Heat Transfer, Combustion Commons^™

Dynamics Of Separated Flows In Diffusers With Vortex Generators, Sandeep Eldho James

Mechanical and Aerospace Engineering Dissertations - Archive

Flow through curved diffusers is complicated due to the possibility of flow separation and secondary flows. Vortex generators (VGs) are a class of passive flow separation control devices used to improve the flow quality in curved diffusers by suppressing flow separation. However, the literature review demands an in-depth investigation on the physical mechanisms related to flow separation control. Thus, this study aims to improve the understanding of the underlying flow physics associated with VG-induced flow separation control in confined flows. The chosen geometry for this study is a well-documented asymmetric diffuser which exhibits a mild flow separation.

The theoretical formulation …

Machine Learning-Based Methodology For Multi-Objective And Multi-Design Variable Optimization Of Finned Heat Sinks And Evaluation Of Electrochemical Additive Manufactured Heat Sink Designs For Single-Phase Immersion Cooling, Joseph F. Herring Ii

Mechanical and Aerospace Engineering Dissertations - Archive

Traditional air-cooling along with corresponding heat sinks are beginning to reach performance limits, requiring lower air-supply temperatures and higher air-supply flowrates, in order to meet the rising thermal management requirements of high power-density electronics. A switch from air-cooling to single-phase immersion cooling provides significant thermal performance improvement and reliability benefits. When hardware which is designed for air cooling is implemented within a single-phase immersion cooling regime, optimization of the heat sinks provides additional thermal performance improvements. This work investigates performance of a machine learning (ML) approach to building a predictive model of the multi objective and multi-design variable optimization of …

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 …

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 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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …

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 …