Engineering Commons^™

Prediction Of Pressure Drop And Liquid Holdup In High-Pressure Trickle-Bed Reactors, M. (Muthanna) H. Al-Dahhan, M. R. Khadilkar, Y. Wu, M. P. Duduković

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Holub Et Al. (1992, 1993) Phenomenological Model for Pressure Drop and Liquid Holdup in Trickle Flow Regime at Atmospheric Pressure Was Noted by Al-Dahhan and Duduković (1994) to Systematically Underpredict Pressure Drop at High Pressure and High Gas Flow Rates. in This Study, the Holub Et Al. (1992, 1993) Model Has Been Extended to Account for the Interaction between the Gas and Liquid Phases by Incorporating the Velocity and the Shear Slip Factors between the Phases. as a Result, the Prediction of Pressure Drop at the Operating Conditions of Industrial Interest (High Pressure) Has Been Improved Noticeably Without Any …

Proton Diffusion In Nickel Hydroxide: Prediction Of Active Material Utilization, Sathya Motupally, Christopher C. Streinz, John W. Weidner

Faculty Publications

Galvanostatic charge and discharge experiments reveal that the active material in nickel electrodes cannot be fully accessed at high currents or for thick films. It has been proposed that the utilization of the active material is controlled by the diffusion rate of protons through the film. This hypothesis is supported by the good agreement between mathematical simulations of material utilization and experimental data over a range of charge and discharge currents and film thicknesses. Furthermore, the fraction of material utilized is larger on charge than on discharge. The asymmetry on charge and discharge is due to a diffusion coefficient that …

Chromium Oxides And Lithiated Chromium Oxides. Promising Cathode Materials For Secondary Lithium Batteries, Pankaj Arora, Dong Zhang, Branko N. Popov, Ralph E. White

Faculty Publications

Chromium oxides and lithiated chromium oxides were synthesized by thermal decomposition of chromium trioxide (CrO₃) at high temperatures and oxygen pressures. Synthesis temperature and pressure markedly affect the performance of these cathode materials. Higher pressures lead to a higher O/Cr ratio and fewer impurities in the final product. These materials are stable intercalation hosts for lithium, and exhibit a higher capacity than any of the prominent positive electrodes used in secondary lithium batteries. m-CrO_x has a capacity of 255 mAh/g, while m-LiCrO_x has a capacity of 210 mAh/g, during the first discharge. The average …

Evaluation Of Ch4/Nox Reduced Mechanisms Used For Modeling Lean Premixed Turbulent Combustion Of Natural Gas, Hemant P. Mallampalli, Thomas H. Fletcher, J Y. Chen

Faculty Publications

This study has identified useful reduced kinetic schemes that can be used in comprehensive multi-dimensional gas-turbine combustor models. Reduced mechanisms lessen computational cost and possess the capability to accurately predict the overall flame structure, including gas temperatures and key intermediate species such as CH₄, CO and NO_x. In this study, four-new global mechanisms with 5, 6, 7, and 9 steps based on the full GRI 2.11 mechanism, were developed and evaluated for their potential to model natural-gas chemistry (including NO_x chemistry) in gas turbine combustors. These new reduced mechanisms were optimized to model the high …

Nitrogen Transformations In Coal During Pyrolysis, Simon R. Kelemen, Martin L. Gorbaty, P J. Kwiatek, Thomas H. Fletcher, Mathew Watt, Mark S. Solum, Ronald J. Pugmire

Faculty Publications

X-ray photoelectron spectroscopy (XPS) was used to identify and quantify the changes in organically bound nitrogen forms present in the tars and chars of coals after pyrolysis. For fresh coal, pyrrolic nitrogen is the most abundant form of organically bound nitrogen, followed by pyridinic, quaternary, and amino types. Some of the quaternary nitrogen species initially present in coal are lost upon mild pyrolysis, prior to hydrocarbon devolatilization. These quaternary species are attributed to pyridinic or basic nitrogen species associated with hydroxyl groups from carboxylic acids or phenols. A portion of the quaternary nitrogen species is lost at the very earliest …

Methods For Predicting Shale Durability In The Field, Paul Michael Santi, Jerry D. Higgins

