PVT and Thermal-Pressure Coefficient Measurements and Derived Thermodynamic Properties of 2-Propanol in the Critical and Supercritical Regions

Abstract

PVT properties and the thermal-pressure coefficient, $$\gamma_{\text{V}} = \left( {\partial P/\partial T} \right)_{\text{V}}$$ , of 2-propanol have been simultaneously measured in the near- and supercritical regions using high-temperature and high-pressure nearly constant-volume piezo-calorimeter. Measurements were made along 9 liquid and 3 vapor isochores between (234.3 and 697.69) kg·m−3 and at temperatures from (317.17 to 522.36) K at pressures up to 6.05 MPa. For each measured isochore ( $$\rho$$ ), the values of phase transition temperature ( $$T_{S}$$ ) and pressure ( $$P_{S}$$ ) at the liquid–gas phase equilibrium curve have been determined using the isochoric $$P - T$$ break point and thermal-pressure coefficient abruptness techniques. The measured saturated liquid ( $$\rho^{\prime}_{S}$$ ) and vapor ( $$\rho^{\prime\prime}_{S}$$ ) densities near the critical point and thermal-pressure coefficient abruptness disappearance were used to estimate the values of the critical parameters ( $$T_{C}$$ = 508.72 K, $$P_{C}$$ = 4.840 MPa, and $$\rho_{C}$$ = 268.82 kg·m−3) of 2-propanol. The expanded uncertainty of the pressure ( $$P$$ ), density ( $$\rho$$ ), and thermal-pressure coefficient ( $$\gamma_{\text{V}}$$ ) measurements at the 95 % confidence level with a coverage factor of k = 2 are estimated to be 0.05 %, 0.16 %, and 1.5 %, respectively. Scaling-type critical anomaly of the asymptotic behavior of thermal-pressure coefficient in the immediate vicinity of the critical point was experimentally observed. The measured pressures ( $$PVT$$ ) and thermal-pressure coefficients ( $$\gamma_{\text{V}} VT$$ ) have been used to calculate of the other key thermodynamic properties such as internal pressure ( $$P_{\text{int}}$$ ), enthalpy ( $$\Delta H_{vap}$$ ) and entropy ( $$\Delta S_{vap}$$ ) of vaporization, saturation ( $$C_{\text{sat}}$$ ), isobaric ( $$C_{\text{P}}$$ ), and isochoric ( $$C_{\text{V}}$$ ) heat capacities.