PROPERTIES OF NEW REFRIGERANTS AND PREDICTIONS FOR CONDENSATION HEAT-TRANSFER ENHANCEMENT WITH LOW-FINNED TUBES

The present article provides a review of thermophysical properties res earch 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 th eir chemical formulae and quite short atmospheric lifetime may be prom ising 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, sat urated liquid thermal conductivity, and surface tension of these hydro fluorocarbons. For easily available comparisons, the results are prese nted in diagrams illustrating the dependence of thermophysical data on temperature at the saturated state. Heat-transfer predictions are spe cified for condensation of the HFCs on horizontal integral-fin tubes w ith rectangular fins. Parameters investigated include fin and tube geo metry, etc. This study should be a useful input in developing new cond ensers with new refrigerants. Copyright (C) 1996 Elsevier Science Ltd.