Air Purification and Filter Design for Mobile APU Based on PEM Fuel Cell

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F60461373%3A22310%2F18%3A43916108" target="_blank" >RIV/60461373:22310/18:43916108 - isvavai.cz</a>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Air Purification and Filter Design for Mobile APU Based on PEM Fuel Cell

Original language description

Modern rescue and military units require for their efficient work numerous electronic devices. Number of devices used rapidly grows. For such services long-lasting and reliable energy supply for outdoor activities, represents an important issue. Typical long-time communication and necessary equipment in outdoor operations comprises 100-200 W of base load and up-to 300 W of peak consumption. Auxiliary power units (APU) are often used for longtime operation. PEM fuel cells represent proven technology for efficient conversion of chemical energy of fuel into electrical energy. They have several important advantages as high efficiency, flexibility, process intensity, nontoxic reaction products and silent operation. This fact allows application of fuel cells also in areas sensitive to exhalations, e.g. mobile medical beds or closed rooms. PEM fuel cell based mobile APU thus represents promising solution to ensure required power. Its main advantages are high flexibility and efficiency, high process intensity, instantaneous refueling and absence of moving parts. APU weight should not exceed 15 kg limit. It represent upper weight limit of the entire system, excluding pressurized gas cylinders. Logical solution is to use ambient air as an oxidant in order to reduce complexity of the system. Present work deals with development of PEM fuel cell base APU unit. Typical electric consumption of connected devices is not constant in time and varies significantly. It is in contradiction to the preferred PEM fuel cell operation regime. Also as peroxide radicals are generated during PEM fuel cell operation on electrodes, these radicals can attack membrane and catalyst support. Used solution to reduce this phenomenon is periodic short circuiting of fuel cell for couple of milliseconds. Mentioned specific operation needs of PEM fuel cell must be accomplished by suitable energy management and combination with correspondingly sized accumulators. Li-ion accumulators represent suitable option to solve this task. It is due to their low weight and high charging/discharging currents. Another option is the use of supercapacitor instead accumulator. The main task for power management of APU is to minimize variation in output voltage with respect to the PEFC operation and also with varying load of connected devices. All components have to be able to operate with high flexibility in the broad range of temperatures, including low ones. Selection of components was limited due to the set requirement on the weight of the system. The best ration between desired stability and weight were determined for system consist of PEM fuel cell, supercapacitor with small capacitance and accumulator able to work with high currents. Another issue of PEMFC based APU is requirement for air purification. Especially in the case of operation in polluted air e.g. near to the fire. Impurities presented in the air can reduce fuel cell lifetime. Solid impurities like dust can deposit on cathode surface and in combination with produced water form a sludge blocking distribution channels and gas distribution layers of the fuel cell. Also platinum nanoparticles used as a catalyst can be poisoned by the various pollutants often presented in the air in industrial agglomerations. Most dangerous is dihydrogen sulfide and other sulfur compounds, which are known as strong poisons for platinum catalysts. Carbon monoxide is dangerous only on the anodic (hydrogen) side, because on the cathodic side can be oxidized by incoming air. Nitrous oxides can oxidize of catalysts support typically based on carbon black. Last group of potentially dangerous air pollutants are organic compounds like benzene, toluene and other. These compounds if adsorbed can block the catalyst surface. Filters for removal of mechanical particles with diameter down to 0.2 µm are commercially available today. The active carbon can absorb chemical impurities. Promising approach to air treatment represents use of filters with interlayer of active carbon. Another important parameter for application in APU is power demand of blowers and thus pressure drop over the filter. Commercial filters was tested with respect to absorption capacity and pressure drop. On the base of these data filter suitable for operating fuel cell was selected. However, no one filter exhibits sufficient absorption capacity. Improving is possible by different ways as adding extra layer of active carbon to increase their capacity for individual pollutants removal, combination of filter with special sorbents in form of pellets or spherical, adding extra honeycomb filter with high specific selectivity. By this way it was possible to produce filters optimized for different environment, e.g. for industrial areas, highways, plantation, mines, sandpits and others. As a final wok the assembly of all required APU components to the limited space of standard suitcase was done. Also the design of air input and output, controlling buttons and power connectors were done.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

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

Project

<a href="/en/project/VI20152019018" target="_blank" >VI20152019018: Development and realization of autonomous DC power supply with hydrogen fuel cell</a><br>

Continuities

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

Publication year

2018

Confidentiality

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