EXPERIMENTAL STUDY OF THE DEPENDENCE OF THERMODYNAMIC PROPERTIES OF THE WATER + PROPANOL-1 BINARY SYSTEM ON ITS COMPONENT COMPOSITION OVER A WIDE RANGE OF STATE PARAMETERS

Osmanova B.K., Bazaev E.A., Bazaev A.R., Dzhapparov T.A.-G.

Institute for Geothermal Research and Renewable Energy
of the Joint Institute for High Temperatures RAS

367030, Makhachkala, Imama Shamilya st., 39a

Measurements of the (p,T-p,ρ,T)_х - dependences for 1-propanol aqueous solutions with compositions of 1-propanol (х = 0.1, 0.2, 0.3, 0.5, 0.8, 0.9 molar fractions), in two-phase, one-phase (liquid and vapor), and supercritical fluid states over temperatures ranging from 373.15 K to 673.15 K, densities between 1.5 kg/m³ and 850 kg/m³, and pressures up to 50 MPa have been carried out. The experimental values of (p,T-p,ρ,T)_x-dependencies are described by a thermal equation of state of virial form — an expansion of the compressibility factor Z = p/(RTρm) into series of reduced density and temperature powers [1].

$$Z = p/RT\rho_{m} = 1 + \sum_{i = 1}^{m}{\sum_{j = 0}^{n_{i}}a_{ij}}\omega^{i}/\tau^{j},\ and\ p = RT\rho_{m}\left\lbrack 1 + \sum_{i = 1}^{m}{\sum_{j = 0}^{n_{i}}a_{ij}}\omega^{i}/\tau^{j} \right\rbrack$$

Herein: ρ_m is the molar density (mol/m3), ω=ρ/ρ_c​and τ=T/T_c are the expressions for reduced density and reduced temperature respectively, where ρc and Tc represent critical density and critical temperature; R=8.314 J/(mol⋅K) is a universal (molar) gas constant. The average relative deviation of calculated pressure values using this equation compared to experimental data amounts to 1.2%.

Based on Equation [1] and thermodynamic relations [2], variations of the main thermodynamic properties of the studied solutions were computed. A plot illustrating the dependence of internal energy changes (U) on solution composition (x) and density (ρ) at a temperature of 623.15 K is presented in the figure.

1. Osmanova B.K., Bazaev A.R., Bazaev E.A. Experimental research of thermodynamic properties of water+ aliphatic alcohol mixtures in the wide parameters of state // Journal of Phisics: Conf.Series 1385 (2019).

2. Shpilrain E.E., Kesselman P.M. Fundamentals of Theory of Thermophysical Properties of Substances. Moscow: Energiia Publ., 1977. 248 pp.