scholarly journals Density Measurements of (0.99 Methane + 0.01 Butane) and (0.98 Methane + 0.02 Isopentane) over the Temperature Range from (100 to 160) K at Pressures up to 10.8 MPa

2020 ◽  
Vol 41 (11) ◽  
Author(s):  
Philipp Eckmann ◽  
Nils von Preetzmann ◽  
Giuseppe Cavuoto ◽  
Jianrong Li ◽  
Adriaan van der Veen ◽  
...  
Keyword(s):  
Equation Of State ◽  
Binary Mixtures ◽  
Single Phase ◽  
Measurement Procedure ◽  
Magnetic Suspension ◽  
Saturated Liquid ◽  
Time Saving ◽  
Homogeneous Liquid ◽  
Combined Uncertainty ◽  
Phase Liquid

Abstract Densities of two methane-rich binary mixtures were measured in the homogeneous liquid and the supercritical region at temperatures between (100 and 160) K using a low-temperature single-sinker magnetic-suspension densimeter. For each mixture, four isotherms were studied over the pressure range from (0.3 to 10.8) MPa. Molar compositions of the gravimetrically prepared methane-rich binary mixtures were approximately 0.01 butane and 0.02 isopentane, respectively, with the balance being methane. The relative expanded combined uncertainty (k = 2) of the experimental densities was estimated to be in the range of (0.02 to 0.06) %. Due to a supercritical liquefaction procedure and the integration of a special VLE-cell, it was possible to measure densities in the homogeneous liquid phase without changing the composition of the liquefied mixture. Based on the supercritical liquefaction procedure, a new time-saving measurement procedure was developed and applied. Moreover, saturated-liquid densities were determined by extrapolation of the experimental single-phase liquid densities to the vapor pressure calculated with an equation of state (EOS); here, the relative expanded combined uncertainty (k = 2) is less than 0.05 % in most cases. The new experimental results were compared with the GERG-2008 equation of state, the EOS-LNG and the enhanced revised Klosek and McKinley (ERKM) method.

scholarly journals Density Measurements of Two Liquefied Biomethane-Like Mixtures over the Temperature Range from (100 to 180) K at Pressures up to 9.0 MPa

2021 ◽  
Vol 42 (3) ◽  
Author(s):  
Giuseppe Cavuoto ◽  
Nils von Preetzmann ◽  
Philipp Eckmann ◽  
Jianrong Li ◽  
Adriaan M. H. van der Veen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Liquid Phase ◽  
Equation Of State ◽  
Single Phase ◽  
Magnetic Suspension ◽  
Saturated Liquid ◽  
Homogeneous Liquid ◽  
Combined Uncertainty ◽  
Phase Liquid ◽  
Cell Densities

AbstractDensities of two synthetic biomethane-like mixtures were measured in the homogeneous liquid phase and the supercritical region using a low-temperature single-sinker magnetic-suspension densimeter. Both mixtures consist of methane, nitrogen, hydrogen and oxygen, whereas the second mixture additionally contains carbon dioxide. For the first mixture, four isotherms from (100 to 160) K were studied over the pressure range from (1.5 to 6.6) MPa. The second mixture was investigated along three isotherms from (140 to 180) K at pressures of (2.6 to 9.0) MPa, where only the densities at 180 K are usable due to solidification of the carbon dioxide at the lower temperatures. The relative expanded combined uncertainty (k = 2) of the experimental densities was estimated to be in the range of (0.022 to 0.027)  % for the first mixture and (0.046 to 0.054)  % for the second mixture, respectively. Due to a supercritical liquefaction procedure and the integration of a special VLE-cell, densities in the homogeneous liquid phase could be measured without changing the composition of the liquefied mixture. Moreover, saturated-liquid densities were determined by extrapolation of the experimental single-phase liquid densities to the vapor pressure, which was determined experimentally for the mixture without carbon dioxide and calculated with an equation of state (EOS) for the mixture containing carbon dioxide. The relative expanded combined uncertainty (k = 2) of the saturated-liquid densities is less than 0.08 % in most cases. The new experimental results were compared with the GERG-2008 equation of state; the deviations are less than 0.17 %.

A Simplified Presentation of Equations for the Thermodynamic Properties of Dichlorodifluoromethane, CCl2F2 (Refrigerant-12)

1969 ◽  
Vol 11 (4) ◽  
pp. 376-383
Author(s):  
R. W. Haywood
Keyword(s):  
Equation Of State ◽  
Thermodynamic Properties ◽  
Characteristic Equation ◽  
Single Phase ◽  
Saturation Pressure ◽  
Phase Region ◽  
Pure Substance ◽  
Coherent System ◽  
Saturated Liquid ◽  
System Of Units

The paper commences with a general treatment illustrating the advantages of writing the equation of state of a pure substance in characteristic (canonical or fundamental) form, from which expressions for all other thermodynamic properties can be written down in terms only of the characteristic function and its partial derivatives. In this way, thermodynamic consistency between the equations for the different properties is automatically ensured. The initial difficulties in constructing an equation of state in characteristic form are briefly discussed, and it is shown how the characteristic equation may be built up from an existing p-v-T equation of state and an equation for the specific heat capacity at zero pressure. An existing set of equations for the single-phase region of Refrigerant-12 is transformed in this way into a single characteristic equation of state from which, through given simple expressions, all other thermodynamic properties may be computed. The equation of state is expressed dimensionlessly in reduced co-ordinates so that it may be used with equal facility in any coherent system of units. For the sake of completeness, other existing equations for the saturation pressure and for the saturated liquid have been put into dimensionless form and are given in the paper.

