Bostjan Pregelj

A Diesel-Powered Fuel Cell APU—Reliability Issues and Mitigation Approaches

The paper deals with reliability issues of a diesel-powered fuel cell auxiliary power unit (APU). The unit combines an autothermal diesel reformer and a proton exchange membrane fuel cell stack. The focal point is mitigation approaches for increasing the reliability of the complete APU system. These include control strategies on the one side, and electronic hardware solutions on the other. The measures, guarantying safe, reliable, and long-life operation, were developed, implemented and experimentally validated on a 3-kW net electric power APU system targeted for truck on-board applications.

An assessment of water conditions in a PEM fuel cell stack using Electrochemical Impedance Spectroscopy

The success of the fuel-cells technology penetration into commercial applications depends on the fuel-cells-based systems (FCS) durability, reliability and cost competitiveness. One way to improve the FCS durability is usage of advanced diagnostic methods in the context of holistic control. Electrochemical Impedance Spectroscopy (EIS) is for this purpose one of the more promising diagnostic methods because of its non-invasivity and ability to distinguish between the flooding and drying out of the Proton Exchange Membrane (PEM), a key part of each fuel-cell in a stack. Namely, a proper wetness of the stack membranes has an essential impact on the overall fuel cells system performance. This paper deals with the employment of EIS to commercially available PEM FCS. It presents the measuring system, describes EIS methodology, measurements, data processing, calculation procedures and final results.