Experiment and simulation on downward flow condensation of nitrogen in vertical tubes

Abstract

The heat transfer characteristics of nitrogen downward flow condensation are measured in 2 mm and 1 mm vertical tubes. The saturation temperature of nitrogen ranges from 100.4 to 108.0 K. The mass flux varies from 32.7 to 78.6 kg/m2 s for 2 mm tube and from 52.4 to 314.4 kg/m2 s for 1 mm tube. Experimental results of the flow condensation heat transfer coefficient are proposed and analyzed for different vapor qualities, mass fluxes, tube diameters and saturation temperatures. An annular condensation model with the consideration of the interfacial shear stress and the gravity is proposed based on the assumption of uniform film thickness around the tube’s circumference, and the model is validated by the experimental data. Based on the model, the flow and heat transfer characteristics, including the thickness of the liquid film and the condensation heat transfer coefficient are analyzed. Finally, the model and several previous correlations of flow condensation heat transfer coefficient are evaluated by the comparison with the experimental data.