析湿工况下亲水层对波纹翅片管换热器空气侧特性的影响分析

Effect of hydrophilic coating on airside performance of wavy fin-and-tube heat exchangers under dehumidifying conditions

对附带亲水层和没有附带亲水层的波纹翅片管换热器在析湿工况下的空气侧特性进行了实验研究,分析了亲水层对空气侧换热和压降特性的影响。实验表明,当翅片表面凝结出的水滴较少,不能形成水流时,亲水层能够增强空气侧的换热。而当翅片表面凝结出大量的冷凝水并形成水流流动时,亲水层反而减弱空气侧的换热。亲水层对降低空气侧的压降则有显著作用,降低的最大值可达到44%。开发了带亲水层与不带亲水层波纹翅片管换热器析湿工况下空气侧的换热系数比和压降比关联式,平均误差分别为9.9%和8.2%,在±15%误差范围内分别能涵盖76.6%和82.8%实验数据。

The air side heat transfer and friction characteristics of wavy fin-and-tube heat exchangers with and without hydrophilic coating were studied under dehumidifying conditions experimentally. The effects of hydrophilic coating on air side performance were investigated. The results indicated that the hydrophilic coating could enhance heat transfer when condensed water droplets were too few to form water flow on the fin surface but weaken heat transfer when a large amount of condensed water droplets on the fin surface formed water flow. The pressure drop on the hydrophilic coating surface was lower than the corresponding uncoated surface. A maximum 44% reduction was observed. The proposed correlations of heat transfer coefficient and pressure drop for the heat exchanger with and without hydrophilic coating had a mean deviation of 9.9% and 8.2% from experimental data respectively and could cover 76.6% and 82.8% respectively of the experimental data within the deviation limit of ±15%.