| The substitution of new environmentally friendly refrigerants for traditional refrigerants has become one of the research hotspots in the refrigeration and air conditioning industry,and the replacement of mixture is a more practical and efficient research direction.R1234ze(E),belongs to HFOs refrigerant,has excellent environmental protection performance(GWP<1,ODP = 0),but it has the disadvantage of poor thermodynamic performance.R152 a has good thermophysical properties,but its GWP is relatively high.In order to give consideration to environmental protection and good refrigeration performance,it has potential application prospects to compose a new type of mixture.The vaporliquid equilibrium property is one of the most basic thermodynamic properties of mixtures,which is usually obtained by experiment.However,there are few experimental data on the vapor-liquid equilibrium of R1234ze(E)/R152 a.Therefore,this paper will expand the experimental temperature range to conduct experimental research on it.A set of binary mixture R1234ze(E)/R152 a vapor-liquid equilibrium test platform based on liquid phase circulation analysis was established,which mainly included circulation system,liquid phase constant temperature system,measurement system and sampling system.The experimental platform was used to measure the p-T-x-y data of binary mixture.Platinum resistance thermometer PT100 with measuring range of 234.15～333.15 K and accuracy of ±0.01 K was selected to measure the temperature of experimental working fluid.The pressure measuring instrument TERPS8000 with range of 0～7MPa and accuracy of0.01%FS was used.The gas chromatograph with model GC2014 was used to detect the content of each component in the gas phase of the mixture when the vaporliquid phase equilibrium.The uncertainty of system measurement was divided into three parts: the uncertainty of temperature measurement is about 35 m K,the uncertainty of pressure measurement is about 1.5k Pa,and the uncertainty of vaporliquid component is about 0.005.The saturated vapor pressure of R1234ze(E)and R152 a as a single working medium in the temperature range of 298.15K～328.15 K was measured respectively and compared with the query result of REFPROP.The relative errors of saturated vapor pressure for R1234ze(E)and R152 a are-0.22%～0.17% and-0.35%～0.07%,respectively.At the same time,the experimental data of vapor-liquid equilibrium of R1234ze(E)/R152 a in the temperature range of 258.15K～288.15 K were measured and compared with the experimental data in published literatures and the calculated results of PR+vd W model.The results showed that the experimental data and the literature data uniformly fell on the prediction curve of PR+vd W model.It was verified that the measurement accuracy of the experimental device was high,and the PR+vd W model can be used to predict the vapor-liquid equilibrium properties of the mixture.The experiment of vapor-liquid equilibrium at the temperature of298.15 K,308.15 K,318.15 K and 328.15 K was completed with this experimental device,and the data of the molar composition,pressure and temperature of each component were obtained.In order to obtain a more accurate model for predicting the vapor-liquid equilibrium properties of binary mixture R1234ze(E)/R152 a,PR and SRK equations of state were combined with vd W and HV mixing rules to construct four computational models of the mixture: PR+vd W,SRK+vd W,PR+HV and SRK+HV.Comparing the calculated results of the model with the experimental data of vaporliquid equilibrium,it is found that: When the vapor-liquid equilibrium temperature was 298.15 K,308.15 K,318.15 K and 328.15 K,the mean value of the average absolute deviation of vapor-phase mole fraction(AADy)of the four models is 0.003.The mean of the average absolute relative deviation(AARDp)calculated by PR+HV,PR+vd W,SRK+vd W and SRK+HV were 0.25%,0.33%,0.68% and0.61%,respectively.The PR+HV model was more suitable for predicting the vapor-liquid equilibrium properties of binary mixing medium R1234ze(E)/R152 a. |
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