Heat Transfer, Combustion Commons^™

Thermal Heterogeneity And Lithium Plating During Fast Charging Of Lithium-Ion Battery., Ayodeji Avis Adeniran

Electronic Theses and Dissertations

Presently, widespread adoption of electric vehicles (EVs) is hindered by challenges associated with XFC, including heat generation, lithium plating, and accelerated battery degradation. This dissertation addresses these barriers through two coordinated themes—lithium plating and thermal management—spanning four manuscripts that integrate operando diagnostics, physics-based simulation, and module-level design optimization. The first theme seeks a fundamental investigation into the dynamic interplay between temperature heterogeneity and lithium plating during fast charging, a phenomenon that poses significant limitations on the performance of graphite-based anodes. Firstly, a custom operando cell with a sapphire window was designed to enable synchronized MWIR thermography and optical imaging of …

Finite Element Analysis Of Thermal-Mechanical Instabilities In Nonmetallic Friction Composite Material, Joseph-Shaahu Shaahu

Electronic Theses and Dissertations

Thermal-mechanical instability (TMI) has been a research topic of interest as it focuses a lot on transportation systems. Thermal-mechanical instability was first noticed in railway and experimentally studied with a pin-to-pin or pin-to-surface setup of sliding contact. The topic has been extended into brakes and clutches which are two of the most common sliding systems most susceptible to thermal buckling and thermoelastic instability (TEI), where thermal buckling and thermoelastic instability are two sub-categories of thermal-mechanical instability. Thermal-mechanical instability is an ongoing research to better understand the phenomenon and the limits at which such instability occurs. This work delved into the …

Measurement Of Conduction, Radiation, And Convection Thermal Energy To Assess Baking Performance In Residential Ovens., Sean Simpson

Electronic Theses and Dissertations

Residential ovens are complicated thermal environments capable of delivering convection, conduction, and radiation heat transfer to food. The amount and mode of heat transfer can change based on the design of the oven cavity, cooling systems, and oven cycle algorithms. Studies have shown that the changes in one heat transfer mode can have an impact on the quality of baked goods. The many variables involved make designing residential ovens a time consuming and costly process. The goal of this study is to adapt thermal energy sensing technology to collect energy data from a residential oven and develop correlations to quality …

Experimental Evaluation Of Heat Leak From Anti-Sweat Components Into Fresh Food And Freezer Compartments Of A Household Refrigerator., Delva Felissaint

Electronic Theses and Dissertations

Condensation beads forming on outside surfaces around a refrigerator is an undesirable byproduct driven by the cold temperature exhibited throughout the unit. To combat this issue, anti-sweat components usually in the form of electrical heaters or tubes carrying hot refrigerant, bring heat to the cold surfaces to ensure their temperatures do not drop below the dew point. Some heat produced by the anti-sweat components may transfer to the interior refrigerated compartment. The purpose of this study is to quantify how much heat from the anti-sweat components are entering the fresh food and freezer compartments and what impact that has on …

Development And Applications Of A Sensor For Measurement Of Different Modes Of Heat Transfer On Foods In A Residential Oven., Kervins Petit-Bois

Electronic Theses and Dissertations

Thermal characterization of an oven is an important part of designing an oven. Understanding how changes in cooking algorithm, oven construction, and oven materials affect cooking performance is critical in ensuring that an oven is properly designed. Often temperature data is used to characterize oven behavior, but this neglects the mode of heat transfer used to achieve these temperatures. Several studies have compared the different modes of heat transfer and cooking performance and have shown that cooking performance in radiation dominated modes are different than in convection dominated modes. The goal of this study is to develop a heat flux …

Nucleate Boiling Under Different Gravity Values: Numerical Simulations & Data-Driven Techniques., Sandipan Banerjee

