Chemical Engineering Commons^™

A Promising Modification Of Pt Surfaces With Cnts For Decreasing Poisoning Impact In Direct Methanol Fuel Cells, Islam M. Al-Akraa Dr., Yaser M. Asal Mr, Aya A. Khalifa Ms.

Chemical Engineering

Direct methanol fuel cells (DMFCs) are clean energy sources that have many applications due to the high energy density of methanol as a fuel. However, this type of fuel cells (FCs) has limitations that are preventing it from being commercialized. One such limitation is the adsorption of intermediates such as CO into the surface of the Platinum (Pt) catalyst during methanol oxidation (MO) which deactivates its active sites, where the reaction is taking place, and leads to poisoning of the electrode over the long term. In this study, multi-walled carbon nanotubes (MWCNTs) have been introduced to the Pt-modified glassy carbon …

Novel Adsorbent For Industrial Wastewater Treatment Applications, Islam M. Al-Akraa, Ahmed Y. Zakaria Eng, Dalia A. Ali Eng, Hany A. Elazab Dr, Hoda A. Elsawy Dr

Chemical Engineering

In this study, the hydroxyapatite powder is investigated for both of methylene blue and thymol blue in aqueous solution. The physical and chemical properties of the adsorbent were evaluated systematically using the different techniques including Microsoft Excel programming, linear regression model and also the coefficient of determination. Batch adsorption experiments were conducted to determine the effect of contact time, solution pH, initial dye concentrations, and also the adsorbent dosage on adsorption. The adsorption kinetic parameters confirmed the better fitting of pseudo-second order kinetic model for both of methylene blue and thymol blue. The isotherm data of methylene blue and thymol …

Enhanced Electro-Oxidation Of Methanol At Pt-Au Nanocatalyst For Direct Methanol Fuel Cells, Islam M. Al-Akraa Dr., Yaser M. Asal Mr, Ahmad M. Mohammad Prof

Chemical Engineering

In this investigation, a Pt-Au nanocatalyst prepared by the coelectrodeposition of Pt (PtNPs) and Au (AuNPs) nanoparticles is assembled onto a glassy carbon (GC) electrode for efficient methanol oxidation (MO). Several molar ratios between PtNPs and AuNPs have been used and the corresponding catalytic activity towards MO is tracked. The Pt1:Au1 catalyst showed the highest catalytic activity (5 times higher oxidation peak current (Ip) and a 126 mV negative shift in the onset potential (Eonset) toward MO). The catalyst’s morphology, composition and activity are investigated and the ehancement mechanism is recognized.

A Simple And Effective Way To Overcome Carbon Monoxide Poisoning Of Platinum Surfaces In Direct Formic Acid Fuel Cells, Islam M. Al-Akraa Dr., Yaser M. Asal Mr, Sohair A. Darwish Ms

Chemical Engineering

A glassy carbon (GC) electrode modified with multi-walled carbon nanotubes (MWCNTs) and platinum nanoparticles (PtNPs), Pt/MWCNTs-GC, has been introduced for formic acid electro-oxidation (FAO). A similar loading of PtNPs has been conserved for a proper comparison between the Pt/MWCNTs-GC and the unmodified Pt/GC electrodes. The modification with MWCNTs could enhance the loading of PtNPs onto the GC electrode in a way that minimizes its agglomeration and increases its dispersion in the CNTs network. This not only increases the surface area exposed to the reaction but also interrupts the contiguity of the Pt active sites minimizing the adsorption of the poisoning …

Empirical Modeling Of Urea Synthesis Chemical Equilibria, Moustafa A. Soliman

Chemical Engineering

In this paper empirical formulas for the chemical equilibrium of reactions involved in urea synthesis are derived. Their accuracy is checked against data obtained from the application of Aspen Plus to a urea plant based on Stamicarbon technology. The accurate results obtained support their application in the simulation of the reactions involved in urea synthesis.

Approximate Analytical Solution For Mathematical Models Of Thermal Ignition And Non-Isothermal Catalytic Zero Order Reaction In A Spherical Geometry, Moustafa A. Soliman

Chemical Engineering

In this paper an approximate analytical solution for the Frank-Kamenetskii equation modeling thermal ignition without the depletion of the combustibles in a spherical annulus and non-isothermal zero order reaction in spherical catalyst particle is presented. The approximate solution is compared with the numerical solution and is in good agreement with the numerical solution. The approximate solution obtained is valid for all values of the distance parameter. Multiple solutions occur for some range of Frank-Kamenetskii parameter (λ). The multiplicity is infinite for the case of a solid sphere and λ=2.Interesting relation is obtained for λ at the turning points. For the …

Online Model Predictive Control Of A Nonisothermal And Nonisobaric Membrane Reactor For Water-Gas Shift Reaction Applications, Jacob Martin Douglas

