Spreadsheet program for predicting binary system activity coefficients using UNIFAC

For many of the methods currently available to calculate activity coefficients extensive knowledge and experimental data are required. These methods usually involve extensive mathematical manipulation and data that may not be available. An alternate method based on the UNIQUAC (Universal Quasi Chemical) equation often used is the UNIFAC (UNIQAC Functional-group Activity Coefficients) method developed by Fredenslund and Jones (1975) which uses group contributions to estimate activity coefficients. This method requires no knowledge of the component's properties, and therefore can be used for components of varying complexity for which no experimental data are available.In this document it has been shown that UNIFAC is a viable method for activity coefficient determination in non-ideal, non-electrolyte binary systems. The results given by UNIFAC.XLS are comparable to results given by S. I. Sandler's UNIFAC.BAS basic language program for selected systems.UNIFAC.XLS is a Visual Basic language program in Microsoft Excel, which uses the UNIFAC equation to calculate activity coefficients of compounds, based on their functional groups, system temperature, and liquid phase mole fractions. The UNIFAC.XLS program is capable of estimating activity coefficients for binary systems in which there are five distinct functional groups per component. Ultimately these activity coefficients can be used to estimate non-ideal Gibbs energies.