An experimental study of forced convective boiling heat transfer of refrigerants in a rough surface tube

Experiments were carried out on the forced convective boiling heat transfer of refrigerants HCFC22 and HCFC123 inside a tube whose surface was rougher than that of an ordinary smooth copper tube used commercially as heat transfer tube. The local heat transfer coefficients were measured in the range of reduced pressure ratio of 0.07 to 0.23 for mass velocity 300 kg/(m²·s). The measured heat transfer coefficients inside the present tube in annular flow regime are 20-80% higher than those calculated using the authors' previous correlation for an ordinary smooth tube. Once the term representing the nucleate pool boiling heat transfer contribution in this correlation equation is modified by considering the surface roughness effect, the modified equation can correlate the heat transfer coefficients of the present tube within 25% deviations. † Proceedings of the Sixth International Symposium on Transport Phenomena in Thermal Engineering (ISTP-VI), Seoul, Korea, May 9-13, 1993.