A new free volume model for dynamic viscosity and density of dense fluids versus pressure and temperature

cited By 63International audienceThis article presents a model based on the free volume concept, which describes the variations of dynamic viscosity and density versus temperature and pressure for the dense fluids (density > 200 kg · m-3). This model involves 6 constants for each pure compound: 3 for viscosity and 4 for density (1 constant is common to both quantities). Moreover if the viscosity and the density are known at a pressure and temperature of reference, it is sufficient to use 4 constants per pure compound. If the density is assumed to be known the model fits the viscosity data with an average absolute deviation of 3.8% for 3297 data corresponding to 41 very different pure compounds (alkanes, alkylbenzenes, cycloalkanes, alcohols, carbon dioxide, refrigerants). If the pressure is lower than 110 MPa the average absolute deviation is 2.8% for viscosity (2977 points). The model gives also good results for water (3.6%). If the density is unknown, for pressures lower than 110 MPa the model represents viscosity with an average absolute deviation of 3.5% and for the density the average absolute deviation is 1.5%

Viscosity and Excess Volume at High Pressures in Associative Binaries

cited By 37International audienceThe dynamic viscosity η and the density ρ of three pure substances (water, 2-propanol, diacetone alcohol) and the three associated binaries were measured versus temperature T (303.15, 323.15, and 343.15 K) and pressure P. For the binary systems the mole fractions x of each component were, successively, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, and 1. For viscosity the experimental results (P ≤ 100 MPa) represent a total of 540 data points: 54 for the pure substances and 486 for the binary mixtures (x ≠ 0 and x ≠ 1). For density the experimental results (P ≤ 70 MPa) represent 1260 values: 126 for the pure substances and 1134 for the binary mixtures (x ≠ 0 and x ≠ 1). The mixtures with water are highly associative and the curves for the variation of η with composition exhibit a maxima. The variations of the excess activation energy of viscous flow ΔGE are discussed. Moreover, the measurements of ρ are sufficiently accurate to determine the excess volumes VE versus pressure, temperature, and composition

Viscosity and density at high pressures in an associative ternary

cited By 17International audienceThe dynamic viscosity η and the density ρ of the associative ternary mixture water + diacetone alcohol + 2-propanol have been measured as a function of temperature T (303.15, 323.15, and 343.15 K) and pressure P (≤ 100 MPa). The experimental results correspond to 698 values of η and ρ. With reference to the 54 values previously published on pure substances and 486 values for three corresponding binaries, the system is globally described by 1188 experimental values for various values of P, T and composition. The results for η are discussed in terms of excess activation energy of viscous flow