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2004

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Articles 121 - 131 of 131

Full-Text Articles in Chemical Engineering

Development Of First Principles Capacity Fade Model For Li-Ion Cells, P. Ramadass, Bala Haran, Parthasarathy M. Gomadam, Ralph E. White, Branko N. Popov Jan 2004

Development Of First Principles Capacity Fade Model For Li-Ion Cells, P. Ramadass, Bala Haran, Parthasarathy M. Gomadam, Ralph E. White, Branko N. Popov

Faculty Publications

A first principles-based model has been developed to simulate the capacity fade of Li-ion batteries. Incorporation of a continuous occurrence of the solvent reduction reaction during constant current and constant voltage (CC-CV) charging explains the capacity fade of the battery. The effect of parameters such as end of charge voltage and depth of discharge, the film resistance, the exchange current density, and the over voltage of the parasitic reaction on the capacity fade and battery performance were studied qualitatively. The parameters that were updated for every cycle as a result of the side reaction were state-of-charge of the electrode materials …

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Development Of Novel Method For Preparation Of Pemfc Electrodes, Hansung Kim, Branko N. Popov Jan 2004

Development Of Novel Method For Preparation Of Pemfc Electrodes, Hansung Kim, Branko N. Popov

Faculty Publications

A method based on pulse electrodeposition technique was developed for preparation of membrane electrode assemblies (MEAs). In this approach, platinum is deposited directly on the surface of the carbon electrode. The method ensures most of the platinum to be in close contact with the membrane. Using this method it is possible to increase the Pt/C ratio up to 75 wt % near the surface of the electrode resulting in a 5 µm thick catalyst layer. The MEA prepared by pulse electrodeposition exhibits a current density of 0.33 A/cm2 at 0.8 V with platinum loading of 0.25 mg of Pt/cm …

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Solvent Diffusion Model For Aging Of Lithium-Ion Battery Cells, Harry J. Ploehn, Premanand Ramadass, Ralph E. White Jan 2004

Solvent Diffusion Model For Aging Of Lithium-Ion Battery Cells, Harry J. Ploehn, Premanand Ramadass, Ralph E. White

Faculty Publications

This work presents a rigorous continuum mechanics model of solvent diffusion describing the growth of solid-electrolyte interfaces (SEIs) in Li-ion cells incorporating carbon anodes. The model assumes that a reactive solvent component diffuses through the SEI and undergoes two-electron reduction at the carbon-SEI interface. Solvent reduction produces an insoluble product, resulting in increasing SEI thickness. The model predicts that the SEI thickness increases linearly with the square root of time. Experimental data from the literature for capacity loss in two types of prototype Li-ion cells validates the solvent diffusion model. We use the model to estimate SEI thickness and extract …

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Electrodeposition Of Feconicu Quaternary System, Qiang Huang Jan 2004

Electrodeposition Of Feconicu Quaternary System, Qiang Huang

LSU Doctoral Dissertations

Electrodeposition is a cost-effective method to produce thin film materials, which have been used widely in the microelectronic industry, and is advantageous to fabricate metal deposits into recessed and curved areas. In this dissertation, FeCoNiCu quaternary alloy system was investigated, both experimentally and theoretically, for fabrication of multilayers, grating structures, and nanowires. Multilayer structures are composed of alternating ferromagnetic and nonmagnetic nanometric layers, and are of interest due to the giant magnetoresistance (GMR) property it possesses, a change in electric resistance in the presence of an external magnetic field. In addition, the compositional modulation, or the composition contrast, in multilayer …

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Laboratory Automation Education, James D. Sterling Jan 2004

Laboratory Automation Education, James D. Sterling

Business and Information Technology Faculty Research & Creative Works

No abstract provided.

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Ignition Behavior Of Live California Chaparral Leaves, Joshua D. Engstrom, Jared K. Butler, Steven G. Smith, Larry L. Baxter, Thomas H. Fletcher, David R. Weise Jan 2004

Ignition Behavior Of Live California Chaparral Leaves, Joshua D. Engstrom, Jared K. Butler, Steven G. Smith, Larry L. Baxter, Thomas H. Fletcher, David R. Weise

