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Comparison Of Empirical And Analytical Eigenfunctions As Bases For Reduced Order Methods In Heat Transfer, Jakob G. Bates, Matthew R. Jones, Christopher R. Dillon, John Tencer

Student Works

Reduced order methods using spectral representations show promise in facilitating and accelerating heat transfer analyses. This paper proposes a taxonomy for reduced order methods, classifying a method as reduced order compression, modelling, or analysis. The performance of bases formed with analytical and empirical eigenfunctions are compared for representative reduced order tasks. The Akaike Information Criterion is applied in a novel way to compare the performance of these bases. The present study finds that both bases are parsimonious for reduced order compression tasks. Empirical eigenfunctions are more robust to for reduced order modelling with variations in modelling parameters such as thermal …

Thermal Resistance Characterization Of High-Voltage Sic Power Module, Landon Lemmons

Mechanical Engineering Undergraduate Honors Theses

Researchers within the University of Arkansas Electrical Engineering Research Department have embarked on a project aimed at enhancing the thermal performance of high-voltage power modules. To aid in the progress of this project, the design, and development of a thermal tester device are needed. The primary objective of this device is to determine the various thermal properties of high-voltage power modules that the electrical engineering department has developed. Additionally, the project aims to facilitate electrical loading tests on power modules and provide researchers with the means to calibrate the power module in terms of thermal load. This project also possesses …

Design And Characterization Of A High Pressure Flow Loop For Heat Transfer Experiments Of Supercritical Carbon Dioxide, Joseph Sauerbrun

Doctoral Dissertations and Master's Theses

Supercritical carbon dioxide (sCO2) sees heightened heat transfer characteristics near its critical point due to its drastically changing thermophysical properties. Conventional single phase heat transfer theory was not developed to capture this nonlinear variation in properties and cannot predict the heat transfer characteristics of sCO2 to a practical level useful for design. To delve deeper into the behavior near the critical point and shed light on this crucial phenomenon, a state-of-the-art closed flow loop was developed. This setup enabled convective heat transfer experiments of sCO2 under diverse boundary conditions and test section geometries. Key components of the loop include the …

Thermoacoustic Refrigerator, Rees Phillip Verleur, Colleen Farrell Mccandless, Anders Matthew Bjork, Yashraj Ashwinkumar Solanki

Mechanical Engineering

In the Thermoacoustic Refrigerator Cal Poly Mechanical Engineering senior project, we designed, built, and tested a thermoacoustic refrigeration system which achieved an average temperature difference of 11.0°C. Our system consists of a resonator tube with an instrumented stack, mounted onto a base with a speaker and amplifier. An external power supply and function generator provide the power and signal to the system, and a thermocouple reader displays the temperature of the top and bottom of the stack. The system consistently achieved a significant temperature difference between the two ends of the stack in various ambient conditions, and it was quick …

A Systematic Study Into The Design And Utilization Of Burn Wire As A Means Of Tensioning And Releasing Spacecraft Mechanisms Through Applied Joule Heating, Chandler Dye

Mechanical Engineering Undergraduate Honors Theses

The joule heating characteristics of Nichrome burn wires, often used as a thermal cutting device in mechanisms designed to fasten and release CubeSat deployables, are examined in the following thesis. Wires ranging from 0.125 inches to 2 inches long, and diameters of 30 Ga and 40 Ga, are investigated through analytical calculations and thermal simulations based on heat transfer due to joule heating, and through physical circuitry-based experiments. The temperature data is used to generate heating curves to predict the time it takes for Nichrome wires to fail under varying testing parameters. This research aims to catalog a series of …

Frostflex, Isaac Edmondson, Caleb Edmondson, Joey Esker, Nadine Salem

Williams Honors College, Honors Research Projects

Research has shown that the majority of heat lost during physical exercise leaves the body through the hands, feet, and the face. Our design project seeks to develop cooling glove technology to increase the rate at which heat leaves the body during recovery from physical exertion. The goal of this project was to investigate different ways in which heat absorption through various mediums can be manipulated and scaled into an adaptable, flexible design in which athletes of all levels, from recreational to professional, can improve their physical performance with the use of our gloves. Deliverables include a functional prototype, product …

