Chemical Engineering Commons^™

Effectiveness Of Natural Coagulants In Purification Of Industrial Wastewater: A Case Of Cactus Pads And Watermelon Seeds, Neema O. Msuya

Tanzania Journal of Engineering and Technology (TJET)

This study assessed the potential of cactus pads and watermelon seeds as natural coagulants in industrial wastewater treatment. The global characterization of the two coagulants was done by using the Fourier Transform Infrared (FTIR) to determine the specific functional groups and by zeta potential measurements. A full factorial design was used to design the experiment and analyze the effect of three factors: coagulant dosage, settling time and particle size with three levels each and one replicate on the turbidity removal. ANOVA analyses were used to determine the significance of the factors. Results show that the amino and hydroxyl groups in …

Non-Catalytic Direct Partial Oxidation Of Methane To Methanol In A Wall-Coated Microreactor, Kelly Cohen

LSU Doctoral Dissertations

This project used an integrated mixer-reactor-heat exchanger microtube scalable module for the non-catalytic direct partial oxidation of methane in natural gas to methanol at elevated pressures (70-95 bar), reaction temperatures of 380-460C, reactant methane:air ratios of 0.5-4.4 and reaction zone residence times on the order of 1 min. Currently, methane in remote locations is often flared in large quantities rather than transported or converted to the more easily transportable methanol. However, if this gaseous methane were converted to liquid methanol at the wellhead, it could be transported in ways other than pipeline or used onsite.

Additionally, methane is currently converted …

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 …

Using Preformed Particle Gels To Control Transport In Geothermal Reservoirs: Mathematical Modeling, Philip Winterfeld, Baojun Bai, Yu Shu Wu

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

We are developing swellable Preformed Particle Gels (PPG), which can control preferential fluid and heat flow through fracture networks to increase the performance of EGS reservoirs. Part of this development is a mathematical model and numerical simulator to simulate PPG treatments by considering coupled thermal-hydraulic-mechanical effects, and gel swelling kinetics and plugging efficiency, from which an optimized gel treatment design and operation can be achieved. The starting point for our mathematical model is the TOUGH2-CSM formulation and code. The TOUGH2-CSM fluid and heat flow formulation is based on the TOUGH2 one for multiphase, multicomponent, and multi-porosity systems, with the latter …

Sustainable Aviation Fuel Production From Plastic Waste On Bifunctional Catalysts, Kamryn Culp

Williams Honors College, Honors Research Projects

Catalytic hydrocracking was studied as a chemical recycling method for converting mixed plastic polypropylene (PP) and polyvinyl chloride (PVC) waste into sustainable aviation fuel-range hydrocarbons. Addressing both plastic pollution and aviation-related CO₂ emissions, bifunctional Ni- and Pt-based catalysts supported on Al₂O₃ and TiO₂ were evaluated under 30 bar hydrogen pressure at 250 °C. The inclusion of PVC, often regarded as a catalyst poison due to chlorine content, was examined at 1 wt% and 5 wt% to assess catalyst tolerance to it and resulted performance. Reaction rates and product selectivity were analyzed using gas chromatography. Results show that Ni/TiO₂ outperformed other …

Examining Correlations Between Inhibition Efficiency And Compound Properties For Corrosion Inhibitors On Carbon Steel Rebar In Concrete, Nicole Langenfeld

Williams Honors College, Honors Research Projects

This project will look to determine if correlations exist between the inhibition efficiency and particular chemical properties of different corrosion inhibitors for carbon steel rebar in concrete affected with chlorides. Examining the inhibition efficiency of different corrosion inhibitors and attempting to find correlations or a general rule of thumb for what denotes a better corrosion inhibitor would be valuable. This similar concept has been seen with Lipinski's rule of 5 where he created a general guide to predict if compounds were orally active in humans. Since little information is readily available and no known correlations exist for corrosion inhibitors on …

Handling Emerging Sources Of Non-Determinism: Proportional Control With Quantum Noise, And Lyapunov-Based Economic Model Predictive Control To Address Stability, Profitability, And Dynamics Of Nonlinear Systems Under Cyberattack, Keshav Kasturi Rangan

