+publisher:"Virginia Tech" +contributor:("Ellis, Michael W.")

Virginia Tech

1. Alshawaf, Hussain M J A A M A. A Novel Thermal Method for Pipe Flow Measurements Using a Non-invasive BTU Meter.

Degree: MS, Mechanical Engineering, 2018, Virginia Tech

► This work presents the development of a novel and non-invasive method that measures fluid flow rate and temperature in pipes. While current non-invasive flow meters… (more)

▼ This work presents the development of a novel and non-invasive method that measures fluid flow rate and temperature in pipes. While current non-invasive flow meters are able to measure pipe flow rate, they cannot simultaneously measure the internal temperature of the fluid flow, which limits their widespread application. Moreover, devices that are able to determine flow temperature are primarily intrusive and require constant maintenance, which can shut down operation, resulting in downtime and economic loss. Consequently, non-invasive flow rate and temperature measurement systems are becoming increasingly attractive for a variety of operations, including for use in leak detection, energy metering, energy optimization, and oil and gas production, to name a few. In this work, a new solution method and parameter estimation scheme are developed and deployed to non-invasively determine fluid flow rate and temperature in a pipe. This new method is utilized in conjunction with a sensor-based apparatus – "namely, the Combined Heat Flux and Temperature Sensor (CHFT+), which employs simultaneous heat flux and temperature measurements for non-invasive thermal interrogation (NITI). In this work, the CHFT+ sensor embodiment is referred to as the British Thermal Unit (BTU) Meter. The fluid's flow rate and temperature are determined by estimating the fluid's convection heat transfer coefficient and the sensor-pipe thermal contact resistance. The new solution method and parameter estimation scheme were validated using both simulated and experimental data. The experimental data was validated for accuracy using a commercially available FR1118P10 Inline Flowmeter by Sotera Systems (Fort Wayne, IN) and a ThermaGate sensor by ThermaSENSE Corp. (Roanoke, VA). This study's experimental results displayed excellent agreement with values estimated from the aforementioned methods. Once tested in conjunction with the non-invasive BTU Meter, the proposed solution and parameter estimation scheme displayed an excellent level of validity and reliability in the results. Given the proposed BTU Meter's non-invasive design and experimental results, the developed solution and parameter estimation scheme shows promise for use in a variety of different residential, commercial, and industrial applications. Advisors/Committee Members: Diller, Thomas E (committeechair), Wicks, Alfred L (committee member), Ellis, Michael W (committee member).

Subjects/Keywords: Pipe Flow Rate; Non-Invasive; Heat Flux; Fluid Temperature; Parameter Estimation; Convection Heat Transfer Coefficient; Thermal Contact Resistance; Energy Transfer; Non-Invasive Thermal Interrogation

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APA (6^th Edition):

Alshawaf, H. M. J. A. A. M. A. (2018). A Novel Thermal Method for Pipe Flow Measurements Using a Non-invasive BTU Meter. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/101528

Chicago Manual of Style (16^th Edition):

Alshawaf, Hussain M J A A M A. “A Novel Thermal Method for Pipe Flow Measurements Using a Non-invasive BTU Meter.” 2018. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/101528.

MLA Handbook (7^th Edition):

Alshawaf, Hussain M J A A M A. “A Novel Thermal Method for Pipe Flow Measurements Using a Non-invasive BTU Meter.” 2018. Web. 07 Mar 2021.

Vancouver:

Alshawaf HMJAAMA. A Novel Thermal Method for Pipe Flow Measurements Using a Non-invasive BTU Meter. [Internet] [Masters thesis]. Virginia Tech; 2018. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/101528.

Council of Science Editors:

Alshawaf HMJAAMA. A Novel Thermal Method for Pipe Flow Measurements Using a Non-invasive BTU Meter. [Masters Thesis]. Virginia Tech; 2018. Available from: http://hdl.handle.net/10919/101528

Virginia Tech

2. Anderson, Matthew John. Economic and Environmental Analysis of Cool Thermal Energy Storage as an Alternative to Batteries for the Integration of Intermittent Renewable Energy Sources.

Degree: MS, Mechanical Engineering, 2015, Virginia Tech

URL: http://hdl.handle.net/10919/51195

► The balance of the supply of renewable energy sources with electricity demand will become increasingly difficult with further penetration of renewable energy sources. Traditionally, large… (more)

Subjects/Keywords: Renewable Energy Balancing; Cool Thermal Energy Storage; Ice Harvester; Internal-Melt Ice-on-Coil; Stationary Lead-Acid Battery

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APA (6^th Edition):

Anderson, M. J. (2015). Economic and Environmental Analysis of Cool Thermal Energy Storage as an Alternative to Batteries for the Integration of Intermittent Renewable Energy Sources. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/51195

Chicago Manual of Style (16^th Edition):

Anderson, Matthew John. “Economic and Environmental Analysis of Cool Thermal Energy Storage as an Alternative to Batteries for the Integration of Intermittent Renewable Energy Sources.” 2015. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/51195.

MLA Handbook (7^th Edition):

Anderson, Matthew John. “Economic and Environmental Analysis of Cool Thermal Energy Storage as an Alternative to Batteries for the Integration of Intermittent Renewable Energy Sources.” 2015. Web. 07 Mar 2021.

Vancouver:

Anderson MJ. Economic and Environmental Analysis of Cool Thermal Energy Storage as an Alternative to Batteries for the Integration of Intermittent Renewable Energy Sources. [Internet] [Masters thesis]. Virginia Tech; 2015. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/51195.

Council of Science Editors:

Anderson MJ. Economic and Environmental Analysis of Cool Thermal Energy Storage as an Alternative to Batteries for the Integration of Intermittent Renewable Energy Sources. [Masters Thesis]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/51195

Virginia Tech

3. Cen, Yijia. Fog Harvesting: Inspired by Spider Silk.

Degree: MS, Mechanical Engineering, 2020, Virginia Tech

URL: http://hdl.handle.net/10919/96610

► Water shortage is one of the highest concerns all around the world and collecting fog water has drawn lots of attention recently. The focus of… (more)

▼ Water shortage is one of the highest concerns all around the world and collecting fog water has drawn lots of attention recently. The focus of this thesis is to increase the fog collection rate by using less hazardous, low maintenance and low-cost methods. Commonly used fog collector is a large vertical plastic mesh. However, those large meshes suffer from water pinning and easily evaporation issues. Water repellent chemicals have been studied and used to dissolve those issues, however, the chemical coating will not last long and it will contaminate the collected water easily. Moreover, coating the water repellent chemicals requires professional operation and maintenance. To solve this issue without using chemical coating, we have learned unique water collection and directional behavior from spider silk. In a humid day, you will easily find the spider web with fully covered water droplets in an organized order. If we zoom in on single spider silk, the spider silk is composed of many puff and joint regions. Those puff regions have higher water collection ability than the joint regions, and this puff region shrinks down to form the spindle-knot shape with angle β above the joint region. This unique spindle-knot structure induces the water directional movement, and three forces- surface tension force, pinning force, and Laplace pressure force – are controlling the moving direction. Chapter 1 shows equation derivations with surface material effects, surface roughness effects and water droplet landing location effects. To form such special spindle-knot structure, commonly used formation methods are fluid coating and dip coating by using an organic polymer solvent. However, commonly used organic polymer-solvent suffer from a high level of hazardous, resulting in high laboratory requirement and operation cost. In Chapter 2 of this thesis, that commonly used organic polymer-solvent will be replaced by water/ethanol mixture and light-sensitive materials to form the spindle-knots. Furthermore, the 3D printing method is adopted to build a spider web with spindle-knot structures. Advisors/Committee Members: Cheng, Jiangtao (committeechair), Ellis, Michael W. (committee member), Zheng, Xiaoyu (committee member).

Subjects/Keywords: Fog harvesting; spindle-knots; directional movement

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APA (6^th Edition):

Cen, Y. (2020). Fog Harvesting: Inspired by Spider Silk. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/96610

Chicago Manual of Style (16^th Edition):

Cen, Yijia. “Fog Harvesting: Inspired by Spider Silk.” 2020. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/96610.

MLA Handbook (7^th Edition):

Cen, Yijia. “Fog Harvesting: Inspired by Spider Silk.” 2020. Web. 07 Mar 2021.

Vancouver:

Cen Y. Fog Harvesting: Inspired by Spider Silk. [Internet] [Masters thesis]. Virginia Tech; 2020. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/96610.

Council of Science Editors:

Cen Y. Fog Harvesting: Inspired by Spider Silk. [Masters Thesis]. Virginia Tech; 2020. Available from: http://hdl.handle.net/10919/96610

Virginia Tech

4. Gantt, Lynn Rupert. Energy Losses for Propelling and Braking Conditions of an Electric Vehicle.

Degree: MS, Mechanical Engineering, 2011, Virginia Tech

URL: http://hdl.handle.net/10919/32879

► The market segment of hybrid-electric and full function electric vehicles is growing within the automotive transportation sector. While many papers exist concerning fuel economy or… (more)

▼ The market segment of hybrid-electric and full function electric vehicles is growing within the automotive transportation sector. While many papers exist concerning fuel economy or fuel consumption and the limitations of conventional powertrains, little published work is available for vehicles which use grid electricity as an energy source for propulsion. Generally, the emphasis is put solely on the average drive cycle efficiency for the vehicle with very little thought given to propelling and braking powertrain losses for individual components. The modeling section of this paper will take basic energy loss equations for vehicle speed and acceleration, along with component efficiency information to predict the grid energy consumption in AC Wh/km for a given drive cycle. This paper explains how to calculate the forces experienced by a vehicle while completing a drive cycle in three different ways: using vehicle characteristics, United States Environmental Protection Agencyâ s (EPA) Dynamometer â targetâ coefficients, and an adaptation of the Sovran parameters. Once the vehicle forces are determined, power and energy demands at the wheels are determined. The vehicle power demands are split into propelling, braking, and idle to aide in the understanding of what it takes to move a vehicle and to identify possible areas for improvement. Then, using component efficiency data for various parameters of interest, the energy consumption of the vehicle as a pure EV is supplied in both DC (at the battery terminals) and AC (from the electric grid) Wh/km. The energy that flows into and out of each component while the vehicle is driving along with the losses at each step along the way of the energy path are detailed and explained. The final goal is to make the results of the model match the vehicle for any driving schedule. Validation work is performed in order to take the model estimates for efficiencies and correlate them against real world data. By using the Virginia Tech Range Extended Crossover (VTREX) and collecting data from testing, the parameters that the model is based on will be correlated with real world test data. The paper presents a propelling, braking, and net energy weighted drive cycle averaged efficiency that can be used to calculate the losses for a given cycle. In understanding the losses at each component, not just the individual efficiency, areas for future vehicle improvement can be identified to reduce petroleum energy use and greenhouse gases. The electric range of the vehicle factors heavily into the Utility Weighted fuel economy of a plug-in hybrid electric vehicle, which will also be addressed. Advisors/Committee Members: Nelson, Douglas J. (committeechair), West, Robert L. Jr. (committee member), Ellis, Michael W. (committee member).

