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Siegel C.,Siegel Schleimer Ingenieurs conseils S.a R.l. | Buder I.,Rhine-Waal University of Applied Sciences | Heinzel A.,Zentrum fur BrennstoffzellenTechnik ZBT GmbH
Electrochimica Acta | Year: 2013

This work reports sectional electrochemical impedance (EIS) measurements of a high temperature polymer electrolyte membrane (HTPEM) fuel cell. These measurements were taken using a high temperature stable polybenzimidazole membrane electrode assembly (MEA) doped with phosphoric acid (PBI/H 3PO4). Three different types of flow-fields (namely, a six channel parallel serpentine flow-field, a parallel straight flow-field, and a mixed-type flow-field) were analyzed in gas counter-flow and co-flow configuration under selected operating conditions. The current density distribution was also measured, and the results were presented to highlight the dominant factors that lead to inhomogeneous distributions. The results showed that the distribution mainly depended on the availability of oxygen, overlapped by the fluid-flow distribution. The situation changed once a carbon monoxide (CO) enriched gas was used at the anode side. In this case, the current density distribution decreased close to the cathode inlet and increased near the anode inlet. At high CO concentrations, the highest current densities were found close to the anode inlet. Sectional EIS measurements supported these observed trends and confirmed that the segments close to the anode inlet had a lower charge transfer resistance with a higher charge transfer resistance at segments closer to the anode outlet. © 2013 Elsevier Ltd. All rights reserved.

Ublekov F.,Bulgarian Academy of Science | Penchev H.,Bulgarian Academy of Science | Georgiev V.,Bulgarian Academy of Science | Radev I.,Zentrum fur BrennstoffzellenTechnik ZBT GmbH | Sinigersky V.,Bulgarian Academy of Science
Materials Letters | Year: 2014

A series of p-PBI phosphoric acid doped membranes, containing high levels of protonated montmorilonite (MMT-H), have been prepared using an easy and efficient procedure. The incorporation of MMT-H results in drastic increase (over 100%) of proton conductivity and mechanical properties, compared to the Celtec®-P membrane (commercial product of BASF Fuel Cell GmbH). This phenomenon could be attributed to water and phosphoric acid trapping in the MMT-H channels. © 2014 Elsevier B.V.

Sinigersky V.,Bulgarian Academy of Science | Ublekov F.,Bulgarian Academy of Science | Penchev H.,Bulgarian Academy of Science | Radev I.,Zentrum fur BrennstoffzellenTechnik ZBT GmbH | Georgiev V.,Bulgarian Academy of Science
International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM | Year: 2015

Polymer electrolyte membrane fuel cells (PEM FCs) generate electricity from an electrochemical reaction in which oxygen (air) and a fuel (e.g. hydrogen, low alcohols etc.) combine to form water and heat. On the other hand in PEM electrolysers water is split into hydrogen and oxygen. In both cases the polymer electrolyte membrane (PEM) is a crucial component of the device. One of the best known materials for preparation of high temperature ion conductive membranes is poly[2,2′-(p-phenylene)-5,5′-bisbenzimidazole] usually denoted as para-PBI (p-PBI). Here we report the preparation of phosphoric acid (PA) and potassium hydroxide (KOH) doped p-PBI membranes, loaded with very high concentrations of a clay material - protonated montmorillonite (MMT-H) and discuss some of their properties. The doped PBI membranes, containing filler, show considerable increase of the ionic conductivity as well as improvement of mechanical properties, compared to the doped PBI membranes, containing no MMT-H. For the PBI/MMT-H membranes doped with PA, proton conductivities up to 435 mS.cm-1 have been measured. The anion conductivity of the same membranes, doped with KOH exceed 1000 mS.cm-1. According to the literature at present PBI membranes, doped with KOH, are showing conductivities in the range of 100 mS.cm-1 (i.e. about 10 times lower than our membrane). The improvement of the ion conductivity has to be attributed to the water dopant mixture trapped in the MMT channels. MMT obviously acts as an electrolyte “reservoir”, which keeps the water contents in the membrane higher than the one provided solely by the environmental humidity. © SGEM2015.

Reinders M.,Research Institute for Water and Waste Management FiW | Beckhaus P.,Zentrum fur BrennstoffzellenTechnik ZBT GmbH | Illing F.,IBR Ingenieurburo Redlich und Partner GmbH | Misz U.,Zentrum fur BrennstoffzellenTechnik ZBT GmbH | And 4 more authors.
International Journal of Hydrogen Energy | Year: 2015

Hydrogen can play an important role in a future renewable energy economy. One promising method for hydrogen production with the potential for integration into a local supply chain in the vicinity of wastewater treatment plants was investigated during the EuWaK project at Emschergenossenschaft's Bottrop wastewater treatment plant (WWTP). The raw material for hydrogen production is digester gas, a renewable energy source. The digester gas is processed into bio natural gas and hydrogen. The hydrogen is used in a combined heat and power plant with a hydrogen engine to produce electricity and heat to supply a nearby school. An attractive alternative to a hydrogen engine is a fuel cell. Fuel cells require hydrogen conforming to stricter quality standards than H2 engines; therefore trialling quality management methods with a model fuel cell is an important safeguard in order to protect downstream fuel cells if digester gas derived hydrogen is to be used. Copyright © 2015 Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Burgmann S.,Zentrum fur BrennstoffzellenTechnik ZBT GmbH | Van Der Schoot N.,Zentrum fur BrennstoffzellenTechnik ZBT GmbH | Asbach C.,Institute fur Energie und Umwelttechnik e.V. | Wartmann J.,Zentrum fur BrennstoffzellenTechnik ZBT GmbH | Lindken R.,Zentrum fur BrennstoffzellenTechnik ZBT GmbH
Houille Blanche | Year: 2011

The investigation of the gas flow in a working fuel cell by means of optical measurement techniques like micro Particle-Image Velocimetry (μPIV) requires the generation of suitable tracer particles. In this work the analysis of tracer particle characteristics is described which serves as a means to identify suitable particles for wall-bounded gas flows. Several materials and different types of particle generators were examined to check for obtainable particle size distributions and particle concentrations. A simple experiment was designed to investigate the capability of the generated particles to adequately follow the flow. An optically transparent micro-channel with a 90° elbow was manufactured and the μPIV measurement technique is applied. Firstly, the gas-flow seeded with tracer particles is investigated within this 90° elbow micro-channel. Secondly, to check whether the measured flow structure in this previous case matches with the real flow, the same flow conditions are investigated using water as working fluid with solid tracer particles taking into account Re-ynolds number similarity. Thirdly, CFD-calculations using the same reference parameters as in the experimental investiga-tions were performed to quantify the deviation of the particle traces from the real flow streamlines. The results show ethy-lene glycol to be a suitable tracer material since the obtained tracer particles are optically detectable without severe image post-processing and since this material can be easily transformed into an aerosol with suitable concentrations and particle size distributions. The application of the μPIV technique on such a gaseous particle laden flow provided promising results concerning the intended application of this technique to operating fuel cells. © Société Hydrotechnique de France, 2011.

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