Open Access. Powered by Scholars. Published by Universities.®

Chemical Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Faculty Publications

Discipline
Institution
Keyword
Publication Year
File Type

Articles 301 - 330 of 914

Full-Text Articles in Chemical Engineering

Examination Of The Effect Of Differential Molecular Diffusion In Dns Of Turbulent Non-Premixed Flames, Chao Han, David O. Lignell, Evatt R. Hawkes, Jacqueline H. Chen, Haifeng Wang Feb 2017

Examination Of The Effect Of Differential Molecular Diffusion In Dns Of Turbulent Non-Premixed Flames, Chao Han, David O. Lignell, Evatt R. Hawkes, Jacqueline H. Chen, Haifeng Wang

Faculty Publications

The effect of differential molecular diffusion (DMD) in turbulent non-premixed flames is studied by examining two previously reported DNS of temporally evolving planar jet flames, one with CO/H2 as the fuel and the other with C2H4 as the fuel. The effect of DMD in the CO/H2 DNS flames in which H2 is part of fuel is found to behave similar to laminar flamelet, while in the C2H4 DNS flames in which H2 is not present in the fuel it is similar to laminar flamelet in early stages but becomes different from laminar flamelet later. The scaling of the effect …

Go to article

Electroanalytical Measurements Of Binary-Analyte Mixtures In Molten Licl-Kcl Eutectic: Uranium(Iii)- And Magnesium(Ii)-Chloride, Devin Rappleye, Matthew L. Newton, Chao Zhang, Michael F. Simpson Feb 2017

Electroanalytical Measurements Of Binary-Analyte Mixtures In Molten Licl-Kcl Eutectic: Uranium(Iii)- And Magnesium(Ii)-Chloride, Devin Rappleye, Matthew L. Newton, Chao Zhang, Michael F. Simpson

Faculty Publications

The electrochemical behavior of MgCl2 in molten LiCl-KCl eutectic was investigated to evaluate its suitability as a surrogate for PuCl3 in studies related to the eletrorefining of used nuclear fuel. The reduction of Mg2+ was found to be electrochemically reversible up to 300 mV s−1 at 773 K. The diffusion coefficient for Mg2+ was calculated to be 1.74 and 2.17 × 10−5 cm2 s−1 with and without U3+ present, respectively, at 773 K using cyclic voltammetry (CV). Upon comparison to literature data, the diffusion coefficient of Mg2+ differs by only 8.8% (with U …

Go to article

Hybrid Concentrated Solar Thermal Power Systems: A Review, Kody M. Powell, Khalid Rashid, Kevin Ellingwood, Jake Tuttle, Brian D. Iverson Jan 2017

Hybrid Concentrated Solar Thermal Power Systems: A Review, Kody M. Powell, Khalid Rashid, Kevin Ellingwood, Jake Tuttle, Brian D. Iverson

Faculty Publications

Concentrated solar power (CSP), or solar thermal power, is an ideal technology to hybridize with other energy technologies for power generation. CSP shares technology with conventional power generation and can be readily integrated with other energy types into a synergistic system, which has many potential benefits including increased dispatchability and reliability, improved efficiency, reduced capital costs through equipment sharing, and the opportunity for flexible operation by alternating between energy sources. Another advantage of CSP technology is the ability to readily store via thermal energy storage (TES), making the intermittent solar resource dispatchable. A review of CSP hybridization strategies with coal, …

Go to article

Study Potential Of Indigenous Pseudomonas Aeruginosa And Bacillus Subtilis In Bioremediation Of Diesel-Contaminated Water, Mohammad-Saeed Safdari, Hamid-Reza Kariminia, Zahra Ghobadi Nejad, Thomas H. Fletcher Jan 2017

Study Potential Of Indigenous Pseudomonas Aeruginosa And Bacillus Subtilis In Bioremediation Of Diesel-Contaminated Water, Mohammad-Saeed Safdari, Hamid-Reza Kariminia, Zahra Ghobadi Nejad, Thomas H. Fletcher

