Mechanical Engineering Commons^™

Dynamic Modeling And Extreme Tension Analysis Of Mooring System For A Floating Offshore Wind Turbine, Wei Ting Hsu

Electronic Theses and Dissertations

For offshore wind industry, exploiting the dynamic behaviors of mooring lines is of increasing importance in floating offshore wind turbine (FOWT) mooring system design. Currently, the design philosophy for structures and moorings is based on principles and practices adopted in offshore oil and gas, including mooring systems that are optimized for applications in deeper waters. However, the design of FOWT mooring systems is facing several challenges, including installation costs, the stability of light-weight minimalistic platforms, and shallow water depths (50-300m). The extreme tension in mooring lines of a light displacement platform in shallow water is dominated by snap loads. Hence …

Exploring Energy, Comfort, And Building Health Impacts Of Deep Setback And Normal Occupancy Smart Thermostat Implementation, Zachary Ethan Alderman

Graduate Theses and Dissertations

As smart thermostat adoption rates continue to increase, it becomes worthwhile to explore what unanticipated outcomes may result in their use. Specific attention was paid to smart thermostat impacts to deep setback and normal occupancy states in a variety of conditions while complying with the ventilation and temperature requirements of ASHRAE 90.2-2013. Custom weather models and occupancy schedules were generated to efficiently explore a combination of weather conditions, building constructions, and occupancy states. The custom modeling approach was combined with previous experimental data within the Openstudio graphics interface to the EnergyPlus building modeling engine. Results indicate smart thermostats add the …

Design And Validation Of An Experimental Setup To Study Single Phase Heat Transfer Enhancement Of Femtosecond Laser Processed Metallic Surfaces, Sarah Jane Wallis

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

In the present work, a single phase flow heat transfer experimental loop was designed with the intention of studying the effects of femtosecond laser surface processing (FLSP) on metallic surfaces with the specific goal of enhancing heat transfer in compact heat exchangers currently in use by NASA. This experimental setup went through two major design iterations which are detailed in this thesis. The first iteration consisted of a counterflow fluid-to-fluid heat exchanger, which measured overall heat transfer coefficients and pressure drops, where the overall heat transfer coefficient is defined in terms of the total thermal resistance to heat transfer between …

Energy Efficiency And Economic Feasibility Of An Absorption Air-Conditioning System Using Wet, Dry And Hybrid Heat Rejection Methods, Julia Aman, Paul Henshaw, David S-K Ting

Mechanical, Automotive & Materials Engineering Publications

In tropical and sub-tropical regions, air-conditioning systems account for the greatest electricity consumption and high water use. Solar-driven absorption cooling systems can conveniently reduce electricity consumption at need. The performance of this cooling system depends on the system’s heat rejection. A simulation was performed for a 15 kW single effect ammonia-water absorption cooling system driven by low temperature thermal energy and with three different heat rejection methods (wet cooling, dry cooling, and hybrid cooling). This hybrid cooling system uses wet cooling on the absorber and dry cooling on the condenser. The system performance and economics of the chiller with these …

Pollution Prevention In The Great Lakes Basin: Working With Pulp & Paper Manufacturers, Eugene Park

Journal of Environmental Sustainability

In response to growing concerns over persistent toxic substances in the Great Lakes, new initiatives are in place to address and mitigate pollutant loadings to these large natural waterbodies. With support from the U.S. Environmental Protection Agency and New York Department of Environmental Conservation, the New York State Pollution Prevention Institute (NYSP2I) worked with pulp & paper companies in the Great Lakes Basin in an effort to find solutions to reduce environmental impacts from this industry sector. Based on currently available EPA toolkits, NYSP2I developed and utilized an assessment tool called Lean, Energy, and Environment (LE2). Five different paper manufacturers …

Development, Energy, And Climate Change Policy: Enabling Sustainable Development Through Access To Energy, Robert J. Brecha

Biennial Conference: The Social Practice of Human Rights

Human rights, human development, and climate change clearly overlap in many ways. Development, as quantified by the Human Development Index (HDI), for example, has historically been strongly correlated with energy consumption. This fact is recognized in Sustainable Development Goal (SDG) 7, to “ensure access to affordable, reliable, sustainable and modern energy for all.” Currently the world is in the midst of a large wave of human migration, much of it involuntary and due to stymied development opportunities as well as political upheaval. Climate change will become, or already is, an exacerbating factor in migration dynamics.

