Heat Transfer, Combustion Commons^™

Comprehensive Analysis Of Spray Development And Low Temperature Combustion Characteristics In A Cvcc With Nvh Of Renewable Aerospace Fuels: Hefa & Ft Synthetic Kerosene (S8) Compared To Jet-A & Ulsd, Coleman Norton

Honors College Theses

A comprehensive analysis was conducted to research the viability of Hydroprocessed Esters and Fatty Acids (HEFA) and S8 Synthetic Kerosene fuels as a drop-in replacement for conventional petroleum-based fuels, Jet-A and ULSD (Ultra Low Sulfur Diesel). Global transportation remains heavily dependent on liquid fossil fuels, while renewable aerospace fuels offer a promising pathway to reducing life cycle greenhouse gas emissions and pollution. However, the combustion performance and long-term feasibility of these fuels remain insufficiently characterized. This study performed a thorough assessment of each fuel's thermophysical and combustion properties. Thermophysical characterization encompassed viscosity, freezing point, energy density, spray atomization, and volatility. …

Multiphysics Modeling Of Solid Oxide Fuel Cells For Gradient Minimization And Inductive Loop Analysis In Impedance Spectroscopy Using Machine Learning-Based Microstructural Property Estimation, Muhammad Usman Khan

College of Graduate Studies: Theses & Dissertations

Solid oxide fuel cells have significant advantages in renewable energy utilization due to their high efficiency, fuel flexibility, and low emissions. However, despite the numerous efforts of technology, thermal and current density gradients and impedance behavior fluctuations are still causing performance degradation. A combined computational framework that integrates machine learning and three-dimensional Multiphysics modeling is needed to investigate and optimize the performance of solid oxide fuel cells. A machine learning model, trained on synthetic microstructure data by percolation analysis, is used to predict important microstructural parameters like triple phase boundary density and geometric tortuosity. These are then employed in a …

An Investigative Study Of Thermal Fluid Properties When Introducing Metallic Nanoparticles Through A Heat Exchanging System, Levi P. Mckinney

College of Graduate Studies: Theses & Dissertations

Heat-exchanging systems are essential in applications ranging from automobiles to air-conditioning units, and ongoing improvements aim to enhance efficiency while reducing system size. Conventional coolant upgrades often rely on ethylene glycol, which increases thermal stability and lowers freezing point but reduces water’s inherent heat-transfer capability. Advances in nanotechnology provide an alternative approach: suspending nanoparticles in base fluids can significantly modify thermal properties, with some formulations exhibiting conductivity increases of up to 60%. This thesis examines the thermal and tribological performance of three working fluids—distilled water, a 50:50 water–ethylene glycol mixture, and the same mixture enhanced with Al₂O₃ nanoparticles. Distilled water …

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 …

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 …

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 …

Investigations Of A Surrogate Fuel Based On Fischer-Tropsch Gtl And Ctl In Cvcc, Idi And Di Compression Ignition Engines, Amanda C. Weaver

College of Graduate Studies: Theses & Dissertations

With the increase in availability, feedstocks, and properties of alternative fuels, compatibility issues emerge between current engine platforms often requiring a limit on the blend percentage of alternative fuel in conventional fuel or alteration to the engine platform. Two key metrics were identified, autoignition quality and lubrication characteristics, as vital for the proper function of a compression ignition engine, and if the blend of alternative fuels matches these two criteria for the diesel standard, then the resulting blend percentage can be considered as a viable alternative for complete replacement of conventional petroleum ULSD. Autoignition quality was matched using blends S-8, …

Investigation Of The Low-Temperature Combustion Phenomena Of A Fischer-Tropsch Synthetic Aerospace Fuel In A Constant Volume Combustion Chamber For Greenhouse Gas Reduction, Lily H. Parker

Honors College Theses

Greenhouse gases (GHG) have a harmful effect on our environment as they trap heat in the atmosphere accelerating climate change. As such, the Federal Aviation Administration’s 2025 strategic plan to reduce GHG emissions from air transportation. This call to action for a more environmentally friendly option highlights the importance of synthetic fuels as they are more sustainable compared to traditional fossil fuels. An investigation was conducted into the thermal-physical properties of Synthetic Fischer-Tropsch (F-T) Sustainable Aviation Fuels (SAF) and the Low Temperature Combustion (LTC). LTC is composed of the Low Temperature Heat Release (LTHR) and Negative Temperature Coefficient (NTC) region, …

