Heat Transfer, Combustion Commons^™

Hotspot Cooling Performance For Confined Jet Impingement Cooling, Tanvir Ahmed Chowdhury

Electronic Theses and Dissertations, 2020-2023

The current trend in microelectronics is to manufacture devices with increased computational powers and reduced size. These devices with increased power densities are consequently subject to extreme thermal loads. Thermal management of these power loads is extremely challenging. The presence of the hotspots can make this challenge even more difficult. Jet impingement cooling is one of the top candidates for removing such extreme heat fluxes in microelectronics. Jet impingement cooling can achieve heat transfer coefficients (HTCs) due to its normal incident flow-field and ability to thin the local thermal boundary layer in the stagnation region. This dissertation presents the hotspot …

A Combustion Model For Multi-Component Fuels Based On Relative Reactivity And Molecular Structure, Arash Jamali

Dissertations, Master's Theses and Master's Reports

A reliable multi-component surrogate fuel model needs to be able to represent both physical properties and chemical kinetics of a real fuel. However, enhancing the fidelity of a model with detailed description of physical and chemical behavior of all fuel components found in real fuels is limited by the prohibitive computational load to calculate the combustion chemistry of the fuel. Hence, it is desirable to achieve computational efficiency by reducing the number of chemical surrogates at the minimum expense of prediction accuracy. The objective of this work is to develop a model that can simulate the oxidation of multi-component fuels …

Kinetics Of Elementary Reactions In Graphene Oxidation And Kinetics Of Oh* In Hydrogen Flames, Siamak Mahmoudi

Theses and Dissertations--Mechanical and Aerospace Engineering

Due to diverse applications of graphene, a kinetic mechanism describing rates of elementary reactions is extremely useful. To achieve that goal the elementary reactions need to be detected and their rates need to be determined. In this work the objectives are to use first-principle tools to find those reactions and analyze their paths in the context of graphene oxidation. Density functional theory (DFT) calculations provide the best approximation to the Schr\"{o}dinger equation, which is not feasible to solve analytically for large molecules like graphene. We have performed these calculations to find stable configurations (geometry optimization) and minimum energy paths between …

The Role Of Live Conifer Fuels In Crown Fires Spread, Adnan Darwish Ahmad

Theses and Dissertations--Mechanical and Aerospace Engineering

Live foliage for some tree and shrub species can support flaming fire spread at much higher moisture content than dead fuel materials. However, the role of live fuels in forest fires has been controversial in the past decades. Although ignition and spread statistical data for live and dead fuels exist in the literature, a clear understanding of the fundamental difference in the burning behavior is missing. To illuminate the role of live fuel on forest fire spreading, a laboratory ignition experiment was designed to examine the burning behavior of live Norway spruce needles. A schlieren-Infrared combined measurement apparatus was developed …

Evaluation Of Radiative Conductivity Inside A Porous Media With The Effect Of Participating Medium Based On Microscale Imaging, Mingping Zheng

Theses and Dissertations--Mechanical and Aerospace Engineering

Space vehicles will experience high loads of heat while entering the planetary atmosphere. At such high temperature, radiation becomes the dominant mode of heat transfer. Since the atmospheric entry environment is nearly impossible to duplicate in a laboratory environment, a numerical model to evaluate thermal performance of the thermal protection system was established. The model simulates the radiative heat transfer process in highly porous media, and the process also takes into account the influence of the participating media. An iterative approach and periodic boundary conditions are used to solve The unbalanced heat flux problem. CT scanned microscale Fiberform and artificial …

Waste Heat Recovery Of Industrial Regenerative Thermal Oxidizer (Rto), A Case Study, James Trimpe Jr.

Theses and Dissertations--Mechanical and Aerospace Engineering

Industrial processes that utilize and release hazardous compounds into the atmosphere are required to break down those compounds before exhausting them from their facilities. An industry-recognized method to break down those hazardous compounds is through thermal oxidation. Thermal oxidation is a process where the compounds are exposed to their auto-ignition temperature in an oxygen-rich environment and combust. The output of thermal oxidation is carbon dioxide, water vapor, and heat. Thermal oxidizers are equipment that performs the thermal oxidation process. The heat output from thermal oxidizers is wasted if directly exhausted into the atmosphere. Regenerative thermal oxidizers (RTOs) use the waste …

