TRANSIENT POWER LOAD MEASUREMENT OF A SMALL SCALE ELECTRICAL AUTOMOTIVE ENGINE POWERED BY A PROTON EXCHANGE MEMBRANE FUEL CELL STACK

The aim of this research is to analyze the behaviour and the performance of a proton exchange membrane fuel cell (PEM FC) when transient power loads are applied. This paper presents a small scale test platform and reports some experiments to verify the response of the system. The test equipment includes a 150W self breathing and self humidified fuel cell stack, a DC motor and a brake. The hydrogen feed is supplied by means of a pressurized bottle. The cell was forced to follow a standard urban load cycle and we measured its performance and average efficiency. We report an average efficiency of 39% over the entire cycle on the basis of the high heating vale (HHV) and we observed a good response to fast load commutations. The main problem of the self breathing fuel cells is oxygen starvation when the current reaches high values. In order to overcome this problem a control strategy of the cooling fans has been set up: it is suitable to regulate appropriately both the temperature of the stack and the oxygen needs at the cathode. This allows to overcome the problem without the introduction of a compressor and therefore enables to maximize the entire system efficiency.