Engineering Commons^™

Enhanced Heat Transfer Performance By Shape Optimization Of A Non-Axisymmetric Droplet Evaporating On A Heated Micropillar, Haotian Wu

McKelvey School of Engineering Theses & Dissertations

Abstract

Enhanced Heat Transfer Performance by Shape Optimization of a Non-axisymmetric Droplet Evaporating on a Heated Micropillar

By

Haotian Wu

Department of Mechanical Engineering and Materials Science

Washington University in St. Louis, 2019

Research Advisor: Professor Damena Agonafer

The stacked multilayer 3D IC structure used in next generation high-powered electronics poses great challenges in dissipating their large heat flux, which causes extreme difficulties for traditional cooling technologies. In response, more advanced two-phase liquid cooling technologies, such as droplet evaporation, which utilizes the latent heat of vaporization to remove excessive heat, have been widely investigated. Compared to traditional single-phase cooling techniques, …

Energy Modelling To Evaluate The Thermal Regulation Of Aquaculture Raceways Using Geothermal Heat Exchange, Mitchell H. Kuska

Electronic Thesis and Dissertation Repository

Raceways are used in the aquaculture industry to farm fish species that swim against an upstream current. Raceways often draw water from a large waterbody and hence, their temperature changes due to seasonal variation, which directly affect the production yield. This study investigates a novel approach to regulate the raceway water temperature in a sustainable way by utilizing geothermal energy exchange. Energy models were developed to simulate heat transfer in a geothermal borehole heat exchange system and in the raceway system. The two models were then coupled to simulate the thermal regulation of the raceway water via borehole heat exchangers. …

Numerical And Semi-Analytical Estimation Of Convective Heat Transfer Coefficient For Buildings In An Urban-Like Setting, Anwar Demsis Awol

Electronic Thesis and Dissertation Repository

Urban building arrangements such as packing density, orientation and size are known to influence the microclimate surrounding each building. Studies on the impact of urban microclimatic changes on convective heat transfer coefficient (CHTC) from a stock of buildings, however, have been rare in surveyed literature. The present study focuses on numerical and analytical investigation of CHTC from building-like models with homogeneous set of equal and unequal planar and frontal densities. Consequently, the study discusses the CHTC response in relation to broader changes in the urban surface form. Part of the process involves the development of a simplified one-dimensional semi-analytical CHTC …

The Investigation Of Noise, Vibrations And Emissions Of Aero-Gas Turbine Combustion With Synthetic Kerosene Fuels, Margaret Kilpatrick

Honors College Theses

Climatic changes from aviation emissions are complex and include effects of greenhouse gases such as: CO2, NOx, and aerosols. For that reason, the objectives of this study were to investigate the noise, vibrations and emissions characteristics of synthetic kerosene combustion in an aerospace gas turbine to reduce the engine’s environmental impact. Sustainably produced synthetic kerosene is known for having low soot emissions due to little to no aromatics (compounds that create particle pollutants), and for being a sustainable alternative fuel source to imported oil. The noise and sound levels were collected using Bruel & Kjaer microphones to measure various mid …

Critical Radius Of Insulation, Maria N. Ambrose, Samuel J. Sayre, Travis W. Martin, Matt T. Sterling

Mechanical Engineering

The critical radius of insulation is a counterintuitive concept within the study of heat transfer. The theory states that adding insulation to a cylindrical or spherical object will increase the rate of heat loss rather than decrease it, if the radius (thickness) of the insulation is at its “critical” value. The Critical Radius of Insulation Senior Project is designed to demonstrate this phenomenon to Heat Transfer students via a portable apparatus. The concept will be demonstrated with a cylindrical object which is heated by way of a separate voltage source. Thermocouples will display the temperature of the cylinder while insulation …

Waste Gasification, Glyn D. Lewis, Nash Taylor, Nicholas L. Ordonez, David S. Mccallum

