Abstract
Nucleate pool boiling heat transfer coefficients (HTCs) of 14 refrigerants are measured from a 19mm o.d. plain copper tube heated by a cartridge heater. All measurements are carried out in the pool temperature of 4∼25°C and in the heat flux of 10∼80kW/m2. Test results show that HTCs of R32, R125, R143a, R152a, and R410A are higher than those of R22. Especially, R32 showed the highest HTCs among all the refrigerants tested. As for R22 alternatives, HTCs of R410A are 50% higher than those of R22 while those of R407C are very similar to those of R22. It is also found that some of the popular pool boiling heat transfer correlations in the literature failed to predict the HTCs of newly developed alternative refrigerants. Hence, a dimensionless analysis is carried out in an attempt to develop a general correlation for all HTCs of pure refrigerants. Thus developed correlation showed an excellent agreement with all experimental data showing a mean deviation of 5.5%.
