Abstract The cooling performance of natural draft dry cooling towers (NDDCTs) would significantly be reduced when the ambient air is hot. To address this problem, the spray pre-cooling technology has been introduced to cool the inlet air of the tower. The effect of two-nozzle distance on the evaporative cooling performance will instruct the arrangement of multi-nozzle for industrial applications. This paper is therefore to study two nozzles vertically arranged in a wind tunnel by the numerical simulation. A 3-D model was developed and validated for simulation studies. The effects of two-nozzle distance, inlet air speed, inlet air dry-bulb temperature and humidity on the evaporative cooling performance were investigated. Besides, a modified cooling efficiency was proposed to effectively evaluate the cooling performance with considering both the cooling affected region and the air temperature drop. The simulation results indicate that the modified cooling efficiency is more or less affected by the two cooling affected regions generated by two nozzles at the wind tunnel exit. The modified cooling efficiency of the tangent region is similar to that of the separating region, and it is 2.5% higher than the partially overlapping region. Generally, the high modified cooling efficiency is accompanied with the high air dry-bulb temperature and the low humidity. The modified cooling efficiency increases with the decreasing inlet air speed.

中文翻译：

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不同工况下双喷嘴喷雾冷却系统性能的数值研究

摘要 当环境空气较热时，自然通风干式冷却塔（NDDCT）的冷却性能会显着降低。为了解决这个问题，引入了喷雾预冷技术来冷却塔的入口空气。两喷嘴距离对蒸发冷却性能的影响将指导工业应用中多喷嘴的布置。因此，本文旨在通过数值模拟研究风洞中垂直排列的两个喷嘴。为仿真研究开发并验证了 3-D 模型。研究了两喷嘴距离、进风速度、进风干球温度和湿度对蒸发冷却性能的影响。除了，提出了一种改进的冷却效率，以在考虑冷却影响区域和空气温度下降的情况下有效地评估冷却性能。仿真结果表明，修正后的冷却效率或多或少受到风洞出口处两个喷嘴产生的两个冷却影响区的影响。切线区域的修正冷却效率与分离区域相似，比部分重叠区域高2.5%。通常，高改进冷却效率伴随着高空气干球温度和低湿度。改进的冷却效率随着入口空气速度的降低而增加。仿真结果表明，修正后的冷却效率或多或少受到风洞出口处两个喷嘴产生的两个冷却影响区的影响。切线区域的修正冷却效率与分离区域相似，比部分重叠区域高2.5%。通常，高改进冷却效率伴随着高空气干球温度和低湿度。改进的冷却效率随着入口空气速度的降低而增加。仿真结果表明，修正后的冷却效率或多或少受到风洞出口处两个喷嘴产生的两个冷却影响区的影响。切线区域的修正冷却效率与分离区域相似，比部分重叠区域高2.5%。通常，高改进冷却效率伴随着高空气干球温度和低湿度。改进的冷却效率随着入口空气速度的降低而增加。高改进冷却效率伴随着高空气干球温度和低湿度。改进的冷却效率随着入口空气速度的降低而增加。高改进冷却效率伴随着高空气干球温度和低湿度。改进的冷却效率随着入口空气速度的降低而增加。