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Articles 1 - 14 of 14
Full-Text Articles in Mechanical Engineering
Carbon Dioxide Gasification Of Biochar: A Study On Utilizing Captured Co2 To Mitigate Greenhouse Gas Emission And Improving Carbon Conversion Efficiency, Nnamdi Ofuani
Electronic Theses and 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
Mathematical Modeling Of Coupled Heat And Mass Transfer In Metal-Hydride Hydrogen Storage Systems, Muhammad Hasnain
Electronic Theses and 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 A Surrogate Fuel Based On Fischer-Tropsch Gtl And Ctl In Cvcc, Idi And Di Compression Ignition Engines, Amanda C. Weaver
Investigations Of A Surrogate Fuel Based On Fischer-Tropsch Gtl And Ctl In Cvcc, Idi And Di Compression Ignition Engines, Amanda C. Weaver
Electronic Theses and 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, …
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
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
Electronic Theses and 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 …
Cfd And Heat Transfer Analysis Of Rocket Cooling Techniques On An Aerospike Nozzle, Geoffrey Sullivan
Cfd And Heat Transfer Analysis Of Rocket Cooling Techniques On An Aerospike Nozzle, Geoffrey Sullivan
Electronic Theses and 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 …
Analysis Of Bio-Alcohols With Mie-Scattering And Ltc For Lowered Emissions In Pcci, Cesar E. Carapia
Analysis Of Bio-Alcohols With Mie-Scattering And Ltc For Lowered Emissions In Pcci, Cesar E. Carapia
Electronic Theses and 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 …
Analytical Modeling Of A Novel Elastohydrodynamic Seal Design For Supercritical Co2 Power Cycles, Ikenna C. Ejiogu
Analytical Modeling Of A Novel Elastohydrodynamic Seal Design For Supercritical Co2 Power Cycles, Ikenna C. Ejiogu
Electronic Theses and 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 …
Thermal Performance Of Sierpinski Carpet Fractal Fins At Various Angles Of Inclination In A Natural Convection Environment, Haidar Jamil Khalil
Thermal Performance Of Sierpinski Carpet Fractal Fins At Various Angles Of Inclination In A Natural Convection Environment, Haidar Jamil Khalil
Electronic Theses and 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 …
Investigation Of The Performance And Emissions Characteristics Of Dual Fuel Combustion In A Single Cylinder Idi Diesel Engine, Johnnie L. Williams Jr
Investigation Of The Performance And Emissions Characteristics Of Dual Fuel Combustion In A Single Cylinder Idi Diesel Engine, Johnnie L. Williams Jr
Electronic Theses and 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
Electronic Theses and 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 …
Natural Convection Heat Transfer Of Inclined Sierpinski Carpet Fractal Fins, Luke A. Fussell
Natural Convection Heat Transfer Of Inclined Sierpinski Carpet Fractal Fins, Luke A. Fussell
Electronic Theses and 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 …
Computational Fluid Dynamics Modeling Of The Effects Of Water Injection In A Diesel Engine, Rabun Z. Wallace
Computational Fluid Dynamics Modeling Of The Effects Of Water Injection In A Diesel Engine, Rabun Z. Wallace
Electronic Theses and 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
Computational Analysis To Enhance Laminar Flow Convective Heat Transfer Rate In An Enclosure Using Aerosol Nanofluids, Andrew Hudson
Electronic Theses and 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
Numerical Simulation Of Natural Convection In Rectangular Enclosures Of Varying Aspect Ratios And Its Feasibility In Environmental Impact Management Studies, Charles R. Walker
Electronic Theses and 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 …