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Full-Text Articles in Mechanical Engineering

Towards Sustainable Production Of Chemicals And Fuels From The Fast Pyrolysis Of Waste Polyolefin Plastics, Ulises Gracida Alvarez Jan 2019

Towards Sustainable Production Of Chemicals And Fuels From The Fast Pyrolysis Of Waste Polyolefin Plastics, Ulises Gracida Alvarez

Dissertations, Master's Theses and Master's Reports

The increasing amount of plastic waste (PW) generation has become an important concern due to the leveled-off recycling rates. Therefore, governmental agencies around the world, including state governments in the United States, have proposed initiatives to minimize the amount of PW that is landfilled and encourage recycling or energy recovery. Circular economy is a strategy that attempts on reusing PW to produce new polymers while avoiding its disposal and the use of virgin material. Chemical recycling raises an interesting technology prospect due to the potential reduction of pollutant emissions and the establishment of a circular economy through the production of ...


Design And Preliminary Evaluation Of A Supercritical Carbon Dioxide Brayton Cycle For Solar Dish Concentrator Clean Energy Production, Danielle Nobles-Lookingbill Dec 2018

Design And Preliminary Evaluation Of A Supercritical Carbon Dioxide Brayton Cycle For Solar Dish Concentrator Clean Energy Production, Danielle Nobles-Lookingbill

UNLV Theses, Dissertations, Professional Papers, and Capstones

As we move toward energy independence and more ambitious clean energy goals, solar energy research must push the efficiency limits of traditional energy generation systems. Increases in efficiency can be achieved by increasing the hot temperature of the power cycle. Recent research demonstrates the potential for increased efficiency and a vastly smaller component size when supercritical carbon dioxide Brayton power cycles are used. Concentrated solar and nuclear heat sources are capable of achieving the high working fluid temperatures needed for significant efficiency gains. This NSF EPSCoR funded, experimental research system is designed to exploit the uniquely immense solar irradiance of ...


Non-Covalent Functionalization Of Graphene Films For Uniform Nanoparticle Deposition Via Atoic Layer Deposition, Ty Seiwert May 2018

Non-Covalent Functionalization Of Graphene Films For Uniform Nanoparticle Deposition Via Atoic Layer Deposition, Ty Seiwert

Mechanical Engineering Undergraduate Honors Theses

Graphene functionalized with platinum (Pt) and palladium (Pd) has proven to be highly effective as a hydrogen sensor. Deposition methods such as Atomic layer deposition (ALD) can be further enhanced by pretreating the graphene with a non-covalent surfactant prior to nanoparticle deposition. In this study, graphene-based sensing devices will be fabricated by ALD deposition. The graphene will be non-covalently functionalized using sodium dodecyl sulfate (SDS) anionic surfactant prior to ALD deposition. The aim of this study is to test the deposition pattern achieved by varying the amount of time that graphene is treated with the SDS surfactant. Initially, ALD deposition ...


Effectiveness Of Biocide Substitution And Management Plan Implementation For The Control Of, Adelmarie Bones Mar 2018

Effectiveness Of Biocide Substitution And Management Plan Implementation For The Control Of, Adelmarie Bones

Graduate Theses and Dissertations

After the notorious outbreak and discovery of Legionella bacteria in 1976, the waterborne pathogen was added to the list of disease-causing agents associated with the built environment. Legionella pneumophila was discovered when it was identified as the agent that caused 34 deaths and an outbreak of pneumonia-like symptoms in several attendees of the 1976 American Legion Convention held in Philadelphia (OSHA, 2017).

Recently published data from the year 2015 reported more than 6,000 Legionnaires’ cases identified in the United States (CDC, 2016). This is a concerning number given that one in every ten infected persons will die of the ...


An Examination Of Ash Elutriation From A Fluidized Bed Regenerator, Dane Erickson Jan 2018

An Examination Of Ash Elutriation From A Fluidized Bed Regenerator, Dane Erickson

Graduate Theses and Dissertations

The danger of climate change looms in the minds of researchers across the world. To combat this threat, many have focused efforts on the development of clean energy. In this study, the renewable resource that is investigated is biomass, specifically red oak. Energy can be extracted from biomass by fast pyrolysis, where the feedstock is rapidly heated within a reactor to approximately 500℃ in the absence of oxygen. This produces biochar, ash, and condensable gases that, once cooled, become a bio-oil. To optimize economic feasibility, the process must operate continuously. This presents a problem—the presence of ash as a ...


