Catalysis and Reaction Engineering Commons^™

Voltage-Related Power Quality Issues And Impacts On Distribution Networks With Sensitive Loads - A Review, Godwin Elinazi Mnkeni, Jackson Justo, Aviti Thadei Mushi, Bakari M. M. Mwinyiwiwa

Tanzania Journal of Engineering and Technology (TJET)

Voltage disturbances are the most important power quality (PQ) complications that customers and power utilities face in this smart era. The growing adoption of sophisticated electronic equipment and integration of renewable energy sources (RES) into power grids has increased the susceptibility of power distribution networks (PDNs) to voltage sags, swells, interruptions, flicker, and voltage imbalance. These disturbances, mainly caused by upstream faults, switching operations, and RES integration, compromise voltage PQ and system reliability. Consequently, they accelerate equipment degradation, increase electronic waste (e-waste), raise reactive power demand and maintenance costs, increase power losses, and impose substantial economic losses on customers and …

Effect Of Concentration And Temperature Of Tio2-Al2o3 Hybrid Nanofluid On The Corrosion Rate Of Aluminum Radiator, Ratna Monasari, Rizky Maulana Ramadhan, Nike Nur Farida, Ahmad Hanif Firdaus, Supa Kusuma Aji, Yuniarto Agus Winoko, Rizkyansyah Alif Hidayatullah

Journal of Mechanical Engineering Science and Technology (JMEST)

Corrosion of aluminum radiators can reduce cooling system reliability and shorten service life in automotive applications. This study examines the effect of TiO₂-Al₂O₃ hybrid nanofluid concentration and temperature on the corrosion rate of commercially available aluminum radiator material. Hybrid nanoparticles with a TiO₂-Al₂O₃ mass ratio of 50:50 were dispersed in distilled water at concentrations of 0.6 wt.%, 0.8 wt.%, and 1.0 wt.%. Corrosion behavior was evaluated using a 14-day accelerated immersion test at 60°C and 80°C, and the corrosion rate was determined using the gravimetric mass loss method. The results …

Material Degradation And Analysis Of N-Doped Graphene/Mof Nanocatalysts For Orr In Electrochemical Energy Systems, Niladri Talukder

Dissertations

The development of advanced electrochemical energy conversion and storage systems is crucial for achieving sustainable energy security. As alternatives to precious metal-based catalysts in electrochemical systems, especially for the oxygen reduction reaction (ORR), Nitrogen-doped Graphene with Metal-organic Frameworks (N-G/MOF) nanocatalysts have shown exceptional promise in recent years. This research advances the understanding of N-G/MOF nanocatalysts by systematically examining their structural features, degradation traits, correlated performance losses, and other aspects related to catalytic activities.

First, nitrogen-doped graphene (N-G) nanocatalysts were thoroughly investigated, resolving their physical properties, the influence of synthesis parameters, molecular-level material structures, and chemical and electronic structural details of …

Control Of Ferroelectric And Dielectric Properties Of Undoped, Fe, And Nb-Doped Single-Crystalline (001) Oriented Pb (Zr0.5ti0.5) O3 Thin Films, Mahamudu H. Mtebwa

Tanzania Journal of Engineering and Technology (TJET)

While several factors that influence the properties of ferroelectric devices have been extensively studied in bulk ceramics and polycrystalline thin films, limited is known about the same on single crystalline thin films which have great potential in memory and energy applications. This knowledge gap is largely due to the limited availability of substrates with lattice parameters suitable for supporting high-quality epitaxial growth. In this study, undoped, Fe-doped, and Nb-doped (001)-oriented Pb(Zr₀.₅Ti₀.₅)O₃ thin films were deposited using pulsed laser deposition, each with a SrRuO₃ bottom electrode and a PrScO₃ substrate. The doping concentration used is 1% for both Fe and Nb. …

Comprehensive Review Of Sensible Thermal Storage Systems For Cooking Applications, Anna K. Shariishoy

Tanzania Journal of Engineering and Technology (TJET)

