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33 results on '"Fly, Ashley"'

3. Durability Oriented Fuel Cell Electric Vehicle Energy Management Strategies Based on Vehicle Drive Cycles.

Author

Fu, Xin, Fan, Zengbin, Jiang, Shangfeng, Fly, Ashley, Chen, Rui, Han, Yong, and Xie, An

Subjects
CELLULAR aging, FUEL cells, LITHIUM cells, ENERGY management, MOTOR vehicle driving, ELECTRIC vehicle batteries, FUEL cell vehicles, HYBRID electric vehicles
Abstract

With the increasing severity of environmental problems and energy scarcity, fuel cell electric vehicles (FCEVs), as a sustainable and efficient means of transportation, are attracting more attention. The ageing of fuel cells (FCs) has become an urgent problem with the development of FCEV. In order to prolong the lifetime of FCs, this paper builds a model of a vehicle driven by two power sources, FC and lithium battery (Lib) using AVL Cruise. A rule-based energy management strategy (EMS) is developed in Simulink to explore the optimal control strategy for the vehicle in terms of the durability of the FC. An FC ageing model is used to quantify the degradation voltage of different duty cycles. The results show that the FC engagement levels, OCV operations, and start/stop operations can affect the lifetime of the FC significantly. By optimising the EMS, the lifetime of the FC is improved by 9.47%. [ABSTRACT FROM AUTHOR]

Published
2024
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5. Thermal and water management of evaporatively cooled fuel cell vehicles

Author

Fly, Ashley

Subjects
621.31, Fuel cell, PEM, PEMFC, Thermal management, Evaporative cooling
Abstract

Proton Exchange Membrane Fuel Cells (PEMFCs) present a promising alternative to the conventional internal combustion engine for automotive applications because of zero harmful exhaust emissions, fast refuelling times and possibility to be powered by hydrogen generated through renewable energy. However, several issues need to be addressed before the widespread adoption of PEMFCs, one such problem is the removal of waste heat from the fuel cell electrochemical reaction at high ambient temperatures. Automotive scale fuel cells are most commonly liquid cooled, evaporative cooling is an alternative cooling method where liquid water is added directly into the fuel cell flow channels. The liquid water evaporates within the flow channel, both cooling and humidifying the cell. The evaporated water, along with some of the product water, is then condensed from the fuel cell exhaust, stored, and re-used in cooling the fuel cell. This work produces a system level model of an evaporatively cooled fuel cell vehicle suitable for the study of water balance and heat exchanger requirements across steady state operation and transient drive cycles. Modelling results demonstrate the ability of evaporatively cooled fuel cells to self regulate temperature within a narrow region (±2°C) across a wide operating range, provided humidity is maintained within the flow channels through sufficient liquid water addition. The heat exchanger requirements to maintain a self sufficient water supply are investigated, demonstrating that overall heat exchange area can be reduced up to 40% compared to a liquid cooled system due to the presence of phase change within the vehicle radiator improving heat transfer coefficients. For evaporative cooling to remain beneficial in terms of heat exchange area, over 90% of the condensed liquid water needs to be extracted from the exhaust stream. Experimental tests are conducted to investigate the condensation of water vapour from a saturated air stream in a compact plate heat exchanger with chevron flow enhancements. Thermocouples placed within the condensing flow allow the local heat transfer coefficient to be determined and an empirical correlation obtained. The corresponding correlation is used to produce a heat exchanger model and study the influence different heat exchanger layouts have on the overall required heat transfer area for an evaporatively cooled fuel cell vehicle. A one-dimensional, non-isothermal model is also developed to study the distribution of species, current density and temperature along the flow channel of an evaporatively cooled fuel cell using different methods of liquid water addition. Results show that good performance can be achieved with cathode inlet humidities as low as 20%, although some anode liquid water addition may be required at high current densities due to increased electro-osmotic drag. It is also demonstrated that both good membrane hydration and temperature regulation can be managed by uniform addition of liquid water across the cell to maintain a target exhaust relative humidity.

