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The dynamic viscosity under pressure of three mixtures of pentaerythritol ester lubricants (PEs) has been measured using a rolling-ball viscometer for several temperatures with an experimental uncertainty of 3%. The first one is a multicomponent mixture of several PEs named in the present work as PEC5-C9 lubricant; the second one is a binary mixture of pentaerythritol tetra(2-ethylhexanoate), PEB8, and pentaerythritol tetraheptanoate, PEC7, with a PEB8 mole fraction of 0.6670; and the third one is another binary mixture of PEB8 and pentaerythritol tetrapentanoate, PEC5, with a PEB8 mole fraction of 0.6911. The two binary mixtures, xPEB8 + (1x)PEC7 and xPEB8 + (1x)PEC5, have been prepared with the same viscosity grade as the PEC5-C9 lubricant (VG32). A total of 1176 experimental measurements of the rolling time have been performed at pressures up to 60 MPa for the determination of 196 dynamic viscosity data points. The viscosities of these binary mixtures have been compared with the predicted values obtained by using several viscosity models (Grunberg-Nissan and Katti-Chaudhri mixing laws, self-referencing model, hard-sphere theory, and free-volume model). All methods predict dynamic viscosity values for the two binary mixtures that agree with the experimental data within an average mean deviation of 10% over the entire temperature and pressure ranges. The best predictions were found with the free-volume model, for which the average mean deviation for both mixtures is lower than 4%. Parameter values for the self-referencing model were determined from experimental viscosity data of several pure PEs. These parameters permit the estimation of viscosity values of PE lubricant of unknown composition, when a viscosity value at any temperature and pressure is available. This model predicts the viscosities of PEC5-C9 lubricant with an average deviation of 4%.

A good understanding and prediction of the phase equilibrium of the fatty acid methyl ester (FAME) + glycerol + methanol ternary system is needed to design and optimize the separation unit of the biodiesel production process. In this work, new experimental vapor−liquid−liquid data on the ternary system have been measured at temperatures between 333.15 and 473.15 K. In addition, new data have been gathered on the methanol + glycerol [vapor−liquid equilibrium (VLE)] and methanol + methyl oleate (VLE and liquid−liquid equilibrium) binary systems. A group contribution method combined with a statistical associating fluid theory equation of state (GC-PPC-SAFT) proposed earlier by our group (Group contribution method with SAFT EOS applied to vapor liquid equilibria of various hydrocarbons series Tamouza S. Passarello J.-P. Tobaly P. de Hemptinne J.-C. Tamouza S. Passarello J.-P. Tobaly P. de Hemptinne J.-C. Fluid Phase Equilib.20042222236776) and recently extended to predict VLE of heavy esters and their mixtures (Predicting VLE of heavy esters and their mixtures using GC-SAFT Nguyen Huynh D. Falaix A. Passarello J.-P. Tobaly P. de Hemptinne J.-C. Nguyen Huynh D. Falaix A. Passarello J.-P. Tobaly P. de Hemptinne J.-C. Fluid Phase Equilib.2008264184200) is here applied to model vapor liquid−liquid equilibria of methanol + glycerol + methyl oleate. The SAFT parameters for the glycerol pure component have been regressed using two association schemes (4C and 3X2B). The dispersive binary interaction parameters kij have been regressed on the binary systems. The group contribution scheme was used for predicting the ester properties.