多孔介质模型在300MW空冷岛下挡风墙中的应用

The Application of Porous Media Model in the Lower Windbreak of 300MW Air-cooled Island

以某300MW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。分析了不同结构形式的下挡风墙对空冷凝汽器换热效率的影响。指出了在风速大于6m/s时,空冷凝汽器换热效率的降低是"倒灌"现象与热风回流综合作用的结果。计算结果表明,在空冷平台四周的外沿下方加装直面下挡风墙后比不加时换热效率提高了12.1%,加装面积比为1:1.73、夹角为90°的多孔折面下挡风墙后,空冷凝汽器的平均换热效率比加直面实心挡风墙提高了2.1%,更加有利于凝汽器的换热。为进一步改进空冷岛的结构提供了理论依据。

Based on the research of 300 MW direct air-cooled unit, we make numerical simulation of the external flow filed of the air-cooled island was made with CFD, and analyze the effects of lower windbreak in different situations on the direct air-cooled condensers. As the result shows, the fall of the air-cooled condenser efficiency is the result the downdraught and hot air recirculation. And the result also shows that the mean heat transfer efficiency increase 12.1% when the lower windbreak situated in the outer brim all around the air cooled platform, however, if the porous lower windbreak, with 1.73 times bigger in area than the direct lower windbreak, is situated with an angle of 90~ in the outer brim of the air cooled platform, the average heater transfer efficiency increases 2. 1%, which is more conducive to the heat transfer of he condenser, and also provides theory evidence for the structural improvement of the air-cooled island.