Subjects/Keywords: Extended Range Electric Vehicle; Hybrid Vehicles; Energy Flow; Powertrain Losses; Electric Vehicle; Modeling

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Gantt, L. R. (2011). Energy Losses for Propelling and Braking Conditions of an Electric Vehicle. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/32879

Chicago Manual of Style (16^th Edition):

Gantt, Lynn Rupert. “Energy Losses for Propelling and Braking Conditions of an Electric Vehicle.” 2011. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/32879.

MLA Handbook (7^th Edition):

Gantt, Lynn Rupert. “Energy Losses for Propelling and Braking Conditions of an Electric Vehicle.” 2011. Web. 07 Mar 2021.

Vancouver:

Gantt LR. Energy Losses for Propelling and Braking Conditions of an Electric Vehicle. [Internet] [Masters thesis]. Virginia Tech; 2011. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/32879.

Council of Science Editors:

Gantt LR. Energy Losses for Propelling and Braking Conditions of an Electric Vehicle. [Masters Thesis]. Virginia Tech; 2011. Available from: http://hdl.handle.net/10919/32879

Virginia Tech

5. Gvozdich, Grant Gregory. Modeling the Transient Effects of High Energy Subsystems on High-Performance Aerospace Systems.

Degree: MS, Mechanical Engineering, 2011, Virginia Tech

URL: http://hdl.handle.net/10919/35704

► As directed energy technology continues to evolve and become a viable weapon alternative, a need exists to investigate the impacts of these applications without a… (more)

▼ As directed energy technology continues to evolve and become a viable weapon alternative, a need exists to investigate the impacts of these applications without a â plug-and-checkâ method, but rather with an analysis governed by fundamental principles. This thesis examines the transient thermal loads that a high-energy weapon system introduces into a high performance aircraft using fundamental thermodynamic and heat transfer analyses. The high-energy weapon system employed in this research contains power storage, power conditioning equipment, optics, and a solid-state laser. The high-energy weapon system is integrated into the aircraft by a dedicated thermal management system connected to the onboard air and fuel fluid networks. The dedicated thermal management system includes heat exchangers, thermal storage, microchannel coolers, valves, and pumps. Governing equations for the electric directed energy weapon subsystem and thermal management system are formulated for each system component and modeled in Mathworkâ s SimulinkTM. System models are integrated into a generic, high-performance aircraft model created as part of the Air Force Research Laboratoryâ s Integrated Vehicle Energy Technology Demonstration (INVENT) program. The aircraft model performs a defined mission profile, firing the directed energy weapon during the high-altitude, transonic cruise segment. When firing a 100-kilowatt directed energy weapon system operating at 16.9% efficiency, large thermal transients quickly heat downstream onboard systems. Real-time heat rejection causes temperature spikes in avionic and environment systems that exceed allowable operation constraints. The addition of thermal storage to the thermal management system mitigates thermal impacts downstream of the directed energy weapon by delaying the time thermal loads are rejected to aircraft, thereby reducing peak and average loads. Although thermal storage is shown to mitigate peak loads in downstream onboard systems, thermal closure is yet to be achieved. This research presents a general and fundamental approach to investigating the thermal impacts of a directed energy weapon system on a high-performance aircraft. Although specific iii cases are analyzed, this general approach to model development and simulation is conducive to component and system customization for many other cases. Additionally, the supplementation of models with analytical, semi-empirical, and empirical data further tailors model development to each userâ s need while increasing the potential to enhance accuracy and efficacy. Without the material expenses of a â plug-and-checkâ method, component and system level modeling of the directed energy weapon system and high-performance aircraft provides valuable insight into the thermal responses of highly-coupled systems. Advisors/Committee Members: von Spakovsky, Michael R. (committeechair), O'Brien, Walter F. Jr. (committee member), Ellis, Michael W. (committee member).

Subjects/Keywords: aerospace; thermal storage; directed energy weapon; solid-state laser

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APA (6^th Edition):

Gvozdich, G. G. (2011). Modeling the Transient Effects of High Energy Subsystems on High-Performance Aerospace Systems. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/35704

Chicago Manual of Style (16^th Edition):

Gvozdich, Grant Gregory. “Modeling the Transient Effects of High Energy Subsystems on High-Performance Aerospace Systems.” 2011. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/35704.

MLA Handbook (7^th Edition):

Gvozdich, Grant Gregory. “Modeling the Transient Effects of High Energy Subsystems on High-Performance Aerospace Systems.” 2011. Web. 07 Mar 2021.

Vancouver:

Gvozdich GG. Modeling the Transient Effects of High Energy Subsystems on High-Performance Aerospace Systems. [Internet] [Masters thesis]. Virginia Tech; 2011. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/35704.

Council of Science Editors:

Gvozdich GG. Modeling the Transient Effects of High Energy Subsystems on High-Performance Aerospace Systems. [Masters Thesis]. Virginia Tech; 2011. Available from: http://hdl.handle.net/10919/35704

Virginia Tech

6. Tamaro, Courtney Alex. Vehicle powertrain model to predict energy consumption for ecorouting purposes.

Degree: MS, Mechanical Engineering, 2016, Virginia Tech

URL: http://hdl.handle.net/10919/71635

► The automotive industry is facing some of the most difficult design challenges in industry history. Developing innovative methods to reduce fossil fuel dependence is imperative… (more)

Subjects/Keywords: powertrain modeling; ecorouting; scalable powertrain components; fuel economy; energy consumption; hybrid electric vehicle; plug-in; battery electric vehicle; environment; greenhouse gases; petroleum

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APA (6^th Edition):

Tamaro, C. A. (2016). Vehicle powertrain model to predict energy consumption for ecorouting purposes. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/71635

Chicago Manual of Style (16^th Edition):

Tamaro, Courtney Alex. “Vehicle powertrain model to predict energy consumption for ecorouting purposes.” 2016. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/71635.

MLA Handbook (7^th Edition):

Tamaro, Courtney Alex. “Vehicle powertrain model to predict energy consumption for ecorouting purposes.” 2016. Web. 07 Mar 2021.

Vancouver:

Tamaro CA. Vehicle powertrain model to predict energy consumption for ecorouting purposes. [Internet] [Masters thesis]. Virginia Tech; 2016. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/71635.

Council of Science Editors:

Tamaro CA. Vehicle powertrain model to predict energy consumption for ecorouting purposes. [Masters Thesis]. Virginia Tech; 2016. Available from: http://hdl.handle.net/10919/71635

Virginia Tech

7. Gordon, Ashley Rebecca. Evaluation of TiO2 as a Pt-Catalyst Support in a Direct Ethanol Fuel Cell.

Degree: MS, Mechanical Engineering, 2012, Virginia Tech

URL: http://hdl.handle.net/10919/31505

► Direct ethanol fuel cells are of interest due to the high energy density, ease of distribution and handling, and low toxicity of ethanol. Difficulties lie… (more)

Subjects/Keywords: potentiostatic hold; power density; OCV; polarization curves; electrochemical analysis; cyclic voltammetry; ethanol oxidation

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APA (6^th Edition):

Gordon, A. R. (2012). Evaluation of TiO2 as a Pt-Catalyst Support in a Direct Ethanol Fuel Cell. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/31505

Chicago Manual of Style (16^th Edition):

Gordon, Ashley Rebecca. “Evaluation of TiO2 as a Pt-Catalyst Support in a Direct Ethanol Fuel Cell.” 2012. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/31505.

MLA Handbook (7^th Edition):

Gordon, Ashley Rebecca. “Evaluation of TiO2 as a Pt-Catalyst Support in a Direct Ethanol Fuel Cell.” 2012. Web. 07 Mar 2021.

Vancouver:

Gordon AR. Evaluation of TiO2 as a Pt-Catalyst Support in a Direct Ethanol Fuel Cell. [Internet] [Masters thesis]. Virginia Tech; 2012. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/31505.

Council of Science Editors:

Gordon AR. Evaluation of TiO2 as a Pt-Catalyst Support in a Direct Ethanol Fuel Cell. [Masters Thesis]. Virginia Tech; 2012. Available from: http://hdl.handle.net/10919/31505

Virginia Tech

8. Zheng, Panni. The Design and Optimization of a Lithium-ion Battery Direct Recycling Process.

Degree: MS, Mechanical Engineering, 2019, Virginia Tech

URL: http://hdl.handle.net/10919/93212

► Nowadays, Lithium-ion batteries (LIBs) have dominated the power source market in a variety of applications. A LIB contains an anode, a cathode and electrolyte. The… (more)

Subjects/Keywords: Battery recycling; Lithium Cobalt Oxide; Lithiation

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APA (6^th Edition):

Zheng, P. (2019). The Design and Optimization of a Lithium-ion Battery Direct Recycling Process. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/93212

Chicago Manual of Style (16^th Edition):

Zheng, Panni. “The Design and Optimization of a Lithium-ion Battery Direct Recycling Process.” 2019. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/93212.

MLA Handbook (7^th Edition):

Zheng, Panni. “The Design and Optimization of a Lithium-ion Battery Direct Recycling Process.” 2019. Web. 07 Mar 2021.

Vancouver:

Zheng P. The Design and Optimization of a Lithium-ion Battery Direct Recycling Process. [Internet] [Masters thesis]. Virginia Tech; 2019. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/93212.

Council of Science Editors:

Zheng P. The Design and Optimization of a Lithium-ion Battery Direct Recycling Process. [Masters Thesis]. Virginia Tech; 2019. Available from: http://hdl.handle.net/10919/93212

Virginia Tech

9. Regner, Keith Thomas. Combining In Situ Measurements and Advanced Catalyst Layer Modeling in PEM Fuel Cells.

Degree: MS, Mechanical Engineering, 2011, Virginia Tech

URL: http://hdl.handle.net/10919/34978

► Catalyst layer modeling can be a useful tool for fuel cell design. By comparing numerical results to experimental results, numerical models can provide a better… (more)

Subjects/Keywords: Measurement; DNS; Through-Plane Transport; Catalyst Layer; PEM Fuel Cell

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APA (6^th Edition):

Regner, K. T. (2011). Combining In Situ Measurements and Advanced Catalyst Layer Modeling in PEM Fuel Cells. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/34978

Chicago Manual of Style (16^th Edition):

Regner, Keith Thomas. “Combining In Situ Measurements and Advanced Catalyst Layer Modeling in PEM Fuel Cells.” 2011. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/34978.

