Modeling systems relevant to the biodiesel production using the CPA equation of state. Part 2. Systems with supercritical CO2

Abstract

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Costa Tsonopoulos – his legacy and some personal reflections on cubic equations of state and beyond

“…The first case study comes from the modeling of systems of relevance to biodiesel production, an area where both we [33,34] and others [35][36][37][38][39] have previously published calculations with CPA. Next results for multicomponent systems that contain fatty acid esters and alcohols, glycerol and/or water will be presented.…”

“…All pure fluid and binary parameters were adopted from literature, as shown in Tables A1-A4 of the Appendix A. Water, alcohols and glycerol were modeled as self-associating compounds [33,34,36] and, consequently, cross association was considered between such molecules in their mixtures. Furthermore, in all cases cross association was assumed between esters and alcohols, glycerol or water.…”

“…Consequently, the model was then applied to predict the phase behavior of the ternary systems. For some binary sub-systems, for which experimental data do not exist, the binary parameters were predicted using previously presented correlations (of binary parameters against the ester's molecular weight) [33,34]. The deviations of model predictions from experimental data are presented in Table 1 and one example is illustrated in Figure 1.…”

“…Table A3. Binary parameters used for the prediction of the water solubility in biodiesel samples of Table A4 (Some values were predicted using the correlations of Tsivintzelis et al, [33,34]…”

Modeling Binary and Multicomponent Systems Containing Supercritical CO2 with Polyethylene Glycols and Compounds Relevant to the Biodiesel Production

“…Modeling the thermodynamic properties of such mixtures is rather demanding, mainly due to the non-ideal behavior of some systems (i.e., mixtures with organic acids and other hydrogen-bonding or high-molecular-weight compounds) and the use of high pressures [6][7][8]. In such systems, the hydrogen-bonding behavior significantly affects the phase behavior and other thermodynamic properties, especially the vaporization enthalpies and the heats of mixing [6][7][8]. Thus, explicitly accounting for various self-and cross-association interactions is the safest way for modeling using equations of state.…”