THERMODYNAMIC PROPERTIES OF XENON IN THE CRITICAL REGION

1954 ◽  
Vol 32 (2) ◽  
pp. 164-173 ◽  
Author(s):  
H. W. Habgood ◽  
W. G. Schneider
Keyword(s):  
Critical Temperature ◽  
Thermodynamic Properties ◽  
Critical Region ◽  
High Frequency ◽  
Critical Density ◽  
Preceding Paper ◽  
Acoustic Data ◽  
Dispersion Effects ◽  
Acoustical Data ◽  
Good Agreement

Using the detailed compressibility data in the critical region of xenon given in the preceding paper, supplemented by measurements of Beattie, Barriault, and Brierley over a wider range of temperatures and densities, thermodynamic properties have been calculated for the critical region—extending from the critical temperature to 50° above it and from low densities to somewhat above the critical density. The values of Cυ at the critical density are in good agreement with those calculated from acoustical data at temperatures higher than Tc + 1°; closer to the critical temperature however, the Cυ values derived from the equation of state data become much greater than those derived from the acoustic data. This difference can be accounted for by dispersion effects in the high frequency acoustic data near the critical point.

Diffusion of a solute in dilute solution in a supercritical fluid

1991 ◽  
Vol 433 (1887) ◽  
pp. 63-79 ◽  
Keyword(s):  
Diffusion Coefficient ◽  
Critical Temperature ◽  
Equation Of State ◽  
Supercritical Fluid ◽  
Critical Region ◽  
Critical Density ◽  
Partial Molar Volumes ◽  
Dilute Solution ◽  
Binary Diffusion Coefficient ◽  
Binary Diffusion

The experimental evidence for the behaviour of the binary diffusion coefficient for a solute in dilute solution in a supercritical fluid (a fluid above its critical temperature and pressure) is reviewed. Measurements at very low dilution, particularly by the Taylor dispersion technique, indicate that, at constant temperature a few degrees above the critical temperature, the product of density and the diffusion coefficient exhibits a small, continuous and undramatic variation from zero density to well above the critical density. However, some measurements made at higher, but still very low concentrations (e.g. with mole fractions around 10 -3 ), show a lowering of the coefficient in the critical region. The equations, based on non-equilibrium thermodynamics, are put into a form in which the behaviour of the binary diffusion coefficient in the critical region, but not very close to the critical point, may be examined using an equation of state. Calculations for naphthalene in solution in carbon dioxide are carried out using the van der Waals equation of state for mixtures to indicate the form and order of magnitude of the ‘anomalous’ lowering of the coefficient, and especially its dependence on concentration. These indicate a substantial effect even at naphthalene mole fractions of 4.0 x 10 -4 or less and a temperatures 1, 3 and 9 K above the critical temperature of the pure solvent. In addition the flux of a solute in a supercritical fluid in the critical region with respect to space or cell-fixed coordinates is discussed. Because of the large and negative partial molar volumes of solutes like naphthalene in this region, the frames of reference, according to which the diffusion coefficients are defined, can be caused to move rapidly, commonly towards the source of concentration. Thus fluxes of solute with respect to space-fixed coordinates are further substantially reduced in the critical region. The combination of the lowering of the diffusion coefficient and barycentric motion can therefore cause a very significant reduction of solute mass transfer in the critical region and may be the explanation of the sometimes very large diffusion anomalies observed experimentally.

Thermodynamic Properties of Refrigerant-Absorbent Pairs

1987 ◽  
Vol 109 (1) ◽  
pp. 58-62
Author(s):  
S. C. Bhaduri ◽  
H. K. Varma
Keyword(s):  
Experimental Data ◽  
Dipole Moment ◽  
Critical Temperature ◽  
Thermodynamic Properties ◽  
Analytical Method ◽  
Critical Pressure ◽  
Critical Volume ◽  
Polar Molecules ◽  
Experimental Dipole Moment ◽  
Good Agreement

An analytical method has been proposed to calculate thermodynamic properties of refrigerant-absorbent mixtures of polar molecules. The critical pressure, critical temperature, critical volume and experimental dipole moment of pure components are required in the proposed method. The calculated properties have been compared with the available experimental data and results reported in the literature. The comparison shows very good agreement. Thus, this method is recommended for use with refrigerant-absorbent pairs having polar molecules.

