Heat Transfer, Combustion Commons^™

Generative Designs Of Lightweight Air-Cooled Heat Exchangers, Connor Miller

Mechanical Engineering Undergraduate Honors Theses

The development of high-performance air-cooled heat exchangers is required to permit the rapid growth of vehicle and aircraft electrification. In electric vehicles and airliners, the motors and power electronics are integrated into a compact space, leading to unprecedently high power density. To achieve higher overall thermal efficiency, the heat exchangers must be extremely light while maintaining their heat transfer performance and mechanical robustness. Recently advances in 3D metal printing, e.g., direct metal laser sintering, and selective laser melting, have enabled the manufacturing of high-performance robust heat exchangers by eliminating thermal boundary resistance and ensuring a uniform thermal expansion coefficient. Nonetheless, …

Durability Of Non-Metallic Materials For Additively Manufactured Heat Spreader Fabrication, Rafael Estrella

Mechanical Engineering Undergraduate Honors Theses

Power electronics are necessary to convert power from DC sources for AC applications. As this technology trends toward smaller packaging for denser power loads, the increased electrical losses result in deleterious excess heat. Thermal management devices are required to prevent the effects of thermal runaway from shortening the longevity of these modules. Nonmetallic jet impingement heat spreaders provide several benefits in terms of weight and performance over conventional cold plates while not accentuating EMI from the switches in the power module; however, the polymer makeup of the materials previously used for fabricating these devices raises durability concerns under the high …

Triggering Thermal Runaway In Lithium-Ion Batteries, Chris John

Honors Scholar Theses

The proliferation of lithium-ion batteries enables electric devices such as cell phones to electric vehicles to become a reality. A latent danger, however, exists in these batteries. Mechanical, thermal, or electrical damage can initiate a phenomenon known as thermal runaway (TR). This damage causes internal short circuits within the battery, releasing heat and triggering exothermic decomposition reactions. The battery will catch fire if rapid cooling is not present. While experimental designs exist for evaluating TR, significant safety hazards and impracticality may impede testing efforts. Finite element analysis, therefore, becomes a vital tool in modeling TR and mitigation techniques. However, there …

Novel Thermal Coating For High-Speed Airplanes, Abinash Satapathy, Lakshay Battu, Liam Watson, Nazanin Rajabi

Symposium of Student Scholars

In comparison to various other materials, Carbon Fiber, specifically Carbon Fiber Reinforced Polymers (CFRP), is pre-eminent amongst other materials for use on aeronautical systems. Due to its high specific strength (strength-to-weight ratio), CFRP is prominent for carrying heavy loads while maintaining a lightweight build. However, when influenced by heat resulting from air resistance, CFRP is known to undergo serious degradation that would significantly decrease the effectiveness of the polymers. To prevent this degradation and maintain the strength of the CFRP, thermal protective layers (TPLs) are designed to shield the CFRP from heat exposure. This research is focused on the examination …

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 …

Investigation Of The Low-Temperature Combustion Phenomena Of A Fischer-Tropsch Synthetic Aerospace Fuel In A Constant Volume Combustion Chamber For Greenhouse Gas Reduction, Lily H. Parker

Honors College Theses

Greenhouse gases (GHG) have a harmful effect on our environment as they trap heat in the atmosphere accelerating climate change. As such, the Federal Aviation Administration’s 2025 strategic plan to reduce GHG emissions from air transportation. This call to action for a more environmentally friendly option highlights the importance of synthetic fuels as they are more sustainable compared to traditional fossil fuels. An investigation was conducted into the thermal-physical properties of Synthetic Fischer-Tropsch (F-T) Sustainable Aviation Fuels (SAF) and the Low Temperature Combustion (LTC). LTC is composed of the Low Temperature Heat Release (LTHR) and Negative Temperature Coefficient (NTC) region, …

Data On The Validation To Determine The Material Thermal Properties Estimation Via A One-Dimensional Transient Convection Model, Lauren B. Tomanek, Daniel S. Stutts

Mechanical and Aerospace Engineering Faculty Research & Creative Works

These data were acquired to estimate the parameters of a closed form solution of a one-dimensional transient convection heat diffusion PDE. The purpose was to demonstrate that the model could be used to determine the thermal conductivity. The system was tested for a wide range of thermal conductivity, 15-400 W/mK, in order to verify that the method was applicable for various materials. The data reported here refer to the study in the research articles, “Material Thermal Properties Estimation Via a One-Dimensional Transient Convection Model” and “Influence of porosity on the thermal, electrical, and mechanical performance of selective laser melted stainless …