Faculty Publications

Petroleum products which are used in a wide variety of industries as energy sources and raw materials have become a major concern in pollution of terrestrial and marine environments. The purpose of this study was to assess the potential of indigenous microbial isolates for degradation of diesel fuel. Two most proficient bacterial strains among five isolated strains from polluted soil of an industrial refinery were studied. The isolates then were identified as Pseudomonas aeruginosa and Bacillus subtilis using biochemical tests and 16S rRNA gene sequence analyses. P. aeruginosa showed higher biodegradation efficiency than B. subtilis in shaking flask containing diesel-contaminated …

Go to article

Optimal Combined Long-Term Facility Design And Short-Term Operational Strategy For Chp Capacity Investments, Jose Mojica, Damon Petersen, Brigham Hansen, Kody Powell, John Hedengren Jan 2017

Optimal Combined Long-Term Facility Design And Short-Term Operational Strategy For Chp Capacity Investments, Jose Mojica, Damon Petersen, Brigham Hansen, Kody Powell, John Hedengren

Faculty Publications

This work presents a detailed case study for the optimization of the expansion of a district energy system evaluating the investment decision timing, type of capacity expansion, and fine-scale operational modes. The study develops an optimization framework to find the investment schedule over 30 years with options of investing in traditional heating sources (boilers) or a next-generation combined heat and power (CHP) plant that provides heat and electricity. In district energy systems, the selected capacity and type of system is dependent on demand-side requirements, energy prices, and environmental costs. This work formulates capacity planning over a time horizon as a …

Go to article

Modeling Effects Of Annealing On Coal Char Reactivity To O2 And Co2, Based On Preparation Conditions, Troy Michael Holland, Sham Bhat, Peter Marcy, James Gattiker, Joel D. Kress, Thomas H. Fletcher Jan 2017

Modeling Effects Of Annealing On Coal Char Reactivity To O2 And Co2, Based On Preparation Conditions, Troy Michael Holland, Sham Bhat, Peter Marcy, James Gattiker, Joel D. Kress, Thomas H. Fletcher

Faculty Publications

Oxy-fired coal combustion is a promising potential carbon capture technology. Predictive computational fluid dynamics (CFD) simulations are valuable tools in evaluating and deploying oxyfuel and other carbon capture technologies, either as retrofit technologies or for new construction. However, accurate predictive combustor simulations require physically realistic submodels with low computational requirements. A recent sensitivity analysis of a detailed char conversion model (Char Conversion Kinetics (CCK)) found thermal annealing to be an extremely sensitive submodel. In the present work, further analysis of the previous annealing model revealed significant disagreement with numerous datasets from experiments performed after that annealing model was developed. The …

Go to article

Comprehensive Model Of Single Particle Pulverized Coal Combustion Extended To Oxy-Coal Conditions, Troy Michael Holland, Thomas H. Fletcher Jan 2017

Comprehensive Model Of Single Particle Pulverized Coal Combustion Extended To Oxy-Coal Conditions, Troy Michael Holland, Thomas H. Fletcher

Faculty Publications

Oxy-fired coal combustion is a promising potential carbon capture technology. Predictive CFD simulations are valuable tools in evaluating and deploying oxy-fuel and other carbon capture technologies either as retrofit technologies or for new construction. However, accurate predictive simulations require physically realistic submodels with low computational requirements. In particular, comprehensive char oxidation and gasification models have been developed that describe multiple reaction and diffusion processes. This work extends a comprehensive char conversion code (CCK), which treats surface oxidation and gasification reactions as well as processes such as film diffusion, pore diffusion, ash encapsulation, and annealing. In this work several submodels in …

Go to article

Semi-Empirical Model For Fire Spread In Shrubs With Spatially-Defined Fuel Elements And Flames, Dallan Prince, Chen Shen, Thomas H. Fletcher Jan 2017

