Heat Transfer, Combustion Commons^™

An Experimental Study Of Formation Of Circulation Patterns In Laminar Unsteady Driven Cavity Flows Using Particle Image Velocimeter (Piv) Techniques, Jon Farkas

LSU New Orleans Theses and Dissertations

Abstract

An experimental study is conducted to determine the velocity fields, from development to steady state, in a square enclosure due to movement of a constant velocity lid using Particle Image Velocitmetry (PIV). Experiments were conducted with water, seeded with hollow glass sphere particles 10 microns in diameter, at three different lid velocities leading to Reynolds numbers in the high laminar to transitional range. Driven Cavity Flow is a classic fluid dynamics case often used for benchmarking of computational codes. Previous work has primarily focused on improving computational codes, experimental work is lacking and focused on obtaining steady state readings. …

Analysis Of Biomass/Coal Co-Gasification For Integrated Gasification Combined Cycle (Igcc) Systems With Carbon Capture, Henry A. Long Iii

LSU New Orleans Theses and Dissertations

In recent years, Integrated Gasification Combined Cycle Technology (IGCC) has become more common in clean coal power operations with carbon capture and sequestration (CCS). Great efforts have been spent on investigating ways to improve the efficiency, reduce costs, and further reduce greenhouse gas emissions. This study focuses on investigating two approaches to achieve these goals. First, replace the subcritical Rankine steam cycle with a supercritical steam cycle. Second, add different amounts of biomass as feedstock to reduce emissions. Finally, implement several types of CCS, including sweet- and sour-shift pre-combustion and post-combustion.

Using the software, Thermoflow®, this study shows that utilizing …

Anisotropic Thermal Property Measurement Of Carbon-Fiber/Epoxy Composite Materials, Tian Tian

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

This work originated from a need for understanding heat transfer in carbon-fiber/epoxy natural-gas tanks undergoing rapid heating during refilling. The dissertation is focused on the determination of the anisotropic thermal properties of carbon-fiber/epoxy composite materials for in-plane and through-thickness directions. An effective anisotropic parameter estimation system consisting of the 3ω experimental technique and an anisotropic two-dimensional heat transfer model is developed.

In the present work, the 3ω method, an experimental technique that has been well established to evaluate the thermal properties of isotropic materials, especially thin film materials, is extended to treat the thermal properties of bulk anisotropic …

Engine Simulation And Diagnostic Test Bed: Final Design Report, Jeff Lewis, Cody Scott, Todd Smith

Mechanical Engineering

The San Luis Obispo High School Automotive Technology Shop has a 1991 Buick V-6 Engine which uses the OBD-I (On-Board Diagnostics, generation one) standard for diagnostic testing and troubleshooting. In order to expand the capabilities of the Automotive Technology program and allow students to gain first-hand experience troubleshooting older OBD-I engines, the shop has a need for this engine to become part of a diagnostic and troubleshooting test bed. Some of the diagnostic tests the students will perform include checking cylinder pressure, monitoring coolant system temperatures, interpreting error codes from the OBD-I system, and conducting enhanced smog testing. All of …

Floating Tube Heat Exchangers, Patrick Harris, Christina Gedeon, Leonel Medrano, George Milam

Mechanical Engineering

With the slowly diminishing supply of fossil fuels across the world and the heightened risk of carbon dioxide pollution leading to global warming, a shift towards renewable energy is gaining momentum. Recent advances in wind and solar power technology have increased the power density of alternative sources while decreasing the cost per kilowatt-hour, but the technology has not become advanced enough yet for large scale deployment. Combined Power Cooperative has developed a revolutionary design for a concentrated solar power plant that utilizes Fresnel reflectors and a large body of water in which to install them. In addition to being low-cost, …

Development Of Spray Cooling For High Heat Flux Electronics, Jeremy Scott Junghans

