Determination of Solid-liquid-gas Equilibrium Curves for Some Fats in Presence of Carbon Dioxide

Solid-Liquid-Gas equilibrium (S-L-G) curves have been investigated for different binary systems consisting of carbon dioxide and fats in order to determine the melting point depression caused by pressurized CO2. The knowledge of the decrease of the melting points of the materials is important because different processes can be operated at reduced energetic costs. The S-L-G diagrams for binary systems containing fats and carbon dioxide have been determined experimentally using the “first melting point” method. The compounds considered were some saturated fatty acids and triglycerides that are an ester combination of fatty acids with glycerol. The interest in this class of compounds was originated starting with the idea that impregnation processes could be easier and cheaper if under a low CO2 pressure fats become liquid at temperatures close to the ambient temperature. The Peng-Robinson equation of state with two binary interaction parameters was used to predict the thermodynamic behaviour of these systems and a comparison between the P, T experimental projections and the predicted curves was performed.