发电厂直接空冷系统空冷岛热态流场特性分析

Experimental Investigation on Thermal Flow Field Characteristics of a Direct Air-cooled System for a Large Power Plant

首次在低速风洞中对直接空冷系统模型进行了PIV流动显示实验,并测量了相应工况下空冷岛底部平均回流率的大小,探讨空冷岛热态流场特性与空冷岛底部回流率之间的关系,研究结果发现:空冷岛的热态流场结构对空冷岛底部平均回流率影响很大;随着来流风速的增加,空冷岛背风面漩涡结构的紊动卷吸和混合作用增强,使得空冷岛底部平均回流率增加.增加挡风墙高度以及在空冷平台外围安装水平前向挡板,能够改善空冷岛的热态流场结构,降低空冷岛下平均回流率,从而改善空冷散热器的散热效果.

The PIV experiments were carried out on thermal flow field of a direct air-cooled system in the low speed wind tunnel for the first time. At the same time, the recirculation ratio at cooling tower of corresponding conditions was measured. After that the relationship between the thermal flow field structure and recirculation ratio under the cooling tower was discussed. The experimental results show that the thermal flow field structure has great effects on the average recirculation ratio under the cooling tower. As increasing with the coming wind velocity, the turbulent entrainment and mixing-up of vortex structure in the lee of cooling tower enhance as well, which causes recirculation ratio under cooling tower increase. Lengthening the height of wind wall or installing the frontal board to the platform can both ameliorate the thermal flow field structure of cooling tower, and the recirculation ratio under cooling tower can be decreased, so the effect of heat dispersion for air-cooled condenser can be improved.