Mechanical Engineering Commons^™

Thermal Vacuum Integration For Cal Poly's Space Environments Laboratory, Chelsea Barackman, Steven Jackowski

Aerospace Engineering

The purpose of the senior project is to construct a thermal vacuum by utilizing a preexisting vacuum chamber in the Space Environments Lab, and a donated Advanced Thermal Sciences (ATS) chiller. While a thermal vacuum is already available on campus, building one for the Space Environments Lab would grant undergraduates access to the equipment, allowing a much better understanding of testing methods and procedures in use by the aerospace industry. This paper explains the design and analysis of the thermal vacuum (T-VAC) project as well as the operation and procedures required for the ATS chiller and fill/drain tank. The thermal …

California Olive Ranch Hedger, Tyler Enos, Seth Abbott, David Gamba

Mechanical Engineering

The purpose of this project is to evaluate the problems of the current KCI (Kingsburg Cultivator Incorporated) olive tree hedger in use at California Olive Ranch (COR) in Artois, CA, and then correct these problems which should yield a better performing, more efficient, and reliable machine. These problems include: the hydraulic oil temperature getting too high, the saw blades not having enough horsepower, and poor cutting performance due to operator error as well as terrain variations.

Cryogenic Heat Switch, Daniel Brodkey, Esteban Ruiz, Cristal Vasquez

Mechanical Engineering

A prototype cryogenic heat switch capable of transferring heat at cryogenic temperatures, while decoupling to prevent irreversible heat damage and minimizing parasitic heat loads, is to be developed for the Jet Propulsion Laboratory. Various material properties and cryogenic heat transfer processes will be investigated to determine the best solution for this project. A working proof of concept model will be constructed that may eventually be integrated onto a spacecraft’s passive cooler systems to protect them from the irradiation emitted by the sun, from the albedo of planets, and other malicious heat sources.

Frg Turbojet, Tyler Vitti

Computer Engineering

Members of the Cal Poly SLO campus club FRG work together with students of several different disciplines to build a functional turbojet engine. Engineering approaches include design, fabrication, testing, and computer sensing, control, and integration. The goal of the project is to produce a running turbojet engine monitored and controlled by embedded hardware and specialized PC software. This project is to be used by later groups for further research and development.

An Investigation Of Mist/Air Film Cooling With Application To Gas Turbine Airfoils, Lei Zhao

LSU New Orleans Theses and Dissertations

Film cooling is a cooling technique widely used in high-performance gas turbines

to protect turbine airfoils from being damaged by hot flue gases. Film injection holes are

placed in the body of the airfoil to allow coolant to pass from the internal cavity to the

external surface. The ejection of coolant gas results in a layer or “film” of coolant gas

flowing along the external surface of the airfoil.

In this study, a new cooling scheme, mist/air film cooling is proposed and

investigated through experiments. Small amount of tiny water droplets with an average

diameter about 7 μm (mist) is …

Analysis And Testing Of Heat Transfer Through Honeycomb Panels, Daniel D. Nguyen

Aerospace Engineering

This project attempts to simulate accurately the thermal conductivity of honeycomb panels in the normal direction. Due to the large empty space of the honeycomb core, the thermal radiation mode of heat transfer was modeled along with conduction. Using Newton’s Method to solve for a steady state model of heat moving through the honeycomb panel, the theoretical effective thermal conduction of the honeycomb panel was found, ranging from 1.03 to 1.07 Q/m/K for a heat input of 2.5 W to 11.8 W. An experimental model was designed to test the theoretical results, using a cold plate and a heat plate …

Perceptions Measurement Of Professional Certifications To Augment Buffalo State College Baccalaureate Technology Programs, As A Representative American Postsecondary Educational Institution, Christopher N. Brown

Industrial Technology Theses

The purpose of this study was to assess, measure, and analyze whether voluntary, nationally-recognized professional certification credentials were important to augment technology programs at Buffalo State College (BSC), as a representative postsecondary baccalaureate degree-granting institution offering technology curricula. Six BSC undergraduate technology programs were evaluated within the scope of this study: 1.) Computer Information Systems; 2.) Electrical Engineering, Electronics; 3.) Electrical Engineering, Smart Grid; 4.) Industrial Technology; 5.) Mechanical Engineering; and 6.) Technology Education. This study considered the following three aspects of the problem: a.) postsecondary technology program enrollment and graduation trends; b.) the value/awareness of professional certifications to employers …

Numerical Modeling Of High Temperature Bayonet Heat Exchanger And Decomposer For Decomposition Of Sulfur Trioxide, Vijaisri Nagarajan, Yitung Chen, Tzu-Chen Hung, Qiuwang Wang, Valery Ponyavin

College of Engineering: Graduate Celebration Programs

Motivation

• Hydrogen is an attractive energy carrier in the future energy technology.

• Hydrogen is produced from splitting of water through various process namely electrolysis, photo-electrolysis, photo-biological production and thermochemical water-splitting.

• The aim of this study is to numerically investigate fluid flow, heat transfer and chemical reaction in bayonet high temperature heat exchanger and decomposer.