Wayne State University Dissertations

The fundamental objective of process control is to establish safe process operating conditions while ensuring minimal economic loss. One of the fundamental challenges of achieving this objective is non-determinism from various sources that can create unexpected process behavior. A traditional goal in industrial process control is the rejection of disturbances, which are time-varying process inputs that are not directly modified by the control system. Other sources of uncertainty can include measurement inaccuracies/noise and changes in process dynamics as a plant operates. Many techniques have been developed to ensure notions of stabilization and safety despite these sources of stochasticity for both …

Transfection Of Ionizable Lipid Nanoparticles On Raw 264.7 And Mda-Mb-231, Lavanya Bhargava

Masters Theses

"This thesis investigates the preparation, characterization, and transfection efficiency of various ionizable lipid nanoparticles (LNPs) formulated for the delivery of mRNA encoding enhanced green fluorescent protein (EGFP) in RAW 264.7 macrophages and MDA-MB-231 breast cancer cell lines. The ionizable cationic lipid studied are ALC-035, C12-200, C14-4, PPZ-A10, DLin-MC3-DMA. The study addresses the need for effective gene delivery systems to provide a safe and versatile platform that protects and transports nucleic acids into target cells. LNPs were synthesized using microfluidic mixing methods, incorporating lipid components such as the cationic lipids, DSPE, DOPE, cholesterol and PEG lipids to achieve controlled particle sizes, …

Rhamnolipid As An Effective Srb Biocide – Determining A Solution To Replicate Anticipated Conditions, Elizabeth Zimmerer

Williams Honors College, Honors Research Projects

This project aimed to develop a laboratory-scale solution that replicates produced water conditions (CO₂ + brine) found in crude pipelines, with the added requirement of promoting the growth of sulfate-reducing bacteria (SRB). A previously successful study was used as a reference, which employed a hybrid salt solution containing essential nutrients and environmental factors. The proposed solution included 10 g sodium chloride, 1 g sodium pyruvate, 0.2 g ammonium chloride, and 0.8 g sodium sulfate per liter of deionized water. Electrochemical testing (Linear Polarization Resistance and Electrochemical Impedance Spectroscopy) was performed on solutions with and without rhamnolipid. Results from the …

The Antibiofilm Efficacy Of Copper And Zinc-Enhanced Borate Bioactive Glasses On Polymicrobial Biofilms, Sarah Fakher, David J. Westenberg

Biological Sciences Faculty Research & Creative Works

Healthcare-acquired infections (HAIs) are a significant global challenge driven by biofilm-forming pathogens. Polymicrobial biofilms, involving interactions between multiple microbial species, exacerbate treatment difficulties due to their enhanced resistance to antimicrobial therapies. Borate bioactive glasses (BBGs) are an emerging class of biomaterials that have attracted significant interest in infection control. The incorporation of copper and zinc into the BBG matrix can effectively disrupt biofilm formation and bacterial colonization. This study investigates the antibiofilm efficacy of copper and zinc-doped BBGs against polymicrobial biofilms formed by S. epidermidis, E. coli, and P. aeruginosa. Using static and dynamic biofilm models, BBGs were applied through …

Visual Understanding Of Rock Wettability Distribution To Contact Angle Regions And Oil Displacement Patterns In The Silty Sand Reservoir Via 2d Pore-Scale Modeling, H. Al-Ajaj, W. Al-Bazzaz, Ralph E. Flori, S. Alsayegh, H. Almubarak, D. S. Ibrahim, H. Al-Saedi

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

This study, conducted using a silty sand reservoir rock extracted from a Kuwait-producing oilfield, provides crucial insights into fluid distribution patterns and mineralogy, as well as wettability contact angle preferences. The method used for visual identification not only captures rock physics but also suggests effective oil recovery displacement strategies. Visual identification is presented using 2D image technology and a Scanning Electron Microscope (SEM). Analytical data are presented from electron bombardments and backscattering reflections collected in the BSE detector. These analyses were used to characterize the various surface boundary morphology parameters of the silty sand mineral surfaces, including area, perimeter, mineral …

