Methods and Materials PROPERTY PACKAGES (UNIFAC) The UNIFAC (Universal quasi-chemical Functional Group ActivityCoefficients) method is a semi-empirical system for the prediction ofnon-electrolyte activity in non-ideal mixtures. It uses the functional groups,which presents on the molecules makes up the liquid mixture to calculateactivity coefficients. Activity of the solutionscan be obtained by utilizing interactions for each of the functional groupspresent on the molecules including binary interaction coefficients. We use this method, as it requires no experimental data for the particularmixture of interest. Here, the mixture is “ACETONE/PHENOL” mixture. THERMODYNAMICS OF THE MODEL Separation operations are major problems in part of chemical engineeringdesign.
Many of these are diffusion operations which are phase-contacting type,distillation, absorption, and extraction are the most common operations. Weneed quantitative information on phase equilibrium in multi-component mixturessuch as temperature, pressure, and compositions. These parameters are rarelyavailable to acquire the desired experimental equilibrium data in a particulardesign. Therefore, it is necessary to estimate and interpolate existing data todetermine the desired equilibrium from required conditions. UNIFAC model can beused for this kind of purposes. The UNIFAC group contribution method is areliable and fast method for predicting liquid phase activity coefficients innon-electrolyte, non-polymeric mixtures at low temperatures, pressures tomoderate temperatures, pressures between 300 K and 425K.
This method widelyused in practical chemical engineering applications mostly in phase equilibriumcalculations where little or no relevant experimental information is available. Advantages· Flexibility, as UNIFAC method has awell founded basis for estimation and establishing group sizes and shapes.· Simplicity, because UNIFAC parametersare nearly independent of temperature.
· Largerange of applicability. Disadvantages· All components must be condensable.· Doesn’tapply to mixtures of polymers.