Engineering Commons^™

Low-Fidelity Design Optimization And Parameter Sensitivity Analysis Of Tilt-Rotor Evtol Electric Propulsion Systems, Tyler Critchfield, Andrew Ning

Faculty Publications

Urban air mobility requires a multidisciplinary approach to tackle the important chal- lenges facing the design of these aircraft. This work uses low-to-mid fidelity tools to model rotor aerodynamics, blade structures, vehicle aerodynamics, and electric propulsion for a tilt-rotor electric vertical takeoff and landing (eVTOL) aircraft. We use gradient-based design optimization and extensive parameter sensitivity analysis to explore the design space and complex tradeoffs of tilt-rotor distributed electric propulsion systems.

Triggering Thermal Runaway In Lithium-Ion Batteries, Chris John

Honors Scholar Theses

The proliferation of lithium-ion batteries enables electric devices such as cell phones to electric vehicles to become a reality. A latent danger, however, exists in these batteries. Mechanical, thermal, or electrical damage can initiate a phenomenon known as thermal runaway (TR). This damage causes internal short circuits within the battery, releasing heat and triggering exothermic decomposition reactions. The battery will catch fire if rapid cooling is not present. While experimental designs exist for evaluating TR, significant safety hazards and impracticality may impede testing efforts. Finite element analysis, therefore, becomes a vital tool in modeling TR and mitigation techniques. However, there …

Transient Analysis Of Diffusion-Induced Deformation In A Viscoelastic Electrode, Yaohong Suo, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

In this study, we analyze the transient diffuse-induced-deformation of an electrode consisting of the conducting polymer polypyrrole (PPY) by using the theories of linear viscoelasticity and diffusion-induced stress. We consider two constitutive relationships with dependence of viscosity on strain rate: Kelvin-Voigt model and three-parameter solid model. A numerical method is used to solve the problem of one-dimensional, transient diffusion-induced-deformation under potentiostatic operation. The numerical results reveal that the maximum displacement occurs at the free surface and the maximum stress occurs at the fixed end. The inertia term causes the stress to increase at the onset of lithiation. The stress decreases …

Battery Technologies For Mass Deployment Of Electric Vehicles, Florida Solar Energy Center, R. Paul Brooker

FSEC Energy Research Center®

Electric vehicle (EV) batteries have significantly improved since their inception. However, lifetime of these batteries is still strongly dependent on the usage profiles. This report describes aspects of EV battery utilization, and their impact on battery lifetime. Additionally, this report will describe potential future uses of EV batteries, particularly in vehicle-to-grid applications.

Electric Vehicle Battery Durability And Reliability Under Electric Utility Grid Operations, Florida Solar Energy Center, Matthieu Dubarry

FSEC Energy Research Center®

Battery degradation is extremely important to EV technologies and is a function of several factors, such as electrode chemistries, operating temperatures, and usage profiles (i.e. vehicle-only vs. vehicle-to-grid (V2G) applications). The goal of this research was to assess such impact. Laboratory testing of commercial "18650" Li-ion cells was conducted in Hawaii Natural Energy Institute's Battery Testing Laboratory. The battery test plan used two separate experiments: a cycling experiment to assess the impact of both V2G and grid-to-vehicle (G2V) charging strategies and a calendar aging experiment to assess the impact of temperature and State of Charge (SOC). The results have shown …

Electric Vehicle Life Cycle Cost Assessment, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

The Electric Vehicle Transportation Center (EVTC) has developed a life cycle cost (LCC) model to include all reasonable costs associated with vehicle ownership over a 5, 10, 15, or 20-year period. The EVTC LCC model compares ownership costs of conventional vehicles to plug-in hybrid and battery electric vehicles. Internal combustion engines using gasoline, ethanol, or diesel are considered. The analysis includes costs for tires, insurance and maintenance, federal incentives, state tax, dealership fee, and financed interest payments. Traction battery replacement costs are difficult to ascertain yet are included to investigate their impact on overall life cycle costs. Economic factors used …

Cyclic Durability Of A Solid Oxide Fe-Air Redox Battery Operated At 650°C, Xuan Zhao, Yunhui Gong, Xue Li, Nansheng Xu, Kevin Huang