Semi-Empirical Model For Fire Spread In Shrubs With Spatially-Defined Fuel Elements And Flames, Dallan Prince, Chen Shen, Thomas H. Fletcher

Faculty Publications

A semi-empirical model was developed which forms shrub geometries from distinct fuel elements (e.g. leaves) and describes flame spread from element to element. Ignition, flame growth and flame decay patterns were based on combustion data of single leaves. Extension of the model to various heating conditions was achieved by scaling the flame growth parameters using physics-based heat transfer models. The resulting model offers a novel approach to examine fire spread and to explicitly describe both distinct fuel elements and fire behavior. This approach balances computational speed and modeling detail while providing a unique perspective into fire spread phenomena. Comparisons of …

Go to article

Modeling Soot Oxidation And Gasification With Bayesian Statistics, Alexander Jon Josephson, Neal D. Gaffin, Sean T. Smith, Thomas H. Fletcher, David Lignell Jan 2017

Modeling Soot Oxidation And Gasification With Bayesian Statistics, Alexander Jon Josephson, Neal D. Gaffin, Sean T. Smith, Thomas H. Fletcher, David Lignell

Faculty Publications

This paper presents a statistical method for model calibration using data collected from literature. The method is used to calibrate parameters for global models of soot consumption in combustion systems. This consumption is broken into two different submodels: first for oxidation where soot particles are attacked by certain oxidizing agents; second for gasification where soot particles are attacked by H2O or CO2 molecules. Rate data were collected from 19 studies in the literature and evaluated using Bayesian statistics to calibrate the model parameters. Bayesian statistics are valued in their ability to quantify uncertainty in modeling. The calibrated consumption model with …

Go to article

Model For The Evolution Of Pore Structure In A Lignite Particle During Pyrolysis. 2. Influence Of Cross-Linking Reactions, Molten Metaplast, And Molten Ash On Particle Surface Area, He Yang, Thomas H. Fletcher, Sufen Li, Haoquan Hu, Lijun Li Jan 2017

Model For The Evolution Of Pore Structure In A Lignite Particle During Pyrolysis. 2. Influence Of Cross-Linking Reactions, Molten Metaplast, And Molten Ash On Particle Surface Area, He Yang, Thomas H. Fletcher, Sufen Li, Haoquan Hu, Lijun Li

Faculty Publications

A model for the evolution of the pore structure in a lignite particle during pyrolysis was established previously based on the chemical percolation devolatilization (CPD) model, using coal polymer network parameters to calculate the surface area and porosity of the particle. In this paper, to get the accurate surface area of coal particle at high pyrolysis temperature, the previous model was improved by considering the effects of cross-linking reactions, molten Metaplast, and ash. The good agreement of the predicted surface area with experiments at temperature below 1200 K in the previous model is maintained, and model accuracy is improved at …

Go to article

Evolutionary View Planning For Optimized Uav Terrain Modeling In A Simulated Environment, Ronald A. Martin, Ivan Rojas, Kevin W. Franke, John Hedengren Dec 2016

Evolutionary View Planning For Optimized Uav Terrain Modeling In A Simulated Environment, Ronald A. Martin, Ivan Rojas, Kevin W. Franke, John Hedengren

Faculty Publications

This work demonstrates the use of genetic algorithms in optimized view planning for 3D reconstruction applications using small unmanned aerial vehicles (UAVs). The quality of UAV site models is currently highly dependent on manual pilot operations or grid-based automation solutions. When applied to 3D structures, these approaches can result in gaps in the total coverage or inconsistency in final model resolution. Genetic algorithms can effectively explore the search space to locate image positions that produce high quality models in terms of coverage and accuracy. A fitness function is defined, and optimization parameters are selected through semi-exhaustive search. A novel simulation …

