Thermodynamic Properties Of Multicomponent Mixtures And Study On The Environmental Friendly Refrigerants

It can be seen from the F-gas regulation proposed by EU in 2006 and the revise(NO.517/2014)of F-gas regulation made by EU in 2014 that humans are paying more attention to controlling the GWP of refrigerant.Because china is the largest HCFCs producer and consumer in the world,furthermore,the GWP of the traditional alternative refrigerants for HCFCs are higher,such as R134 a,R410A,R407 C and so on.Seeking environmental-friendly alternative refrigerants has been one of the important tasks to realize the sustainable development strategy in the refrigeration and air conditioning field of our country.Theoretical study on the substitute of the mixing working fluids has been made in the case of R134 a which has been usually used in vehicle air conditioner currently in this paper.The thermodynamic properties of R134 a,R1234yf,R1234ze(E),R32,R152 a,R600a and their mixtures have been analyzed.According to the thermodynamic differential equations,the thermodynamic properties of each pure working fluid are acquired by combining CSD or MH EOS with saturated liquid density equation,saturated vapor pressure equation and ideal gas specific heat equation.To analyze the vehicle air-conditioning refrigeration cycle performance of each pure working fluid conveniently,based on the compiled thermodynamic property calculation program,the theoretical cycle calculation platform is developed by VS2010.The checking computation and comparison shows that the calculation accuracy of platform is higher and meets the need of engineering calculation.Based on the platform,the cycle performance differences of each working fluid are compared with R134 a respectively.By comparison,it is shown that R1234 yf contributes to realizing perfusion substitution directly and the possible proportioning schemes of working fluids are acquired.The thermophysical properties models of mixing working fluids are developed by combining RKS,PR,MH-81 EOS with several mixing rules.The vapor-liquid equilibrium properties of mixtures are analyzed by the models developed by PR+vdW which is selected according to the calculation precision and stability after comparing the VLE calculation results of the models of each binary mixture.It is found that R1234yf/R134 a,R1234yf/R600 a,R1234ze(E)/R600 a,R1234yf/R134a/R152 a and R1234yf/R134a/R600 a are azeotropic mixtures,R1234yf/R152 a and R1234ze(E)/R152 a are near-azeotropic mixtures,R1234yf/R32 is zeotropic mixture.Then the thermodynamic properties of mixing working fluids arecalculated by combining which with residual function method.To acquire the theoretical cycle performance of the mixing working fluids,the refrigeration cycle calculation programs for mixing working fluids are compiled based on the cycle calculation programs for pure working fluids.The appropriate mole fraction ratio range is identified by setting filter conditions for the bubble or dew pressure,cycle performance under typical operating conditions of vehicle air-conditioning of mixing working fluids with different mole composition ratios.Then,the cycle performance of mixing working fluids of which the mole composition ratios are in the appropriate range is compared with R134 a and R1234 yf.It is shown that the potential of R1234yf/R134a(0.89/0.11),R1234yf/R152a(0.80/0.20),R1234yf/R134a/R152a(0.71/0.12/0.17),R1234yf/R134a/R600a(0.74/0.21/0.05)to replace R134 a directly is higher and the COP of it is higher than R1234 yf.Finally,the optimization methods for improving the performance of refrigeration system with alternative working fluids are pointed by comparing the relationships between the performance of refrigerating systems for mixing working fluids and degree of undercooling,superheat and condensing temperature.