Engineering Commons^™

Wind And Thermal Effects On Ground Mounted Photovoltaic (Pv) Panels, Chowdhury Mohammad Jubayer

Electronic Thesis and Dissertation Repository

A combination of Computational Fluid Dynamics (CFD) simulations and wind tunnel experiments are carried out to investigate the effects of wind on the aerodynamic loading and heat transfer of a ground mounted stand-alone photovoltaic (PV) panel with tilt angle of 25^o in open country atmospheric boundary layer. Several azimuthal wind directions are considered: Southern 0^o, Southwest 45^o, Northwest 135^o and Northern 180^o. Three dimensional Reynolds-Averaged Navier-Stokes (RANS) approaches with an unsteady solver using Shear Stress Transport (SST) k-ω turbulence closure are employed for the CFD simulations, whereas Particle Image Velocimetry (PIV) and …

Mhttu Implementation Final Project Report, Angelica Ramirez, Julian Samayoa, Matt Keeble

Mechanical Engineering

Lawrence Livermore National Laboratory has invested considerable effort in developing fireproof high-efficiency particulate air (HEPA) filters. Due to the nature of LLNL’s research, the air leaving its lab facilities must be filtered before it is released into the atmosphere; thus, each laboratory is equipped with large banks of HEPA filters through which all internal air is exhausted. Over the years, however, fires have erupted in the labs and entire banks of HEPA filters have been destroyed, resulting in repairs and crucial downtime that prove costly.

Engineers and scientists alike have been seeking a permanent solution to this problem, and one …

Temperature Controlled Packaging Container For Biologics And Pharmaceuticals, Melinda Phan, Yufay Chow-Yee, Abraham Ho

Mechanical Engineering

Clinical Supplies Management, Inc. (CSM) provides clinical trial services to biotechnology and pharmaceutical companies by shipping pharmaceuticals to clinics and other patients. In winter 2014, CSM presented a temperature control packaging project to the Cal Poly Senior Project class. As a result, three Cal Poly Mechanical Engineering Students were tasked to design, manufacture, and qualify a shipping container that would maintain ten 10 mL vials between 2-8°C for 96 hours. The final product would have to cost less to ship than the Credo Cube, CSM’s current temperature control packaging product. After considerable research and analysis on possible temperature control technologies, …

Lightweight, High-Temperature Radiator For In-Space Nuclear-Electric Power And Propulsion, Briana N. Tomboulian

Doctoral Dissertations

The desire to explore deep space destinations with high-power and high-speed spacecraft inspired this work. Nuclear Electric Propulsion (NEP), shown to provide orders of magnitude higher specific impulse and propulsion efficiency over traditional chemical rockets, has been identified as an enabling technology for this goal. One of large obstacle to launching an NEP vehicle is total mass. Increasing the specific power (kW/kg) of the heat radiator component is necessary to meet NASA’s mass targets. This work evaluated a novel lightweight, high-temperature carbon fiber radiator designed to meet the mass requirements of future NEP missions. The research is grouped into three …

Inverse Volume-Of-Fluid Meshless Method For Efficient Non-Destructive Thermographic Evaluation, Hussein Awad Kurdi Saad

Doctoral Dissertations and Master's Theses

A novel computational tool based in the Localized Radial-basis Function (RBF) Collocation (LRC) Meshless method coupled with a Volume-of-Fluid (VoF) scheme capable of accurately and efficiently solving transient multi-dimensional heat conduction problems in composite and heterogeneous media is formulated and implemented. While the LRC Meshless method lends its inherent advantages of spectral convergence and ease of automation, the VoF scheme allows to effectively and efficiently simulate the location, size, and shape of cavities, voids, inclusions, defects, or de-attachments in the conducting media without the need to regenerate point distributions, boundaries, or interpolation matrices. To this end, the Inverse Geometric problem …

