Comparative analysis of microfin vs smooth tubes in R32 and R410A condensation. (August 2021) - Longo, Giovanni A.
Highlights: This paper investigates R32 and R410A condensation inside a 4.2 mm microfin tube. The microfin tube exhibits a maximum heat transfer enhancement around 3.5−3.6. The optimum mass velocity for the microfin tube is in the range 150−300 kg m −2 s −1 . R32 exhibits heat transfer coefficients and pressure drops higher than R410A. R32 is a very promising low GWP substitute for R410A. Abstract: This study performs the comparative analysis of R32 and R410A condensation inside a 4.2 mm ID microfin tube: the effects of saturation temperature, vapour quality and mass velocities are evaluated. The heat transfer coefficients show a great sensitivity to vapour quality, a non-negligible sensitivity to saturation temperature/pressure, and a non-monotonic trend versus mass velocity. The microfin tube exhibits a maximum heat transfer enhancement with respect to the smooth tube around 3.5−3.6 at a mass velocity of 200 kg m −2 s −1 and a vapour quality of 0.8. The optimum mass velocity for R32 and R410A condensation inside the microfin tube is in the range 150−300 kg m −2 s −1 . R32 exhibits condensation heat transfer coefficients 20 − 30% higher and frictional pressure drops 10 − 20% higher than those of R410A and it seems a valuable low GWP substitute for R410A.