Investigation on condensation heat transfer and pressure drop of R410A during upward flow in vertical smooth and micro-fin tube

Heat transfer and pressure drop performance of refrigerant R410A condensation during vapor flowing upward in a smooth tube with inner diameter of 8.32 mm and a micro-fin tube with fin root diameter of 8.76 mm are experimentally investigated. The test section is a 0.5 m long double tube with refrigerant flowing in the inner tube and cooling water flowing in the annulus in the same direction. Experiments are conducted at saturation temperatures 40 °C, 45 °C and 48 °C with mass fluxes in the range of 80-345 kg/m2 s. Four different cooling water flow conditions in the test section are set up to compare the heat transfer enhancement factors and pressure drop penalty factors of the smooth tube and micro-fin tube. The total pressure drops across the test section are directly measured by a differential pressure transducer. The experimental data are compared with some well-known heat transfer correlations of micro-fin tube. The correlation suggested by Chamra and Mago shows the best agreement with the present data and exhibits an average deviation of 31.08 and a mean deviation of 35.74. Based on the experimental data, two revised correlations for condensation heat transfer and the frictional pressure drop in micro-fin tube are proposed, within ±15% and ±25% deviation band respectively.