A Comparison of Energy Use for a Direct-Hydrogen Hybrid Versus a Direct-Hydrogen Load-Following Fuel Cell Vehicle

Cunningham, Joshua; Moore, Robert M.; Ramaswamy, Sitaram; Hauer, Karl-Heinz

doi:10.4271/2003-01-0416

Cited by 7 publications

(6 citation statements)

References 5 publications

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“…Air supply control strategies and analyses based on dynamic quasi-steady fuel cell operation are described in [15,[18][19][20][21][22][23]. These studies established a good foundation for understanding fuel cell systems and fuel cell vehicles.…”

Section: Page 3 Of 37mentioning

confidence: 99%

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Optimization of fuel cell system operating conditions for fuel cell vehicles

Zhao

Burke

2009

Journal of Power Sources

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Proton Exchange Membrane fuel cell (PEMFC) technology for use in fuel cell vehicles and other applications has been intensively developed in recent decades. Besides the fuel cell stack, air and fuel control and thermal and water management are major challenges in the development of the fuel cell for vehicle applications. The air supply system can have a major impact on overall system efficiency. In this paper a fuel cell system model for optimizing system operating conditions was developed which includes the transient dynamics of the air system with varying back pressure. Compared to the conventional fixed back pressure operation, the optimal operation discussed in this paper can achieve higher system efficiency over the full load range. Finally, the model is applied as part of a dynamic forward-looking vehicle model of a load-following direct hydrogen fuel cell vehicle to explore the energy economy optimization potential of fuel cell vehicles.

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Section: Page 3 Of 37mentioning

confidence: 99%

“…Fuel cell models at the cell level are presented in [2][3][4]. Studies concerned with optimum operating conditions are discussed in [5][6][7][8][9][10][11][12]. The characteristics of the low pressure and high pressure fuel cell systems are addressed with regard to the system efficiency and transient response in [7,13,14].…”

Section: Introductionmentioning

confidence: 99%

Optimization of fuel cell system operating conditions for fuel cell vehicles

Zhao

Burke

2009

Journal of Power Sources

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“…During the last five years, a tremendous amount of research has been conducted on fuel cell technology, and several new membrane and cell designs have improved the power output per cell significantly. A recently reported fuel cell stack can generate 66.5 kW with 450 cells (148 W/cell) [24]. Figure 9.…”

Section: Resultsmentioning

confidence: 99%

Optimal Design of Hybrid Fuel Cell Vehicles

Han

Kokkolaras

Papalambros

2006

ASME 2006 Fourth International Conference on Fuel Cell Science, Engineering and Technology, Parts a and B

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Fuel cells are being considered increasingly as a viable alternative energy source for automobiles because of their clean and efficient power generation. Numerous technological concepts have been developed and compared in terms of safety, robust operation, fuel economy, and vehicle performance. However, several issues still exist and must be addressed to improve the viability of this emerging technology. Despite the relatively large number of models and prototypes, a model-based vehicle design capability with sufficient fidelity and efficiency is not yet available in the literature. In this article we present an analysis and design optimization model for fuel cell vehicles that can be applied to both hybrid and non-hybrid vehicles by integrating a fuel cell vehicle simulator with a physics-based fuel cell model. The integration is achieved via quasi-steady fuel cell performance maps, and provides the ability to modify the characteristics of fuel cell systems with sufficient accuracy (less than 5% error) and efficiency (98% computational time reduction on average). Thus, a vehicle can be optimized subject to constraints that include various performance metrics and design specifications so that the overall efficiency of the hybrid fuel cell vehicle can be improved by 14% without violating any constraints. The obtained optimal fuel cell system is also compared to other, not vehicle-related, fuel cell systems optimized for maximum power density or maximum efficiency. A tradeoff between power density and efficiency can be observed depending on the size of compressors. Typically, a larger compressor results in higher fuel cell power density at the cost of fuel cell efficiency because it operates in a wider current region. When optimizing the fuel cell * Corresponding author, Phone/Fax: (734) 647-8402/8403 system for maximum power density, we observe that the optimal compressor operates efficiently. When optimizing the fuel cell system to be used as a power source in a vehicle, the optimal compressor is smaller and less efficient than the one of the fuel cell system optimized for maximum power density. In spite of this compressor inefficiency, the fuel cell system is 9% more efficient on average. In addition, vehicle performance can be improved significantly because the fuel cell system is designed both for maximum power density and efficiency. For a more comprehensive understanding of the overall design tradeoffs, several constraints dealing with cost, weight, and packaging issues must be considered. IntroductionCurrently, PEM fuel cells are agreed upon as the most suitable technology for vehicular applications because of their mobility and high power density [1]. Nevertheless, several issues still exist that must be addressed in order to assess and improve viability of fuel cell vehicles, including high vs. low pressure fuel cell vehicles and hybrid vs. non-hybrid fuel cell vehicles. Several fuel cell vehicle concepts and fuel cell system designs have been proposed and studied in terms of safety, robust opera...

