Equations of state

The goal of this project is to develop an equation of state that is based on a consistent theoretical framework rooted in the statistical mechanics for all the phases, solid, liquid, and vapor. This is analogous to using a single equation of state for calculating vapor-liquid equilibria, as opposed to using an equation of state for the vapor phase and an activity coefficient model for the liquid phase. We believe that having a consistent thermodynamic framework for all phases will lead to a more predictive and hence less data-dependent model.

Our other project in this area is the development of more predictive equations of state for complex systems, for example, polymers with complex architecture, associating macromolecules, and electrolyte solutions. Our approach is based on the Statistical Associating Fluid Theory (SAFT).

Macromolecular phase equilibria

The goal of this project is to understand and model phase equilibria of complex polymeric systems, including solutions in supercritical solvents. The challenges include understanding the effects of polymer microstructure, polydispersity, crystallizability, and chain-branch-density on phase equilibria. Such understanding is needed to develop new polymer technologies, for example, polymer separations, particle formation, fouling prevention, and environmentally benign processing. Our current research deals with polymers having complex architecture, such as graft and block copolymers, which have both bulk phase separation and microphase separation in compressible fluids.

Thermodynamic characterization of CO2-containing reservoir fluids

The goal of this project is to characterize thermophysical properties and phase behavior of CO2-containing reservoir fluids, including the experimental characterization and molecular modeling of fluid-phase and solid-phase behavior of hydrocarbon fractions in the presence of injected CO2 and brine. These properties and phase behavior are key input to any reservoir simulation, which will heavily influence the design of oil recovery strategies.

Minimum Miscibility Pressure prediction based on molecular model

The goal of this project is to develop a method that can be used to predict Minimum Miscibility Pressure (MMP) for CO2-containing reservoir fluids, which is one of the key design parameters for oil recovery. This project is a synthesis of experiment and molecular thermodynamic modeling.

Besides the phase composition, density, and viscosity predictions, the prediction of MMP is especially important. MMP is the pressure required for multi-contact miscible displacement. When the reservoir pressure is near or above the MMP, CO2 can displace oil quite efficiently in the invaded zones of the reservoir.

The prediction of MMP, which depends on the reservoir temperature and the oil composition, is also one of the reservoir technology challenges. The prediction still relies on empirical approaches, which always require experimental data for different reservoir fluid compositions. A few theoretical approaches have been developed, but none of them can be used to predict MMP for complex systems, such as reservoir fluids containing CO2 and brine. The approach proposed for this project is to use a molecular-based equation of state referred to as Statistical Associating Fluid Theory (SAFT) coupled with a thermodynamic calculation procedure. A slim tube experiment will be conducted to support the development of the model.

CO2 solubility in ionic liquids

The goal of this project is to develop a thermodynamic approximation that captures the effects of cations, anions, and substituents on the properties of ionic liquids, especially those pertinent to CO2 solubility. Such an approximation is needed both to guide the synthesis of new ionic liquids and to scale up a future absorption process.

