A numerical investigation of convective condensation in micro-fin tubes of different geometries

A numerical investigation was conducted to determine the effects of fin shape on heat transfer coefficients during in-tube condensation of R410A. Four micro-fin tubes of different geometries were selected for this study, including a straight-finned one and three helical tubes, and two different helical angles of 18 degrees and 31 degrees were included to explore the influence of helical angles. The numerical results were verified by previous experimental results. It was found that there was a positive relationship between heat transfer coefficients and mass velocities and vapor quality, while the helical angle seemed to improve the heat transfer coefficients especially for medium vapor quality. A nearly symmetrical liquid film distribution was found along the circumference for all three micro-fin tubes due to the centrifugal force, while the liquid tends to accumulate at the bottom of the straight-finned tube.