Graduate Theses, Dissertations, and Problem Reports (ETD)

Online Model Predictive Control of a Nonisothermal and Nonisobaric Membrane Reactor for Water-Gas Shift Reaction Applications Jacob M. Douglas Modern hydrogen production units are tasked with producing the most hydrogen possible while dealing with flow variations caused by changing power demands. Classical methods for hydrogen production employing the water-gas shift reaction are governed by equilibrium limitations that take effect at high temperatures and high concentrations of H2 (Georgis, et al., 2014). The implementation of a membrane reactor with temperature control enables the hydrogen concentration and temperature to reach an equilibrium at a higher concentration of H2. Another challenge that is …

Confirmation Of Data-Driven Reservoir Modeling Using Numerical Reservoir Simulation, Al Hasan Mohamed Al Haifi

Graduate Theses, Dissertations, and Problem Reports (ETD)

Data driven reservoir modeling, also known as Top-Down Model (TDM), is an alternative to the traditional numerical reservoir simulation technique. Data driven reservoir modeling is a new technology that uses artificial intelligence and machine learning to build full-field reservoir models using field measurements (data - facts) instead of mathematical formulations that represent our current understanding of the physics of the fluid flow through porous media. TDM combines all field measurements into a comprehensive reservoir model to predict the production from each well in a field with multiple wells.

There are many opinions, speculations and criticism about not using the physics-based …

Development Of A Dynamic Model And Control System For Load-Following Operation Of Supercritical Pulverized Coal Power Plants, Parikshit S. Sarda

Graduate Theses, Dissertations, and Problem Reports (ETD)

Thermal power plants that have been designed to operate at their rated capacity are being forced to cycle their load and operate under low-load condition to meet changing load demands due to the increased penetration of renewables into the electric grid. The rapid load-following operation is leading to challenging control problems. The goal of this research is to develop dynamic model and control system for efficient load-following operation. The focus of this work is on supercritical pulverized coal (SCPC) power plants. The steady-state model is developed using Aspen Plus and Aspen Custom Modeler and then converted to a pressure-driven Aspen …

Design And Implementation Of Model Predictive Control Strategies For Improved Power Plant Cycling, Xin He

Graduate Theses, Dissertations, and Problem Reports (ETD)

Design and Implementation of Model Predictive Control Strategies for Improved Power Plant Cycling

Xin He

With the increasing focus on renewable energy sources, traditional power plants such as coal-fired power plants will have to cycle their load to accommodate the penetration of renewables into the power grid. Significant overshooting and oscillatory performance may occur during cycling operations if classical feedback control strategies are employed for plantwide control. To minimize the impact when power plants are operating away from their designed conditions, model-based optimal control strategies would need to be developed for improved power plant performance during cycling.

In this thesis, …

Designing Particle Tracking Software For A Theoretical Understanding Of Magnetic Janus Particle Aggregation, Thomas W. Long

Dissertations and Theses

Magnetic Janus particles are spherical colloids covered with a thin magnetic cap on one half of their surface. The asymmetric magnetic material gives the particles a magnetic dipole shifted away from the center of mass of the particle. The magnetic dipole either points perpendicular (axially-shifted FexOy caps) or parallel (radially-shifted (Co/Pd)x multilayered particles) to the shift vector. When a magnetic field is applied to a system of magnetic Janus particles, the particles aggregate into chains aligned with the magnetic field. The rate of aggregation is of theoretical and practical interest and the focus of the thesis.

Optically studying samples of …

Literature Survey Of Wet-Waste And Hydrothermal Carbonization System: A Comparative Evaluation, Ramat Olaide Yusuf

Dissertations and Theses

This thesis describes the process of Hydrothermal carbonization and a comparative assessment on recent work done on the process using different feedstocks such as Raw Apple (RA), Apple chip pomace (ACP), apple juice pomace (AJP), grape pomace (GP), macadamia nut-shell (MNS), Sewage Sludge (SS), Poultry Litter (PL) and Grape Marc (GM). The data obtained from the literature survey was compared with the data obtained by the CCL team on the SWPS gasifier (HTC of poultry litter) to obtain how carbon conversion efficiency, syngas composition, thermal efficiency, char production rate, gas production rate and energy utilization vary with carbonization process conditions, …

Investigation Of The Synthesis And Optoelectronic Properties Of Ultrasmall Cdse Quantum Dots, Megan Webster

Dissertations and Theses

Traditional, or 1^st generation, solar cells have a theoretical upper limit of 33% power conversion efficiency based on the thermodynamic limitation of the single p-n junction cell design. This limitation is known as the Shockley-Queisser limit and methods to design solar cells to circumvent it have been creative, with a significant part of the field focused on quantum dot (QD) based systems. With theoretical efficiencies ranging between 44 and 67% for one sun concentration, QD solar cell designs are clearly superior to the limits of 1^st generation solar cells. However, maximum achieved efficiencies for QD-based designs are far …

