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Abstract: Measurements of compressed liquid densities for 1-pentanol and for {CO2 (1)+1-pentanol (2)} system were carried out at temperatures from 313K to 363K and pressures up to 25MPa. Densities were measured for binary mixtures at 10 different compositions, x 1 =0.0816, 0.1347, 0.3624, 0.4651, 0.6054, 0.7274, 0.8067, 0.8573, 0.9216, and 0.9757. A vibrating tube densimeter was used to perform density measurements using two reference calibration fluids. The uncertainty is estimated to be better than ±0.2kg·m−3 for the experimental density measurements. For each mixture and for 1-pentanol, the experimental densities were correlated using an explicit volume equation of six parameters and an 11-parameter equation of state (EoS). Excess molar volumes were determined for the (CO2 +1-pentanol) system using 1-pentanol densities calculated from the 11-parameter EoS and CO2 densities calculated from a multiparameter reference EoS. [Copyright &y& Elsevier]

Abstract: Experimental densities were determined in liquid phase for 1-heptanol and 2-heptanol at temperatures from 313K to 363K and pressures up to 22MPa using a vibrating tube densimeter. Water and nitrogen were used as reference fluids for the calibration of the vibrating tube densimeter. The uncertainties of the experimental measurements in the whole range of reported data are estimated to be ±0.03K for temperature, ±0.008MPa for pressure, and ±0.20kg·m−3 for density. The experimental data are correlated using a short empirical equation of six parameters and the 11-parameter Benedict–Webb–Rubin–Starling equation of state (BWRS EoS) using a least square optimization. Statistical values to evaluate the different correlations are reported. Published density data of 1-heptanol are compared with values calculated with the 6-parameter equation using the parameters obtained in this work. The experimental data determined here are also compared with an available correlation for 1-heptanol. Densities of 2-heptanol at high pressure were not found in the literature and the data reported here represent the first set of data reported in the literature. Isothermal compressibilities and isobaric thermal expansivity are calculated using the 6-parameter equation for both alcohols within uncertainties estimated to be ±0.025Gpa−1 and ±4×10−7 K−1, respectively. [Copyright &y& Elsevier]

Abstract: (p, ρ, T) properties were determined in liquid phase for 1-butanol and 2-butanol at temperatures from 313K to 363K and pressures up to 25MPa using a vibrating tube densimeter. The uncertainty is estimated to be lower than ±0.2kg·m−3 for the experimental densities. Nitrogen and water were used as reference fluids for the calibration of the vibrating tube densimeter. Experimental densities of 1-butanol and 2-butanol were correlated with a short empirical equation and the 11-parameter Benedict–Webb–Rubin–Starling equation of state (BWRS EoS) using a least square optimization. Statistical values to evaluate the different correlations were reported. Published densities of 1-butanol and 2-butanol are compared with values calculated with the BWRS EoS using the parameters obtained in this work. The experimental data determined here are also compared with available correlations for 1-butanol and 2-butanol. [Copyright &y& Elsevier]

[Display omitted] • Liquid to solid phase transition of biodiesel was detected via vibrating tube densimeter technique for the first time. • The established procedure for solidification detection could be extended for other amorphous materials. • Solidification of biodiesel was detected by upwards pressurization. • Liquid densities for waste beef tallow FAMEs, FAEEs and FABEs are reported from 286 to 393 K, and pressures up to 137 MPa. • FAMEs had the highest density, while the lowest density was observed for FABEs. Phase behavior and thermophysical properties of biodiesel at high pressure and high temperature are limited in the literature. These are useful to develop models and to understand their behavior having in mind the use of biodiesel in engines. Liquid to solid phase transitions, by using a vibrating tube densimeter, along with densities of three beef tallow fatty acid alkyl esters were studied in this work. Measurements of the oscillating period for each biofuel were carried out in a modular array constituted by two vibrating tube densimeters coupled in series and connected to a single loading cell. The oscillating period was converted to density by the forced path mechanical calibration (FPMC) method. Experimental liquid density sets for three beef tallow biodiesel samples based on fatty acid alkyl esters (FAAEs) are reported for the first time for pressures up to 137 MPa. These biofuels, named fatty acid methyl esters (FAMEs), fatty acid ethyl esters (FAEEs) and fatty acid butyl esters (FABEs), were measured in the temperature range of 286–393 K. The detection procedure for the beginning of the high-pressure solidification was focused on the beef tallow FABEs sample based upon its lower cloud point (CP FABEs = 281.15 K) in comparison with the reported property for the other esters (CP FAEEs = 289.15 K, CP FAMEs = 291 K) with the same feedstock; therefore, the conditions for the metastable liquid to solid phase transition associated to the effect of high pressure was detailed for waste beef tallow butyl ester biodiesel by performing step-by-step compressions in the interval of 286.20–298.13 K and with the help of the vibrating tube densimeters. FABEs had the lower density in contrast with FAEEs and FAMEs, this one being the denser biofuel. Modeling of liquid density data was performed by the perturbed-chain statistical associating fluid theory (PC-SAFT) Equation of State and the Tammann-Tait equation with maximum absolute average deviations of 0.15 % and 0.05 %, respectively. Both models were applied for correlating the thermodynamic derived properties of the fluid phase: isobaric thermal expansivity and isothermal compressibility. [ABSTRACT FROM AUTHOR]