• Parametric studies are performed to achieve maximum decomposition with less pressure drop.

Latent Heat Thermal Energy Storage With Embedded Heat Pipes For Concentrating Solar Power Applications, Christopher Robak

Master's Theses

An innovative, novel concept of combining heat pipes with latent heat thermal energy storage (LHTES) for concentrating solar power (CSP) applications is explored. The low thermal conductivity of phase change materials (PCMs) used in LHTES presents a design challenge due to slow heat transfer rates during heating and cooling of the material. Heat pipes act to decrease the thermal resistance in the PCM, increasing the overall heat transfer rate sufficiently for use in CSP. First, a laboratory scale experiment is presented to validate the concept of using heat pipes in LHTES to reduce thermal resistance in PCM. A commercial scale …

Computational Models Of Sub-Divided Thermal Energy Storage Tanks Used In Concentrating Solar Power Plants With Parabolic Trough Collectors, Jesus D. Ortega ^, Vinod Kumar *

COURI Symposium Abstracts, Spring 2012

No abstract provided.

Numerical Study Of The Performance Of A Model Scramjet Engine, Ayad Alhumadi

Mechanical & Aerospace Engineering Theses & Dissertations

A computational parametric investigation was conducted to study the effect of variations to several geometric parameters on the performance of a two-dimensional model scramjet engine (square cross section area for 3-D model). Geometric parameters included backstep location, height, and angle and fuel injector angle, diameter, and location. Two- and three-dimensional geometries have been studied, using a finite-volume computational fluid dynamics (CFD) code (FLUENT) with structured grids with sizes between 50,000 and 90,000 cells for the two-dimensional geometry and with structured hexahedral grid sizes between 650,000 and 949,725 cells for the three-dimensional geometry. Otherwise, identical values of program inputs were utilized …

Characterization Of Centrifugally-Loaded Flame Migration For Ultra-Compact Combustors, Kenneth D. Lebay

Theses and Dissertations

The Air Force Research Laboratory (AFRL) has designed an Ultra Compact Combustor (UCC) showing viable merit for significantly reducing gas turbine combustor length making it a viable candidate for implementation as an inter-turbine burner and realization of efficiency benefits from the resulting near constant temperature cycle. This concept uses an off-axis combustor cavity and projects approximately 66% length reduction over a conventional combustor. The annular nature of the cavity creates high angular acceleration levels, on the order of 500-3500 g's, resulting in strong centrifugal and buoyant forces. This unique combination works to significantly reduce the required burn time and subsequently …

Combustion Simulations Using Graphic Processing Units, Mingjie Wang

Master's Theses

Graphic processing units (GPUs) are powerful graphics engines featuring high levels of parallelism and extreme memory bandwidth, which constitute a powerful computing platform to solve complex problems involving chemically reacting flows. In the present study, computer programs for combustion simulations with detailed chemical kinetic mechanisms were compiled in the Compute Unified Device Architecture (CUDA) language for NVIDIA GPU architecture. Ignition processes were simulated under constant pressure and constant volume conditions using an explicit 4^th order Runge-Kutta algorithm for time integration. Sufficiently small time steps were identified with time scale analysis to ensure the integration stability. The program was validated …

Non-Isothermal Cool Flames In Unstirred Static Reactors: A Compressible Model With Global Kinetics, Michael R. Foster, Howard Pearlman

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

A compressible model is developed with kinetics based on the Wang–Mou five-step global kinetic scheme and used to evaluate the temperature, concentration, and velocity fields characteristic of low temperature combustion in unstirred static reactors. This work relaxes the assumption of small exothermicity that enabled prior studies to employ the Boussinesq approximation, valid for cases where BT << 1, i.e., slow reactions and cool flames. In this study, the range of validity of the model is extended to cases with large temperature excursions, including multi-stage ignition. For the weakly exothermic cases considered, including modes of slow reaction and cool flames, the Boussinesq approximation is completely adequate. However, it overpredicts the density change and underpredicts the ignition delay time for high-temperature ignitions. Qualitative comparison with experimental results acquired at microgravity conditions are also discussed.

Numerical Simulation Of Natural Convection In Rectangular Enclosures Of Varying Aspect Ratios And Its Feasibility In Environmental Impact Management Studies, Charles R. Walker

College of Graduate Studies: Theses & 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 …

An Investigation On Cocombustion Behaviors Of Hydrothermally Treated Municipal Solid Waste With Coal Using A Drop-Tube Reactor, Liang Lu, Yuqi Jin, Masato R. Nakamura, Marco J. Castaldi, Kunio Yoshikawa

Publications and Research

This work aims at demonstrating the feasibility of replacing Indonesian coal (INC) with hydrothermally treated municipal solid waste (MSWH) in cocombustion with high ash Indian coal (IC). The combustion efficiencies and emissions (CO, NO) of MSWH, INC and their blends with IC for a series of tests performed under a range of temperatures and air conditions were tested in a drop- tube reactor (DTR). The results showed the following. The combustion efficiency of IC was increased by blending both MSWH and INC and CO emission was reduced with increasing temperature. For NO emission, the blending of MSWH led to the …

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 …