Mechanical Engineering

This document summarizes the work the IGT Team has conducted on the topic of waste to energy gasification over the Cal Poly Winter, Spring, and Fall quarters of 2019. The project is being carried out by four Cal Poly Mechanical Engineering students: Nash Taylor, Glyn Lewis, David McCallum, and Nicholas Ordonez and the sponsor of this project is Tod duBois. The team’s original goal was to successfully create a system that compiles residential solid waste on a small scale, gasifies it, and measures the typical syngas outputs, so that the team may assess the viability of gasification of household waste …

Calculation Of Scalar Isosurface Area And Applications, Kedar Prashant Shete

Masters Theses

The problem of calculating iso-surface statistics in turbulent flows is interesting for a number of reasons, some of them being combustion modeling, entrainment through turbulent/non-turbulent interfaces, calculating mass flux through iso-scalar surfaces and mapping of scalar fields. A fundamental effect of fuid turbulence is to wrinkle scalar iso-surfaces. A review of the literature shows that iso-surface calculations have primarily been done with geometric methods, which have challenges when used to calculate surfaces that have high complexity, such as in turbulent flows. In this thesis, we propose an alternative integral method and test it against analytical solutions. We present a parallelized …

On The Fuel Spray Applications Of Multi-Phase Eulerian Cfd Techniques, Gabriel Lev Jacobsohn

Masters Theses

Eulerian-Eulerian Computational Fluid Dynamics (CFD) techniques continue to show promise for characterizing the internal flow and near-field spray for various fuel injection systems. These regions are difficult to observe experimentally, and simulations of such regions are limited by computational expense or reliance on empiricism using other methods. The physics governing spray atomization are first introduced. Impinging jet sprays and Gasoline Direct Injection (GDI) are selected as applications, and modern computational/experimental approaches to their study are reviewed. Two in-house CFD solvers are described and subsequently applied in several case studies. Accurate prediction of the liquid distribution in a like-doublet impinging jet …

Validation Of Rhocentralfoam For Engineering Applications Of Under-Expanded Impinging Free Jets, Peter Nielsen

Electronic Thesis and Dissertation Repository

A numerical validation study of under-expanded impinging jet is conducted using OpenFOAM, an open-source computational fluid dynamics (CFD) library. RhoCentralFoam, a density based, compressible flow solver with a two-equation shear stress transport (SST) turbulence model is used on an axisymmetric model to reduce the computation cost. Major features of the flow were compared to an experimental study by Henderson et al., with a nozzle pressure ratio (NPR) of 4.0 and nozzle to plate spacing between 1.65-4.16. Of the features measured, the Mach diamond spacing, super-sonic core, and shear layer are all accurately predicted, while the recirculation bubble in the impingement …

Thermoplastic Composite Heat Recovery Ventilator, Keegan Guinn

Honors Theses

Heat recovery ventilation continues to increase in importance as building codes mandate reduced air infiltration and increased energy efficiency. Heat recovery ventilators are able to reduce building heating and cooling loads by transferring heat between the exiting air and incoming ventilation air. In the role of heat recovery ventilation, additively manufactured polymer composite heat recovery ventilators offer significant advantages over traditionally manufactured metallic alloy heat recovery ventilators. Through the implementation of additive manufacturing, the internal geometry of the heat recovery ventilator can be optimized to decrease the head loss across the system and features to improve heat transfer such as …

Atmospheric Water Harvesting: An Experimental Study Of Viability And The Influence Of Surface Geometry, Orientation, And Drainage, Carson T. Hand

Master's Theses

Fresh water collection techniques have gained significant attention due to global dwindling of fresh water resources and recent scares such as the 2011-2017 California drought. This project explores the economic viability of actively harvesting water from fog, and techniques to maximize water collection. Vapor compression and thermoelectric cooling based dehumidifier prototypes are tested in a series of experiments to assess water collection capability in foggy environments, and what parameters can increase that capability. This testing shows an approximate maximum collection rate of 1.25 L/kWh for the vapor compression prototype, and 0.32 L/kWh for the thermoelectric cooling prototype; compared to 315 …

Surface Engineering Solutions For Immersion Phase Change Cooling Of Electronics, Brendon M. Doran