Analytical Modeling Of A Novel Elastohydrodynamic Seal Design For Supercritical Co2 Power Cycles, Ikenna C. Ejiogu

College of Graduate Studies: Theses & Dissertations

Supercritical carbon dioxide (sCO₂) power cycles show great potential for higher plant efficiencies and power densities for a wide range of power generation applications such as fossil fuel power plants, nuclear power production, solar power, and geothermal power generation. sCO₂ leakage has been one of the main concerns in such applications, penalizing the cycle efficiencies. The effect of the seal leakage on the cycle efficiency could be as high as 0.65% for a utility sCO₂ power cycle. Therefore, there is a pressing need for effective sealing solutions to get the full benefit of sCO₂ power …

Investigations Of The Low Temperature Combustion Regions And Emissions Characteristics Of Aerospace F24 In A Constant Volume Combustion Chamber And A Common Rail Direct Injection Ci Engine, Richard C. Smith Iii

College of Graduate Studies: Theses & Dissertations

A study was conducted to investigate the low temperature combustion (LTC) regions of aerospace F24 and ULSD in the static setting of a CVCC and the dynamic setting of a CRDI research engine. This research is conducted to reduce in-cylinder emissions by understanding and implementing a technique to achieve an extended LTC. Emissions data for this study were collected during the operation of the CRDI research engine with a MKS 2030 FTIR and an AVL Microsoot 483. The parameters researched within the static setting of the CVCC included the determinations of the cool flames and NTC regions within the LTHR …

Analysis Of Bio-Alcohols With Mie-Scattering And Ltc For Lowered Emissions In Pcci, Cesar E. Carapia

College of Graduate Studies: Theses & Dissertations

An investigation was conducted on the optimal engine parameters for facilitating lower NOX and soot emissions of PCCI combustion with either ethanol or n-butanol. The PFI fuels selected were tested at loads of 3, 4, and 5 Bar IMEP for a total of 28 total combustion tests with variations made to the EGR% and boost pressure for each test in order to find the optimal emissions strategy. A Mie-scattering spray fuel analysis was also conducted on the three fuels to gain insight on their influence on combustion/emissions characteristics. It was found that ethanol had a greater average Sauter Mean Diameter …

Cfd And Heat Transfer Analysis Of Rocket Cooling Techniques On An Aerospike Nozzle, Geoffrey Sullivan

College of Graduate Studies: Theses & Dissertations

In recent years the development of rocket engines has been mainly focused on improving the engine cycle and creating new fuels. Rocket nozzle design has not been changed since the late 1960s. Recent needs for reliable and reusable rockets, as well as advancements in additive manufacturing, have brought new interest into the aerospike nozzle concept. This nozzle is a type of altitude adjusting nozzle that is up to 90% more efficient than bell nozzles at low altitudes and spends up to 30% less fuel. Since the nozzle body is submerged in the hot exhaust gasses it is difficult to keep …

Investigations Of The Negative Temperature Coefficient Region Of Sustainable Aviation Fuels For Mitigation Of Global Warming, Richard C. Smith Iii

Honors College Theses

An investigation was led to determine the correlations between the durations of Ignition Delay (ID), Combustion Delay (CD), Derived Cetane Number (DCN), Negative Temperature Coefficient (NTC), Low-Temperature Heat Release (LTHR) regions, ringing intensity, and precent mass burn, and the effect of blending the Fischer-Tropsch (F-T) synthetic aerospace fuel (SAF), iso-paraffinic kerosene (IPK), with petroleum derived Jet-A aerospace fuel on these regions. Neat blends of Jet-A and IPK and three by mass blends of the fuels will be researched. These blends include mass percentages of 75%Jet-A and 25%IPK (75Jet-A25IPK), 50%Jet-A 50%IPK (50Jet-A50IPK), and 25%Jet-A 75%IPK (25Jet-A75IPK). The study will utilize a …

