Mechanical Engineering Commons^™

Analysis Of Approximations In Flash Thermal Diffusivity Measurements Using High‑Fidelity Simulations, Tage T. Burnett, Jakob G. Bates, Matthew R. Jones, Christopher R. Dillon, John Tencer

Faculty Publications

Thermal diffusivity is an important material property for understanding and characterizing transient behavior in many heat transfer applications. This study investigates the accuracy and approximations of inverse mathematical models for measuring thermal diffusivity of materials via the widely used Flash Method. High-fidelity simulations of the Flash Method in copper, silicon carbide, silicon, and glass were performed as numerical experiments and included physics such as in-depth absorption, radial conduction, and surface convection. Data from those numerical experiments were used to estimate material thermal diffusivity using seven traditional and new inverse models. Parker’s original model had relative errors 𝜖< 5% when the approximations it makes were enforced in numerical experiments. Newer models performed well even when experimental restrictions were relaxed. Models that include radial heat conduction were capable of accurately measuring thermal diffusivity (𝜖< 1%) when a Gaussian energy source was used. Models with radial conduction and in-depth material absorption of the laser source could calculate thermal diffusivity for semi-transparent materials such as silicon (𝜖< 1%) and even transparent materials like glass (𝜖< 10%). Convective losses from the material’s front surface had a negligible impact on measurements except for very low thermal diffusivity materials. Using temperatures from many locations of the test material’s surface increased resilience to noise, reducing the distribution of thermal diffusivity measurements by more than an order of magnitude. The models developed in this study could enable a more relaxed Flash Method experimental setup that maintains thermal diffusivity accuracy and extend the utility of the Flash Method to semitransparent materials.

Numerical Investigation Of Heat Transfer And Aero-Acoustic Response In Deep Cavity Flows Using Urans Simulations, Abdul Hamid Jabado, Ali Hammoud, Bilal El Zohbi, Bilal Taher, Hassan Assoum

BAU Journal - Science and Technology

This paper presents a numerical study to investigate a deep cavity flow, in order to better understand the underlying mechanisms involved in it, such as flow dynamics, heat transfer, and aeroacoustics. A 2-D Unsteady Reynolds Averaged Navier Stokes model (URANS) was implemented using an SST k-ω turbulence closure simulated over a rectangular deep cavity. Previous experimental results were used to validate the numerical results, to confirm the accuracy of the flow field patterns reproduced. Both controlled and uncontrolled cases were analyzed. Heat transfer was also investigated on both configurations, showing the effect of cavity geometry and inlet conditions on heat …

Thermal Radiation Effects On Particles From Plasma Arc Radiation, Reece Davis, Joseph Mcgee

Williams Honors College, Honors Research Projects

Understanding the radiation heating and transport of both microparticles and nanoparticles is a phenomenon that is critical for both space and Earth sciences. In space, these particles are heated by plasma arcs within ionized space clouds or solar flares and can be present the path of deep space missions and orbital satellites. While on Earth, processes such as forest fires, nuclear fusion, and microchip manufacturing include the plasma arc heating of particles. These particles lay within the Mie Scattering Regime and Rayleigh Scattering Regime and emit radiation differently based on their diameter. New mathematical and computational modeling has been conducted …

Impact Of Slot Liner Compression On The Total Thermal Resistance Of The Stator-Winding Assembly In Electric Motors, Lindsay Sutherland

The Journal of Purdue Undergraduate Research

The increasing demand for high-performance electric motors, driven by the rapid adoption of electric vehicles, necessitates effective thermal management techniques that improve their safety, efficiency, and reliability. Heat must be transferred from the current-carrying copper windings to the metallic stator body through an electrically insulating material called the slot liner. However, little research has focused on the interactions between the slot liner and the windings. This study examines the impact of slot liner compression on the thermal resistance across the stator-winding assembly considering two common slot liners: Nomex® 410 and Kapton® MT+. A mock stator-winding assembly was developed by stacking …

The Effect Of Preheater On Heat And Mass Transfer Efficiency Using Rotating Drum Roaster, Melisa Surya Andini, Retno Wulandari, Heru Suryanto

Journal of Mechanical Engineering Science and Technology (JMEST)

Indonesia is the third-largest coffee producer globally, facing challenges including rising raw material costs, increased energy consumption, and unpredictable weather conditions. One potential solution is optimizing energy efficiency during roasting. This study investigates the effect of preheating on time and energy efficiency in heat and mass transfer by utilizing waste heat to preheat green Robusta coffee beans. The experiment was conducted on a laboratory scale using a rotating drum roaster with a double-layer drum made of stainless steel and clay, at 200 °C under atmospheric pressure. Two treatments were applied: roasting with a preheater and without, each repeated three times …