This paper reviewed the sensible thermal storage systems specifically designed for cooking applications. The review focuses on the characteristics of storage materials, their practical applications, and the overall performance of the systems. The review consolidated an array of experimental and numerical research published across various sources such as journals, conferences, books, online resources, and professional reports. A systematic review is used to reach the conclusion of this paper. Significant findings from this study include the wide range of storage capacities attained from small-scale systems that can store ~1–5 MJ of energy for a single meal to bigger systems that can …

Predicting The Influence Of Aggregate Size And Distribution On Cementitious Concrete Properties: A Review, Innocent J. Macha

Tanzania Journal of Engineering and Technology (TJET)

Cement concrete has been in use for centuries as one of the primary construction materials. Its demand in the construction industry is expected to continue for several centuries before the full development of alternative products. However, one of the main areas of research interest is understanding how its constituents can be tailored to make its properties predictable to reduce risks associated with structural failures, reconstruction and reduced durability. These hindrances associated with cementitious concrete result from several attributes, including constituent material characteristics, mixing ratios and workmanship. Understanding the predictability of cement concrete properties requires computer modelling tools to provide reliable …

Optimizing The Processing Temperature For Synthesis Of Silver Nanoparticles Within Cellulose-Wool Keratin Supramolecular Matrix Using Butylmethylimmidazolium Chloride Ionic Liquid, Ngesa E. Mushi

Tanzania Journal of Engineering and Technology (TJET)

To date, the synthesis of silver nanoparticles on the surface of cellulose and wool keratin biopolymer, while dissolved in ionic liquid, is attractive because of its biomedical potential. However, the optimal processing temperature for the nanoparticle formation is unclear. The previously reported temperature of approximately 120°C gives unpredictable results. The current study employs a combination of 50% cellulose and 50% keratin, along with 69 mg of silver chloride, in Butylmethylimidazolium Chloride BMImCl ionic liquid, using a single-pot process to produce a supramolecular film via non-derivatized mechanochemical interactions. The primary objective is to experimentally establish the processing temperature to achieve stable …

Cyclic Combustion Pressure Dynamics Of A Diesel Engine Operating On Waste Frying Oil Biodiesel Blends Using Wavelets, Shady Elmozy, Ahmed Khaira Dr., Elshenawy Elshenawy Prof. Dr., Ali Mohamed Dr., Medhat Elkelawy Prof. Dr,

Journal of Engineering Research

This paper investigates the cyclic combustion pressure dynamics of a single-cylinder diesel engine burning waste frying oil biodiesel blends, employing statistical analysis and continuous wavelet transform (CWT) to evaluate combustion stability. Experiments were conducted at a constant engine load (90%) and speed (1500 rpm), with in-cylinder pressure data collected over 400 consecutive cycles for conventional diesel (RD) and biodiesel blends (UB10, UB30, UB50). Results demonstrate that biodiesel blends marginally reduce average peak cylinder pressure (PP) by 0.3–3.8% while lowering PP variability, evidenced by declining coefficients of variation (COV-PP: 1.27–1.48%), attributed to biodiesel’s elevated viscosity promoting consistent fuel-air mixing. Conversely, mean …

Combustion Characteristics And Cycle-To-Cycle Variations In A Diesel Generator Fueled With Used Frying Oil Biodiesel Blends, Shady Elmozy, Ahmad Khira Dr., E. A. El Shenawy Prof. Dr., Medhat Elkelawy Prof. Dr, Eng.