Publications

1. Adidharma, H.; Radosz, M. Prototype of an Engineering Equation of State for Heterosegmented Polymers. Ind. Eng. Chem. Res., 1998, 37, 4453-4462.
2. Adidharma, H.; Radosz, M. Square-well SAFT equation of state for homopolymeric and heteropolymeric fluids. Fluid Phase Equilib., 1999, 158-160, 165-174.
3. Adidharma, H.; Radosz, M. A study of square-well statistical associating fluid theory approximations. Fluid Phase Equilib., 1999, 161, 1-20.
4. Kinzl, M.; Luft, G.; Adidharma, H.; Radosz, M. SAFT Modeling of Inert-Gas Effects on the Cloud-Point Pressures in Ethylene Copolymerization Systems: Poly(ethylene-co-vinyl acetate)+Vinyl Acetate+Ethylene and Poly(ethylene-co-hexene-1)+Hexene-1+Ethylene with Carbon Dioxide, Nitrogen, or n-Butane. Ind. Eng. Chem. Res., 2000, 39, 541-546.
5. Chan, K. C.; Adidharma, H.; Radosz, M. Fluid-Liquid and Fluid-Solid Transitions of Poly(ethylene-co-octene-1) in Sub- and Supercritical Propane Solutions. Ind. Eng. Chem. Res., 2000, 39, 3069-3075.
6. Chan, K. C.; Adidharma, H.; Radosz, M. Fluid-Liquid Transitions of Poly(ethylene-co-octene-1) in Supercritical Ethylene Solutions. Ind. Eng. Chem. Res., 2000, 39, 4370-4375.
7. Kiselev, S.B.; Ely, J.F.; Adidharma, H.; Radosz, M. A Crossover Equation of State for Associating Fluids, Fluid Phase Equilib., 2001, 183-184, 53-64.
8. Adidharma, H.; Radosz, M. SAFT1 for Associating Fluids: Alkanols. J. Phys. Chem. B, 2001, 105, 9822-9827.
9. Adidharma, H.; Radosz, M. Inclusion and Exclusion Approximations of Copolymer Solids Applied to Calculation Solid-Liquid Transitions. Ind. Eng. Chem. Res., 2002, 41, 1774-1779.
10. Adidharma, H.; Tan, S.P.; Radosz, M. Prototype of an LJ-solid Equation of State Applied to Argon, Krypton, and Methane. Molec. Phys., 2002, 100, 2559-2569.
11. Tan, S.P.; Adidharma, H.; Radosz, M. Weeks-Chandler-Andersen Model for Solid-Liquid Equilibria in Lennard-Jones Systems. J. Phys. Chem. B, 2002, 106, 7878-7881.
12. Adidharma, H.; Radosz, M.; Luszczyk, M. Retrograde Melting Behavior in Polyolefin+Solvent+Antisolvent Solutions. AIChE J., 2003, 49, 1044-1049.
13. Tan, S.P.; Adidharma, H.; Radosz, M. Generalized Procedure for Estimating the Fractions of Nonbonded Associating Molecules and Their Derivatives in Thermodynamic Perturbation Theory. Ind. Eng. Chem. Res., 2004, 43, 203-208.
14. Tan, S.P.; Adidharma, H.; Radosz, M. Reply to Comments on "Generalized Procedure for Estimating the Fractions of Nonbonded Associating Molecules and Their Derivatives in Thermodynamics Perturbation Theory". Ind. Eng. Chem. Res., 2004, 43, 6263-6264.
15. Adidharma, H.; Radosz, M. The LJ-Solid Equation of State Extended to Thermal Properties, Chain Molecules, and Mixtures. Ind. Eng. Chem. Res., 2004, 43, 6890-6897.
16. Tan, S.P.; Meng, D.; Plancher, H., Adidharma, H.; Radosz, M. Cloud Points for Polystyrene in Propane and Poly(4-methyl styrene) in Propane. Fluid Phase Equilib., 2004, 226, 189-194.
17. Tan, S.P.; Adidharma, H.; Radosz, M. Statistical Associating Fluid Theory Coupled with Restricted Primitive Model To Represent Aqueous Strong Electrolytes. Ind. Eng. Chem. Res., 2005, 44, 4442-4452.
18. Ji, X.; Tan, S.P.; Adidharma, H.; Radosz, M. Statistical Associating Fluid Theory Coupled with Restricted Primitive Model to Represent Aqueous Strong Electrolytes: Multiple-salt Solutions. Ind. Eng. Chem. Res., 2005, in press.
19. Ji, X.; Tan, S.P.; Adidharma, H.; Radosz, M. The SAFT1-RPM Approximation Extended to Phase Equilibria and Densities of CO2-H2O and CO2-H2O-NaCl Systems. Ind. Eng. Chem. Res., 2005, accepted.
20. Tan, S.P.; Adidharma, H.; Towler, B.F.; Radosz, M. Friction Theory and Free-Volume Theory Coupled with Statistical Associating Fluid Theory for Estimating the Viscosity of Pure n-Alkanes. Ind. Eng. Chem. Res., 2005, submitted.