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Articles 1 - 5 of 5

Full-Text Articles in Physics

Approximating A Three-Dimensional Fluidized Bed With Two-Dimensional Simulations, Mirka Deza, Francine Battaglia, Theodore J. Heindel Oct 2008

Approximating A Three-Dimensional Fluidized Bed With Two-Dimensional Simulations, Mirka Deza, Francine Battaglia, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Fluidized beds can be used to gasify biomass in the production of producer gas, a flammable gas that can replace natural gas in process heating. Modeling these reactors with computational fluid dynamics (CFD) simulations is advantageous when performing parametric studies for design and scale-up. From a computational resource point of view, two-dimensional simulations are easier to perform than three-dimensional simulations, but they may not capture the proper physics. This paper will compare two- and three-dimensional simulations in a 10.2 cm diameter fluidized bed with side air injection to determine when two-dimensional simulations are adequate to capture the bed hydrodynamics ...


Simulating Gas-Liquid Flows In An External Loop Airlift Reactor, Deify Law, Francine Battaglia, Theodore J. Heindel Oct 2008

Simulating Gas-Liquid Flows In An External Loop Airlift Reactor, Deify Law, Francine Battaglia, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

The external loop airlift reactor (ELALR) is a modified bubble column reactor that is composed of two vertical columns that are connected with two horizontal connectors. Airlift reactors are utilized in fermentation processes and are preferred over traditional bubble column reactors because they can operate over a wider range of conditions. Computational fluid dynamics (CFD) simulations can be used to enhance our understanding of the hydrodynamics within these reactors. In the present work, the gas-liquid flow dynamics in an external loop airlift reactor are simulated using CFDLib with an Eulerian-Eulerian ensemble-averaging method in two-dimensional (2D) and three-dimensional (3D) coordinate systems ...


A Validation Study For The Hydrodynamics Of Biomass In A Fluidized Bed, Mirka Deza, Francine Battaglia, Theodore J. Heindel Aug 2008

A Validation Study For The Hydrodynamics Of Biomass In A Fluidized Bed, Mirka Deza, Francine Battaglia, Theodore J. Heindel

Mechanical Engineering Conference Presentations, Papers, and Proceedings

Computational modeling of fluidized beds can be used to predict operation of biomass gasifiers after extensive validation with experimental data. The present work focused on computational simulations of a fluidized bed using a multifluid Eulerian-Eulerian model to represent the gas and solid phases as interpenetrating continua. Hydrodynamic results from the simulations were quantitatively compared with X-ray flow visualization studies of a similar bed. It was found that the Gidaspow model can accurately predict the hydrodynamics of the biomass in a fluidized bed. The coefficient of restitution of biomass was fairly high and did not affect the hydrodynamics of the bed ...


Single-Molecule Dendrimer-Hydrocarbon Interaction, Karthikeyan Pasupathy, Nicholas W. Suek, John L. Lyons, Justin Ching, Aaron Jones, Qi Lu, Monica H. Lamm, Pu Chun Ke Jan 2008

Single-Molecule Dendrimer-Hydrocarbon Interaction, Karthikeyan Pasupathy, Nicholas W. Suek, John L. Lyons, Justin Ching, Aaron Jones, Qi Lu, Monica H. Lamm, Pu Chun Ke

Chemical and Biological Engineering Publications

We report our single-molecule fluorescence microscopy and molecular dynamics simulation studies on the interaction of poly(amidoamine) dendrimer and squalane hydrocarbon in aqueous solution. Our spectrophotometry measurements indicate that this interaction increases with the pH of the solvent. Our simulations show that squalane resides primarily on the perimeter of the dendrimer at low to neutral pH, but becomes encapsulated by the dendrimer at high pH. Using single-molecule fluorescence microscopy, we have identified that the binding between PAMAM and squalane is reversible. At a pH value of 8, the approaching, binding, and characteristic times of a single fluorescently-labeled dendrimer to squalane ...


Nanoparticle Ordering Via Functionalized Block Copolymers In Solution, Rastko Sknepnek, Joshua A. Anderson, Monica H. Lamm, Jorg Schmalian, Alex Travesset Jan 2008

Nanoparticle Ordering Via Functionalized Block Copolymers In Solution, Rastko Sknepnek, Joshua A. Anderson, Monica H. Lamm, Jorg Schmalian, Alex Travesset

Chemical and Biological Engineering Publications

We consider nanoparticles and functionalized copolymers, block copolymers with attached end groups possessing a specific affinity for nanoparticles, in solution. Using molecular dynamics, we show that nanoparticles are able to direct the self-assembly of the polymer/ nanoparticle composite. We perform a detailed study for a wide range of nanoparticle sizes and concentrations. We show that the nanoparticles order in a number of distinct phases: simple cubic, layered hexagonal, hexagonal columnar, gyroid, and a novel square columnar. Our results show that nanoparticles ordered with functionalized block copolymers can provide a simple and efficient tool for assembling novel materials with nanometer scale ...