Comment on Gibbs Density Surface of Fluid Argon, L.V. Woodcock, Int. J. Thermophys. (2014) 35:1770–1784

Sengers, J. V.; Анисимов, М. А.

doi:10.1007/s10765-015-1954-8

Cited by 12 publications

(15 citation statements)

References 22 publications

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“…It has been the subject of a microgravity experiment aboard the NASA Space Shuttle [27] that appeared to confirm the erroneous result obtained some 25 years earlier by Voronel and his colleagues [24,25]. We have obtained the original published data points of the space shuttle experiments (see acknowledgements) and have plotted them alongside the U(T) V equation-of-state from the NIST data bank parameterized as a simple quadratic for T < T c and linear for T > T c equations in Figure 12a.…”

Section: Sf 6 Near Critical Isochorsmentioning

confidence: 76%

“…Despite using complex equations-of-state that could accommodate the concept of a critical density at the node of a parabola, the NIST thermodynamic data bank is still valid as "experimental" evidence that the 1965 Washington proclamation of 'a universality theory' was fundamentally incorrect. It was based upon a misinterpretation of the isochoric heat capacity Cv for T < Tc, and spurious results at, or millikelvins greater than, Tc [24,25]. Along any isochore within the critical divide there can be no divergence of the isochoric heat capacity.…”

Section: Argon Critical Isotherm and Isochoresmentioning

confidence: 99%

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Thermodynamic Fluid Equations-of-State

Woodcock

2018

Entropy

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As experimental measurements of thermodynamic properties have improved in accuracy, to five or six figures, over the decades, cubic equations that are widely used for modern thermodynamic fluid property data banks require ever-increasing numbers of terms with more fitted parameters. Functional forms with continuity for Gibbs density surface ρ(p,T) which accommodate a critical-point singularity are fundamentally inappropriate in the vicinity of the critical temperature (T c ) and pressure (p c ) and in the supercritical density mid-range between gas-and liquid-like states. A mesophase, confined within percolation transition loci that bound the gas-and liquid-state by third-order discontinuities in derivatives of the Gibbs energy, has been identified. There is no critical-point singularity at T c on Gibbs density surface and no continuity of gas and liquid. When appropriate functional forms are used for each state separately, we find that the mesophase pressure functions are linear. The negative and positive deviations, for both gas and liquid states, on either side of the mesophase, are accurately represented by three or four-term virial expansions. All gaseous states require only known virial coefficients, and physical constants belonging to the fluid, i.e., Boyle temperature (T B ), critical temperature (T c ), critical pressure (p c ) and coexisting densities of gas (ρ cG ) and liquid (ρ cL ) along the critical isotherm. A notable finding for simple fluids is that for all gaseous states below T B , the contribution of the fourth virial term is negligible within experimental uncertainty. Use may be made of a symmetry between gas and liquid states in the state function rigidity (dp/dρ) T to specify lower-order liquid-state coefficients. Preliminary results for selected isotherms and isochores are presented for the exemplary fluids, CO 2 , argon, water and SF 6 , with focus on the supercritical mesophase and critical region.

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Section: Sf 6 Near Critical Isochorsmentioning

confidence: 76%

Section: Argon Critical Isotherm and Isochoresmentioning

confidence: 99%

Thermodynamic Fluid Equations-of-State

Woodcock

2018

Entropy

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“…According to the "mesophase" hypothesis at critical and supercritical temperatures on the thermodynamic (density, pressure)-plane exists a region where the pure substance is in "meso-phase", which consists of small clusters that are gas like and clusters of macroscopic size that are liquid like, there is exist a line of critical points over a finite range of densities at critical temperature and pressure instead of single critical point, and the pressure in the "meso-phase" is linear function of density. This hypothesis is reminiscent of an old concept of the supercritical fluid as a mixture of "gasons" and "liquidons" that has turned out to be inconsistent with the experimental evidence [4,5].…”

Section: Introductionmentioning

confidence: 99%

“…Some predictions of the "meso-phase" hypothesis were criticized by Sengers and Anisimov [4] and Umirzakov [27]. According to [4] in contrast to the conjecture of Woodcock, there is no reliable experimental evidence to doubt the existence of a single critical point in the thermodynamic limit and of the validity of the scaling theory for critical thermodynamic behavior.…”

Section: Introductionmentioning

confidence: 99%

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Failures of “Meso-Phase” Hypothesis Near Vapor–Liquid Critical Point

Umirzakov

2019

Int J Thermophys

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It is shown that the "meso-phase" hypothesis of Woodcock L. V. fails to describe quantitatively and qualitatively the isochoric and isobaric heat capacities, speed of sound, long wavelength limit of the structural factor, isothermal compressibility, density fluctuations, Joule-Thompson coefficient and isothermal throttling coefficient of argon in the "meso-phase" region. It is also shown that VdW-EOS can describe qualitatively the excess Gibbs energy and rigidity of argon near critical point.Keywords Critical point · First-order phase transition · Phase equilibrium · Argon · Heat capacity Comparison of predictions of "meso-phase" hypothesis with available data for argonThe predictions of the "meso-phase" hypothesis for the isochoric and isobaric heat capacities, speed of sound, isothermal compressibility, density fluctuations, optic (long wavelength) limit of the structural factor, Helmholtz energy, Gibbs energy, entropy, internal energy, enthalpy, Joule-Thomson coefficient and isothermal throttling coefficient of argon are obtained and discussed in Chapter 2.1. The expressions to define the above physical properties of argon using TSW-EOS [17] are given in Chapter 2.2. The comparison of the predictions of the "meso-phase" hypothesis and TSW-EOS for argon is presented and discussed in Chapter 2.3. Predictions of the "meso-phase" hypothesis for argonAccording to [26] pressure ) , ( T p M  of the "meso-phase", which exists in the density interval

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On the Interpretation of Near-Critical Gas–Liquid Heat Capacities

Woodcock

2017

Int J Thermophys

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Comment on Gibbs Density Surface of Fluid Argon, L.V. Woodcock, Int. J. Thermophys. (2014) 35:1770–1784

Cited by 12 publications

References 22 publications

Thermodynamic Fluid Equations-of-State

Thermodynamic Fluid Equations-of-State

Failures of “Meso-Phase” Hypothesis Near Vapor–Liquid Critical Point

On the Interpretation of Near-Critical Gas–Liquid Heat Capacities

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