Experimental analysis of R410A flow in helically rib-roughened tubes

In this study, an experimental setup was built to investigate the two-phase flow characteristics of R410A refrigerant fluid inside a horizontal internally micro-fin helical coiled tube made of copper. The experimental measurements are carried out with a fixed refrigerant fluid evaporation with temperature equals to 10 degrees C for eleven mass fluxes values varied from 0.00635 (kg/s) to 0.02150 (kg/s), and the Reynolds number ranged from 6998 to 23,695 covering turbulent flow regime. The heat flux supplied to the micro finned test section was fixed in 10 (kW/m(2)) and mixture quality at 30% of the vapor phase. The experimental results were accurately measured under the diabatic condition. Friction factor and heat transfer coefficient were obtained experimentally and compared with available literature correlations for smooth and finned tube configurations. Results showed that the presence of internal helical-rib roughness increased friction factor by 27% when compared with a smooth wall, and 5.3% when compared with finned tubes correlation. New correlation to predict the friction factor of R410A refrigerant fluid inside the micro-fin helical coiled tube was developed based on flow patterns and it agrees with experiment data within the deviation of +/- 0.4%. The heat transfer coefficient shows a minimum average deviation of 10.5% when compared with literature.