Master's Theses

Micro- and nano-scale surface modifications have been a subject of great interest for enhancing the pool boiling heat transfer performance of immersion cooling systems due to their ability to augment surface area, improve wickability, and increase nucleation site density. However, many of the surface modification technologies that have been previously demonstrated show a lack of evidence concerning scalability for use at an industrial level. In this work, the pool boiling heat transfer performance of nanoporous anodic aluminum oxide (AAO) films, copper oxide (CuO) nanostructure coatings, and 1D roll-molded microfin arrays has been studied. Each of these technologies possess scalability in …

Modeling The Effect Of A Compartment Fire On Spaces Adjacent To A Bulkhead With And Without Attachments, Carl E. Hendrickson Ii

University of New Orleans Theses and Dissertations

Structural fire protection is an integral component of shipboard fire safety. There are national and international regulations that delineate requirements for the insulation placed throughout ships. The attachments that penetrate the insulation for hanging wires and pipes can disrupt the integrity of the division, and cause a failure to adhere to the regulations. This problem will be analyzed by using a simplified lumped capacitance model and ANSYS FLUENT CFD. A standard time-temperature fire curve is applied to the fire side of the enclosure. The thermal conductivity of the insulation and steel are made to be temperature dependent. The density of …

Repurposing Plastic Waste In El Cercado, Joseph Dooling, Kirby Townsend, Brendan Smith

Honors Thesis

This project aims to assist the community of El Cercado in the Dominican Republic in turning their plastic waste into useful products. The design team developed a first iteration shredder, injector, and aluminum mold which future design teams could further iterate in order to make products out of waste plastic. Different products were researched to ensure that they can be sold or used in the community. The goal of producing these items is to stimulate economic activity in the community by creating economic opportunity. The design shall also be sustainable in three ways. It shall reuse plastic waste while also …

Insulated Solar Electric Cooker With Phase Change Thermal Storage Medium, Justin Brett Unger, Nathan Robert Christler, Matthew Weeman, Marcus Edward Strutz

Mechanical Engineering

This final design review document outlines the senior design project carried out by a team of four mechanical engineering students at the California Polytechnic State University – San Luis Obispo under the sponsorship of Dr. Peter Schwartz of the Cal Poly Physics department. The aim of this project was to improve upon the design of previously developed Insulated Solar Electric Cookers (ISECs) by adding a thermal storage system to allow for quicker cook times and the ability to cook food at non-peak solar hours. The team’s goal was to develop a working prototype utilizing a phase change medium as the …

Vaccine Cooler For The Global Poor, Benjamin J. Larson, Cooper E. Gibson, Eilbron Younan, Cody R. Volk

Mechanical Engineering

Cal Poly physics professors Peter Schwartz and Nathan Heston approached the Solar Freeze team with the problem that remote communities in Africa have limited access to modern-day medicine or vaccines. They suggested that we try and design a cooling device that can keep vaccines cold for multiple days at a time while the medicine is transported to remote villages. Currently, there are vaccine cooler products on the market, but most of them are very expensive or lack portability. Peter and Nate have tasked the Solar Freeze team to come up with a less expensive solution that is also portable and …

Experimental Investigation Of The Manufacture Of Tunable Graphene Oxide Filter Membranes Using Intense Pulse Light, Joshua H Kotter

Electronic Theses and Dissertations

Reduced graphene oxide is a thin, strong, and inexpensive material with a channel and pore structure that make it a promising candidate for a filtration material. Reduced graphene oxide has been produced and tested in the laboratory, but a lack of scalable manufacturing techniques have limited its commercial use.

This thesis has shown that graphene oxide can be rapidly manufactured with an industrially scalable flash reduction process. The flash reduction process uses 0.58 millisecond pulses from a xenon lamp to reduce the graphene oxide film in less than a minute. Results for partially reduced graphene oxide membranes tuned by the …

Cpu Cooling Pulse Device For Enhanced Heat Transfer, Hannah Farabee, Noémie L. Iñiguez, Hugo Nunez, Wendy Zwanka

Senior Theses

Ice Dragon Cooling is a company which researches thermofluids and heat transfer technologies. The company’s present research focuses on HVAC and computer applications, with an emphasis on nanofluid development. To support Ice Dragon’s mission, the company wants a product that enhances heat transfer efficiency in liquid-cooled CPU systems. The product is to be a pulse device which increases the turbulence of a liquid across a computer CPU cooling block, thereby expediting heat transfer away from the CPU.