MLA Handbook (7^th Edition):

Regner, Keith Thomas. “Combining In Situ Measurements and Advanced Catalyst Layer Modeling in PEM Fuel Cells.” 2011. Web. 07 Mar 2021.

Vancouver:

Regner KT. Combining In Situ Measurements and Advanced Catalyst Layer Modeling in PEM Fuel Cells. [Internet] [Masters thesis]. Virginia Tech; 2011. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/34978.

Council of Science Editors:

Regner KT. Combining In Situ Measurements and Advanced Catalyst Layer Modeling in PEM Fuel Cells. [Masters Thesis]. Virginia Tech; 2011. Available from: http://hdl.handle.net/10919/34978

Virginia Tech

10. Garrabrant, Austin Joseph. Analysis of Ionomer-coated Carbon Nanofiber for use in PEM Fuel Cell Catalyst Layers.

Degree: MS, Mechanical Engineering, 2019, Virginia Tech

URL: http://hdl.handle.net/10919/92593

► Proton exchange membrane (PEM) fuel cells have the potential to replace traditional energy conversion systems in many applications, however their widespread adoption is currently limited… (more)

Subjects/Keywords: PEMFC; Fuel Cell; cathode design; electrode; carbon nanofiber

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APA (6^th Edition):

Garrabrant, A. J. (2019). Analysis of Ionomer-coated Carbon Nanofiber for use in PEM Fuel Cell Catalyst Layers. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/92593

Chicago Manual of Style (16^th Edition):

Garrabrant, Austin Joseph. “Analysis of Ionomer-coated Carbon Nanofiber for use in PEM Fuel Cell Catalyst Layers.” 2019. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/92593.

MLA Handbook (7^th Edition):

Garrabrant, Austin Joseph. “Analysis of Ionomer-coated Carbon Nanofiber for use in PEM Fuel Cell Catalyst Layers.” 2019. Web. 07 Mar 2021.

Vancouver:

Garrabrant AJ. Analysis of Ionomer-coated Carbon Nanofiber for use in PEM Fuel Cell Catalyst Layers. [Internet] [Masters thesis]. Virginia Tech; 2019. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/92593.

Council of Science Editors:

Garrabrant AJ. Analysis of Ionomer-coated Carbon Nanofiber for use in PEM Fuel Cell Catalyst Layers. [Masters Thesis]. Virginia Tech; 2019. Available from: http://hdl.handle.net/10919/92593

Virginia Tech

11. Li, Liurui. The Material Separation Process for Recycling End-of-life Li-ion Batteries.

Degree: PhD, Mechanical Engineering, 2020, Virginia Tech

URL: http://hdl.handle.net/10919/100735

► The bursting demand of lithium-ion batteries from portable electronics, electric vehicles, and power grids in the past few years not only facilitate the booming of… (more)

Subjects/Keywords: Battery Recycling; Material Separation; Automated Disassembly; Design of Experiment

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APA (6^th Edition):

Li, L. (2020). The Material Separation Process for Recycling End-of-life Li-ion Batteries. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/100735

Chicago Manual of Style (16^th Edition):

Li, Liurui. “The Material Separation Process for Recycling End-of-life Li-ion Batteries.” 2020. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/100735.

MLA Handbook (7^th Edition):

Li, Liurui. “The Material Separation Process for Recycling End-of-life Li-ion Batteries.” 2020. Web. 07 Mar 2021.

Vancouver:

Li L. The Material Separation Process for Recycling End-of-life Li-ion Batteries. [Internet] [Doctoral dissertation]. Virginia Tech; 2020. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/100735.

Council of Science Editors:

Li L. The Material Separation Process for Recycling End-of-life Li-ion Batteries. [Doctoral Dissertation]. Virginia Tech; 2020. Available from: http://hdl.handle.net/10919/100735

Virginia Tech

12. Ye, Zhou. Effect of Nanoscale Surface Structures on Microbe-Surface Interactions.

Degree: PhD, Mechanical Engineering, 2017, Virginia Tech

URL: http://hdl.handle.net/10919/85387

► Bacteria in nature predominantly grow as biofilms on living and non-living surfaces. The development of biofilms on non-living surfaces is significantly affected by the surface… (more)

▼ Bacteria in nature predominantly grow as biofilms on living and non-living surfaces. The development of biofilms on non-living surfaces is significantly affected by the surface micro/nano topography. The main goal of this dissertation is to study the interaction between microorganisms and nanopatterned surfaces. In order to engineer the surface with well-defined and repeatable nanoscale structures, a new, versatile and scalable nanofabrication method, termed Spun-Wrapped Aligned Nanofiber lithography (SWAN lithography) was developed. This technique enables high throughput fabrication of micro/nano-scale structures on planar and highly non-planar 3D objects with lateral feature size ranging from sub-50 nm to a few microns, which is difficult to achieve by any other method at present. This nanolithography technique was then utilized to fabricate nanostructured electrode surfaces to investigate the role of surface nanostructure size (i.e. 115 nm and 300 nm high) in current production of microbial fuel cells (MFCs). Through comparing the S. oneidensis attachment density and current density (normalized by surface area), we demonstrated the effect of the surface feature size which is independent of the effect on the surface area. In order to better understand the mechanism of microorganism adhesion on nanostructured surfaces, we developed a biophysical model that calculates the total energy of adhered cells as a function of nanostructure size and spacing. Using this model, we predict the attachment density trend for Candida albicans on nanofiber-textured surfaces. The model can be applied at the population level to design surface nanostructures that reduce cell attachment on medical catheters. The biophysical model was also utilized to study the motion of a single Candida albicans yeast cell and to identify the optimal attachment location on nanofiber coated surfaces, thus leading to a better understanding of the cell-substrate interaction upon attachment. Advisors/Committee Members: Behkam, Bahareh (committeechair), Ellis, Michael W. (committeechair), von Spakovsky, Michael R. (committee member), Nain, Amrinder (committee member), Mukhopadhyay, Biswarup (committee member).

Subjects/Keywords: nanopatterning; microbial fuel cell; biophysical model; bacterial adhesion

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APA (6^th Edition):

Ye, Z. (2017). Effect of Nanoscale Surface Structures on Microbe-Surface Interactions. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/85387

Chicago Manual of Style (16^th Edition):

Ye, Zhou. “Effect of Nanoscale Surface Structures on Microbe-Surface Interactions.” 2017. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/85387.

MLA Handbook (7^th Edition):

Ye, Zhou. “Effect of Nanoscale Surface Structures on Microbe-Surface Interactions.” 2017. Web. 07 Mar 2021.

Vancouver:

Ye Z. Effect of Nanoscale Surface Structures on Microbe-Surface Interactions. [Internet] [Doctoral dissertation]. Virginia Tech; 2017. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/85387.

Council of Science Editors:

Ye Z. Effect of Nanoscale Surface Structures on Microbe-Surface Interactions. [Doctoral Dissertation]. Virginia Tech; 2017. Available from: http://hdl.handle.net/10919/85387

13. Verma, Atul. Transients in Polymer Electrolyte Membrane (PEM) Fuel Cells.

Degree: PhD, Mechanical Engineering, 2015, Virginia Tech

URL: http://hdl.handle.net/10919/64247

► The need for energy efficient, clean and quiet, energy conversion devices for mobile and stationary applications has presented proton exchange membrane (PEM) fuel cells as… (more)

▼ The need for energy efficient, clean and quiet, energy conversion devices for mobile and stationary applications has presented proton exchange membrane (PEM) fuel cells as a potential energy source. The use of PEM fuel cells for automotive and other transient applications, where there are rapid changes in load, presents a need for better understanding of transient behavior. In particular at low humidity operations; one of the factors critical to the performance and durability of fuel cell systems is water transport in various fuel cell layers, including water absorption in membrane. An essential aspect to optimization of transient behavior of fuel cells is a fundamental understanding of response of fuel cell system to dynamic changes in load and operating parameters. This forms the first objective of the dissertation. An insight in to the time scales associated with various transport phenomena will be discussed in detail. In the second component on the study, the effects of membrane properties on the dynamic behavior of the fuel cells are analyzed with focus on membrane dry-out for low humidity operations. The mechanical behavior of the membrane is directly related to the changes in humidity levels in membrane and is explored as a part third objective of the dissertation. Numerical studies addressing this objective will be presented. Finally, porous media undergoing physical deposition (or erosion) are common in many applications, including electrochemical systems such as fuel cells (for example, electrodes, catalyst layer s, etc.) and batteries. The transport properties of these porous media are a function of the deposition and the change in the porous structures with time. A dynamic fractal model is introduced to describe such structures undergoing deposition and, in turn, to evaluate the changes in their physical properties as a function of the deposition. Advisors/Committee Members: Pitchumani, Ranga (committeechair), Ellis, Michael W. (committee member), Tafti, Danesh K. (committee member), Case, Scott W. (committee member), Mahajan, Roop L. (committee member).

Subjects/Keywords: Polymer Electrolyte Fuel Cells; Water Content; Steady State Time; Membrane Hydration; Operating Conditions; Design Windows; Mechanical Behavior; Equivalent Plastic Strain; Load Change; Voltage Reversal; Anode Dryout; Degradation; Dynamic Fractal Mode

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APA (6^th Edition):

Verma, A. (2015). Transients in Polymer Electrolyte Membrane (PEM) Fuel Cells. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/64247

Chicago Manual of Style (16^th Edition):

Verma, Atul. “Transients in Polymer Electrolyte Membrane (PEM) Fuel Cells.” 2015. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/64247.

MLA Handbook (7^th Edition):

Verma, Atul. “Transients in Polymer Electrolyte Membrane (PEM) Fuel Cells.” 2015. Web. 07 Mar 2021.

Vancouver:

Verma A. Transients in Polymer Electrolyte Membrane (PEM) Fuel Cells. [Internet] [Doctoral dissertation]. Virginia Tech; 2015. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/64247.

Council of Science Editors:

Verma A. Transients in Polymer Electrolyte Membrane (PEM) Fuel Cells. [Doctoral Dissertation]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/64247

Virginia Tech

14. Siuta, Chase Michael. Measuring Material Properties of Proton Exchange Membranes using Pressure Loaded Blister Testing and Digital Image Correlation.