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Durability of shales and other weak rock is an important parameter describing the material's susceptibility to breakdown upon exposure to water or during construction work. While laboratory methods have been developed to measure durability, no correlations between laboratory results and simple field tests have been determined. The results of this study show that certain field parameters can predict slake durability with acceptable accuracy. The recommended field tests, in order of desirability, are slake index, jar slake, hammer rebound, and NGI "Q" value. Single variable and multiple variable linear regression equations are given, including equations conservatively modified so that 95% of …

Electrochemical Investigations Of Cobalt-Doped Limn2O4 As Cathode Material For Lithium-Ion Batteries, P. Arora, Branko Popov, Ralph E. White

Faculty Publications

A wide range (y = 0.05–0.33) of Co-doped LiCo_yMn_2–yO₄ spinels were synthesized and electrochemically characterized. These Co-doped spinels showed improved specific capacity and capacity retention over pure spinels. Electrochemical impedance spectroscopy and the linear polarization resistance technique were used to determine the transport and electrochemical kinetic parameters of Co-doped spinels. The presence of Co in the spinel inhibits the passivation process occurring on the surface of the cathode. Also, Co increases the exchange current density and facilitates the charge-transfer reaction of the active material. The lower self-discharge observed for Co-doped spinels was attributed …

Characterization Of Hydrogen Permeation Through Zinc-Nickel Alloys Under Corroding Conditions: Mathematical Model And Experimental Study, M. Ramasubramanian, Branko N. Popov, Ralph E. White

Faculty Publications

A mathematical model was developed for the characterization of hydrogen permeation into metals and alloys under corroding conditions. The model requires a knowledge of the corrosion rate of the given metal or alloy in solutions of various H⁺ concentrations. It provides quantitative values of rate constants of the hydrogen discharge, recombination, and adsorption reactions. This model can serve as a diagnostic criterion for determining the effectiveness of various metals and alloys as hydrogen permeation inhibitors and can be used for evaluation of hydrogen entry inhibition efficiency. Experiments were carried out to study the effectiveness of thin layers of electrodeposited …

Characterization Of Sol-Gel-Derived Cobalt Oxide Xerogels As Electrochemical Capacitors, Chuan Lin, James A. Ritter, Branko N. Popov

Faculty Publications

Very fine cobalt oxide xerogel powders were prepared using a unique solution chemistry associated with the sol-gel process. The effect of thermal treatment on the surface area, pore volume, crystallinity, particle structure, and corresponding electrochemical properties of the resulting xerogels was investigated and found to have significant effects on all of these properties. The xerogel remained amorphous as Co(OH)₂ up to 160°C, and exhibited maxima in both the surface area and pore volume at this temperature. With an increase in the temperature above 200°C, both the surface area and pore volume decreased sharply, because the amorphous Co(OH)₂ decomposed …

Studies On Electroless Cobalt Coatings For Microencapsulation Of Hydrogen Storage Alloys, Bala S. Haran, Branko N. Popov, Ralph E. White

Faculty Publications

LaNi_4.27Sn_0.24 alloy was microencapsulated with cobalt by electroless deposition from an alkaline hypophosphite bath. Discharge curves of the encapsulated alloy indicate an additional contribution to the capacity arising from the cobalt on the surface. Studies on cobalt thin films reveal the presence of adsorbed hydrogen in cobalt. The amount of hydrogen adsorbed was observed to increase with time of cathodic polarization and to reach a maximum. Polarization techniques have been used to characterize the cobalt-plated alloy as a function of state of charge. The equilibrium potential of the microencapsulated electrode at low hydrogen concentration is determined by …

Theoretical Analysis Of Metal Hydride Electrodes: Studies On Equilibrium Potential And Exchange Current Density, Bala S. Haran, Branko N. Popov, Ralph E. White

Faculty Publications

A theoretical model for the metal hydride electrode has been developed assuming that hydrogen diffusion in the alloy and charge-transfer at the surface control the discharge process. Theoretical equations for the dependence of equilibrium potential and exchange current density on the surface hydrogen concentration have been derived. These parameters have been used to correlate experimental data with the theoretical electrode discharge model. Analysis of both the experimental and theoretical discharge curves reveals a potential plateau determined by the magnitude of the interactions between the hydrogen in the alloy and the unhydrided metal. Neglecting these hydrogen-metal site interactions results in simulations …

A Nonisothermal Nickel‐Hydrogen Cell Model, Pauline De Vidts, Javier Delgado, B. Wu, D. M. See, K. Kosanovich, Ralph E. White

Faculty Publications

No abstract provided.

