Abstract
Experiments were performed to study the flow characteristics and heat transfer during condensation of non-azeotropic refrigerant blends (NARBs) of R114 and R113 in the annulus of a horizontal double tube. The inner tube was a 19.1mm o.d. corrugated tube with soldered wire fins on the outer surface. The outer tube was a 29.9mm i.d. smooth tube. Experiments were performed at two vapor mass fractions of R114 at the test section inlet of 0.23 and 0.36. The mass velocity of the test fluids ranged from 50 to 200kg/m2·s. The frictional pressure gradient data were correlated fairly well by an empirical equation for condensation of pure R11 and R113 reported in a previous paper. The double tube showed a significant heat transfer enhancement over a smooth tube value. The heat transfer coefficient for NARBs was considerably smaller than that for pure R113. The decrease was more significant for a low mass velocity. A dimensionless correlation for the vapor phase mass transfer coefficient was derived, where the dimensionless parameters for forced convection condensation from a vapor-gas mixture flowing normal to a cylinder was extended to the case of NARBs.
