Absolute Relative Deviation Of Pressure Research Articles

Vapor-liquid equilibrium measurement for carbon dioxide (CO2)+propylene (R1270) binary mixture at temperatures from subcritical to supercritical

CO2-based binary mixtures have good performance and environmental friendliness, which are considered a good choice for working fluid in cooling and power cycles. Analyzing the properties of the vapor-liquid equilibrium is used to calculate the enthalpy and entropy of the dew and bubble point, which are fundamental parameters of thermodynamics. In this study, we measure the vapor-liquid equilibrium experimental data of CO2-propylene mixture by static thermostatic analysis experimental system. The working fluids in this state are repeatedly collected from the equilibrium cell to the gas chromatograph by the two electromagnetic capillary samplers to analyze the molar fractions. The maximum pressure deviation and maximum relative pressure deviation of the saturation vapor pressure of propylene are -0.004 MPa and -0.38%, respectively. We measure 5 sets of isotherms from 283.73 to 323.72 K, two of which are supercritical temperatures (313.73 K and 323.72 K). The pressure is up to about 6.4 MPa. The standard experimental uncertainties of mole fractions, pressure, and temperature are within 0.004, 0.002 MPa, and 0.06 K, respectively. The association model (the Peng-Robinso equation incorporating the Wong-Sandler mixing rule and the Non-Random Two-Liquid model) is used to fit the obtained vapor-liquid equilibrium data. The value of the average absolute relative deviation of pressure (AARDp) and the average absolute deviation of vapor phase molar fractions of component 1 (AADy1) is 0.29 % and 0.0062, respectively. The relative volatility under the five isotherms is also calculated, and most of the experimental data were within ± 5 % deviation.

Vapor-liquid equilibrium measurements and models for the ternary mixtures of R1234yf + R32 + R125 and R1234yf + R32 + CO2

R1234yf as the environmental friendly refrigerant has a low volumetric refrigeration capacity and light flammability. The refrigerant mixtures are expected to achieve excellent thermophysical performance, safety and environmental performance. The vapor-liquid equilibrium (VLE) is one of the most important properties of the mixtures. In this work, the VLE property of R1234yf + R32 + R125 and R1234yf + R32 + CO2 ternary mixtures were measured along 5 isotherms from 273.15 K to 313.15 K by a recirculation analytical apparatus. The Peng-Robinson (PR) equation of state combined with the van der Waals (vdW) mixing rule (PR + vdW), as well as the PR equation of state combined with the Wong-Sandler (WS) mixing rule and the non-random two-liquid (NRTL) activity coefficient model (PR + WS + NRTL) were used to correlate the VLE data. The model parameters were temperature-dependent and could describe the VLE properties of the ternary and binary subsystems. The results showed that the PR + WS + NRTL model was better than the PR + vdW model. The average absolute relative deviation of pressure (AARD(p)) and average absolute deviation of compositions (AAD(y)) of the PR + WS + NRTL model were 0.4% and 0.003 for R1234yf + R32 + R125 ternary mixture, and were 0.7% and 0.007 for R1234yf + R32 + CO2 ternary mixture. Experimental results and model calculations showed that both the ternary mixtures were zeotropic.

Isothermal Vapor–Liquid Equilibrium for the Tetrafluoromethane (R14) + Octafluoropropane (R218) Binary Mixture at Five Temperatures from 173.150 to 213.150 K

Tetrafluoromethane (R14) and octafluoropropane (R218) are essential nonflammable refrigerants for mixed-refrigerant Joule Thomson refrigerators. In this paper, the vapor–liquid equilibrium (VLE) data were acquired for the R14 + R218 binary mixture from 173.150 to 213.150 K by a vapor-phase single-cycle method. The VLE data were regressed by the Soave–Redlich–Kwong (SRK) equation of state plus van der Waals (vdW) mixing rule model (SRK-vdW) and the Soave–Redlich–Kwong (SRK) equation of state combined with modified Huron–Vidal first-order (MHV1) mixing rule plus non-random two liquids (NRTL) activity coefficient model (SRK-MHV1-NRTL). The maximum average absolute relative deviation of pressure (AARDp) and the maximum average absolute deviation of vapor-phase mole concentration (AADy) are 2.42% and 0.0019 for the SRK-vdW model, respectively. A better correlation result was obtained by the SRK-MHV1-NRTL model, and the maximum AARDp and AADy are 1.04% and 0.0019, respectively. Based on the experimental and calculated results, a strong non-azeotropic behavior was found.

