This research describes how residual water taken-up in Nafion membrane is removed more effectively by a pulsating gas flow than by a constant gas flow. Generally, residual water in the membrane should be removed mostly to start up in a subzero condition since ice formed in that condition can plug pores of the catalyst layer so that fuel cannot be supplied properly. Therefore, purge process is needed to dry out the membrane and help a proper cold start. However, it is predicted that it takes long time to dry out the membrane if the purge is not effective. In this study, the effect of purge with a pulsating flow before shut down is investigated by experiment to improve effectiveness of purging. Furthermore, a cold start-up at -10 and -15°C after purge was performed to observe voltage variation. According to the results, purge performance with a pulsating flow is higher than that with a constant flow and the purge performance becomes higher as the pulsation frequency of the pulse generator increases. Moreover, the time before shut down at -10 and -15°C was extended enormously which is up to 48% for the frequency of 12 Hz due to the increasing lateral mass transport between the purge gas and the membrane.
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