Graduate Theses and Dissertations

The thermal demands of modern day electronic systems require innovative thermal solutions. Spray cooling has proven to be able to cool heat fluxes orders of magnitude higher than traditional cooling methodologies. This work includes a comparison of spray cooling to standard thermal management methodologies. Key system parameters and considerations are discussed. The properties of available packaging materials and their effect on the reliability of a spray cooled system are presented. Parameters such as fluid temperature, droplet size, fluid velocity and flow rate all directly impact performance and are detailed in this work. Finally, results from of a wide range of …

Rational Efficiency Of A Heat Exchanger, Jim Mcgovern, Brian P. Smyth

Articles

The authors propose a new and unique definition for the rational efficiency of a heat exchanger. This new rational efficiency is defined in terms of its sub-rational efficiencies: a heat transfer rational efficiency and a friction rational efficiency for each of the fluid systems comprising the heat exchanger. The heat transfer rational efficiency is based on the definition of a mean temperature for the heat source and a mean temperature for the heat sink and reflects the exergy supplied and the exergy received, due to heat transfer only. The friction rational efficiency for each fluid system of the heat exchanger …

Development Of Analytic Tools For Computational Flame Diagnostics, Mehrnaz Rouhi Youssefi

Master's Theses

No abstract provided.

An Optical Analysis Of The Blowoff Behavior For Bluff Body-Stabilized Flames In Vitiated Flow, Trevor Jensen

Master's Theses

In bluff body-stabilized flames, a variety of physical phenomena contribute to the flame destabilization as lean blowoff is approached. These effects include increased strain on the flame shear layers, decreased attenuation of Bénard-von Kármán vortex shedding, and the presence of thermoacoustic instabilities. Lean, bluff body-stabilized flames were studied in an enclosed rectangular-duct, turbulent combustion rig with a triangular flame holder under vitiated conditions with both symmetric and asymmetric fuel distributions. Air and fuel flows within the rig were characterized using a PIV system and a continuous emissions gas analyzer, respectively.

High-speed videos of these flames undergoing blowoff were taken to …

Experimental And Numerical Investigations Of Tubular-Shaped Direct Methanol Fuel Cells (Dmfcs), Travis R. Ward

Master's Theses

This study focuses on both the numerical and experimental investigations of the novel, passively operated, tubular-shaped, Direct Methanol Fuel Cell (DMFC) as an alternative geometry to the traditional planar-shaped fuel cell. The benefit of the tubular geometry compared to the planar geometry is the higher instantaneous volumetric power density provided by the larger active area, which could be beneficial in applications that require a high instantaneous power while occupying a small volume. First, a two-dimensional, two-phase, non-isothermal model was developed to investigate the steady-state performance and design characteristics of a tubular-shaped, passive DMFC. It was found that a higher ambient …

Characteristics Of The Hydrogen Electrode In High Temperature Steam Electrolysis Process, Chao Jin, Chenghao Yang, Fanglin Chen

Faculty Publications

YSZ-electrolyte supported solid oxide electrolyzer cells (SOECs) using LSM-YSZ oxygen electrode but with three types of hydrogen electrode, Ni–SDC, Ni–YSZ and LSCM–YSZ have been fabricated and characterized under different steam contents in the feeding gas at 850°C. Electrochemical impedance spectra results show that cell resistances increase with the increase in steam concentrations under both open circuit voltage and electrolysis conditions, suggesting that electrolysis reaction becomes more difficult in high steam content. Pt reference electrode was applied to evaluate the contributions of the hydrogen electrode and oxygen electrode in the electrolysis process. Electrochemical impedance spectra and over potential of both electrodes …

Time-Dependent Crack Growth Behavior Of Alloy 617 And Alloy 230 At Elevated Temperatures, Shawoon Kumar Roy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Two Ni-base solid-solution-strengthened superalloys: INCONEL 617 and HAYNES 230 were studied to check sustained loading crack growth (SLCG) behavior at elevated temperatures appropriate for Next Generation Nuclear Plant (NGNP) applictaions with constant stress intensity factor (K _max = 27.75 MPa[checkmark]m) in air. The results indicate a time-dependent rate controlling process which can be characterized by a linear elastic fracture mechanics (LEFM) parameter - stress intensity factor (K). At elevated temperatures, the crack growth mechanism was best described using a damage zone concept. Based on results and study, SAGBOE (stress accelerated grain boundary oxidation embrittlement) is considered the primary reason for …