Journal of Engineering Research

This paper investigates the combustion characteristics and cycle-to-cycle variations in a stationary direct-injection diesel generator fueled with biodiesel derived from used frying oil (UFO) blended with conventional diesel. Used frying oil methyl ester (UFOME), referred to as UB100, was produced through a single-step alkali transesterification process and blended with diesel fuel in varying proportions (UB10, UB20, UB30, UB40, and UB50). Experiments were conducted on a single-cylinder, naturally aspirated diesel engine operating at a constant speed of 1500 rpm under five different load conditions: 0%, 25%, 50%, 75%, and 90%. In-cylinder pressure data from 400 consecutive cycles were analyzed to determine …

Ultrafast Laser Surface Structuring For Wettability Control On Copper, Akshay Arvind Nagvenkar

All Theses

Wettability is a crucial surface property influencing various phenomena, including heat transfer, cell adhesion, and corrosion. Engineering devices can achieve superior performance by precisely manipulating surface wettability. As a result, extensive research has focused on developing surfaces that exhibit either extreme water attraction (superhydrophilic) or strong water repellency (superhydrophobic). Tailoring surface wettability paves the way for numerous applications, such as drag reduction in marine vessels, controlled drug delivery, efficient water collection, advanced liquid transport systems, oil-water separation, anti-corrosion coatings, friction reduction, and self-cleaning materials. Ultrafast laser surface structuring is a promising approach for engineering multifunctional surfaces, effectively modifying material properties …

Assessment Of Factors Contributing On Early Rotting Of Chromated Copper Arsenate Treated Utility Power Distribution Wood Poles In Tanzania, Innocent J. Macha

Tanzania Journal of Engineering and Technology (TJET)

The study aimed to assess the factors contributing to the premature decay of Chromated Copper Arsenate (CCA) treated utility power distribution wooden poles in Tanzania. Deteriorated poles samples from various regions in Tanzania were analyzed using handheld X-ray spectrometry to quantify the retention of CCA preservative chemicals. The ages of these poles were estimated based on annual growth rings. The findings indicated that premature failure of CCA treated wooden poles is attributed to an imbalance in the chemical composition of the preservative solution. The study found that CuO retention in most samples ranged between 10-18 kg/m3, significant lower that the …

Optimization And Dft Study For Boosted Electooxidation Of Formic Acid At Niox Modified Pt Using Urea Derivatives As Blending Fuels, Aya Saada

Biochemical Engineering

This paper addresses the enhancement of formic acid electrooxidation (FAO) at Pt and Pt-NiOx nanoparticles based-catalysts assisted with urea derivatives as blending fuels. Blending formic acid with various ratios of urea derivatives showed noticeable enhancements of FAO as demonstrated by a favorable negative shift of its onset potential (Eonset) and increase of its peak current density concurrently with suppression of the amount of CO poisoning reaction intermediate. Among all the used derivatives, phenyl urea (PU) showed superior enhancing effect towards the direct FAO with a minimal CO formation together with a favorable negative shift of Eonset by 150 mV. The …

Integrating Medical Plastic Waste Pyrolysis And Circular Economy For Environmental Sustainability, Attia Attia, Mohamed Bassyouni Prof., Reem Nasser Eng., Moataz El-Bagoury Eng., Islam Shaker Eng., Yasser Elhenawy Prof., Dina Aboelela Dr.

Biochemical Engineering

A critical assessment of pyrolysis technologies and reactor designs was discussed, highlighting various reactor configurations. This study explored the influence of catalysts, temperature, heating rate, and residence time on the pyrolysis process, and addressed their effects on product distribution and composition. Safety considerations and strategies for mitigating the potential environmental impacts of pyrolysis were presented. Comparative analyses of the environmental impacts of traditional waste disposal methods versus pyrolysis-based approaches provided insights into the potential reduction of greenhouse gas emissions and other pollutants. The circular economy approach was explored in the context of medical plastic waste pyrolysis. The potential for closing …

Microwave-Assisted Reduction Of Critical Metal Oxides From E-Waste Mixture, Kurundu Shavinka Jayasekera

Graduate Theses, Dissertations, and Problem Reports (ETD)

The efficient recovery of critical metals such as tantalum (Ta), manganese (Mn), gallium (Ga), and indium (In) from electronic waste (e-waste) is essential for resource sustainability and environmental protection. This research uses microwave-assisted treatment to investigate the carbothermal reduction of these four specific metals from their oxides in a simulated e-waste mixture, with carbon black serving as both a microwave coupling and reduction agent. Microwave processing is used specifically because it offers a rapid and energy-efficient alternative to conventional thermal methods, with the benefits of intrinsic heating and selective heating of materials. The first experiments centered on understanding the effects …