Experimental investigation on vapor-liquid equilibrium for 1,1-difluoroethane(R152a) +trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) binary systems

At present, environmental impact is considered as primary index in refrigerant selection. R1234ze(E) is an environmentally friendly alternative to R22, but it has drawbacks of poor cycling performance and low refrigerating capacity. R152a has certain flammability though having excellent thermodynamic properties. Therefore, based on their complementary advantages, R1234ze(E) is blended with R152a to be a new mixture. Vapor-liquid equilibrium (VLE) data is the basis of calculating the thermodynamic properties of mixtures. This paper presented the experimental data on the vapor-liquid equilibrium of the binary mixture R152a/R1234ze(E) measured up to 328.15 K for the first time, which was measured by the liquid-phase cycling method. The Peng-Robinson (PR) equation of state (EOS) in conjunction with van der Waals (vdW) mixing rule was used to construct a computational model to correlate the experimental data. The model exhibited a high degree of agreement with the experimental result for binary mixture R152a/R1234ze(E). The maximum average absolute relative deviation of pressure (AARDp) and the average absolute deviation of vapor-phase mole fraction (AADy) for the model were 0.34% and 0.003, respectively.

Binary mixture isothermal vapour-liquid equilibrium: Trifluoromethane (R23) + octafluoropropane (R218) at the temperature from 223.150 K to 263.150 K

The mixed-refrigerant Joule-Thomson refrigerator (MJTR) is simple in structure, safe and reliable, and is suitable for temperatures from 80 to 230 K. Trifluoromethane (R23) and octafluoropropane (R218) are satisfactory as non-flammable refrigerants in MJTR. In this paper, the gas-phase single-cycle method was used to conduct a vapor–liquid equilibrium (VLE) experiment on the R23 + R218 binary system in the temperature range from 223.150 K to 263.150 K. The VLE experimental data were correlated using the Peng-Robinson (PR) equation of state and the Huron-Vidal (HV) mixing rule combined with non-random two-liquid (NRTL) activity coefficient model. The maximum average absolute relative deviation of pressure (AARDp) and the maximum average absolute deviation of vapor phase composition (AADy) are 0.67% and 0.005, respectively.

Experimental Investigation of Vapor–Liquid Equilibrium for 2,3,3,3-Tetrafluoropropene (HFO-1234yf) + trans-1,3,3,3-Tetrafluoropropene (HFO-1234ze(E)) at Temperatures from 284 to 334 K

The vapor–liquid equilibrium for the binary system (HFO-1234yf + HFO-1234ze(E)) has been investigated using a liquid-recirculation apparatus from 284 to 334 K. The Peng–Robinson equation of state with the Mathias–Copeman alpha function (PR-MC), combined with Wong–Sandler (WS) mixing rule and simplified Wong–Sandler (WS_S) mixing rule, respectively, was chosen to correlate all of the experimental data. The results correlated by PR-MC + WS + NRTL and PR-MC + WS_S + NRTL models showed a good agreement with the experimental data; the average absolute relative deviation of pressure (AARDp) was within 0.5%, and the average absolute deviation of the mole fraction of HFO-1234yf in the vapor phase (AADy1) was less than 0.002. This system exhibited no azeotropic behavior within the investigated temperature range. In addition, the relative volatilities of the system at each temperature were obtained.

