Mechanical Engineering Commons^™

Design And Analysis Of Electrochemical Additive Manufacturing Based Cold Plates And Heat Sinks For Enhanced Electronics Cooling And Temperature-Dependent Density Characterization Of Phase Change Materials, Jacob Lamotte-Dawaghreh

Mechanical and Aerospace Engineering Dissertations - Archive

The body of work that comprises this dissertation is divided into two main sections. The first section is regarding novel heat sink and cold plate designs that leverage a metal additive manufacturing process called electrochemical additive manufacturing (ECAM) to drive increased thermal performance. The continuous advancements in electronics computational capabilities have resulted in ever-increasing thermal loads at the component and data center server level. These strides within the field are soon to be compounded by the rise of artificial intelligence and machine learning technologies. Traditionally, high performance electronics components have been able to be cooled by forced-air cooling; however, the …

Carbon Dioxide Gasification Of Biochar: A Study On Utilizing Captured Co2 To Mitigate Greenhouse Gas Emission And Improving Carbon Conversion Efficiency, Nnamdi Ofuani

College of Graduate Studies: Theses & Dissertations

With rapidly growing global economies and world population, fossil fuel continues to play a major role in meeting current energy demands. Carbon capture and storage (CCS) technologies have, hence, been implemented to reduce CO₂ emissions in the atmosphere. With the implementation of CCS technologies comes the need to utilize the captured CO₂. This research, therefore, proposes CO₂ gasification of biochar as a viable carbon utilization pathway. With captured CO₂ coming at various concentrations, there is a need to understand how CO₂ concentration affects biochar conversion to useful products. This study, therefore, evaluates the effects …

Analysis Of Factors Affecting Engine Knock In Modern Spark Ignition Gasoline Engines To Improve Engine Efficiency, Siddharth Gopujkar

Dissertations, Master's Theses and Master's Reports

Spark ignition engine knock is an issue that has persisted for over a century. Knock prevents the spark in an SI engine to be deployed at the most optimum time in the engine cycle, which leads to a decrease in the efficiency of the engine. A reduction in the efficiency directly translates to increased emissions and fuel costs. This research looks at experimental works to analyze the impact of three separate factors on knock in an effort to minimize it and improve engine efficiency.

The first factor is fuel chemistry – how Research Octane Number (RON) and Motor Octane Number …

A Novel Computational Analysis Of Boundary-Driven Two-Dimensional Heat Flow With Internal Heat Generation, Muhammad Abid, Madiha Bibi, Nasir Yasin, Muhammad Shahid

Mathematics & Statistics Faculty Publications

Accurate numerical solution of parabolic and elliptic partial differential equations governing two-dimensional heat transfer is critical for engineering simulations but computationally challenging. This work employs key numerical techniques finite differences, conjugate gradients, and Crank-Nicolson time stepping to solve the heat diffusion equation and analyze method performance. The Poisson equation is discretized using second-order central finite differences and solved with the conjugate gradient approach to determine the steady state solution. The transient heat equation is integrated in time via the Crank-Nicolson implicit scheme, also utilizing conjugate gradients. The methods effectively compute solutions matching analytical and boundary conditions. Convergence and stability are …

Numerical Simulation And Optimization Of Fin Configurations For Enhanced Heat Sink Performance In Aluminum And Copper Materials, Rimpy Singh

Mechanical and Aerospace Engineering Theses - Archive

The constant evolution of data centers and high-power electronic systems has raised critical challenges in heat dissipation and thermal management. Single-phase immersion cooling, where electronic components are submerged in a thermally conductive but non-electrically conductive liquid (dielectric liquid), offers improved heat dissipation capabilities and emerges as a promising alternative to traditional air-cooling methods, which often fail to meet the thermal demands of densely packed, high-power systems. This study investigates and compares the thermal performance of aluminum and copper heat sinks with fin thicknesses of 0.33 mm and 0.54 mm, respectively, using finite element analysis based on computational fluid dynamics (CFD) …

Advanced Thermal Management Solutions For High-Powered Chips: A Comprehensive Study On Immersion Cooling And Electrochemical Additive Manufacturing-Based Cold Plates, Gautam Gupta

Mechanical and Aerospace Engineering Dissertations - Archive

This dissertation investigates advanced thermal management strategies for high-performance computing systems to address the escalating thermal challenges posed by increasing power densities and computational demands. Chapter 1 evaluates the efficacy of forced convection Single-Phase Immersion Cooling (SPIC) with a dielectric fluid (EC-110) compared to traditional air cooling for a 776 W server. Computational Fluid Dynamics (CFD) simulations demonstrate significant reductions in chip junction temperatures, maximum Dual In-line Memory Module (DIMM) temperatures, and server pressure drop with immersion cooling, highlighting its superior heat dissipation capabilities.