Heat Transfer Enhancement In Cold Plate Heat Exchangers With Trapezoidal Vortex Generators, Montgomery Miller

Student Theses and Dissertations

An experimental investigation was carried out to study the effects of trapezoidal vortex generators (VGs) as a method of thermal enhancement within cold plate heat exchangers. Three different cold plates were imbedded with VGs in the bottom of the flow passage of varying sizes (h/H = 0.195, 0.253, 0.36) and quantity, as well as a cold plate with no VGs to be used as a comparative baseline. Testing was conducted under the laminar, transitional, and turbulent flow regime (Re = 1000 to 5500) using distilled water as the coolant. Experimental results indicate that the addition of VGs provide a positive …

Experimental Investigation Of Heat Transfer To Tightly Packed Cylinder Arrays, Cameron M. Sexsmith

Doctoral Dissertations and Master's Theses

With the increased emphasis on the development of hybrid electric aircraft and other electric driven vehicles, the thermal demand on batteries is increasing. Unique to the aviation sector is the combined need of high battery thermal loads and a light-weight thermal management system. A proposed configuration is an array of batteries directly cooled with a dielectric coolant. The knowledge of heat transfer characteristics of battery cooling is becoming an ever pressing issue due to the need to optimize volume and mass in a safe manner. Tighter spacings between batteries provide higher pack densities, however, at the cost of increased cooling …

Range And Accuracy And Of In-Plane Anisotropic Thermal Conductivity Measurement Using The Laser-Based Angstrom Method, Aalok U. Gaitonde, Justin A. Weibel, Amy M. Marconnet

CTRC Research Publications

High heat fluxes in electronic devices must be effectively dissipated to prevent local hotspots, which are critical for long-term device reliability. In particular, advanced semiconductor packaging trends toward thin form factor products increase the need for understanding and improving in-plane conduction heat spreading in anisotropic materials. The 2D laser-based Ångstrom method, an extension of traditional Ångstrom and lock-in thermography techniques, measures in-plane thermal properties of anisotropic sheet-like materials. This method uses non-contact infrared temperature mapping to measure the thermal response to periodic laser heating at the center of a suspended sample. The spatiotemporal temperature data are analyzed via an inverse …

Novel Design And Fabrication Of A High-Speed Transient Heat Flux Sensor For Application To Rotating Detonation Engines, Zachary Todd Tallman

Graduate Theses, Dissertations, and Problem Reports (ETD)

Rotating detonation engine (RDE) combustion systems have been a topic of interest in the pressure gain combustion community for their benefits over traditional gas turbine engine combustors. However, cooling requirements for these engines are significantly higher and less predictable than those of non-detonating engines. To understand and quantify the high-speed heat transfer dynamics within an RDE, a novel high-frequency heat flux sensor is presented. This study aims to design a robust, single-sided sensor that can withstand the high temperature and harsh environment of an RDE for extended durations. Screen printing is used to deposit a layered, platinum-yttria-stabilized zirconia (YSZ) film …

Improving Thermionic Power Generation Via The Reduction Of Emission Barriers, Chace E. Franey

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

This thesis investigates methods to improve the performance of thermionic energy converters (TECs) by reducing the emission barriers. A TEC generates electricity from thermal energy when electrons are emitted from a hot electrode (the emitter) through a vacuum gap and absorbed by a cooler electrode (the collector). Due to their lack of working fluids and inherently compact nature, TECs have garnered attention over the years for their potential as a means of power generation in space or high-grade waste heat recovery. Historically, however, the practical implementation of TECs has been hindered by significant technical challenges. Recent advancements in microfabrication techniques …

Effects Of Fluid Slip On Heat Transfer In The Thin Film Region In A Microchannel, Rama S. R. Gorla, John Brewer, Abdeel Roman

Faculty Publications

A theoretical study was undertaken to investigate the influence of interfacial slip on evaporation of a thin liquid film in a microfluidic channel. The disjoining pressure and the capillary force which drive the liquid flow at the liquid-vapor interface in thin film region are adopted. The evaporating thin film region is an extended meniscus beyond the apparent contact line at a liquid/solid interface. Thin film evaporation plays a key role in a highly efficient heat pipe. Slip length was found to affect the heat transfer in the microchannel by altering the thin film geometry.

