下挡风墙加装在第一排风机与第二排风机之间,其平均换热效率较加装在外沿可提高4.8%,并对曲面的不同曲率对空冷凝汽器换热效率的影响进行了研究,为进一步完善空冷岛的结构设计提供了理论依据。

The numerical simulation of the external flow filed of the air-cooled island was made with CFD for a 600 MW direct air-cooled unit.And the effect of the different wind speed on the heat transfer efficiency of direct air-cooled condensers was analyzed,the results shows,when the wind speed exceeded 7m/s,that the main reason of the heat-transfer efficiency fall in the air-cooled condenser is due to the combined action of the hot air recirculation and its downdraught.In the paper,the effect of the lower windbreak of surface located in different position in air cooling island on the heat transfer efficiency was further analyzed,the results shows,that the mean heat transfer efficiency increase 14.43% when the lower windbreak of surface situated in the outer brim all around the air cooled platform.The mean heat transfer efficiency of the air cooled condenser would increase about 4.8%,the lower windbreak for the incident wind was set between the first row fans and the second row fans,than the efficiency when the lower windbreak was located in brim.And study the effect of different surface curvature of the lower windbreak to the heat exchanger efficiency of the air-cooled condensers.The research results provide some theory evidence for the structural design and optimization of the air-cooled island.