Annals of the Assembly for International Heat Transfer Conference 13
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ARTICLE:
Xue-Hu Ma Xing-Dong Zhou Zhong Lan Tian-Yi Song Tao Bai Jia-Bin Chen ABSTRACT To get a better understanding of the mechanism of heat transfer enhancement in dropwise condensation with non-condensable gas, dropwise condensation (DWC), filmwise condensation (FWC) and dropwise-filmwise coexisting (DFC) heat transfer with and without non-condensable gas were all performed on specially designed vertical plates. The investigations were concerned with the dynamic behavior near the vapor-liquid interface. The experimental results indicated that the heat transfer characteristics of dropwise condensation of pure steam without non-condensable gas were similar to that of dropwise-filmwise coexisting condensation surface. However, in the presence of non-condensable gas, without the effect of droplets falling movement in the vapor-liquid interface, the heat transfer characteristics of dropwise-filmwise coexisting condensation surface were parallel to that of filmwise condensation surface, and indeed no heat transfer enhancement was found. Compared with the former two condensation modes, the heat transfer coefficient of dropwise condensation with non-condensable gas was enhanced by 30%∼80% for the air mole concentration of 0.9% and 4.8%, respectively. The facts, which were mainly due to the departure behavior of the condensing droplets, make a considerable contribution to the overall heat and mass transfer performance. HTE-07 pages |
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