功能表面降膜蒸发传热特性的实验研究

Preliminary investigation of seawater falling film evaporation on treated functional surfaces

研究了处理表面镀铬铝管、PTFE铜管和纯铝氧化管水平管降膜蒸发传热 ,研究了喷淋密度、热流密度、管内蒸汽速度和管表面处理对降膜蒸发传热特性的影响。实验结果表明 :在表面蒸发区 ,水平管降膜蒸发传热系数随热流密度的增加而提高 ,随喷淋密度增大先降低后升高 ,冷凝侧传热系数基本保持不变。总传热系数对操作条件变化很不明显 ,表面阳极氧化膜使传热系数略有下降 ,但由于其优良的抗垢耐蚀性能 ,非常有必要再进行深入地研究。

Falling film evaporation heat transfer characteristics water were investigated on the external surface of ion-plated chromium, anodized aluminum tubes and PTFE coated brass tubes, which were horizontally oriented in the evaporating chamber. The influences of water irrigation density, heat flux, steam velocity inside tubes and various functional coatings on heat transfer characteristics were also studied. Experimental results indicated that the heat transfer coefficient of falling film evaporation increased with the heat flux increasing in the surface evaporation zone, and increased at first and then decreased with the water irrigation density increasing. However, the heat transfer coefficient on condensation side was almost constant. The effect of operating factors on overall heat transfer coefficient was unconspicuous. Anodized surface film slightly deteriorated the heat transfer due to its lower thermal conductivity, however, its good anti-fouling and anti-corrosion feature shows a potential application in seawater desalination system, and it is necessary to carry out further study in the future.