Condensation heat transfer coefficients of the zeotropic refrigerant mixture R-22/R-142b in smooth horizonal tubes

摘要

Heat transfer coefficients during condensation of the zeotropic refrigerant mixture R-22 with R-142b are presented. Measurements were obtained at different mass fractions in a smooth horizontal tube. All measurements were conducted at a high condensing saturation pressure of 2.43 MPa, which corresponds to a condensation temperature of 60℃ for R-22. The measurements were taken in 8.11 mm inner diameter smooth tubes with lengths of 1603 mm. The heat transfer coefficients were determined with the Log Mean Temperature Difference equations. It was found that at low mass fluxes, between 40 kg·m{sup}(-2)·s{sup}(-1) to 350 kg·m{sup}(-2)·s{sup}(-1), the refrigerant mass fraction influences the heat transfer coefficient by up to a factor of two. The heat transfer coefficients decrease as the fraction of R-142b is increased. At high mass fluxes, of 350 kg·m{sup}(-2)·s{sup}(-1) and more the heat transfer coefficients were not strongly influenced by the refrigerant mass fraction. The average heat transfer coefficient decreased by only 7% as the refrigerant mass fraction changed from 100% R-22 to 50%/50% R-22/R142b.