42 Matching Results

Search Results

Advanced search parameters have been applied.

in subjects: "Engineering, Mechanical"

Structural Design and Its Impact on Thermal Efficiency and Corrosion of All-Aluminum Microchannel Heat Exchangers

In this study, high-fidelity conjugate heat transfer simulations are used to model a micro-channel heat exchanger (MCHE) in a crossflow to study its thermal-hydraulic performance. This study considers three different microchannels (internal flow) geometries (circular, triangular, and square) with louver-shaped fins. The local flow field showed a strong coupling between the microchannel flow, solid domain, and crossflow. The flow separation and wake regions formed near MCHE resulted in a large v… more

This item is restricted from view until February 1, 2024.

Date: July 2023

Creator: Ahmed, Hossain

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Carbon Capture Utilization for Bio-Based Building Insulation Foams

Ecological, health and environmental concerns are driving the need for bio-resourced foams for the building industry and for other applications. This is because insulation is one of the most important aspects of the building envelope. Global building insulation is expected to reach USD 27.74 billion in 2022. Conventional insulation materials currently used in buildings are made from nonrenewable products (petroleum, fiber glass). However, they yield increasing unrecyclable eco-unfriendly waste … more

Date: August 2021

Creator: Oluwabunmi, Kayode Emmanuel

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Structural, Thermal, and Corrosion Properties of a Cold-Formed Steel Rigid Wall Relocatable Shelter

A prototype rigid wall relocatable shelter was designed and constructed using cold-formed steel (CFS) construction techniques including shear walls with corrugated sheathings. The design of the shelter was to be mechanically sound with adequate thermal performance and resistance to corrosion. Modeling of structural shear walls was performed using ABAQUS and verified with experimental results. At the project's conclusion, a completed full-scale prototype shelter was constructed.

Date: May 2020

Creator: Rowen, Alexander David

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Real Time Gas Monitoring and Modeling on the Pyrolysis Process of Biomass

In order to better understand the changes occurring in the internal environment of the pyrolysis process a method of monitoring the internal environment in real time is the key objective of this study. To accomplish this objective four tasks were laid out in order to develop an effective way of monitoring the changes in gases present as pyrolysis is occurring as well as in material activation processing. For all processing the self-activation process was used which combines pyrolysis and ther… more

This item is restricted from view until January 1, 2024.

Date: December 2021

Creator: Smith, Lee Miller

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Optimization of Silica Nanocomposite Membranes for Air Dehumidification

This thesis is focused on understanding the correct method to simulate atomistic models to calculate coefficient of diffusion of water through the membrane. It also aims to fix the method previously used in molecular modelling in which the simulation results did not match the experimental results. These membranes will be used in air dehumidification systems. The four types of membranes namely, polyurethane, polyurethane with silica nano particles, polyurethane with silica nano particles and ami… more

Date: May 2022

Creator: Appaji, Tejas

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Knowledge Based System and Decision Making Methodologies in Materials Selection for Aircraft Cabin Metallic Structures

Materials selection processes have been the most important aspects in product design and development. Knowledge-based system (KBS) and some of the methodologies used in the materials selection for the design of aircraft cabin metallic structures are discussed. Overall aircraft weight reduction means substantially less fuel consumption. Part of the solution to this problem is to find a way to reduce overall weight of metallic structures inside the cabin. Among various methodologies of materials … more

Date: August 2016

Creator: Adhikari, Pashupati Raj

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Heat Transfer Analysis of Bio-Printed Tissue Mimicking Material Mixed with Silver Nanoparticles

Novel tissue mimicking materials have been developed for cancer treatment research. In the present research work, the tissue mimicking material is printed using 3D bioprinting technology. The nanoparticles are homogeneously mixed with tissue mimicking materials to enhance the heating capacity. The thermal conductivity of tissue mimicking materials is measured using a micropipette thermal sensor (MTS). Further, the optimal value is identified based on optimization technique and incorporated into… more

Date: August 2022

Creator: Chandrasegaran, Jedeshkeran

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Programmable Mechanical Metamaterials with Negative Poisson's Ratio and Negative Thermal Expansion

Programmable matter is a material whose properties can be programmed to achieve particular shapes or mechanical properties upon command. This is an essential technique that could one day lead to morphing aircraft and ground vehicles. Metamaterials are the rationally designed artificial materials whose properties are not observed in nature. Their properties are typically controlled by geometry rather than chemical compositions. Combining metamaterials with a programmable function will create… more

Date: December 2016

Creator: Heo, Hyeonu

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Cyclic Polarization of AA 3102 in Corrosive Electrolytes Containing Sodium Chloride and Ammonium Sulfate