A pertinent question is how …

A Strategic Development Of Alternative Fuel Initiation And Its Adaptation In A Developing Country: A Feasibility Study On Methanol Fuelled Domestic Passenger Ships In Indonesia, Eko Maja Priyanto

World Maritime University Dissertations

No abstract provided.

Analytical Assessment Of Port Energy Efficiency And Management .: A Case Study Of The Kenya Ports Authority, Maryam Mohamed Kidere

World Maritime University Dissertations

No abstract provided.

Optimising Energy Efficiency: Split Incentives In The Context Of The Implementation Of Seemp, Edwin Nii Oduah Mensah

World Maritime University Dissertations

No abstract provided.

A Decision Support System For Ship’S Energy Efficient Operation: Based On Artificial Neural Network Method, Yasser Bayoumy Abdelwahab Farag

World Maritime University Dissertations

No abstract provided.

Bubble-Pump-Driven Libr-H2o And Licl-H2o Absorption Air-Conditioning Systems, Julia Aman, Paul Henshaw, David S-K Ting

Mechanical, Automotive & Materials Engineering Publications

A thermally-driven bubble pump, powered by solar or waste heat energy, is a simple and efficient technique for lifting a liquid from lower to higher levels, after which it can flow by gravity. In this study, solar thermal driven pumps were incorporated in the solar collector as well as in the refrigerant cycle to provide a design of an air-conditioning system for a residential home that is independent of grid electricity. The crystallization challenge, low pressure, and low efficiency are the main downsides of bubble-pump-driven LiBr-H2O refrigeration systems, in comparison with other bubble-pump-driven diffusion absorption refrigeration systems. Therefore, a complete …

Prediction Of Solid Oxide Fuel Cell Performance Using Artificial Neural Network, M. A. Rafe Biswas, Kamwana N. Mwara

M. A. Rafe Biswas

Resilient And Real-Time Control For The Optimum Management Of Hybrid Energy Storage Systems With Distributed Dynamic Demands, Christopher R. Lashway

FIU Electronic Theses and Dissertations

A continuous increase in demands from the utility grid and traction applications have steered public attention toward the integration of energy storage (ES) and hybrid ES (HESS) solutions. Modern technologies are no longer limited to batteries, but can include supercapacitors (SC) and flywheel electromechanical ES well. However, insufficient control and algorithms to monitor these devices can result in a wide range of operational issues. A modern day control platform must have a deep understanding of the source. In this dissertation, specialized modular Energy Storage Management Controllers (ESMC) were developed to interface with a variety of ES devices. The EMSC provides …

Semi-Annual Program Progress Performance Report For University Transportation Systems Pppr#8, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

The major activity of the past reporting period has been the completing of the final project research reports. During the period, twelve projects (numbers 3, 7, 10, 14, 17, 9, 22, 4, 5, 13, 20 and 18) were completed and the final project reports forwarded to DOT and the required associated organizations. Two additional final reports (numbers 12 and 21) are close to being completed. Final reports for the other 4 remaining projects (numbers 2, 8, 11 and 15) are in various stages of completion. For this reporting period, EVTC researchers concluded 12 project final reports, authored one publication, made …

Note On The Rate And Energy Efficiency Limits For Additive Manufacturing, Timothy Gutowski, Sheng Jiang, Daniel Cooper, Gero Corman, Michael Hausmann, Jan-Anders Manson, Timo Schudeleit, Konrad Wegener, Matias Sabelle, Jorge Ramos-Grez, Dusan P. Sekulic

Mechanical Engineering Faculty Publications

We review the process rates and energy intensities of various additive processing technologies and focus on recent progress in improving these metrics for laser powder bed fusion processing of metals, and filament and pellet extrusion processing of polymers and composites. Over the last decade, observed progress in raw build rates has been quite substantial, with laser metal processes improving by about 1 order of magnitude, and polymer extrusion processes by more than 2 orders of magnitude. We develop simple heat transfer models that explain these improvements, point to other possible strategies for improvement, and highlight rate limits. We observe a …

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 …

The Development And Numerical Modelling Of A Representative Elemental Volume For Packed Sand, Ashraf Thabet

Electronic Thesis and Dissertation Repository

The motivation of this thesis is the development of simple microscopic-scale model (representative elemental volume; REV) that can be used to conduct flow and heat transfer simulations from which closure coefficients can be established for the volume-averaged transport equations for porous media (packed bed). The thesis provides a brief introduction to the computational technique adopted for the geometric generation of the REV (YADE), followed by a parametric study undertaken to reveal the minimum number of particles inside the REV that are required to mimic the appropriate physics. Additional analysis was conducted with the goal of determining the influence of deviation …

