abstract
The knowledge of fatty acid esters/biodiesels thermodynamic properties is crucial not only for developing optimal biodiesel production and purification processes, but also for enhancing biodiesels performance in engines. This work is intended to apply a simple but reliable theoretically based sound model, the soft-SAFT EoS, as a tool for the development, design, scale-up, and optimization of biodiesels production and purification processes. A molecular model within the soft-SAFT EoS framework is proposed for the fatty acid esters, and the Density Gradient Theory approach is coupled into soft-SAFT for the description of interfacial properties, while the Free-Volume Theory is used for the calculation of viscosities, in an integrated model. For pressures up to 150 MPa, and in the temperature range 288.15-423.15K, density, surface tension, viscosity and speed of sound data for fatty acid methyl and ethyl esters, ranging from C-8:0 to C-24:0, with up to three unsaturated bonds, are described with deviations inferior to 5%. Finally, in order to validate the predictive ability of the model to be applied in the biodiesel groundwork, the high pressure densities and viscosities for 8 biodiesels were predicted with the soft-SAFT EoS, reinforcing the validity of the approach to obtain reliable predictions for engineering purposes. (C) 2014 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
keywords
DIRECTIONAL ATTRACTIVE FORCES; LENNARD-JONES CHAINS; FATTY-ACID METHYL; DENSITY EXPERIMENTAL MEASUREMENTS; ASSOCIATING FLUID THEORY; VAPOR-LIQUID-EQUILIBRIA; HEAVY N-ALKANES; PHASE-EQUILIBRIA; IONIC LIQUIDS; ETHYL-ESTERS
subject category
Engineering
authors
Oliveira, MB; Freitas, SVD; Llovell, F; Vega, LF; Coutinho, JAP
our authors
João Manuel Costa Araújo Pereira Coutinho
Vice-Director
Mariana Belo Oliveira
Post-doc Fellowship
acknowledgements
S.V.D. Freitas acknowledges a Ph.D. Grant from Fundacao para a Ciencia e a Tecnologia through his Ph.D. grant (SFRH/BD/51476/2011), Fundacao Oriente and also financial support from the University of Aveiro. M. B. Oliveira acknowledges for her Post-Doctoral grant (SFRH/BPD/71200/2010) and F. Llovell for a TALENT contract from the Catalan Government and MATGAS. CICECO is being founded by FCT through project PEst-C/CTM/LA0011/2013. Financial support was also given by the Spanish Government under project CENIT SOST-CO2. Additional support from Carburos Metalicos, Air Products Group, and the Catalan Government was also provided (2009SGR-666).