Comparison of Models for Supercritical Fluid Extraction of Seed and Essential Oils in Relation to the Mass-Transfer Rate

A general dimensionless model was developed for a sensitivity analysis of the supercritical extraction process of vegetable oils and essential oils. Two dimensionless parameters, Γ, a dimensionless partition coefficient, and ϑ, a dimensionless characteristic time, appeared as the most important parameters to monitor the evolution of the extraction process. Some limiting values of these two parameters within the general model yielded simpler models which are often used in the literature. The numerical solutions of both the complete model and the simpler cases were compared to assess the range of relevance of the simpler models in terms of Γ and ϑ values. These results were compared with the experimental data found in the literature to assess the correctness of the assumption used to model supercritical fluid extraction in single cases. The implications of this analysis on the development of scale-up procedures were also discussed.