Degree: MS, Engineering Science and Mechanics, 2011, Virginia Tech

URL: http://hdl.handle.net/10919/76858

► The strength and durability of proton exchange membranes for use in fuel cells has received much attention recently due to the increased push for sustainable… (more)

▼ The strength and durability of proton exchange membranes for use in fuel cells has received much attention recently due to the increased push for sustainable alternatives to the internal combustion engine. To be viable, these alternatives must have comparable lifetimes and power outputs to the internal combustion engines they replace. Chemical degradation was once viewed as the most common culprit of early fuel cell failure, but as membranes and catalysts improved, mechanical failure became an important factor. As a result, fundamental research on the mechanically-induced failure mechanisms of fuel cell membranes, coupled with development and processing of less expensive membranes, has become an important topic. The use of the blister test geometry, along with digital image correlation of the deformed shape, creates a self-contained analysis tool useful for measuring the biaxial strength of membranes. In this work, blister tests are used to measure biaxial stress and strain for fuel cell membranes subjected to ramped pressure loading to form stress-strain curves that indicate the onset of yielding under biaxial stress conditions. Stress-life curves are developed experimentally for Gore-Selec? series 57 members using data collected under constant pressure conditions. These results are used to predict blister failure under ramped and fatigue loadings. A newly implemented hydrocarbon membrane system is evaluated with constant-pressure-to-leak blister testing. Improved strength following an isothermal hold at 100°C (pretreatment) is shown to occur. Ramped pressure testing indicates that the material after the pretreatment is stiffer and has a higher yield stress than the material before treatment. Morphological and constitutive characterization indicated differences in the materials that are consistent with the improved performance. Advisors/Committee Members: Case, Scott W. (committeechair), Li, Yongqiang (committee member), Ellis, Michael W. (committee member), Dillard, David A. (committee member).

Subjects/Keywords: biaxial strength; pressure-loaded blister test; proton exchange membrane; digital image correlation; hydrocarbon membrane; PFCB; linear damage accumulation

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APA (6^th Edition):

Siuta, C. M. (2011). Measuring Material Properties of Proton Exchange Membranes using Pressure Loaded Blister Testing and Digital Image Correlation. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/76858

Chicago Manual of Style (16^th Edition):

Siuta, Chase Michael. “Measuring Material Properties of Proton Exchange Membranes using Pressure Loaded Blister Testing and Digital Image Correlation.” 2011. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/76858.

MLA Handbook (7^th Edition):

Siuta, Chase Michael. “Measuring Material Properties of Proton Exchange Membranes using Pressure Loaded Blister Testing and Digital Image Correlation.” 2011. Web. 07 Mar 2021.

Vancouver:

Siuta CM. Measuring Material Properties of Proton Exchange Membranes using Pressure Loaded Blister Testing and Digital Image Correlation. [Internet] [Masters thesis]. Virginia Tech; 2011. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/76858.

Council of Science Editors:

Siuta CM. Measuring Material Properties of Proton Exchange Membranes using Pressure Loaded Blister Testing and Digital Image Correlation. [Masters Thesis]. Virginia Tech; 2011. Available from: http://hdl.handle.net/10919/76858

15. Beach, Jeremy. Preparation and Electrochemical Testing of Flexible Carbon Nanofiber Electrodes from Electrospinning.

Degree: PhD, Chemistry, 2017, Virginia Tech

URL: http://hdl.handle.net/10919/89627

► The purpose of this research project was to determine the processing conditions necessary for preparing flexible carbon nanofiber electrodes by electrospinning and to explore various… (more)

▼ The purpose of this research project was to determine the processing conditions necessary for preparing flexible carbon nanofiber electrodes by electrospinning and to explore various applications for those electrodes. It was found that by varying only the relative humidity while electrospinning a poly(acrylonitrile) precursor, fragile or flexible freestanding carbon nanofiber electrodes were prepared. The relative humidity during electrospinning controlled the fiber diameter, the bulk porosity of the material, and flexibility of the final carbon electrode. Higher porosity mats electrospun in a high relative humidity environment prevented fiber sintering, which if not minimized, resulted in non-flexible carbon electrodes. Both flexible and fragile electrodes were freestanding, binderless, and collectorless. Additionally, they required no further processing before use and were 100 wt.% active material. When cycled galvanostatically as a lithium ion battery anode, the flexible electrode exhibited a specific capacity of 379 mAH g-1 at the 100th cycle and capacity retention was 97.4% relative to the fifth cycle. When applied as an active material support electrode for lithium ion battery cathodes, the carbon support was successfully utilized with both micron and nano structured active material and cycled for 100 cycles with limited capacity loss. The same electrodes were also found to be a viable replacement for Pt electrode based actuators/artificial muscles. However, this application requires much further research to understand better the required processing and effects of the physical properties of the electrode on actuator performance. In addition to this, the flexible electrodes have a wide variety of other potential applications including, electrochemical storage and conversion devices, chemical sensing, and filtration. The focus of this work was electrochemical storage and conversion devices in the form of lithium ion battery anodes and cathodes as well as ionic polymer composite actuators. Advisors/Committee Members: Moore, Robert Bowen (committeechair), Ellis, Michael W. (committee member), Esker, Alan R. (committee member), Long, Timothy E. (committee member).

Subjects/Keywords: Electrospinning; Nano; Carbon; Electrode; Batteries

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APA (6^th Edition):

Beach, J. (2017). Preparation and Electrochemical Testing of Flexible Carbon Nanofiber Electrodes from Electrospinning. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/89627

Chicago Manual of Style (16^th Edition):

Beach, Jeremy. “Preparation and Electrochemical Testing of Flexible Carbon Nanofiber Electrodes from Electrospinning.” 2017. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/89627.

MLA Handbook (7^th Edition):

Beach, Jeremy. “Preparation and Electrochemical Testing of Flexible Carbon Nanofiber Electrodes from Electrospinning.” 2017. Web. 07 Mar 2021.

Vancouver:

Beach J. Preparation and Electrochemical Testing of Flexible Carbon Nanofiber Electrodes from Electrospinning. [Internet] [Doctoral dissertation]. Virginia Tech; 2017. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/89627.

Council of Science Editors:

Beach J. Preparation and Electrochemical Testing of Flexible Carbon Nanofiber Electrodes from Electrospinning. [Doctoral Dissertation]. Virginia Tech; 2017. Available from: http://hdl.handle.net/10919/89627

Virginia Tech

16. Thompson, Willis Hope III. Numerical Analysis of Thermal Behavior and Fluid Flow in Geothermal Energy Piles.

Degree: MS, Mechanical Engineering, 2013, Virginia Tech

URL: http://hdl.handle.net/10919/24013

► Geothermal heat exchangers are a growing energy technology that improve the energy efficiency of heating and cooling systems in buildings. Vertical borehole heat exchangers (BHE)… (more)

▼ Geothermal heat exchangers are a growing energy technology that improve the energy efficiency of heating and cooling systems in buildings. Vertical borehole heat exchangers (BHE) coupled with ground source heat pumps have been widely developed and researched in the past century. The major disadvantage of BHEs is the initial capital cost required to drill the boreholes. Geothermal energy piles (GEP) were developed to help offset the high initial cost of these systems. A GEP combines ground source heat pump technology with deep earth structural foundations of buildings. GEPs are relatively new technology and robust standards and guidelines have not yet been developed for the design of these systems. The main operational difference between GEPs and conventional BHEs is the length and diameter of the below ground heat exchangers. The diameter of a GEP is much larger and the length is typically shorter than BHEs. Computational fluid dynamics (CFD) analysis is used in this study to investigate and better understand how structural piles perform as geothermal heat exchangers. The CFD analysis is used to simulate an existing experimental energy pile test. The experimental test is modeled as built including fluid modeling to provide additional detail into the behavior of the circulation fluid within the pile. Two comparisons of large diameter GEPs are made using CFD analysis to gain knowledge of the effects of varying pile diameter and loop configuration. The thermal response test was successfully modeled using the CFD model. The CFD results closely match the results of the field test. The large diameter comparisons show that the performance of an energy pile will increase as the diameter increases with a constant loop density. Multiple numbers of loops were tested in a constant diameter pile and the results show that with symmetrically placed loops the performance will increase with a greater number of loops in the pile. Advisors/Committee Members: Ekkad, Srinath V. (committeechair), Olgun, Celal Guney (committee member), Wheeler, Joseph H. (committee member), Ellis, Michael W. (committee member).

Subjects/Keywords: Geothermal Energy Pile; Ground Source Heat Pump

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APA (6^th Edition):

Thompson, W. H. I. (2013). Numerical Analysis of Thermal Behavior and Fluid Flow in Geothermal Energy Piles. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/24013

Chicago Manual of Style (16^th Edition):

Thompson, Willis Hope III. “Numerical Analysis of Thermal Behavior and Fluid Flow in Geothermal Energy Piles.” 2013. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/24013.

MLA Handbook (7^th Edition):

Thompson, Willis Hope III. “Numerical Analysis of Thermal Behavior and Fluid Flow in Geothermal Energy Piles.” 2013. Web. 07 Mar 2021.

Vancouver:

Thompson WHI. Numerical Analysis of Thermal Behavior and Fluid Flow in Geothermal Energy Piles. [Internet] [Masters thesis]. Virginia Tech; 2013. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/24013.

Council of Science Editors:

Thompson WHI. Numerical Analysis of Thermal Behavior and Fluid Flow in Geothermal Energy Piles. [Masters Thesis]. Virginia Tech; 2013. Available from: http://hdl.handle.net/10919/24013

Virginia Tech

17. Forbey, Scott. Design and Characterization of Electrospun Mats with Tailored Morphologies for Enhanced Active Layer Performance in Energy Conversion and Energy Storage Applications.

