Experimental study on CO2 flow condensation in a smooth horizontal tube at low temperatures

Abstract

An experimental study was conducted to measure the flow condensation rate of CO2 in a smooth horizontal copper tube with an inner diameter of 4.73mm at saturation temperatures of -10, -5 and 0˚C. The mass fluxes tested ranged from 100 to 500kg/m2-s with a wide range of vapour qualities. The local flow regimes of the measurement data points in this study were predicted by the CO2 condensation flow regime transition criteria proposed by the current authors. Heat transfer characteristics of the experimental results were summarised as the effects of the working conditions on the flow condensation rate in the different flow regimes. Experimental data showed that effects of mass flux and vapour quality on the rate of heat transfer were more significant for annular flows than for stratified flows, and that high mass fluxes and vapour qualities resulted in high heat transfer rates. Experimental data also showed that decreasing the saturation temperature significantly increased the heat transfer rate in annular flows compared to flow condensation in stratified flows.