Experimental investigation on vapor liquid equilibrium and azeotropic behavior for the 1,1,1,2-tetrafluoroethane (R134a) + propane (R290) system at temperatures from 253.15 to 303.15 K

Abstract This study reports a set of new vapor liquid equilibrium (VLE) data for the binary mixture of 1,1,1,2-tetrafluoroethane (R134a) + propane (R290) at temperatures from 253.15 to 303.15 K, and the saturated vapor pressures of R290 and R134a at temperatures ranging from 253.15 to 323.15 K using a recirculation apparatus with view windows. The VLE data were correlated with the well-known NRTL-RK, Wilson-RK, and UNIQ-RK models. The results indicated that all the models showed good agreement with the experimental data. The average absolute relative deviations of pressure (AARDp) were between 0.01% and 0.02%, while the average absolute deviations of vapor phase mole fraction (AADy) were between 0.0035 and 0.0041. Positive azeotropic behavior could be observed for the R134a + R290 system, and the azeotropic point data at six temperatures from 253.15 to 303.15 K were presented.

Experimental measurement of vapor-liquid equilibrium for 3,3,3-trifluoropropene(R1243zf) + 1,1,1,2-tetrafluoroethane(R134a) at temperatures from 243.150 to 293.150 K

Abstract New regulations have been approved that only low-GWP refrigerants will be used in developed countries. As mixed refrigerants especially positive azeotropic blends, R1243zf could be a promising substitute component for R134a with similar thermodynamic properties and low GWP. In this study, the VLE data for the binary system of R1243zf + R134a were measured with a recirculation method at six temperatures (243.150, 253.150, 263.150, 273.150, 283.150 and 293.150) K. The measurement uncertainties of the temperatures, pressures and compositions are estimated to be less than 5mK, 800 Pa, 0.005, respectively. All the experimental data were correlated by PR-vdW and PR-HV-NRTL model. The maximum average absolute relative deviation of pressure (AARDp) and average absolute deviation of vapor-phase mole fraction (AADy) for the PR-vdW model are 0.35% and 0.004, respectively, while the maximum AARDp and AADy for PR-HV-NRTL model are 0.29% and 0.004, respectively. Positive azeotropic behavior was exhibited at each temperature investigated.

Isothermal vapour-liquid equilibrium of (difluoromethane + trifluoroiodomethane) at temperatures ranging from 253.150 K to 293.150 K

In this paper, the isothermal vapour-liquid equilibrium (VLE) data for pure difluoromethane (R32) and trifluoroiodomethane (R13I1) and their binary mixtures have been measured based on a vapour – phase single recirculation method. The data were collected for five temperatures from 253.150 K to 293.150 K. The experimental VLE data were regressed by PR-MHV2-NRTL model and PR-vdW model. The deviation curves of pressures and vapour compositions for the binary system between experimental and calculated values were given. The results indicated that the maximum mean absolute relative deviation of pressure (MARDp) for PR-MHV2-NRTL is 0.54%, which shows a better fit than PR-vdW with a maximum MARDp of 2.73%. The maximum mean absolute deviation of vapour phase mole fraction (MADy) for PR-MHV2-NRTL and PR-vdW are 0.013 and 0.010, respectively. The azeotropic behaviours were found at T = (253.150, 263.150, 273.150) K, while the zeotropic behaviours were found at 283.150 K and 293.150 K.

Vapour-liquid equilibria for the binary systems of pentafluoroethane {(R125) + 2,3,3,3-tetrafluoroprop-1-ene (R1234yf)} and {trans-1,3,3,3-tetrafluoropropene R1234ze(E)}

