Thermodynamic property formulations and heat transfer aspects for replacement refrigerants: R-123 and R-134a
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Stegou-Sagia, A
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This paper reports analytical relations for the thermodynamic properties enthalpy, entropy, heat capacities at constant pressure and temperature of the replacement refrigerants R-123 and R-134a. These refrigerants are considered promising as substitutes for the fluids R-ll and R-12, respectively, which are two of the most widely used CFC refrigerants. In addition to the properties, the three real gas isentropic exponents 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 change equations to describe with good accuracy the real gas behaviour. A systematic study to research the influence of various parameters on heat transfer during condensation of R-123 and R-134a on horizontal integral-fin tubes is also carried out. The results are useful in refrigeration applications to improve the basic design, as a significant concern about new refrigerants to replace the CFCs has increased very rapidly due to the destruction of stratospheric ozone and global warming. (C) 1997 by John Wiley & Sons, Ltd.
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