Go to article

Soot Oxidation By Oh: Theory Development, Model, And Experimental Validation, Hossein Ghiassi, David Lignell, Joann S. Lighty Dec 2016

Soot Oxidation By Oh: Theory Development, Model, And Experimental Validation, Hossein Ghiassi, David Lignell, Joann S. Lighty

Faculty Publications

Soot oxidation by OH has been represented by an equation developed by Neoh that includes the efficiency of OH radicals to react, the collision efficiency. The focus of this study is the theoretical development of the collision efficiency, enabling a more accurate prediction of soot oxidation where OH is the principle oxidizer. In addition to the traditional parameters, such as OH concentration and temperature, this approach aims to improve the prediction of soot oxidation by considering the fraction of the active area as well as the size of the soot particle and aggregate. The fraction of the active area was …

Go to article

A Comparison Of Lysophosphatidylcholine And Crush Injury In A Rat Model Of Sciatic Nerve Regeneration, Ryan L. Wood, William G. Pitt, Scott C. Steffensen, Alonzo D. Cook Dec 2016

A Comparison Of Lysophosphatidylcholine And Crush Injury In A Rat Model Of Sciatic Nerve Regeneration, Ryan L. Wood, William G. Pitt, Scott C. Steffensen, Alonzo D. Cook

Faculty Publications

This study examined the effect of using lysophosphatidyl choline (LPC) in combination with a nerve crush injury on the healing rate of damaged left sciatic nerves in female rats. The rats were divided randomly into four groups: Control, LPC, Crush or Crush+ LPC. The Control group was the undamaged right sciatic nerve. The other groups were the damaged left sciatic nerve. The healing of the nerves was measured by monitoring gait, electrophysiological parameters: compound muscle action potential (CMAP) amplitudes and nerve conductance velocities (NCV); and morphological parameters: total fascicular area, total myelinated fiber counts, fiber densities, fiber diameters, and g-ratio. …

Go to article

Fabrication Of High Performing Pemfc Catalyst-Coated Membranes With A Low Cost Air-Assisted Cylindrical Liquid Jets Spraying System, Xiong Peng, Travis Omasta, William Rigdon, William E. Mustain Nov 2016

Fabrication Of High Performing Pemfc Catalyst-Coated Membranes With A Low Cost Air-Assisted Cylindrical Liquid Jets Spraying System, Xiong Peng, Travis Omasta, William Rigdon, William E. Mustain

Faculty Publications

In this work, a low cost air-assisted cylindrical liquid jets spraying (ACLJS) system was developed to prepare high-performance catalyst-coated membranes (CCMs) for proton exchange membrane fuel cells (PEMFCs). The catalyst ink was flowed from a cylindrical orifice and was atomized by an air stream fed from a coaxial slit and sprayed directly onto the membrane, which was suctioned to a heated aluminum vacuum plate. The CCM pore architecture including size, distribution and volume can be controlled using various flow parameters, and the impact of spraying conditions on electrode structure and PEMFC performance was investigated. CCMs fabricated in the fiber-type break-up …

Go to article

Evaluation Of Stochastic Particle Dispersion Modeling In Turbulent Round Jets, Guangyuan Sun, John C. Hewson, David O. Lignell Nov 2016

Evaluation Of Stochastic Particle Dispersion Modeling In Turbulent Round Jets, Guangyuan Sun, John C. Hewson, David O. Lignell

Faculty Publications

ODT (one-dimensional turbulence) simulations of particle-carrier gas interactions are performed in the jet flow configuration. Particles with different diameters are injected onto the centerline of a turbulent air jet. The particles are passive and do not impact the fluid phase. Their radial dispersion and axial velocities are obtained as functions of axial position. The time and length scales of the jet are varied through control of the jet exit velocity and nozzle diameter. Dispersion data at long times of flight for the nozzle diameter (7 mm), particle diameters (60 and 90 µm), and Reynolds numbers (10, 000–30, 000) are …

