环境侧风影响下自然通风空冷塔性能提升研究

针对环境侧风影响下,小型自然通风空冷塔的换热性能提升问题进行数值模拟研究。利用ANSYS/Fluent建立小型间接空冷塔的数值模拟模型,并将数值模拟结果与模型塔在侧风影响下的试验结果进行对比,以验证模型结果的准确性。基于某20m高的小型间接空冷塔的数值模拟结果表明:侧风在塔侧壁外侧引起的“高压区”是形成塔迎风侧散热器底部“负压区”、塔底部侧漩涡的原因,并使塔内空气流量减小。通过安装新型导风装置,将阻止大部分塔侧壁处的侧风往塔进风口处流动,并降低“风盖”的坡度以减小其对塔进风口高度以下侧风方向的影响,使空气通过空冷散热器的面积增大,进而提高塔在侧风影响下的热力特性。相比于未安装导风装置的情况,当侧风从4m/s增大至12m/s,通过安装新型导风装置可使塔的热负荷提升70%~130%。

Research on the Performance Improvement of a Natural Draft Dry Cooling Tower Under Crosswind Conditions

This study is inspired by the CFD research on the improvement of the heat transfer performance of a small natural draft dry cooling tower (NDDCT) under crosswind conditions. The CFD model is build through ANSYS/Fluent and validated against experimental results. The CFD simulation results based on a 20m NDDCT show that the high-pressure zone around the tower side wall, formed by the crosswind, causes the formation of the low-pressure zone beneath heat exchangers on the windward side and the vortex at the bottom of the tower. This would lead to the decrease of air flow through the tower. The new wind guide device prevents the majority of the crosswind around the tower side wall from entering the tower inlet, decreasing the slope of the wind cover to ease its impact on the crosswind's direction and enlarging the heat exchangers' area the air passes through. This significantly improves the tower performance. Compared with the tower performance without the new wind guide device,with the crosswind increasing from 4m/s to 12m/s, the device improves the tower heat load by 70%~ 130%.