Single-Phase Turbulent Enthalpy Transport, Bradley J. Shields

Masters Theses

Vapor generation is central to the flow dynamics within fuel injector nozzles. Because the degree of atomization affects engine emissions and spray characteristics, quantification of phase change within diesel fuel injectors is a topic of design interest. Within the nozzle, the large pressure gradient between the upstream and downstream plena induce large velocities, creating separation and further pressure drop at the inlet corner. When local pressure in the throat drops below the fluid vapor pressure, phase change can occur with sufficient time. At the elevated temperatures present in diesel engines, this process can be dependent upon the degree of superheat, …

Unsteady Flamelet Progress Variable Modeling Of Reacting Diesel Jets, Muhsin Mohammed Ameen

Open Access Dissertations

Accurate modeling of turbulence/chemistry interactions in turbulent reacting diesel jets is critical to the development of predictive computational tools for diesel engines. The models should be able to predict the transient physical and chemical processes in the jets such as ignition and flame lift-off. In the first part of this work, an existing unsteady flamelet progress variable (UFPV) model is employed in Reynolds-averaged Navier-Stokes (RANS) simulations and large-eddy simulations (LES) to assess its accuracy. The RANS simulations predict that ignition occurs toward the leading tip of the jet, followed by ignition front propagation toward the stoichiometric surface, and flame propagation …

Thermal Convection Of Non-Fourier Fluids, Rahim Mohammadhasani Khorasany

Electronic Thesis and Dissertation Repository

The natural convection of non-Fourier fluids of the dual-phase-lagging (DPL) type is examined. These fluids possess a relaxation time and a retardation time, reflecting the delay in the response of the heat flux and the temperature gradient with respect to one another. DPL fluids span a wide range of applications, including low-temperature liquids, fluids subjected to fast heat transfer processes, and nanofluids (NFs), for which both the relaxation and retardation times are expressed in terms of nanoparticle concentration and solution properties. Both stationary and oscillatory convection become equally probable as the relaxation time increases. A nonlinear spectral approach is also …

Measurement And Verification - Retro-Commissioning Of A Leed Gold Rated Building Through Means Of An Energy Model: Are Aggressive Energy Simulation Models Reliable?, Justin M. Marmaras

Masters Theses

During the construction of the new 3 story, 25,000+ square foot police station, a decision was made to participate in the LEED program to ensure the building had low operating costs, reduced emissions, conserved water and overall energy. The design of the building includes a primary-secondary ground source heat pump (GSHP) loop, a Dedicated Outside Air System (DOAS) with Energy Recovery Ventilation (ERV) wheel, all controlled by CO2 monitoring through Demand Control Ventilation (DCV) to supply heat pumps located in each space; all monitored by a Building Automation System (BAS).

The building’s future energy performance was predicted through an energy …

Numerical Analysis Of Two Phase Flow And Heat Transfer In Condensers, Pooya Mirzabeygi

Electronic Thesis and Dissertation Repository

Steam surface condensers are commonly used in the power generation industry and their performance significantly affects the efficiency of the power plant. Therefore, it is vital to acquire a better understanding of the complex phenomena occurring inside condensers. A general three-dimensional numerical model is developed in this study to simulate the two-phase flow and heat transfer inside full-scale industrial condensers with irregular tube bundle shapes. The Eulerian-Eulerian two-phase model is selected to simulate gas and liquid flows and the interaction between them. A porous media approach is adopted to model the presence of large number of tubes in the condenser. …

Design And Fabrication Of A Low-Cost Turbine Engine Component Testbed (Tect), Joshua A. Hartman

Masters Theses

With gas turbine engine testing becoming very expensive because of the increasing complexity involved with the engine, engine subsystems, and test support systems, a low-cost Turbine Engine Component Testbed (TECT) is proposed. This engine build is given the designation J1-H-02. In the present study, a small augmented gas turbine engine (GTE) is constructed. The TECT engine is built with modularity as a key design consideration to allow for flame-tube patterns and augmentor sections to be changed quickly for combustion experiments that have gained impetus due to combustion anomalies/instabilities inherent with future military engine augmentors. This testbed allows for an effective …

A Cfd Assisted Control System Design For Supercritical Water Cooled Reactor, Rohit V. Maitri