Go to article

Investigation Of The Effects Of Uranium(Iii)-Chloride Concentration On Voltammetry In Molten Licl-Kcl Eutectic With A Glass Sealed Tungsten Electrode, Devin Rappleye, Kevin Teaford, Michael F. Simpson Oct 2016

Investigation Of The Effects Of Uranium(Iii)-Chloride Concentration On Voltammetry In Molten Licl-Kcl Eutectic With A Glass Sealed Tungsten Electrode, Devin Rappleye, Kevin Teaford, Michael F. Simpson

Faculty Publications

One of the major sources of error for electroanalytical measurements in high-temperature molten salts is from the measurement of the working electrode (WE) area. A glass sealed working electrode (GSWE) was developed in order to set the exposed area of tungsten and reduce the error associated with WE area. The insulating property of the glass while in contact with molten salt was verified by observing the independence of electrochemical signals with adjustments in the WE position. The integrity of the glass coating was also confirmed by observing the stability of electrochemical signals (±1.9%) over several hours. Cyclic voltammetry (CV) and …

Go to article

Development And Optimization Of Voltammetry For Real Time Analysis Of Multi-Component Electrorefiner Salt, Chao Zhang, Devin Rappleye, Michael F. Simpson Oct 2016

Development And Optimization Of Voltammetry For Real Time Analysis Of Multi-Component Electrorefiner Salt, Chao Zhang, Devin Rappleye, Michael F. Simpson

Faculty Publications

Normal pulse voltammetry was performed on LiCl-KCl-UCl3- MgCl2 molten salt mixtures while varying parameters such as pulse time, relaxation potential, and interval time. Concentrations of UCl3 up to 7 wt% were tested with a fixed 1.5 wt% MgCl2 concentration. The correlation between diffusion limited partial current density to UCl3 concentration exhibited an excellent fit to a 2nd order polynomial. A similar fit was obtained for the correlation between MgCl2 concentration and the diffusion limited partial current density at a fixed UCl3 concentration of 1.0 wt%.

Go to article

Goggatomy: A Method For Opening Small Cuticular Compartments In Arthropods For Physiological Experiments, Alan R. Kay, Davide Raccuglia, Jon Scholte, Elene Sivan-Loukianova, Chirstopher A. Barwacz, Steven R. Armstrong, C. Allan Guymon, Michael N. Nitabach, Daniel F. Eberl Sep 2016

Goggatomy: A Method For Opening Small Cuticular Compartments In Arthropods For Physiological Experiments, Alan R. Kay, Davide Raccuglia, Jon Scholte, Elene Sivan-Loukianova, Chirstopher A. Barwacz, Steven R. Armstrong, C. Allan Guymon, Michael N. Nitabach, Daniel F. Eberl

Faculty Publications

Most sense organs of arthropods are ensconced in small exoskeletal compartments that hinder direct access to plasma membranes. We have developed a method for exposing live sensory and supporting cells in such structures. The technique uses a viscous light cured resin to embed and support the structure, which is then sliced with a sharp blade. We term the procedure a “goggatomy,” from the Khoisan word for a bug, gogga. To demonstrate the utility of the method we show that it can be used to expose the auditory chordotonal organs in the second antennal segment and the olfactory receptor neurons …

Go to article

Application Of Voltammetry For Electroanalytical Measurement Of Concentrations In Lacl3-Mgcl2 Mixtures In Eutectic Licl-Kcl, Zhonghang Wang, Devin Rappleye, C S. Yang, Michael Simpson Aug 2016

Application Of Voltammetry For Electroanalytical Measurement Of Concentrations In Lacl3-Mgcl2 Mixtures In Eutectic Licl-Kcl, Zhonghang Wang, Devin Rappleye, C S. Yang, Michael Simpson