Chapter 2 delves into the comparative analysis of forced and natural convection Single-Phase Immersion Cooling techniques. …

High-Fidelity Coupling For Studies Of Ablative Materials At Hypersonic Conditions, Aleksander Zibitsker

Theses and Dissertations--Mechanical and Aerospace Engineering

The development of accurate models and robust numerical tools for simulating ablative thermal protection materials (TPMs) in hypersonic flows is crucial for advancing atmospheric entry and hypersonic technologies. Traditional methods for simulating ablative materials often rely on heavy assumptions, such as equal heat and mass transfer coefficients and chemical equilibrium in the boundary layer, leading to conservative thermal protection system (TPS) designs and insufficient accuracy for certain in-flight ablation phenomena.

This work presents a high-fidelity and versatile coupled framework between hypersonic flow and material response solvers. The flow domain is modeled with an innovative overset CHAMPS NBS-Cart solver, which features …

Identifying Savings In Residential Electricity Consumption Through Data-Driven Analysis, Scott J. Maurer

Dartmouth College Master’s Theses

Climate change and rising electricity demand have driven the need for energy efficiency in buildings. Single-family residential buildings present opportunities for improvement, but current strategies for identifying savings are labor and capital-intensive. Developing a residential version of a virtual energy audit tool offers a cheaper, non-intrusive alternative. This study used 25 all-electric homes in Florida to refine algorithms from the previously developed EDIFES code, originally designed for commercial buildings. The analysis utilized one year of 15-minute electricity consumption, area, stories, and location. These markers include heating and cooling type, setpoint set back, HVAC load, pool pump load, refrigeration load, and …

Design Of An Experimental Solid Rocket Motor, Johnathan Bettes, Andrew Fuller

Williams Honors College, Honors Research Projects

This project utilizes mechanical and chemical principles to characterize propellant grains and to manufacture a custom nozzle to create experimental Solid Rocket Motors (SRMs) with a propellant called Angry Listerine. For the propellant grains, one major non-chemical factor that determines its thrust performance is the grain geometry, or the core of the grains for which hot gases flow through the propellant and out of the nozzle to further react with exposed chemical surfaces. The two kinds of grain geometries analyzed and tested in this report are called MoonBurner, an offset circular core, and Finocyl, a gear-shaped core. The nozzle for …

Propulsion Heat Analysis Nuclear Trajectory Optimization (Phantom), Ana Clecia Alves Almeida, Jonathan Davis, Ryan Dippolito

Williams Honors College, Honors Research Projects

Interplanetary Travel requirements necessitate the use of increasingly complex propulsion systems. Nuclear Thermal Propulsion (NTP) is a cutting-edge concept that holds immense potential for the future of space exploration. By utilizing nuclear fission to heat a propellant and generate thrust, NTP offers the potential for unprecedented efficiency, enabling faster interplanetary travel and extended mission capabilities. A nuclear thermal rocket engine is a type of propulsion system that utilizes the heat generated by a nuclear reactor to heat and expel a propellant, typically hydrogen, at high velocities to produce thrust. The engine consists of three main subsystems: the nuclear reactor, the …

Investigation Of Operational Parameter Differences Between The Standard Ron Test Method And Knock-Limited Modern Spark-Ignition Engine Operation, Alexander Hoth

Dissertations, Master's Theses and Master's Reports

Octane numbers (ONs) are used worldwide to rate the knock propensity of gasoline-like fuels for spark-ignition engines, making ONs the leading indicator of fuel quality for commercial distribution. The ONs were established 90 years ago and have only received minor changes compared to significant advancements in modern engine operation and fuel composition. This has resulted in discrepancies between knock-limited modern engine operation and standard ON ratings. This dissertation used a standard CFR octane rating engine at Argonne National Laboratory that was instrumented with modern combustion research tools to investigate key differences between the Research Octane Number (RON) rating conditions and …

Stable Energy-Efficient Macro-Scale Partial Flow-Boiling Operations Using Microstructured Surfaces And Ultrasonics, Divya Kamlesh Pandya

Dissertations, Master's Theses and Master's Reports

Controlled but explosive growth in vaporization rates is made feasible by ultrasonic acoustothermal heating of the microlayers associated with micro-scale nucleating bubbles within the microstructured boiling surface/region of a millimeter-scale single-channel heat exchanger (HX) – part of a typically multi-channel heat-sink. The experiments illustrate the achievement of a remarkably high stable heat flux (10 – 80 W/cm²) for a partial flow-boiling-based cooling approach and exceptional efficiency through active/passive enhancement in the vaporization rates into the heterogeneously nucleated micro-bubbles (through acoustothermal heating of their microlayers) and their removal rates (typically within the passive microstructured region of boiling). A controlled …