Modeling Thin Layers In Material Response Solvers, Christen Setters

Theses and Dissertations--Mechanical and Aerospace Engineering

Thermal Protection Systems (TPS) are a necessary component for atmospheric entry. Most TPS contain thin layers of various materials such as ceramic coatings, pore sealers and bonding agents. When modeling TPS, these thin layers are often neglected due to the difference in scale between the TPS (centimeters) and the thin layers (micrometers). In this study, a volume-averaging flux-conservation method is implemented in the governing equations of a finite volume material response code. The model proposes the addition of a volume and area fraction coefficient which utilizes a weighted-averaging between the amount of thin layer and heat shield material in a …

Tensile Environment Chamber, Cameron Ngai, Trent Hamilton, Mitchell Carroll, Jack Molitor

Mechanical Engineering

This project created the heating system, cooling system, and control system for an environmental chamber for a tensile test machine in the Cal Poly Composites Lab. This chamber allows for students to test material properties under a variety of thermal conditions. This project was done in collaboration with a team working on the structural aspect of the chamber. While consumer environmental chambers are on the market, they often cost more than $50,000. Additionally, our chamber conforms to further size and weight constraints. Because of this constraint, many conventional techniques and components used for these chambers are not feasible for our …

Multiscale Investigation Of Dropwise Condensation On A Smooth Hydrophilic Surface, Shahab Bayani Ahangar

Dissertations, Master's Theses and Master's Reports

The objective of this work is to identify the fundamental mechanism of dropwise condensation on a smooth solid surface by probing the solid-vapor interface during phase-change to evaluate the existence and structure of the thin film and the initial nucleus that develop during condensation. In this work, an automated Surface Plasmon Resonance imaging (SPRi) instrument with the ability to perform imaging in intensity modulation and angular modulation is developed. The SPRi instrument is used to probe (in three dimensions) the adsorbed film that forms on the substrate during dropwise condensation. SPRi with a lateral resolution of ~ 4-10 μm, thickness …

Marangoni Propulsion Of Active Particles, Saeed Jafari Kang

Dissertations, Master's Theses and Master's Reports

We study the surfing motion of active particles located at a flat liquid-gas interface. The particles create and maintain a surface tension gradient by asymmetrically discharging a surface tension-reducing agent. We employ theory and numerical simulation to investigate the Marangoni propulsion of these active surfers. First, we use the reciprocal theorem to establish a relationship between the propulsion speed and the release of the active chemical. This theoretical relation is utilized to examine the effect of wall confinement and geometry on the Marangoni-driven motion of active particle when the inertial effects are negligible and when the transports of the released …

Entertainment 721, Mark Hendricks, Noah John, Jadon Vanyo, Chelsea Payne

Williams Honors College, Honors Research Projects

The goal of this project was to design a luxury, aesthetically pleasing entertainment system with a TV lift mechanism that could be remote controlled. The design would also include a cooling cabinet for gaming systems, a remote locking system, and additional storage. Using a morphological chart and weighted decision matrix for each subsystem key features were determined to be included in the design. Several performance benchmarks were determined to accomplish the team’s design. Almost every benchmark was successful in the build of the first prototype. Several heat calculations and FEA analyses were performed on the system to ensure the success …

Jominy Hardenability Tester Redesign, Dennis Kopacz, Shadoe Beatty, Thomas Benenati, Jared Mclean, Matthew Yokosuk

Williams Honors College, Honors Research Projects

Our project is Redesigning a Hardenability Tester. The goal of this project is to figure out how to incorporate an intensive quenching system to the current design from last years group. An intensive quench is a new system that is safer to harden steel and it hardens steel more effectively than other quenching processes. This will be achieved through testing the initial design to make sure it is able to run. After that as a group we will take this system through a design process to introduce a safe process of intensive quenching to the tester.

High Injection Pressure Impinging Diesel Spray Characteristics And Subsequent Soot Formation In Reacting Conditions, Zhihao Zhao

Dissertations, Master's Theses and Master's Reports

The spray impingement in diesel engines attracts the attention of engine researchers in recent decades as the physical size of the engine is reduced. Due to the spray impingement, the atomization, vaporizing and air-fuel mixing quality is altered compared to a free spray. For emission control, soot is one of the major particulate emissions from diesel combustion and its formation in an impinged spray is worthy to be investigated.