Measured Performance Of A High-Efficiency Solar-Assisted Heat Pump Water Heater, Florida Solar Energy Center, Carlos Colon

FSEC Energy Research Center®

This paper describes a novel solar photovoltaic-assisted heat pump water heater (PV-HPWH). The system uses two 310 Wp PV modules, micro-inverters and innovative controls to produce and store daily hot water. The system likely costs half that of solar thermal systems, with greater reliability, no freeze protection and potentially superior performance in cloudy locations. Moreover, no net metering is needed for the PV, which with two modules makes for a simple installation.The HPWH controls have been modified through experimentation such that higher tank temperatures are achieved during the day when solar availability is high while avoiding triggering the compressor during …

Evaluation Of Heat Available From Calcium Chloride Desiccant Hydration Reaction For Domestic Heating In San Francisco, Ca, Michael Giglio

Mechanical Engineering Master's Theses

Thermochemical energy storage has the potential to support the use of solar thermal energy collection in ways that traditional thermal energy storage, like sensible and latent heat storage, have fallen short. Thermochemical energy storage has been shown to have higher storage capacities than sensible and latent storage for dehumidifying applications and does not require insulation like sensible and latent heating do. Sensible heating is focused on maintaining an increased temperature of a storage medium while latent heat storage is focused on maintaining a phase of the storage material. Both sensible and latent heat storage have been shown to have lower …

Sensitivity Analysis For Best-Estimate Thermal Models Of Vertical Dry Cask Storage Systems, Remy R. Devoe, Kevin R. Robb, Steven Skutnik

Faculty Publications and Other Works -- Nuclear Engineering

Loading requirements for dry cask storage of spent nuclear fuel are driven primarily by decay heat capacity limitations, which themselves are determined through recommended limits on peak cladding temperature within the cask. This study examines the relative sensitivity of peak material temperatures within the cask to parameters that influence both the stored fuel residual decay heat as well as heat removal mechanisms. These parameters include the detailed reactor operating history parameters (e.g., soluble boron concentrations and the presence of burnable poisons) as well as factors that influence heat removal, including non-dominant processes (such as conduction from the fuel basket to …

Phased Deep Retrofit Project: Real-Time Measurement Of Energy End-Uses And Retrofit Opportunities, Florida Solar Energy Center, Karen Fenaughty

FSEC Energy Research Center®

This paper describes how utilities can 'make reductions real' through real-time measurement of energy end-uses and corresponding retrofit opportunities. A field evaluation of the methodology was conducted from 2012 to 2016 with Florida Power and Light (FPL), an investor owned utility. A collaborative program between the U.S. Department of Energy (DOE) Building America and FPL led to an ambitious residential energy-efficiency retrofit study aimed to represent FPL's customer base. Fifty-six existing, all electric, occupied Florida homes were instrumented to collect one-minute data on most all energy end-uses in advance of energy-efficiency retrofits. Baseline measurements enabled the development of end-use profiles …

Spectral Phonon Relaxation Time Calculation Tool Based On Molecular Dynamics, Divya Chalise, Tianli Feng, Xiulin Ruan

The Summer Undergraduate Research Fellowship (SURF) Symposium

Thermal conductivity is an important material property which affects the performance of a wide range of devices from thermoelectrics to nanoelectronics. Information about phonon vibration modes and phonon relaxation time gives significant insight into understanding and engineering material’s thermal conductivity. Although different theoretical models have been developed for studying phonon modes and relaxation time, extensive knowledge of lattice dynamics and molecular dynamics is required to compute phonon modal frequencies and relaxation times. Therefore, a computational tool which can take simple inputs to calculate phonon mode frequencies and relaxation time will be beneficial. Through this research work, such computational tool has …

Numerical Simulations Of Transcritical Natural Convection, Ruiwen Wei, Carlo Scalo, Mario Tindaro Migliorino, Kukjin Kim, Jean-Pierre Hickey

The Summer Undergraduate Research Fellowship (SURF) Symposium

In modern engineering applications, system overheating is a key issue that needs to be solved with efficient and reliable cooling technologies. Among the possible mechanisms that these are based on, natural convection cooling is one of the most frequently employed, with applications ranging from cooling of computer micro-components to large nuclear reactors. While many studies have been performed on natural convection employing supercritical or subcritical fluids, little attention has been given to fluids in their transcritical regime. The latter has the potential to yield high performances while avoiding detrimental effects of two-phase systems (e.g. cavitation). In the present study, 2D …

Secondary Atomization: Drop Breakup In A Continuous Air Jet, Grant S. Sondgeroth, Longchao Yao, Catriona M.L. White, Daniel R. Guildenbecher, Jun Chen, Paul E. Sojka

The Summer Undergraduate Research Fellowship (SURF) Symposium

Understanding drop breakup will optimize aircraft engine performance, reduce agro-chemical overspray, and improve pharmaceutical tablet efficacy. Large fuel fragments in engines lead to lowered fuel economy and higher pollutant emissions, while small drops yield more agro-spray drift into surrounding residential and environmental zones. Better pharmaceutical tablets will improve drug uptake and patient comfort.

