Prof. Angelo Lucia
Department of Chemical Engineering,
URI
Date and Time: Friday, October 31, 2008 @ 2pm
Place: 126 Tyler Hall
Abstract: Waxing of petroleum or hydrocarbon fuels such as home
heating and diesel fuels is a nagging and costly problem in the
petroleum industry. Billions of dollars are spent annually on
additives to these fuels to prevent waxing or crystal formation and
on production, operational, and transportation difficulties that
arise due to wax formation. This problem is further exacerbated by
the fact that there are a large number of phase transitions that, in
turn, can lead to a variety of crystal structures. The early
literature on the structure of n-alkanes describes the molecular
conformation of n-alkanes up to about C50 as a zigzag structure with
planar chains of methylene (or CH2) units terminated by methyl
groups (CH3), where the orientation between the methyl end (or side)
groups and the planar chain is either perpendicular or tilted.
Crystal lattice structures correspond to low energy configurations
of horizontal and vertical arrangements of these zigzag molecules.
However, more recent studies using molecular dynamics show that even
single crystal structures of large n-alkanes are not planar zigzag
structures but show considerable wrapping at the ends of the
molecule.
In this work, the molecular conformation of n-alkanes is studied.
Typical fuel oils are modeled as pure n-alkanes. A multi-scale
global optimization methodology based on the combined use of a
terrain method and funneling algorithm is used to find minimum
energy molecular conformations of diesel, home heating, and residual
fuel oils as well as low energy crystal structures. The terrain
method is used to gather average gradient and average Hessian matrix
information at the small length scale while funneling is used to
generate structural changes at the large length scale that drive
iterates to a global minimum on the potential energy surface. The
funneling method uses a mixture of average and point-wise derivative
information to produce a monotonically decreasing sequence of
objective function values and to avoid getting trapped at local
minima on the potential energy surface. Computational results
clearly show that the calculated global minimum molecular
conformations are comprised of zigzag structure with considerable
wrapping at the ends of the molecule when a united-atom model of the
potential energy is used while planar zigzag conformations usually
result from an all-atom model of the potential energy.
Additionally, the terrain/funneling method can be used to identify
other low energy conformations (saddle points and local minima) and
provides insights with regard to transition dynamics. Numerical
results also clearly demonstrate that our terrain/funneling approach
is robust and computationally efficient.
Bio: Professor Angelo Lucia has a Ph.D. in Chemical Engineering from
the University of Connecticut. He is currently the Chester H. Kirk
Professor of Chemical Engineering at the University of Rhode Island,
a position he has held since 1996. Prior to that, he was a faculty
member in the Department of Chemical Engineering at Clarkson
University in Potsdam, NY for fifteen years.
Dr. Lucia's main research interests include chemical process
modeling, synthesis, design, simulation and optimization,
computational thermodynamics, applied mathematics, and numerical
methods. He has had continuous research funding from the National
Science Foundation, the Department of Energy, and a variety of
industrial sponsors with over $ 2.5 million in external funds
raised. Professor Lucia has supervised 11 MS and 10 PhD theses, 4
postdoctoral and 21 undergraduate research projects. Currently he
is supervising 1 graduate and 2 undergraduate students at URI.
Professor Lucia is the author of 82 publications (15 invited) in
refereed journals and 84 contributed and 55 invited presentations at
other universities, industry, national and international meetings.
Dr. Lucia's award include Outstanding Advisor Award, Clarkson
University, 1986; John W. Graham Faculty Research Award, 1987;
Merck, Sharp & Dohme Lecturer, 1993; Outstanding Teacher Award,
1993-94; Best Paper Award, Comput. Chem. Engng., 1996; ITC Annual
Seminar Series Lecturer, 2000, and Outstanding Researcher, URI,
2001-02. Professor Lucia is on the editorial boards of the Journal
of Global Optimization and the Journal of Thermodynamics. He has
also consulted for Control Data Corp., Amtrol, Inc., Aspen
Technology, Inc., Simulation Science, Inc., EG&G Sealol, Teknor-Apex
Co., Stanley-Bostitch, Inc., and BP.