Monitoring Of State Transitions In Extreme Environment Application Materials Using Fiber Bragg Grating Sensors, Sabuj Khadka

Electronic Theses and Dissertations

By embedding both a single fiber Bragg grating (FBG) sensor and a thermocouple (TC) during the manufacturing for extreme environment applications of certain classes of materials such as metals and polymers, a novel in-situ approach was developed to precisely monitor their entire manufacturing processes. This novel monitoring technique was able to identify many characteristic points during the curing of room and high-temperature epoxies and the solidification processes of metal alloys composed of tin and bismuth which were selected in this research purely for verification purposes. Some of the characteristic points identified for the epoxies were: (i) the gel point, (ii) …

Jcati Carbon Fiber Recycler: Oven Enclosure, Margarita Romero

All Undergraduate Projects

Central Washington University partners with Boeing and is funded by the Joint Center of Aerospace Technology Innovation (JCATI) to develop a mechanism that takes carbon fiber wing trimmings from Boeing that are resin coated and recycles carbon fiber. This is done by crushing the wing trimmings and then putting it into a 500°C oven to melt off the resin. This project focuses on the enclosure for the oven and making sure precautions are met such as having the outside surface be less than 45c through heat transfer analysis, argon fills enclosure in 13 minutes through fluid dynamics analysis, and 99% …

Experimental And Computational Heat Transfer Study Of Sco2 Single Jet Impingement, John Richardson

Electronic Theses and Dissertations, 2020-2023

The present study experimentally investigates the heat transfer capability of supercritical carbon dioxide (sCO2) single-jet impingement. The evaluated jet Reynolds number range is between 80,000 and 1,000,000, with a non-dimensional jet-to-target surface spacing of 2.8. CO2-impinging jet stagnation conditions were maintained at approximately 20 MPa and a temperature of 673 K for most experiments. The goal is to understand how changes in the aforementioned parameters influence heat transfer between the working fluid and the heated surface. Additionally, due to the elevated Reynolds numbers and difference in thermodynamic properties between air and CO2, air-derived impingement correlations may not be appropriate for …

Analytical Modeling Of A Novel Elastohydrodynamic Seal Design For Supercritical Co2 Power Cycles, Ikenna C. Ejiogu

College of Graduate Studies: Theses & Dissertations

Supercritical carbon dioxide (sCO₂) power cycles show great potential for higher plant efficiencies and power densities for a wide range of power generation applications such as fossil fuel power plants, nuclear power production, solar power, and geothermal power generation. sCO₂ leakage has been one of the main concerns in such applications, penalizing the cycle efficiencies. The effect of the seal leakage on the cycle efficiency could be as high as 0.65% for a utility sCO₂ power cycle. Therefore, there is a pressing need for effective sealing solutions to get the full benefit of sCO₂ power …

Heat Transfer Characterization Of Carbon Dioxide In Micro Impinging Jet(S) Near Critical Conditions, Stephen Adeoye

Electronic Theses and Dissertations, 2020-2023

The continuous growth and demand of increased operating performances of electronics has brought about an increase in the chip power density posing threat to the thermal management of these devices. Although numerous thermal solutions ranging from passive to active cooling together with a variety of working fluids have been adopted, however, the question whether these available cooling methods could meet up with the ever-growing need for increased operating performances is a concerning one. Jet impingement cooling has been effectively used in many industrial applications due to its high heat transfer capability. The limited study at the micro scale suggests that …

Numerical Study Of Flow Of Supercritical Carbon Dioxide Inside Microchannels With Heat Transfer, Uday Manda

Electronic Theses and Dissertations, 2020-2023

Heat transfer inside microscale geometries is a complex and a challenging phenomenon. As supercritical fluids display large variations in their properties in the vicinity of the critical point, their usage could be more beneficial than traditional coolants. This numerical study, in two parts, primarily focuses on the physics that drives the enhanced heat transfer characteristics of carbon dioxide (CO2) near its critical state and in its supercritical state. In the first part of the study, the flow of supercritical Carbon Dioxide (sCO2) over a heated surface inside a microchannel of hydraulic diameter 0.3 mm was studied using three-dimensional computational fluid …

An Experimental Study Of Fuel Selection For A Gasoline Multi-Mode, Spark Ignited – Compression Ignition Engine, Zachary J. Stanchina

Dissertations, Master's Theses and Master's Reports

In this study of fuels of different reactivities and their performance in a low-temperature combustion (LTC) engine. The engine was a 2.2L CRDI engine code D4HB provided by industry partner Hyundai America Technical Center inc. (HATCI). The engine was instrumented with in-cylinder pressure sensors allowing for monitoring of the combustion process.