Microfluidic Study Of Gravity-Driven Drainage And Coalescence Of Aqueous Two Dimensional Foams, Justin D. Heftel

Dissertations and Theses

Foams, a two-phase dispersion, are staples of the cosmetic, personal care, petroleum, pharmaceutical, and other industries. Central to these applications is the stability of the dispersion against separation. Foams break down by two mechanisms: the first is bubble coalescence, which is driven by the gravity drainage of the continuous phase. The drainage acts to push the bubbles against each other, and leads to the formation of thin lamellae, which break and cause the coalescence. The second is the mass transfer of the dispersed phase through the continuous phase, which is caused by the difference in pressures between the bubbles and …

Gas Hold-Up Measurements In 0.3 M Diameter Bubble Column: Effect Of Electrolytes, Heber Blanco De Brand

Dissertations and Theses

The present work reports the axial, radial and temporal gas hold-up profiles in a 0.3 m diameter batch bubble column using a pair of Wire Mesh Sensors and six pressure transducers.

Elucidation Of The Catalytic Partial Oxidation Of Methane Utilizing The One-Of-A-Kind Catalytic Shock Tube Technique, Robyn E. Smith

Dissertations and Theses

The mechanism for the catalytic partial oxidation of methane has been debated in scientific literature for over 20 years. This is a seemingly simple reaction producing CO, CO₂, H₂ and H₂O through either partial oxidation followed by complete oxidation or complete oxidation followed by reforming steps. What is happening when the reaction is allowed to occur in an environment absent of transport limitations, absent of temperature gradients and temperature changes, absent of boundary layers must be understood and, until now, has yet to be achieved in one experimental technique.

A novel method using a one …

Development Of A Sustainability Evaluation And Control Framework For Chemical Processes, Shuyun Li

Graduate Theses, Dissertations, and Problem Reports (ETD)

Industry, government, and society have begun to shift from economic stand-alone focus to the inclusion of sustainability in the decision-making process. This shift can be attributed to the growing environmental and social awareness that makes consumers and stakeholders not only care about product quality and cost, but also products and processes that minimize the environmental impact and conserve natural resources. As a result, some progress has been made in recognizing and understanding the challenges of sustainable development, which helps evaluating the sustainability performance of a specific process/product. In particular, sustainability assessment tools and methodologies have been developed to help the …

The Cooperative Effects Of Channel Length-Bias, Width Asymmetry, Gradient Steepness, And Contact-Guidance On Fibroblasts’ Directional Decision Making, Quang Long Pham

Dissertations

Cell migration in complex micro-environments, that are similar to tissue pores, is important for predicting locations of tissue nucleation and optimizing scaffold architectures. Firstly, how fibroblast cells - relevant to tissue engineering, affect each other’s directional decisions when encountered with a bifurcation of different channel lengths was investigated. It was found that cell sequence and cell mitosis influence the directional choices that the cells made while chemotaxing. Specifically, the fibroblasts chose to alternate between two possible paths - one longer and the other shorter - at a bifurcation. This finding was counter-intuitive given that the shorter path had a steeper …

Experimental And Numerical Characterization Of Multiphase Subsurface Oil Release, Feng Gao

Dissertations

Subsurface oil release is commonly encountered in the natural environment and engineering applications and has received the substantial attention of researchers after the disastrous Deepwater Horizon Blowout oil spill in 2009. The main focus on the present research is to systematically study the hydrodynamics of underwater oil jet under a variety of conditions, including the effect of dispersant and different gas to oil ratios (GOR) by using experimental measurement as well as a Computational Fluid Dynamics (CFD) approach, from which the measured turbulent characteristics (e.g., velocity, turbulent kinetic energy, turbulence dissipation rate, etc.) of underwater oil jet are thoroughly examined …

Overcoming Conventional Modeling Limitations Using Image- Driven Lattice-Boltzmann Method Simulations For Biophysical Applications, Olufemi E. Kadri

Dissertations

The challenges involved in modeling biological systems are significant and push the boundaries of conventional modeling. This is because biological systems are distinctly complex, and their emergent properties are results of the interplay of numerous components/processes. Unfortunately, conventional modeling approaches are often limited by their inability to capture all these complexities. By using in vivo data derived from biomedical imaging, image-based modeling is able to overcome this limitation.

In this work, a combination of imaging data with the Lattice-Boltzmann Method for computational fluid dynamics (CFD) is applied to tissue engineering and thrombogenesis. Using this approach, some of the unanswered questions …