In this work, isothermal vapour-liquid equilibrium (VLE) data for the binary mixtures of pentafluoroethane (R125) + 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-tetrafluoropene (R1234ze(E)) have been investigated. The experimental measurements were carried out by using the AnTLcirCapValVis analytical method over the temperature range from 283.15 K to 323.15 K. The standard uncertainties of temperature, pressure and mole fractions are 10 mK, 0.5 kPa and 0.005, respectively. The Peng-Robinson (PR) equation of state (EoS) and its modifications from Stryjek and Vera (PRSV and PRSV2) combined with Wong-Sandler (WS) mixing rule and the non-random two-liquid activity coefficient model (NRTL) were employed to correlate the parameters of binary mixtures, respectively. The PRSV2 + WS + NRTL model shows the best consistency with the experimental VLE data compared with the other two models (PR + WS + NRTL and PRSV + WS + NRTL). The average absolute relative deviation of pressure (AARD(p)) and average absolute deviation of vapour phase mole fraction (AAD(y)) are 0.10% and 0.0012 for R125 + R1234yf, 0.16% and 0.0014 for R125 + R1234ze(E), respectively. Both the experimental data and the calculated results imply that R125 + R1234yf and R125 + R1234ze(E) are zeotropic binary mixtures over the studied temperatures.

Isothermal (vapour-liquid) equilibrium for the binary {isobutane (R600a) + 3,3,3-trifluoropropene (R1243zf)}cc system at temperatures from 253.150 to 293.150 K

As one of the new generations of alternative refrigerants in the future, hydrofluoroolefins (HFOs) and mixed refrigerants containing HFOs have gradually attracted attention. In this study, the vapour + liquid equilibrium (VLE) for the binary system of {isobutane(R600a) + 3,3,3-trifluoropropene (R1243zf)} was measured with a recirculation method at five temperatures of (253.150, 263.150, 273.150, 283.150 and 293.150) K. The uncertainties of the temperatures, pressures, and compositions are estimated to be less than 5mK, 800 Pa, 0.005, respectively. The Peng-Robinson equations of state with the Huron-Vidal mixing rule involving the non-random two-liquid activity coefficient model (PR-HV-NRTL model) were employed to correlate all the experimental data which had good fitting results. The maximum average absolute relative deviation of pressure (AARDp) and the average absolute deviation of vapour-phase mole fraction (AADy) for the PR-HV-NRTL model is 0.21% and 0.004, respectively. Azeotropic behaviours were found at a high mole fraction of R1243zf.

Isothermal measurement and modeling of VLE properties for 2,3,3,3-tetrafluoroprop-1-ene + trifluoromethane + tetrafluoromethane ternary system at temperatures from 253.15 K to 273.15 K

Abstract At present, the difficulty in the research of auto cascade refrigeration system lies in the selection of the mixed refrigerant ratio and the design of system process. Accurate thermodynamic data is the key to solve those problems. In this paper, isothermal vapor liquid equilibrium (VLE) behavior was experimentally studied for the strongly-zeotropic ternary mixture 2,3,3,3-tetrafluoroprop-1-ene (R1234yf) + trifluoromethane (R23) + tetrafluoromethane (R14) at 253.15 K, 263.15 K, and 273.15 K. The pressures and the vapor mass fractions were found to be thermodynamically consistent and were satisfactorily correlated with the NRTL-RK model and the MUNIFAC-SRK model. The average absolute relative deviations of pressure (AARD-p), and the average absolute deviations of vapor phase mass fraction (AAD-y1, AAD-y2 and AAD-y3) are less than 0.25%, 0.0032, 0.0048 and 0.0040 for the MUNIFAC-SRK model, respectively, which are better than those of 0.4%, 0.0138, 0.0198 and 0.0049 for the NRTL-RK model. The results of the MUNIFAC-SRK model showed excellent agreement with the experimental values. The isothermal three-dimensional VLE behavior and the isothermal-isobaric ternary VLE diagrams under 1500 kPa were also established using a flash calculation method.