The Role Of Oxygen At The Second Discharge Plateau Of Nickel Hydroxide, Sathya Motupally, Mukul Jain, Venkat Srinivasan, John W. Weidner

Faculty Publications

It was shown that the appearance of a secondary discharge plateau approximately 400 mV below the primary plateau can result from the reduction of oxygen. During the galvanostatic discharge of planar nickel-hydroxide films at room temperature and in 3 weight percent KOH solutions, the second discharge plateau was observed only in the presence of dissolved oxygen in the electrolyte. When the solution was deoxygenated, no residual capacity could be extracted from the films even at low discharge rates or from overcharged films. In addition, the duration of the second plateau is inversely proportional to the square of the discharge current, …

Steady-State Modeling Of A Parallel-Plate Electrochemical Fluorination Reactor, Kamal Jha, Gerald L. Bauer, John W. Weidner

Faculty Publications

A steady-state mathematical model of a parallel-plate reactor was developed for studying the electrochemical fluorination of organic compounds dissolved in anhydrous hydrogen fluoride. The model incorporates two-phase flow with differential material, energy, and pressure balances. Profiles of temperature, pressure, vapor volume fraction, and current density in the reactor are presented at two inlet temperatures to provide insight into the operation of the reactor. The effects of the inlet temperature, feed flow rate, and cell current on the cell pack voltage and current efficiency of the reactor are presented to determine problematic operating regions for the reactor. Optimum operating currents based …

The Effect Of Particle Size On The Discharge Performance Of A Nickel-Metal Hydride Cell, Jussi M. Heikonen, Harry J. Ploehn, Ralph E. White

Faculty Publications

We investigate the effect of particle size on the discharge performance of a nickel-metal hydride cell with a mathematical model. Electrodes with uniform as well as with nonuniform particle sizes are studied. With uniform particle size, the dependence of the particle-to-particle resistance on the particle size is taken into account. The optimal particle size depends on the discharge rate. Moreover, we show that under certain conditions it is advantageous to use a nonuniform particle size. In general, the higher the discharge current density, the more the particle size affects the electrode performance.

Measurement Of Thin Liquid Film Drainage Using A Novel High-Speed Impedance Analyzer, Kevin O. Hool, Robert C. Saunders, Harry J. Ploehn

Faculty Publications

This work describes the design and implementation of a new instrument, called the thin film impedance analyzer, which measures the rate of drainage of thin oil films. The instrument forms an oil film by elevating a planar oil–water interface into a water drop hanging from a stainless steel capillary tube immersed in the oil. The instrument measures the magnitude of the impedance of the matter between the capillary tube and a screen electrode immersed in the lower water phase. Under appropriate conditions, the capacitance of the oil film dominates the impedance. The instrument records the increase in the magnitude of …

Recovery Of Intracellular Materials By Electroporation, Wendy Elaine Reid

Theses

Electroporation is commonly used to transfer genetic materials such as DNA into the cell by exposing the cell to a high electric field that momentarily permeabilizes the cell membrane. This premise was utilized to use electroporation as a means of releasing intracellular proteins. A procedure has been developed for the release of intracellular proteins through the use of electroporation. This procedure is a breakthrough. In general, industrial scale techniques to recover proteins from microorganisms are inefficient (Clarkson, 1993). A benefit of this electroporation-based mechanism would be the reduction of steps in the downstream processing required to purify the desired product. …

Modeling Soot Derived From Pulverized Coal, Alexander L. Brown, Thomas H. Fletcher

Faculty Publications

A semiempirical model has been developed for predicting coal-derived soot. The main feature of the model is a transport equation for soot mass fraction. Tar prediction options include either an empirical or a transport equation approach, which directly impacts the source term for soot formation. Also, the number of soot particles per unit mass of gas may be calculated using either a transport equation or an assumed average. Kinetics are based on Arrhenius rates taken from published measurements. Radiative properties are calculated as a function of averaged optical constants, predicted gas temperatures, predicted gas densities, and the soot mass fractions. …

Composition Containing A Polymer And Conductive Filler And Use Thereof, Ravi F. Saraf