Corrosion of all aluminum microchannel heat exchangers present a challenge in automotive and heating, ventilation, and air conditioning (HVAC) industries. Reproducibility of Salt Water Acetic Acid Test (SWAAT) has been questioned and a need to new corrosion tests with better reproducibility has risen. Cyclic polarization, that is an electrochemical test, was explored for its suitability for the assessment of AA 3102 tube material that is currently a popular aluminum alloy used in manufacturing… more

Date: December 2016

Creator: Dorreyatim, Mohammad

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Particle Image Velocimetry Sensitivity Analysis Using Automatic Differentiation

A particle image velocimetry (PIV) computer software is analyzed in this work by applying automatic differentiation on it. We create two artificial images that contained particles that where moved with a known velocity field over time. These artificial images were created with parameters that we would have on real PIV experiments. Then we applied a PIV software to find the velocity output vectors. As we mentioned before, we applied automatic differentiation through all the algorithm to track th… more

Date: December 2016

Creator: Grullon Varela, Rodolfo Antonio

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Refrigeration Insulation Using Phase Change Material Incorporated Polyurethane Foam for Energy Savings

Incorporating insulation material with phase change materials (PCMs) could help enhance the insulation capability for a refrigerator system. The phase change material can absorb or release large amount of latent heat of fusion depending on surrounding temperatures for efficient thermal management. This research focuses on how incorporating PCM to the conventional PU foam insulation affects the inside temperatures of the refrigerator system and in-turn helps in conserving energy by reducing the … more

Date: August 2020

Creator: Shaik, Sania

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Artificial Neural Network Based Thermal Conductivity Prediction of Propylene Glycol Solutions with Real Time Heat Propagation Approach

Machine learning is fast growing field as it can be applied to solve a large amount of problems. One large subsection of machine learning are artificial neural networks (ANN), these work on pattern recognition and can be trained with data sets of known solutions. The objective of this thesis is to discuss the creation of an ANN capable of classifying differences in propylene glycol concentrations, up to 10%. Utilizing a micro pipette thermal sensor (MTS) it is possible to measure the heat propa… more

Date: August 2022

Creator: Jarrett, Andrew Caleb

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Conceptual Framework for the Development of an Air Quality Monitoring Station in Denton, Texas

Denton, Texas consistently reaches ozone nonattainment levels. This has led to a large focus of air pollution monitoring efforts in the region, with long-range transport being explored as a key contributor. For this study, the University of North Texas Discovery Park campus was chosen as a prospective location for an extensive air quality monitoring station. Sixteen years of ozone and meteorological data for five state-run monitoring sites within a 25 mile radius, including the nearest Denton A… more

Date: August 2016

Creator: Boling, Robyn

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Aerodynamic Optimization of a 2D Airfoil for Rotary-Wing Aircraft at Mars Atmospheric Conditions

The interest toward Mars exploration has been considerably increasing due to also the successful deployment of the Perseverance rover and the continuous tests developed by SpaceX's launch vehicle, Starship. While the Mars 2020 mission is currently in progress, the first controlled flight on another planet have been proven in April 2021 with the vertical take-off and landing of the Ingenuity rotorcraft on Mars. In addition, the rotorcraft Dragonfly is expected to achieve the same endeavor in Tit… more

Date: December 2021

Creator: Saez, Aleandro Gabriel

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Feasibility Study of Consolidation by Direct Compaction and Friction Stir Processing of Commercially Pure Titanium Powder

Commercially pure titanium can take up to six months to successfully manufacture a six-inch in diameter ingot in which can be shipped to be melted and shaped into other useful components. The applications to the corrosion-resistant, light weight, strong metal are endless, yet so is the manufacturing processing time. At a cost of around $80 per pound of certain grades of titanium powder, the everyday consumer cannot afford to use titanium in the many ways it is beneficial simply because the numb… more

Date: August 2016

Creator: Nichols, Leannah Marie

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Micro-Pipette Thermal Sensor: A Unique Technique for Thermal Characterization of Microfluids, Microsphere, and Biological Cell

In this research work, an innovative method for measurement of thermal conductivity of a small volume of liquids, microsphere, and the single cancer cell is demonstrated using a micro-pipette thermal sensor (MPTS). The method is based on laser point heating thermometry (LPHT) and transient heat transfer. When a single pulse of a laser beam heats the sensor tip which is in contact with the surrounding liquids or microsphere/cells, the temperature change in the sensor is reliant on the thermal pr… more

