The Experts below are selected from a list of 126 Experts worldwide ranked by ideXlab platform
Olivier Lottin - One of the best experts on this subject based on the ideXlab platform.
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local potential evolutions during proton exchange membrane fuel cell operation with dead ended anode part ii aging mitigation strategies based on water management and nitrogen crossover
Journal of Power Sources, 2017Co-Authors: Sofyane Abbou, Olivier Lottin, Sophie Didierjean, Jérôme Dillet, Gaël MaranzanaAbstract:Abstract Proton exchange membrane (PEM) fuel cells operate with Dead-Ended anode in order to reduce system cost and complexity when compared with hydrogen re-circulation systems. In the first part of this work, we showed that localized fuel starvation events may occur, because of water and nitrogen accumulation in the anode side, which could be particularly damaging to the cell performance. To prevent these degradations, the anode compartment must be purged which may lead to an overall system efficiency decrease because of significant hydrogen waste. In the second part, we present several purge strategies in order to minimize both hydrogen waste and membrane-electrode assembly degradations during Dead-Ended anode operation. A linear segmented cell with reference electrodes was used to monitor simultaneously the current density distribution along the gas channel and the time evolution of local anode and cathode potentials. To asses MEA damages, Platinum ElectroChemical Surface Area (ECSA) and cell performance were periodically measured. The results showed that Dead-End Mode operation with an anode plate maintained at a temperature 5 °C hotter than the cathode plate limits water accumulation in the anode side, reducing significantly purge frequency (and thus hydrogen losses) as well as MEA damages. As nitrogen contribution to hydrogen starvation is predominant in this thermal configuration, we also tested a microleakage solution to discharge continuously most the nitrogen accumulating in the anode side while ensuring low hydrogen losses and minimum ECSA losses provided the right microleakage flow rate is chosen.
Tero Hottinen - One of the best experts on this subject based on the ideXlab platform.
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operation of a planar free breathing pemfc in a dead end Mode
Electrochemistry Communications, 2007Co-Authors: Olli Himanen, Tero Hottinen, Saara TuuralaAbstract:Operation of a planar free-breathing PEMFC with pressurized anode was studied by constant current and polarization curve measurements. The anode outlet was equipped with a purge valve, whose duty cycle was varied. The results indicate that the cell is able to operate with 0.1 and 0.25 barg hydrogen pressures, with both dry and humid hydrogen. There were no significant differences in cell performance at different purge valve duty cycles. When the purge valve was completely closed signs of flooding were observed. Anode side flooding was reduced at higher hydrogen overpressure due to increased hydraulic permeation of water through the membrane.
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water balance in a free breathing polymer electrolyte membrane fuel cell
Journal of Applied Electrochemistry, 2004Co-Authors: Tuomas Mennola, Matti Noponen, Tanja Kallio, Mikko Mikkola, Tero HottinenAbstract:Water balance in a free-breathing polymer electrolyte membrane fuel cell was studied, focusing on the effect of anode conditions. The methods used were current distribution measurement, water collection from the anode outlet, and the measurement of cell polarization and resistance. Current density levels were 100 and 200 mA cm−2, temperature levels were 40 and 60 °C, and hydrogen stoichiometry range was from 1.5 to 2.5. The direction of hydrogen flow was varied. The fraction of product water exiting through the anode outlet varied from 0 to 58%, and it was found to increase with increasing temperature and hydrogen flow rate. When the general direction of hydrogen flow was against the direction of air flow, the percentage of water removal through the anode was smaller and the current distributions were more even than in the cases where the direction was the same as that of the air flow. This probably resulted from a more favorable distribution of water over the active area. The results also indicate that the net water transport coefficient varies across the active area. In further measurements, operation with the anode side in Dead-End Mode was investigated. It was also found that water distribution was more favorable when the general direction of hydrogen flow was against the air flow.
Sofyane Abbou - One of the best experts on this subject based on the ideXlab platform.