Investigation Of Fundamental Transport And Physicochemical Phenomena In Lignocellulosic Fast Pyrolysis, Jordan A. Tiarks Jan 2018

Investigation Of Fundamental Transport And Physicochemical Phenomena In Lignocellulosic Fast Pyrolysis, Jordan A. Tiarks

Graduate Theses and Dissertations

Fast pyrolysis of biomass has the potential for high-yield production of valuable fuels and chemicals from renewable biological and agricultural waste feedstocks. Optimization of this technology is dependent on developing a deeper understanding of the complex transport and kinetic phenomena which drive product formation. In this dissertation, direct, time-resolved imaging of feedstock degradation and product formation mechanisms for the pyrolysis of whole biomass and several of its components has been made inside an optically accessible pyrolysis reactor. The reactor thermal and transport characterization allows the determination of dominant mechanisms of pyrolysis product formation in the multiphase reacting environment. This novel ...


Techno-Economic Analysis Of Biochemicals And Biofuels Production Via Thermal And Electrochemical Processes, Denis Bbosa Jan 2018

Techno-Economic Analysis Of Biochemicals And Biofuels Production Via Thermal And Electrochemical Processes, Denis Bbosa

Graduate Theses and Dissertations

Climate change is leading to concerning fluctuations in weather patterns mainly due to anthropogenic activities such as deforestation and burning of fossil fuels which are and will affect different sectors such as food chains, wildlife and most importantly the human life. The upcoming generations must be left with an environment worth to live in thus humans must intervene to reduce the emissions of greenhouse gases and that is why sustainable means must be used to provide clean energy and renewable-based chemicals. For the U.S., the USDOE and USDA proposed a 25% and 20% vision for biomass-based chemicals and fuels ...


Dust Control Examination Using Computational Fluid Dynamics Modeling And Laboratory Testing Of Vortecone And Impingement Screen Filters, Ashish R. Kumar Jan 2018

Dust Control Examination Using Computational Fluid Dynamics Modeling And Laboratory Testing Of Vortecone And Impingement Screen Filters, Ashish R. Kumar

Theses and Dissertations--Mining Engineering

Heavy industries, such as mining, generate dust in quantities that present an occupational health hazard. Prolonged exposure to the respirable dust has been found to result in many irreversible occupational ailments in thousands of miners. In underground mining applications, a variety of scrubbing systems are used to remove dust near the zones of generation. However, the wire-mesh type fibrous screens in the flooded-bed dust scrubbers used on continuous miners, are prone to clogging due to the accumulation of dust particles. This clogging results in a reduced capture efficiency and a higher exposure to the personnel. This research establishes the Vortecone ...


Automated Venetian Blinds And Lighting Integrated Into Office Building Automation Systems: Full-Scale Testing And Economic Analysis, Niraj Kunwar Jan 2018

Automated Venetian Blinds And Lighting Integrated Into Office Building Automation Systems: Full-Scale Testing And Economic Analysis, Niraj Kunwar

Graduate Theses and Dissertations

The application of interior, dynamically-operated venetian blinds in commercial buildings has been widely considered a promising opportunity to simultaneously save lighting and heating, ventilation and air conditioning (HVAC) energy, utilize natural daylight, and maintain visual comfort for occupants. Research in recent years, however, has focused mostly on simulation-based efforts to assess the impact of dynamic venetian blinds on daylighting, occupant comfort, and energy performance. What is lacking is the insight from full-scale experimental testing data, and the use of this data to validate the simulation and model-based findings in terms of energy and economic savings. This study thus assesses the ...