Department of Chemical and Biomolecular Engineering: Patents

A composition containing a polymeric matrix and a conductive filler component is provided. The conductive filler component comprises conductive particles and a polymer selected from the group consisting of substituted and unsubstituted polyanilines, substituted and unsubstituted polyparaphenylenevinylenes, substituted and unsubstituted polythiophenes, substituted and unsubstituted polyazines, substituted and unsubstituted polyparaphenylenes, substituted and unsubstituted polyfuranes, substituted and unsubstituted polypyrroles, substituted and unsubstituted polyselenophene, substituted and unsubstituted poly-p-phenylene sulfides and substiututed and unsubstituted polyacetylenes, and mixtures thereof, and copolymers thereof. Compositions of the present invention are useful as corrosion protecting layers for metal substrates, for electrostatic discharge protection, electromagnetic interference shielding, and as …

The Activity Of Alloy Cu-Ni Electrode In Electroreduction Of Aromatic Nitro-Compounds, Chunan Ma, Shaoping Tong, Xiaojun Cheng, Hui Wang

Journal of Electrochemistry

Cu-Ni alloy on the basis of copper at different ratio Cu/Ni are prepared by codepostion. The cathode activtiy of film are studied by steady-state polarization for electroreduction nitro-benzene (NB) and 1,5-dinitroanthraquinone (1,5-DNA) to p-aminophenol and 1,5-diamino-4,8-dihydroanthraquinone respectly. The results show that the alloy cathodes at different ratio Cu/Ni have different exchange current density (i^o) and apparent activition energy (E_A). The alloy (CN-30) has maximal i^o and minimal E_A by codeposition at the following conditions: electrolyte: 0.05 mol/L CuSO₄·5H₂O+0.6 mol/L NiSO₄·6H₂O+0.25 mol/L Na₃Cit·2H₂O; …

Study On The Oxygen Electrodes Of Alkaline Fuel Cells Effect Of Dopant On The Activity Of Ag/C Catalyst, Jiawei Teng, Linhua Jin, Luncheng Tang

Journal of Electrochemistry

A new kind of nonnoble catalyst for the oxygen electrodes of Alkaline Fuel Cells was investigated. The AgNiBiHg/C catalyst, which was prepared by chemical reduction, was active for the cathodic reduction of oxygen in alkaline fuel cells. It was found that the catalytic activity was improved by adding Ni, Bi, Hg to Ag/C catalyst, and the maximum activity was observed at Ag50%-Ni2%-Bi3%-Hg3%-C42%(wt%). XRD inconjunction with SEM indicated that the crystalline silver turned into amorphous in the presence of doping agents and the grain size of silver was reduced. No dramatic deactivation of the catalyst occured after 5200 hours of service.

Molten Carbonate Fuel Cell Materials And Technology, Naichao Li, Baolian Yi

Journal of Electrochemistry

Molten Carbonate Fuel Cell materials are reviewed, and the technology of Molten Carbonate Fuel Cell are discussed.

Study On Perchlorate Produced By Electrolysis With Oxygen Cathode, Zhigang Shao, Baolian Yi, Naichao Li, Ming Han

Journal of Electrochemistry

A new method of measuring the flow capacity of cell gas in the perchlorate cell process equipped with an oxygen cathode is applided to investigate the influence of changes in the concentration of solution (chloride, chlorate, perchlorate and metal ion) and changes in the operation parameters (current density, temperature and pH) on perchlorate current efficiency. The main abstacle that the oxygen cathode is used in the perchlorate cell process is put forward and a method is provided to resolve it.

Crossflow Microfiltration Of Recombinant Escherichia Coli Lysates After High Pressure Homogenization, Stuart M. Bailey, Michael M. Meagher

Papers in Biotechnology

Abstract: Crossflow membrane filtration was used to process recombinant Escherichia coli cell lysates containing protein inclusion bodies after high pressure homogenization. The number of passes through the high pressure homogenizer changed the viscosities and average particle sizes of the cell lysates. The different cell lysates were processed with a hollow fiber unit containing microfiltration membranes and a plate and frame unit with either ultrafiltration or microfiltration membranes. There were differences in permeate flux and protein transmission for the various membranes with the best performing membranes giving permeate fluxes greater than 60 L m−2 h−1 and protein transmissions greater than 90%. …

