填料双层布置对冷却塔进风预冷传热传质过程的影响模拟研究

Effect of medium-gap-medium fill arrangement on heat and mass transfer process of pre-cooling of inlet air of cooling tower:a simulation study

空冷塔的进风预冷可以提升其在高温时段的换热性能,进而提升火电机组的热效率。填料蒸发预冷系统里填料性能直接影响过程的传热传质性能,合理布置填料对提升蒸发预冷过程的冷却性能具有重要意义。针对一种新型填料双层布置形式,采用数值模拟方法研究了该布置下蒸发冷却过程中的传热传质及空气流动性能。研究发现:在风速1.5 m/s、入口空气干球温度27℃、湿球温度19℃的工况下,空气依次经过100 mm填料、100 mm中空、100 mm填料的温降分别为4.3、1.3、1.6℃;所有填料区承担了82.5%的冷却,而中空区域承担了17.5%的冷却。研究为空冷机组冷却塔进风预冷系统的填料优化布置提供指导。

The inlet air pre-cooling can improve the heat transfer performance of dry cooling tower in high temperature periods,and thus enhance thermal efficiency of coal-fired power plants.The wetted medium is the most important element in an evaporative cooling system,and its performance has a direct impact on the heat and mass transfer performance.Reasonable arrangement of wetted medium is of great significance for the performance improvement of the evaporative cooling process.A novel medium-gap-medium arrangement was studied.Numerical simulation methods were used to study the heat and mass transfer and air flow performance in evaporative cooling process with medium-gap-medium arrangement.The results show that,the temperature drop of the air through 100 mm medium,100 mm gap and 100 mm medium are 4.3,1.3 and 1.6℃,respectively,at the air speed of 1.5 m/s,inlet air dry bulb temperature of 27℃,inlet air wet bulb temperature of 19℃.All media section accounts for 82.5%of the cooling,while gap section accounts for 17.5%.The study provides guidance for optimization of layout of wetted medium in the inlet air pre-cooling of dry cooling towers.