First, the engine was operated with standard US pump grade gasoline, Research Octane number (RON) 91 E10, to find initial operation conditions as well as control points of stable operation for daily checks on system conditions.

Tested were 8 different fuel blends, the four base blends were provided by …

Radiative Conductivity Estimation Using Direct Approach For Fibrous Materials, Mohammad Khaleel

Theses and Dissertations--Mechanical and Aerospace Engineering

During planetary entry, space vehicles encounter high loads of thermal energy which requires a thermal protection system. Ablative thermal protection systems are usually made out of fibrous materials that exhibit internal radiation. In order to model the internal radiation response of a thermal protection system one should obtain proper radiative properties as well as thermal properties. The objective of this work is to provide a method that solves for the solid/gas thermal conductivity. Which can be used in coupled detailed radiative analysis.

Keywords: radiative conductivity, fibrous materials, radiative transfer, thermal protection system, P1 approximation, Finite Volume method.

A Decoupled Engineering Methodology For Accurate Prediction Of Ablative Surface Boundary Conditions In Thermal Protection Systems, Justin Cooper

Theses and Dissertations--Mechanical and Aerospace Engineering

The main objective of the present work is to demonstrate a method for prediction of aerothermal environments in the engineering design of hypersonic vehicles as an alternative to the current heritage method. Flat plate and stagnation point boundary layer theory require multiple assumptions to establish the current engineering paradigm. Chief among these assumptions is the similarity between mass and heat transfer. Origins of these assumptions are demonstrated and their relationship to conservative engineering design is analyzed, as well as conditions where they possibly break down. An alternative approach for assessing aerothermal environments from the fluid domain is presented, which permits …

The Performance Response Of A Heat Pipe Evacuated Tube Solar Collector Using Mgo/Mwcnt Hybrid Nanofluid As A Working Fluid, Ahmed A. Abdel-Rehim, Shady Henein

Mechanical Engineering

Utilizing a hybrid nanofluid is a promising solution for enhancing the thermal performance of the solar collector in a sustainable manner. In the present work, the effect of using magnesium oxide/multi-walled carbon nanotubes (MgO/MWCNT) hybrid nanofluid on the thermal performance of the evacuated tube solar collector is experimentally investigated. Four different weight ratios of (80:20), (70:30), (60:40), and (50:50) are used for a hybrid of MgO with MWCNTs in a water base, respectively. The experiments are performed at a 0.02% particle concentration and at various volume flow rates ranging from 1 to 3 L/min. The results show an enhancement in …

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 …

A Review On Heat Flux Measurement Techniques In The Nano And Microscale, Miguel Moreno

Honors Program: Senior Projects (Public)

Heat Flux measurements represent an important step in obtaining an accurate heat transfer profile in many engineering problems. Sensors capable of measuring this quantity have been around for decades, however, the increasing focus in nano and microscale applications in the industry and academia demands more accurate and smaller devices. This paper reviews some of the methods used to develop heat flux meters targeted to nano and microscale, as well as some calibration processes for the same. A combination of Luminescence and non-luminescence methods for direct and indirect measurement of heat flux will be discussed. A glimpse of what the future …

Spray Deposition Of Sustainable Plant Based Graphene In Thermosetting Carbon Fiber Laminates For Mechanical, Thermal, And Electrical Properties, Daniel W. Mulqueen, Siavash Sattar, Thienan Le, Oleksandr G. Kravchenko

Mechanical & Aerospace Engineering Faculty Publications

Graphene has generated substantial interest as a filler due to its exceptional strength, flexibility, and conductivity but faces obstacles in supply and implementation. A renewable, plant-based graphene nanoparticle (pGNP) presents a more accessible filler with the same properties as mineral graphenes. In this study, we examine the effects of pGNP, which was sprayed on a carbon fiber/epoxy prepreg at loadings from 1.1 to 4.2 g/m². The study considered the mechanical, thermal, and electrical properties of pGNP-composite. An even particle dispersion was achieved using a spray application of pGNP in a water/alcohol suspension with the addition of surfactants and …