Equation of State for Solid Benzene Valid for Temperatures up to 470 K and Pressures up to 1800 MPa

Abstract

The thermodynamic property data for solid phase I of benzene are reviewed and utilized to develop a new fundamental equation of state (EOS) based on Helmholtz energy, following the methodology used for solid phase I of CO 2 by Trusler [J. Phys. Chem. Ref. Data 40, 043105 (2011)]. With temperature and molar volume as independent variables, the EOS is able to calculate all thermodynamic properties of solid benzene at temperatures up to 470 K and at pressures up to 1800 MPa. The model is constructed using the quasi-harmonic approximation, incorporating a Debye oscillator distribution for the vibrons, four discrete modes for the librons, and a further 30 distinct modes for the internal vibrations of the benzene molecule. An anharmonic term is used to account for inevitable deviations from the quasi-harmonic model, which are particularly important near the triple point. The new EOS is able to describe the available experimental data to a level comparable with the likely experimental uncertainties. The estimated relative standard uncertainties of the EOS are 0.2% and 1.5% for molar volume on the sublimation curve and in the compressed solid region, respectively; 8%-1% for isobaric heat capacity on the sublimation curve between 4 K and 278 K; 4% for thermal expansivity; 1% for isentropic bulk modulus; 1% for enthalpy of sublimation and melting; and 3% and 4% for the computed sublimation and melting pressures, respectively. The EOS behaves in a physically reasonable manner at temperatures approaching absolute zero and also at very high pressures.

Experimental solid–liquid equilibria and solid formation kinetics for carbon dioxide in methane for LNG processing

“…For certain compounds, like CO 2 and benzene, the pure solid fugacity can also be calculated using the Helmholtz equations of state of Trusler 37 and Xiao et al, 45 respectively, both of which are implemented in ThermoFAST. However, use of the Trusler EoS for pure solid CO 2 instead of Equation () did not improve the root mean square (RMS) deviation between the predicted and calculated SFE temperatures.…”