Predictive Modeling And Sustainability Assessment Of Hydrothermal Liquefaction Of Seaweeds: A Techno-Economic And Life Cycle Analysis Approach, Micheal O. Asama

Mechanical Engineering Theses

This study presents comprehensive predictive models and an economic and environmental assessment of HTL for converting macroalgae into biofuels and valuable co-products. Predictive models were developed based on experimental kinetic data to simulate batch HTL of brown seaweed, capturing the yields of biocrude, gas, biochar, and water-soluble compounds as functions of key process variables, including temperature, time, pressure, and water-to-biomass ratio. Analysis of Variance (ANOVA) confirmed that temperature and residence time significantly affect biocrude yield, with an optimal yield of 23% achieved at 283°C, 200 bar, 54 minutes, and a 10:1 water-to-biomass ratio. The model’s predictive accuracy was validated with …

Cfd Study On Two-Phase Flow Patterns In A Pipe With 90º Elbow In Different Operating Conditions, Hagar Alm-Eldin Bastawissi, Mohammed Ahmed Khafagy, E. A. El Shenawy Prof. Dr., Ahmed M. Salem Dr

Journal of Engineering Research

Recently, CFD has offered a technological solution for modelling multi-phase flow in which we can make endless simulations with reduced expenses and effort in high accuracy results; we shall also mention that experimental studies have limitations for safety considerations when experimenting with flow in high temperature or pressure values or medium nature as in nuclear or chemical flows.In this paper, we used the ANSYS FLUENT CFD program to simulate the two-phase flow in a pipe to study the effect of attaching a 90-degree elbow fitting to the piping system, seeking to find out the change in the pattern and resulting …

Process Simulation For Converting Co2 Emissions From The Cementindustry To Dimethyl Ether, Nour Abou Seada, Dina Aboelela

Biochemical Engineering

Climate change is the leading severe problem in the twenty-first century, which is associated with greenhouse gas emissions,carbon dioxide that is the foremost cause of global warming and super greenhouse effect. In this concern, to avoid hazardousproblems, the steady stream of CO2 effluents existing in the atmosphere must be transformed to beneficial products for beingused as an abundant chemical feedstock. Implementing a new green strategy, which is known for the catalytic hydrogenationof CO2 into alternative fuels and valuable chemicals, will be a long-lasting solution to alleviate CO2 emissions. In this paper,a process simulation showing the synthesis of dimethyl ether (DME) …

Hydrogen Production From Microbial Electrolysis Cells Powered With Microbial Fuel Cells, Dina Aboelela

Biochemical Engineering

No abstract provided.

Investigation Of Space Charge Effects On Co2 Electrocatalytic Reduction On Gd-Doped Ceria Via Scanning Kelvin Probe And Model-Based Bayesian Analysis, Alejandro Mejia

Graduate Theses, Dissertations, and Problem Reports (ETD)

In studying novel energy conversion and storage systems, such as high-temperature electrolysis, numerous underlying fundamental physical processes remain unclear or inadequately understood. Among these, the modeling and comprehension of surface reaction mechanisms, coupled with the intricate effects of space‑charge interfaces, remains an unclear and challenging area of research.

The work of this dissertation involves the development of a 2D finite element analysis model, leveraging the robust MOOSE framework from INL. This model, featuring inhomogeneous defect thermodynamics for near-surface chemistry, formulated through Poisson‑Cahn variational theory, has been exploited for studying the electrocatalytic reduction of CO₂ on gadolinia doped ceria. The …

Schaeffler Icvd Coating Machine, Louis Mcgrath

Williams Honors College, Honors Research Projects

Chemical Vapor Deposition (CVD) is mutual technology used to deposit thin film through a gaseous phase by vaporizing the solid materials. This conventional process usually requires high thermal stability of the materials, which is not applicable for most of the polymeric materials. Therefore, a novel process, initiated Chemical Vapor Deposition (iCVD) is developed by introducing the gaseous monument and initiator to form the thin film in-situ. By adjusting the free-radical polymerization in the vapor phase, a variety of thin and uniform polymer films can be achieved. Depending on the chemistry, iCVD has many categories. This report explains the design …

