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Annals of the Assembly for International Heat Transfer Conference 13

ISBN 1-56700-225-0 / CD 1-56700-226-9

Volumes per year:

various

Year 2006

DOI: 10.1615/IHTC13.p17

CONDENSATION HEAT TRANSFER ENHANCEMENT FOR STEAM-AIR MIXTURE VAPOUR BY INTERFACIAL BEHAVIOR OF THE FALLING DROPLETS

Xue-Hu Ma
Institute of Chemical Engineering, Dalian University of Technology, Dalian 116012 China

Xing-Dong Zhou
Institute of Chemical Engineering, Dalian University of Technology, Dalian 116012 China

Zhong Lan
Institute of Chemical Engineering, Dalian University of Technology, Dalian 116012 China

Tian-Yi Song
Institute of Chemical Engineering, Dalian University of Technology, Dalian 116012 China

Tao Bai
Institute of Chemical Engineering, Dalian University of Technology, Dalian 116012, China

Jia-Bin Chen
Institute of Chemical Engineering, Dalian University of Technology, Dalian 116012, China

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.