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“…The FCV model is a fully dynamic forward-looking model 1 with associated control strategies (at the component and system level) for efficient operation and good dynamic response. Time traces of all system and component variables are available for each driving cycle, as well as aggregate metrics, through a graphical user interface (GUI).…”

Section: General Model Descriptionsmentioning

confidence: 99%

“…The focus of this report is on the indirect hydrocarbon vehicle platform only. The direct hydrogen platform has been investigated separately in a companion paper [1,Cunningham]. The vehicle energy use and efficiency are compared between the original load following vehicle and the new hybrid vehicle platform.…”

Section: Introductionmentioning

confidence: 99%

A Comparison of Energy Use for a Indirect-Hydrocarbon Hybrid versus an Indirect-Hydrocarbon Load-Following Fuel Cell Vehicle

Ramaswamy

Moore

Cunningham

et al. 2004

SAE Technical Paper Series

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Hybrid vehicles have been in the news quite a bit of late given the commercial introduction of a number of hybrid vehicles that sport significant improvements in fuel economy. The improved fuel efficiency of these vehicles can be directly attributable to the hybridized power train on board these internal combustion engine vehicles. Similarly, hybridization of fuel cell vehicles not only helps improve fuel economy but can also help overcome other technical barriers (start up delays, transients). For fuel cell vehicles, hybridization of on-board fuel cell systems is expected to have the potential to improve the vehicle efficiency largely due to the ability to recover braking energy and via flexibility in designing the system controls. However, the advantages can be offset by the tradeoffs due to added energy losses associated with the DC/DC converter and the battery pack itself. Additional tradeoffs not explicitly addressed in this study include added overall complexity, additional packaging constraints, and potentially higher overall cost. This report will focus on a quantitative analysis of the performance of the indirect-hydrocarbon (IH, onboard fuel processor using gasoline type fuel), hybrid and loadfollowing fuel cell vehicles (FCVs) from the viewpoint of the energy use throughout the system. Specifically, the vehicle energy use and efficiency will be compared between the load following (non-hybrid) and hybrid vehicle platforms. Several hybrid component configurations were studied and two representative configurations were investigated in depth. The first (Configuration 1), in which the DC/DC converter is placed in the path of the fuel cell stack current, there does appear to be some benefit, in terms of energy usage, in hybridizing the IH fuel cell vehicle. Specifically, on the US EPA cycles, the hybrid vehicle outperformed the load following vehicle on the FUDS sequence but the load following vehicle had slightly better results on the HIWAY cycle. However, if the DC/DC converter is placed in the battery current path only, with the fuel cell stack directly connected to the electric drive train (Configuration 2), the benefits in terms of improved fuel economy are larger than in the first configuration. The results corresponding to both these configurations will be analyzed and discussed in this paper. Overall, three main factors affect these vehicle results, all of which will be explicitly examined in this study. These factors are: vehicle weight, fuel cell system efficiency (including the battery), and regenerative braking capabilities. Specifically, the hybrid vehicle fuel economy can be reduced due to a ~10% heavier vehicle, and a lower overall fuel cell system efficiency (when including the battery and DC/DC converter losses). One important factor is clearly the regenerative braking capability; but the other factor is associated with the ability to improve the efficiency of the fuel cell system itself by taking advantage of the flexibility offered energy storage subsystem and adopting better control strat...

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A Comparison of Energy Use for a Direct-Hydrogen Hybrid Versus a Direct-Hydrogen Load-Following Fuel Cell Vehicle

Cited by 7 publications

References 5 publications

Optimization of fuel cell system operating conditions for fuel cell vehicles

Optimization of fuel cell system operating conditions for fuel cell vehicles

Optimal Design of Hybrid Fuel Cell Vehicles

A Comparison of Energy Use for a Indirect-Hydrocarbon Hybrid versus an Indirect-Hydrocarbon Load-Following Fuel Cell Vehicle

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