PVT MEASUREMENTS IN THE CRITICAL REGION OF XENON

1954 ◽  
Vol 32 (2) ◽  
pp. 98-112 ◽  
Author(s):  
H. W. Habgood ◽  
W. G. Schneider
Keyword(s):  
Critical Temperature ◽  
Critical Point ◽  
Critical Region ◽  
Critical Pressure ◽  
Critical Density ◽  
Van Der Waals Equation ◽  
The Third ◽  
Critical Isotherm ◽  
Pvt Measurements ◽  
Derivatives Of

Extensive PVT measurements of xenon extending from 1.8° above the critical temperature to the critical temperature, and in a few cases to 4 ° below the critical temperature, have been carried out at densities ranging from somewhat above the critical density to well below. In order to make the corrections for hydrostatic head small and easily calculable, a bomb having a height of only 1.0 cm. was used in the present measurements. The previously reported value for the critical temperature 16.590° is confirmed. The critical density is estimated to be 1.099 ± 0.002 gm./ml. compared with 1.105 gm./ml. found previously. The critical pressure is found to be 57.636 ± 0.005 atm.The isotherms at temperatures above the temperatures of meniscus disappearance do not appear to have any flat portions. However, the critical isotherm is considerably flatter and broader over a range of densities than that corresponding to a van der Waals equation, and at the critical point the third and fourth derivatives of pressure with respect to volume appear to be zero.

A Rational Equation of State for Water and Water Vapor in the Critical Region

1964 ◽  
Vol 86 (3) ◽  
pp. 320-326 ◽  
Author(s):  
E. S. Nowak
Keyword(s):  
Water Vapor ◽  
Equation Of State ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Critical Point ◽  
Critical Region ◽  
Constant Pressure ◽  
Parametric Equation ◽  
Enthalpy And Entropy ◽  
Specific Volumes

A parametric equation of state was derived for water and water vapor in the critical region from experimental P-V-T data. It is valid in that part of the critical region encompassed by pressures from 3000 to 4000 psia, specific volumes from 0.0400 to 0.1100 ft3/lb, and temperatures from 698 to 752 deg F. The equation of state satisfies all of the known conditions at the critical point. It also satisfies the conditions along certain of the boundaries which probably separate “supercritical liquid” from “supercritical vapor.” The equation of state, though quite simple in form, is probably superior to any equation heretofore derived for water and water vapor in the critical region. Specifically, the deviations between the measured and computed values of pressure in the large majority of the cases were within three parts in one thousand. This coincides approximately with the overall uncertainty in P-V-T measurements. In view of these factors, the author recommends that the equation be used to derive values for such thermodynamic properties as specific heat at constant pressure, enthalpy, and entropy in the critical region.

Estimation of the Thermodynamic Properties of Branched Hydrocarbons

2000 ◽  
Vol 122 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Hui He ◽  
Mohamad Metghalchi ◽  
James C. Keck
Keyword(s):  
Thermodynamic Properties ◽  
Degrees Of Freedom ◽  
Statistical Thermodynamic ◽  
Motion Modes ◽  
Branched Alkanes ◽  
Branched Hydrocarbons ◽  
Wide Range ◽  
On Line ◽  
Kinetic Calculations ◽  
Good Agreement

A simple model has been developed to estimate the sensible thermodynamic properties such as Gibbs free energy, enthalpy, heat capacity, and entropy of hydrocarbons over a wide range of temperatures with special attention to the branched molecules. The model is based on statistical thermodynamic expressions incorporating translational, rotational and vibrational motions of the atoms. A method to determine the number of degrees of freedom for different motion modes (bending and torsion) has been established. Branched rotational groups, such as CH3 and OH, have been considered. A modification of the characteristic temperatures for different motion mode has been made which improves the agreement with the exact values for simple cases. The properties of branched alkanes up to 2,3,4,-trimthylpentane have been calculated and the results are in good agreement with the experimental data. A relatively small number of parameters are needed in this model to estimate the sensible thermodynamic properties of a wide range of species. The model may also be used to estimate the properties of molecules and their isomers, which have not been measured, and is simple enough to be easily programmed as a subroutine for on-line kinetic calculations. [S0195-0738(00)00902-X]

Critical constants and density dependence of the Lorenz–Lorentz coefficient for germane