Faculty Publications

For electroanalytical measurement of molten chloride salts, various voltammetry methods have been used on mixtures of MgCl2 and LaCl3 in eutectic LiCl-KCl. These salt mixtures are of primary interest to spent nuclear fuel electrorefining systems. MgCl2 is used as a surrogate for PuCl3, while LaCl3 represents rare earth fission product salts. Cyclic voltammetry scans with these salt mixtures exhibited extra peaks, presumably due to underpotential deposition of La(III) ions onto Mg. Quantitatively, the current contribution from each peak was best determined using normal pulse voltammetry and fit to the Cottrell equation. This yielded linear …

Go to article

Comparison Of Sfm Computer Vision Point Clouds Of A Landslide Derived From Multiple Small Uav Platforms And Sensors To A Tls Based Model, Samantha Ruggles, Joseph Clark, Kevin W. Franke, Derek Wolfe, Brandon Reimschiissel, Ronald Abraham Martin, Trent Okeson, John Hedengren Jul 2016

Comparison Of Sfm Computer Vision Point Clouds Of A Landslide Derived From Multiple Small Uav Platforms And Sensors To A Tls Based Model, Samantha Ruggles, Joseph Clark, Kevin W. Franke, Derek Wolfe, Brandon Reimschiissel, Ronald Abraham Martin, Trent Okeson, John Hedengren

Faculty Publications

Structure from motion (SfM) computer vision is a remote sensing method that is gaining popularity due to its simplicity and ability to accurately characterize site geometry in three dimensions (3D). While many researchers have demonstrated the potential for SfM to be used with unmanned aerial vehicles (UAVs) to model in three dimensions various geologic features such as landslides, little is understood how the selection of the UAV platform can affect the resolution and accuracy of the model. This study evaluates the resolution and accuracy of 3D point cloud models of a large landslide that occurred in 2013 near Page, Arizona …

Go to article

Highly Conductive In-Sno2/Rgo Nano-Heterostructures With Improved Lithium-Ion Battery Performance, Ying Liu, Alessandro Palmieri, Junkai He, Yongtao Meng, Nicole Beauregard, Steven L. Suib, William E. Mustain May 2016

Highly Conductive In-Sno2/Rgo Nano-Heterostructures With Improved Lithium-Ion Battery Performance, Ying Liu, Alessandro Palmieri, Junkai He, Yongtao Meng, Nicole Beauregard, Steven L. Suib, William E. Mustain

Faculty Publications

The increasing demand of emerging technologies for high energy density electrochemical storage has led many researchers to look for alternative anode materials to graphite. The most promising conversion and alloying materials do not yet possess acceptable cycle life or rate capability. In this work, we use tin oxide, SnO2, as a representative anode material to explore the influence of graphene incorporation and In-doping to increase the electronic conductivity and concomitantly improve capacity retention and cycle life. It was found that the incorporation of In into SnO2 reduces the charge transfer resistance during cycling, prolonging life. It is also hypothesized that …

Go to article

Order Reduction Of Dae Models, John Hedengren, Thomas F. Edgar May 2016

Order Reduction Of Dae Models, John Hedengren, Thomas F. Edgar

Faculty Publications

This report outlines a technique for the order reduction of differential algebraic equations (DAEs). The order reduction is accomplished in two steps. First, algebraic states are partitioned into successive implicit sets of variables and equations by reconstructing the sparsity pattern into lower triangular block form. Second, proper orthogonal decomposition (POD) is used to reduce the number of differential states. As a test case for the theory, a dynamic binary distillation column model is analyzed with the generalized approach. The index 1 DAE model of 52 differential and 178 algebraic states is reduced to an ODE model of 26 differential states.