Cryogenic Flow Boiling Heat Transfer On Additively Manufactured Liquid Rocket Engine Cooling Channels, Debra Jazmin Ortega

Open Access Theses & Dissertations

The enhancement of flow boiling heat transfer is critical because it can solve thermal management issues seen across all engineering and manufacturing applications. Even though advancements are being made, more studies are needed to understand the behavior of forced convective boiling further.Currently, there are four major issues in the field of regenerative cooling of liquid rocket engines. 1. The cooling channels are typically manufactured using conventional machining, while aerospace industries are currently exploring the additive manufacturing approach. 2. The experimental critical heat flux values for cryogenic fluids are either lower or very close to the model predictions; however, the effect …

Numerical Investigation Of Flow And Thermal Behavior In Channels With Pcm-Filled Thermal Energy Storage Columns For Potential Application In Photobioreactors, Sameed Akber

Electronic Thesis and Dissertation Repository

Microalgae has been identified as a potential source in the production of biofuel. Photobioreactors, which are used for microalgae production, normally experience temperature variations over the diurnal cycle due to changes in ambient conditions. The thermal regulation of photobioreactors to minimize temperature variations will result in a higher yield of microalgae, which are sensitive to such variations. The present research is aimed to investigate a novel approach to thermally regulate photobioreactors using phase change materials (PCM) where the latent heat of the material is exploited as the energy storage. The present research uses a numerical approach to study the flow …

Droplet Dynamics And Heat Transfer During Condensation On Lubricant-Infused Surfaces, Jianxing Sun

McKelvey School of Engineering Theses & Dissertations

Inspired by pitcher plants, a micro/nano- structured solid surface infused with low-surface-tension lubricant constitutes a novel class of biomimetic surfaces—lubricant-infused surfaces (LISs). Unlike solid hydrophobic and superhydrophobic surfaces, a LIS is “hemi-solid and hemi-liquid”. The thin lubricating film can extraordinarily decrease adhesion and avoid contact line pinning between the working fluid and the underlying solid, displaying many desirable properties, such as excellent liquid repellency, suppression of fouling, and self-healing. Hence, LISs are ideal for applications where liquids or contaminants must be efficiently removed from surfaces in harsh environments. For example, LISs can promote stable dropwise condensation of water or low-surface-tension …

Heat Pipes With Arbitrary Boundary Conditions, Katrina Sweetland

Doctoral Dissertations

Heat pipes passively transfer heat in numerous applications. Traditionally one side of the heat pipe is coupled to a heat source (evaporator) while the opposite side is coupled to a heat sink (condenser). This configuration has working fluid stagnation points at each end of the heat pipe. Other configurations may also prove useful, such as heat pipes with multiple evaporators or multiple condensers. In such heat pipes, additional working fluid stagnation points form at locations dependent on the configuration of the thermal boundary conditions. These stagnation points divide the heat pipe into multiple cells that each have an evaporator and …

Experimental And Numerical Investigation Of Lauric Acid Melting At Suboptimal Inclines, Casey J. Troxler

Doctoral Dissertations and Master's Theses

Validation experiments are the baseline for completing numerical studies for engineering design. Applications of the enthalpy-porosity model have expanded in research with the growth of new technologies such as metal additive manufacturing or the renewed interest in thermal energy storage for supplementing renewable energy. A simplified experiment examining the melting behavior of lauric acid from an isothermal surface has become a common case for validating the performance of numerical models. Several studies of this rectangular experiment have been repeatedly used as model validation in a variety of problem conditions.