Electronic Thesis and Dissertation Repository

In this study, the methodology to construct a control system based on computational fluid dynamics (CFD) simulations is developed for supercritical water cooled reactor (SCWR). The CFD model using Reynolds Stress Model (RSM) and k-w SST model is validated with the experimental cases of steady state and vertically up flowing supercritical water in circular tubes for normal heat transfer and deteriorated heat transfer (DHT) cases. This model is extended to simulate the transient thermal-hydraulic behaviour of supercritical fluid flow and heat transfer, and the results are also compared with the 1-D numerical model, THRUST. The DHT phenomenon is investigated using …

Minimization Of The Effects Of Secondary Reactions On Turbine Film Cooling In A Fuel Rich Environment, Andrew T. Shewhart

Theses and Dissertations

The demand for increased thrust, higher engine efficiency, and reduced fuel consumption has increased the turbine inlet temperature and pressure in modern gas turbine engines. The outcome of these higher temperatures and pressures is the potential for unconsumed radical species to enter the turbine. Because modern cooling schemes for turbine blades involve injecting cool, oxygen rich air adjacent to the surface, the potential for reaction with radicals in the mainstream flow and augmented heat transfer to the blade arises. This study evaluated various configurations of multiple cylindrical rows of cooling holes in terms of both heat release and effective downstream …

Formula Sae Cooling System Design, Lisa Van Den Berg, Brandon Lofaro

Mechanical Engineering

The overall objective of this senior project is to develop, via testing and analysis, a guided process that will aid the Cal Poly Formula SAE team in designing their cooling system. More specifically, a set of designed tests will yield the results necessary in determining a combination of fan and radiator that will achieve appropriate cooling.

A test section that has the capability of interfacing with both the wind tunnel in the Thermal Science Lab and a radiator will be used to facilitate the necessary experiments. The wind tunnel is powered by fan controlled by a variable frequency drive that …

Design And Construction Of A Chemical Engineering (Cheme) Car Using Thermoelectrics, Timothy Barnhill, Sara Davino, Spencer Faltin, Lauryn Jamison, Christina Papadimitrio, Mccall Rogers

Senior Theses

Six chemical engineering undergraduates at the University of South Carolina formed a team to compete in the 2014 AIChE Chem-E-Car competition at the Southern Regional Student Conference in San Juan, Puerto Rico, in March. In the Chem-E-Car competition, students must design and build a vehicle powered by an unconventional form of chemical energy to carry a specified weight over a given distance (1). The group used knowledge gained through undergraduate study to construct a small-scale vehicle that is powered by a set of thermoelectric generators utilizing a heat gradient between boiling water and an ethanol-dry ice mixture (2). An iodine …

Transport Resistance In Polymer Electrolyte Fuel Cells, Jon Patrick Owejan

Doctoral Dissertations

Fuel cells offer the potential for high efficiency energy conversion with only water and heat as significant products of the electrochemical reaction. For a cost-competitive product, fuel cell researchers are exploring the limits of the Pt catalyst loading in parallel with performance and durability trade-offs. A significant portion of the performance loss in low-cost PEMFCs is associated with the partial pressure of oxygen (for an air cathode) at the Pt surface. This dissertation explores the main components of oxygen transport resistance which are associated with diffusion through partially saturated porous media and the ionomer coating in the catalyst layer.

Under …

Investigation Of Boiling Performance Of Graphene-Coated Surfaces, Daniel C. Stack

Honors Capstone Projects - All

In this Capstone Project, I sought to investigate the boiling performance of graphene-coated surfaces. Boiling was accomplished in a pool boiling chamber, with samples of graphene-coating SiO₂ wafers. I developed a procedure for graphene transfer for sample fabrication. Samples were prepared with graphene grown on copper substrates by chemical vapor deposition (CVD). Graphene was transferred from copper substrates to SiO­₂ wafers by a thermal release transfer tape. Copper was etched away from the tape-graphene combination by ferric chloride, and the tape was peeled away after heating, leaving graphene on the SiO₂ substrate. Contact angles were measured to …

High Temperature Ltcc Based Sic Double-Sided Cooling Power Electronic Module, Hao Zhang