Degree: PhD, Chemistry, 2014, Virginia Tech

URL: http://hdl.handle.net/10919/52627

► The goal of this research was to utilize the morphological control inherently imparted by the electrospinning process to improve the active layer performance in energy… (more)

▼ The goal of this research was to utilize the morphological control inherently imparted by the electrospinning process to improve the active layer performance in energy conversion devices as well as to better understand the relationship between morphology and performance in energy storage devices. Discrete control of the active layer morphology can promote exciton dissociation in organic photovoltaic cells (OPVs), whereas developing efficient ion diffusion pathways and beneficial polymer-ion interaction in polymer-gel electrolytes is demonstrated to result in enhanced battery performance. We demonstrate the ability to develop unique morphologies in Poly(3-hexafluoro propylene) (P3HT) films with energy storage applications using various electrospinning techniques. Electrospinning in a solvent-saturated atmosphere allows for the design of ribbon architectures with polymer domains on the order of 5-10 um. These ribbon structures form what appear to be bi-continuous films, which could then be filled with an acceptor / fullerene type material to create a bulk heterojucton for OPV devices. Dropping chloroform onto the electrospinning needle during the spinning process results in P3HT fibers with porous surfaces. These fibers have diameters of ~ 2 um. Using a coaxial needle to electrospin a P3HT solution in the core, and a CHCl3 sheath solution created hybrid ribbon-fiber structures. These structures have even smaller domain sizes than the ribbons created using a solvent saturated atmosphere. Cospinning P3HT with sacrificial polymers results in P3HT fiber morphologies upon removal of the sacrificial template polymer. Additionally, introducing P3HT into an established fiber matrix results in fibrous P3HT architectures after the template fibers are removed. Developing hybrid polymer-gel electrolytes using crosslinked PEO electrospun fibers results in membranes with high affinity for liquid electrolyte components. These electrospun PEO fiber mats exhibit excellent ionic conductivities at room temperature (12 mS/cm) exceeding an electrospun PVDF control. Furthermore, the PEO fiber mats can absorb nearly three times as much liquid electrolyte as the PVDF control. PEO has been show to interact with lithium salts to aid in dissociation and diffusion during battery cycling. Although the ionic conductivity data suggest PEO to be a superior electrolyte, pulsed-field-gradient NMR shows that lithium diffusion is faster in PVDF samples. From coin cell discharge experiments, PEO is believed to interact strongly with Li+ ions, inhibiting them from diffusing rapidly during fast charge/discharge rates. However, PEO/PETA fiber electrolytes show nearly 100% theoretical capacity discharge at C/100 and a capacity retention of ~ 35% at a C/5 discharge rate in contrast to a glass fiber separator which shows only a capacity that is approximately 85% of the theoretical value. The unique mechanical properties of PEO/PETA electrospun mats could lead to interesting artificial skin and wound healing applications. Upon crosslinking… Advisors/Committee Members: Moore, Robert Bowen (committeechair), Ellis, Michael W. (committee member), Heflin, James R. (committee member), Gibson, Harry W. (committee member), Deck, Paul A. (committee member).

Subjects/Keywords: electrospinning; organic photovoltaic; bulk heterojunction; lithium polymer battery; ionic conductivity; photo initiator; cross linking; energy conversion; energy storage

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APA (6^th Edition):

Forbey, S. (2014). Design and Characterization of Electrospun Mats with Tailored Morphologies for Enhanced Active Layer Performance in Energy Conversion and Energy Storage Applications. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/52627

Chicago Manual of Style (16^th Edition):

Forbey, Scott. “Design and Characterization of Electrospun Mats with Tailored Morphologies for Enhanced Active Layer Performance in Energy Conversion and Energy Storage Applications.” 2014. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/52627.

MLA Handbook (7^th Edition):

Forbey, Scott. “Design and Characterization of Electrospun Mats with Tailored Morphologies for Enhanced Active Layer Performance in Energy Conversion and Energy Storage Applications.” 2014. Web. 07 Mar 2021.

Vancouver:

Forbey S. Design and Characterization of Electrospun Mats with Tailored Morphologies for Enhanced Active Layer Performance in Energy Conversion and Energy Storage Applications. [Internet] [Doctoral dissertation]. Virginia Tech; 2014. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/52627.

Council of Science Editors:

Forbey S. Design and Characterization of Electrospun Mats with Tailored Morphologies for Enhanced Active Layer Performance in Energy Conversion and Energy Storage Applications. [Doctoral Dissertation]. Virginia Tech; 2014. Available from: http://hdl.handle.net/10919/52627

Virginia Tech

18. Younis, Aimen M. Modeling the Non-equilibrium Phenomenon of Diffusion in Closed and Open Systems at an Atomistic Level Using Steepest-Entropy-Ascent Quantum Thermodynamics.

Degree: PhD, Mechanical Engineering, 2015, Virginia Tech

URL: http://hdl.handle.net/10919/55127

► Intrinsic quantum Thermodynamics (IQT) is a theory that unifies thermodynamics and quantum mechanics into a single theory. Its mathematical framework, steepest-entropy-ascent quantum thermodynamics (SEAQT), can… (more)

▼ Intrinsic quantum Thermodynamics (IQT) is a theory that unifies thermodynamics and quantum mechanics into a single theory. Its mathematical framework, steepest-entropy-ascent quantum thermodynamics (SEAQT), can be used to model and describe the non-equilibrium phenomenon of diffusion based on the principle of steepest-entropy ascent. The research presented in this dissertation demonstrates the capability of this framework to model and describe diffusion at atomistic levels and is used here to develop a non-equilibrium-based model for an isolated system in which He3 diffuses in He4. The model developed is able to predict the non-equilibrium and equilibrium characteristics of diffusion as well as capture the differences in behavior of fermions (He3) and bosons (He4). The SEAQT framework is also used to develop the transient and steady-state model for an open system in which oxygen diffuses through a tin anode. The two forms of the SEAQT equation of motion are used. The first, which only involves a dissipation term, is applied to the state evolution of the isolated system as its state relaxes from some initial non-equilibrium state to stable equilibrium. The second form, the so-called extended SEAQT equation of motion, is applied to the transient state evolution of an open system undergoing a dissipative process as well mass-interactions with two mass reservoirs. In this case, the state of the system relaxes from some initial transient state to steady state. Model predictions show that the non-equilibrium thermodynamic path that the isolated system takes significantly alters the diffusion data from that of the equilibrium-based models for isolated atomistic-level systems found in literature. Nonetheless, the SEAQT equilibrium predications for He3 and He4 capture the same trends as those found in the literature providing a point of validation for the SEAQT framework. As to the SEAQT results for the open system, there is no data in the literature with which to compare since the results presented here are completely original to this work. Advisors/Committee Members: von Spakovsky, Michael R. (committeechair), Ellis, Michael W. (committee member), Dancey, Clinton L. (committee member), Verda, Vittorio (committee member), Huxtable, Scott T. (committee member).

Subjects/Keywords: atomistic-level diffusion; non-equilibrium; transient; and steady state diffusivities; non-equilibrium thermodynamics; steepest-entropy-ascent quantum thermodynamics.

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APA (6^th Edition):

Younis, A. M. (2015). Modeling the Non-equilibrium Phenomenon of Diffusion in Closed and Open Systems at an Atomistic Level Using Steepest-Entropy-Ascent Quantum Thermodynamics. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/55127

Chicago Manual of Style (16^th Edition):

Younis, Aimen M. “Modeling the Non-equilibrium Phenomenon of Diffusion in Closed and Open Systems at an Atomistic Level Using Steepest-Entropy-Ascent Quantum Thermodynamics.” 2015. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/55127.

MLA Handbook (7^th Edition):

Younis, Aimen M. “Modeling the Non-equilibrium Phenomenon of Diffusion in Closed and Open Systems at an Atomistic Level Using Steepest-Entropy-Ascent Quantum Thermodynamics.” 2015. Web. 07 Mar 2021.

Vancouver:

Younis AM. Modeling the Non-equilibrium Phenomenon of Diffusion in Closed and Open Systems at an Atomistic Level Using Steepest-Entropy-Ascent Quantum Thermodynamics. [Internet] [Doctoral dissertation]. Virginia Tech; 2015. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/55127.

Council of Science Editors:

Younis AM. Modeling the Non-equilibrium Phenomenon of Diffusion in Closed and Open Systems at an Atomistic Level Using Steepest-Entropy-Ascent Quantum Thermodynamics. [Doctoral Dissertation]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/55127

Virginia Tech

19. Finlay, Katherine A. Characterization of Sulfonated Perfluorocyclobutane /Poly(Vinylidene Difluoride)-co-Hexafluoropropylene (PFCB/PVDF-HFP) Blends for Use as Proton Exchange Membranes.

Degree: PhD, Macromolecular Science and Engineering, 2013, Virginia Tech

URL: http://hdl.handle.net/10919/47475

► The research herein focuses on the characterization of a PFCB/PVDF-HFP (70:30 wt:wt) blend fuel cell membrane including the constitutive and morphological properties, how these properties… (more)

▼ The research herein focuses on the characterization of a PFCB/PVDF-HFP (70:30 wt:wt) blend fuel cell membrane including the constitutive and morphological properties, how these properties predict the stresses incurred under fuel cell operating conditions, and how these properties change over time under fuel cell operating conditions. Characterization was performed to mimic temperature and moisture conditions found in operating fuel cells to understand how these materials will behave in service. This included thermal and hygral expansion, mass uptake, and the stress relaxation modulus. These constitutive properties were chosen for characterization such that a model could be created to predict the stresses incurred during fuel cell operation, and examine how these stresses may change under different operating conditions and over time. Based on the results of this model, lifetime predictions were made resulting in recommendations to further extend the operating time of this membrane beyond the DOE 5000 hr requirement. Stress predictions are useful, however if the material properties are changing over time under the fuel cell operating conditions, they may no longer be valid. Therefore, PFCB/PVDF-HFP membranes were conditioned for different amounts of time under conditions similar to those commonly found in operating fuel cells. These conditioned membranes were then characterized and compared with solvent exchanged membranes, the same materials used for previous material characterization. The properties examined included stress relaxation modulus, bi-axial strength, mass uptake, water diffusion, and proton conductivity. To further understand any changes noted in these properties after different environmental exposures, morphological analysis was performed. This included small angle x-ray scattering, infrared spectroscopy, transmission electron microscopy, and differential scanning calorimetry. It was initially found that the proton conductivity decreased severely when the material was immersed at high temperatures over short time periods. This was consistent with changes noted in other properties, and morphological analysis showed a decrease in the ionic network as well as an increase in the phase separation of the PFCB block copolymer as well as the PVDF-HFP crystallinity. These large morphological changes could be very detrimental while in service, resulting in early termination of the fuel cell. However, it was also noted that if these materials are annealed at high temperature (140"C), the negative property changes are abated. This abatement is again tied to the morphology of the material, as annealing the material at high temperature creates stronger physical crosslinks, and induces a small amount of chemical crosslinking via condensation of the sulfonic acid groups, thus allowing the stress predictions performed earlier to have greater validity. Therefore, it is important to not only understand the properties of a material during characterization, but also the underlying… Advisors/Committee Members: Moore, Robert Bowen (committeechair), Dillard, David A. (committeechair), Case, Scott W. (committee member), McGrath, James E. (committee member), Lai, Yeh-Hung (committee member), Ellis, Michael W. (committee member).

Subjects/Keywords: Perfluorocyclobutane; Polyvinylidene Difluoride; Polymer Blend; Proton Exchange Membrane; Fuel Cell; Viscoelasticity; Time Tempe

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APA (6^th Edition):

Finlay, K. A. (2013). Characterization of Sulfonated Perfluorocyclobutane /Poly(Vinylidene Difluoride)-co-Hexafluoropropylene (PFCB/PVDF-HFP) Blends for Use as Proton Exchange Membranes. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/47475

Chicago Manual of Style (16^th Edition):

Finlay, Katherine A. “Characterization of Sulfonated Perfluorocyclobutane /Poly(Vinylidene Difluoride)-co-Hexafluoropropylene (PFCB/PVDF-HFP) Blends for Use as Proton Exchange Membranes.” 2013. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/47475.

