Shunroku Sukumoda

Heat Transfer and Pressure Drop During Evaporation and Condensation of HCFC22 in Horizontal Copper Tubes with Many Inner Fins

Heat transfer performance and pressure drop during evaporation and condensation of HCFC22 in horizontal copper tubes with a lot of spiral fins were examined. Each outer diameter of the tubes was 7.00 mm. The number of fins ranged from 55 to 85 and the fin height ranged from 0.21 to 0.24 mm. The mass flux of HCFC22 ranged from 160 to 320 kg/m 2 s. The number of fins that gave the highest heat transfer coefficient was 80 for both evaporation and condensation. The heat transfer coefficient increased with increasing fin height. The pressure drop was not affected so much by the fin height and the number of fins. We discuss the relation between the heat transfer performance and the number of fins in terms of the inner surface area enhancement.