Electronic Theses and Dissertations

Nucleate boiling is important in nuclear applications and cooling applications under earth gravity conditions. Under reduced gravity or microgravity environment, it is significant too, especially in space exploration applications. Although multiple studies have been performed on nucleate boiling, the effect of gravity on nucleate boiling is not well understood. This dissertation primarily deals with numerical simulations of nucleate boiling using an adaptive Moment-of-Fluid (MoF) method for a single vapor bubble (water vapor or Perfluoro-n-hexane) in saturated liquid for different gravity levels. Results concerning the growth rate of the bubble, specifically the departure diameter and departure time have been provided. The …

Fluid Structure Interactions Within A Common Rail Diesel Injector., Russell Prater

Electronic Theses and Dissertations

The internal flow of a high-pressure diesel injector is simulated numerically to investigate the complex transient flow structures and the unsteady forces imparted to the injector needle that result from the asymmetric flow fields developed during operation. The gas-liquid two phase flow is simulated using a mixture model with the cavitation numerically modeled using the Zwart-Gerber-Belamri model. Both the k-ε model and the detached eddy simulation (DES) model are used, and the numerical results are compared. This dissertation looks at the internal flow of a generic injector at different lifts and characterizes the flow parameters at high lift and low …

Monitoring Of State Transitions In Extreme Environment Application Materials Using Fiber Bragg Grating Sensors, Sabuj Khadka

Electronic Theses and Dissertations

By embedding both a single fiber Bragg grating (FBG) sensor and a thermocouple (TC) during the manufacturing for extreme environment applications of certain classes of materials such as metals and polymers, a novel in-situ approach was developed to precisely monitor their entire manufacturing processes. This novel monitoring technique was able to identify many characteristic points during the curing of room and high-temperature epoxies and the solidification processes of metal alloys composed of tin and bismuth which were selected in this research purely for verification purposes. Some of the characteristic points identified for the epoxies were: (i) the gel point, (ii) …

Experimental Evaluation Of Heat Leak And Convective Heat Transfer In A Household Freezer., Catherine E. Berghuis

Electronic Theses and Dissertations

Heat leak into household refrigerated cabinets is a key driver affecting energy consumption and efficiency of the cooling system. Additionally, knowledge of heat transfer coefficients of internal surfaces is valuable in the development of cabinet and system level performance simulations. Several studies have examined heat leak of refrigeration units using heat flux sensors (HFS); however, no such studies have used heat flux measurements to derive convective heat transfer coefficients of the refrigerated unit walls. The goal of this study is to evaluate the use of HFS to quantify heat leak into a 490-liter freezer and determine the wall convective heat …

Experimental Investigation Of The Manufacture Of Tunable Graphene Oxide Filter Membranes Using Intense Pulse Light, Joshua H Kotter

Electronic Theses and Dissertations

Reduced graphene oxide is a thin, strong, and inexpensive material with a channel and pore structure that make it a promising candidate for a filtration material. Reduced graphene oxide has been produced and tested in the laboratory, but a lack of scalable manufacturing techniques have limited its commercial use.

This thesis has shown that graphene oxide can be rapidly manufactured with an industrially scalable flash reduction process. The flash reduction process uses 0.58 millisecond pulses from a xenon lamp to reduce the graphene oxide film in less than a minute. Results for partially reduced graphene oxide membranes tuned by the …

The Effects Of 3d Printing Parameters And Surface Treatments On Convective Heat Transfer Performance, Lucas N. Pereira

Electronic Theses and Dissertations

Additive manufacturing technology and applications have quickly expanded in many industries over the last five years. As additive manufacturing is studied and refined, improvements in resolution and strength have helped propel further growth of the industry. This study focuses on an additive manufacturing technology called fused filament fabrication (FFF). FFF involves the extrusion and layer-by-layer deposition of a molten thermoplastic material to create the desired part. One potential new application of fused filament fabrication is the manufacture of heat exchangers and heat sinks. This study focuses on developing baseline experimental data related to convective heat transfer coefficients over surfaces of …

Fundamental Characteristics Of Supercritical Co2 Combustion, Raghu Veera Manikantachari Kancherla