MLA Handbook (7^th Edition):

Finlay, Katherine A. “Characterization of Sulfonated Perfluorocyclobutane /Poly(Vinylidene Difluoride)-co-Hexafluoropropylene (PFCB/PVDF-HFP) Blends for Use as Proton Exchange Membranes.” 2013. Web. 07 Mar 2021.

Vancouver:

Finlay KA. Characterization of Sulfonated Perfluorocyclobutane /Poly(Vinylidene Difluoride)-co-Hexafluoropropylene (PFCB/PVDF-HFP) Blends for Use as Proton Exchange Membranes. [Internet] [Doctoral dissertation]. Virginia Tech; 2013. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/47475.

Council of Science Editors:

Finlay KA. Characterization of Sulfonated Perfluorocyclobutane /Poly(Vinylidene Difluoride)-co-Hexafluoropropylene (PFCB/PVDF-HFP) Blends for Use as Proton Exchange Membranes. [Doctoral Dissertation]. Virginia Tech; 2013. Available from: http://hdl.handle.net/10919/47475

Virginia Tech

20. Agarwal, Ritesh. Design and Modeling of a Novel Direct Carbon Molten Carbonate Fuel Cell with Porous Bed Electrodes.

Degree: PhD, Mechanical Engineering, 2015, Virginia Tech

URL: http://hdl.handle.net/10919/51251

► A novel concept has been developed for the direct carbon fuel cell (DCFC) based on molten carbonate recirculating electrolyte. In the cathode, co-current flow of… (more)

▼ A novel concept has been developed for the direct carbon fuel cell (DCFC) based on molten carbonate recirculating electrolyte. In the cathode, co-current flow of electrolyte with entrained gases carbon dioxide and oxygen is sent in the upward direction through a porous bed grid. In the anode, co-current flow of a slurry of electrolyte entrained with carbon particles is sent in the downward direction through a porous bed grid. The gases carbon dioxide and oxygen in the cathode react on the grid surface to form carbonate ions. The carbonate ions are then transported via conduction to the anode for reaction with carbon to produce carbon dioxide for temperatures under 750 deg C. A mathematical model based on this novel DCFC concept has been developed. The model includes governing equations that describe the transport and electrochemical processes taking place in both the anode and cathode and a methodology for solving these equations. Literature correlations from multi-phase packed-bed chemical reactors were used to estimate phase hold-up and mass transfer coefficients. CO production and axial diffusion were neglected. The results demonstrated that activation and ohmic polarization were important to the cell output. The impact of concentration polarization to the cell output was comparatively small. The bed depths realized were of the order of 10cm which is not large enough to accommodate the economies of scale for a large scale plant, however thousands of smaller cells (10 m² area) in series could be built to scale up to a 10 MW industrial plant. Limiting current densities of the order of 1000-1500 A/m² were achieved for various operating conditions. Maximum power densities of 200-350 W/m² with current densities of 500-750 A/m², and cell voltages of 0.4-0.5 V have been achieved at a temperature of 700 deg C. Over temperatures ranging from 700 to 800 deg C, results from the modeled cell are comparable with results seen in the literature for direct carbon fuel cells that are similar in design and construction. Advisors/Committee Members: Kornhauser, Alan A. (committeechair), Nelson, Douglas J. (committee member), Ellis, Michael W. (committee member), von Spakovsky, Michael R. (committee member), Vick, Brian (committee member), Morris, Amanda (committee member).

Subjects/Keywords: Direct carbon fuel cell; molten carbonate; modeling; carbon slurry; molten salt; fuel cell; DCFC

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APA (6^th Edition):

Agarwal, R. (2015). Design and Modeling of a Novel Direct Carbon Molten Carbonate Fuel Cell with Porous Bed Electrodes. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/51251

Chicago Manual of Style (16^th Edition):

Agarwal, Ritesh. “Design and Modeling of a Novel Direct Carbon Molten Carbonate Fuel Cell with Porous Bed Electrodes.” 2015. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/51251.

MLA Handbook (7^th Edition):

Agarwal, Ritesh. “Design and Modeling of a Novel Direct Carbon Molten Carbonate Fuel Cell with Porous Bed Electrodes.” 2015. Web. 07 Mar 2021.

Vancouver:

Agarwal R. Design and Modeling of a Novel Direct Carbon Molten Carbonate Fuel Cell with Porous Bed Electrodes. [Internet] [Doctoral dissertation]. Virginia Tech; 2015. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/51251.

Council of Science Editors:

Agarwal R. Design and Modeling of a Novel Direct Carbon Molten Carbonate Fuel Cell with Porous Bed Electrodes. [Doctoral Dissertation]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/51251

Virginia Tech

21. Cano-Andrade, Sergio. Thermodynamic Based Framework for Determining Sustainable Electric Infrastructures as well as Modeling of Decoherence in Quantum Composite Systems.

Degree: PhD, Mechanical Engineering, 2014, Virginia Tech

URL: http://hdl.handle.net/10919/25878

► In this dissertation, applications of thermodynamics at the macroscopic and quantum levels of description are developed. Within the macroscopic level, an upper-level Sustainability Assessment Framework… (more)

▼ In this dissertation, applications of thermodynamics at the macroscopic and quantum levels of description are developed. Within the macroscopic level, an upper-level Sustainability Assessment Framework (SAF) is proposed for evaluating the sustainable and resilient synthesis/design and operation of sets of small renewable and non-renewable energy production technologies coupled to power production transmission and distribution networks via microgrids. The upper-level SAF is developed in accord with the four pillars of sustainability, i.e., economic, environmental, technical and social. A superstructure of energy producers with a fixed transmission network initially available is synthesized based on the day with the highest energy demand of the year, resulting in an optimum synthesis, design, and off-design network configuration. The optimization is developed in a quasi-stationary manner with an hourly basis, including partial-load behavior for the producers. Since sustainability indices are typically not expressed in the same units, multicriteria decision making methods are employed to obtain a composite sustainability index. Within the quantum level of description, steepest-entropy-ascent quantum thermodynamics (SEA-QT) is used to model the phenomenon of decoherence. The two smallest microscopic composite systems encountered in Nature are studied. The first of these is composed of two two-level-type particles, while the second one is composed of a two-level-type particle and an electromagnetic field. Starting from a non-equilibrium state of the composite and for each of the two different composite systems, the time evolution of the state of the composite as well as that of the reduced and locally-perceived states of the constituents are traced along their relaxation towards stable equilibrium at constant system energy. The modeling shows how the initial entanglement and coherence between constituents are reduced during the relaxation towards a state of stable equilibrium. When the constituents are non-interacting, the initial coherence is lost once stable equilibrium is reached. When they are interacting, the coherence in the final stable equilibrium state is only that due to the interaction. For the atom-photon field composite system, decoherence is compared with data obtained experimentally by the CQED group at Paris. The SEA-QT method applied in this dissertation provides an alternative and comprehensive explanation to that obtained with the "open system" approach of Quantum Thermodynamics (QT) and its associated quantum master equations of the Kossakowski-Lindblad-Gorini-Sudarshan type. Advisors/Committee Members: von Spakovsky, Michael R. (committeechair), Nelson, Douglas J. (committee member), Beretta, Gian Paolo (committee member), Ellis, Michael W. (committee member), Hobbs, Benjamin Field (committee member), Mili, Lamine M. (committee member).

Subjects/Keywords: sustainability; resiliency; microgrids; multiobjective optimization; entanglement; decoherence; quantum thermodynamics; steepest-entropy-ascent modeling

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APA (6^th Edition):

Cano-Andrade, S. (2014). Thermodynamic Based Framework for Determining Sustainable Electric Infrastructures as well as Modeling of Decoherence in Quantum Composite Systems. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/25878

Chicago Manual of Style (16^th Edition):

Cano-Andrade, Sergio. “Thermodynamic Based Framework for Determining Sustainable Electric Infrastructures as well as Modeling of Decoherence in Quantum Composite Systems.” 2014. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/25878.

MLA Handbook (7^th Edition):

Cano-Andrade, Sergio. “Thermodynamic Based Framework for Determining Sustainable Electric Infrastructures as well as Modeling of Decoherence in Quantum Composite Systems.” 2014. Web. 07 Mar 2021.

Vancouver:

Cano-Andrade S. Thermodynamic Based Framework for Determining Sustainable Electric Infrastructures as well as Modeling of Decoherence in Quantum Composite Systems. [Internet] [Doctoral dissertation]. Virginia Tech; 2014. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/25878.

Council of Science Editors:

Cano-Andrade S. Thermodynamic Based Framework for Determining Sustainable Electric Infrastructures as well as Modeling of Decoherence in Quantum Composite Systems. [Doctoral Dissertation]. Virginia Tech; 2014. Available from: http://hdl.handle.net/10919/25878

Virginia Tech

22. May, Jessica Anne. Development of an Experimentally Validated Non-linear Viscoelastic Viscoplastic Model for a Novel Fuel Cell Membrane Material.

Degree: PhD, Mechanical Engineering, 2014, Virginia Tech

URL: http://hdl.handle.net/10919/46977

► The proton exchange membrane (PEM) is a key component in proton exchange membrane fuel cells (PEMFCs). During standard fuel cell operation, the PEM degrades due… (more)

▼ The proton exchange membrane (PEM) is a key component in proton exchange membrane fuel cells (PEMFCs). During standard fuel cell operation, the PEM degrades due to cyclic hygrothermal loads, resulting in performance loss or total failure. Improvement of current PEM materials and development of cheaper, more durable materials is essential to the commercialization of PEMFC technology, which may provide an attractive alternative energy source for transportation. This dissertation investigates a new PEM material which is a blend of sulfonated perfluorocyclobutane (PFCB) and polyvinylidene fluoride (PVDF). Hereafter referred to as PFCB/PVDF, this polymer blend was developed by General Motors Company(TM) as a potential replacement for the current benchmark PEM, the DuPont(TM) product Nafion®. The PFCB/PVDF blend is less costly to manufacture than standard PEM materials and investigations into its long-term mechanical durability are ongoing. Specifically, this document discusses the experimental and analytical work performed in the material characterization, constitutive expression development, and implementation of that expression into uniaxial and biaxial finite element geometries. Extension of the model to time-varying temperature and moisture conditions is also explored. The uniaxial finite element model uses a non-linear viscoelastic viscoplastic (NLVE-VP) constitutive expression with parameters determined from uniaxial creep and recovery experiments at a single environmental condition. Validation tests show that this model accurately predicts results from uniaxial tension experiments, such as stress relaxation, force ramp, and multistep creep and recovery, to stresses of 8 MPa and strains approaching 15%, which is the maximum hygrothermal strain expected in an operating fuel cell. The biaxial finite element model combines the NLVE-VP constitutive expression with the geometry of a pressure-loaded blister experiment, which better approximates fuel cell membrane constraints. Results from the biaxial model are compared to experimental results. The model accurately predicts strain in the blister test but predicts stresses that differ from those estimated from blister curvature. Additionally, it is found that both the non-linear viscoelastic and viscoplastic parameters are functions of the operating environment. Future experimental work is needed to characterize that dependence before the constitutive model is used to simulate the response of the PFCB/PVDF blend to fuel cell operating conditions. Advisors/Committee Members: Ellis, Michael W. (committeechair), Case, Scott W. (committee member), Lai, Yeh-Hung (committee member), Dillard, David A. (committee member), West, Robert L. (committee member).

