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Articles 1 - 14 of 14
Full-Text Articles in Chemical Engineering
Interfacial Stability Of Electrodeposition Of Cuprous Oxide Thin Films, Partho Neogi
Interfacial Stability Of Electrodeposition Of Cuprous Oxide Thin Films, Partho Neogi
Chemical and Biochemical Engineering Faculty Research & Creative Works
Experiments on deposition of Cu2O films from basic cupper sulfate solution show that copper also deposits. At low, but basic values of pH only copper deposits and at high pH only cuprous oxide deposits. In the intermediate range where both compete the system shows oscillations at "constant current." Linear stability analysis has been conducted for such an electrochemical cell to show that oscillations can take place in the parameter space identified in the experiments. The results are keeping with most of the experimental observations, which are many, but not with all. The physical mechanisms behind the oscillations are …
Optimization Of Batch Reactions In Series With Uncertainty, Keith G. Tomazi
Optimization Of Batch Reactions In Series With Uncertainty, Keith G. Tomazi
Chemical and Biochemical Engineering Faculty Research & Creative Works
Certain types of chemical reactions, such as the global deprotection of a polypeptide, are extremely complex. As a result, it may be very difficult or expensive to develop accurate models of these chemical reactions. Without a satisfactory kinetic model for the reaction, it is difficult to develop an optimum operating policy that will maximize the profit. Stochastic optimization is applied in this work to an example process step to obtain the optimum reaction temperature and reaction time. In the case of the "here and now" problem, the optimal conditions are a lower reaction temperature and a longer reaction time than …
Liquid Holdup And Pressure Drop In The Gas-Liquid Cocurrent Downflow Packed-Bed Reactor Under Elevated Pressures, Jing Guo, Muthanna H. Al-Dahhan
Liquid Holdup And Pressure Drop In The Gas-Liquid Cocurrent Downflow Packed-Bed Reactor Under Elevated Pressures, Jing Guo, Muthanna H. Al-Dahhan
Chemical and Biochemical Engineering Faculty Research & Creative Works
An Experimental Investigation of the Residence Time Distribution, Liquid Holdup, and Pressure Drop in a Gas-Liquid Downflow Packed Bed Reactor with Porous Particles Operated under Elevated Pressures is Presented. the Effects of the Two-Phase Flow Rates and Reactor Pressures on the External Liquid Holdup and Pressure Drop Are Discussed. a Mechanistic Model, Which Accounts for the Interaction between the Gas and Liquid Phases by Incorporating the Shear and Velocity Slip Factors between Phases, is Employed to Predict the External Liquid Holdup and Pressure Drop for the Experimentally Covered Flow Regime. the Involved Parameters, Such as Shear and Velocity Slip Factors …
Monoliths As Multiphase Reactors: A Review, Shaibal Roy, Tobias Bauer, Muthanna H. Al-Dahhan, Peter Lehner, Thomas Turek
Monoliths As Multiphase Reactors: A Review, Shaibal Roy, Tobias Bauer, Muthanna H. Al-Dahhan, Peter Lehner, Thomas Turek
Chemical and Biochemical Engineering Faculty Research & Creative Works
Monolith Reactors Are Being Studied as a Replacement for Conventional Multiphase Reactors Such as Trickle-Bed Reactors, Slurry Reactors, and Slurry Bubble Column Reactors for Gas-Liquid-Solid Reactions. Reactors with Monolith Catalyst Packing Have Been Found to Be Hydrodynamically Superior to Existing Industrial Reactors. This Review Covers Multiphase Reactions Carried Out in Monolith Reactors by Various Researchers. It First Defines the Monolith Reactor and Looks into the Geometrical Aspects of Monolith. the Section Dealing with Hydrodynamics Reviews Pressure Drop, Phase Holdup, Flow Distribution, and Dispersion Characteristics. This Study Also Considers the Tools Used to Characterize the Hydrodynamic Parameters and their Typical Values. …