Numerical Modeling Of Thermal Runaway In Lithium-Ion Batteries Using Decomposition Kinetics And Inter-Cell Contact Resistance, Shehzad Khan

College of Graduate Studies: Theses & Dissertations

Lithium-ion batteries (LIBs) are central in numerous high-demand applications due to their high energy density and prolonged cycle life. Despite these advantages, their susceptibility to thermal runaway (TR) poses a significant safety risk, with the potential for catastrophic failures. This study focuses on the thermal behavior of prismatic lithium-ion cells, using a finite volume-based partial differential equation (PDE) solver developed in MATLAB and JULIA to model TR behavior. This solver accurately simulates transient behaviors, convection, diffusion, and source terms across various coordinate systems. By engaging in a series of increasing complex case studies, this research aims to identify the critical …

Thermal Atomization On Superhydrophobic Surfaces Of Varying Temperature Jump Length, Eric D. Lee, Daniel Maynes, Julie Crockett, Brian D. Iverson

Faculty Publications

This paper presents an experimental study of drop impingement and thermal atomization on hydrophobic and superhydrophobic (SH) surfaces. Superhydrophobic surfaces having both microscale and nanoscale geometry are considered. Microscale SH surfaces are coated with a hydrophobic coating and exhibit micropillars and cavities which are classified using the surface solid fraction and center to center pitch. The solid fraction and pitch values explored in this study range from 0.05-1.0 and 8-60 μm respectively. Nanoscale textured surfaces are created by applying a blanket layer of carbon nanotubes. Both types of surfaces are further classified by a temperature jump length (λ …

Evaluation Of Digital Twin Approaches For Thermal Modeling And Energy Optimization For Existing Buildings, Jason Bastie Muermann

Theses and Dissertations

Residential, commercial, and industrial building sectors in the United States were responsible for 42% of the nation’s consumption of 100.2 quadrillion BTUs of energy in 2019 [1]. 80% of the nation’s energy is sourced from fossil fuels, including coal, natural gas, and petroleum. Fossil fuels are known contributors to carbon emissions and climate change, making energy reduction vital. Consequently, New Jersey Department of Military and Veterans Affairs (NJDMAVA) is tasked with evaluating energy consumption and efficiency in all New Jersey Army National Guard (NJARNG) facilities, as mandated by TAG Policy Letter 18-5, Executive Order 13990, and the Energy Independence and …

Modeling Of Heat And Mass Transfer In Flat Heat Pipes, Salar Saadatian

LSU Doctoral Dissertations

Phase-change phenomenon is ubiquitous in nature and widely utilized in thermal management of computer chips. Flat heat pipes have been extensively used in thermal management of microelectronic devices. However, existing research mainly concentrates on developing numerical models and lacks a systematic analytical approach to elucidate the working mechanism of flat heat pipes. We consider a horizontal flat heat pipe with an idealized porous wick. The pores in the wick are straight circular capillaries running along and across the wick and are filled with a liquid. The rest of the pipe is filled with its vapor. The mass evaporative rate at …

Measurement Of Conduction, Radiation, And Convection Thermal Energy To Assess Baking Performance In Residential Ovens., Sean Simpson

Electronic Theses and Dissertations

Residential ovens are complicated thermal environments capable of delivering convection, conduction, and radiation heat transfer to food. The amount and mode of heat transfer can change based on the design of the oven cavity, cooling systems, and oven cycle algorithms. Studies have shown that the changes in one heat transfer mode can have an impact on the quality of baked goods. The many variables involved make designing residential ovens a time consuming and costly process. The goal of this study is to adapt thermal energy sensing technology to collect energy data from a residential oven and develop correlations to quality …

Investigation Of Pool Boiling Heat Transfer On Modified Copper And Aluminum Surfaces, Mariam Khaled Zaghloul

Theses

This thesis presents an investigation of pool-boiling heat transfer using the surfacemodification method. The studied boiling surfaces were smooth and rough pin-fins embedded on the copper and aluminum surfaces. This study visualizes bubble formation and departure diameter. Experimental testing aims to predict the heat transfer coefficients for different heat fluxes over smooth and rough pin-finned surfaces. The surface modification method allows changing the boiling surface characteristics, which can lead to enhanced heat transfer. Several factors were studied, including the heat-transfer coefficient, heat flux, bubble departure diameter, and formation time. Four surfaces were used for conducting the pool boiling experiment: a …

Advances In Spacecraft Thermal Control, Sandra K. S. Boetcher, Robert C. Consolo Jr.

