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 Walter
G. Chapman
William
W. Akers Professor in Chemical Engineering
Research Interests:
Thermodynamics
Statistical Mechanics
Molecular Simulation
Education:
B.S. (1983) Clemson University
Ph.D. (1988) Cornell University
Professor Walter G. Chapman’s Research Program
Professor Chapman’s research group uses tools such as molecular
simulation, computer visualization, statistical mechanics, and NMR
to discover how material properties and structure depend on molecular
forces. Professor Chapman’s present research program focuses
on polymer solutions and blends, associating fluids, confined fluids,
and natural gas hydrates.
Molecular Thermodynamics of Solvents, Monomers, and Polymers
Polymers with multiple functional groups have been found to possess
unique and useful optical, thermal, and mechanical properties. The
manufacture of these polymers requires knowledge of their solution
properties and phase behavior to optimize the design and operation
of reactors and separation units. Professor Chapman's group uses
molecular modeling techniques (including molecular simulation and
statistical mechanics) to relate knowledge of molecular forces to
the thermophysical properties of polymer solutions and blends. The
Statistical Associating Fluid Theory (SAFT) equation of state produced
from this research is applied by numerous polymer companies throughout
the world to model phase behavior in polymer processing.
Thermodynamics and Structure of Complex Fluids in the Interfacial
Region
Prediction of the interaction of complex fluids, (e.g., hydrogen
bonding fluids, hydrocarbons, proteins, and polymers) with adsorbing
surfaces is essential for the control of many processes of current
industrial and scientific interest. These processes include microchannel
reactors, catalysis, assembly of nano-materials, bio-sensors, and
membrane separations. Professor Chapman’s group has developed
molecular simulations and density functional theory to predict the
thermodynamic properties, structure, and surface forces of associating
and non-associating components near hydrophobic and hydrophilic
surfaces.
Mechanisms and Kinetics of Gas Hydrate Decomposition
Gas hydrates are, quite literally, self-assembled nano-structures
formed by the cooperative hydrogen bonding of water molecules to
form cages that encapsulate gas molecules. These solid crystalline
clathrate structures are significant because they trap vast amounts
of natural gas on the ocean floor (notably the Gulf coast) and in
permafrost and other geologic deposits. The amount of carbon in
gas hydrates is estimated to be more than twice the amount of carbon
in all other fossil fuel deposits. Gas hydrates have also been proposed
as potentially useful in novel gas separation processes and in transport
of natural gas. Gas hydrates are also a problem in their proclivity
to plug subsea pipelines from offshore platforms causing economic
loss and potentially unsafe conditions. To avoid hydrate plugs,
the oil and gas industry spends about 500 millions of dollars annually
on inhibitors (e.g., methanol or glycol) or as much as $48 MM to
insulate a single subsea pipeline (Exxon).
To accurately model the decomposition and formation processes and
to optimize hydrate applications requires the mechanism and dissociation
rates of hydrates as well as heat and mass transfer data. In addition,
quantifying the effect of porous media on hydrate decomposition
kinetics is essential for the production of natural gas from hydrates.
Professor Chapman’s group combines NMR and molecular simulation
with phase equilibria and kinetic studies to provide needed thermodynamic,
transport, and kinetic data for hydrate decomposition.
Asphaltene Precipitation and Deposition
The formation of asphaltene plugs in piping represent a significant
problem in oil production and refining. Asphaltenes are a collection
of polydisperse molecules consisting mostly of polynuclear aromatics
with varying proportions of aliphatic and alicyclic moieties and
small amounts of heteroatoms (oxygen, sulfur, vanadium, etc.). Problems
in recovery and refining operations associated with asphaltenes
are due primarily to their molecular size and their self-aggregation.
Hence, a better understanding of asphaltene phase behavior and deposition
requires a better understanding of how molecular size and aggregation
affect phase behavior and deposition.
A similar material to asphaltenes are polynuclear aromatics extracted
from pitch. Researchers have shown that these polynuclear aromatics
for a meso-phase that can be used to spin inexpensive, high quality
carbon fibers. Professor Chapman’s group in collaboration with
George Hirasaki is modeling the thermodynamic properties and phase
behavior of asphaltenes using the Statistical Associating Fluid
Theory (SAFT).
Modified 08/20/09
Publications
- Prasanna K. Jog and Walter G. Chapman, "Application of
Wertheim’s Thermodynamic Perturbation Theory to Dipolar Hard
Sphere Chains," Molecular Physics, 97 (1999): 307-319.
- Prasanna K. Jog, Alejandro Garcia-Cuellar and Walter G. Chapman,
"Extensions and Applications of the SAFT Equation of State
to Solvents, Monomers, and Polymers," Fluid Phase Equilibria,
158-160 (1999): 321-326.
- Alejandro Garcia-Cuellar and Walter G. Chapman, "Solvent
Effects in Model Telechelic Polymers," Molecular Physics,
96 (1999): 1063-1074.
- Keshawa P. Shukla and Walter G. Chapman, "A Two Fluid
Theory for Chain Fluid Mixtures from Thermodynamic Perturbation
Theory," Mol. Phys., 93 (1998): 287-293 .
- Chad J. Segura, Eduard V. Vakarin, Walter G. Chapman, and M.F.
Holovko, "A Comparison of Density Functional and Integral
Equation Theories versus Monte Carlo Simulations for Hard Sphere
Associating Fluids near a Hard Wall," J. Chem. Phys, 108
(1998): 4837-4848 .
- Yurko Duda, Chad J. Segura, Eduard V. Vakarin, M.F. Holovko,
and Walter G. Chapman, "Network forming fluids: Integral
equations and Monte Carlo simulations," J. Chem. Phys., 108
(1998): 9168-9176 .
- Kong S. Tian, Kenneth R. Jolls, Jasper Yen, Hector Perez, and
Walter G. Chapman, "PHASE - 3D Phase Equilibrium Visualization
Package," Software for Education, (2000).
- Walter G. Chapman, "SAFT Phase Equilibria Package,"
Engineering Software, (Since 1988).
- "SAFT Phase Equilibria Package," Software, Distributed
algorithms or code to 16 academic groups and 6 companies, (through
1999).
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