自然通风逆流湿式冷却塔蒸发水损失的数值模拟研究

Three-dimensional Numerical Study on Evaporation Water Losses in a Natural Draft Wet Cooling Tower

以某自然通风湿式冷却塔为研究对象,基于Fluent计算软件建立了包括填料阻力、收水器阻力、填料传热传质等在内的冷却塔三维数值模型,并通过运行数据和经验公式,对所建立的模型进行了验证分析。结果表明,所建立的三维数值计算模型,适合冷却塔流动及传热传质计算。基于所建立的模型对循环冷却塔内的流场特征进行分析,并对蒸发水损失的影响因素进行损失量和温降的计算分析。结果表明,雨滴当量直径减小时,冷却效果增强,出口水温下降,蒸发损失增加;随着循环水量的增加或者进塔水温的升高,蒸发损失增加。因此,减少进塔循环水热量是减少蒸发损失的有效途径。

Taking a natural draft counter-flow wet cooling tower as the research object, a three-dimensional numerical simulation model was established using commercially available software, fluently, with consideration of the influence of resistances from the fill, the water collector and the heat and mass transfer of the fill. Through the operation data and the empirical formula, the established model was verified. The results show that the established 3-D numerical calculation model is suitable for cooling tower flow and heat and mass transfer calculations. The influence factors of flow field characteristics and evaporation water losses was calcu-lated and analyzed, especially the influence on the evaporation water losses and the heat exchange. The re-sults also show that the cooling effect enhances and the outlet temperature drops when the equivalent diame-ter of raindrops reduces. With the increase of circulating water or the rise of inlet water temperature, the evaporation loss increases. Therefore, reducing the tower circulating water heat is an effective way to reduce the evaporation losses.