| Abstrakt: |
Durability still represents one of the major barriers to the commercialization of Proton Exchange Membrane Fuel Cells (PEMFCs) in the market. Therefore, it is important to understand the main phenomena involving the long-term operation of PEMFCs in order to elucidate the degradation issues of these devices. Thus, in this work long-term experiments of 500 hours at steady state were performed with variations of the operational parameters such as relative humidity, cell temperature and the reactant flow rates. According to the results obtained, the test which presented the lowest global loss of performance (132uV.h-1, with reversible and irreversible losses measured all together) was the one with the temperatures of the humidifiers and cell set all at 75degC and the reactants flow rates set as 300 ml.min-1 and 200 ml.min-1 for the H2 and O2, respectively. For this test, the irreversible loss of performance was assessed as 38uV.h-1. On the other hand, the test performed with higher humidification degree presented much higher global and irreversible losses of performance (318 and 52uV.h-1, respectively), showing that the degree of humidification, which is a function of the operational parameters, strongly influence on the long-term performance. Therefore, the water management is a key point to obtain better performances in long-term operation of PEMFCs. |