Enhancing The Mechanical Properties Of Sla 3d-Printed Bio-Resin From Linseed Oil Using Cellulose And Lignin Biopolymers, Chukwunonso A. Ikedionu

College of Graduate Studies: Theses & Dissertations

Abstract

This research explores the development of bio resin from linseed oil by the process of epoxidation and acrylation to produce acrylated epoxidized linseed oil (AELO). Lignin and cellulose biopolymers were added as reinforcement at varying weight fractions of 1 wt.%, 2.5 wt.%, and 5 wt.%, and their mechanical performance was compared against pure AELO. The formulations were printed using an Elegoo SLA 3D printer to create standardized test specimens like tensile bars, compression cylinders, and hardness blocks, which were all prepared according to the ASTM testing standard.

The results indicate that reinforcement effects depend on both filler type and …

Identifying Potential Risk Areas Close To The Oil And Gas Pipelines Due To Subsidence In Qazvin Plain, Mahmoud Rajabi, Sanaz Vajedian, Ryan Smith, Neil Grigg, Hossein Nahavandchi, Mehdi Goli

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Surface displacement caused by natural and anthropogenic activities poses a significant risk to subsurface pipelines, particularly in areas experiencing subsidence. Stress and strain induced by deformation can lead to pipeline buckling and potential vulnerability. This study applies a multidisciplinary approach integrating interferometric synthetic aperture radar (InSAR) deformation analysis, well data, and geological context to assess the risk to oil and gas pipelines in Iran's Qazvin plain. The focus is on evaluating the impact of an unconfined aquifer, which has a lower risk of subsidence compared to a confined aquifer, on pipeline infrastructure. We analyzed multitemporal Sentinel-1 data collected between 2014 …

Development Of Self-Healing Polymer From Bio-Based Benzoxazine Blend With Poly(Ethylene Glycol) For Anti-Biofouling Applications, Pharaporn Yodkum

Chulalongkorn University Theses and Dissertations (Chula ETD)

Biofouling remains a significant challenge in marine industries, as conventional coatings often lose their antifouling efficacy once they become damaged. Incorporating self-healing capabilities into antifouling coatings has therefore emerged as a promising strategy to extend service life and maintain long-term performance. In this study, self-healing polymers were developed based on a bio-derived benzoxazine resin (E-fa), synthesized from renewable precursors including eugenol (a phenol source), furfurylamine (an amine source), and paraformaldehyde, and subsequently blended with poly(ethylene glycol) (PEG). The blends were formulated with varying weight ratios (95/5, 90/10, 85/15, and 80/20 wt/wt%) and PEG molecular weights (PEG-600, PEG-1500, and PEG-4000). This …

Synthesis And Assessment Of Biobased Acrylated Epoxidized Soybean Oil Resins For Stereolithography 3d Printing Of Microfluidic Devices, Natalie S. Romero Figueroa

College of Graduate Studies: Theses & Dissertations

This research focuses on the development and characterization of a biobased photocurable resin synthesized from soybean oil for use in stereolithography (SLA) 3D printing of microfluidic devices. The study explores a sustainable alternative to petroleum-based resins by performing an acrylation reaction on epoxidized soybean oil (ESO) to produce acrylated epoxidized soybean oil (AESO), which was then formulated into a photocurable resin with the addition of a photo initiator. The fabrication process involved designing microfluidic molds in SolidWorks and printing them using an Elegoo Mars 4 SLA printer under various exposure and layer thickness parameters. The printed samples consisted of microchannels …

Polymorphism And Mechanical Behavior In Hot-Pressed 3d-Printed Polyamide Composite: Effects Of Pressure And Temperature, John Barber, Patricia Revolinsky, Jimesh Bhagatji, Diego Pedrazzoli, Sergii Kravchenko, Oleksandr Kravchenko

Mechanical & Aerospace Engineering Faculty Publications

The aim of this work is to study the effect of high-temperature compaction (HTC) upon the polymorphism and the mechanical behavior of an additively manufactured (AM) carbon fiber-reinforced polyamide (PA6). Different pressure and temperature levels during HTC were tested to determine the overall effect on the mechanical behavior and material crystalline composition. Treated, carbon fiber-reinforced PA6 samples were analyzed using differential scanning calorimetry, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and three-point bending testing. When considered with respect to as-printed samples, an HTC temperature of 190 °C combined with 80 psi pressure resulted in an increased flexural modulus and strength …