Graduate Theses and Dissertations

This objective of this dissertation research is to investigate a module packaging technology for high temperature double-sided cooling power electronic module application. A high-temperature wire-bondless low-temperature co-fired ceramic (LTCC) based double-sided cooling power electronic module was designed, simulated and fabricated. In this module, the conventional copper base plate is removed to reduce the thermal resistance between the device junctions to the heat sink and to improve the reliability of the module by eliminating the large area solder joint between the power substrate and the copper base plate. A low-temperature co-fired ceramic (LTCC) substrate with cavities and vias is used as …

Design And Economic Analysis Of A Geothermal Vertical Coupled Heat Pump System For The University Of Tennessee, Knoxville Campus, Joseph W. Birchfield Iv, Will Kester, Jason Cho

Chancellor’s Honors Program Projects

No abstract provided.

Neutron Imaging Of Lithium (Li) Coolants Inside High Temperature Niobium (Nb) Heat Pipes, Brad Harrison Hight

Masters Theses

Lithium (Li) behavior inside a high temperature Nb-Li leading edge heat pipe was successfully imaged under induction heating operation via neutron imaging. Startup and cool-down operations gave visual confirmation of bulk Li movement using both gravity assisted and inverted operating orientations. The pipe was imaged during an operation cycle from ambient conditions, heated to a steady state temperature of 908.8 ⁰C, and allowed to cool below 200^°C. The experiment was performed at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland, and at the Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee.

Tomographic images …

Thermal Response Characterization And Low Fluid Velocity Measurements Using Specialized In-Situ Thermocouples Via The Loop Current Step Response Method, Alexander Hashem Hashemian

Masters Theses

In this study, a specialized balanced-leads thermocouple was developed to perform in-situ thermal response characterization via the LCSR test method. Thermal response characterization of installed thermocouples is essential in order to obtain accurate positional temperature data in rapid transient applications. An analytical model is presented that fully describes the thermocouple system based on a first-principles approach to the heat transfer physics of the sensor. In conjunction with the LCSR test, the full model presented yields quantifiable characterization parameters useful for determining accurate positional temperature data. It is necessary to employ a balanced-leads thermocouple for this experimental procedure in order to …

Formulation And Experimental Verification Of Alternate Calibration Techniques Of The Temperature Dependent Response Of Phosphor Fluorescence, Kelsey Michele Winstead

Masters Theses

The overall goal of this work is to provide an alternative approach to the thermographic phosphor (TP) time constant calibration method for temperature recovery. In this work two techniques are proposed that retain the pulsed source input used in the standard TP time constant calibration approach but reinterpret the phosphor response taken a fixed distance such that the single-exponential decay assumption is removed. The methods do not require knowledge of key parameters prior to data processing, nor do they involve complicated numerical schemes that attempt to fit data in the low signal-to-noise region of the phosphor response. The approaches do …

Simulation Of An Intake Manifold Pre-Heater For Cold Diesel Engine Startup, Patrick K. Kreun

Masters Theses

Ensuring consistent, reliable diesel engine startups in cold temperatures is of utmost importance in a number of applications. Under extreme temperatures, the use of glow plugs is complemented by intake manifold heaters. In these, the energy released from combustion increases the intake air temperature before the air enters the main combustion chamber. Since the process also alters the stoichiometry of the fuel-air mixture at the intake ports, the preheater operation must be optimized in order to guarantee successful and reliable in-cylinder combustion during engine startups. This paper describes the development of an intake manifold model incorporating an air pre-heater for …

Analytical Performance Evaluation Of Thermoelectric Modules Using Effective Material Properties, Sean Lwe Leslie Weera

Masters Theses

Designers often face the predicament of non-standardized forms of performance data provided by thermoelectric module manufacturers. Other than experimental means the only method to evaluate the performance of a product would be through analytical modeling using material properties that are usually undisclosed and unknown. This work studies the theoretical approach of obtaining such material properties using the maximum operating parameters reported by the manufacturers. These values are then analytically employed to evaluate the performances of these thermoelectric modules. Experimental means are also devised and carried out on these test samples to validate the integrity of the results. Three-way comparisons between …