Isolation And Performance Test Of Green Low Dosage Hydrate Inhibitors From Local Materials For Improving Flow Assurance In Oil And Gas Industry, Makungu Madirisha

Tanzania Journal of Engineering and Technology (TJET)

The formation of gas hydrates in oil and gas industry can be minimized or prevented by the use of inhibitors. This paper reports on hemicellulose and modified lignin as low dosage gas hydrate inhibitors (LDGHIs). LDGHIs were isolated from sugarcane bagasse (SCB), plant gum exudates (PGE) of Acacia trees, and coconut coir, and further characterized by Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) spectrometer, porosimeter and thermogravimetric analyzer (TGA). The PGE and SCB yielded 77.75% and 12.38% of hemicellulose, respectively, while coconut coir yielded 35.59% of lignin which was modified to sodium lignosulfonate (SLS) to improve its solubility in …

Hydrothermal Liquefaction Of Saccharina Latissima For The Production Of Biofuel, Mayokun A. Oke

Mechanical Engineering Theses

We performed hydrothermal liquefaction of brown macroalga (Saccharina latissima) in the presence of homogenous and heterogenous catalysts such as KOH, Na₂CO₃, Pd/C, HZSM-5, Ce/HZSM-5, and Ni/SiO₂-Al₂O₃ in hot compressed water, to investigate their effects on product yield and composition in the biocrude. To investigate hydrocarbon production, we used methanol as co-solvent (methanol-to-water 1/4 vol.%) and as the only liquefaction solvent. We carried out the experiments in a batch reactor at 330^oC and 120-130 bar, and varying temperature, algae-to-water ratio, residence time, and pretreatment method. The biocrude yields …

Lead Acid Battery Recycling In The Current Tanzania Industrialization Drive: Challenges And Opportunities, Divina D. Kaombe

Tanzania Journal of Engineering and Technology (TJET)

ABSTRACT Advancements in automotive technologies, Information and Communications Technology and renewable energy technologies have increased the use of lead acid batteries as a source of portable and rechargeable energy. This has considerably increased the number of spent batteries with adverse effects on the environment and human health; which calls for recycling of spent batteries. This work was conducted to investigate challenges facing the formal business of recycling spent batteries and potential manufacturers of new lead-acid batteries in Tanzania. The work involved collection of information from key stakeholders such as collectors, dealers, Tanzania Revenue Authority and recyclers. It was found out …

Properties Of (Cd, Zn)S Films Deposited By Dc Co-Sputtering, Lwitiko P. Mwakyusa

Tanzania Journal of Engineering and Technology (TJET)

CdS thin film is commonly used as a buffer layer in most thin film solar cells. However, the buffer layer with less absorption in the visible region of the solar spectrum as well as that which provides perfect lattice matching with the absorbers is required. The incorporation of Zn in the CdS films can affect the structural and optical properties of the buffer layer. In this work, films of CdS and (Cd,Zn)S films were deposited by DC sputtering utilizing CdS and Zn targets. The concentration of Zn in the CdS was varied by changing the sputtering power of the Zn …

Synthesis, Characterisation And Catalytic Evaluation Of Castor Oil-Templated Mesoporous Sulfated Solid Acid Catalysts For Esterification Reaction, Steven Nyandoro Pr

Tanzania Journal of Engineering and Technology (TJET)

In bio-refinery and other catalytic reactions, heterogeneous catalysts confer advantage over homogenous catalysts due to minimized recovery and separation costs. However, templating surfactant and solid support for the synthesis of heterogeneous catalysts ought to consider their cheap sources and environmentally friendliness for their sustainable use. Thus, with the vision to make the process significantly benign, in the present work, solid acids were synthesised from renewable sources (castor oil as surfactant and rice husk as the source of silica). The synthesised castor oil-templated mesoporous sulfonic acid modified catalysts (SO3H-MTS and SO3H-MT-RHS) were characterised and evaluated for catalytic esterification of acetic acid …