Quantification Of Solids Flow In A Gas-Solid Riser: Single Radioactive Particle Tracking, Satish Bhusarapu, Muthanna H. Al-Dahhan, Milorad P. Dudukovic
Quantification Of Solids Flow In A Gas-Solid Riser: Single Radioactive Particle Tracking, Satish Bhusarapu, Muthanna H. Al-Dahhan, Milorad P. Dudukovic
Chemical and Biochemical Engineering Faculty Research & Creative Works
Solids in Risers of Circulating Fluidized Beds (CFB) Exhibit Local Backflow and Recirculation. Measurement of the Concentration-Time Response to an Impulse Injection of Tracer, Even at Two Elevations Cannot Determine the Residence Time Distribution (RTD) of Solids Uniquely. Hence, Evaluation of RTD in Risers from Conventional Tracer Responses is Difficult and Often Not Possible. in Addition, Estimating the Solids Circulation Rate in These Closed Loop Systems, is a Non-Trivial Problem. in This Work, a Single Radioactive Particle in the CFB Loop is Tracked during its Multiple Visits to the Riser And, by Invoking Ergodicity, Solids Circulation Rate, Accurate Solids RTD …
Determining Suitability Of A Fly Ash For Silica Extraction And Zeolite Synthesis, Natàlia Moreno, Xavier Querol, Angel López-Soler, José Manuel Andres, Maria Janssen, Henk Nugteren, Mark R. Towler, Kenneth Stanton
Determining Suitability Of A Fly Ash For Silica Extraction And Zeolite Synthesis, Natàlia Moreno, Xavier Querol, Angel López-Soler, José Manuel Andres, Maria Janssen, Henk Nugteren, Mark R. Towler, Kenneth Stanton
Chemical and Biochemical Engineering Faculty Research & Creative Works
Zeolitic material is obtained from fly ash both by direct conversion of the ash or from SiO2 extracts obtained from fly ash. This study focuses on determining the suitability of a fly ash for SiO2 extraction and for zeolite synthesis by direct conversion. The SiO2 extraction experiments from different fly ashes show that the main parameters governing the SiO2 extraction are: (a) a high bulk SiO2 content (> 52%, for obtaining an extraction yield of 100 g SiO2 kg-1) in the starting fly ash, (b) a high proportion (> 55%) of the bulk SiO …
Induced Defects In Carbonaceous Materials For Hydrogen Storage, Angela D. Lueking, Caroline E. Burgess Clifford, Deepa L. Narayanan
Induced Defects In Carbonaceous Materials For Hydrogen Storage, Angela D. Lueking, Caroline E. Burgess Clifford, Deepa L. Narayanan
Chemical and Biochemical Engineering Faculty Research & Creative Works
The induced defects in carbonaceous materials for hydrogen storage were studied. The effect of exfoliation was studied and the graphite nanofibers (GNF) diameter before and after exfoliation was quantified. Thermal decomposition of the GNF before and after sulfuric/nitric acid exfoliation indicated a clear loss of thermal stability. GNF exfoliation enhanced the hydrogen uptake by a factor of five compared to the untreated GNF. The amorphous carbon was reactive than GNF, and decomposed before the GNF. The higher pretreatment temperature was intended to preferentially remove amorphous carbon leaving a higher purity of exfoliated GNF.
Investigation Into The Ultrasonic Setting Of Glass Ionomer Cements : Part Ii Setting Times And Compressive Strengths, E. Twomey, Mark R. Towler, C. M. Crowley, J. Doyle, S. Hampshire
Investigation Into The Ultrasonic Setting Of Glass Ionomer Cements : Part Ii Setting Times And Compressive Strengths, E. Twomey, Mark R. Towler, C. M. Crowley, J. Doyle, S. Hampshire
Chemical and Biochemical Engineering Faculty Research & Creative Works
The ultrasonic setting of glass ionomer cements (GIC) was discussed. It was observed that the ultrasonic setting resulted in improvements of compressive strength. An increase in the PAA molecular weight from PAA50 to PAA200 resulted in an increase in the strength, but with a further increase in the PAA molecular weight to PAA450, there was a reduction in the strength. Results show that the strength of the ultrasonically set materials after 1 day were close to the values for the 7 days chemically set samples.