Pressure-Driven Stabilization Of Capacitive Deionization, Landon S. Caudill Jan 2018

Pressure-Driven Stabilization Of Capacitive Deionization, Landon S. Caudill

Theses and Dissertations--Mechanical Engineering

The effects of system pressure on the performance stability of flow-through capacitive deionization (CDI) cells was investigated. Initial data showed that the highly porous carbon electrodes possessed air/oxygen in the micropores, and the increased system pressure boosts the gases solubility in saline solution and carries them out of the cell in the effluent. Upon applying a potential difference to the electrodes, capacitive-based ion adsorption occurs in competition with faradaic reactions that consume oxygen. Through the addition of backpressure, the rate of degradation decreases, allowing the cell to maintain its salt adsorption capacity (SAC) longer. The removal of oxygen from ...


Experimental Evaluation Of Uranyl Transport Into Mesoporous Silica Gel Using Fluorescence, Brandon M. Dodd Jan 2018

Experimental Evaluation Of Uranyl Transport Into Mesoporous Silica Gel Using Fluorescence, Brandon M. Dodd

Theses and Dissertations

This research investigated parameters that can affect the use of nanoporous silica gel as a media for accumulating a detectable amount of uranium. The unique fluorescence of the Uranyl (UO22+) ion was used to evaluate the transport kinetics and accumulation within silica gel in a static fluid and under pressure driven flow. The addition of fluid flow decreased the time constant from on the order of an hour to approximately 2s with a very low fluid velocity of 0.36cm/s. The 0.36cm/s fluid velocity was found to be the critical velocity above which there was ...


Offshore Wind Energy: Simulating Local Offshore Wind Turbine, Ian P. Aquino Jan 2018

Offshore Wind Energy: Simulating Local Offshore Wind Turbine, Ian P. Aquino

Mechanical & Aerospace Engineering Theses & Dissertations

Dominion Virginia Energy is looking at the possible creation of an offshore wind plant as a renewable source of electricity to be located off the coast of Virginia Beach. This thesis reports on a computer simulation based on local wind conditions and possible single wind turbine installation.

The National Buoy Data Center keeps records of the local wind conditions gathered in real time and available to the public. These data give a general overview of the wind conditions in Virginia Beach which is used to simulate atmospheric boundary layer (ABL) flow conditions and is subsequently used as input data for ...


A Framework For Isogeometric-Analysis-Based Design And Optimization Of Wind Turbine Blades, Austin Herrema Jan 2018

A Framework For Isogeometric-Analysis-Based Design And Optimization Of Wind Turbine Blades, Austin Herrema

Graduate Theses and Dissertations

Typical wind turbine blade design procedures employ reduced-order models almost exclusively for early-stage design; high-fidelity, finite-element-based procedures are reserved for later design stages because they entail complex workflows, large volumes of data, and significant computational expense. Yet, high-fidelity structural analyses often provide design-governing feedback such as buckling load factors. Mitigation of the issues of workflow complexity, data volume, and computational expense would allow designers to utilize high-fidelity structural analysis feedback earlier, more easily, and more often in the design process. Thus, this work presents a blade analysis framework which employs isogeometric analysis (IGA), a simulation method that overcomes many of ...


Automated Cfd Optimization To Maximize Wind Farms Performance And Land Use, Rafael Valotta Rodrigues Jan 2018

Automated Cfd Optimization To Maximize Wind Farms Performance And Land Use, Rafael Valotta Rodrigues

Electronic Theses and Dissertations

In this research, a computational system was designed to analyze and optimize the layout of wind farms under variable operational conditions. At first, a wind turbine computational fluid dynamic (CFD) model was developed covering the near wake. The near wake flow field was validated against near wake velocity data from the MEXICO experiment. The CFD simulation demonstrated that the tip speed ratio and the pitch angle greatly influence the near wake behavior, affecting the velocity deficit and the turbulence intensity profile in this region. The CFD model was extended to cover the far wake, aiming to become a computational tool ...