Published
2015

9. A Critical Review on Battery Aging and State Estimation Technologies of Lithium-Ion Batteries: Prospects and Issues

Author

Roy, Probir Kumar, Shahjalal, Mohammad, Shams, Tamanna, Fly, Ashley, Stoyanov, Stoyan, Ahsan, Mominul, Haider, Julfikar, Roy, Probir Kumar, Shahjalal, Mohammad, Shams, Tamanna, Fly, Ashley, Stoyanov, Stoyan, Ahsan, Mominul, and Haider, Julfikar

Abstract

Electric vehicles (EVs) have had a meteoric rise in acceptance in recent decades due to mounting worries about greenhouse gas emissions, global warming, and the depletion of fossil resource supplies because of their superior efficiency and performance. EVs have now gained widespread acceptance in the automobile industry as the most viable alternative for decreasing CO2 production. The battery is an integral ingredient of electric vehicles, and the battery management system (BMS) acts as a bridge between them. The goal of this work is to give a brief review of certain key BMS technologies, including state estimation, aging characterization methodologies, and the aging process. The consequences of battery aging limit its capacity and arise whether the battery is used or not, which is a significant downside in real-world operation. That is why this paper presents a wide range of recent research on Li-ion battery aging processes, including estimations from multiple areas. Afterward, various battery state indicators are thoroughly explained. This work will assist in defining new relevant domains and constructing commercial models and play a critical role in future research in this expanding area by providing a clear picture of the present status of estimating techniques of the major state indicators of Li-ion batteries.

Published
2023

17. Adaptive Piecewise Equivalent Circuit Model With SOC/SOH Estimation Based on Extended Kalman Filter

Author

Huang, Zexin, Best, Matt, Knowles, James, and Fly, Ashley

Abstract

Battery modelling plays a critical role in battery management tasks. A model that provides accurate estimations of state of charge and state of heath in varying operating conditions could significantly improve the performance of battery management systems. Departing from existing literature, this paper presents a self-adaptive Piecewise Equivalent Circuit Model (PECM) based on Extended Kalman Filter (EKF). While traditional Equivalent Circuit Models (ECM) are typically parameterized and validated for a specific range of working conditions (temperature, current and etc.), PECM is able to adapt itself to any working condition in real time. Established in the form of a combination of linear and nonlinear piecewise functions, the model parameters are continuously adjusted based on the measurement of voltage, current, and temperature. Another advantage of PECM is it does not require any prior tests in the lab, for example the Open Circuit Voltage (OCV) test which is time consuming and needs to be calibrated when aged. PECM is accurate, flexible and efficient. It has been validated for different battery chemistries, duty cycles, and temperatures. Furthermore, PECM comes with the State of Charge (SOC) and State of Health (SOH) estimation, which is shown in the model validation process and the degradation study. The results demonstrate that the piecewise parameter adaptation proposed in this paper can be applied to a range of different battery chemistries and at different aged states.

Published
2023
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28. Getting Kids More Active.

Author

Fly, Ashley and Sigars, Cassidy

Abstract

The article focuses on the increasing rate of obesity in children and offers programs to reduce it including "The Walking School Bus," "Run for Life," and other activities scheduled before and after school. It reports that "The Walking School Bus" program which includes a group of students walking to school with an adult helps them to keep healthy and also reduce traffic. It also discusses the before and after school programs that includes activities like Frisbee, golf and tennis.

Published
2011

33. A Fast Activation Energy Derivation (FAED) approach for Lumped Single Particle model in lithium-ion battery module-level heat generation prediction.

Author

He, Haosong, Chen, Xiangjie, Fly, Ashley, and Saini, Vishal

Subjects
*ACTIVATION energy, *ELECTRIC vehicle batteries, *LITHIUM cells, *THERMAL analysis, *BATTERY management systems, *ELECTRIC vehicles
Abstract

The performance of electric vehicles (EVs) heavily relies on the durability and longevity of lithium-ion cells, which are strongly affected by operating temperatures. Various electrochemical models have been developed to investigate the impact of operating temperature on the dynamic heat generation at cell level. Among these, the Lumped Single Particle (LSP) model stands out due to its lower computational cost and higher accuracy under > 1 C-rates. However, key electrochemical parameters (i.e. the ohmic overpotential, exchange current, and diffusion time constant) in the LSP model are temperature-sensitive, requiring Arrhenius dependencies. Conventional activation energy measuring approaches, relying on testing under discrete fixed temperatures to obtain activation energies, are time-consuming. To address this, this paper proposes a FAED approach that fits the temperature-sensitive parameters and corresponding activation energies to experimental data with a single discharge process, reducing the testing time to a minimum of one hour. This approach was experimentally validated on a Tesla battery module (74P6S), demonstrating a good agreement between simulation and experimental results up to 1.5 C-rates, ranging from 16 ℃ to 46 ℃. Furthermore, this approach is suitable for cells with different lithium chemistries, formats, and properties, making it an effective method for thermal analysis of EV packs. • A novel Fast Activation Energy Derivation (FAED) approach is proposed in this paper. • Reduce activation energy measurement time to 1 h. • Suitable for module level test for EVs. • Experimental verification on a TESLA Model S battery module. [ABSTRACT FROM AUTHOR]

Published
2023
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