Date: May 2020

Creator: Shrestha, Ramesh

Item Type: Thesis or Dissertation

Partner: UNT Libraries

Passive Control of Fiber Orientation in Direct Ink Writing 3D Printing

Several active methods, which requires external control systems and moving parts, have been developed to control the fiber orientation during 3D printing. Active mechanisms like rotating nozzle, impeller, and magnetic field have been integrated to realize complex internal fiber structures. In this study, instead of using active methods, I investigate a passive method for controlling the fiber orientation without any moving parts or additional mechatronics added in the printing process. Composit… more

Date: August 2020

Creator: Khatri, Nava Raj

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Microgravity Vortex Phase Separator for Liquid Amine CO2 Removal System

The present study investigates vortex phase separator (VPS) technology as a new approach for a liquid amine CO2 removal system. Experimental results obtained using a 99.99% pure CO2 stream and liquid amine with varying concentrations demonstrate the VPS' ability to decrease CO2 volume at its gas outlet. Operating parameters such as CO2 flow rate, relative humidity (RH), and temperature were systematically varied during experimental procedure, as well as working fluid temperature, volume, and fl… more

Date: August 2022

Creator: Sarvadi, Alexander Armstrong

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Multi-Fidelity Study of Aerodynamics and Aeroacoustics Characteristics of a Quadrotor Biplane Tailsitter

Recent advances in manufacturing and growing concerns on the sustainability of aviation environment have led to a remarkable interest in electrical unmanned aerial systems (UASs) in the past decade. Among various UAS types, the newly designed quadrotor biplane tailsitter class is capable of delivering a wide range of civilian and military tasks, relying on its Vertical Take-Off and Landing (VTOL) capability as well as great maneuverability. Nevertheless, as such UASs employ rotors to generate t… more

Date: May 2022

Creator: Heydari, Morteza

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Development of an Interpolation-Free Sharp Interface Immersed Boundary Method for General CFD Simulations

Immersed boundary (IB) methods are attractive due to their ability to simulate flow over complex geometries on a simple Cartesian mesh. Unlike conformal grid formulation, the mesh does not need to conform to the shape and orientation of the boundary. This eliminates the need for complex mesh and/or re-meshing in simulations with moving/morphing boundaries, which can be cumbersome and computationally expensive. However, the imposition of boundary conditions in IB methods is not straightforward … more

Date: August 2022

Creator: Kamau, Kingora

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Modeling of Fracture Toughness of Magnesium Alloy WE43 Before and After Friction Stir Processing

Magnesium alloys are a popular research topic for structural applications because they have a lower density than conventional structural materials, including steel, titanium, and aluminum; however, the reliability and safety of their mechanical properties must be further proven. An important mechanical property for this purpose is fracture toughness, which is the measure of the material's resistance to crack propagation. In this study, a model of an experiment to investigate the fracture toughn… more

Date: December 2016

Creator: Lipscomb, Celena Andrea

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Topology and Lattice-Based Structural Design Optimization for Additively Manufactured Medical Implants

Topology-based optimization techniques and lattice structures are powerful ways to accomplish lightweight components with enhanced mechanical performance. Recent developments in additive manufacturing (AM) have led the way to extraordinary opportunities in realizing complex designs that are derived from topology and lattice-based structural optimization. The main aim of this work is to give a contribution, in the integration between structural optimization techniques and AM, by proposing a setu… more

Date: May 2019

Creator: Peto, Marinela

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Thermal Transport Modeling in Three-Dimensional Pillared-Graphene Structures for Efficient Heat Removal

Pillared-graphene structure (PGS) is a novel three-dimensional structure consists of parallel graphene sheets that are separated by carbon nanotube (CNT) pillars that is proposed for efficient thermal management of electronics. For microscale simulations, finite element analyses were carried out by imposing a heat flux on several PGS configurations using a Gaussian pulse. The temperature gradient and distribution in the structures was evaluated to determine the optimum design for heat transfer.… more

Date: December 2020

Creator: Almahmoud, Khaled Hasan Musa

Item Type: Thesis or Dissertation

Partner: UNT Libraries

open access

Angular Analysis of a Wide-Band Energy Harvester based on Mutually Perpendicular Vibrating Piezoelectric Beams

The recent advancements in electronics and the advents of small scaled instruments has increased the attachment of life and functionality of devices to electrical power sources but at the same time granted the engineers and companies the ability to use smaller sources of power and batteries. Therefore, many scientists have tried to come up with new solutions for a power alternatives. Piezoelectric is a promising material which can readily produce continuous electric power from mechanical inputs… more

Date: December 2016

Creator: Mirzaabedini, Sohrab

Item Type: Thesis or Dissertation

Partner: UNT Libraries