Subjects/Keywords: proton exchange membrane; polymer; non-linear viscoelastic; viscoplastic; constitutive model; finite element analysis

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APA (6^th Edition):

May, J. A. (2014). Development of an Experimentally Validated Non-linear Viscoelastic Viscoplastic Model for a Novel Fuel Cell Membrane Material. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/46977

Chicago Manual of Style (16^th Edition):

May, Jessica Anne. “Development of an Experimentally Validated Non-linear Viscoelastic Viscoplastic Model for a Novel Fuel Cell Membrane Material.” 2014. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/46977.

MLA Handbook (7^th Edition):

May, Jessica Anne. “Development of an Experimentally Validated Non-linear Viscoelastic Viscoplastic Model for a Novel Fuel Cell Membrane Material.” 2014. Web. 07 Mar 2021.

Vancouver:

May JA. Development of an Experimentally Validated Non-linear Viscoelastic Viscoplastic Model for a Novel Fuel Cell Membrane Material. [Internet] [Doctoral dissertation]. Virginia Tech; 2014. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/46977.

Council of Science Editors:

May JA. Development of an Experimentally Validated Non-linear Viscoelastic Viscoplastic Model for a Novel Fuel Cell Membrane Material. [Doctoral Dissertation]. Virginia Tech; 2014. Available from: http://hdl.handle.net/10919/46977

Virginia Tech

23. Radhakrishnan, Karthik Narayanan. Evaluation of the Cycle Profile Effect on the Degradation of Commercial Lithium Ion Batteries.

Degree: PhD, Mechanical Engineering, 2017, Virginia Tech

URL: http://hdl.handle.net/10919/84420

► Major vehicle manufacturers are committed to expand their electrified vehicle fleet in upcoming years to meet fuel efficiency goals. Understanding the effect of the charge/discharge… (more)

Subjects/Keywords: Lithium ion batteries; capacity degradation; cycle profile

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APA (6^th Edition):

Radhakrishnan, K. N. (2017). Evaluation of the Cycle Profile Effect on the Degradation of Commercial Lithium Ion Batteries. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/84420

Chicago Manual of Style (16^th Edition):

Radhakrishnan, Karthik Narayanan. “Evaluation of the Cycle Profile Effect on the Degradation of Commercial Lithium Ion Batteries.” 2017. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/84420.

MLA Handbook (7^th Edition):

Radhakrishnan, Karthik Narayanan. “Evaluation of the Cycle Profile Effect on the Degradation of Commercial Lithium Ion Batteries.” 2017. Web. 07 Mar 2021.

Vancouver:

Radhakrishnan KN. Evaluation of the Cycle Profile Effect on the Degradation of Commercial Lithium Ion Batteries. [Internet] [Doctoral dissertation]. Virginia Tech; 2017. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/84420.

Council of Science Editors:

Radhakrishnan KN. Evaluation of the Cycle Profile Effect on the Degradation of Commercial Lithium Ion Batteries. [Doctoral Dissertation]. Virginia Tech; 2017. Available from: http://hdl.handle.net/10919/84420

Virginia Tech

24. Divoux, Gilles Michel Marc. Properties and Performance of Polymeric Materials Used in Fuel Cell Applications.

Degree: PhD, Macromolecular Science and Engineering, 2012, Virginia Tech

URL: http://hdl.handle.net/10919/26374

► Over the past three decades, the steady decrease in fossil energy resources, combined with a sustained increase in the demand for clean energy, has led… (more)

▼ Over the past three decades, the steady decrease in fossil energy resources, combined with a sustained increase in the demand for clean energy, has led the scientific community to develop new ways to produce energy. As is well known, one of the main challenges to overcome with fossil fuel-based energy sources is the reduction or even elimination of pollutant gases in the atmosphere. Although some advances have helped to slow the emission of greenhouse gases into the atmosphere (e.g., electric cars and more fuel-efficient gas-burning automobiles), most experts agree that it is not enough. Proton Exchange Membrane (PEM) fuel cells have been widely recognized as a potentially viable alternative for portable and stationary power generation, as well as for transportation. However, the widespread commercialization Proton Exchange Membrane Fuel Cells (PEMFCs) involves a thorough understanding of complex scientific and technological issues. This study investigated the various structure-property relationships and materials durability parameters associated with PEMFC development. First, the correlation between perfluorinated ionomer membranes and processing/performance issues in fuel cell systems was investigated. As confirmed by small-angle X-ray scattering data, impedance analysis, and dynamic mechanical analysis, solution processing with mixed organic-inorganic counterions was found to be effective in producing highly arranged perfluorinated sulfonic acid ionomer (PFSI) membranes with more favorable organization of the ionic domain. Moreover, thermal annealing was shown to enhance the proton mobility, thereby facilitating reorganization of the polymer backbone and the hydrophilic region for improved crystallinity and proton transport properties. This research also confirmed an increase in water uptake in the solution-processed membranes under investigation, which correlated to an increase in proton conductivity. Thus, annealing and solution-processing techniques were shown to be viable ways for controlling morphology and modulating the properties/performance of PFSI membranes. Second, this study investigated the role of the morphology on water and proton transport in perfluorinated ionomers. When annealed at high temperatures, a significant decrease in water uptake and an increase in crystallinity were observed, both of which are detrimental to fuel cell performance. Additionally, controlling the drying process was found to be crucial for optimizing the properties and performance of these membranes, since drying at temperatures close or above the Î±-relaxation temperature causes a major reorganization within the ionic domains. Third, although many investigations have looked at key PEMFC components, (e.g., the membrane, the catalyst, and the bipolar plates), there have been few studies of more â minorâ componentsâ namely, the performance and durability of seals, sealants, and adhesives, which are also exposed to harsh environmental conditions. When seals degrade or fail, reactant gases leak or are mixed,… Advisors/Committee Members: Moore, Robert Bowen (committeechair), Baird, Donald G. (committee member), Ellis, Michael W. (committee member), McGrath, James E. (committee member), Mauritz, Kenneth A. (committee member).

Subjects/Keywords: fuel cell; semicrystalline ionomer; Nafion; perfluorosulfonic acid ionomer; proton exchange membrane; morphology; processing of elatomers; degradation of elastomers; proton exchange membrane fuel cell; structure-property relationshipe

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APA (6^th Edition):

Divoux, G. M. M. (2012). Properties and Performance of Polymeric Materials Used in Fuel Cell Applications. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/26374

Chicago Manual of Style (16^th Edition):

Divoux, Gilles Michel Marc. “Properties and Performance of Polymeric Materials Used in Fuel Cell Applications.” 2012. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/26374.

MLA Handbook (7^th Edition):

Divoux, Gilles Michel Marc. “Properties and Performance of Polymeric Materials Used in Fuel Cell Applications.” 2012. Web. 07 Mar 2021.

Vancouver:

Divoux GMM. Properties and Performance of Polymeric Materials Used in Fuel Cell Applications. [Internet] [Doctoral dissertation]. Virginia Tech; 2012. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/26374.

Council of Science Editors:

Divoux GMM. Properties and Performance of Polymeric Materials Used in Fuel Cell Applications. [Doctoral Dissertation]. Virginia Tech; 2012. Available from: http://hdl.handle.net/10919/26374

Virginia Tech

25. Smith, Charles E. Intrinsic Quantum Thermodynamics: Application to Hydrogen Storage on a Carbon Nanotube and Theoretical Consideration of Non-Work Interactions.

Degree: PhD, Mechanical Engineering, 2012, Virginia Tech

URL: http://hdl.handle.net/10919/26242

► Intrinsic Quantum Thermodynamics (IQT) is a theory that combines Thermodynamics and Quantum Mechanics into a single theory and asserts that irreversibility and the increase of… (more)

▼ Intrinsic Quantum Thermodynamics (IQT) is a theory that combines Thermodynamics and Quantum Mechanics into a single theory and asserts that irreversibility and the increase of entropy has its origin at the fundamental, atomistic level. The merits and details of IQT are discussed and compared with the well-known theory of Quantum Statistical Mechanics (QSM) and the more recent development of Quantum Thermodynamics (QT). IQT is then used to model in 3D the time evolution of the adsorption of hydrogen on a single-walled carbon nanotube. The initial state of the hydrogen molecules is far from stable equilibrium and over time the system relaxes to a state of stable equilibrium with the hydrogen near the walls of the carbon nanotube. The details of the model are presented, which include the construction of the energy eigenlevels for the system, the treatment of the interactions between the hydrogen and the nanotube along with the interactions of the hydrogen molecules with each other, and the solution of the IQT equation of motion as well as approximation methods that are developed to deal with extremely large numbers of energy eigenlevels. In addition, a new extension to the theory of IQT is proposed for modeling systems that undergo heat interactions with a heat reservoir. The formulation of a new heat interaction operator is discussed, implemented, tested, and compared with a previous version extant in the literature. IQT theory is then further extended to encompass simple mass interactions with a mass reservoir. The formulation, implementation, and testing of the mass interaction operator is also discussed in detail. Finally, IQT is used to model the results of two experiments found in the literature. The first experiment deals with the spin relaxation of rubidium atoms and the second tests the relaxation behavior of single trapped ion that is allowed to interact with an external heat reservoir. Good agreement between experiment and the model predictions is found. Advisors/Committee Members: von Spakovsky, Michael R. (committeechair), Ellis, Michael W. (committee member), Paul, Mark R. (committee member), Huxtable, Scott T. (committee member), Brown, Eugene F. (committee member), Beretta, Gian Paolo (committee member).

Subjects/Keywords: mass; heat interaction; hydrogen storage; quantum thermodynamics; intrinsic quantum thermodynamics

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APA (6^th Edition):

Smith, C. E. (2012). Intrinsic Quantum Thermodynamics: Application to Hydrogen Storage on a Carbon Nanotube and Theoretical Consideration of Non-Work Interactions. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/26242

Chicago Manual of Style (16^th Edition):

Smith, Charles E. “Intrinsic Quantum Thermodynamics: Application to Hydrogen Storage on a Carbon Nanotube and Theoretical Consideration of Non-Work Interactions.” 2012. Doctoral Dissertation, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/26242.