The first part of this study presents experimental data for the …

Cool Thermal Energy Storage: Water And Ice To Alternative Phase Change Materials, Sandra K. S. Boetcher

Publications

Cool thermal energy storage has a long history dating back to ancient times with modern developments beginning in the mid-nineteenth century where blocks of ice were cut from frozen lakes for cooling applications. Today, the prevalent mode of thermal energy storage is the utilization of ice tanks in commercial buildings for peak shaving and load shifting. In this chapter, a summary of different types of water/ice thermal energy storage systems is provided; an overview of alternative phase change materials for use in cool thermal energy storage is given; and alternative phase change material thermal energy systems, their implementation, challenges, and …

Responses Of An Axially Rotated Tube Versus Twisted Tube Design As Two Solutions To Enhance The Thermal Performance Under A Non-Uniform Heat Flux Condition: A Numerical Study, Andrew S. Tanious, Ahmed A. Abdel-Rehim, Ahmed A. Attia

Mechanical Engineering

Enhancement of heat transfer in tubes exposed to non-uniform heat flux applications is a key factor in increasing such applications' efficiency.

In the present study, heat transfer in an axially rotating pipe with concentrated heat flux at the lower section of the pipe is numerically investigated and compared to the twisting technique in such applications. The effects of pipe’s length (1, 2, and 3 m) and rotation rate (N = 0–10.5), which is the ratio between the rotational and axial Reynold’s numbers, are studied numerically using ANSYS Fluent while the effect of the twist ratio (S = 0.1–1m) is studied …

Numerical Investigation On The Effect Of Spectral Radiative Heat Transfer Within An Ablative Material, Raghava S. C. Davuluri, Rui Fu, Kaveh A. Tagavi, Alexandre Martin

Mechanical Engineering Faculty Publications

The spectral radiative heat flux could impact the material response. In order to evaluate it, a coupling scheme between KATS - MR and P1 approximation model of radiation transfer equation (RTE) is constructed and used. A Band model is developed that divides the spectral domain into small bands of unequal widths. Two verification studies are conducted: one by comparing the simulation computed by the Band model with pure conduction results and the other by comparing with similar models of RTE. The comparative results from the verification studies indicate that the Band model is computationally efficient and can be used to …

Deep Learning Strategies For Pool Boiling Heat Flux Prediction Using Image Sequences, Connor Heo

Graduate Theses and Dissertations

The understanding of bubble dynamics during boiling is critical to the design of advanced heater surfaces to improve the boiling heat transfer. The stochastic bubble nucleation, growth, and coalescence processes have made it challenging to obtain mechanistic models that can predict boiling heat flux based on the bubble dynamics. Traditional boiling image analysis relies on the extraction of the dominant physical quantities from the images and is thus limited to the existing knowledge of these quantities. Recently, machine-learning-aided analysis has shown success in boiling crisis detection, heat flux prediction, real-time image analysis, etc., whereas most of the existing studies are …

Enhanced Flow Boiling And Bubble Dynamics With Hfe7100 & Di Water In Interconnected Microchannels, Jiaxuan Ma

Theses and Dissertations

Flow boiling in microchannels using dielectric fluids is one of the most desirable cooling solutions for high power electronics. Primary two-flow patterns, including bubbly flow, slug flow, and annular flow, have been well established in microchannels. However, it is challenging to promote flow boiling performance, particularly critical heat flux (CHF), due to their unfavorable thermophysical properties. Considering these situations, flow boiling in parallel and isolated microchannels have been extensively studied. In this dissertation, a novel concept that has five parallel microchannels (W=200 µm, H=250 µm, L=10 mm) are interconnected by micro-slots (20 µm wide and 250 µm deep) starting from …

Experimental Investigation Of Flow And Thermal Behavior In Channels With Pcm-Filled Thermal Energy Storage Columns For Potential Application In Photobioreactors, Kira Toxopeus

Electronic Thesis and Dissertation Repository

Microalgae has been identified as a potential source for the production of biofuels and other bio-products. The growth of microalgae is sensitive to the temperature variations inside the photobioreactor. The present research investigated an innovative approach to thermally regulate photobioreactors by introducing passive thermal energy storage using phase change material (PCM). The research was specifically focused on a novel design to integrate thermal storage in the reactor channel in the form of offset columns containing PCM. Two column shapes were considered: circular and square. The first part of the study was focused on characterizing the influence of offset column shapes …