A Study Of The Efficiency And Effectiveness Of The First Four Iterations Of Sierpinski Carpet Fractal-Like Fins At Increasing Angles In Natural Convection, Sophia N. Fleri

Honors College Theses

Fractal geometries have been found in several studies to increase a fin’s thermal performance. Both the reductions of volume and mass accompanied by an increase in performance are desirable to prevent malfunction of the device through passive heat dissipation. The Sierpinski carpet fractal pattern, beginning with a basic square geometry in which an increasing number of perforations are incorporated through each successive iteration, reduces the fin’s mass while increasing its surface area simultaneously; this increase in surface area increases the rate of heat transfer experienced across the fin. The first four iterations of the Sierpinski carpet pattern, each with identical …

Thermal Performance Of Sierpinski Carpet Fractal Fins At Various Angles Of Inclination In A Natural Convection Environment, Haidar Jamil Khalil

College of Graduate Studies: Theses & Dissertations

As technology advances, higher performance cooling systems are desired to meet numerous thermal management challenges. Extended surfaces, also known as heat sinks or fins, are commonly used to passively dissipate unwanted heat from mechanical and electrical systems. Fractal fins in accordance with the first four iterations (including a base iteration) of the Sierpinski carpet, manufactured from AL-5052, were studied along seven different inclinations from 0° (orientated perpendicular to the direction of gravity) to 90° (orientated parallel to the direction of gravity), in iterations of 15°. The purpose of study was to investigate the thermal performance of the first four fractal …

The Investigation Of Noise, Vibrations And Emissions Of Aero-Gas Turbine Combustion With Synthetic Kerosene Fuels, Margaret Kilpatrick

Honors College Theses

Climatic changes from aviation emissions are complex and include effects of greenhouse gases such as: CO2, NOx, and aerosols. For that reason, the objectives of this study were to investigate the noise, vibrations and emissions characteristics of synthetic kerosene combustion in an aerospace gas turbine to reduce the engine’s environmental impact. Sustainably produced synthetic kerosene is known for having low soot emissions due to little to no aromatics (compounds that create particle pollutants), and for being a sustainable alternative fuel source to imported oil. The noise and sound levels were collected using Bruel & Kjaer microphones to measure various mid …

Investigation Of The Performance And Emissions Characteristics Of Dual Fuel Combustion In A Single Cylinder Idi Diesel Engine, Johnnie L. Williams Jr

College of Graduate Studies: Theses & Dissertations

Restrictions in the allowable exhaust gas emissions of diesel engines has become a driving factor in the design, development, and implementation of internal combustion (IC) engines. A dual fuel research engine concept was developed and implemented in an indirect injected engine in order to research combustion characteristics and emissions for non-road applications. The experimental engine was operated at a constant speed and load 2400 rpm and 5.5 bar indicated mean effective pressure (IMEP). n-Butanol was port fuel injected at 10%, 20%, 30%, and 40% by mass fraction with neat ultra-low sulfur diesel (ULSD#2). Peak pressure, maximum pressure rise rates, and …

Reduced Exhaust Emissions Through Blending N-Butanol With Ultra Low Sulfur Diesel And Synthetic Paraffinic Kerosene In Reactivity Controlled Compression Ignition Combustion, Remi Gaubert

College of Graduate Studies: Theses & Dissertations

Increasing restrictions on the emitted exhaust emissions in diesel engines are becoming a more challenging task than in previous years. An electronic common rail fuel injection system and a port fuel injection (PFI) system were developed for an experimental engine to research dual fuel combustion. The experimental research was conducted at 1500 rpm and 4, 5, and 6 bar indicated mean effective pressure (IMEP). n-Butanol was port fuel injected at a 60% by mass fraction coupled with direct injection (DI) of three fuels, including ultra-low sulfur diesel (ULSD RCCI), a 50-50 wt-% blend of ULSD and butanol (ULSD-Bu RCCI), and …

Impact Of Flow Direction On Local Flow Behavior In Biologically-Inspired Flow Passages, Derrick Dewayne Herrin