Experimental Study Of High-Temperature Range Latent Heat Thermal Energy Storage, Chatura Wickramaratne Nov 2017

Experimental Study Of High-Temperature Range Latent Heat Thermal Energy Storage, Chatura Wickramaratne

Graduate Theses and Dissertations

Among all thermal energy storage (TES) systems, latent heat thermal energy storage (LHTES) attracts high interest due to its high energy density and high exergetic efficiency. Due to the high enthalpy of fusion and low cost, inorganic salts are becoming popular as phase change materials and are used as the storage media in LHTES systems. The main drawbacks for the inorganic salts are their low thermal conductivity and high reactivity above 500°C. Therefore, designing a cost-effective containment at these conditions with longevity is a challenge. Macro-encapsulation of the PCM is one way to solve both the PCM containment issue ...


Torrefaction Kinetics Of Hemp Hurds, An Emerging Agricultural Byproduct, In A Small Retort, Tel Jensen Sep 2017

Torrefaction Kinetics Of Hemp Hurds, An Emerging Agricultural Byproduct, In A Small Retort, Tel Jensen

Civil and Environmental Engineering Undergraduate Honors Theses

As knowledge concerning the consequences of unsustainable energy sources and agricultural practices grows, development of low-impact alternatives to both becomes more important. Sustainable sources of biomass offer solutions to both problems. This study characterized the reaction kinetics of torrefying an agricultural byproduct, the woody interior of hemp stems, or hurds. Torrefaction was carried out at 250 °C in small and simple retorts made of galvanized steel pipe. A first-order model most closely approximated the reaction. A sensitivity analysis was performed and the data was adjusted to correct for three potential sources of error, and regressed to find the best fit ...


Numerical Study Of Thermal Performance Improvement By Novel Structures In The Building Energy Storage Systems, Junling Xie Aug 2017

Numerical Study Of Thermal Performance Improvement By Novel Structures In The Building Energy Storage Systems, Junling Xie

Theses and Dissertations

In this work, numerical studies were conducted to investigate the effectiveness of two fin-like novel structures used for heat-transfer enhancement in two building energy storage systems including thermal energy storage and battery energy storage.

Firstly, thin layer ring structure was numerically investigated for thermal performance improvement in the thermal energy storage. From the results obtained in this study, the area ratio can be increased by 4% when using the thin layer ring during the same time period. The thin layer ring structure can shorten ice formation period and increase its efficiency. Further study was conducted for the factorial analysis of ...


An Economic Analysis Of Residential Photovoltaic Systems With And Without Energy Storage, Rodney Moses Kizito Aug 2017

An Economic Analysis Of Residential Photovoltaic Systems With And Without Energy Storage, Rodney Moses Kizito

Theses and Dissertations

Residential photovoltaic (PV) systems serve as a source of electricity generation that is separate from the traditional utilities. Investor investment into residential PV systems provides several financial benefits such as federal tax credit incentives for installation, net metering credit from excess generated electricity added back to the grid, and savings in price per kilowatt-hour (kWh) from the PV system generation versus the increasing conventional utility price per kWh. As much benefit as stand-alone PV systems present, the incorporation of energy storage yields even greater benefits. Energy storage (ES) is capable of storing unused PV provided energy from daytime periods of ...


Pore Resolved Simulations Of Char Particle Gasification, Greg Hingwah Fong Jul 2017

Pore Resolved Simulations Of Char Particle Gasification, Greg Hingwah Fong

Master's Theses (2009 -)

Coal is a significant source of energy in today’s world and many studies have been conducted in order to better understand and optimize its use. To address greenhouse effects associated with coal combustion, cleaner methods for harnessing its energy are being explored. One such method is gasification, a process which converts coal into syngas, a mixture consisting primarily of H2 and CO. Syngas can be used to generate electricity or to produce hydrocarbons that can be used as fuels. To better understand and optimize the process, simulations can be used to study the gasification of individual porous char particles ...


Micro-Spi Sediment Profile Imaging Micro-Inspector, Andrew P. Corvin, Caleb T. Davies, Matt R. Ferrari Jun 2017

Micro-Spi Sediment Profile Imaging Micro-Inspector, Andrew P. Corvin, Caleb T. Davies, Matt R. Ferrari

Mechanical Engineering

This project was proposed by Dr. Brian Paavo through a desire to more easily study the benthic sediment layers of the ocean. To do so, he asked us to build a simple and compact machine for use in sediment profile imagery (SPI). Although devices like this already exist, they are all large scale devices that require a ship with a crane to deploy, which is expensive and time consuming. Instead, he desired a “micro” SPI, which is capable of being deployed from a small vessel that can easily navigate shallow waters. Our interpretation of these requirements was as follows: a ...


