GOALI: Combining Discontinuous Molecular Dynamics and Chemical Process Simulation

University Of Akron, Akron OH

Investigators

Abstract

J. Richard Elliott, University of Akron "GOALI: Combining Discontinuous Molecular Dynamics and Chemical Process Simulation" Molecular modeling will be integrated with a chemical process simulation package to provide a complete, rigorous, and accurate framework for physical property prediction and correlation. Chemical process simulators are becoming the primary interface for industrial chemical knowledge. The PI has recently discovered that perturbation theory is much more accurate than previously appreciated, especially for polyatomic molecules. Discontinuous molecular dynamics (DMD) simulation combines with perturbation theory and the virial expansion to provide a basis for highly leveraged computational effort in all aspects of molecular modeling. An existing DMD program will run the minimal number of simulations necessary with reasonable speed on low-cost microprocessors. The resulting segmental potential models will act as molecular scale group contributions, analogous to conventional engineering group contribution models. The PI implement methods of calculating transport properties like viscosity, thermal conductivity, and diffusivity in addition to the equilibrium and coexistence properties that he has computed in the past. This research will use pre-tabulation of the essential simulation data for reference fluids, with detailed perturbation calculations to be performed with high efficiency at later times. The accuracy of this fundamental methodology will be evaluated in comparison with existing semi-empirical methods by comparison to a large database of experimental values. The PI will establish the degree to which the perturbation perspective can provide similar leveraging in the estimation of transport properties, as well as equilibrium properties. This work will be performed in collaboration with The University of Akron and the technical staff from ChemStations, Inc. The resulting product will be an internet site which clients can access for zero cost up front and relatively low hourly fees varying according to the intensity of the server side computation requested. Services provided will include molecular modeling of transport and equilibrium properties like vapor pressure, activity, water solubility, octanol partition coefficients, viscosity, and the ability to infer knowledge about one property from measurements of other properties through a common molecular model. Within the range of options will be a comprehensive collection of semi-empirical methods with estimates of the accuracy of each property. The scope of this project includes a thorough evaluation of the accuracy of semi-empirical models and the molecular based models against a database of approximately 1800 compounds. Also included will be flowsheeting and process simulation based on shortcut unit operation models. The sensitivity of the process capital and production costs to the estimated physical properties will be a menu option. The shortcut model will serve as a precursor for rigorous process simulation directly within a web-based environment. The broader impacts of the proposed research will include integrated research and education and integrated diversity. As the co-author of a leading text on Chemical Engineering Thermodynamics, the PI has already integrated results of related previous NSF support. The PI is now involved in teaching Chemical Process Design, a course that should evolve to include product design requiring extensive molecular insight. In the near term, the role of physical property estimation in traditional design can be used as a springboard for introducing many of the tools of molecular based design while directing applications to physical properties like viscosity and volatility. The predecessor to this proposal is currently supporting one female graduate student full-time and one male and one female who are alternating between teaching and research assistantships. The PI expects to maintain this balance throughout the remainder of the project.