Honors College Theses

ABSTRACT

A computational fluid dynamics model was utilized to study the effect of flow direction on local flow behavior in biologically-inspired microscale flow networks. Biologically-inspired flow networks have been found to offer numerous advantages when compared with parallel flow networks, particularly in thermal management applications. Flow behavior was examined for a range of bifurcation angles and laminar inlet Reynolds numbers. The computational model was validated with existing theoretical solutions and verified for grid independence. As the bifurcation angle increased, the pressure drop, and thus pumping power, across the biologically-inspired flow networks increased. In addition, as the inlet Reynolds number increased, …

Natural Convection Heat Transfer Of Inclined Sierpinski Carpet Fractal Fins, Luke A. Fussell

College of Graduate Studies: Theses & Dissertations

When designing extended surfaces for the thermal management of electronic devices in aerospace applications it is critically important to minimize mass. However, this can be difficult to achieve as the rate of heat dissipated is directly proportional to the surface area. Fortunately, when certain fractal geometries, like the Sierpinski carpet, are utilized in the design of extended surfaces an increase in surface area and simultaneous decrease in mass can be achieved. The thermal performance of fins inspired by the first four fractal iterations of the Sierpinski carpet pattern was experimentally examined in a natural convection environment. The fractal fins were …

Investigation Of The Thermal Performance Of Sierpinski Carpet Fractal Fins In A Natural Convection Environment, Jennifer P. Shaffer

Honors College Theses

This experimental investigation studies the thermal performance of the first four iterations of the Sierpinski carpet pattern in a natural convection environment. This particular fractal geometry is promising in that it increases the available surface area for heat transfer while simultaneously decreasing the mass of the system. This makes it a potentially advantageous design for fins or heat sinks, especially in aerospace applications where minimizing mass of the system is essential. The thermal performance was evaluated by comparing the efficiency, effectiveness, and effectiveness per unit mass for each fractal iteration. The results indicate that efficiency decreases with each fractal iteration …

Computational Fluid Dynamics Modeling Of The Effects Of Water Injection In A Diesel Engine, Rabun Z. Wallace

College of Graduate Studies: Theses & Dissertations

Water injection has been used in internal combustion engines for many years. It has been used to cool combustion temperatures, reduce emissions, and in some instances clean carbon buildup from the cylinder. Research has shown that the water to fuel mass ratio is most effective between 20-30%, so the upper and lower limit were used for simulations in Converge CFD. To validate the CFD model, a case without water injection was compared to experimental data from Sandia National Laboratory. The predicted in-cylinder pressure and heat release rate showed good agreement with the experimental data. Cases were run with the injection …

Computational Analysis To Enhance Laminar Flow Convective Heat Transfer Rate In An Enclosure Using Aerosol Nanofluids, Andrew Hudson

College of Graduate Studies: Theses & Dissertations

The current research intends to provide a starting point to effectively model aerosol heat transfer in a narrow, enclosed body. This research can lead to future modeling of nano fluids including their heat transfer characteristics and erosion effects on the walls of an enclosure. The model was developed using ICEM CFD for the mesh and FLUENT for the fluid flow modeling. Six different aspect ratio enclosures were developed to study the effects of varying aspect ratio. The natural convection of air was developed first to establish the appropriateness of the models being used. A mesh check was performed using one …

Numerical Simulation Of Natural Convection In Rectangular Enclosures Of Varying Aspect Ratios And Its Feasibility In Environmental Impact Management Studies, Charles R. Walker

College of Graduate Studies: Theses & Dissertations

Author's abstract: Numerical simulation was used to investigate natural convection in horizontal and vertical enclosures with and without an internal heat source. Natural convection in rectangular enclosures is found in many real-world applications. Included in these applications are the energy efficient design of buildings, operation and safety of nuclear reactors, solar collector design, passive energy storage, heat transfer across multi-pane windows, thermo-electric refrigeration and heating devices, and the design-for-mitigation of optical distortion in large-scale laser systems. Considering all these applications, especially controlling heat transfer in nuclear power plants, knowledge and research results of natural convection in enclosure play a vital …