Ground Testing Of A Magnetic-Electrostatic Separation System For Lunar Regolith Beneficiation, Peter Bachle, Charles Wood, Jeffrey Smith, Fateme Rezaei, David Bayless, William Schonberg, Daoru Han

Materials Science and Engineering Faculty Research & Creative Works

The separation of lunar regolith by mineral composition and size category is useful forin-situ resource utilization (ISRU). The research presented herein discusses the designing and development of equipment that has the potential to separate lunar regolith into aluminum, iron-titanium, and magnesium-iron ores. Along with the metal ore separation, this equipment shows the potential to separate regolith by size categories. The combined effect of these separation methods generates output that is valuable to subsequent use in metal and oxygen extraction, additive manufacturing, and regolith sintering processes. The designed equipment uses a dual-strength magnet system with N42 and N52 neodymium magnets for …

Investigation Of Dynamic Adsorption And Desorption Of Polymer Nanogel In Porous Media Through Microfluidics, Junchen Liu, Fuqiao Bai, Abdulaziz A. Almakimi, Mingzhen Wei, Xiaoming He, Ibnelwaleed A. Hussein, Baojun Bai

Mathematics and Statistics Faculty Research & Creative Works

Understanding the transport and retention of elastic nanogel and microgel particles in porous media has been a significant research subject for decades, essential to the application of enhanced oil recovery (EOR). However, a lack of dynamic adsorption and desorption studies, in which the kinetics in porous media are seldom investigated, hinders the design and application of polymer nanogel in underground porous media. In this work, we visualized and quantified the transport and dynamic adsorption of polymer nanogel in 3D glass micromodels that were manufactured by packing glass beads in capillaries. Calibrating the linearity of fluorescence intensity to concentration, we calculated …

Mechanistic Scale-Up Of Gas-Solid Fluidized Beds Via Local Hydrodynamic Similarity, Faraj M. Zaid, Thaar M. Aljuwaya, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

This study presents a detailed experimental evaluation of a newly developed mechanistic scale-up methodology for gas-solid fluidized beds. Traditional scale-up approaches typically rely on matching global dimensionless groups, which often fail to ensure local hydrodynamic similarity. In contrast, the new mechanistic method aims to achieve scale-up by matching the radial profiles of gas holdup between geometrically similar beds at corresponding dimensionless axial positions (z/D_c). This approach is based on the premise that when gas holdup profiles align, other key hydrodynamic parameters—such as solids holdup and particle velocity—also become similar. To validate this methodology, experiments were conducted in two …

A Comprehensive Review Of Piezoelectric Pvdf Polymer Fabrications And Characteristics, Nadia Ahbab, Sidra Naz, Tian-Bing Xu, Shihai Zhang

Mechanical & Aerospace Engineering Faculty Publications

Polyvinylidene fluoride (PVDF) polymer films, renowned for their exceptional piezoelectric, pyroelectric, and ferroelectric properties, offer a versatile platform for the development of cutting-edge micro-scale functional devices, enabling innovative applications ranging from energy harvesting and sensing to medical diagnostics and actuation. This paper presents an in-depth review of the material properties, fabrication methodologies, and characterization of PVDF films. Initially, a comprehensive description of the physical, mechanical, chemical, thermal, electrical, and electromechanical properties is provided. The unique combination of piezoelectric, pyroelectric, and ferroelectric properties, coupled with its excellent chemical resistance and mechanical strength, makes PVDF a highly valuable material for a wide …

Evaluation Of Physical And Chemical Stability In Liposomes Composed Of Mixed Phospholipids, Sharareh Rezaei, Kenny Mineart

Master’s Theses

Liposomes, spherical vesicles composed of lipid bilayers, are widely used in drug delivery due to their biocompatibility, biodegradability, and ability to interact with biological membranes. Despite these advantages, liposomes remain moderately unstable systems, highly susceptible to environmental stressors such as pH fluctuations, ionic strength variations, temperature changes, and interactions with other components. Addressing both chemical and physical instability is essential for translating liposomal formulations from experimental formulation to viable pharmaceutical products.