Publications

Spacecraft thermal management is critical for ensuring mission success, as it affects the performance and longevity of onboard systems. A comprehensive overview of the state of the art in spacecraft thermal control solutions, as well as a design methodology framework for efficient and effective thermal management, is provided. Various thermal control solutions, including coatings, insulation, heat pipes, phase-change materials, conductive materials, thermal devices, actively pumped fluid loops, and radiators, are discussed along with the primary sources of heat loading in space. The need for accurate modeling and analysis of the thermal environment to identify appropriate thermal control solutions and design …

Direct Spectroscopic Observation Of Cross-Plane Heat Transfer In A Two-Dimensional Van Der Waals Heterostructure, Du Chen, Matthieu Fortin-Deschênes, Yuchen Lou, Huiju Lee, Kenji Watanabe, Takaaki Taniguchi, Fengnian Xia, Peijun Guo, Multiple Additional Authors

Mechanical and Materials Engineering Faculty Publications and Presentations

Two-dimensional (2D) transition metal chalcogenides (TMDs) have drawn significant attention in recent years due to their extraordinary optical and electronic properties. As heat transfer plays an important role in device performance, various methods such as optothermal Raman spectroscopy and time-domain thermoreflectance have been developed to measure the thermal conductivity and interfacial thermal conductance in 2D van der Waals (vdW) heterostructures. Here, we employ the vibrational-pump-visible-probe (VPVP) spectroscopy to directly visualize the heat transfer process in a heterostructure of multilayer h-BN and monolayer WS2. Following an impulsive vibrational excitation of h-BN in the mid-infrared, we probe the heat transfer …

Heat Transfer In Microchannel Compact Heat Exchanger, Mohammed Al-Khateri

Theses

This study aims to investigate heat transfer in a miniaturized channel heat exchanger and effectiveness for given real-life design. The main objective of the study is to develop and build a high-performance heat exchanger for thermal management in automotive application using typical radiator manufacturing techniques. This research uses experimental and model-based investigation. It conceptualizes the Miniaturized Channel Heat Exchangers (MCHX) model-based study for demonstrating the design of miniaturized channel heat exchangers, manufacture, and study the heat exchanger effectiveness by validating the developed mathematical model experimentally. The proposed design of the MCHX is to use extruded tubes containing miniaturized channels as …

Thermal Boundary Condition Effects On Local Supercritical Co2 Heat Transfer Trends In Tubes, Nicholas C. Lopes

Doctoral Dissertations and Master's Theses

Supercritical carbon dioxide (sCO2) is a promising heat transfer fluid for the refrigeration and power generation industries due to its unique thermal properties and low environmental impact. To understand it as an alternative to traditional working fluids, the thermophysical and heat transfer phenomena of sCO2 are often studied using simplified geometries (tubes). Focus has been placed on investigating averaged heat transfer trends under an array of flow conditions with either a constant wall heat flux, constant wall temperature, or conjugate thermal boundary condition. Less emphasis has been placed on studying local sCO2 heat transfer developments. Tubular sCO2 numerical models that …

Non-Intrusive Reduced Order Model Formulation For Inverse Shape Design Including Deforming Meshes And Multiphysics Problems., Kapil Aryal

Mechanical and Aerospace Engineering Dissertations - Archive

Despite significant advancements in computer capabilities for numerical simulations, engineers continue to face limitations when dealing with large-scale full-order model(FOM) simulations. These simulations often necessitate repeated solves, such as those encountered in inverse design, real-time solution prediction, error quantification, and solver convergence, among others. To address these challenges, reduced order modeling (ROM) has emerged as a valuable approach. This thesis focuses on the development of an ROM framework that combines Proper Orthogonal Decomposition (POD) with machine learning techniques. This integrated approach is applied to a diverse range of heat transfer and fluid flow inverse design problems. POD constructs optimal sets …

Experimental Study On Thermal Performance Of Metal Foam Heat Sinks In Single Phase Liquid Immersion Cooling, Manish Kumawat

Mechanical and Aerospace Engineering Theses - Archive

In 1965, Intel co-founder Gordon Moore made the observation that the transistor counts on a chip double with a frequency of approximately every two years. This development resulted in more compact and potent ICs. However, the amount of heat produced on a chip increased proportionally with the number of transistors. Later, in the early 2000s, Dennard Scaling broke down. Transistors became so small that leakage currents (unwanted currents that flow within the transistor) emerged as a significant issue, and they contributed substantially to power consumption and heat generation. These tightly packed transistors produced heat, which decreased their performance and shortened …

Investigation Of The Effect Of Corundum Layer On The Heat Transfer Of Sic Slab, Sri Elsa Fatmi, Donanta Dhaneswara, Muhammad Anis, Ahmad Ashari

Journal of Materials Exploration and Findings

Aluminum is the most widely used metal in industry. Aluminum smelting is one of the important steps that needs to be carried out to produce products made of aluminum metal with good quality. In the process of smelting aluminum there are several problems that occur, one of which is the growth of corundum in Si C refractories which affects the quality of aluminum melt and the durability of Si C refractories. This research was conducted to see the heat transfer in Si C and the effect of the presence of Corundum on heat transfer. This research was carried out by …

The Deflection And Heat Transfer Analysis Of Injection Mold Cavity With Sla Cooling Channel Insert, Olumide Temidayo Aladesiun

Theses and Dissertations

Fast cooling in injection molding is the critical in the process economy. Among many different cooling channel designs available, conformal cooling offers the best and the most efficient cooling. However, limited awareness, accessibility, complexity, cost, knowledge, and experience limit the use of conformal cooling channels to be used into the mold in a molding process.