Phase Diagrams Of A Binary Smectic-A Mixture, Hao-Wen Chiu, Thein Kyu

College of Polymer Science and Polymer Engineering

A variety of smectic phase diagrams involving smectic-isotropic and smectic-nematic-isotropic transitions have been calculated based on a combination of Flory-Huggins (FH) theory for isotropic mixing and Maier-Saupe-McMillan (MSM) theory for smectic-A ordering of liquid crystals (LC). To describe the mesophase transitions, two nematic order parameters and two smectic order parameters have been coupled through the normalized orientation distribution and partition functions. Flory-Huggins interaction parameter (chi) for isotropic mixing and the coupling term involving the nematic interaction parameter (nu) and the McMillan smectic interaction parameter (alpha) for phase transitions of liquid crystals have been incorporated in the calculation. The predictive capability …

Mixed Metal Removal And Recovery By Hollow Fiber Membrane-Based Extractive Adsorber, Ramprakash Chilukuri

Theses

The feasibility and efficiency of simultaneous removal of multiple cations as well as anionic heavy metals from wastewater into a mixed extractant kept stagnant on the shell side of a 2-fiber-set hollow fiber membrane extractor operated as a fixed bed adsorber was explored. The novel extracting solvent was a mixture of an acidic or chelating extracting agent for one or more cations and a basic extracting agent, e.g., trioctylamine (TOA) for extracting anions; both were dissolved in the same diluent kerosene for simultaneous and synergistic extraction of cations and anions. In the stripping part of the fixed bed operation, alkaline …

Pervaporation-Assisted Esterification Of Salicylic Acid, Chaiya Chandavasu

Theses

The coupling of a pervaporation membrane unit with a reactor has been investigated as a means of improving the overall process efficiency. As model system, the esterification of salicylic acid with methanol in the presence of a homogeneous catalyst was studied in a unit consisting of a batch reactor externally coupled with a pervaporation module containing a composite poly(vinyl alcohol) membrane. The reaction was carried out at temperatures between 336 and 345 K. The catalyst was sulfuric acid at concentrations varying from 0.5 to 2.0 molar. Various initial molar ratios (Θ_B) of methanol and salicylic acid, ranging from …

Biodegradation Of Naphthalene Using Pseudomonas Putida (Atcc 17484) In Batch And Chemostat Reactors, Jay Boyd Best

Theses

Kinetic experiments were conducted using Pseudomonas putida (ATCC 17484) to determine the rate of growth when naphthalene was provided as a sole carbon source in suspended biomass systems. Batch and chemostat reactors were used under three sets of conditions: non-aerated, aerated at 29.5° C, and aerated at 25.5° C. A number of concentrations were tested under each set of conditions. Data regression was used to determine parameters for Monod (non-inhibitory), Andrews (inhibitory), and zero-order kinetics. Although the Andrews fit of the data provided a slightly lower sum-of-squares error (SSE), the amount of data scatter and the weak inhibition made the …

Soot Capture In An Electrocatalytic Reactor, Thana Slanvetpan

Theses

A major problem with many soot emission control devices is the fact that they quickly become loaded with soot which must be removed by a regeneration process. A soot capture reactor using a large flow channel was studied in order to eliminate channel plugging and avoid regeneration. Electrostatic precipitation was used in order to enhance particle diffusion to the catalyst wall of the reactor tube. The system effectiveness for soot capture was measured with filter paper sampling of the incoming versus the outgoing flow through the reactor. Soot filter loadings were analyzed by laser optical transmission. From the soot filter …

Development Of Aqueous Scrubber To Oxidize And Absorb Nitric Oxide, Wanna Lolertpiphop

Theses

The use of sodium chlorite (NaClO₂) and alkaline aqueous cumene hydroperoxide (CHP) as oxidizing agents to promote the absorption of nitric oxide from flue gases was investigated in a semicontinuous bubbling scrubber. The efficiency of the scrubbing solutions to remove nitric oxide was evaluated as a function of operating conditions such as pH, concentration of the oxidants, residence time, temperature, flue gas compositions.

Under acid conditions, sodium chlorite can stoichiometrically react and absorb 99.5% NO and 80% SO₂ in the same scrubber with 0,672 M NaClO₂ in buffered solution at pH 6, and 0.3 M NaOH. …