Thermo-Mechanical Modeling And Parametric Analysis Of Lithium-Ion Battery, Abhishek Sarkar Jan 2017

Thermo-Mechanical Modeling And Parametric Analysis Of Lithium-Ion Battery, Abhishek Sarkar

Graduate Theses and Dissertations

Lithium-ion battery electrodes tend to fracture due to extensive mechanical stress and/or thermally fail by due to overheating. In our present research, we have studied the mechanical and thermal aspect of lithium battery electrodes. Two significant tasks were performed for this project. First, a numerical model was developed for analyzing the crack propagation during lithiation of crystalline silicon. We investigated the influence of mechanical properties of lithiated silicon on the fracture of silicon nanoparticles during lithiation. A chemo-mechanical model was used to determine the lithium distribution and associated stress states during lithiation. The concentration gradient of lithium and an ...


Pretreatment Optimization Methods For Increased Sugar Yields From Biomass Pyrolysis, Kayla Elizabeth Johnson Jan 2017

Pretreatment Optimization Methods For Increased Sugar Yields From Biomass Pyrolysis, Kayla Elizabeth Johnson

Graduate Theses and Dissertations

In the search for a renewable energy source that could replace petroleum and other nonrenewable energy sources, pyrolysis of biomass is a hopeful alternative and pretreatment could further improve its potential. There are several possible routes for pretreating lignocellulosic biomass, but many need further refining before becoming economical. The main obstacle for the conversion of biomass to high quality products is the presence of alkali and alkaline earth metals (AAEMs) that are known to impair cellulose decomposition to levoglucosan and promote char, water, and light oxygenate formation. One pretreatment option is to remove the AAEMs from the biomass by washing ...


What Limits The Yield Of Levoglucosan During Fast Pyrolysis Of Cellulose?, Juan Sebastian Proano-Aviles Jan 2017

What Limits The Yield Of Levoglucosan During Fast Pyrolysis Of Cellulose?, Juan Sebastian Proano-Aviles

Graduate Theses and Dissertations

The pyrolysis of cellulose to form levoglucosan is investigated in this study. Although the stoichiometric yield of levoglucosan from the pyrolysis of cellulose is expected to be 100%, only about 60 wt.% yields are reported in the literature.[1–3] Several possible reasons for this limitation are investigated through experiments in micropyrolyzers and computational studies on the depolymerization of cellulose. Heat and mass transfer limitations in an experimental apparatus is one possible limitation on the yield of levoglucosan. Repolymerization of condensed phase reaction intermediates could prevent the formation and release of volatile levoglucosan. Thermohydrolysis of pyrolyzing cellulose to form non-volatile ...


Study Of Periodical Flow Heat Transfer In An Internal Combustion Engine, Xi Luo Jan 2017

Study Of Periodical Flow Heat Transfer In An Internal Combustion Engine, Xi Luo

Wayne State University Dissertations

In-cylinder heat transfer is one of the most critical physical behaviors which has a direct influence on engine out emission and thermal efficiency for IC engine. In-cylinder wall temperature has to be precisely controlled to achieve high efficiency and low emission. However, this cannot be done without knowing gas-to-wall heat flux. This study reports on the development of a technique suitable for engine in-cylinder surface temperature measurement, as the traditional method is “hard to reach.” A laser induced phosphorescence technique was used to study in-cylinder wall temperature effects on engine out unburned hydrocarbons during the engine transitional period (warm up ...


Analysis And Modeling Of Structure Formation In Granular And Fluid-Solid Flows, Eric James Murphy Jan 2017

Analysis And Modeling Of Structure Formation In Granular And Fluid-Solid Flows, Eric James Murphy

Graduate Theses and Dissertations

Granular and multiphase flows are encountered in a number of industrial processes with particular emphasis in this manuscript given to the particular applications in cement pumping, pneumatic conveying, fluid catalytic cracking, CO2 capture, and fast pyrolysis of bio-materials. These processes are often modeled using averaged equations that may be simulated using computational fluid dynamics. Closure models are then required that describe the average forces that arise from both interparticle interactions, e.g. shear stress, and interphase interactions, such as mean drag. One of the biggest hurdles to this approach is the emergence of non-trivial spatio-temporal structures in the particulate phase ...


