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open access

Radial and Axial Designs for Magnetic Absorbent Collector in Water

Description: The use of collection systems for magnetic sorbents such as Magnetic Activated Carbon are discussed in order to gauge their efficacy in marine environments. Two collectors were built and tested, one which utilized a radial orientation of magnets and another with axially placed magnets. The two systems underwent a series of test with differing linear velocities and angular velocities. From the results, the axial system outperformed its radial counterpart, being most effective with a relatively h… more
Date: August 2020
Creator: Renzetti, Andrew John
Partner: UNT Libraries
open access

Design Optimization of Functionalized Silica-Polymer Nanocomposite through Finite Element and Molecular Dynamics Modeling

Description: This dissertation focuses on studying membrane air dehumidification for a membrane moisture exchanger in a membrane heat pump system. The study has two parts: an optimization of membrane moisture exchanger for air dehumidification in the macroscale, and diffusion of water vapor in polymer nanocomposites membrane for humid air dehumidification in the nanoscale. In the first part of the research, the mass transport of water vapor molecules through hydrophilic silica nanochannel chains in hydropho… more
Date: August 2020
Creator: Almahmoud, Omar H. M.
Partner: UNT Libraries
open access

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

Description: 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
Partner: UNT Libraries
open access

The Role of Interface in Crystal Growth, Energy Harvesting and Storage Applications

Description: A flexible nanofibrous PVDF-BaTiO3 composite material is prepared for impact sensing and biomechanical energy harvesting applications. Dielectric polyvinylidene fluoride (PVDF) and barium titanate (BaTiO3)-PVDF nanofibrous composites were made using the electrospinning process based on a design of experiments approach. The ultrasonication process was optimized using a 2k factorial DoE approach to disperse BaTiO3 particles in PVDF solution in DMF. Scanning electron microscopy was used to charact… more
Date: December 2020
Creator: Ramesh, Dinesh
Partner: UNT Libraries
open access

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

Description: 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
Partner: UNT Libraries
open access

An Evaluation of Long-Term Air Quality Trends in North Texas using Statistical and Machine Learning Techniques

Description: While ozone design values have decreased since 2000, the values measured in Denton Airport South (DEN), an exurban region in the northwest tip of the Dallas-Fort Worth (DFW) metroplex, remains above those measured in Dallas Hinton (DAL) and Fort Worth Northwest (FWNW), two extremely urbanized regions; in addition, all three sites remained in nonattainment of National Ambient Air Quality Standards (NAAQS) ozone despite reductions in measured NOx and CO concentrations. The region's inability to a… more
Date: May 2020
Creator: Lim, Guo Quan
Partner: UNT Libraries

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

Description: 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
Partner: UNT Libraries

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

Description: 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
Partner: UNT Libraries
open access

Experimental Investigation on Efficiency of Fresnel Lenses with Different Manufacturing Methods

Description: Non-imaging Fresnel lenses have been playing an important role in improving the efficiency of the solar energy systems. Many researchers and scientists have devoted their research to optimize the design of the Fresnel lenses. Before it can contribute to energy efficiency increase, a Fresnel lens with optimized design will first need to be fabricated with the most cost-effective method as well as the best quality fabrication as possible. If targeted in a commercial market, feasibility of mass pr… more
Date: December 2020
Creator: Sexton, Ai Jiang
Partner: UNT Libraries

Thermal Transport Properties Enhancement of Phase Change Material by Using Boron Nitride Nanomaterials for Efficient Thermal Management

Description: In this research thermal properties enhancement of phase change material (PCM) using boron nitride nanomaterials such as nanoparticles and nanotubes is studied through experimental measurements, finite element method (FEM) through COMSOL 5.3 package and molecular dynamics simulations via equilibrium molecular dynamics simulation (EMD) with the Materials and Process Simulations (MAPS 4.3). This study includes two sections: thermal properties enhancement of inorganic salt hydrate (CaCl2∙6H2O) as … more
Date: December 2020
Creator: Barhemmati Rajab, Nastaran
Partner: UNT Libraries

Heat Transfer Analysis of a Small Thermochemical Reactor for Hydrogen Production from Ammonia

Description: Several types of research are ongoing throughout the world, to discover economical and reliable techniques to create hydrogen, and propagate the vision of a hydrogen economy. This research examines a COMSOL Multiphysics 5.4 heat transfer model for a hydrogen production system consisting of a retort with two different heat sources, namely a heat tape and an infrared (IR) lamp. The main objective was to compare the two heat sources and find out which one offers a better technique for producing hy… more
Date: August 2020
Creator: Owusu-Ansah, Nana
Partner: UNT Libraries
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