MODELLING OF HIGH‐PRESSURE PHASE EQUILIBRIUM IN SYSTEMS OF INTEREST IN THE FOOD ENGINEERING FIELD USING THE PENG‐ROBINSON EQUATION OF STATE WITH TWO DIFFERENT MIXING RULES

Abstract

ABSTRACT In this work, thermodynamic models for fitting the phase equilibrium of binary systems were applied, aiming to predict the high pressure phase equilibrium of multicomponent systems of interest in the food engineering field, comparing the results generated by the models with new experimental data and with those from the literature. Two mixing rules were used with the Peng‐Robinson equation of state, one with the mixing rule of van der Waals and the other with the composition‐dependent mixing rule of Mathias et al. The systems chosen are of fundamental importance in food industries, such as the binary systems CO2‐limonene, CO2‐citral and CO2‐linalool, and the ternary systems CO2‐Limonene‐Citral and CO2‐Limonene‐Linalool, where high pressure phase equilibrium knowledge is important to extract and fractionate citrus fruit essential oils. For the CO2‐limonene system, some experimental data were also measured in this work. The results showed the high capability of the model using the composition‐dependent mixing rule to model the phase equilibrium behavior of these systems.PRACTICAL APPLICATIONSThe use of the Peng–Robinson equation of state (PR‐EOS) in description of phase equilibrium of systems at high pressure has been largely reported in the scientific literature. On the other hand, the low prediction capability of the PR‐EOS to thermodynamic properties of polar multicomponent systems has been provided with the development and application of new mixing rules. The main purpose of the present work was to study a thermodynamic model to correlate systems of interest in the food engineering field, applying the PR‐EOS to a composition‐dependent mixing rule, by comparing the results with those represented by the classical mixing rule of van Der Waals (PR‐EOS). In spite of the large interest in applying supercritical technology in obtaining highly purified extracts from food, available data from systems at high pressure related to food process, and passable to be modeled, are scarce in the literature. Therefore, the investigation of simple and effective models on the description of these systems is of great importance and is a valuable tool in the study of the high‐pressure systems behavior in the food processing field.