Optimization Of Pulsed Laser Deposition Parameters For Single Crystalline (011) Oriented Tetragonal Pzt Thin Films, Mahamudu H. Mtebwa

Tanzania Journal of Engineering and Technology (TJET)

Recent advances in nanotechnology applications require the processing of high-quality thin films. A systematic study of the optimization of Pulsed deposition parameters for (110) oriented tetragonal PZT thin films is reported in this work. Prior to film deposition, a highly tetragonal Pb(Zr0.5, Ti0.95) or PZT 05/95 was selected to be deposited on (110) oriented Strontium titanate, SrTiO3 substrate, STO(110) to insure small compressive misfit strain. Unlike SRO, the LSOM bottom electrode was then successfully grown at 620 °C, 1.0 J/cm2 and a target-substrate distance of 3.9 cm. Finally, deposition parameters of PZT were progressively optimized through monitoring film morphological changes. …

Synthesis And Characterization Of Hybrid Catalysts For Fischer-Tropsch Jet Fuel Production, Jack M. Steinagel

Honors College Theses

Climate change is a major issue that our world is facing today. Finding renewable options for current infrastructure is paramount to solving this issue. Fischer-Tropsch synthesis of syngas from gasified biomass can produce renewable fuels that can be used in current conventional combustion engines. In order to make this process more industrially viable, a higher selectivity towards the desired range of liquid hydrocarbon products must be achieved. A novel way to do this is to introduce a catalyst to the Fischer-Tropsch reaction. The catalyst’s physical and chemical properties can promote chain growth of specific hydrocarbons. For the purpose of this …

Economic Feasibility Of A Methanol To Dimethyl Ether Production Process To Avoid Contract Failure Shortfalls From The Covid-19 Pandemic, Jacob Noll, Robert Wasson, Harrison Mckinnis

Honors Theses

Our team entered the 2021 AVEVA Academic Competition, where teams of undergraduate senior chemical engineering students competed across the country. The competition was composed of two parts: the base case design and the optimization of a chemical process. As part of the competition, our team is acting as the Engineering team for a fictional company that has given us this project. Due to COVID-19, our methanol producing company has lost a contract with a customer, leaving 23,000 tonnes/yr of unclaimed methanol. We have two choices with this methanol: either sell the methanol on the market at the spot price for …

Dry Reforming Of Methane Using Microwave Irradiated Metal Oxide/Coal Char Catalysts, Anthony Carter

Graduate Theses, Dissertations, and Problem Reports (ETD)

This research focuses on the synthesis of both shaped and amorphous powder materials, the combination of these materials with dried Powder River Basin (PRB) coal char, and their reactionary properties with methane and carbon dioxide gasses with conventional and microwave (MW) heating. The first goal of this project was to synthesize shaped micro and nano sized particles with ideal dielectric properties for converting electromagnetic energy into heat and proven capabilities of activating methane. These particles were synthesized via solvothermal, hydrothermal, and co-preceptory treatments alone and onto the surface of dried PRB coal char. PRB is a sub-bituminous, low-ranking coal (LRC) …

Thermal Control Development Of A Proton Exchange Membrane Fuel Cell System, Ola Mohammed Taha Al-Shalash

Mechanical Engineering Theses

A fuel cell is an electrochemical energy conversion device that uses fuel to generate electricity. It basically converts the chemical energy of reactants directly into electricity without combustion. In a Proton Exchange Membrane Fuel Cell (PEMFC), the reactants, hydrogen and oxygen, are fed into the two electrodes, anode and cathode, respectively. A reaction takes place at each electrode and produces electricity, as well as water, and heat as the by-products. In order to maximize performance of a fuel cell, many factors can be considered for tuning and control. Temperature management is one of these factors.

A thermal-fluid model of a …