Analysis Of Variations In Flow-Independent Liquid Jet-In-Crossflow Injections, Michael Scott

Honors Undergraduate Theses

Liquid fuel injection is a critical mechanism for the deliverance of liquid fuel in contemporary aircraft propulsion combustion systems due to its outsized influence in providing optimal combustion conditions and improving overall aircraft efficiency and performance. Despite this, these liquid jet in crossflow (LJIC) systems are highly variable due to conditions in the jet and the surrounding airflow, leading to variability in performance behavior and inconsistency in fuel mixing and combustion efficiency. This has prompted the introduction of solid pintile obstructions of novel designs to provide a more flow-independent fuel injection scheme and decrease variability of the jet properties against …

Mathematical Modeling Of Coupled Heat And Mass Transfer In Metal-Hydride Hydrogen Storage Systems, Muhammad Hasnain

College of Graduate Studies: Theses & Dissertations

As a promising clean energy carrier hydrogen has recently gained significant interest, but its efficient and safe storage is a major challenge. Compared to the gaseous state and liquid state, metal hydrides (MH) offer a potentially more effective storage approach for hydrogen. However, the main challenge in this approach is the low thermal conductivity of the MH bed that leads to low heat transfer and ultimately to higher charging and discharging times. The purpose of this work is to develop an in-house comprehensive heat and mass transfer model for hydrogen sorption in MH reactors to simulate the dynamic behavior of …

Investigations Of Performance And Emissions Of A Fischer-Tropsch Gtl Sustainable Aerospace Fuel With Lubricity Improver In A Compression Ignition Engine With Butanol Port Fuel Injection, James B. Willis

College of Graduate Studies: Theses & Dissertations

As there is increasing concern over emissions of traditional fossil fuels, as well as the future of continued reliance on this dwindling resource, it is becoming increasingly evident that alternative fuels are a necessity. This research investigates the use of a Fischer-Tropsch fuel from natural gas feedstocks, S8, in an internal combustion research engine with a common rail fuel injection system. This synthetic kerosene fuel has a high DCN of 62, indicating high affinity to autoignition compared to conventional pump diesel (ULSD) at 48 DCN. However, due to the process by which it is produced, this fuel lacks the necessary …

Numerical Modeling Of Thermal Runaway In Lithium-Ion Batteries Using Decomposition Kinetics And Inter-Cell Contact Resistance, Shehzad Khan

College of Graduate Studies: Theses & Dissertations

Lithium-ion batteries (LIBs) are central in numerous high-demand applications due to their high energy density and prolonged cycle life. Despite these advantages, their susceptibility to thermal runaway (TR) poses a significant safety risk, with the potential for catastrophic failures. This study focuses on the thermal behavior of prismatic lithium-ion cells, using a finite volume-based partial differential equation (PDE) solver developed in MATLAB and JULIA to model TR behavior. This solver accurately simulates transient behaviors, convection, diffusion, and source terms across various coordinate systems. By engaging in a series of increasing complex case studies, this research aims to identify the critical …

Co-Firing Of Lpg And Diesel Fuels Through An Innovative Double Swirl Burner: Combustion Characteristics And Exhaust Emissions, Eslam O. Mater, Karim M. Soliman, A. Abdulnaim, Ahmed Abdelrazik Emara, Ahmed Salah Elsahy, Hany A. Moneib

Trends in advanced sciences and technology

The current stringent environmental regulations, the depletion of fossil fuels and the emergence of oil biofuels and synthetic gases had motivated combustion scientists to search for alternative technologies that meet efficient burning, flexible use of multiple fuels and conform to a clean environment. In that respect, several developments had emerged including, low swirl combustion for partially premixed mixtures, “Mild” combustion for diffusion flames. The present experimental study introduces a new concept that combines separate admissions of fuel and air with a central recirculation zone following the diffusion combustion mode, partial premixing within a premix chamber resulting in the creation of …

Air Jet Assisted Combustion Of Oil Diffusion Flames: Effects Of Injection Location And Excess Air Factor, Moustafa Ahmed Gamaleldin, Neama Youssef Ramadan, Ahmed Mohamed Abdulnaim, Ahmed Abdelnasser Adam, Ahmed Abdulrazik Emara, Hany Ahmed Moneib