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local potential evolutions during proton exchange membrane fuel cell operation with dead ended anode part ii aging mitigation strategies based on water management and nitrogen crossover
Journal of Power Sources, 2017Co-Authors: Sofyane Abbou, Olivier Lottin, Sophie Didierjean, Jérôme Dillet, Gaël MaranzanaAbstract:Abstract Proton exchange membrane (PEM) fuel cells operate with Dead-Ended anode in order to reduce system cost and complexity when compared with hydrogen re-circulation systems. In the first part of this work, we showed that localized fuel starvation events may occur, because of water and nitrogen accumulation in the anode side, which could be particularly damaging to the cell performance. To prevent these degradations, the anode compartment must be purged which may lead to an overall system efficiency decrease because of significant hydrogen waste. In the second part, we present several purge strategies in order to minimize both hydrogen waste and membrane-electrode assembly degradations during Dead-Ended anode operation. A linear segmented cell with reference electrodes was used to monitor simultaneously the current density distribution along the gas channel and the time evolution of local anode and cathode potentials. To asses MEA damages, Platinum ElectroChemical Surface Area (ECSA) and cell performance were periodically measured. The results showed that Dead-End Mode operation with an anode plate maintained at a temperature 5 °C hotter than the cathode plate limits water accumulation in the anode side, reducing significantly purge frequency (and thus hydrogen losses) as well as MEA damages. As nitrogen contribution to hydrogen starvation is predominant in this thermal configuration, we also tested a microleakage solution to discharge continuously most the nitrogen accumulating in the anode side while ensuring low hydrogen losses and minimum ECSA losses provided the right microleakage flow rate is chosen.
Jari Ihonen - One of the best experts on this subject based on the ideXlab platform.
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optimization study of purge cycle in proton exchange membrane fuel cell system
Journal of Power Sources, 2013Co-Authors: Kaj Nikiforow, Henri Karimaki, Tommi Keranen, Jari IhonenAbstract:Abstract In PEMFC ( proton exchange membrane fuel cell ) systems operating in Dead-End Mode, hydrogen purges are needed to remove accumulated inert gases and liquid water from the anode side of the fuel cell stack. Hydrogen purges were studied using different humidity levels, purge times, and purge triggering criteria. The purged gas volume and composition were accurately measured with fast data acquisition and an advanced experimental set-up. The experiments were done with constant current density with aim of keeping the anode gas recirculation rate constant. Fuel utilization per pass varied as the hydrogen content on the anode side changed. This study demonstrates how the optimized purge strategy changes with a changing humidity level. It also shows that high fuel efficiency (>99%) is easily reached and that with optimized purge strategy a very high fuel efficiency (99.9%) can be reached. It was also shown that concentration polarization due to accumulation of inert gases on the anode side is two times higher than values obtained by theoretical calculations. This result is significant for purge strategy and system design.
Min Soo Kim - One of the best experts on this subject based on the ideXlab platform.
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Experimental study on enhancing the fuel efficiency of an anodic Dead-End Mode polymer electrolyte membrane fuel cell by oscillating the hydrogen
International Journal of Hydrogen Energy, 2010Co-Authors: Jong Won Choi, Yong-sheen Hwang, Suk Won Cha, Min Soo KimAbstract:Abstract This paper investigates how to improve the fuel efficiency of an anodic Dead-End Mode fuel cell for portable power generation. Generally, a periodic purge process in anodic Dead-End operation is required to avoid anode flooding caused by back diffusive water from the cathode. However, during the purge process, small amounts of the hydrogen are discharged with the water, lowering the fuel utilization efficiency. Therefore, hydrogen pulsations are introduced and experimental attempt to minimize the purge frequency is conducted in this study. The experimental results indicate that pulsation reduces partial pressure of the water vapor in the anode channel, increasing the interval between purges by approximately three times, thus improving overall efficiency.