Thermodynamic Properties of Methanol in the Critical and Supercritical Regions |
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Authors: | I M Abdulagatov N G Polikhronidi A Abdurashidova S B Kiselev J F Ely |
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Affiliation: | (1) Institute for Geothermal Problems of the Dagestan Scientific Center of the Russian Academy of Sciences, Shamilya Street 39-A, 367003 Makhachkala, Dagestan, Russia;(2) Institute of Physics of the Dagestan Scientific Center of the Russian Academy of Sciences, YaragskogoStreet 94, 367005 Makhachkala, Dagestan, Russia;(3) Chemical Engineering Department, Colorado School of Mines, Golden, Colorado, 80401-1887, U.S.A |
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Abstract: | The isochoric heat capacity of pure methanol in the temperature range from 482 to 533 K, at near-critical densities between
274.87 and 331.59 kg· m−3, has been measured by using a high-temperature and high-pressure nearly constant volume adiabatic calorimeter. The measurements
were performed in the single- and two-phase regions including along the coexistence curve. Uncertainties of the isochoric
heat capacity measurements are estimated to be within 2%. The single- and two-phase isochoric heat capacities, temperatures,
and densities at saturation were extracted from experimental data for each measured isochore. The critical temperature (Tc = 512.78±0.02K) and the critical density (ρc = 277.49±2 kg · m−3) for pure methanol were derived from the isochoric heat-capacity measurements by using the well-established method of quasi-static
thermograms. The results of the CVVT measurements together with recent new experimental PVT data for pure methanol were used to develop a thermodynamically self-consistent Helmholtz free-energy parametric crossover
model, CREOS97-04. The accuracy of the crossover model was confirmed by a comprehensive comparison with available experimental
data for pure methanol and values calculated with various multiparameter equations of state and correlations. In the critical
and supercritical regions at 0.98Tc≤ T ≤ 1.5Tc and in the density range 0.35ρc ≤ ρ leq 1.65 ρc, CREOS97-04 represents all available experimental thermodynamic data for pure methanol to within their experimental uncertainties. |
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Keywords: | coexistence curve critical region crossover equation of state methanol isochoric heat capacity thermodynamic properties |
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