Go to article

Moving Horizon Estimation For An Industrial Gas Phase Polymerization Reactor, Jasmeer Ramhal, Kenneth V. Allsford, John Hedengren Apr 2016

Moving Horizon Estimation For An Industrial Gas Phase Polymerization Reactor, Jasmeer Ramhal, Kenneth V. Allsford, John Hedengren

Faculty Publications

A large-scale set of differential and algebraic equations (DAEs) is used to model and control an industrial gas phase polymerization reactor. Moving horizon estimation, preceding the nonlinear control optimization, provides an estimate of the current states and unmeasured disturbances. MHE is compared to Implicit Dynamic Feedback (IDFTM)*. With MHE, there is improved estimation of unmodeled disturbances in the UNIPOLTM** polyethylene plant. The polymerization model is converted to algebraic equations by orthogonal collocation and solved with the MHE objective function in a simultaneous optimization. NOVATM, an active-set sparse NLP solver, is used to converge …

Go to article

Protein Synthesis Directly From Pcr: Progress And Applications Of Cell-Free Protein Synthesis With Linear Dna, Song-Min Schinn, Andrew Broadbent, William T. Bradley, Bradley Charles Bundy Apr 2016

Protein Synthesis Directly From Pcr: Progress And Applications Of Cell-Free Protein Synthesis With Linear Dna, Song-Min Schinn, Andrew Broadbent, William T. Bradley, Bradley Charles Bundy

Faculty Publications

A rapid, versatile method of protein expression and screening can greatly facilitate the future development of therapeutic biologics, proteomic drug targets and biocatalysts. An attractive candidate is cell-free protein synthesis (CFPS), a cell-lysate-based in vitro expression system, which can utilize linear DNA as expression templates, bypassing time-consuming cloning steps of plasmid-based methods. Traditionally, such linear DNA expression templates (LET) have been vulnerable to degradation by nucleases present in the cell lysate, leading to lower yields. This challenge has been significantly addressed in the recent past, propelling LET-based CFPS as a useful tool for studying, screening and engineering proteins in a …

Go to article

A Continuous Formulation For Logical Decisions In Differential Algebraic Systems Using Mathematical Programs With Complementarity Constraints, Kody M. Powell, Ammon N. Eaton, John Hedengren, Thomas F. Edgar Mar 2016

A Continuous Formulation For Logical Decisions In Differential Algebraic Systems Using Mathematical Programs With Complementarity Constraints, Kody M. Powell, Ammon N. Eaton, John Hedengren, Thomas F. Edgar

Faculty Publications

This work presents a methodology to represent logical decisions in differential algebraic equation simulation and constrained optimization problems using a set of continuous algebraic equations. The formulations may be used when state variables trigger a change in process dynamics, and introduces a pseudo-binary decision variable, which is continuous, but should only have valid solutions at values of either zero or one within a finite time horizon. This formulation enables dynamic optimization problems with logical disjunctions to be solved by simultaneous solution methods without using methods such as mixed integer programming. Several case studies are given to illustrate the value of …

Go to article

A Continuous Formulation For Logical Decisions In Differential Algebraic Systems Using Mathematical Programs Of Complementarity Constraints, Kody Powell, Ammon N. Eaton, John Hedengren, Thomas F. Edgar Mar 2016

A Continuous Formulation For Logical Decisions In Differential Algebraic Systems Using Mathematical Programs Of Complementarity Constraints, Kody Powell, Ammon N. Eaton, John Hedengren, Thomas F. Edgar

Faculty Publications

This work presents a methodology to represent logical decisions in differential algebraic equation simulation and constrained optimization problems using a set of continuous algebraic equations. The formulations may be used when state variables trigger a change in process dynamics, and introduces a pseudo-binary decision variable, which is continuous, but should only have valid solutions at values of either zero or one within a finite time horizon. This formulation enables dynamic optimization problems with logical disjunctions to be solved by simultaneous solution methods without using methods such as mixed integer programming. Several case studies are given to illustrate the value of …

Go to article

Thermal Transport Properties Of Dry Spun Carbon Nanotube Sheets, Heath E. Misak, James L. Rutledge, Eric D. Swenson, Shankar Mall Feb 2016

