湿工况下平直翅片对流传热传质数值研究

NUMERICAL STUDY ON CONVECTIVE HEAT AND MASS TRANSFER OF PLAIN FIN IN WET CONDITIONS

建立了湿空气流经平直翅片通道并伴有凝结现象发生的三维对流传热传质的数值模型,在空气进口雷诺数Re为190～3770,进口相对湿度φ_(in)为50%～90%的范围内,对干湿两种工况,平直翅片通道内的换热流动进行了对比研究。结果表明:湿工况换热系数为干工况换热系数的2.8～3.1倍,干工况翅片效率比湿工况翅片效率高35.8%～41.9%。当翅片为部分湿工况时,翅片效率随进口相对湿度的增大而增大,换热系数随进口相对湿度的增大而减小;当翅片为全湿工况后,进口相对湿度对翅片效率和换热系数的影响微弱。

A 3D numerical model of convective heat and mass transfer is presented for plain fin in wet conditions.The heat and mass transfer characteristics of plain fin under dry and wet conditions are compared with the Reynolds number ranging from 190 to 3770 and the air inlet relative humidity ranging from 50%to 90%.Results show that heat transfer coefficient under wet conditions is 2.8～3.1 times higher than that under dry conditions,and the dry fin efficiency is about 35.8～41.9 percent higher than the corresponding wet fin efficiency When the plain fin is in the partially wet conditions,the wet fin efficiency increases with increase of inlet relative humidity,whereas the heat transfer coefficient decreases with increase of inlet relative humidity.When the plain fin is in the fully wet conditions, the effects of inlet relative humidity on the wet fin efficiency and heat transfer coefficient are very small.