Language

Heat Transfer Analysis of Bio-Printed Tissue Mimicking Material Mixed with Silver Nanoparticles (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 a theoretical model to predict the surface temperature of microsphere. The heat conduction governing equation with Lambert law is numerically solved using COMSOL Multiphysics software. To validate the present simulation results, the experiments are conducted using a continuous laser system.
Date: August 2022
Creator: Chandrasegaran, Jedeshkeran
System: The UNT Digital Library

Development of an Enclosed Evaporation Chamber Utilizing a Fresnel Lens Solar Concentrator

This thesis project investigates the configuration of an enclosed evaporation chamber with the intention of converting seawater into potable freshwater. The evaporation chamber's sole heat source is provided by a Fresnel lens, located above the chamber, which concentrates sunlight onto a 3-inch diameter focal plate built into the core of the chamber. The design of the evaporation chamber is modeled after a solar still and is coupled with a heat exchanger to boost efficiency of the system. The chamber was designed with the objectives of being portable, lightweight, low cost, corrosion resistant, interchangeable, and size convenient with the goal of producing 1 Liter of freshwater per hour of operation. The evaporation chamber consists of two primary components, a core and an attached arrangement of fins, all of which are heated via the Fresnel lens. A consistent intake of 2 grams/second of saltwater enters from the top of the chamber and is then gravity fed across the fins. Fin orientation has been designed to inhibit the flow rate of water within the chamber, maximizing the surface area of contact with the heated fins. The evaporation chamber was modeled through SOLIDWORKS and underwent a physical optimization study to reduce material usage while …
Date: August 2022
Creator: Planz, Bridger T
System: The UNT Digital Library
Investigation of Structure-Property Effects on Nanoindentation and Small-Scale Mechanical Testing of Irradiated Additively Manufactured Stainless Steels (open access)

Investigation of Structure-Property Effects on Nanoindentation and Small-Scale Mechanical Testing of Irradiated Additively Manufactured Stainless Steels

Additively manufactured (AM) 316L and 17-4PH stainless steel parts, concretely made by laser powder bed fusion (L-PBF), are characterized and micro-mechanical properties of those steels are analyzed. This study also explored and extended to proton irradiation and small-scale mechanical testing of those materials, to investigate how irradiation affects microstructural evolution and thus mechanical properties at the surface level, which could be detrimental in the long term in nuclear applications. In-depth anisotropy analysis of L-PBF 316L stainless steel parts with the variations of volumetric energy density, a combined study of nanoindentation with EBSD (electron backscatter diffraction) mapping is shown to be an alternative methodology for enriching qualification protocols. Each grain with a different crystallographic orientation was mapped successfully by proper indentation properties. <122> and <111> oriented grains displayed higher than average indentation modulus and hardness whereas, <001>, <101>, and <210> oriented grains were found to be weaker in terms of indentation properties. Based on an extensive nanoindentation study, L-PBF 17-4 PH stainless steels are found to be very sensitive to high load rates and irradiation further escalates that sensitivity, especially after a 0.25 s-1 strain rate. 3D porosity measurement via X-ray microscope ensures L-PBF stainless steel parts are of more than …
Date: August 2022
Creator: Uddin, Mohammad Jashim
System: The UNT Digital Library
Development of an Interpolation-Free Sharp Interface Immersed Boundary Method for General CFD Simulations (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 and numerous modifications and refinements have been proposed and a number of variants of this approach now exist. In a nutshell, IB methods in the literature often suffer from numerical oscillations, implementation complexity, time-step restriction, burred interface, and lack of generality. This limits their ability to mimic conformal grid results and enforce Neumann boundary conditions. In addition, there is no generic IB capable of solving flow with multiple potentials, closely/loosely packed structures as well as IBs of infinitesimal thickness. This dissertation describes a novel 2$ ^{\text{nd}} $ order direct forcing immersed boundary method designed for simulation of two- and three-dimensional incompressible flow problems with complex immersed boundaries. In this formulation, each cell cut by the IB is reshaped to conform to the shape of the IB. IBs …
Date: August 2022
Creator: Kamau, Kingora
System: The UNT Digital Library
Artificial Neural Network Based Thermal Conductivity Prediction of Propylene Glycol Solutions with Real Time Heat Propagation Approach (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 propagation of a liquid from a laser pulse. The ANN can then be trained beforehand with simulated data and be tested in real time with temperature data from the MTS. This method could be applied to find the thermal conductivity of unknown fluids and biological samples, such as cells and tissues.
Date: August 2022
Creator: Jarrett, Andrew Caleb
System: The UNT Digital Library
Microgravity Vortex Phase Separator for Liquid Amine CO2 Removal System (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 flow rate. The subscale design for a VPS with a 3" inner diameter, 3.5" outer diameter, and 3.63" height removed a maximum of 84% of CO2 from a CO2 stream at 3.7 SCFH flow rate, 14°C temperature, and 82% RH, using 100 mL of 100% amine circulated at 1.52 LPM flow rate. The designed VPS also showed to be effective in removing relative humidity of the CO2 stream by up to 26% for the stated parameters. Regeneration of liquid amine in the VPS system is also proposed to allow for continuous CO2 removal. The results obtained in this work characterize the VPS system for CO2 removal in terms of various operating parameters for the gas (CO2) and liquid (liquid amine) phases, as well as provide initial insights …
Date: August 2022
Creator: Sarvadi, Alexander Armstrong
System: The UNT Digital Library