Isothermal (vapour-liquid) equilibrium for the binary {3,3,3-trifluoropropene (R1243zf) + propane(R290)} system at temperatures from 243.150 K to 288.150 K

New regulations have been approved that some refrigerants including R134a blends will be phased out. As mixed refrigerants especially positive azeotropic blends, R1243zf + R290 mixture could be a corresponding substitute for R134a blends with similar thermodynamic properties and low GWP. In this study, the VLE data for the binary system of R1243zf + R290 were measured with a recirculation method at six temperatures (243.150, 253.150, 263.150, 273.150, 283.150 and 288.150) K. The measurement uncertainties of the temperatures, pressures, and compositions are estimated to be less than 5mK, 800 Pa, 0.005, respectively. All the experimental data were correlated by PR-vdW and PR-HV-NRTL models. The maximum average absolute relative deviation of pressure (AARDp) and average absolute deviation of vapour-phase mole fraction (AADy) for the PR-vdW model is 0.41% and 0.004, respectively, while the maximum AARDp and AADy for PR-HV-NRTL model are 0.30% and 0.004, respectively. Positive azeotropic behavior was found at each measured temperature. Azeotropic behaviors were found at a high mole fraction of R290.

The investigation on the vapor-liquid phase equilibrium of (trifluoromethane + difluoromethane) system at temperatures ranging from (223.150 to 273.150) K

The trifluoromethane (R23) and difluoromethane (R32) are widely used in refrigeration and chemical industry. The isothermal vapor plus liquid equilibrium (VLE) data for the R23 plus R32 system were determined experimentally at six temperatures from 223.150 K to 273.150 K. Two models were employed to regress the experimental VLE data: Peng–Robinson (PR) equation of state with the one-parameter van der Waals (vdW) mixing rule; Peng–Robinson equation of state combined non-random two-liquid (NRTL) activity coefficient model with the modified Huron-Vidal two-order (MHV2) mixing rule. The maximum average absolute relative deviation of pressure (AARDp) and average absolute deviation of vapor phase mole fraction (AADy) for PR-vdW are 2.71% and 0.0175, respectively, while the maximum AARDp and AADy for PR-MHV2-NRTL are 1.53% and 0.0148, respectively.

Measurements of isothermal (vapour + liquid) equilibrium for the 1,1,2,2-1,1,2,2-tetrafluoroethane (R134) + cis-1,3,3,3-tetrafluoropropene (R1234ze(Z)) system at temperatures from (303.150 to 343.150) K

The isothermal (vapour+liquid) equilibrium data for the 1,1,2,2-1,1,2,2-tetrafluoroethane (R134)+cis-1,3,3,3-tetrafluoropropene (R1234ze(Z)) system were determined by the static-analytical method at five temperatures from (303.150 to 343.150)K. The standard uncertainties of the temperature, pressure and composition were less than 5mK, 0.0005MPa, and 0.005, respectively. The experimental results were correlated by the Peng–Robison (PR) equation of state (EoS) with the Huron–Vidal (HV) mixing rule involving the non-random two-liquid (NRTL) activity coefficient model. The correlated results show good agreement with the experimental data. The average absolute relative deviations of pressure are between 0.20% and 0.35%, while the average absolute deviations of vapour phase mole fraction lay between 0.006 and 0.007. Azeotropic behaviour can be observed at four temperatures from (303.150 to 333.150)K, while zeotropic behaviour can be found at 343.150K.

The investigation on the vapour liquid phase equilibrium of (ammonia + 1,1,1,2-tetrafluoroethane) system over the temperatures ranging from (243.150 to 283.150) K

To blend ammonia with some hydrofluorocarbons may give these mixed refrigerants lower flammability and global warming potential. In this paper, the isothermal vapour liquid equilibrium (VLE) of (ammonia+1,1,1,2-tetrafluoroethane) system at temperatures ranging from (243.150 to 283.150) K are presented. Two models were employed to regress the experimental VLE results, namely the Peng–Robinson (PR) equation of state with the simple van der waals (VDW) mixing rule; the Peng–Robinson equation of state combined non-random two-liquid (NRTL) activity coefficient model with the modified Huron-Vidal one-order (MHV1) mixing rule. The maximum average absolute relative deviation of pressure (AARDp) and average absolute deviation of the vapour phase mole fraction (AADy) for PR-VDW are 0.56% and 0.010, respectively, while the maximum AARDp and AADy for PR-MHV1-NRTL are 0.27% and 0.014, respectively. Positive azeotropic behaviour was exhibited at each temperature investigated.