Faculty Publications

Current forest fire models are largely empirical correlations based on data from beds of dead vegetation. Improvement in model capabilities is sought by developing models of the combustion of live fuels. A facility was developed to determine the combustion behavior of small samples of live fuels, consisting of a flat-flame burner on a moveable platform. Qualitative and quantitative combustion data are presented for representative samples of California chaparral: manzanita (Arctostaphylos parryana); oak (Quercus berberidifolia); ceanothus (Ceanothus crassifolius), and chamise (Adenostoma fasciculatum). Times to ignition were significantly influenced by shape effects, whereas ignition temperature was more dependent on chemical composition

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Modeling The Direct Solar Conversion Of Co2 To Co And O2, Thomas H. Fletcher Jan 2004

Modeling The Direct Solar Conversion Of Co2 To Co And O2, Thomas H. Fletcher

Faculty Publications

At high temperatures (greater than 2300 K), CO2 is known to dissociate to CO and O. A prototype solar collector was previously demonstrated to achieve such high temperatures, achieving 4-6 mol % CO in the product stream from an inlet stream of pure CO2. This paper describes the results of computer modeling performed to determine the flow, temperature, and reactions occurring in the prototype device. Of particular interest are the heat-transfer and reaction mechanisms involved and how much photolysis occurs in the prototype. Predictions were performed with two different computational fluid dynamic codes (Fluent and PCGC-3). The …

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The Dependence Of The Overall Drying Time And Product Quality Of A Lyophilization Process On The Relative Position Of Vials On A Tray With Tray Sides And Without Tray Sides For Different Heat Input Control Policies, Kian Hui Gan Jan 2004

The Dependence Of The Overall Drying Time And Product Quality Of A Lyophilization Process On The Relative Position Of Vials On A Tray With Tray Sides And Without Tray Sides For Different Heat Input Control Policies, Kian Hui Gan

Masters Theses

"The dynamic behavior of the primary and secondary drying stages of the lyophilization process were studied when (a) single vials located at different positions on the tray were individually being dried, and (b) the vials on the tray are arranged in clusters of square and hexagonal arrays and all the vials on the tray are simultaneously being dried. For both cases (a) and (b), fast drying times and relatively more uniform distributions of temperature and concentration of bound water at the end of the secondary drying stage are obtained by heat input control that runs the lyophilization process close to …

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Closed Material Cycles And Organic Solvent Recovery, Tim De Jong Jan 2004

Closed Material Cycles And Organic Solvent Recovery, Tim De Jong

Theses

A survey was conducted of the pharmaceutical sector in Ireland to establish organic solvent usage, recovery and treatment practices. The eleven companies covered by the survey, which included several of the worlds largest multinational companies, consumed in the region of 122,000 tonnes of organic solvent in 2002. Approximately 53,000 tonnes was recovered on-site while 69,000 tonnes of virgin solvent was brought on-site to replace that which was lost through wastewater treatment, incineration, fugitive emissions and off-site treatment or reuse. The total quantity of virgin solvent consumed by the eleven companies accounted for 75.4 % of organic solvent imports to Ireland. …

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Ceria-Zirconia Oxide High Temperature Desulfurization Sorbent, Kwang Bok Yi Jan 2004

Ceria-Zirconia Oxide High Temperature Desulfurization Sorbent, Kwang Bok Yi

LSU Doctoral Dissertations

High temperature desulfurization of highly reducing coal-derived gases using ceria and ceria-zirconia sorbents is the primary object of this dissertation research. If H2S concentration is reduced to less than 1 ppmv the product gas may be used with fuel cells and downstream catalytic process. CeO2 is reduced to a non-stoichiometric oxide, which is superior to CeO2 in removing H2S. Moreover, ZrO2 addition to CeO2 to form a solid solution, Ce1-xZrxO2, increases the reducibility of CeO2. This should also result in improved desulfurization performance. Pure CeO2 and sorbents, both commercially available and prepared at LSU, were tested. XRD analysis indicated that …

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Chemical Production Complex Optimization, Pollution Reduction And Sustainable Development, Aimin Xu Jan 2004

Chemical Production Complex Optimization, Pollution Reduction And Sustainable Development, Aimin Xu

LSU Doctoral Dissertations

The objective of this research is to propose, develop and demonstrate chemical production complex optimization to determine the optimal configuration of chemical plants in a superstructure of possible plants. The Chemical Complex Analysis System is a new methodology that has been developed to determine the best configuration of plants in a chemical production complex based on the AIChE Total Cost Assessment (TCA) for economic, energy, environmental and sustainable costs. All new, energy-efficient, and environmentally acceptable plants using greenhouse gases that can produce potentially commercial products designed with HYSYS were integrated into the chemical complex using the System. The optimum configuration …

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