Measurements of the isochoric heat capacity, the critical point (Tc, pc) and vapor-liquid coexistence curve (Ts, ps) of high-purity toluene near the critical point

Published

January 15, 2008

Author(s)

Ilmutdin Abdulagatov, Nikolai G. Polikhronidi, Thomas J. Bruno, Rabiyat G. Batyrova, Genadii V. Stepanov

Abstract

Isochoric heat capacities, phase boundary properties and the critical parameters for high purity (0.9999 mole fraction) toluene have been measured using a high temperature, high pressure, nearly constant volume adiabatic calorimeter and quasi-static thermograms techniques. Measurements were made at three selected liquid and vapor isochores (777.8, 555.25, and 214.64) kg×m^-3 in the temperature range from (379 to 591) K. For 5 near-critical isochores (268.68, 281.68, 296.62, 301.52, and 318.28) kg×m^-3 the measurements were made in the immediate vicinity of the coexistence curve in order to accurately determine the phase transition temperatures (shape of the coexistence curve near the critical point) and the critical parameters . The total uncertainty of heat capacity, density, and temperature measurements were estimated to be less than 2 %, 0.06 %, and 15 mK, respectively. The uncertainties reported in this paper are expanded uncertainties at the 95 % confidence level with a coverage factor of k=2. The uncertainty of the phase transition and the critical temperature values was 0.02 K. The Krichevskii parameter for the some toluene contained binary mixtures was calculated. The derived values of the Krichevskii parameter were used to estimate the effect of dilute impurities on the critical parameters of toluene. The measured values of saturated density near the critical point were interpreted in terms of the "complete scaling" theory in order to study singularity behavior of the coexistence curve diameter. The measured isochoric heat capacities and saturated densities were compared with the data reported by other authors and values calculated from the equation of state and correlations.

Citation

Fluid Phase Equilibria

Volume

263

Issue

1

Pub Type

Journals

Citation

Abdulagatov, I. , Polikhronidi, N. , Bruno, T. , Batyrova, R. and Stepanov, G. (2008), Measurements of the isochoric heat capacity, the critical point (Tc, pc) and vapor-liquid coexistence curve (Ts, ps) of high-purity toluene near the critical point, Fluid Phase Equilibria (Accessed July 27, 2024)