Theoretical and experimental analyses of two-phase flow condensation heat transfer inside the horizontal micro-fin tube

•Interaction of the heat transfer mechanism and the flow mechanism for two-phase fluid is clarified under the working conditions.•Prediction effect of the existing correlation on the experimental data was verified.•The dimensionless variable is selected to characterize combined action of various experimental variables on the heat transfer characteristics.•A new correlation with a mean deviation of less than 5% for the heat transfer characteristics is proposed.