关键词: 燃料电池电堆, 乙二醇污染, 恢复策略, 污染物氧化和冲洗

Abstract:

As the heat conduction medium of fuel cell cooling system, coolant is very important for the thermal management of fuel cell stack. In practical application, coolant leakage into the stack often occurs. Due to the randomness of fault location of components, the location of coolant leakage is uncertain, which may occur on the cathode side or anode side of some or all single cells. The main effects of coolant pollution on fuel cell stack are as follows: the output of open circuit voltage decreases sharply, the consistency of single cells voltage decreases and so on, which seriously affects the normal use of fuel cell engine. It is very important to study the effect of glycol based coolant leakage on the performance of fuel cell stack and the pollution mitigation measures to improve the service life of fuel cell stack and reduce the maintenance cost. It was found that the open circuit voltage of the single cell polluted by glycol based coolant decreased to less than 0.8 V. Meanwhile, it was also found that the effect of coolant pollution on the cell performance was small and could be gradually restored with the current loading. When the anode side and cathode side are polluted by coolant at the same time, it has the greatest impact on the stack performance and even causes reverse polarity phenomenon. The performance influenced by cathode side coolant contamination is not easy to be recovered. Aiming at the problem that it is difficult to recover after cathode side glycol based coolant contamination, this paper proposes a recovery strategy of coolant contamination. The whole recovery strategy is divided into two stages: pollutant oxidation and pollutant flushing. In the first stage, the coolant contamination was oxidized under high humidity and high potential, and the catalytic activity of Pt based catalyst was recovered; In the second stage, the membrane electrode assembly and bipolar plate were cleaned and washed under the conditions of high humidity, high gas flow and high water yield, and the pollutants after oxidation were discharged. Finally, the performance of single cell after coolant pollution was restored by comparing the performance of single cell before and after coolant pollution. The results show that the strategy is effective. The fuel cell stack after pollution recovery can be used normally, which greatly saves time, cost of material replacement and stack disassembly in the process of stack maintenance.

Key words: fuel cell stack, ethylene glycol contamination, recovery strategy, contamination oxidation and flushing