PVT, saturated liquid density and vapor-pressure measurements of main components of the biofuels at high temperatures and high pressures: Methyl palmitate

• Published in: Fuel (Guildford) 2018-04, Vol.218, p.282-294
• Main Authors: Rasulov, Suleiman M., Abdulagatov, Ilmutdin M.
• Format: Article
• Language: English
• Subjects: Atmospheric pressure; Biodiesel fuels; Biofuel; Biofuels; Coexistence; Coexistence curve; Confidence intervals; Constant-volume piezometer; Correlation analysis; Critical parameters; Density; Equations of state; Fluids; High temperature; Isochores; Measurement; Methyl palmitate; Palmitic acid; Phase transitions; Pressure; Saturated liquid density; Scaling; Soybeans; Tait-type equation of state; Temperature effects; Transition temperatures; Vapor-pressure; Vapors; Wagner-type vapor-pressure equation
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2018.01.039

[Display omitted] •Thermodynamic properties of methyl palmitate.•Vapor-pressure and coexistence curve of methyl palmitate.•Critical parameters of methyl palmitate.•Equation of state of methyl palmitate. PVT, saturated liquid density and two-phase (vapor-pressure) properties of one of the main component of the biofuel (methyl palmitate), produced from a soybean, have been measured. One-phase PVT measurements were made for ten liquid and four vapor isochores between (85.2 and 811.7) kg·m−3over the temperatures range from (300 to 443) K using a constant-volume piezometer technique. The vapor-pressures (PS,TS) of the methyl palmitate were measured in the temperature range from (300 to 501) K. The combined expanded uncertainty of the density, ρ, pressure, P, and temperature, T, measurements at 95% confidence level with a coverage factor of k = 2 is estimated to be 0.1%, (0.15–0.5)% depending on temperature and pressure ranges, and 15 mK, respectively. We have critically assessed all of the reported density data at atmospheric pressure and at high-pressures and vapor-pressures together with the present results for their internal thermodynamic consistence to carefully select primary data to fit reference correlations for ρ0(T) and vapor-pressure PS(T). The measurements were concentrated in the two-phase region to accurately determine vapor-pressures and in the immediate vicinity of the phase-transition temperatures to precisely determine the phase boundary properties (PS,TS,ρS) on the liquid + gas equilibrium curve. The liquid-gas phase transition temperatures (TS) for seven liquid isochores of (711.9, 766.8, 774.5, 782.3, 795.00, 803.40, and 811.70) kg·m−3were accurately obtained using the isochoric (P-T) break point technique. The measured values of the vapor-pressures and saturated liquid densities were fitted to Wagner-type vapor-pressure equation and complete scaling model, respectively. The values of the critical parameters (PC,TC,ρC) were estimated using vapor-pressure and liquid-gas coexistence curve data. The correlation for the density at atmospheric pressure, ρ0(T), together with the present and reported high-pressure density measurements (ρ,P,T) were used to develop two-parametric (c and B) and theoretically based Tait-type equation of state.