Mechanical Engineering Commons^™

System Optimization And Material Development Of Solid Oxide Cells For Energy Conversion And Storage, Libin Lei

Theses and Dissertations

Solid oxide cells (SOCs) can convert chemical energy to electricity in the fuel cell mode and store electricity to chemicals in the electrolysis mode. However, there are still critical barriers, such as energy efficiency and durability, for the development and commercialization of SOCs. The objective of this dissertation is to apply system optimization and materials design to address the critical barriers for solid oxide cells in energy conversion and energy storage applications. One major focus of the dissertation is related to improve energy efficiency, enhance the cell performance and achieve multifunctionality in solid oxide electrolysis cells (SOECs). In addition, development …

Characterization Of Evaporation/Condensation During Pool Boiling And Flow Boiling, Mostafa Mobli

Theses and Dissertations

Present dissertation has investigated pool and flow boiling and their characteristics via numerical means. A code was developed to investigate and enhance heat transfer performance during different modes of phase change phenomena. Multiphase heat transfer has proven to be one of the most effective means of heat transfer in different industries, therefore, there have been numerous experimental and numerical studies on the subject of phase change phenomena in a wide range of conditions and setups; yet there are complex bubble dynamics and heat transfer characteristics that remain unresolved. To have a more detailed look at and a better understanding of …

Analysis Of Pellet-Cladding Mechanical Interaction On U3si2 Fuel With A Multi-Layer Sic Cladding Using Bison, Ray A. Freeman

Theses and Dissertations

U3Si2 is currently being considered as a possible replacement for the current light water reactor fuel, UO2. U3Si2’s high melting temperature, high uranium density, and high thermal conductivity are favorable in accident conditions, such as a loss of coolant accident. Improved accident performance is further expected when paired with a SiC/SiC cladding, since it provides relatively high strength and a high oxidation resistance.

Modeling of U3Si2 and SiC/SiC in reactor is currently very important since much of their behavior is still unknown. By implementing models that describe the properties of U3Si2 and SiC/SiC into INL’s fuel performance code BISON, performance …

Physics-Based Approaches For Structural Health Monitoring And Nondestructive Evaluation With Ultrasonic Guided Waves, Md Yeasin Bhuiyan

Theses and Dissertations

The engineering infrastructures have a growing demand for damage monitoring systems to avoid any potential risk of failure. Proper damage monitoring solutions are of a great interest to this growing demand. The structural health monitoring (SHM) and nondestructive evaluation (NDE) offer appropriate online and offline damage monitoring solutions for a variety of mechanical and civil infrastructures that includes unmanned aerial vehicles (UAV), spaceships, commercial aircraft, ground transportation, wind turbines, nuclear spent fuel storage tanks, bridges, naval ships, and submarines. The fundamentals of the ultrasonic SHM and NDE consist of multi-disciplinary fields. The dissertation addresses SHM and NDE using ultrasonic guided …

Effect Of Weak Adhesion Interface On Mechanical And Dielectric Properties Of Composite Materials, Prashant Katiyar

Theses and Dissertations

Interfaces are often the most critical part of the heterogeneous materials and their structures. Such interfaces appear a multiple length scales and significantly affect bulk properties in different material systems. Fiber reinforced composite materials are one such example of heterogeneous materials with interfaces at constituent scale (fiber-matrix interface and interphase) to laminate scale (secondary adhesive joints). Manufacturing induced defects and subsequent in-service damage at these interfaces can severely affect the durability of fiber reinforced laminated composite materials and their joints. In addition to lamination process, defects can also form during secondary joining process (e.g., adhesive bonding and repair) which can …

High Temperature Compression Creep Of U3si2, Emil Angelo Cahanap Mercado

Theses and Dissertations

As a result of the Fukushima Daiichi Nuclear Disaster in 2011, a push for increasing the safety of nuclear power plants was made through research grants funded through the United States Department of Energy via the Accident Tolerant Fuels (ATF) campaign. One of the focuses of the campaign is improving the accident tolerance of nuclear fuel during a loss of coolant accident.

