Measurement of physical properties of refrigerant mixtures. Determination of phase diagrams (original) (raw)
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Ž. An apparatus for the measurement of vapor-liquid equilibria P-T-x-y data of refrigerant systems was designed, built and tested. The recirculation method was used and the vapor phase was forced through the liquid phase by a magnetic pump. The thermodynamic equilibrium was reached in a visual cell with an internal volume of 50 cm 3. The compositions of the phases were analyzed by a gas chromatograph connected on-line with either FID or TCD detectors. The operating temperature and pressure in the apparatus, as tested before w x delivery to the laboratory R. Stryjek, personal communication , range from 240 to 350 K and from 0.1 to 10 MPa, respectively. The estimated accuracy of the measured data was "0.01 K for temperature, "0.8 kPa for pressure and 0.001 in mole fraction for liquid and vapor compositions. Vapor-liquid equilibria data were Ž .
Calculation of thermodynamic properties and vapor-liquid equilibria of refrigerants
Chemical Engineering Science, 1978
A?Mract-Saturated state thermodynaimc propeNes of ref~rants are prcdrctcd from cnt~cal coordmates and normaI bodmg pomts by usmg Soave's equabon of state Bmary vapor-hquni cqtuhbna are correlated by determmmg mteraction parameters for the followmg SEX systems CC12FJCH3CHF2. CCIJ;JCHCIF~, CHF&X3F3, CClF&Xl~F, CCIZFJCCIS, CFXHS On the whole the method gves rehable results over broad temperature and pressure ranges for pracbcal engmeermg uses IN'WODUCI'ION Temperature Pressure References points range W) range (atm) klz UP (atm) uY CC12FJCH1CHF-Refrtgerant 500
Vapor-Liquid Equilibrium Data Concerning Refrigerant Systems: Equipment, Data and Modelling
Development of modern refrigeration systems is critical for the success of new global environmental protection efforts. The binary system of refrigerants: Hexafluoroethene (R116) + 1,1,1-trifluoroethane (R143a), has been studied with the aim of providing PTxy data. Isothermal vapor-liquid equilibrium data have generated using the "static analytic" method from 258 to 328 K at pressures from 0.39 to 3.89 MPa. The model composed of the Peng-Robinson of state, the Mathias-Copeman alpha function, the Wong-Sandler mixing rules and the NRTL cell theory is applied herein to correlate the data and calculate the critical line.
Refrigeration Science and Technology" proceedings series
2017
In 2014, European F-gas directive plans the prohibition of fluorinated working fluids with GWP of 2500 or more from 2020. Consequently, new working fluids have to be considered in the future such as HydroFluoroOlefin, carbon dioxide or mixture of HFO with hydro-fluoro-carbon or CO 2. The knowledge of the thermo-physical properties of working fluid is essential for the evaluation of performance of heat pumps, ORC and refrigeration. Herein, several "French" laboratories proposed to investigate the thermo-physical properties of the R744 + R1234yf binary system. In 2014, Juntarachat et al. measured and correlated vapour liquid equilibria including mixture critical point. New experimental determinations for density and viscosity using vibrating densitometer and capillary viscometer are presented. Also, enthalpies of mixing are determined using BT-215 Calvet calorimeters. In addition, molecular simulation based on empirical force have been realized. Several thermodynamic and tra...
