Download or read book PEM Fuel Cell Low Flow Rate Diagnostics written by Amir Masoud Niroumand and published by . This book was released on 2009 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt: Efficient, reliable, and durable operation of Polymer Electrolyte Membrane (PEM) fuel cells are key requirements for their successful commercialization. One way to achieve this is to use diagnostic tools that can be used during product development and operation to satisfy these requirements. Such diagnostic tools are introduced in this thesis. We introduce the ratio between call voltage and cathode output pressure oscillations as a diagnostic tool for the PEM fuel cell cathode. We show that for our system, these oscillations have similar frequency. Therefore, we propose using the amplitude ratio and phase difference between these oscillations to understand fundamental processes in PEM fuel cells. We use the measure introduced above to design a signal based Fault Detection & Isolation (FDI) algorithm to isolate anode and cathode low flow induced faults during operation. We show that cathode flooding corresponds with an increase in the amplitude of voltage oscillations. Cathode starvation occurs at a cathode stoichiometry that is a second order function of the fuel cell current density for our system, while anode starvation occurs at a fixed anode stoichiometry. We use these measures to design diagnostic residuals, along with a boolean diagnostic logic, to isolate the low flow induced faults. We then examine the robustness of the proposed algorithm to changes in current, pressure, temperature, and humidity operating conditions. Finally, we introduce a sensory vessel capable of measuring the two phase flow as it exits the fuel cell. Using this vessel, we detect two different modes of liquid water retention from the cathode. The first mode is periodic and imposes similar oscillations on the fuel cell voltage, while the second mode corresponds with a spike in the cell voltage. We conclude that the source of the first liquid water is in the Gas Diffusion Layer (GDL) and catalyst pores, while the second sources is in the cathode flow field. The pressure-voltage oscillations and sensory vessel are diagnostic tools that can be used to provide fundamental understanding of processes in PEM fuel cells, while the FDI algorithm can be used during operation to improve system performance, reliability, and lifetime.