雨区干湿混合模式对超大型湿式冷却塔传热传质性能影响的数值模拟

Numerical Simulation on the Effect of Dry-wet Hybrid Cooling in Rain Zone on Heat and Mass Transfer Performance for the Super-large Wet Cooling Towers

为解决超大型湿式冷却塔雨区进风阻力大、传热传质性能沿径向分布不均等问题,提出雨区干湿混合的冷却模式。建立超大型湿式冷却塔三维数值计算模型,并进行验证。定义半径占比g、安装角a等参数,并设计不同半径占比g、收水板宽度d和安装角a的多种优化方案,研究不同优化方案下冷却塔内的空气动力场及传热传质性能。结果表明,雨区干湿混合模式可减小雨区进风阻力,提高塔内空气动力场均匀性;当y=2/3、α=15°及d=16.50m时,冷却塔传热传质性能相对优化值:与原始常规塔相比,水温降增大了0.24℃,冷却数提高了0.12,通风量提升了1690kg/s。另外,全塔抽力随干区面积增大而升高,干湿混合冷却模式可使全塔抽力提高10.6Pa。

To solve the problems of large resistance to airflow,non-uniform distribution of heat and mass transfer performance along radial direction in the rain zone of the super-large wet cooling tower,the water collecting modules were arranged in the rain zone to realize the dry-wet hybrid cooling mode.A three-dimensional numerical computation model of super-large wet cooling tower was established,and was validated.In this paper,the ratio of receiving plate length l to the rain zone radius r was defined as radius ratio g,the angle between receiving plate and horizontal plane was defined as installation angle a.A variety of optimization schemes were designed for the combination of different radius ratio g,width of receiving plate d and installation angle a,the aerodynamic field distribution and the heat and mass transfer performance under different schemes were studied.The results show that the wet-dry hybrid mode in rain zone reduces the resistance to airflow and improves the uniformity of aerodynamic field.The heat and mass transfer performance are relatively optimal under y=2/3,α=15°and d(28)16.5 m model,compared with conventional tower,the water temperature drop enhances by 0.24℃,the Merkel number rises by 0.12,and the ventilation rate increases by 1690 kg/s.Meanwhile,the tower airflow pressure difference increases by 10.6 Pa with the expansion of dry area.