Volume-translated Peng–Robinson equation of state for saturated and single-phase liquid densities

2012 ◽  
Vol 335 ◽  
pp. 74-87 ◽  
Author(s):  
Agelia M. Abudour ◽  
Sayeed A. Mohammad ◽  
Robert L. Robinson ◽  
Khaled A.M. Gasem
Keyword(s):  
Equation Of State ◽  
Single Phase ◽  
Phase Liquid ◽  
Robinson Equation

Estimation of P-V-T behaviour of gas mixtures

1982 ◽  
Vol 47 (2) ◽  
pp. 371-383
Author(s):  
Vladimíra Měřičková ◽  
Josef P. Novák ◽  
Jiří Pick
Keyword(s):  
Equation Of State ◽  
Binary Mixtures ◽  
Gas Mixtures

A review of methods is presented which allow to determine the P-V-T behaviour of gas mixtures. This review is based on the computations performed for about 2 200 P-V-T-X data of 12 binary mixtures. The method of combination of the equation-of-state constants, the Joffe method and the modified Bartlett rule proved to be the most suitable.

Critical consolute point in hard-sphere binary mixtures: Effect of the value of the eighth and higher virial coefficients on its location

2010 ◽  
Vol 75 (3) ◽  
pp. 359-369 ◽  
Author(s):  
Mariano López De Haro ◽  
Anatol Malijevský ◽  
Stanislav Labík
Keyword(s):  
Equation Of State ◽  
Binary Mixtures ◽  
Hard Sphere ◽  
Hard Spheres ◽  
Virial Coefficients ◽  
Fluid Mixture ◽  
Binary Fluid ◽  
Virial Series ◽  
Consolute Point ◽  
Critical Constants

Various truncations for the virial series of a binary fluid mixture of additive hard spheres are used to analyze the location of the critical consolute point of this system for different size asymmetries. The effect of uncertainties in the values of the eighth virial coefficients on the resulting critical constants is assessed. It is also shown that a replacement of the exact virial coefficients in lieu of the corresponding coefficients in the virial expansion of the analytical Boublík–Mansoori–Carnahan–Starling–Leland equation of state, which still leads to an analytical equation of state, may lead to a critical consolute point in the system.

scholarly journals Density Measurements of an Air-Like Binary Mixture over the Temperature Range from 100 K to 298.15 K at Pressures up to 8.0 MPa

2021 ◽  
Vol 42 (9) ◽  
Author(s):  
Nils von Preetzmann ◽  
Reiner Kleinrahm ◽  
Philipp Eckmann ◽  
Giuseppe Cavuoto ◽  
Markus Richter
Keyword(s):  
Binary Mixture ◽  
Saturated Vapor ◽  
Saturation Pressure ◽  
Transmission Error ◽  
Magnetic Suspension ◽  
Mixture Component ◽  
Liquid Region ◽  
Force Transmission ◽  
Temperature Range ◽  
Combined Uncertainty

AbstractDensities of an air-like binary mixture (0.2094 oxygen + 0.7906 nitrogen, mole fractions) were measured along six isotherms over the temperature range from 100 K to 298.15 K at pressures up to 8.0 MPa, using a low-temperature single-sinker magnetic suspension densimeter. The measurements were carried out at T = (100, 115, and 130) K in the homogeneous gas and liquid region, and at T = (145, 220, and 298.15) K in the supercritical region (critical temperature TC = 132.35 K); in total, we present results for 52 (T, p) state points. The relative expanded combined uncertainty (k = 2) of the experimental densities was estimated to be between 0.03 % and 0.13 %, except for four values near the critical point. The largest error is caused by the magnetic suspension coupling in combination with the mixture component oxygen, which is strongly paramagnetic; the resulting force transmission error is up to 1.1 %. However, this error can be corrected with a proven correction model to an uncertainty contribution in density of less than 0.044 %. Due to a supercritical liquefaction procedure and the integration of a special VLE-cell, it was possible to measure densities in the homogeneous liquid phase without changing the composition of the liquefied mixture. Moreover, saturated liquid and saturated vapor densities were determined at T = (100, 115, and 130) K by extrapolation of the experimental single-phase densities to the saturation pressure. The new experimental results were compared with the mixture model of Lemmon et al. for the system (nitrogen + argon + oxygen) and the GERG-2008 equation of state.

scholarly journals Speeds of Sound in Methanol at Temperatures from 233.33 to 353.21 K at Pressures up to 20 MPa

2021 ◽  
Vol 42 (5) ◽  
Author(s):  
Christian W. Scholz ◽  
Roland Span
Keyword(s):  
Equation Of State ◽  
Path Length ◽  
Speeds Of Sound ◽  
Pulse Timing ◽  
Combined Uncertainty ◽  
Pulse Echo

AbstractWe report experimental speeds of sound in methanol. Measurements were conducted at temperatures from 233 to 353 K with pressures up to 20 MPa using the double-path length pulse-echo technique. The relative expanded combined uncertainty (k = 2) in measurement was estimated to vary from 0.012 to 0.014%, considering contributions from temperature, pressure, path length calibration, pulse timing, and purity of the sample. Experimental speeds of sound gained in the scope of this work were compared with the equation of state by de Reuck and Craven, as well as with further data from literature.

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