Design, Fabrication and Testing of a Novel Dual-Axis Automatic Solar Tracker System Using a Fresnel-Lens Solar Concentrator

This thesis project investigates, analyzes, designs, simulates, constructs and tests a dual-axis solar tracker system to track the sun and concentrates the heat of the sunlight, using a Fresnel lens, into a small area, which is above of an evaporator, to increase the temperature of the seawater to convert it into freshwater. The dual-axis solar tracker was designed with the main objectives that the structure was portable, dismountable, lightweight, low cost, corrosion resistant, wires inside pipes, accurate, small size, follow the sun automatically, off-grid (electrical), use green energy (solar powered), and has an empty area right below of the lens. First, a 500 mm diameter flat Fresnel lens was selected and simulated based on an algorithmic method achieved by a previous PhD student at UNT using MATLAB®, to give the optimization lens dimensions. The lens profile was drawn with AutoCAD®, then output profile lens was simulated in COMSOL Multiphysics®. The objective was to provide the high efficiency, optimum and high precision of the focal rays and heat to the receiver of the evaporator. A novel dual-axis solar tracker system was then designed that is portable, dismountable, lightweight and corrosion resistant. The solar tracker tracks the sun in two axis of …
Date: August 2021
Creator: Almara, Laura Mabel
System: The UNT Digital Library

Embedded Sensing Textiles for Corrosion Detection

Corrosion in underground and submerged steel pipes is a global problem. Coatings serve as an impermeable barrier or a sacrificial element to the transport of corrosive fluids. When this barrier fails, corrosion in the metal initiates. There is a critical need for sensors at the metal/coating interface as an early alert system. Current options utilize metal sensors, leading to accelerating corrosion. In this dissertation, a non-conductive sensor textile as a viable solution was investigated. For this purpose, non-woven zinc (II) oxide-polyvinylidene fluoride (ZnO-PVDF) nanocomposite fiber textiles were prepared in a range of weight fractions (1%, 3%, and 5% ZnO) and placed at the coating/steel interface. Electrochemical impedance spectroscopy (EIS) testing was performed during the immersion of the coated samples to validate the effectiveness of the sensor textile. In the second part of this dissertation, an accelerated thermal cyclic method has been applied to determine sensor's reliability in detecting corrosion under actual service condition. The results suggested that the coating is capable of detecting corrosion under harsh conditions. Moreover, the addition of ZnO decreases the error in sensor textile and improved coating's barrier property. In the next phase, experiments were conducted to detect the type of corrosion (pitting or uniform) underneath …
Date: August 2021
Creator: Chowdhury, Tonoy
System: The UNT Digital Library