Engineers and scientists are currently unable to predict the number, size, and velocity of fragments formed during important drop breakup processes. Therefore, we are required to measure these quantities. We use digital inline holography (DIH) to record three-dimensional diameter and position data for fragments formed during multi-mode …

Enhancing The Performance Of A Transportable Environmental Control Unit (Ecu) Operated In High-Temperature Climates, Quan Jun Sun, Ammar M. Bahman, Eckhard A. Groll

The Summer Undergraduate Research Fellowship (SURF) Symposium

Numerous people live or venture into environments, such as the Middle East, where the temperatures can skyrocket as high as 54°C. This leaves many air conditioners unable to operate efficiently. Although much research has been conducted for incorporating vapor injection processes into refrigeration systems, such as ones used in supermarkets, little has been researched regarding the application in extreme heat environments. While most basic air conditioning units do not require the addition of a vapor injection process along with an economizer, this project requires the air conditioning (AC) unit to operate under extreme high temperature conditions. The project investigates the …

Correlating Long-Term Lithium Ion Battery Performance With Solid Electrolyte Interphase (Sei) Layer Properties, Seong Jin An

Doctoral Dissertations

This study was conducted to understand effects of some of key factors (i.e., anode surface properties, formation cycling conditions, and electrolyte conditions) on solid electrolyte interphase (SEI) formation in lithium ion batteries (LIBs) and the battery cycle life. The SEI layer passivates electrode surfaces and prevents electron transfer and electrolyte diffusion through it while allowing lithium ion diffusion, which is essential for stable reversible capacities. It also influences initial capacity loss, self-discharge, cycle life, rate capability and safety. Thus, SEI layer formation and electrochemical stability are primary topics in LIB development. This research involves experiments and discussions on key factors …

Value Of Flow Measurement Accuracy In Hydropower Plants With Short Converging Intakes, Mark Herbert Christian

Doctoral Dissertations

This report documents research undertaken to determine the value of flow measurement accuracy in hydropower plants with short converging intakes. The motivation was to provide a suite of tools and best practices to streamline flow measurement sensor modeling in any type of hydropower plant. The Lower Granite Lock and Dam hydroplant was leveraged in development of the analysis tool. Computational fluid dynamics (CFD) models of Lower Granite Unit 4 provided necessary information about the hydraulic structures distribution through the unit. Two different CFD models were created. The first was done using the as-built plans; the second was created through modifications …

A Spreadsheet Algorithm For Determining The Economic Feasibility Of Micro-Chp Systems In The Arkansas Manufacturing Sector, Ford R. Lewallen

Graduate Theses and Dissertations

Combined heat and power (CHP) systems are not new to the market. However, advances in technology, specifically MicroTurbines, have presented new opportunities for installations of micro-CHP units - defined as 50 kWe to 300 kWe, specifically at small- to medium-sized industrial facilities. One pressing concern is whether or not an industrial plant has a high enough process thermal load requirement to fully utilize the energy output.

This thesis will discuss simulations that were run on several actual electric and thermal load combinations, which correspond to types of manufacturing facilities commonly found in Arkansas. Analysis of the plant usage profiles will …

Piezoelectric Bistable Buckled Beam Energy Harvester., Brian Edward Allgeier

Electronic Theses and Dissertations

A novel energy harvesting device design is presented to be created via microfabrication techniques. Such devices have countless applications for powering low-current electrical devices, especially wireless sensors or transmitters. This micro-electromechanical system (MEMS) design utilizes the piezoelectric response of a bistable buckled beam to gather electrical energy via ambient vibrations. While many traditional piezoelectric energy harvesters (PEH) consist of simple cantilever beam geometries, this nonlinear design utilizes inertial effects of torsional lever arms to actuate a central buckled beam to snap between its two stable states; such an abrupt strain on the piezoelectric beam potentially produces a significantly increased electrical …

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

Graduate 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 …