Electronic Theses and Dissertations

The direct-fired supercritical CO2 (sCO2) cycle is conceptually superior to many of the trending energy production technologies due to their remarkably promising efficiency, environmental friendliness and cost. The accurate simulation of this combustion is very important because the operating conditions are very challenging to its experimentation. Hence, the current work focuses on identifying various thermal, transport, chemical kinetic models, investigating various fundamental characteristics and verifying the validity of important underlying modeling assumptions in focus to supercritical CO2 combustion. In the current work, various thermal and transport property models are identified based on accuracy, computational cost and ease of implementation for …

Process-Property-Microstructure Relationships In Laser-Powder Bed Fusion Of 420 Stainless Steel., Subrata Deb Nath

Electronic Theses and Dissertations

Laser-powder bed fusion (L-PBF) is an additive manufacturing technique for fabricating metal components with complex design and customized features. However, only a limited number of materials have been widely studied using L-PBF. AISI 420 stainless steel, an alloy with a useful combination of high strength, hardness, and corrosion resistance, is an example of one such material where few L-PBF investigations have emerged to date. In this dissertation, L-PBF experiments were conducted using 420 stainless steel powders to understand the effects of chemical composition, particle size distribution and processing parameters on ensuing physical, mechanical and corrosion properties and microstructure in comparison …

Low Temperature Desiccants In Atmospheric Water Generation., Sunil Gupta

Electronic Theses and Dissertations

Surging global water demand as well as changes to weather patterns and over exploitation of natural water sources, such as ground water, has made potable water a critical resource in many parts of the World already – one rapidly heading towards a crisis situation. Desalination has been adopted as a solution – this is however energy intensive and impractical for most of the developing countries - those most in need of water. A renewable source of energy is solar thermal and solar photovoltaic. A plentiful source of water is the humidity in the atmosphere. This research is to push the …

Selecting The Most Effective Energy Modeling Tool Based On A Project Requirement, Sodiq Akande

Electronic Theses and Dissertations

Building energy usage can be derived and controlled by performing building energy modeling. BEM can be performed using numerous software tools such as DesignBuilder, OpenStudio, EnergyPlus etc. These modeling tools can be sorted into three different modeling categories: Black-box, Gray-box and White-box. It is important for a modeler to be able to quickly select the proper tool from the proper category to meet the need of the project. To validate the method of categorizing tools, the three models generated using tools from each category and the modeling outputs required were compared. Each model was designed to estimate the amount of …

Optimization Of Heat Sinks In A Range Of Configurations., Archibald Allswell Amoako

Electronic Theses and Dissertations

In this study, different heatsink geometries used for electronic cooling are studied and compared to each other to determine the most efficient. The goal is to optimize heat transfer of the heat sinks studied in a range of configuration based on fin geometry. Heat sinks are thermal conductive material devices designed to absorb and disperse heat from high-temperature objects (e.g. Computer CPU). Common materials used in the manufacturing of heat sinks are aluminum and copper due to their relatively high thermal conductivity and lightweight [1]. Aluminum is used as the material for the heatsinks studied in this research project. To …

Ignition Studies Of Oxy-Syngas/Co2 Mixtures Using Shock Tube For Cleaner Combustion Engines, Samuel Barak

Electronic Theses and Dissertations

In this study, syngas combustion was investigated behind reflected shock waves in order to gain insight into the behavior of ignition delay times and effects of the CO2 dilution. Pressure and light emissions time-histories measurements were taken at a 2 cm axial location away from the end wall. High-speed visualization of the experiments from the end wall was also conducted. Oxy-syngas mixtures that were tested in the shock tube were diluted with CO2 fractions ranging from 60% - 85% by volume. A 10% fuel concentration was consistently used throughout the experiments. This study looked at the effects of changing the …

Simulation Of An Ethylene Flame With Turbulence, Soot And Radiation Modeling, Santu Golder

Electronic Theses and Dissertations

This thesis will investigate soot models that are available in commercial codes. We will look at the effect of turbulence models, gravity, soot models and radiation. Simulations will be compared to Coppalle and Joyeux [1]. The flame is an ethylene air diffusion flame at a Reynolds number of 5700. Simulations show the SST turbulence model, one-step soot model and Rosseland radiation model including gravity agree well with experimental data (temperature and soot). Flamelet soot modeling from Carbonell et al. [2] and flamelet radiation modeling from Doom [3] has been incorporated and compared as well.

