THERMODYNAMIC PROPERTY FORMULATIONS AND HEAT-TRANSFER ASPECTS FOR REPLACEMENT REFRIGERANTS - R-123 AND R-134A

This paper reports analytical relations for the thermodynamic properti es enthalpy, entropy, heat capacities at constant pressure and tempera ture of the replacement refrigerants R-123 and R-134a. These refrigera nts are considered promising as substitutes for the fluids R-ll and R- 12, respectively, which are two of the most widely used CFC refrigeran ts. In addition to the properties, the three real gas isentropic expon ents k(p,v),k(v,T),k(p,T) are calculated, which may be used instead of the classical exponent k = c(p)/c(v), in the ideal gas isentropic cha nge equations to describe with good accuracy the real gas behaviour. A systematic study to research the influence of various parameters on h eat transfer during condensation of R-123 and R-134a on horizontal int egral-fin tubes is also carried out. The results are useful in refrige ration applications to improve the basic design, as a significant conc ern about new refrigerants to replace the CFCs has increased very rapi dly due to the destruction of stratospheric ozone and global warming. (C) 1997 by John Wiley & Sons, Ltd.