The needs for Ice Dragon Cooling were determined based on engineering knowledge and industry consultation. After further analysis, it was determined that increasing …

Design & Evaluation Of Cooling Systems For Photovoltaic Modules, Peter Leary

Honors Theses

There is a persistent need for further development and implementation of renewable energy sources, such as wind and solar. Due to the increase in global population, the disappearance of fossil fuels, and the reality of climate change, renewable power is needed now more than ever. One such renewable power technology is solar photovoltaic, otherwise known as PV. These modules work via silicon cells which are as semiconductors, outputting electrical energy when incident with solar radiation. This is done by separating electrons and protons within the cell. One of the largest issues with PV technology is that there is a linear …

A Study Of Thermal Energy Storage Of Phase Change Materials: Thermophysical Properties And Numerical Simulations, Kyung-Eun Min

Dissertations and Theses

A Thermal Energy Storage (TES) system is meant for holding thermal energy in the form of hot or cold materials for later utilization. A TES system is an important technological system in providing energy savings as well as efficient and optimum energy use. The main types of a TES system are sensible heat and latent heat. A latent heat storage is a very efficient method for storing or releasing thermal energy due to its high energy storage density at constant temperatures, and a latent heat storage material can store 5-14 times more heat per unit volume than a sensible heat …

Flow Behavior In Radial Rotating Detonation Engines, Scott A. Boller

Theses and Dissertations

Recent progress has been made in demonstrating Radial Rotating Detonation Engine (RRDE) technology for use in a compact Auxiliary Power Unit with a rapid response time. Investigation of RRDEs also suggests an increase in stable operating range, which is hypothesized to be due to the additional degree of freedom in the radial direction which the detonation wave can propagate. This investigation seeks to determine if the detonation wave is in fact changing its radial location. High speed photography was used to capture chemiluminescence of the detonation wave within the channel to examine its radial location, which was found to vary …

Examination Of Flow Dynamics And Passive Cooling In An Ultra Compact Combustor, Tylor C. Rathsack

Theses and Dissertations

The Ultra Compact Combustor (UCC) promises to greatly reduce the size of a gas turbine engine’s combustor by altering the manner in which fuel is burnt. Differing from the common axial flow combustor, the UCC utilizes a rotating flow, coaxial to the engine’s primary axis, in an outboard circumferential cavity as the primary combustion zone. The present study investigates two key UCC facets required to further this combustor design. The first area of investigation is cooling of the Hybrid Guide Vane (HGV). This UCC specific hardware acts as a combustor center body that alters the exit flow angle and acts …

Adding Semi-Structured Automated Grid Generation And The Menter-Shear Stress Turbulence Transport Model For Internal Combustion Engine Simulations To Novel Fem Lanl Combustion Codes, Brad Montgomery Philipbar

Mechanical Engineering ETDs

The addition of GridPro semi-structured, automated generation of grids for complex moving boundaries for combustion engine applications and the Menter Shear Stress Turbulent Transfer (SST) model are being developed by Los Alamos National Laboratory. The software is called Fast, Easy, Accurate, and Robust Continuum Engineering (FEARCE). In addition to improving the time and effort required to build complex grid geometry for turbulent reactive multi-phase flow in internal combustion engines, the SST turbulence model has been programmed into the Predictor Corrector Fractional-Step (PCS) Finite Element Method (FEM) for reactive flow and turbulent incompressible flow regime validation is performed. The Reynolds-Averaged Navier-Stokes …

Ignition And Extinction Behavior Of Fuels In A Microcombustor, Pawan Sharma

LSU Doctoral Dissertations

Conventional fuel testing device-CFR engine requires large quantities of fuels, which makes it unsuitable for research of small samples of fuels. This current study seeks to address this limitation by using an externally heated microcombustor as an alternative fuel testing device. Mainly three combustion behaviors have been observed inside a microcombustor: strong flames at higher flow rates, Flames with Repetitive Extinction and Ignition (FREI) at intermediate flow rates, and weak flames at marginal flow rates. In previous studies, weak combustion behavior has been proven suitable to study fuel properties from small samples of fuels. Microcombustor experiments typically rely on flame …

