串联型复合式冷却塔数学模型及试验验证

摘要

A mathematic modeling of the tandem-type hybrid cooling tower(THCT) that combines a dry region and a wet one is given.The simulation is completed using Matlab and a bench is set up for test.The results indicate that the temperature drop of the cooling water increases with the wind velocity,while the air outlet temperature is almost unchanged and the air outlet enthalpy decrease.Besides,the spray water can markedly influence the temperature drop of cooling water but has less effect on the temperature and enthalpy of the outlet air.Comparison shows that the maximum relative deviation between the calculated and tested values does not exceed 12％,thus the model is accurate enough for engineering usage.The parameters changing under different heights of THCT are calculated and analyzed using the mathematical model when the flow rate of spray water is 2.1 m3/h and the wind velocity is 3.0 m/s.The results indicate that the air enthalpy increases with the height of THCT,the air temperature is almost unchanged in the evaporative cooling section while has a significant increase in the finned tubes.The temperature drop of cooling water in the finned tubes accounts for about 36 ％ in all temperature reduction.The spray water meets a temperature decrease through the fills but heats up and then cools down in the evaporative cooling section.%构造串联型干湿结合复合式冷却塔的数学模型,利用Matlab软件进行模拟计算,搭建试验台进行试验研究.结果显示:随着截面风速增加,冷却水进出口温差逐渐增大,而出口空气温度基本不变,焓值减小,喷淋水量对冷却水进出口温差有显著影响,但对出口空气温度和焓值影响较小.模拟计算结果与试验测试值的最大相对误差不超过12％,说明该数学模型精度满足工程计算要求.利用该数学模型计算并分析了喷淋水量为2.1 m3/h和截面风速为3.0 m/s时各参数随冷却塔高度的分布情况,结果显示:空气焓值随冷却塔高度增加而增加;空气温度在蒸发冷却段基本不变而在翅片管段显著增加,冷却水在翅片管段温降占总温降的36％左右;喷淋水流经填料层后温度降低,而在光管蒸发冷却段呈现先升温后降温现象.