The annular thin film condensation of vapors of wet flue gas in vertical tubes was studied theoretically and experimentally. The convection heat transfer is increased by the condensation of the condensable gas (water vapor) existing in the wet flue gas. This paper discusses the effects of the condensation of a small amount of water vapor (10%-20% fraction) on convection heat transfer in a vertical tube. The flows (Re=2300 - 5000) in vertical tube were investigated experimentally. Some interesting results were obtained. The wall temperature was an important factor affecting the condensing rate and the fog formation in the wet flue gas. The proportion of the sensible and latent changes with the Re number. The fog formation in the wet flue gas influences on the condensing rate and has a significant effect on heat transfer. When the wall temperature is much lower than the saturate temperature of the inlet wet flue gas, the effect of superheat can be neglected. But when fog forms in the bulk flow, the temperature and concentration profile is changed. In the concentration range researched the effect of water vapor condensation heat transfer is discussed, but the convection heat transfer of mixture gas can not be neglected. A modified film model was used to predict the performance of the mixture gas. The comparison of the experiment results with the predictions shows reasonably good agreement.
展开▼