High Injection Pressure Dme Ignition And Combustion Processes: Experiment And Simulation, Xiucheng Zhu

Dissertations, Master's Theses and Master's Reports

With nearly smokeless combustion, Dimethyl Ether (DME) can be pressurized and used as a liquid fuel for compression-ignition (CI) combustion. However, due to its lower heating value and liquid density compared with diesel fuel, DME has a smaller energy content per unit volume. To obtain an equivalent energy content of diesel, approximately 1.86 times more quantity of DME is required. This can be addressed by a larger nozzle size or higher injection pressure. However, the effect of high injection pressure on DME spray combustion characteristics have not yet been well understood. In order to fill this gap, spray and combustion …

Composite Recycler: Frame, Alfonso Olivera

All Undergraduate Projects

How can composites be recycled? The Composite Recycler is an ongoing project that started in September 2017. The purpose of this project was to create a machine that will delaminate the composites, cut them, and heat them up to separate the resin from the composites so they can be recycled. A group was put together for the 2018-2019 academic year to further the project as a whole improve the operation of the device. The existing base was used as well as the cutter and the power sources. The upgrades included; a housing to support the transport rollers and changing from …

The Effects Of 3d Printing Parameters And Surface Treatments On Convective Heat Transfer Performance, Lucas N. Pereira

Electronic Theses and Dissertations

Additive manufacturing technology and applications have quickly expanded in many industries over the last five years. As additive manufacturing is studied and refined, improvements in resolution and strength have helped propel further growth of the industry. This study focuses on an additive manufacturing technology called fused filament fabrication (FFF). FFF involves the extrusion and layer-by-layer deposition of a molten thermoplastic material to create the desired part. One potential new application of fused filament fabrication is the manufacture of heat exchangers and heat sinks. This study focuses on developing baseline experimental data related to convective heat transfer coefficients over surfaces of …

Solar Powered Atmospheric Water Generation, Ben Conser

Master’s Theses

Several atmospheric water generation (AWG) system configurations were analyzed to determine the feasibility of AWG as a method to combat water stress. In order to best combat water stress, AWG must be implemented in such a way which minimizes the energetic and monetary cost of water production. Thermodynamic and economic analyses were used to compare the performance of several AWG system configurations. Metrics such as specific energy consumption (SEC) and levelized cost of water (LCOW), which measure the energetic and monetary cost of water production respectively, were used to compare each system. Using this approach, the optimal system configuration was …

Improving The Delivered Specific Impulse Of Composite Rocket Propellant Through Alteration Of Chemical Composition: Methodology And Parameters For Characterization Of Propellant And Validation Of Simulation Software Common To The Amateur Rocketry Community, Isaac O'Brien, Austin Ryan

Williams Honors College, Honors Research Projects

In this study, two solid composite rocket propellants were designed utilizing ProPEP, a rocket propellant formulation software common in the amateur and hobby rocketry communities. The two propellants were designed to optimize specific impulse relative to a literature propellant designed by 1020 Research Labs. The literature propellant was also tested in order to validate the design of experiment as well as the mixing and testing procedures. All three propellants, which includes the literature propellant RCS-P, and the two novel propellants AKR-P1 and AKR-P2 were characterized with static tests. The results of the static tests provide data on propellant performance and …

Optimization And Comparison Of Over-Expanded And Other High Efficiency Four-Stroke Spark-Ignited Boosted Engines, Zhuyong Yang

Dissertations, Master's Theses and Master's Reports

Recent fuel economy and emission regulations are the major concern of the research and development of modern internal combustion engine. Such technologies include variable valve timing (VVT), direct injection (DI), turbocharging, downsizing, and over-expanded cycle are used by many manufacturers to improve engine fuel economy or increase power density.

Current Atkinson cycle technology in the production engine is mainly realized by an advanced valvetrain system to reduce the effective compression ratio while maintaining the same expansion ratio. Another approach to realize over-expanded cycle engine is to utilize a multi-link cranktrain mechanism. Although the Atkinson cycle was originally patented in the …