2002
This project has measured data and developed models for the properties of R410A and other HFC blends. An emphasis was placed on conditions near and above the mixture critical point-conditions where existing data were scarce and where a serious degradation in the performance of airconditioning equipment has been observed. Many of the HFC blends have much lower critical temperatures than the CFCs or HCFCs (primarily R22) they are replacing, meaning that the operating temperatures of equipment using the blends can approach the critical temperature in extreme ambient conditions. In this project the isochoric (constant volume) heat capacity of R125 was measured and a comprehensive, high-accuracy equation of state for the thermodynamic properties of this fluid was developed. R125 is a component of several important HFC blends, and improvements to the pure fluid formulation were a precursor to an improved mixture model. The isochoric heat capacity and pressure-density-temperature (P-ρ-T) behavior of R410A were measured and these data, along with data from the literature, were used to develop a new equation of state applicable to the entire class of HFC blends. Finally, measurements of the viscosity and thermal conductivity of R410A and R507A were carried out and the resulting data were compared to the mixture model in the NIST REFPROP database. R507A is the blend R125/143a (50/50); it is a replacement for R502. The R125/143a binary pair also comprises the majority of R404A, which is the blend R125/143a/134a (44/52/4). In support of the R125 equation of state development, the isochoric heat capacity of R125 was measured over the temperature range 305-397 K (32-124 ˚C) at pressures up to 20 MPa. The measurements overlapped with existing data at lower temperatures and extended well above the R125 critical point of 339 K. These data are presented. A new formulation is presented for the thermodynamic properties of R125 based on both literature data and the new data measured in this project. This equation of state formulation is explicit in the Helmholtz energy and can be used for the calculation of all the thermodynamic properties, including density, heat capacity, speed of sound, enthalpy, entropy, and saturation properties. Ancillary equations are given for the ideal gas heat capacity, the vapor pressure, and for the saturated liquid and vapor densities. To minimize the number of terms, the equation was developed using new non-linear fitting techniques. Comparisons to the experimental data are given to establish the accuracy of properties calculated using the equation of state. The equation of state generally represents the experimental data within their uncertainties. The estimated uncertainties of calculated values are 0.1 % in density, 0.5 % in heat capacity, 0.02 % in speed of sound for the vapor at pressures less than 1 MPa, 0.5 % in the speed of sound elsewhere, and 0.1 % in vapor pressure. Deviations are higher in the critical region. The equation is valid for temperatures from the triple point temperature (172.52 K,-100.63 ˚C) to 500 K (227 ˚C) and pressures up to 60 MPa. Measurements of the P-ρ-T behavior of R410A were completed along 14 isochores (lines of constant density) and covered the temperature range of 200-400 K (-73 to 127 ˚C) with pressures to 35 MPa. The isochoric heat capacity was measured along eight isochores with temperatures ranging from 303 to 397 K (30 to 124 ˚C) with pressures up to 18 MPa. These calorimetric measurements also provided simultaneous data of the P-ρ-T behavior. These data are presented. Mixture models explicit in Helmholtz energy have been developed to calculate the thermodynamic properties of HFC refrigerant mixtures containing R32, R125, R134a, R143a, and/or R152a. The Helmholtz energy of the mixture is the sum of the ideal gas contribution, the compressibility (or real gas) contribution, and the contribution from mixing. The independent
Universal Journal of Mechanical Engineering, 2015
When simulating refrigeration systems or equipment, knowledge of refrigerant thermodynamic properties is required. While some of the refrigerants are made of pure fluids, some of these refrigerants are made by mixing of two or more pure refrigerants with the predetermined percentages. Properties of refrigerants are a major part of international trade, therefore, it is a subject of interest of international standards. In this study a computer model was developed based on Helmholtz equation of state and cubic spline curve fitting models developed by using saturation thermophysical properties of the refrigerants and refrigerant mixtures. Java programming language was used to model equation of state. As an example the equations for R1234yf and R410A were presented in this paper. With the new model, thermodynamic properties of R1234yf and R410A were compared with REFPROP 9.0. It shows that the total mean deviations of the new model are less than 0.5%.
Science and Technology of Environmental Protection, 2002
Vapor-liquid equilibrium, thermodynamic and volumetric properties were predicted for three pure hydrofluorocarbons (R32, R125 and R134a) as well as for binary mixtures of these refrigerants. Three cubic equations of state GEOS3C, SRK (Soave-Redlich-Kwong) and PR (Peng-Robinson) were used. A wide comparison with literature experimental data was made. For the binary refrigerant mixtures, classical van der Waals mixing rules without interaction parameters were used. The GEOS3C equation, with three parameters estimated by matching several points on the saturation curve (vapor pressure and corresponding liquid volumes), compares favorably to other equations in literature, resting simple enough for applications.
Prediction method of both azeotropic and critical points of the binary refrigerant mixtures
2017
The prediction of the azeotropic point and the determination of the critical point in binary mixtures is very important in refrigerating industry. In this task, a simple method is presented in order to predict and determine both azeotropic and critical points. Our method employs experimental data and a thermodynamic model. 1,1,1,2-tetrafluoroethane (R134a) in the mixture presents the possibility of inventing the azeotropic and critical properties. The mixtures studied in this work are: Cyclopropane (RC270), Propylene (R1270), Hexafluoroethane (R116) and Carbon dioxide (R744) based on 1,1,1,2-tetrafluoroethane (R134a). The model consists of the Peng–Robinson equation of state (EoS), the Mathias–Copeman alph a function and the Wong-Sandler mixing rules involving the NRTL model. The results proved that there is a good agreement between the predicted values and the experimental data. The presented methods are able to predict the azeotropic and determine critical positions