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Full-Text Articles in Chemical Engineering

Prediction Of Vapor/Liquid Equilibrium Behavior From Quantum Mechanical Data, Marshall J. Gnap Jan 2016

Prediction Of Vapor/Liquid Equilibrium Behavior From Quantum Mechanical Data, Marshall J. Gnap

Williams Honors College, Honors Research Projects

MOSCED (Modified Separation of Cohesive Energy Density) is a particularly attractive model for activity coefficients because it offers intuitive insights into how to tune solvent-solute interactions to achieve optimized formulations. Unfortunately, only 133 compounds have been characterized with the MOSCED method. Furthermore, there is no convenient method for extending MOSCED predictions to new compounds. The hypothesis of the present research is that the surface charge density of a molecule, once normalized over the molecule surface area, provided graphically by a σ-profile from density functional theory (DFT) computations, can be used to estimate the parameters used in the MOSCED model. DFT …


Calculation Of Homogeneous Azeotropes In Reactive And Nonreactive Mixtures Using A Stochastic Optimization Approach, Adrian Bonilla-Petriciolet, Gustavo A. Iglesias-Silva, Kenneth R. Hall Jan 2009

Calculation Of Homogeneous Azeotropes In Reactive And Nonreactive Mixtures Using A Stochastic Optimization Approach, Adrian Bonilla-Petriciolet, Gustavo A. Iglesias-Silva, Kenneth R. Hall

Adrian Bonilla-Petriciolet

In this paper we introduce an alternative strategy to find homogeneous azeotropes in reactive and nonreactive mixtures which is based upon the Simulated Annealing optimization technique. This stochastic optimizationmethod is used to robustly solve a systemof non-linear equations that results fromthe equalities of the orthogonal derivatives of the Gibbs energy and the Gibbs energy of mixing in the vapor and the liquid phases. For non-reactive systems, this equation system is solved by considering conventional composition variables while for reactive cases we use the transformed composition variables proposed by Ung and Doherty. Numerical performance of our approach is illustrated using several …