Influence of cell inertization and nitrogen purity on lifetime of PEM fuel cell

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60461373%3A22310%2F18%3A43916142" target="_blank" >RIV/60461373:22310/18:43916142 - isvavai.cz</a>

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RIV/60461373:22310/18:43916143

Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Influence of cell inertization and nitrogen purity on lifetime of PEM fuel cell

Popis výsledku v původním jazyce

PEM fuel cells represents a promising device for efficient conversion of chemical energy carried by fuel into electrical energy. Efficiency of energy conversion depends on activity of catalysts and ohmic resist of all components as membranes, electrodes, bipolar plates and etc. Ohmic loses on membrane can be reduced by using of so thin membrane as is possible. Permeability of hydrogen through membrane increase with decrease of their thickness. Inertization at the end of active period represents an important part of operating PEM fuel cell stack. This part of the fuel cell operational cycle is important both from lifetime and safety point of view. Significance of this step increases with increasing permeability of such membrane for hydrogen. This, especially during off period, results in formation of aggressive species in the catalytic layers of the gas diffusion electrodes enhancing their chemical degradation. As the hydrogen is removed from fuel cell interior and at the same time diluted during inertization, delated dangers are avoided. The traditional media for fuel cell inertization is nitrogen. It can be stored in a high pressure cylinders integrated into the fuel cell system. Such solution, however, is demanding due to the more reasons. As main of them following ones may be mentioned. Installation of such cylinder increases complexity and weight of entire system. At the same time, total volume of gas in cylinder is sufficient just for a limited number of inertization cycles before replacement or refilling is required. It makes the process complicated also from logistic point of view. An alternative solution represents production of nitrogen of sufficient purity on-site, preferably from air by means of membrane separation modules. In combination with corresponding compressing unit it represents inexhaustible source of nitrogen. Unfortunately, the membrane module is not able to produce nitrogen at purity higher than 99.9 %. As it follows from composition of the air. Oxygen represents main impurity in the produced nitrogen stream. Information available in literature on the impact of traces of oxygen in an inertization gas on the fuel cell stack lifetime and performance is, however, not sufficient yet. Thus, in the present work the impact of the oxygen residuals in a inertization nitrogen stream on performance of commercially available MEAs was followed by means of selected nitrogen production membrane modules under varions operational conditions. The results obtained allow assessing viability of this approach for practical application in field of small scale portable APU on the base of hydrogen fueled PEM fuel cells. One of aims of this work is determination of maximal concentration of oxygen in nitrogen. Efficiency of membrane modules increase with decreasing air flow and increasing input pressure. Energy demands for compression of air increase with output pressure. Energy for compressing unit come from fuel cell and slush efficiency and make enhanced demands to balancing system of whole system.

Název v anglickém jazyce

Influence of cell inertization and nitrogen purity on lifetime of PEM fuel cell

Popis výsledku anglicky

PEM fuel cells represents a promising device for efficient conversion of chemical energy carried by fuel into electrical energy. Efficiency of energy conversion depends on activity of catalysts and ohmic resist of all components as membranes, electrodes, bipolar plates and etc. Ohmic loses on membrane can be reduced by using of so thin membrane as is possible. Permeability of hydrogen through membrane increase with decrease of their thickness. Inertization at the end of active period represents an important part of operating PEM fuel cell stack. This part of the fuel cell operational cycle is important both from lifetime and safety point of view. Significance of this step increases with increasing permeability of such membrane for hydrogen. This, especially during off period, results in formation of aggressive species in the catalytic layers of the gas diffusion electrodes enhancing their chemical degradation. As the hydrogen is removed from fuel cell interior and at the same time diluted during inertization, delated dangers are avoided. The traditional media for fuel cell inertization is nitrogen. It can be stored in a high pressure cylinders integrated into the fuel cell system. Such solution, however, is demanding due to the more reasons. As main of them following ones may be mentioned. Installation of such cylinder increases complexity and weight of entire system. At the same time, total volume of gas in cylinder is sufficient just for a limited number of inertization cycles before replacement or refilling is required. It makes the process complicated also from logistic point of view. An alternative solution represents production of nitrogen of sufficient purity on-site, preferably from air by means of membrane separation modules. In combination with corresponding compressing unit it represents inexhaustible source of nitrogen. Unfortunately, the membrane module is not able to produce nitrogen at purity higher than 99.9 %. As it follows from composition of the air. Oxygen represents main impurity in the produced nitrogen stream. Information available in literature on the impact of traces of oxygen in an inertization gas on the fuel cell stack lifetime and performance is, however, not sufficient yet. Thus, in the present work the impact of the oxygen residuals in a inertization nitrogen stream on performance of commercially available MEAs was followed by means of selected nitrogen production membrane modules under varions operational conditions. The results obtained allow assessing viability of this approach for practical application in field of small scale portable APU on the base of hydrogen fueled PEM fuel cells. One of aims of this work is determination of maximal concentration of oxygen in nitrogen. Efficiency of membrane modules increase with decreasing air flow and increasing input pressure. Energy demands for compression of air increase with output pressure. Energy for compressing unit come from fuel cell and slush efficiency and make enhanced demands to balancing system of whole system.

Druh

O - Ostatní výsledky

CEP obor

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OECD FORD obor

10405 - Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis)

Projekt

<a href="/cs/project/VI20152019018" target="_blank" >VI20152019018: Vývoj a realizace nezávislého DC zdroje napájení s vodíkovým palivovým článkem</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2018

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů