Digital Commons Network^™

In-Situ Electrochemical Analysis Of Microbial Activity, Ariane L. Martin, Pongsarun Satjaritanun, Sirivatch Shimpalee, Blake A. Devivo, John Weidner, Scott Greenway, J. Michael Henson, Charles E. Turick

Faculty Publications

Microbes have a wide range of metabolic capabilities available that makes them industrially useful organisms. Monitoring these metabolic processes is a crucial component in efcient industrial application. Unfortunately, monitoring these metabolic processes can often be invasive and time consuming and expensive, especially within an anaerobic environment. Electrochemical techniques, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) ofer a non-invasive approach to monitor microbial activity and growth. EIS and CV were used to monitor Clostridium phytofermentans, an anaerobic and endospore-forming bacterium. C. phytofermentans ferments a wide range of sugars into hydrogen, acetate, and ethanol as fermentation by-products. For this …

Performance Comparison Of Low Temperature And Chemical Absorption Carbon Capture Processes In Response To Dynamic Electricity Demand And Price Profiles, Seyed Mostafa Safdarnejad, John Hedengren, Kody M. Powell

Faculty Publications

Current projections to the year 2050 reveal that fossil fuels will remain the main source of energy generation. To achieve the target limits of carbon dioxide emission, set by national and international policies, carbon capture will play a key role. Modeling and optimization of various carbon capture technologies such as pre-combustion, oxy-fuel, and post-combustion, when integrated with coal-fired power plants, have been researched extensively in literature. Research on the integration of power generation with capture technologies regarding comparisons between the different schemes in response to dynamic inputs is lacking. This work provides a comparison between a low temperature carbon capture …

Statistically Guided Synthesis Of Mov- Based Mixed Oxide Catalysts For Ethane Partial Oxidation, Juan D. Jimenez, Kathleen Mingle, Teeraya Bureerug, Cun Wen, Jochen Lauterbach

Faculty Publications

The catalytic performance of Mo8V2Nb1-based mixed-oxide catalysts for ethane partial oxidation is highly sensitive to the doping of elements with redox and acid functionality. Specifically, control over product distributions to ethylene and acetic acid can be afforded via the specific pairing of redox elements (Pd, Ni, Ti) and acid elements (K, Cs, Te) and the levels at which these elements are doped. The redox element, acid element, redox/acid ratio, and dopant/host ratio were investigated using a three-level, four-factor factorial screening design to establish relationships between catalyst composition, structure, and product distribution for ethane partial oxidation. Results show that the balance …

Statistically Guided Synthesis Of Mov-Based Mixed-Oxide Catalysts For Ethane Partial Oxidation, Juan D. Jimenez, Kathleen Mingle, Teeraya Bureerug, Cun Wen, Jochen A. Lauterbach

Faculty Publications

The catalytic performance of Mo8V2Nb1-based mixed-oxide catalysts for ethane partial oxidation is highly sensitive to the doping of elements with redox and acid functionality. Specifically, control over product distributions to ethylene and acetic acid can be afforded via the specific pairing of redox elements (Pd, Ni, Ti) and acid elements (K, Cs, Te) and the levels at which these elements are doped. The redox element, acid element, redox/acid ratio, and dopant/host ratio were investigated using a three-level, four-factor factorial screening design to establish relationships between catalyst composition, structure, and product distribution for ethane partial oxidation. Results show that the balance …

Hydrogels For Cell Delivery, Esmaiel Jabbari

Faculty Publications

No abstract provided.

Arrhenius Rate Chemistry-Informed Inter-Phase Source Terms (Arciist), Matthew J. Schwaab, Robert B. Greendyke, Bryan J. Steward

Faculty Publications

Currently, in macro-scale hydrocodes designed to simulate explosive material undergoing shock-induced ignition, the state of the art is to use one of numerous reaction burn rate models. These burn models are designed to estimate the bulk chemical reaction rate. Unfortunately, these burn rate models are largely based on empirical data and must be recalibrated for every new material being simulated. We propose that the use of Arrhenius Rate Chemistry-Informed Interphase Source Terms (ARCIIST) in place of empirically derived burn models will improve the accuracy for these computational codes. A reacting chemistry model of this form was developed for the cyclic …

Integrated Scheduling And Control In Discrete-Time With Dynamic Parameters And Constraints, Logan Beal, Damon Petersen, David R. Grimsman, Sean Warnick, John Hedengren

Faculty Publications

Integrated scheduling and control (SC) seeks to unify the objectives of the various layers of optimization in manufacturing. This work investigates combining scheduling and control using a nonlinear discrete-time formulation, utilizing the full nonlinear process model throughout the entire horizon. This discrete-time form lends itself to optimization with time-dependent constraints and costs. An approach to combined SC is presented, along with sample pseudo-binary variable functions to ease the computational burden of this approach. An initialization strategy using feedback linearization, nonlinear model predictive control, and continuous-time scheduling optimization is presented. The formulation is applied with a generic continuous stirred tank reactor …

Gekko Optimization Suite, Logan Beal, Daniel Hill, Ronald Abraham Martin, John Hedengren