Trends in advanced sciences and technology

This study investigates a novel methodology for a coaxial disc stabilized burner with a central jet oil spray. It introduces multiple air injection jets within the burner gun's exit section, promoting earlier fuel vaporization and rapid fuel-air mixture formation in the premixing zone. This directly contributes to improved overall combustion efficiency and reduced exhaust emissions. The focus lies on identifying the optimal location for the air injection jets (fixed load, constant jet momentum, and angle) within the exiting premixing zone of the burner gun. In-flame measurements are conducted inside a cylindrical combustor at different air injection locations and varying excess …

High-Pressure Ignition And Flame Propagation – An Experimental And Numerical Study, James Shaffer

Graduate Theses, Dissertations, and Problem Reports (ETD)

The next generation of advanced combustion devices is being developed to operate under ultra-high-pressure conditions, to improve combustion efficiency and reduce pollutant emissions. However, at such extreme conditions, flame tends to become unstable, and measurement of fundamental properties becomes challenging. The laminar burning speed ( ) is among those properties, as it is required for the validation of kinetic models and the modeling of turbulent combustion. One potential method to resolve this issue and achieve measurement at very high pressures (i.e., 20-50 atm), is focusing on ignition affected region. The flame kernel in this region is more resistant to perturbations …

Natural Convection Heat Transfer Characteristics Of Sierpinski Carpet Fractal Fins In Horizontal And Vertical Orientations, Ayomide Ayoola

College of Graduate Studies: Theses & Dissertations

This study investigates the thermal performance of fins with perforations inspired by the Sierpinski carpet fractal pattern under natural convection conditions in both vertical and horizontal orientations. The objective is to analyze the effects of fractal iteration levels on three primary performance metrics: efficiency, effectiveness, and effectiveness per unit mass. Experimental evaluations were conducted for fractal fins from iterations 0 through 4, utilizing aluminum material, with each fin heated to controlled conditions. The results reveal that efficiency generally decreases with higher fractal iterations, reflecting increased thermal resistance associated with greater porosity and complex geometry. However, effectiveness per unit mass improves …

Fluid Flow And Thermal Performance Investigation Of Twisted Elliptical Tubes For Use In High Prandtl Number Systems, Connor F. Donlan

Theses and Dissertations

The development of clean energy systems is paramount to reducing mankind's climate impact. These clean energy systems include solar, wind, and nuclear power where nuclear power shows a reduced lifetime carbon dioxide footprint per kilowatt hour compared to other sources [102]. Advanced nuclear reactors, fusion energy systems, and concentrated solar power designers are looking at using molten salt heat transfer fluids and improved heat exchanger design to increase power production and efficiency of clean energy systems. The improving heat transfer within the main heat transfer components within advanced nuclear reactors will enable increased efficiencies and power production.

Heat transfer improvements …

A Project-Based Learning Activity For An Engineering Technology Heat Transfer Course To Design A Shell-And-Tube Heat Exchanger, Nathan Luetke, Orlando Ayala

Engineering Technology Faculty Publications

Thermofluids courses demand a strong grasp of mathematics and employ physics extensively to describe physical systems. Heat transfer, in particular, presents challenging topics, which can be even more daunting for engineering technology students. In this paper, we present the implementation of a project-based learning activity in the engineering technology heat transfer course. The students' task involves designing a shell-and-tube heat exchanger to meet specific minimum requirements. The objective is to provide students with a real-world assignment that enhances their heat transfer calculation skills. To accommodate instructors' busy schedules, we have developed an assignment that is user friendly. Detailed instructor guides …

Experimental Investigation And Performance Analysis Of The Transformational Challenge Reactor (Tcr) System Under Various Temperature And Pressure Conditions, Ahmed Mohamed Ali Soliman

Dissertations and Theses

The Transformational Challenge Reactor (TCR) represents a significant advancement in nuclear reactor technology, taking into consideration modularity, efficiency, and safety. This study explores the coupling between thermal behavior and the coolant gas flow behavior of the TCR’s 3D-printed ceramic core under various operating conditions. Using nitrogen as a coolant, experiments were performed at pressures ranging from 20.4 bar to 40.8 bar (300 to 600 psi) and temperatures from 100°C to 300°C. The main parameters including gas inlet and outlet temperatures, the TCR wall temperature at the inlet and outlet, and flow rates, were analyzed to evaluate heat transfer efficiency and …

Depressurization Characteristics Of Steam-Based Reciprocating Vacuum Pump, Hongling Deng

Dissertations

This dissertation introduces a novel vacuum technology that leverages low-pressure saturated steam and cooling-controlled condensation, offering an efficient way to utilize low-grade thermal energy sources like waste heat, steam, or solar energy. At the heart of this technology is a unique duo-chamber vacuum pump system, featuring a reciprocating piston and a heat-conductive wall, designed to generate a vacuum through steam-condensation and cooling processes.