MLA Handbook (7^th Edition):

Smith, Charles E. “Intrinsic Quantum Thermodynamics: Application to Hydrogen Storage on a Carbon Nanotube and Theoretical Consideration of Non-Work Interactions.” 2012. Web. 07 Mar 2021.

Vancouver:

Smith CE. Intrinsic Quantum Thermodynamics: Application to Hydrogen Storage on a Carbon Nanotube and Theoretical Consideration of Non-Work Interactions. [Internet] [Doctoral dissertation]. Virginia Tech; 2012. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/26242.

Council of Science Editors:

Smith CE. Intrinsic Quantum Thermodynamics: Application to Hydrogen Storage on a Carbon Nanotube and Theoretical Consideration of Non-Work Interactions. [Doctoral Dissertation]. Virginia Tech; 2012. Available from: http://hdl.handle.net/10919/26242

Virginia Tech

26. Lamp, Jennifer Lynn. Electrical Power Generation in Microbial Fuel Cells Using Carbon Nanostructure Enhanced Anodes.

Degree: MS, Mechanical Engineering, 2009, Virginia Tech

URL: http://hdl.handle.net/10919/44458

► Microbial fuel cells (MiFCs) have been suggested as a means to harness energy that is otherwise unutilized during the wastewater treatment process. MiFCs have the… (more)

Subjects/Keywords: microbial fuel cell; fuel cell; carbon nanostructures; MiFC; biofilm anode

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APA (6^th Edition):

Lamp, J. L. (2009). Electrical Power Generation in Microbial Fuel Cells Using Carbon Nanostructure Enhanced Anodes. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/44458

Chicago Manual of Style (16^th Edition):

Lamp, Jennifer Lynn. “Electrical Power Generation in Microbial Fuel Cells Using Carbon Nanostructure Enhanced Anodes.” 2009. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/44458.

MLA Handbook (7^th Edition):

Lamp, Jennifer Lynn. “Electrical Power Generation in Microbial Fuel Cells Using Carbon Nanostructure Enhanced Anodes.” 2009. Web. 07 Mar 2021.

Vancouver:

Lamp JL. Electrical Power Generation in Microbial Fuel Cells Using Carbon Nanostructure Enhanced Anodes. [Internet] [Masters thesis]. Virginia Tech; 2009. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/44458.

Council of Science Editors:

Lamp JL. Electrical Power Generation in Microbial Fuel Cells Using Carbon Nanostructure Enhanced Anodes. [Masters Thesis]. Virginia Tech; 2009. Available from: http://hdl.handle.net/10919/44458

Virginia Tech

27. Kruszewski, Eric. Investigation of Graphite Bipolar Plates for PEM Fuel Cell Performance.

Degree: MS, Mechanical Engineering, 2001, Virginia Tech

URL: http://hdl.handle.net/10919/35835

► The largest cost in manufacturing PEM fuel cells for automotive applications is due to the bipolar plate. The current graphite material used for the bipolar… (more)

Subjects/Keywords: Graphite; Fuel Cells; Bipolar Plates; Test Stand

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APA (6^th Edition):

Kruszewski, E. (2001). Investigation of Graphite Bipolar Plates for PEM Fuel Cell Performance. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/35835

Chicago Manual of Style (16^th Edition):

Kruszewski, Eric. “Investigation of Graphite Bipolar Plates for PEM Fuel Cell Performance.” 2001. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/35835.

MLA Handbook (7^th Edition):

Kruszewski, Eric. “Investigation of Graphite Bipolar Plates for PEM Fuel Cell Performance.” 2001. Web. 07 Mar 2021.

Vancouver:

Kruszewski E. Investigation of Graphite Bipolar Plates for PEM Fuel Cell Performance. [Internet] [Masters thesis]. Virginia Tech; 2001. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/35835.

Council of Science Editors:

Kruszewski E. Investigation of Graphite Bipolar Plates for PEM Fuel Cell Performance. [Masters Thesis]. Virginia Tech; 2001. Available from: http://hdl.handle.net/10919/35835

Virginia Tech

28. Henderson, Kenneth Reed. Evaluation of the Effect of Microporous Sublayer Design and Fabrication on Performance and Adhesion in PEM Fuel Cell Assemblies.

Degree: MS, Mechanical Engineering, 2005, Virginia Tech

URL: http://hdl.handle.net/10919/35348

► The typical architecture of the proton exchange membrane fuel cell (PEMFC) contains a layer called the microporous sublayer (MSL). The MSL is a mixture of… (more)

Subjects/Keywords: Water Management Layer; Catalyst Support Layer; Microporous Sublayer; PEMFC; Fuel Cell

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APA (6^th Edition):

Henderson, K. R. (2005). Evaluation of the Effect of Microporous Sublayer Design and Fabrication on Performance and Adhesion in PEM Fuel Cell Assemblies. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/35348

Chicago Manual of Style (16^th Edition):

Henderson, Kenneth Reed. “Evaluation of the Effect of Microporous Sublayer Design and Fabrication on Performance and Adhesion in PEM Fuel Cell Assemblies.” 2005. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/35348.

MLA Handbook (7^th Edition):

Henderson, Kenneth Reed. “Evaluation of the Effect of Microporous Sublayer Design and Fabrication on Performance and Adhesion in PEM Fuel Cell Assemblies.” 2005. Web. 07 Mar 2021.

Vancouver:

Henderson KR. Evaluation of the Effect of Microporous Sublayer Design and Fabrication on Performance and Adhesion in PEM Fuel Cell Assemblies. [Internet] [Masters thesis]. Virginia Tech; 2005. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/35348.

Council of Science Editors:

Henderson KR. Evaluation of the Effect of Microporous Sublayer Design and Fabrication on Performance and Adhesion in PEM Fuel Cell Assemblies. [Masters Thesis]. Virginia Tech; 2005. Available from: http://hdl.handle.net/10919/35348

Virginia Tech

29. Gunes, Mehmet Burak. Investigation of a Fuel Cell Based Total Energy System for Residential Applications.

Degree: MS, Mechanical Engineering, 2001, Virginia Tech

URL: http://hdl.handle.net/10919/32130

► Residences require electricity for lights, appliances, and space cooling and thermal energy for space and domestic water heating. Total energy systems (TES) which provide… (more)

▼ Residences require electricity for lights, appliances, and space cooling and thermal energy for space and domestic water heating. Total energy systems (TES) which provide both electricity and thermal energy can meet these needs more effectively than conventional systems because thermal energy rejected during the on-site production of electricity can be recovered to meet the heating loads. TESs based on fuel cell systems are particularly attractive because of their high efficiencies, quiet operation, and small size. This research evaluates a TES consisting of a fuel cell sub-system (FCS), an electric heat pump (HP), and a thermal storage tank (TS). A model of a grid-independent, electric load following TES is developed to determine the energy required to meet the hourly average electric and thermal loads of the residence. The TES uses a heat pump to provide space cooling. Electricity for air conditioning, lights, and appliances is provided by the FCS. Space heating and water heating of the residence are provided by the thermal energy available from the FCS. The TES is designed so that, heating requirements that exceed the heat available from the FCS can be satisfied by the HP and an electric water heater. A thermal storage tank is used to store and transfer thermal energy from the FCS to the residence. The results of the research include a comparison of the energy use by the TES to the energy use by conventional residential energy systems; an evaluation of the effects of climatic conditions on system performance and energy use; and a comparison of the life-cycle cost of the TES and conventional residential energy systems. The results indicate that total energy systems can reduce primary energy use by as much as 40 percent, but that to be economically attractive, the FCS cost must be reduced to approximately $500/kWe. Advisors/Committee Members: Ellis, Michael W. (committeechair), von Spakovsky, Michael R. (committee member), Nelson, Douglas J. (committee member).

Subjects/Keywords: cogeneration; residential; PEM fuel cell; total energy system

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APA (6^th Edition):

Gunes, M. B. (2001). Investigation of a Fuel Cell Based Total Energy System for Residential Applications. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/32130

Chicago Manual of Style (16^th Edition):

Gunes, Mehmet Burak. “Investigation of a Fuel Cell Based Total Energy System for Residential Applications.” 2001. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/32130.

MLA Handbook (7^th Edition):

Gunes, Mehmet Burak. “Investigation of a Fuel Cell Based Total Energy System for Residential Applications.” 2001. Web. 07 Mar 2021.

Vancouver:

Gunes MB. Investigation of a Fuel Cell Based Total Energy System for Residential Applications. [Internet] [Masters thesis]. Virginia Tech; 2001. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/32130.

Council of Science Editors:

Gunes MB. Investigation of a Fuel Cell Based Total Energy System for Residential Applications. [Masters Thesis]. Virginia Tech; 2001. Available from: http://hdl.handle.net/10919/32130

Virginia Tech

30. Grohs, Jacob R. Analysis and Modeling of the Mechanical Durability of Proton Exchange Membranes Using Pressure-Loaded Blister Tests.

Degree: MS, Engineering Science and Mechanics, 2009, Virginia Tech

URL: http://hdl.handle.net/10919/42180

► Environmental fluctuations in operating fuel cells impose significant biaxial stresses in the constrained proton exchange membranes (PEM). The PEMâ s ability to withstand cyclic environment-induced… (more)

Subjects/Keywords: lifetime prediction model; finite element analysis; digital image correlation; pressure-loaded blister test; proton exchange membrane

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APA (6^th Edition):

Grohs, J. R. (2009). Analysis and Modeling of the Mechanical Durability of Proton Exchange Membranes Using Pressure-Loaded Blister Tests. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/42180

Chicago Manual of Style (16^th Edition):

Grohs, Jacob R. “Analysis and Modeling of the Mechanical Durability of Proton Exchange Membranes Using Pressure-Loaded Blister Tests.” 2009. Masters Thesis, Virginia Tech. Accessed March 07, 2021. http://hdl.handle.net/10919/42180.

MLA Handbook (7^th Edition):

Grohs, Jacob R. “Analysis and Modeling of the Mechanical Durability of Proton Exchange Membranes Using Pressure-Loaded Blister Tests.” 2009. Web. 07 Mar 2021.

Vancouver:

Grohs JR. Analysis and Modeling of the Mechanical Durability of Proton Exchange Membranes Using Pressure-Loaded Blister Tests. [Internet] [Masters thesis]. Virginia Tech; 2009. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10919/42180.

Council of Science Editors:

Grohs JR. Analysis and Modeling of the Mechanical Durability of Proton Exchange Membranes Using Pressure-Loaded Blister Tests. [Masters Thesis]. Virginia Tech; 2009. Available from: http://hdl.handle.net/10919/42180

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