Faculty Publications

This paper introduces GEKKO as an optimization suite for Python. GEKKO specializes in dynamic optimization problems for mixed-integer, nonlinear, and differential algebraic equations (DAE) problems. By blending the approaches of typical algebraic modeling languages (AML) and optimal control packages, GEKKO greatly facilitates the development and application of tools such as nonlinear model predicative control (NMPC), real-time optimization (RTO), moving horizon estimation (MHE), and dynamic simulation. GEKKO is an object-oriented Python library that offers model construction, analysis tools, and visualization of simulation and optimization. In a single package, GEKKO provides model reduction, an object-oriented library for data reconciliation/model predictive control, and …

Synthesis-Structure-Activity Relationships In Co3o4 Catalyzed Co Oxidation, Kathleen Mingle, Jochen A. Lauterbach

Faculty Publications

In this work, a statistical design and analysis platform was used to develop cobalt oxide based oxidation catalysts prepared via one pot metal salt reduction. An emphasis was placed upon understanding the effects of synthesis conditions, such as heating regimen and Co2+ concentration on the metal salt reduction mechanism, the resultant nanomaterial properties (i.e., size, crystal structure, and crystal faceting), and the catalytic activity in CO oxidation. This was accomplished by carrying out XRD, TEM, and FTIR studies on synthesis intermediates and products. Additionally, high-throughput experimentation was employed to study the performance of Co3O4 oxidation catalysts over a wide range …

Marangoni Flows During Nonsolvent Induced Phase Separation, Douglas R. Tree, Tatsuhiro Iwama, Kris T. Delaney, Joshua Lee, Glenn H. Fredrickson

Faculty Publications

Motivated by the much discussed, yet unexplained, presence of macrovoids in polymer membranes, we explore the impact of Marangoni flows in the process of nonsolvent induced phase separation. Such flows have been hypothesized to be important to the formation of macrovoids, but little quantitative evidence has been produced to date. Using a recently developed multifluid phase field model, we find that roll cells indicative of a solutal Marangoni instability are manifest during solvent/nonsolvent exchange across a stable interface. However, these flows are weak and subsequently do not produce morphological features that might lead to macrovoid formation. By contrast, initial conditions …

New Flow Assurance System With High Speed Subsea Fiber Optic Monitoring Of Pressure And Temperature, John Hedengren, David Brower, J. Conrad Wilson, Geoff High, Karl Witherow

Faculty Publications

Subsea production control systems are instrumented to constantly monitor flowline pressure and temperature at key locations to prevent plugging and introduce mitigating control strategies. New fiber optic sensors with ruggedized construction and non-electrical components are subjected to accelerated aging tests and deployed in several installations with long service life. An overview of current progress with fiber optic technology is provided for fatigue monitoring, temperature, pressure, and strain sensing. Recent developments include improved service life, novel bonding methods, pipeline sensor station improvements, sensor calibration, and long-term fatigue analysis.

The latest advancements are validated on multiple installations on a subsea tieback in …

A Novel Supercritical Co2-Based Decellularization Method For Maintaining Scaffold Hydration And Mechanical Properties, Michael A. Matthews, Tarek Shazly, Rachel M. Handleton, Dominic M. Casali

Faculty Publications

Decellularized tissues are commonly utilized as tissue engineering scaffolds. Decellularization by extended exposure to aqueous detergents can damage the microstructure or deposit cytotoxic residue. Supercritical carbon dioxide (scCO2) has been proposed for decellularization, but reportedly causes dehydration and scaffold embrittlement.

Presented herein is a novel decellularization method that preserves matrix hydration state and mechanical properties. Over 97% of the water in porcine aorta is maintained by presaturating scCO2 with water; however, complete decellularization was not attained by any process utilizing only scCO2. Instead, a novel hybrid method is presented that combines a brief (48 h) exposure of tissue to aqueous …

Characterization Of Pyrolysis Products From Fast Pyrolysis Of Live And Dead Vegetation Native To The Southern United States, Mohammad-Saeed Safdari, Mahmood Rahmati, Elham Amini, Joel E. Howarth, Jansen P. Berryhill, Mark Dietenberger, David R. Weise, Thomas H. Fletcher

Faculty Publications

Prescribed burning (controlled burning) is used to decrease accumulation of combustible materials and reduce impact of uncontrolled wildland fires. Prescribed fires are often used to burn undergrowth in Southern forests of the United States. In order to improve prescribed fire application, accomplish desired fire effects, and limit potential runaway fires, an improved understanding of the fundamental processes related to combustion of heterogeneous fuel beds of live and dead fuels is needed. The initial processes of combustion involve pyrolysis and ignition. During this research, fast pyrolysis of 14 live and dead (biomass) plant species which are native to the Southern United …

Effects Of Ag Promotion And Preparation Method On Cobalt Fischer- Tropsch Catalysts Supported On Silica-Modified Alumina, Mahmood Rahmati, Baiyu Huang, Landon M. Schofield, Thomas H. Fletcher, Brian F. Woodfield, William C. Hecker, Calvin H. Bartholomew, Morris D. Argyle