This study investigates the physicochemical characteristics of a mixed-phospholipid system in which one lipid is saturated, and the other is unsaturated (DMPC and DOPC respectively). Liposomes are prepared using …

Graphite Particles Modified By Zno Atomic Layer Deposition For Li-Ion Battery Anodes, Ahmad Helaley, Han Yu, Xinhua Liang

Chemical and Biochemical Engineering Faculty Research & Creative Works

Graphite, with a modest specific capacity of 372 mA h g−1, is a stable material for lithium-ion battery anodes. However, its capacity is inadequate to meet the growing power demands because the formation of an irregular solid electrolyte interphase (SEI) can result in unstable performance. In this research, we used a few cycles of atomic layer deposition (ALD) to deposit ZnO on graphite particles as an anode with improved electrochemical stability. Transmission electron microscopy revealed that ZnO was in the form of nanoparticles due to the inert surface properties of graphite and only a few cycles of ALD. Electrochemical characterization …

Thermo-Rheological And Tribological Properties Of Low- And High-Oleic Vegetable Oils As Sustainable Bio-Based Lubricants, Abiodun Saka, Tobechukwu K. Abor, Anthony C. Okafor, Monday U. Okoronkwo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Vegetable oil-based lubricants have attracted increased research attention in recent decades as sustainable alternatives to conventional petroleum-based lubricants in metal machining. However, more studies are required to fully elucidate the thermo-rheological and tribological properties. This study presents an investigation of the thermo-rheological and tribological properties of different vegetable oils, including low- and high-oleic soybean oil, high-oleic sunflower, safflower, and canola oils. The lubricity, and evolution of viscosity and thermodynamic properties as a function of temperature were investigated to obtain important parameters including the viscosity index, flow behavior index, flow activation energy, specific heat capacity, thermal conductivity, coefficient of friction, contact …

Effect Of Solvent On Nonanoic And Azelaic Acids Yield Enhancement From Oxidative Cleavage Of Oleic Acid, Chakreeya Santhadklang

Chulalongkorn University Theses and Dissertations (Chula ETD)

This study investigates the effect of solvent choice on the oxidative cleavage of oleic acid using hydrogen peroxide (H2O2) as the oxidant, with a focus on improving the yields of nonanoic acid (NA) and azelaic acid (AA). Solvent selection was found to play a critical role due to polarity differences between the reactants and oxidants. tert-Butanol was unsuitable because of its low boiling point, leading to the evaluation of higher-boiling solvents including guaiacol, acetoin, ethyl lactate, and isobutyric acid. Guaiacol and acetoin exhibited undesirable chemical reactivity, while ethyl lactate resulted in low yields due to hydrogen bonding with intermediate species. …

Experimental Investigation Of Surfactant Impact On Surfactant-Oil-Brine System For Surfactant Enhanced Oil Recovery, Chananpat Worpattanaluk

Chulalongkorn University Theses and Dissertations (Chula ETD)

Enhanced Oil Recovery (EOR) is a vital technique for improving hydrocarbon extraction efficiency from mature or low-production reservoirs. Among various EOR methods, chemical flooding, particularly surfactant-based EOR, has gained attention due to its ability to reduce interfacial tension (IFT), to alter rock wettability, and to mobilize trapped oil. However, the performance of surfactant systems is highly sensitive to reservoir salinity, temperature, and rock-fluid interactions, leading to surfactant precipitation, adsorption losses, and interfacial tension reduction. Therefore, understanding the effects of salinity, surfactant concentration, and the role of scale inhibitors on the physicochemical stability of surfactant-oil-brine systems is essential for designing robust …

Efficient Photocatalytic Hydrogen Evolution Via Novel Syntheses Of Srtio₃/G-C₃N₄ Heterojunction Photocatalysts, Chiramet Thatsanakunlaphan

Chulalongkorn University Theses and Dissertations (Chula ETD)