Simulations Of Impinging Jet With A Range Of Configuration, Devansh Singh

Electronic Theses and Dissertations

Impinging jet technique is widely increasing across the globe due to its ability to produce high heat and mass transfer as compared to other traditional methods. Three cases of impinging jets related to cooling technologies for a gas turbine were investigated. The first case involves a single jet impinging on a flat plate. The second case has an array of jets impinging on a curved surface. The third case deals with simulating impinging jet in crossflow. The first case was used for validation and shows the effect of mesh and inlet boundary conditions. After careful observation, it was seen that …

Effect Of Non-Uniform Air-Side Velocity Distribution On Heat Transfer Model Predictions For Microchannel Condenser., Zachary Chapin

Electronic Theses and Dissertations

This is a study of the effects on heat transfer capacity predictions of microchannel condensers when airflow is maldistributed due to the shape of the condenser. The three shapes investigated in this study are flat, U-shape and roll. Each coil was tested in a water calorimeter and those results were compared to the model prediction. The model prediction was calculated using CoilDesigner™ modeling software with standard correlations. Using the uniform airflow assumption, the model over predicted the heat capacity measured in the calorimeter by 5-11% depending on the coil and inlet conditions. The local airflow velocity was measured using a …

Oscillating Heat Pipe Performance With Evaporator Section Modifications, Mitchell Hoesing

Electronic Theses and Dissertations

The continuous development of electronic components to become faster and smaller has led to an increasing problem with thermal management. Thermal management ensures that the component operating temperatures are within a safe range, which maintains performance and improves reliability and lifespan. Traditional thermal management devices, such as the extruded-fin heat sink, are incapable of maintaining the safe operating temperature range for current and future high heat flux cooling applications. A device that has the capability to meet this growing need is the oscillating heat pipe. Oscillating heat pipes (OHPs) are passive, two-phase cooling devices that have been shown to transfer …

Evaluation Of Two-Phase Evaporation Pressure Drop Correlations For Low Refrigerant Mass Flux., Anna Fenko

Electronic Theses and Dissertations

This study was conducted to evaluate three currently popular two-phase pressure drop models for extremely low velocity refrigerant flow through smooth circular evaporators in household refrigeration systems. Experimental data was taken at mass fluxes under 70 kg/m²s for two refrigerants, R134A and R600A, internal diameters of aluminum evaporators ranging from 0.186 to 0.317 inches, U-bend internal radii ranging from 0.342 to 0.750 inches in horizontal and vertical orientations of evaporators. The geometry of the samples closely resembled a commonly used serpentine shape with multiple U-bends experiencing both, up- and down-flow of the refrigerant. Two empirical models, Müller-Steinhagen & …

I. Improved Ice Meltage In Ice Boxes; Ii. Temperature Control In Tents - Winter Phase., Robert Beaman Duggan

Electronic Theses and Dissertations

This thesis consists of two parts: Improved Ice Meltage in Ice Boxes; Temperature Control in Tents - Winter Phase. Improved ice meltage in the Progress refrigerator is discussed in the first part of the thesis. This portion of the work shows that satisfactory refrigerator temperatures and flat ice meltage could not be obtained simultaneously when using V-shaped ice racks, although they could be obtained separately; however, the basket-type chamber offers greater possibilities of obtaining proper temperatures and meltage characteristics. Series of tests are discussed and conclusions drawn from the results. In the second part of the thesis, a method of …