Fluid Phase Equilibria 362 (2014) 318–327 Contents lists available at ScienceDirect Fluid Phase Equilibria jou rn al h om epage: www.elsevier.com/locate/fluid Data, analysis and modeling of physical properties for process design of systems involving lipids Larissa P. Cunico a , Roberta Ceriani b , Bent Sarup c , John P. O’Connell d , Rafiqul Gani a,∗ a Computer Aided Process-Product Engineering Center (CAPEC), Department of Chemical and Biochemical Engineering, Technical University of Denmark, DK-2800, Kongens Lyngby, Denmark b Faculty of Chemical Engineering, State University of Campinas, Avenida Albert Einstein 500, Cidade Universitária Zeferino Vaz, 13083-852 Campinas, Sao Paulo, Brazil c Vegetable Oil Technology Business Unit, Alfa Laval Copenhagen A/S, Maskinvej 5, DK-2860 Soeborg, Denmark d Department of Chemical Engineering, University of Virginia, Charlottesville, VA 22901, USA a r t i c l e i n f o Article history: Received 29 July 2013 Received in revised form 11 October 2013 Accepted 16 October 2013 Available online 26 October 2013 Keywords: Property modeling Lipids Vapor–liquid equilibrium database Solid–liquid equilibrium database Activity coefficient models a b s t r a c t Pure component and mixture properties are necessary for synthesis, design, and analysis of processes for the production of edible oils, fats, biodiesel, and other lipids. The lack of measured data for these systems makes it necessary to develop reliable predictive models based on limited data. We have systematically collected data for vapor–liquid equilibrium (VLE), solid–liquid equilibrium (SLE) and related pure com- ponent properties involving lipid systems as a first step toward developing relevant property models. The established consistency tests to evaluate the VLE data of lipid systems as well as lipid properties are briefly reviewed. For SLE systems, where consistency tests based on the Gibbs–Duhem equation cannot be implemented, a consistency test has been developed. It involves limiting conditions and regression of the parameters for a new thermodynamic model that combines solute activity coefficients in the liq- uid phase at infinite dilution and a theoretically based term to account for the non-ideality in dilute solutions. This model gives noticeably better descriptions of experimental data in lipid systems than do traditional models. Examination of various objective functions for regressing model parameters showed that some variation of parameter values and differences in accuracy can be found, though they are not large. Some original UNIFAC group contribution parameters for lipids have been revised by fitting to the lipid database. © 2013 Elsevier B.V. All rights reserved. 1. Introduction The world’s production of oils and fats has grown from 79.2 mil- lion tons in 1990 to nearly 176 million tons in 2011 [1]. Most of the substances involved are lipids, which are organic components insoluble in polar solvents (such water), and soluble in organic solvents (such as chloroform and acetone) and alcohol. Lipids are molecules that totally or in part originate from carbanion-based condensations of thioesters, as fatty acids, and/or originate by carbocation-based condensations of isoprene units, as sterols [2]. This work considers the main classes of lipids present in edible oils and biodiesel production systems, namely, fatty acids, esters (methyl and ethyl), triacylglycerols (TAGS), diacylglycerols (DAGS), monocylglycerols (MAGS), phospholipids, tocopherols, squalenes, among others (see Table 1 for examples of lipids considered in this work). This growth in the production and consumption of oils and ∗ Corresponding author. Tel.: +45 45252882; fax: +45 45932906. E-mail address: rag@kt.dtu.dk (R. Gani). fats challenges the lipid processing industry to design and develop better products and processes. Lipids are often not tabulated in common property databases and their polyfunctional structure requires careful model analy- sis. The availability and reliability of data and modeling of the properties and phase equilibria for pure lipids and their mixtures are summarized in the present work. The collected SLE data of lipids (CAPEC Lipids Mixtures Database) provides saturation com- positions of solid components in solution at specific temperatures. Finding the solid structure and/or considering its effect on the satu- ration composition of the liquid is not an objective of this particular work. Rather, because measurement uncertainties or quality esti- mates are unavailable for many literature experimental data, we focus on the analysis of data quality for systems where the solid is probably well characterized. In this work, VLE data have been evaluated following the consis- tency tests recommended by NIST [22], based on the Gibbs–Duhem equation, pure component limits, and accuracy in regressing excess Gibbs Energy models. Further, we have considered options for objective functions in parameter regression, including least- squares and maximum likelihood estimation, especially because 0378-3812/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.fluid.2013.10.040