The measurements of vapor liquid phase equilibrium for R717 + R152a system at temperatures ranging from 253.150 K to 293.150 K

In contrast to pure ammonia, some additives into it may provide better solubility of the mineral oils, higher refrigeration capacity and lower discharge temperature of the compressor. In this paper, the vapor liquid phase equilibrium for the ammonia + 1,1-difluoroethane system at temperatures ranging from 253.150 K to 293.150 K were studied. The Peng–Robinson equation of state with the Huron–Vidal mixing rule involving the non-random two-liquid activity coefficient model was employed to describe the VLE behavior of the system concerned. The maximum average absolute relative deviation of pressure and average absolute deviation of vapor phase are 0.31% and 0.009, respectively. A positive azeotropic behavior was exhibited at the experimental temperature range.

Measurements and correlations of isothermal (vapour + liquid) equilibrium for the {isobutane (R600a) + cis-1,3,3,3-tetrafluoropropene (R1234ze(Z))} system at temperatures from (303.150 to 353.150) K

In this paper, the (vapour+liquid) phase equilibrium for the (isobutane+cis-1,3,3,3-tetrafluoropropene) system was measured by the static-analytical method at six temperatures from (303.150 to 353.150)K. The combined standard uncertainties of the temperature, pressure and composition were less than ±5mK, ±0.0005MPa and ±0.005, respectively. The experimental results were correlated by means of the Peng–Robison (PR) equation of state (EoS) with Van der Waals (VDW) mixing rule and Huron–Vidal (HV) mixing rule involving the non-random two-liquid (NRTL) activity coefficient model. Good consistency is found by both models. The average absolute relative deviations of pressure are between 0.44% and 0.58% for the PR-VDW model, while the average absolute relative deviations of pressure are between 0.12% and 0.44% for the PR-HV-NRTL model. The average absolute deviations of vapour phase mole fraction lay between 0.007 and 0.008 for the PR-VDW model, while the average absolute deviations of vapour phase mole fraction lay between 0.004 and 0.008 for the PR-HV-NRTL model. The results show that the PR-HV-NRTL model has better performance than that of the PR-VDW model for the binary system. Obviously an azeotropic behaviour can be observed for the system.

Isothermal (vapour + liquid) equilibrium measurements and correlation for the {n-butane (R600) + 1,1,1,3,3-pentafluoropropane (R245fa)} system at temperatures from (303.150 to 373.150) K

The isothermal VLE for the {n-butane (R600)+1,1,1,3,3-pentafluoropropane (R245fa)} system was measured at five temperatures from (303.150 to 373.150)K based on the static-analytical method. The experimental values were correlated by the Peng–Robison equation of state with the Huron–Vidal mixing rule involving the non-random two-liquid (NRTL) activity coefficient model. The results show that the experimental values are in good agreement with the calculated value. The maximum average absolute relative deviation of pressure and vapour phase mole fraction are 0.35%, 0.0047, respectively. Obviously azeotropic behaviour can be observed for the binary system.

(Vapor + liquid) phase equilibrium measurements for {trifluoroiodomethane (R13I1) + propane (R290)} from T = (258.150 to 283.150) K

In this paper, the (vapor+liquid) equilibrium data for (R13I1+R290) were measured by a vapor-recirculation apparatus at temperatures from (258.150 to 283.150)K. The VLE data were correlated by the Peng–Robinson equation of state with two different models, the van der Waals mixing rule, and the Huron–Vidal mixing rule involving the NRTL activity coefficient model. Good agreements were found between the calculated data and the experimental data. The maximum average absolute relative deviation of pressure (AARD p) was 0.48%, while the maximum average absolute deviation of composition (AAD y) was 0.0040. Meanwhile, zeotropic behavior can be found for the measured system in this study. The total combined standard uncertainties for temperature, pressure and composition measurements were ±5mK, ±0.0005MPa and ±0.005, respectively.