A promising set of being researched from the ATF is Silicon Carbide (SiC) composite cladding and Uranium Silicide (U3Si2) fuel pellets. Under high temperatures, stresses, and times the creep deformation can play an important factor in pellet to …

Combustion Behavior Of Sub-Millimeter Sized Oxygenated And N-Alkane Fuel Droplets, Mohammad Fahd Ebna Alam

Theses and Dissertations

The primary scientific explorations of this thesis work are to better understand (a) microgravity fire-suppression of untested extinguisher, (b) combustion kinetic model refinement of renewable fuel butanol (C4H9OH) isomers, and (c) directly induced cool flame dynamics of higher n-alkane fuels from an isolated small droplet combustion perspective employing computational fluid dynamics with comprehensive chemical kinetics. The chronological development of the research direction shifts from a relatively small fuel like methanol (CH3OH) to heavier straight paraffinic fuel n-decane (n-C10H22). The first installment of the thesis is directed towards answering the feasibility of thennewly considered fire suppressant xenon (Xe) for microgravity space …

Monitoring The Progress Of Damage In A Sicf-Sicm Composite Nuclear Fuel Cladding Under Internal Pressure Using Acoustic Emission, Luis H. Alva

Theses and Dissertations

The relation between the progress of damage and the acoustic emission (AE) activity of a nuclear grade Sif-SiCm composite tubing under internal pressure was studied. The nuclear grade Sif-SiCm composite tubing is manufactured by the company General Atomics (GA) and made of nuclear grade HI Nicalon type S fiber preforms following a chemical vapor infiltration (CVI) technique. Sif-SiCm composites are good candidates to replace current nuclear fuel cladding materials because of the good chemical stability and strength at high temperatures. In this work, a Sif-SiCm composite tubing was tested under internal pressure at room temperature (RT) to study the damage …

Enhance Flow Boiling In Microchannels By Regulating Two-Phase Transport Patterns, Wenming Li

Theses and Dissertations

Flow boiling in microchannels is one of the most promising cooling techniques for microelectronics. Using latent heat by vaporization can significantly improve heat dissipation of high power density electronic devices. Most of the failure of electronic devices is induced by the occurrence of critical heat flux (CHF), which defines the maximum operating conditions. However, the vigorous rapid generation of vapor through phase change leads to chaotic two-phase flows in microchannels, resulting in flowinstability in terms of severe flow, temperature and pressure drop fluctuations. Particularly, the very well-known bubble confinement exacerbates the two-phase flow instabilities and greatly deteriorates heat transfer performance …

Effect Of Material Orientation On The Impact Response Of Graded Cellular Materials, Abigail Wohlford

Theses and Dissertations

In this study, the effect of layer stacking on the energy absorption characteristics of density-graded cellular polymers subjected to high velocity impact is investigated experimentally. The focus in the present work is to characterize the constitutive response and deformation mechanisms of these Functionally Graded Foam Materials (FGFM) using full-field measurements. Uniform foam Quasi-static and dynamic testing of uniform foam specimens are completed for each nominal density used in the layered foam samples. The low strain-rate experiments are performed in order to determine the mechanical properties of foam specimens. The high-rate experiments for homogenous foam specimens were completed to further characterize …

Acousto-Ultrasonic Shm/Nde Methods Toward Field Application, Stephen Harris Howden

Theses and Dissertations

Acousto-ultrasonic nondestructive evaluation (NDE) and structural health monitoring (SHM) methods offers solutions in damage detection, material properties evaluation and more. These ultrasonic waves can propagate through solids and interact with structural features and discontinuities. In this thesis use of several acousto-ultrasonics NDE/SHM methods were explored to evaluate their sensing and detection capabilities toward damage detection field applications in nuclear and aerospace industries.

For nuclear applications, passive sensing using piezoelectric sensors and acoustic emission (AE) techniques were explored on the spent fuel dry storage casks. Dry storage casks are used in the nuclear industry to transport or store spent nuclear fuel …