A Study Of The Efficiency And Effectiveness Of The First Four Iterations Of Sierpinski Carpet Fractal-Like Fins At Increasing Angles In Natural Convection, Sophia N. Fleri

Honors College Theses

Fractal geometries have been found in several studies to increase a fin’s thermal performance. Both the reductions of volume and mass accompanied by an increase in performance are desirable to prevent malfunction of the device through passive heat dissipation. The Sierpinski carpet fractal pattern, beginning with a basic square geometry in which an increasing number of perforations are incorporated through each successive iteration, reduces the fin’s mass while increasing its surface area simultaneously; this increase in surface area increases the rate of heat transfer experienced across the fin. The first four iterations of the Sierpinski carpet pattern, each with identical …

Emissivity Measurements Of Painted And Aerosol Deposited Thermographic Phosphors (Yag:Dy And Mfg:Mn), Wendy Flores-Brito

Mechanical Engineering ETDs

Combustion is one of the most difficult processes to model. Luminous flames are characteristically sooty, which creates a problem when modeling and calculating the combustion and heat transfer of the process; both of which are highly dependent on temperature and emissivity. Soot particle emissivity as well as gas contributions affect the heat transfer calculation and must be accounted for.

Thermographic phosphors (TP) are ceramic based phosphorescent materials that have a temperature dependent emission that can be exploited to obtain surface and gas temperature measurements, as well as 2D temperature maps. Emissivity knowledge is not needed to obtain temperature and is …

Efficient Enhancement Of Micro-Nucleation Rates In Flow-Boiling - By Concurrent Micro-Structuring Of The Boiling-Surface And Its Judicious Energization By Piezoelectric-Transducer Induced Acoustic Vibrations., Atharva Rahane

Dissertations, Master's Theses and Master's Reports

The report describes the science and technology backgrounds and uses for the technology breakthrough reported for enhanced flow-boiling based cooling of high-power density electronics (chips, memory etc.). A controlled but explosive growth in micro-scale nucleation rates during flow-boiling of HFE-7100 (electronics and environment friendly liquid from 3M, Inc) is enabled by the uses of inexpensive meshed-copper for micro-structuring of the boiling surface and a pair of Piezoelectric-transducers for active imposition of suitable acoustic vibrations. The pair of piezo transducers mounted just outside the mini-channel impose “in plane” acoustic vibrations of controllable amplitudes and frequencies, and they are used to induce …

Toward Closing The Urban Surface Energy Balance Using Satellite Remote Sensing, Joshua Hrisko

Dissertations and Theses

The energy exchanges at the Earth’s surface are responsible for many of the processes that govern weather, climate, human health, and energy use. This exchange, commonly known as the surface energy balance (SEB), determines the near-surface thermodynamic state by partitioning the available energy into surface fluxes. The net all-wave radiation is often the primary energy source, while the heat storage and sensible and latent heat fluxes account for the majority of energy distributed elsewhere. While the SEB of various natural environments(trees, crops, soils) has been well-observed and modeled, the urban surface energy balance remains elusive. This is due to the …

Thermal Performance Of Sierpinski Carpet Fractal Fins At Various Angles Of Inclination In A Natural Convection Environment, Haidar Jamil Khalil

Electronic Theses and Dissertations

As technology advances, higher performance cooling systems are desired to meet numerous thermal management challenges. Extended surfaces, also known as heat sinks or fins, are commonly used to passively dissipate unwanted heat from mechanical and electrical systems. Fractal fins in accordance with the first four iterations (including a base iteration) of the Sierpinski carpet, manufactured from AL-5052, were studied along seven different inclinations from 0° (orientated perpendicular to the direction of gravity) to 90° (orientated parallel to the direction of gravity), in iterations of 15°. The purpose of study was to investigate the thermal performance of the first four fractal …