1978 ◽  
Vol 56 (9) ◽  
pp. 1140-1141 ◽  
Author(s):  
P. Palffy-Muhoray ◽  
D. Balzarini
Keyword(s):  
Critical Temperature ◽  
Density Dependence ◽  
Experimental Error ◽  
Critical Density ◽  
Coexistence Curve ◽  
Index Of Refraction ◽  
Density Range ◽  
Temperature Range ◽  
Critical Constants

The index of refraction at 6328 Å has been measured for germane in the density range 0.15 to 0.9 g/cm3. The temperature and density ranges over which measurements are made are near the coexistence curve. The coefficient in the Lorenz–Lorentz expression, [Formula: see text], is constant to within 0.5% within experimental error for the temperature range and density range studied. The coefficient is slightly higher near the critical density. The critical density is measured to be 0.503 g/cm3. The critical temperature is measured to be 38.92 °C.

Thermodynamic properties of charged ideal spin-1 bosons in a trap under a magnetic field

2014 ◽  
Vol 28 (26) ◽  
pp. 1450206 ◽  
Author(s):  
Yushan Li
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
External Magnetic Field ◽  
Thermodynamic Properties ◽  
Bose Gases ◽  
Spin Factor ◽  
Classical Approximation ◽  
Spinless Case

Thermodynamics of trapped charged ideal spin-1 bosons confined in a magnetic field are investigated within semi-classical approximation and truncated-summation approach. It is shown that the critical temperature increases slightly at the first, and then decreases slowly with increasing external magnetic field. Charged spin-1 Bose gases present a crossover from diamagnetism to paramagnetism as the spin factor increases. Charged spin-1 Bose gases exhibit distinct thermodynamic behaviors from the spinless case.

Antiferromagnetic exchange in triclinic crystals of tetra-u-benzoato- bits (4-methylquinoline) dicobalt II

1978 ◽  
Vol 360 (1701) ◽  
pp. 191-210 ◽  
Keyword(s):  
Cobalt Complex ◽  
Preceding Paper ◽  
Transverse Magnetic ◽  
Antiferromagnetic Coupling ◽  
Temperature Range ◽  
General Terms ◽  
Carboxylate Groups ◽  
A New Technique ◽  
Unambiguous Conclusion ◽  
Good Agreement

The magnetic susceptibilities of tetra- u -benzoato- bis (4-methylquinoline) dicobalt ii have been measured and interpreted within the theoretical model described in the preceding paper. Crystals of the title complex are triclinic, a circumstance which has lead to the development of a new technique for the measurement of triclinic crystal susceptibilities using a Faraday balance. The technique is discussed in general terms and is applicable with Faraday equipment employing either longitudinal or, as here, transverse magnetic fields. The magnetic tensor for this binuclear cobalt complex has been determined throughout the temperature range 20- 300 K. Good agreement between these results and those calculated from the quantum mechanical model have been obtained in the temperature range 90-300 K. At lower temperatures, a probable small paramagnetic impurity prevents useful theoretical treatm ent. There emerges an unambiguous conclusion that the antiferromagnetic coupling between the cobalt atoms is almost completely determined by interaction between metal xy orbitals, presumably via a superexchange process involving the delocalized n bonding framework of the bridging carboxylate groups.

Hypersonic Velocity, Absorption and Relaxation in Molten CSNO3

1977 ◽  
Vol 32 (1) ◽  
pp. 57-60 ◽  
Author(s):  
H. E. Gunilla Knape ◽  
Lena M. Torell
Keyword(s):  
Relaxation Time ◽  
High Frequency ◽  
Viscosity Coefficient ◽  
Sound Waves ◽  
Frequency Range ◽  
Ultrasonic Velocities ◽  
Hypersonic Velocity ◽  
Frequency Shifts ◽  
Bulk Viscosity Coefficient ◽  
Good Agreement

Abstract Brillouin spectra of molten CSNO3 were investigated for scattering angles between 40 and 140° and in a temperature interval of 420-520 °C. An Ar+ singlemode laser was used for excitation and the total instrumental width was ~265 MHz. The measured frequency shifts and linewidths of the Brillouin components were used to determine velocities and attenuations of thermal sound waves in the frequency range 2.3-7.0 GHz. A dispersion of 4-5% was found between the present hyper­ sonic velocities and reported ultrasonic velocities. A considerable decrease in attenuation with frequency was observed in the investigated frequency range, with the value at high frequency ap­ proaching the classical attenuation. The results are in good agreement with Mountain's theory of a single relaxation time. The relaxation time of the bulk viscosity coefficient was calculated to 1.2×10-10S.

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