Operational Characteristics Of An Ultra Compact Combustor, Christopher J. Damele

Theses and Dissertations

Ultra Compact Combustors offer unique solutions to minimize engine size and weight. They accomplish this by reducing the number of components in the engine core and perform the combustion in a circumferential cavity that encircles the core flow. Within this cavity, the fuel is injected rich. Burning continues to occur in the vane passage beneath the circumferential cavity which must be completed in a controlled manner prior to the inlet plane of the turbine rotor. Furthermore, the temperature distribution at the exit of the vane passage must be controlled to generate high work extraction from the turbine. The primary metrics …

Multidimensional Modeling Of Pyrolysis Gas Transport Inside Orthotropic Charring Ablators, Haoyue Weng

Theses and Dissertations--Mechanical Engineering

During hypersonic atmospheric entry, spacecraft are exposed to enormous aerodynamic heat. To prevent the payload from overheating, charring ablative materials are favored to be applied as the heat shield at the exposing surface of the vehicle. Accurate modeling not only prevents mission failures, but also helps reduce cost. Existing models were mostly limited to one-dimensional and discrepancies were shown against measured experiments and flight-data. To help improve the models and analyze the charring ablation problems, a multidimensional material response module is developed, based on a finite volume method framework. The developed computer program is verified through a series of test-cases, …

Theoretical Study Of Thermal Analysis Kinetics, Yunqing Han

Theses and Dissertations--Mechanical Engineering

In the past decades, a great variety of model fitting and model free (isoconversional) methods have been developed for extracting kinetic parameters for solid state reactions from thermally stimulated experimental data (TGA, DSC, DTA etc.). However, these methods have met with significant controversies about their methodologies. Firstly, model-fitting methods have been strongly criticized because almost any reaction mechanism can be used to fit the experimental data satisfactorily with drastic variations of the kinetic parameters, and no good criterion exists to tell which mechanism is the best choice. Secondly, previous model free methods originated from the isoconversional principle, which is often …

A Metrics-Based Sustainability Assessment Of Cryogenic Machining Using Modeling And Optimization Of Process Performance, Tao Lu

Theses and Dissertations--Mechanical Engineering

The development of a sustainable manufacturing process requires a comprehensive evaluation method and fundamental understanding of the processes. Coolant application is a critical sustainability concern in the widely used machining process. Cryogenic machining is considered a candidate for sustainable coolant application. However, the lack of comprehensive evaluation methods leaves significant uncertainties about the overall sustainability performance of cryogenic machining. Also, the lack of practical application guidelines based on scientific understanding of the heat transfer mechanism in cryogenic machining limits the process optimization from achieving the most sustainable performance.

In this dissertation, based on a proposed Process Sustainability Index (ProcSI …

Heat Transfer Characteristics In Wildland Fuelbeds, Justin English

Theses and Dissertations--Mechanical Engineering

The fundamental physics governing wildland fire spread are still largely misunderstood. This thesis was motivated by the need to better understand the role of radiative and convective heat transfer in the ignition and spread of wildland fires. The focus of this work incorporated the use of infrared thermographic imaging techniques to investigate fuel particle response from three different heating sources: convective dominated heating from an air torch, radiative dominated heating from a crib fire, and an advancing flame front in a laboratory wind tunnel test. The series of experiments demonstrated the uniqueness and valuable characteristics of infrared thermography to reveal …

Thermal Conductivity Of Alumina And Silica Nanofluids, Julian Bernal Castellanos

All Graduate Theses, Dissertations, and Other Capstone Projects

This thesis studies the effects of the base fluid, particle type/size, and volumetric concentration on the thermal conductivity of Alumina and Silica nanofluids. The effects of base fluid were observed by preparing samples using ethylene glycol (EG), water, and mixtures of EG/water as the base fluid and Al2O3 (10 nm) nanoparticles. The particles type/size and volumetric concentration effects were tested by preparing samples of nanofluids using Al2O3 (10nm), Al2O3 (150nm), SiO2 (15 nm), and SiO2 (80 nm) nanoparticles and ionized water as base fluid at different volumetric concentrations. All samples were mixed using a sonicator for 30 minutes and a …