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A detailed simulation of a load-following indirect methanol fuel cell (IMFC) system was performed by the University of California - Davis fuel cell vehicle modeling program (FCVMP) in order to determine the realistic steady-state and dynamic performance of such a system. The first part of the paper includes a basic description of the model and the control of the system. The interaction between the fuel processor and the anode side of the stack is shown to have dynamic load following limitations and a subsequent control strategy is described to solve this problem. The interaction between the air supply, the cathode side of the stack and the water recovery is shown to have several optimization opportunities. In the second part of the paper, we find that the steady state efficiency of the system peaks at approximately 52% at around 5% of full power. The 25% of full power steady-state system efficiency is approximately 45% and the full power efficiency is approximately 27%.

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.

Fuel cell vehicles powered using Hydrogen/air fuel cells have received a lot of attention recently as possible alternatives to internal combustion engine. However, the combined problems of on-board Hydrogen storage and the lack of Hydrogen infrastructure represent major impediments to their wide scale adoption as replacements for IC engine vehicles. On board fuel processors that generate hydrogen from on-board liquid methanol (and other hydrocarbons) have been proposed as possible alternative sources of Hydrogen needed by the fuel cell. This paper focuses on a methanol fuel processor using steam reformation of methanol to generate the Hydrogen required for the fuel cell stack. Since the steam reformation is an endothermic process the thermal energy required is supplied by a catalytic burner.

Hybridizing a fuel cell vehicle has the potential to improve the vehicle efficiency largely due to the ability to recover braking energy. However, tradeoffs do exist, and the advantages (in terms of potential fuel savings) are largely dependent on the drive cycle. The tradeoffs include 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 direct-hydrogen (DH) hybrid and load-following 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 and hybrid vehicle platforms. Several hybrid component configurations were studied.

This paper primarily compares costs and fuel economies of load following direct-hydrogen fuel cell vehicles with battery hybrid variations of the same vehicle. Additional information is included regarding load-following indirect methanol fuel cell vehicles. The key points addressed are as follows: the tradeoff between fuel cell system efficiency and regenerative braking ability; transient effects; and component cost differences. The difference in energy use and costs can vary significantly depending on the assumptions and the hybrid configurations. The mass of the battery pack creates the largest impact in energy use, while system efficiency losses roughly balance out with regenerative braking. For the direct-hydrogen fuel cell system, transient effects are small. These effects are expected to be significant for steam reformer/indirect-methanol systems (analyzed only graphically herein).

This paper deals with system level analysis of a methanol fuel processor for an indirect hydrogen-Air based Fuel Cell Vehicle (FCV) based on a Proton Exchange Membrane (PEM) fuel cell stack. This analysis focuses on the performance of the fuel processor from the viewpoint of efficiency and the requirements placed on it by the Fuel Cell Vehicle. It is widely accepted that hydrogen supply is an important issue in PEM-FC vehicle systems. The lack of a well-entrenched hydrogen infrastructure and the nascent state of hydrogen storage technology has led to development of on-board hydrogen generation systems to meet the fuel cell hydrogen demand. The primary fuel is typically a Hydrocarbon (methanol, gasoline) which is then “reformed” in a fuel processor to generate the hydrogen needed by the fuel cell stack. A great deal of effort has been expended in developing fuel processors that would satisfy the rigorous demands of automotive applications.