The Influence Of Strontium Substitution In Fluorapatite Glasses And Glass-Ceramics, R. G. Hill, A. Stamboulis, R. V. Law, A. Clifford, Mark R. Towler, C. Crowley
The Influence Of Strontium Substitution In Fluorapatite Glasses And Glass-Ceramics, R. G. Hill, A. Stamboulis, R. V. Law, A. Clifford, Mark R. Towler, C. Crowley
Chemical and Biochemical Engineering Faculty Research & Creative Works
Strontium is often substituted for calcium in order to confer radio-opacity in glasses used for dental cements, Biocomposites and bio glass-ceramics. The present paper investigates the influence of substituting strontium for calcium in a glass of the following composition: 4.5SiO23Al2O 31.5P2O53CaO2CaF2, having a Ca:P ratio of 1.67 corresponding to calcium fluorapatite (Ca5(PO 4)3F). The glasses were characterized by magic angle spinning nuclear magnetic resonance (MAS-NMR), by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRD). The 29Si, 27Al and 31P NMR spectra for the glasses with …
Characterisation Of The Glass Fraction Of A Selection Of European Coal Fly Ashes, J. Henry, Mark R. Towler, K. T. Stanton, X. Querol, N. Moreno
Characterisation Of The Glass Fraction Of A Selection Of European Coal Fly Ashes, J. Henry, Mark R. Towler, K. T. Stanton, X. Querol, N. Moreno
Chemical and Biochemical Engineering Faculty Research & Creative Works
Fly ash largely consists of the inorganic content of coal that remains after combustion. The crystalline phases present in fly ash may form upon cooling of a molten alumino-silicate glass. This view is supported by the spherical shape of many fly ash particles, inferring that they have gone through a viscous fluid state. The amorphous content in fly ash is believed to dominate reactivity behaviour, under both alkaline and acid conditions, because glasses have a higher potential energy than the equivalent crystal structure and the variation of bond angles and distances in a glass makes the bond breakage easier. It …
A Sequential Approach To Modeling Catalytic Reactions In Packed-Bed Reactors, Jing Guo, Muthanna H. Al-Dahhan
A Sequential Approach To Modeling Catalytic Reactions In Packed-Bed Reactors, Jing Guo, Muthanna H. Al-Dahhan
Chemical and Biochemical Engineering Faculty Research & Creative Works
A Sequential Modeling Approach is Proposed to Simulate Catalytic Reactions in Packed-Bed Reactors. the Hydrogenation of Alpha-Methylstyrene and Wet Oxidation of Phenol Are Selected as Studied Cases. the Modeling Scheme Combines a Reactor Scale Axial Dispersion Model with a Pellet Scale Model. Without Involving Any Fitting Parameters, Such an Approach Accounts for the Non-Linear Reaction Kinetics Expression and Different Types of Pellet-Liquid Wetting Contact. to Validate the Developed Modeling Scheme and the Parallel Approach Reported in the Literature, the Experimental Observations for Hydrogenation of Alpha-Methylstyrene to Cumene Have Been Employed. the Predicted Results by Both Approaches Agree Reasonably with the …
Dynamic Contact Angles Under Evaporation, Robert M. Ybarra, Partho Neogi
Dynamic Contact Angles Under Evaporation, Robert M. Ybarra, Partho Neogi
Chemical and Biochemical Engineering Faculty Research & Creative Works
Wetting kinetics in the presence of heat transfer, evaporation, and Marangoni effect has been explored using a method used by Joanny and de Gennes [C. R. Acad. Sci. Ser. II 299, 279 (1984)]. The method solves for the dynamic contact angle alpha by equating the rate of surface work to the rate of dissipation. The result in the form of dynamic contact angle alpha as a function of capillary number Ca agrees well with existing experimental data. Qualitative comparisons have been made in cases where quantitative data do not exist. Finally, a form of contact line instability is predicted, for …
Analyzing And Modeling Of Photobioreactors By Combining First Principles Of Physiology And Hydrodynamics, Hu Ping Luo, Muthanna H. Al-Dahhan
Analyzing And Modeling Of Photobioreactors By Combining First Principles Of Physiology And Hydrodynamics, Hu Ping Luo, Muthanna H. Al-Dahhan
Chemical and Biochemical Engineering Faculty Research & Creative Works
Mixing in Photobioreactors is Known to Enhance Biomass Productivity Considerably, and Flow Dynamics Play a Significant Role in the Reactor's Performance, as They Determine the Mixing and the Cells' Movement. in This Work We Focus on Analyzing the Effects of Mixing and Flow Dynamics on the Photobioreactor Performance. based on Hydrodynamic Findings from the CARPT(Computer Automated Radioactive Particle Tracking) Technique, a Possible Mechanism for the Interaction between the Mixing and the Physiology of Photosynthesis is Presented, and the Effects of Flow Dynamics on Light Availability and Light Intensity Fluctuation Are Discussed and Quantitatively Characterized. Furthermore, a Dynamic Modeling Approach is …
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 …