Typically, SLM(Selective Laser Melting) method is used to create cavity inserts with conformal cooling channels, however, due to the difficulties listed above, applications of conformal cooling channels are very limited. For an inexpensive alternative SLA (Stereolithography Apparatus) can print cavity inserts with conformal cooling channels. …

Measurement Of Low-Speed Impinging Jet Structure Using Temperature Sensitive Paint, Arthur Dean Woodworth

Masters Theses

Temperature sensitive paint (TSP) is used to analyze surface flow structures driven by a jet impinging on a heated steel sheet. Temperature and Nusselt number images are calculated from CCD images of the TSP surface. TSP calibration is discussed. Skin friction data is obtained from the temperature images.

Data is collected for metal and 3D-printed plastic nozzles of varying shape and size at one or two jet airspeeds depending on the nozzle. For the circular nozzles, data is collected for four Reynolds numbers at impinging angles of 90, 70, and 50 degrees. For the elliptical nozzles and the star-shaped nozzle, …

Biomass Characterization And Insulation Optimization Studies, Hussein Awad Kurdi Saad

Doctoral Dissertations and Master's Theses

This study indicates how biomass materials can be effectively used as naturally sustainable alternatives to insulation materials. Barley grains and oak leaves, straw, and jute are collected, and crushed into powders/ chopped pieces. The physical characteristics are measured to characterize each powder. The biomass powder reinforced composites are manufactured in varying weight ratios. The density and thermal conductivity of composite materials are measured. The properties of composites compared to those of commercial insulation materials are found to be close to them. Furthermore, genetic algorithms (GA) can be used to achieve multi-objective optimization entailing maximizing insulation (minimizing heat transfer) and simultaneously …

Comprehensive Review Of Heat Transfer Correlations Of Supercritical Co2 In Straight Tubes Near The Critical Point: A Historical Perspective, Nicholas C. Lopes, Yang Chao, Vinusha Dasarla, Neil P. Sullivan, Mark Ricklick, Sandra Boetcher

Publications

An exhaustive review was undertaken to assemble all available correlations for supercritical CO2 in straight, round tubes of any orientation with special attention paid to how the wildly varying fluid properties near the critical point are handled. The assemblage of correlations, and subsequent discussion, is presented from a historical perspective, starting from pioneering work on the topic in the 1950s to the modern day. Despite the growing sophistication of sCO2 heat transfer correlations, modern correlations are still only generally applicable over a relatively small range of operating conditions, and there has not been a substantial increase in predictive capabilities. Recently, …

Flow And Thermal Transport In Additively Manufactured Metal Lattices Based On Novel Unit-Cell Topologies, Inderjot Kaur

Theses and Dissertations

The emergence of metal Additive Manufacturing (AM) over the last two decades has opened venues to mitigate the challenges associated with stochastic open-cell metal foams manufactured through the traditional foaming process. Regular lattices with user-defined unit cell topologies have been reported to exhibit better mechanical properties in comparison to metal foams which extend their applicability to multifunctional heat exchangers subjected to both thermal and mechanical loads. The current study aims at investigating the thermal-hydraulic characteristics of promising novel unit cell topologies realizable through AM technologies. Experimental investigation was conducted on four different topologies, viz (a) Octet, (b) Face-diagonal (FD) cube, …

Development And Applications Of A Sensor For Measurement Of Different Modes Of Heat Transfer On Foods In A Residential Oven., Kervins Petit-Bois

Electronic Theses and Dissertations

Thermal characterization of an oven is an important part of designing an oven. Understanding how changes in cooking algorithm, oven construction, and oven materials affect cooking performance is critical in ensuring that an oven is properly designed. Often temperature data is used to characterize oven behavior, but this neglects the mode of heat transfer used to achieve these temperatures. Several studies have compared the different modes of heat transfer and cooking performance and have shown that cooking performance in radiation dominated modes are different than in convection dominated modes. The goal of this study is to develop a heat flux …