Strontium titanate/graphitic carbon nitride (SrTiO3/g-C3N4) heterojunctions are widely used as photocatalysts. However, traditional multistep synthesis methods for these photocatalysts often involve complexity, long processing times, and high energy consumption. To address these issues, a systematic comparison of various simplified synthesis approaches was conducted, emphasizing the influence of synthesis parameters on the structural properties and hydrogen evolution performance. Six comparative studies were conducted to illustrate the roles of solvent choice, thermal post-treatment, and synthesis route. Results showed that ethylene glycol consistently produced more active photocatalysts than ethanol in both one-pot and two-step solvothermal methods. Non-calcined samples exhibited superior hydrogen evolution activity …

Development Of Defective Tiox And Hfo2-X For Efficient Visible-Light-Driven Photocatalytic Degradation Of Organic Pollutants, Mohammad Rahim Pour

Chulalongkorn University Theses and Dissertations (Chula ETD)

The development of efficient photocatalysts capable of operating under visible light is critical for addressing persistent organic contaminants in wastewater. In this thesis, two complementary strategies are presented that exploit defect engineering and heterojunction construction to enhance charge separation, light absorption, and pollutant degradation. In the first study, titanium oxide quantum dots with a high density of oxygen vacancies were dispersed onto H-Beta zeolite supports via a sono-deposition approach. The zeolite substrate not only enabled uniform distribution of sub-5 nm TiOx particles, but also promoted pre-accumulation of cationic dyes, which significantly improved their subsequent oxidation. Structural and spectroscopic analyses confirmed …

Feasibility Study Of Utilization Of Calcium-Based Material For Integrated Methane Dry Reforming And Co2 Absorption-Mineralization Processes, Nattanan Watcharasawat

Chulalongkorn University Theses and Dissertations (Chula ETD)

This thesis investigates an integrated absorption-mineralization and dry reforming of methane (IAM-DRM) loop. The aim is to demonstrate the feasibility of using CaCO3 derived from amine scrubbing both as a CO2 sink and as reactive support for in situ Ni activation during DRM, while simultaneously regenerating the MEA solvent and calcium material for repeated use. CO2 absorption of monoethanolamine (MEA) yield equilibrium loadings of 0.66 mol CO2 mol-1 MEA with regenerated MEA maintaining identical performance. Mineralization on CaCl2 and Ca(OH)2 produced different phases product. Temperature programmed DRM demonstrated that mineralized CaCO3 can activate Ni in situ and sustain CH4 conversion. …

Electrochemical Reduction And Regeneration Of Carbamate, Nattiya Jumpadib

Chulalongkorn University Theses and Dissertations (Chula ETD)

A reliable method for removing carbon dioxide (CO2) gas from industrial emissions involves CO2 absorption into monoethanolamine (MEA) solution to achieve carbon neutrality. However, the regeneration of MEA is costly and still requires heat to release the CO2 that was captured and other processes to manage the CO2 onwards. Our research demonstrates that integrating CO2 capture with electrochemical CO2 conversion reduces regeneration processes and converts CO2 into valuable products. The electrochemical reduction and regeneration of MEA-CO2 adduct (carbamate) were investigated simultaneously by using copper pulse-electrodeposited on copper foils as a cathode in a microchannel reactor. The gas products were analyzed …

Effect Of Catalyst Bed Configuration On Temperature Profile And Reactor Performance For Fischer-Tropsch Synthesis : A Computational Fluid Dynamics Simulation, Natthasit Khawyen

Chulalongkorn University Theses and Dissertations (Chula ETD)

This research investigates the performance of the Fischer–Tropsch reaction in a fixed-bed reactor packed with spiral-structured catalysts using COMSOL Multiphysics to evaluate heat management, hot spot reduction, and the enhancement of high-value product selectivity. The study comprises two main scenarios. The first examines the effects of tube spacing and number of tubes in a multitube reactor arranged in a hexagonal pattern using a 20% Co/SiO₂ spiral-structured catalyst. In models R1–R4, which contain a fixed number of 10 tubes, tube spacing was found to have only a limited influence on temperature distribution; all models still exhibited a hot spot near the …