Thermal Transport Properties Of Dry Spun Carbon Nanotube Sheets, Heath E. Misak, James L. Rutledge, Eric D. Swenson, Shankar Mall

Faculty Publications

The thermal properties of carbon nanotube- (CNT-) sheet were explored and compared to copper in this study. The CNT-sheet was made from dry spinning CNTs into a nonwoven sheet. This nonwoven CNT-sheet has anisotropic properties in in-plane and out-of-plane directions. The in-plane direction has much higher thermal conductivity than the out-of-plane direction. The in-plane thermal conductivity was found by thermal flash analysis, and the out-of-plane thermal conductivity was found by a hot disk method. The thermal irradiative properties were examined and compared to thermal transport theory. The CNT-sheet was heated in the vacuum and the temperature was measured with an …

Go to article

Voltammetric Analysis Of Mixtures Of Molten Eutectic Licl-Kcl Containing Lacl3 And Thcl4 For Concentration And Diffusion Coefficient Measurement, Zhong-Hang Wang, Devin Rappleye, Michael F. Simpson Jan 2016

Voltammetric Analysis Of Mixtures Of Molten Eutectic Licl-Kcl Containing Lacl3 And Thcl4 For Concentration And Diffusion Coefficient Measurement, Zhong-Hang Wang, Devin Rappleye, Michael F. Simpson

Faculty Publications

Several electrochemical techniques, including cyclic voltammetry (CV), chronopotentiometry-open circuit potential (CP-OCP), chronoamperometry (CA) and normal pulse voltammetry (NPV) were applied to the eutectic LiCl-KCl melt containing LaCl3 and ThCl4 at 773K. The dependence of diffusion coefficient of La(III) on concentration of LaCl3 was investigated by using CV, CP and CA. As the concentration of LaCl3 increases, the DLa(III) value obtained from CV gradually decreases, while the values derived from CA and CP exhibit a dome-shaped variation trend. In the LiCl-KCl-LaCl3-ThCl4 system, the diffusion coefficients of La(III) and Th(IV) are both approximately constant …

Go to article

Global Sensitivity Analysis For A Comprehensive Char Conversion Model In Oxy-Fuel Conditions, Troy Michael Holland, Thomas H. Fletcher Jan 2016

Global Sensitivity Analysis For A Comprehensive Char Conversion Model In Oxy-Fuel Conditions, Troy Michael Holland, Thomas H. Fletcher

Faculty Publications

Oxy-fired coal combustion is a promising potential carbon capture technology. Predictive CFD simulations are valuable tools in evaluating and deploying oxy-fuel and other carbon capture technologies either as retrofit technologies or for new construction. However, accurate predictive simulations require physically realistic submodels with low computational requirements. In particular, comprehensive char oxidation and gasification models have been developed that describe multiple reaction and diffusion processes. This work focuses on the sensitivity of a recent comprehensive char conversion code named CCK, which treats surface oxidation and gasification reactions as well as the processes such as film diffusion, pore diffusion, ash encapsulation, and …

Go to article

A Comparison Of Simple Global Kinetic Models For Coal Devolatilization With The Cpd Model, Andrew Richards, Thomas H. Fletcher Jan 2016

A Comparison Of Simple Global Kinetic Models For Coal Devolatilization With The Cpd Model, Andrew Richards, Thomas H. Fletcher

Faculty Publications

Simulations of coal combustors and gasifiers generally cannot incorporate the complexities of advanced pyrolysis models, and hence there is interest in evaluating simpler models over ranges of temperature and heating rate that are applicable to the furnace of interest. In this paper, six different simple model forms are compared to predictions made by the Chemical Percolation Devolatilization (CPD) model. The model forms included three modified one-step models, a simple two-step model, and two new modified two-step models. These simple model forms were compared over a wide range of heating rates (5000 to 106 K/s) at final temperatures up to …

Go to article

First Prev Next Last