The core of this research lies in developing and validating mechanistic models for the steam-condensation depressurization process, a complex phenomenon involving phase change and transport mechanisms. Prior to this work, these mechanisms were not sufficiently modeled or …

Heat Transfer Enhancement In Nanofluid Flows Augmented By Magnetic Flux, Kozhikkatil Sunil Arjun, Rakesh Kumar

Makara Journal of Technology

Heat transfer enhancement could be realized using magnetohydrodynamics together with nanofluids specifically in flow micro-convection in a microtube, flow past a vertical porous plate, and square duct flow with discrete heat sources numerically. A critical value for the Rayleigh number, a maximum value for the magnetic field strength, a low Reynolds number, and volume concentrations exists for thermal enhancement to simulate nanofluid flow in a microtube. Heat transfer enhancement is observed with a reduction in the magnetic field strength in a flow past a heated porous vertical plate. Alumina nanofluid subjected to Hartmann number 10 can boost 81% enhancement in …

An Image Processing Technique For Studying The Flame Structure Using Single Shots Of Oh-Plif Diagnostics, Hazem M. Al-Bulqini, El-Shafie B. Zeidan, Farouk M. Okasha, Mohy S. Mansour

Mansoura Engineering Journal

Laser diagnostic techniques have played a crucial role in enhancing our understanding of combustion processes. Among these techniques, Planar Laser-Induced Fluorescence (PLIF) utilizing OH radicals has proven to be a powerful tool for investigating reaction zones, flame curvature, and flame surface density in diverse flame modes including premixed, non-premixed, and partially premixed flames. However, to fully harness the potential of experimental measurements and laser diagnostics in studying combustion processes, a comprehensive grasp of image processing techniques and tools is essential for effectively analyzing captured images and extracting valuable information. In this study, we present a detailed algorithm that facilitates the …

Capabilities Of Sintered Silver As A High Temperature Packaging Material, Bakhtiyar Mohammad Nafis

Graduate Theses and Dissertations

With electrification progressing across many sectors including industry, automotive and aerospace, the power density requirements are changing. The increased power density results in higher and higher ambient temperatures that electronics are exposed to. The response has been to move towards wide bandgap (WBG) semiconductor devices that can withstand much greater temperatures and can operate at much higher voltages than silicon. Additionally, these WBG devices deliver low drain-source on resistance (RDS_on) capabilities, enabling high current power modules that increase power density even further. This also requires the packaging to evolve in order to withstand the new requirements. As a result, researchers …

Thermal Resistance Characterization Of High-Voltage Sic Power Module, Landon Lemmons

Mechanical Engineering Undergraduate Honors Theses

Researchers within the University of Arkansas Electrical Engineering Research Department have embarked on a project aimed at enhancing the thermal performance of high-voltage power modules. To aid in the progress of this project, the design, and development of a thermal tester device are needed. The primary objective of this device is to determine the various thermal properties of high-voltage power modules that the electrical engineering department has developed. Additionally, the project aims to facilitate electrical loading tests on power modules and provide researchers with the means to calibrate the power module in terms of thermal load. This project also possesses …

Experimental Study On The Impact Of Low Thermal Inertia Thermal Barrier Coatings On Ppci-Diffusion Gci Combustion, Kunal Vedpathak

All Theses

The application of thermal barrier coatings (TBCs) has been studied in homogenous charge compression ignition (HCCI), conventional diesel combustion (CDC), and spark ignition (SI). Gasoline compression ignition (GCI) combines the low soot and NOx emissions of HCCI with combustion controllability through fuel stratification. GCI has become an interesting prospect due to the reduction in gasoline consumption due to the electrification and hybridization of the light-duty sector. It can be used as a preferred combustion mode in heavy-duty engines to reduce emissions with minimal modifications. GCI exhibits better combustion efficiency than HCCI. Advances in material technology have combined low thermal conductivity …

Advanced Jet Impingement Cooling For Power Electronics, Reece Whitt

Graduate Theses and Dissertations

Convective heat transfer by jet impingement cooling offers a suitable solution for high heat flux applications. Compared to techniques that rely on bulk conduction in series with convection, direct liquid impingement reduces the thermal resistance between power device hot spots and the coolant. Using additive manufacturing processes, location specific jets can be integrated into high voltage power electronics systems. Custom manifolds can be designed to reduce pressure drop, while simultaneously fine-tuning the thermal management efficiency. Although capable of highly efficient cooling, static impingement devices must be designed for the worst-case cooling requirements for a transient power profile, possibly resulting in …