Some modelling of cooling cycles used in individual and mixed refrigerants

The study deals with the application of the Carnahan–Starling–De Santis (CSD) equation of state (EOS) to hydrocarbon and haloginated hydrocarbon substances and their mixtures that can be used as alternative refrigerants. The substances studied are the ozone layer friendly liquids (HFC134a, HFC152a, HC600a a.o. and their mixtures). Experimental thermodynamic data of the individual substances and some mixtures were selected for a statistical treatment. thms were produced to adopt experimental data to CSD EOS. They permit to evaluate coefficients of EOS using experimental data. Another group of routines was produced for the purpose of calculating thermodynamic properties of cooling liquids and blends. Software programs were combined in a data base with the next functions: to evaluate coefficients of CSD EOS, to calculate thermodynamic properties and to determine characteristics of refrigerating cycles (compressor power Ncomp, evaporator capacity Q a.o.). Ss were elaborated for HFC134a, HC600a a.o. and mixtures (azeotrope, quaziazeotrope and zeotrope systems). A calculation and a comparison of cycle characteristics were undertaken to determine changes (increasing or decreasing) that should be expected in Ncomp, Q and COP=Q/Ncomp when a new refrigerant substitutes CFC12. This modelling of several type of cooling cycles was done for the mentioned pure substances and mixtures: (1) zeotrope blends HC290/HC600a, MP39 and SM1C; (2) quaziazeotrope mixtures HFC134a/HFC152a; (3) zeotrope systems HFC134a/HFC152a and HC600a/HFC152a. The modelling showed that the blends HFC134a/HFC152a and HC600a/HFC152a have some advantages relative to others.