Quantification Of Heat Flows Through Building Entrance Doors On A Winter Day, Daeho Kang

Publications and Research

The current methods for the prediction of the heat flow through building entrance doors have been used for years while involved with a certain degree of uncertainty. This paper describes an experimental method that accurately quantified such heat flow. The experiment monitored local environmental parameters in a college building on a cold winter day. The results of the experiment demonstrated that the experimental method is viable to accurately estimate the heat flow throughout the entrance doors and the presence of a vestibule moderated heat losses from the conditioned area. The results will be used for validating the existing methods.

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 …

Duocel Metal Foam Display Cases, Kate Goldsworthy, Katherina Prodanov, Benjamin Swanson, Syed Hasan

Mechanical Engineering

This Final Design Review (FDR) report outlines the senior design project that was conducted by a team of four mechanical engineering students at California Polytechnic State University-San Luis Obispo for ERG Materials and Aerospace Corporation. The goal of this project was to design displays that showcase the properties of ERG’s Duocel® foam at tradeshows and client meetings. To better understand the needs of our sponsor, the team researched Duocel®’s capabilities, related technologies, and relevant standards and regulations. With this information, we further defined the problem by creating a problem statement and a set of engineering specifications through a Quality Function …

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 …

Analytical Modeling And Life Cycle Assessment Of A Solar Powered Vapor Absorption Cooling System, Harold A. Walters

Electronic Theses and Dissertations

Vapor absorption cooling systems (VACS) offer an environmentally friendly alternative to the standard vapor compression cooling systems (VCCS) for cooling homes, businesses, factories, and other buildings. VACS use low-grade thermal energy to achieve a cooling effect and require minimal electrical input for the liquid solution pump used for circulation within the system. The thermal energy which powers these systems can be provided through several means; one popular form is through the use of solar thermal collectors. This paper provides a process for determining the overall size and configuration of the VACS depending upon the operating conditions of selected components. A …

Experimental And Numerical Study Of The Stirling Engine Robust Foil Regenerator, Koji Yanaga

Graduate Theses, Dissertations, and Problem Reports

The regenerator is located between the heat accepter and the heat rejecter of the Stirling engine. It works as a thermal energy storage component in the engine. Most of the regenerators are made of woven screen or random fiber. However, the flow going through the woven screen or random fiber is similar to the cylinders in crossflow which has flow separation. To achieve higher engine efficiency, it is required to design a regenerator which has higher convective heat transfer, lower pressure drops. Therefore, a parallel channel regenerator called a robust foil regenerator was designed and manufactured.

In this study, a …

Investigation Of Heat Exchanger Effectiveness Using A Surface Coating Technology, Allen Duffy

Graduate Theses, Dissertations, and Problem Reports

Diesel engine manufacturers continue to improve engine performance through increased thermal efficiency and reduced regulated emissions. The aftercooler located between the turbocharger air outlet and intake manifold experiences a wide range of operating conditions. Improving the heat transfer characteristics in the aftercooler can lead towards improved engine performance through increased charge air density. A surface coating has been proposed to enhance the heat transfer characteristics for a marine-based application on the water - side of the heat exchanger. To evaluate the efficacy of the coating, the rate of heat transfer with and without the coating was quantified in a controlled …

Laser Ablation Of Aluminum, Erika Nosal, Zachary Rahe, Arthur Pamboukis

Williams Honors College, Honors Research Projects

The laser ablation of metal carries relevance in a variety of engineering industries. This includes, but is not limited to, processes such as micromachining, or implementation on aircraft weaponry. The latter application is the reasoning for why aluminum is the specific metal in consideration, as it is commonly used for the construction of aircraft components.

The scope of this project was to optimize the energy dispersed through laser ablation on aluminum by mathematical modeling. The transient conduction process in the aluminum was modeled using a 2-dimensional cylindrical coordinate system in both MATLAB and ANSYS/Fluent. These models were adopted to simulate …