喷水预冷特性对蒸发冷却性能影响的数值模拟

Numerical Simulation of the Influence of Water Spray Precooling Characteristics on Evaporative Cooling Performance

为改善间接空冷塔在夏季高温环境下的冷却性能,提高火电厂整体效率,基于计算流体力学建立了空冷单元喷水预冷系统的数学模型,分析了喷水预冷特性对空冷塔某一扇区的影响,分别计算了环境特性和喷嘴特征等因素对冷却效率、有效冷却区域的温降和面积的影响。结果表明:随着流动距离的增加,冷却效率逐渐提高;环境风速和空气相对湿度降低以及风温、张角、喷嘴质量流量和喷嘴间距增大均会使冷却效率提高;液滴随空气流动逐渐蒸发,有效冷却区域的面积沿流动方向逐渐增大;有效温降沿着流动方向先因液滴的蒸发而增加,而后因冷却空气与周围空气的传热传质而减小。

In order to improve the cooling performance of indirect air cooling tower in high temperature environment of summer,so as to improve the overall efficiency of thermal power plant,the numerical model of water spray precooling system of air cooling unit was established based on computational fluid dynamics.The influence of water spray precooling characteristics on a certain sector of air cooling tower was analyzed,and the effects of environmental characteristics and nozzle characteristics on cooling efficiency,temperature drop and area of effective cooling area were calculated,respectively.Results show that the cooling efficiency increases with the increase of flow distance.The cooling efficiency can be improved when the ambient wind speed and air humidity decrease,the wind temperature,the opening angle,the mass flow and spacing of the nozzle increase.The droplets gradually evaporate with the flow of air,and the area of the effective cooling area gradually increases along the flow direction.The effective temperature drop first increases along the flow direction due to the evaporation of droplets,and then decreases due to the heat and mass transfer between the cooled air and the surrounding air.