Properties of new refrigerants and predictions for condensation heat transfer enhancement with low-finned tubes

The present article provides a review of thermophysical properties research of environmentally acceptable refrigerants. In recent years, it has become evident that common CFC type refrigerants can cause serious environmental damage when released into the atmosphere. The group of HFCs (HFC-32, HFC-125, HFC-134a, HFC-152a) with no chlorine atom in their chemical formulae and quite short atmospheric lifetime may be promising alternatives to CFCs. A compilation of properties is given which may be used to obtain arithmetic expressions for the vapour pressure, saturated liquid density, viscosity, latent heat of vaporization, saturated liquid thermal conductivity, and surface tension of these hydrofluorocarbons. For easily available comparisons, the results are presented in diagrams illustrating the dependence of thermophysical data on temperature at the saturated state. Heat-transfer predictions are specified for condensation of the HFCs on horizontal integral-fin tubes with rectangular fins. Parameters investigated include fin and tube geometry, etc. This study should be a useful input in developing new condensers with new refrigerants.