Stationary Nonimaging Concentrators – A Comprehensive Study And Design Improvements, Srikanth Madala Dec 2016

Stationary Nonimaging Concentrators – A Comprehensive Study And Design Improvements, Srikanth Madala

UNLV Theses, Dissertations, Professional Papers, and Capstones

Most places on our planet receive an annual average radiation between 800-1000 W/m2. In the man-made world, this radiation is largely incident on stationary structures such as buildings, roads, monuments, bridges etc. Moreover, in the natural world also, there are large tracts of barren land which can be put to good use given their solar energy potential. The vision of the current research is to concentrate all this available solar energy to a more readily usable form. Therefore, stationary nonimaging solar concentrator technologies are sought after. This dissertation work is an exhaustive research on the nonimaging concentrating mechanisms with ...


Modeling Pyrolysis Of Large Coal Particles With Many Species, Jianqing Li Oct 2016

Modeling Pyrolysis Of Large Coal Particles With Many Species, Jianqing Li

Master's Theses (2009 -)

Coal currently supplies 40% of the world’s electricity needs, and is one of the most important energy sources. As the initial stage of coal combustion, pyrolysis is a thermal decomposition process which converts coal into light gases and tars, which are subsequently consumed in combustion reactions, as well as solid char. Recently there has been interest in using slow pyrolysis as a stand-alone process for the production of chemicals and fuels from large (mm-scale) coal particles. Simulations can be used to efficiently study the impact of pyrolysis conditions on gas, tar and char yields, as well as gas and ...


Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood Aug 2016

Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood

Doctoral Dissertations

An estimate of the United States wind potential conducted in 2011 found that the energy available at an altitude of 80 meters is approximately triple the wind energy available 50 meters above ground. In 2012, 43% of all new electricity generation installed in the U.S. (13.1 GW) came from wind power. The majority of this power, 79%, comes from large utility scale turbines that are being manufactured at unprecedented sizes. Existing wind plants operate with a capacity factor of only approximately 30%. Measurements have shown that the turbulent wake of a turbine persists for many rotor diameters, inducing ...


How Can Occupancy Modeling And Occupancy Sensors Reduce Energy Usage In Academic Buildings: An Application Approach To University Of San Francisco, Paloma R. Duong May 2016

How Can Occupancy Modeling And Occupancy Sensors Reduce Energy Usage In Academic Buildings: An Application Approach To University Of San Francisco, Paloma R. Duong

Master's Projects and Capstones

Buildings are amongst the highest energy consumers relative to industry and transportation. They account for 40% of the world’s energy consumption, due to the need for lighting, equipment, heating, cooling and ventilation. Academic buildings are multi-purpose buildings that create a challenge on energy reduction. Most are old and have fixed occupancy schedules, resulting in high energy consumption because these buildings experience significant occupancy variation throughout the day. Five academic buildings were analyzed; their building information, energy consumption data and methods to project energy savings have been analyzed. The case studies presented different strategies on predicting energy savings, but these ...


Haul Truck Tires Recycling, Jessica N. Lizarazu May 2016

Haul Truck Tires Recycling, Jessica N. Lizarazu

Chemical Engineering Undergraduate Honors Theses

The disposal of large Off-the-Road (OTR) tires is an increasingly important concern. These tires can weigh up to 8,450 pounds with an overall diameter and width of approximately 140.7 inches and 45.1 inches respectively. OTR tires are used for mining vehicles such as haul trucks, wheel loaders, backhoes, graders, and trenchers. These new tires cost between $38,000 and $50,000 each, depending on multiple factors including oil prices and the cyclical nature of the industry. Haul trucks contain six tires per vehicle, and mines replace these tires around every 9-12 months. Statistics regarding discarded OTR tires ...