Fuel Processor for an Indirect Methanol Fuel Cell Vehicle 2000-01-3111

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. There are severe constraints from the viewpoint of volume, weight, cost, response times, fuel reformate CO cleanup and efficiencies. Conventional fuel processor designs have proven to be unsuitable for FCV applications and recent developments have pointed the way towards some advanced fuel processor designs that have a better chance of meeting the challenges posed by FCV applications.

This paper focuses on the modeling of a fuel processor that uses the steam reformation of methanol for hydrogen generation. The salient feature of the fuel processor is the close thermal integration between the Reformer and the Burner (which supplies the endothermic heat requirement of the steam reformation process). The thrust of the paper is on illustrating the performance of the fuel processor under steady state and transient load conditions and identifying design and control strategies for enhancing the performance of the fuel processor in the context of its use in a fuel cell vehicle. This will not explicitly address the issues relating to on-board fuel processor emissions which is the focus of a separate paper. This involves the use of an in-house fuel processor model and the use of the UC Davis Fuel Cell Vehicle Simulator (FCVSim). The model results illustrate the challenges associated with developing fuel processors for fuel cell vehicles and suggest possible approaches for meeting the performance goals of efficiency, short startup times and adequate transient response.