Fully automatic test facilities for the characterisation of DMFC and PEFC MEAs

Membrane electrode assemblies (MEAs) for polymer electrolyte fuel cells with hydrogen fuel (H-2-PEFC) and direct methanol fuel cells (DMFC) are under development at DLR. For their characterisation fully automatic test units have been designed and realised to guarantee reproducible test results. The identical oxidant supply at the cathode side of the H-2-PEFC and DMFC as well as similar test cells and test conditions offer the possibility to realise both modifications in one test unit. The pipework system and all fittings of the cathode supply can be used simultaneously. Different conditions have to be realised particularly in the anode supply. At the anode of the DMFC liquids (methanol/water) and in the H-2-PEFC gas (hydrogen) are supplied. By integration of an electronic software-supported control unit operating modes can be changed in the test unit depending upon requirement. In order to show the reproducibility of fuel cell operations it is necessary that parameters will be kept within very low deviation limits. An automatic regulation permits impact onto all controllable parameters e.g. pressures, temperatures and mass flow rates. When achieving stationary operating conditions current-voltage-curves can be recorded by automatic change of the electronic cell load. Measured values for current, voltage and all operating parameters are recorded by the software and stored for later interpretation. During data acquisition the parameters are visualised on a graphic interface. It is possible to influence the control at any time. To permit an unguarded long-term experimental operation a sophisticated safety system is necessary. The pre-defined safety parameters are monitored by computer software as well as by an industrial type Programmable Logic Controller (PLC). (C) 2003 Elsevier Science B.V. All rights reserved.