Faculty Publications

The recently developed rechargeable solid oxide metal-air redox battery has shown a great potential for applications in mid- to large-scale stationary energy storage. Cyclic durability is one of the most important requirements for stationary energy storage. In this study, we report the cyclic durability of a solid oxide Fe-air redox battery operated at 650◦C. The battery was continuously cycled 100 times under a current density of 50 mA/cm2 with rather flat performance, producing an average specific energy of 760 Wh/kg-Fe at a round-trip efficiency of 55.5%. The post-test examination indicated that the performance losses could arise from the fuel-electrode of …

Anisotropic Compositional Expansion And Chemical Potential For Amorphous Lithiated Silicon Under Stress Tensor, Valery I. Levitas, Hamed Attariani

Mechanical and Materials Engineering Faculty Publications

Si is a promising anode material for Li-ion batteries, since it absorbs large amounts of Li. However, insertion of Li leads to 334% of volumetric expansion, huge stresses, and fracture; it can be suppressed by utilizing nanoscale anode structures. Continuum approaches to stress relaxation in Li_xSi, based on plasticity theory, are unrealistic, because the yield strength of Li_xSi is much higher than the generated stresses. Here, we suggest that stress relaxation is due to anisotropic (tensorial) compositional straining that occurs during insertion-extraction at any deviatoric stresses. Developed theory describes known experimental and atomistic simulation …

Solid State Aircraft Concept Overview, M. Shahinpoor, P. Jenkins, C. Smith, Kakkattukuzhy M. Isaac, T. Dalbello, Anthony Colozza

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Due to recent advances in polymers, photovoltaics, and batteries a unique type of aircraft may be feasible. This is a "solid-state" aircraft, with no conventional mechanical moving parts. Airfoil, propulsion, energy production, energy storage and control are combined in an integrated structure. The key material of this concept is an ionic polymeric-metal composite (IPMC) that provides source of control and propulsion. This material has the unique capability of deforming in an electric field and returning to its original shape when the field is removed. Combining the IPMC with thin-film batteries and thin-film photovoltaics provides both energy source and storage in …

Recommendations For Maximizing Battery Life In Photovoltaic Systems: A Review Of The Lessons Learned, Florida Solar Energy Center, James Dunlop

FSEC Energy Research Center®

This report contains notes, observations and recommendations about the use of batteries in small stand-alone photovoltaic (PV) systems. The conclusions of this work are based on the results of more than a decade's worth of battery testing at the Florida Solar Energy Center and related work with Sandia National Laboratories, the PV industry and user groups. The most critical findings were the relationship between battery state-of-charge and battery life and the importance of an adequate PV array-to-load ratio.

Pv Lighting Systems For Bcc - Evaluation Of Vrla Batteries And Pwm Controls, Florida Solar Energy Center, James Dunlop

FSEC Energy Research Center®

This report presents the initial seven-month performance summary for these 15 PV lighting systems, for the period February 13 through September 15, 1997. During this time, the systems were configured with three types of valve-regulated lead acid (VRLA) batteries (five systems using each type of battery), all operating with pulse-width-modulated (PWM) battery charge controllers. Details of the system configurations are presented in this report. Prior to initial operation, extensive baseline data was collected on the individual components installed in each system. This data included battery capacity and high-rate load measurements, battery weights, charge controller set points, PV array currents and …

Batteries And Charge Control In Stand-Alone Photovoltaic Systems, Florida Solar Energy Center, James Dunlop

FSEC Energy Research Center®

This report presents fundamentals of battery technology and charge control strategies commonly used in stand-alone photovoltaic (PV) systems. This work is a compilation of information from several sources, including PV system design manuals, research reports and data from component manufacturers.

Details are provided about the common types of flooded lead-acid, valve regulated lead-acid, and nickel cadmium cells used in PV systems, including their design and construction, electrochemistry and operational performance characteristics. Comparisons are given for various battery technologies, and considerations for battery subsystem design, auxiliary systems, maintenance and safety are discussed.

Requirements for battery charge control in stand-alone PV systems …

Batteries And Charge Control In Stand-Alone Photovoltaic Systems. Fundamental And Application, Florida Solar Energy Center, James Dunlop

FSEC Energy Research Center®

This report presents an overview of battery technology and charge control strategies commonly used in stand-alone photovoltaic (PV) systems. This work is a compilation of information from several sources, including PV system design manuals, research reports, data from component manufacturers, and lessons learned from hardware evaluations.