Immersion Cooling Of Photovoltaic Cells In Highly Concentrated Solar Beams, Ahmed Darwish

UNLV Theses, Dissertations, Professional Papers, and Capstones

Concentrated solar radiation can be utilized to generate electrical power from photovoltaic cells, but concentrated solar radiation increases the photovoltaic cell’s temperature. This increase in temperature can lead to degradation of the cell efficiency, and too high of a temperature can damage the cell’s integrity. This is particularly important in dish and tower systems where a maximum uniform flux may be difficult to achieve. While a variety of approaches have been used to the keep the cells cool, most are based upon removal of heat from the back (opposite surface of the incident flux exposed surface) of the cell. This …

The Transfer Of Laser-Machined Micro-Structured Patterns From Silicon To Polymethyl Methacrylate, Warren E. Withrow

Mechanical & Aerospace Engineering Theses & Dissertations

This research project's purpose was transferring a micro-scaled pattern from a silicon wafer to a polymethyl methacrylate (PMMA), or acrylic, substrate through light absorption generated heat. The secondary objective was to determine if the pattern on the silicon wafer could then be transferred to silica (i.e. a microscope glass slide) through light absorption generated heat. Once this pattern-transfer technique is developed for the micro scale, it could be instituted on the nano scale. The experiment was designed to find an alternate method to that currently being used to mass-produce compact discs (CDs). The most popular method employs a stamping process …

Thrust-Vector Control, Dane Larkin, Harsimran Singh

Mechanical Engineering

Mission Statement

The purpose of this project is to design, build, and test a thrust-vectoring rocket nozzle which will aid in controlling the trajectory of a solid-booster rocket. The system prototype must meet the requirements set forth by the sponsoring enterprise.

The Enterprise

Stellar Exploration is a small space systems technology company located in San Luis Obispo, CA. Stellar Exploration is currently seeking a thrust-vectoring system for its Silver Sword rocket.

Project Scope

The design and analysis portion of this project accounted for a system that would be mounted on to a rocket for operational flight. Therefore, this team has …

Rayleigh Test Apparatus Design Report, Josef Duller, Owen Raybould, James Nicovich

Mechanical Engineering

The Rayleigh Test Apparatus is a device that will be used to test the thermodynamic properties of Nitrous Oxide to assess the feasibility of using this fluid as a coolant for a hybrid rocket aero spike. The aero spike is intended to redirect the propulsion flow as it leaves the engine to create a more efficient flow pattern at low and high altitudes. However, there are issues of overheating which leads to melting of the aero spike. For this reason, the use of nitrous oxide (N2O) as a coolant is being explored. N20 is being considered because it is already …

Analyse Du Comportement Réel Et De L'Optimisation Structurelle Des Cycles De Turbines À Gaz, Alexandru Dobrovicescu, Michel Feidt, Lavinia Grosu, Jim Mcgovern, Georgiana Tirca-Dragomirescu

Conference Papers

L’article présente une étude comparative, basée sur l’analyse exégétique, de l’effet de non prise en considération du comportement réel de l’agent thermique et de l’utilisation des modèles simplifiés pour calculer les performances des cycles de turbines à gaz avec et sans récupération de chaleur. Un intérêt spécial a été réservé au processus de combustion et au transfert de chaleur dans le préchauffeur d’air. La variation des destructions et des pertes d’exergie par rapport à la variation des paramètres fonctionnels est présentée.

Heat Transfer Through A Rotating Ball Bearing At Low Angular Velocities, Sarah Isert

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Bearings are commonly used in mechanical systems when there are rotating parts in the system. For bearings that run at speeds above about 1000 revolutions per minute, such as those used in aircraft turbines, machining tools, and automotive engines, it is important to take into account the heat transfer through the bearing system due to friction. Heat transfer is generally not considered for applications where the bearing is rotating at low speeds, such as clocks and bicycles. However, for certain aerospace applications, such as precision instruments or wind turbines, the heat transfer through the bearing becomes relevant. The case where …