EU HARMONISED TEST PROTOCOLS FOR PEMFC MEA TESTING IN SINGLE CELL CONFIGURATION FOR AUTOMOTIVE APPLICATIONS

摘要

PEMFC due to their high energy density, low operating temperature and high efficiency are considered to be very suitable for vehicle propulsion. In such applications, fuel cells could encounter operating conditions which are severe to the materials involved. Fuel cell testing shall as close as possible reflect conditions encountered in real life. To enable a fair comparative assessment of the performance of MEA under operating conditions foreseen in future automotive applications, a set of representative operating conditions in addition with a test methodology is proposed. The aim of a unified set of harmonised operating conditions is to comparatively test and evaluate the performance of different MEAs in single cells. The current document is the result of a cumulative effort of industry and research organisations participating in FCH-JU funded projects for automotive applications, in establishing a harmonised test protocol for assessing PEMFC performance and durability at a single cell level. This document presents a set of reference operating conditions such as temperature, pressure, humidification, gas flow and composition at the fuel and oxidant inlet representative for future automotive applications. It also defines boundaries of these conditions within which the cell is expected to operate. While not specifying single cell design details, cell operation in counter flow is mandatory for comparative assessment. A methodology is established to examining the relative influence that the individual operating parameters exert on the MEA performance in single cell configuration once the cell is subjected to the more challenging boundary conditions defined in this document which are also called as stressor conditions. In addition to operating conditions, the most likely stressor conditions for single cell testing could be identified as follows: Load cycling, Mechanical effects, Fuel Air contaminants (impurities), and Environmental Conditions. In this document the focus is on stressors related to Operating Conditions and Load Cycling. Deviations from the automotive reference Operating Conditions may result in changes to both cell performance and durability. In principle the influence of each stressor on cell performance could be studied individually. However, since a number of stressors are inter-linked, (changing the value of one stressor could inevitably change the value of another), the stressor tests have been grouped into four families of Stressors, namely: Cell Temperature Stressor Tests, Reactants Gas Inlet Humidification Stressor Tests, Reactants Gas Inlet Pressure Stressor Tests, Oxidant Stoichiometry Stressor Tests. The aim of these tests is to study the effect of each stressor on the the cell voltage at three different current densities representative of activation, ohmic polarization and mass transfer regimes as a function of each stressor condition. The successful operation of a fuel cell depends not only on its performance but also on its durability. Fuel cell durability is evaluated through endurance testing by applying a repetitive load profile to the cell and measuring performance degradation in terms of cell voltage decrease as function of operating hours. To assess the cell degradation rate a dynamic load cycle for endurance testing is proposed. The Fuel Cell Dynamic Load Cycle is used in this document and is derived from the New European Driving Cycle modified for fuel cell applications. In addition to the definition of representative reference and stressor operating conditions, the document also provides a rationale for their selection. The use of sound science-based, industry-endorsed test methodologies and protocols enables true comparison of MEAs originating from different sources either commercial or developed within different projects. It also enables evaluating the rate of progress achieved towards reaching agreed technology performance targets.