Firstly, to understand the impinged spray characteristics, the experiments for both non-vaporizing and reacting conditions were conducted in a constant volume combustion vessel. The impinged spray was captured by a high-speed …

Effect Of Heat Treatment On Microstructure And Hardness Of A Worn Rail Repaired Using Laser Powder Deposition, Ershad Mortazavian, Zhiyong Wang, Hualiang Teng

Mechanical Engineering Faculty Research

The frequent replacement of worn rails on tracks brings an immense economic burden on the railroad industry, and also causes significant interruptions to railroad operation. Restoration of worn rails via laser powder deposition (LPD) can considerably reduce the associated maintenance costs. This study was focused on the use of LPD to repair the worn profile of a standard U.S. rail. The microstructure of the 304L stainless steel deposits with a minimum hardness of 85 HRB was composed of austenite, δ-ferrite, and sigma. Micropores were dispersed throughout the deposit, and microcracks were found at the rail-deposition interface. The pearlitic rail substrate …

Design Of A Heat Exchanger For A Supercritical Co2 Turbine System, Kehinde Oluwatobi Adenuga

Graduate Theses, Dissertations, and Problem Reports (ETD)

This research aims at designing a shell and tube heat exchanger which will drive a turbine operated on supercritical CO₂. Hot gases from boiler (simulated using air) at 1500 K is introduced into the shell to heat up the supercritical CO₂ at 10 MPa flowing within tubes from 450 K to 1050 K. The design was done using selected shell and tube heat exchanger empirical equations at predefined boundary conditions. The effect of shell and tube diameter on other design parameters was examined. It was observed that the number of tubes, tube external and internal side surface …

Performance And Economical Analysis Of Different Insulating Materials Used To Reduce The Heat Load Of An Existing Residential Building, Radwa A. El-Awadly, Ahmed A. Abdel-Rehim

Mechanical Engineering

The energy consumption from the residential sector is an important element which has an impact on the total energy consumption in any country. The heating and air conditioning loads can be reduced through many means. Using thermal insulation in buildings does not only contribute in reducing the required air conditioning system size, but also in reducing the annual energy cost for the whole building. In this case, the energy saving varies according to the building type, the climatic conditions at which the building is located as well as the type of the insulating material used. In the present study, an …

Numerical Investigation Of The Thermal Performance Of An Axially Rotating Internally Finned Receiver Tube Of A Parabolic Trough Concentrator, Andrew S. Tanious,, Ahmed A. Abdel-Rehim

Mechanical Engineering

Enhancement of the thermal performance of the parabolic trough receiver tube is one of the approaches to energy sustainability. In the present work, the thermal performance of an axially rotating receiver tube equipped with internal flat longitudinal fins is studied. The effects of both the fin height and the rate of axial rotation are investigated at low values of axial Reynold’s number. The numerical analysis is held at various rotation rates using ANSYS Fluent. The numerical findings showed that the effect of the axial rotation on the internally finned receiver tube is not significant yet negative where a maximum reduction …

Development Of Thermal Management Strategies Using Cylinder Deactivation For Low-Load Operation In Heavy-Duty Diesel Trucks, Christian M. Hushion

Graduate Theses, Dissertations, and Problem Reports (ETD)

Cylinder deactivation (CDA) has been used in gasoline engines, for decades, as a strategy for fuel consumption reduction. The idea of CDA in the heavy-duty diesel (HDD) engine sector has gained traction as a pathway to fuel efficient thermal management strategy. Oxides of nitrogen (NOx) control has been a major focus over the last decade and maintaining conducive aftertreatment temperatures is a major design aspect. HDD original equipment manufacturers (OEM) have developed a variety of thermal management strategies which almost all revolve around large fuel penalties. The goal of all of these strategies is for thermal management of the diesel …

Investigating Nox Vs Co2 Tradeoff In Heavy Duty Emissions Through The Years Under The Scope Of Carb’S 3-Bin Moving Average Window Method, Ghadi Sadek

Graduate Theses, Dissertations, and Problem Reports (ETD)

With the rise in urban pollution level over the last few years, regulatory agencies around the world have taken multiple steps to ensure engine exhaust pollutant are well monitored and properly regulated. Yet there exists a significant difference in emissions rates in various operating conditions between US and European products which currently uses a Moving average window (MAW) approach for their in-use compliance testing and certification program. Using WVU’s vehicle data collected using PEMS devices, this study aims at investigating the NOx versus CO2 tradeoff found in heavy duty diesel engines equipped with different aftertreatment technologies, under the scope of …

Torrefaction Of Mixed Solid Waste, Zhuo Xu

Dissertations, Master's Theses and Master's Reports

The world is witnessing unprecedented accumulation of solid wastes in the environment and landfills with well-documented ecological, environmental, health, and economic consequences. With population growth and rise in living standards, solid wastes generation will increase, making the issue more pressing. In addition, current practices of solid waste disposal are creating an immediate challenge and a long-term disaster-scale problem. The solid wastes comprises two main groups of materials: (i) fiber wastes (paper, food, wood, trimming, 61% of U.S. municipal solid waste) and (ii)uniquely challenging subset of plastic wastes (13%) that become a threat to global sustainability including dangers to marine and …