• Applied Chemistry for Engineering
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• v.33 no.6
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• pp.646-652
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• 2022

The dead-end anode (DEA) system is a method that closes the anode outlet and supplies fuel by pressure. The DEA method could improve fuel usage and power efficiency through system simplification. However, flooding occurs due to water and nitrogen back diffusion from the cathode to the anode during the DEA operation. Flooding is a cause of decreased fuel cell performance and electrode degradation. Therefore, tthe structure and components of polymer electrolyte membrane fuel cell (PEMFC) should be optimized to prevent anode flooding during DEA operation. In this study, the effect of a porous flow field with metal foam on fuel cell performance and fuel efficiency improvement was investigated in the DEA system. As a result, fuel cell performance and purge interval were improved by effective water management with a porous flow field at the cathode, and it was confirmed that cathode flow field structure affects water back-diffusion. On the other hand, the effect of the porous flow field at the anode on fuel cell performance was insignificant. Purge interval was affected by metal foam properties and shown stable performance with large cell size metal foam in the DEA system.

• Applied Chemistry for Engineering
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• v.28 no.1
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• pp.118-124
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• 2017

An air cooling, open cathode type polymer electrolyte membrane fuel cell (PEMFC) has the advantages of system simplification and cost effectiveness. Open cathode PEMFC could suffer from reduced performance due to the membrane dehydration in low humidity of air. Effects of the cathode air flow rate, anode purge interval and long term storage on PEMFC performance were investigated in this work. Fan voltage is an important factor on air cooling PEMFC performance because the cathode air flow rate and stack temperature were controlled by fan voltage. The dead ended anode (DEA) method was applied to increase hydrogen usage. Periodical purge was used to discharge accumulated water and gas. The influence of long term non-operating condition on PEMFC performance degradation due to the membrane dehydration was also studied and the quick recovery method was developed.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.687-693
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• 2019

As the hydrogen fuel cell market is expanded starting from hydrogen electric vehicle and power generation field, the demand for fuel cells and hydrogen increases recently. Therefore, research works on fuel cell durability and fuel efficiency are required in order to activate the fuel cell market and commercialization. A dead-ended anode system was used in this study to optimize the fuel cell performance and fuel efficiency. The effect of purge condition according to the applied current and hydrogen supply pressure on the fuel cell performance were evaluated. In addition, the influence of water back diffusion on the different electrolyte membrane thickness was analyzed. The accumulated water was purged with a solenoid valve in the case of 3% voltage decrease in the dead-ended anode system. The experiment was performed with the hydrogen supply pressure of 0.1~0.5 bar and purge duration of 0.1~1 second. A maximum fuel efficiency of 98.9% was achieved under the purge duration of 0.1 s and hydrogen supply pressure of 0.1 bar with a NR 211 (25.4 um) membrane. However, the fuel cell performance decreased in a long-term operation due to some frequent flooding. The fuel efficiency and purge interval increased due to decreased back diffusion rates of the water and nitrogen with a NR 212 (50.8 um) membrane.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.531-538
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• 2019

As the performance of PEMFC has been improved, the water and heat generated by reaction have increased so, the water and heat management of PEMFC is becoming more important. In this study, hydrogen recirculation was applied as the water management technique and the effect of recirculation flow rate, purge interval and duration on the performance of PEMFC was investigated. Anode pressure, fuel humidity and utilization, water discharge amount was measured to check the effect of purge conditions on performance. As the recirculation flow rate has increased, the performance of PEMFC became lower due to decrease of anode outlet pressure. According to the purge conditions, instantaneous voltage drop has occurred because of accumulated water. In frequent purge conditions, the performance of PEMFC gradually decreased due to fuel humidity control failure. Stable performance and high fuel utilization was achieved on this work by analyzing the effect of purge conditions.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.2
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• pp.136-147
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• 2015

Dead-ended operation of Proton Exchange Membrane Fuel Cell(PEMFC) provides the simplification of fuel cell systems to reduce fuel consumption and weight of fuel cell. However, the water accumulation within the channel prohibits a uniform supply of fuel. Optimization of the purge strategy is required to increase the fuel cell efficiency since fuel and water are removed during the purge process. In this study, we investigated the average voltage output which depends on two interrelated conditions, namely, the supply gas pressure, purging valve open time. In addition, flow visualization was performed to better understand the water build-up on the anode side and cathode side of PEMFC in terms of a variety of the current density. We analyzed the correlation between the purge condition and water flooding.