Faculty Publications

A series of silver-promoted, 20 wt% cobalt Fischer-Tropsch synthesis (FTS) catalysts supported on an alumina modified with 5 wt% silica were prepared using two methods: traditional incipient wetness impregnation (IWI) and a new solvent deficient precipitation (SDP) technique. Catalysts containing silver promoter concentrations of 0.3, 0.6, 1.2, and 2.5 wt% were prepared using each of the two methods. Silver improved the reducibility of the cobalt significantly, lowering reduction temperatures by up to 100 C, and increasing the extent of reduction by up to 35%. Further, in both preparation methods, changing the silver loading altered the cobalt dispersion. The smallest Co …

Lab-Scale Observations Of Flame Attachment On Slopes With Implications For Firefighter Safety Zones, Jonathan R. Gallacher, Brad Ripa, Bret W. Butler, Thomas H. Fletcher

Faculty Publications

The Coanda effect is the phenomenon in which a jet entering quiescent fluid attaches to a nearby solid object due to inhibited entrainment of ambient fluid near the solid. Little is known about the influence of the Coanda effect on wildland fire behavior. Specifically, there is a lack of knowledge regarding how the flame attachment on slopes influences firefighter safety zone considerations in rugged terrain. This paper presents results for small-scale n-heptane pool fire experiments near a slope, showing how flame shape and heat flux are influenced by slope angle, slope boundary condition and distance from flame base. Flames near …

Effect Of Different Alumina Supports On Performance Of Cobalt Fischer-Tropsch Catalysts, Thomas H. Fletcher

Faculty Publications

Four identically-prepared 20 wt% cobalt/0.15 wt% ruthenium Fischer-Tropsch catalysts, supported on different aluminas, were synthesized by incipient wetness impregnation, characterized, and compared based on their performance under standard Fischer-Tropsch synthesis conditions. Three alumina supports were obtained from commercial sources (Sasol, St. Gobain, and Alfa Aesar), while the fourth was made using a published technique that included 5 wt% silica. The silica-stabilized alumina catalyst produced superior Fischer-Tropsch rates of 49 mmol CO/gcat h, compared to the other catalysts on the commercial supports with rates of 26–39 mmol CO/gcat h. The improved performance of the silica-stabilized alumina support compared to the commercially …

Formation Of Deposits From Heavy Fuel Oil Ash In An Accelerated Deposition Facility At Temperatures Up To 1219 °C, Robert Laycock, Thomas H. Fletcher

Faculty Publications

Some industrial gas turbines are currently being fired using heavy fuel oil, which contains a small percentage of inorganic material that can lead to fouling and corrosion of turbine components. Deposits of heavy fuel oil ash were created in the Turbine Accelerated Deposition Facility (TADF) at Brigham Young University under gas turbine-related conditions. Ash was produced by burning heavy fuel oil in a downward-fired combustor and collecting the ash from the exhaust stream. This ash was then introduced into the TADF and entrained in a hot gas flow that varied from 1101 °C to 1219 °C. Sulfur dioxide was introduced …

Fire Behavior In Chaparral–Evaluating Flame Models With Laboratory Data, David R. Weise, Thomas H. Fletcher, Wesley Cole, Shankar Mahalingam, Xiangyang Zhou, Lulu Sun, Jing Li

Faculty Publications

Flame and mass loss data for chaparral, a mixture of shrub plants from the Mediterranean climate zone of southwestern North America, from five previously reported experiments were used to evaluate several published models relating flame characteristics to mass loss and heat release rates. These data are unique with fuel moisture content ranging from 0.36 to 0.94 (dry basis); the study used mass loss rates which included water loss. Fit of the data to Froude number correlations developed by Albini, Byram, Nelson and Thomas and heat release rate—flame length correlations by Heskestad, Zukoski, and Yuan/Cox for axisymmetric and line fires were …

Development Of Bioreactors For Comparative Study Of Naturalattenuation, Biostimulation, And Bioaugmentation Ofpetroleum-Hydrocarbon Contaminated Soil, Mohammad-Saeed Safdari, Hamid-Reza Kariminia, Mahmood Rahmati, Farhad Fazlollahi, Alexandra Polasko, Shaily Mahendra, W Vincent Wilding, Thomas H. Fletcher

Faculty Publications

Bioremediation of soil and groundwater sites contaminated by petroleum hydrocarbons is known as a technically viable, cost-effective, and environmentally sustainable technology. The purpose of this study is to investigate laboratory-scale bioremediation of petroleum-hydrocarbon contaminated soil through development of eight bioreactors, two bioreactors for each bioremediation mode. The modes were: (1)natural attenuation (NA); (2) biostimulation (BS) with oxygen and nutrients; (3) bioaugmentation (BA)with hydrocarbon degrading isolates; (4) a combination of biostimulation and bioaugmentation (BS-BA). Total petroleum hydrocarbons (TPH) mass balance over the bioreactors showed about 2% of initial20,000 mg kg-soil−1TPH was removed by advection due to synthetic groundwater which was flow-ing …