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1.
Thinh X. Ho Pawel Kosinski Alex C. Hoffmann Arild Vik 《International Journal of Hydrogen Energy》2009
This paper investigates a planar anode-supported solid oxide fuel cell (SOFC) with mixed-conducting electrodes. Direct internal methane reforming in the high-temperature cell is included. The numerical model used is three-dimensional, a single computational domain comprising the fuel and air channels and the electrodes–electrolyte assembly. The oxygen ion transport through the electrolyte is mimicked with an algorithm for Fickian diffusion built into the commercial computational package Star-CD. The equations describing transport, chemical and electrochemical processes for mass, momentum, species and energy are solved using Star-CD with in-house developed subroutines. Results for temperature, chemical species and current density distribution for co- and counter-flow configurations are shown and discussed. For co-flow, a sub-cooling effect manifests itself in the methane-rich region near the fuel entrance, while for counter-flow a super-heating effect manifests itself somewhat further downstream, where all the methane is consumed. Effects of varying air inlet conditions are also investigated. 相似文献
2.
The effect of heavy tar compounds on the performance of a Ni-YSZ anode supported solid oxide fuel cell was investigated. Both toluene and naphthalene were chosen as model compounds and tested separately with a simulated bio-syngas. Notably, the effect of naphthalene is almost negligible with pure H2 feed to the SOFC, whereas a severe degradation is observed when using a bio-syngas with an H2:CO = 1. The tar compound showed to have a remarkable effect on the inhibition of the WGS shift-reaction, possibly also on the CO direct electro-oxidation at the three-phase-boundary. An interaction through adsorption of naphthalene on nickel catalytic and electrocatalytic active sites is a plausible explanation for observed degradation and strong performance loss. Different sites seem to be involved for H2 and CO electro-oxidation and also with regard to catalytic water gas shift reaction. Finally, heavy tars (C ≥ 10) must be regarded as a poison more than a fuel for SOFC applications, contrarily to lighter compounds such benzene or toluene that can directly reformed within the anode electrode. The presence of naphthalene strongly increases the risk of anode re-oxidation in a syngas stream as CO conversion to H2 is inhibited and also CH4 conversion is blocked. 相似文献
3.
In order to improve the single-chamber performance of a traditional anode-supported single-chamber solid-oxide fuel cell with NiO–ScSZ anode and ScSZ electrolyte, the modification of the anode with a fine nickel catalyst by impregnation method was exploited. Catalytic test demonstrated the nickel catalyst had higher catalytic activity than the severe sintered nickel–cermet anode between 700 and 900 °C, especially at the lower temperature range. SEM examination demonstrated the nickel catalyst impregnation increased the roughness of the nickel grains within the anode. Furthermore, some surfaces of the ScSZ grains are also covered with very fine nickel catalyst. By operating on a methane-air mixture gas with methane to oxygen ratio of 1.3:1, the cell with its anode impregnated with the nickel catalyst showed an open circuit voltage and peak power density of 0.954 V and 119 mW cm−2 at a furnace temperature of 750 °C, respectively, as a comparison of 0.893 V and 79 mW cm−2 for the cell without the nickel catalyst. The improved cell performance was attributed to the higher cell temperature and increased anode catalytic activity for methane partial oxidation. 相似文献
4.
(La0.6Ba0.4)(Co0.2Fe0.8)O3 (LBCF) is synthesized by a sol–gel method as a Cr-tolerant cathode for intermediate-temperature solid oxide fuel cells (ITSOFCs). The electrochemical performance and Cr deposition process for the O2 reduction reaction on LBCF cathodes in the presence and absence of a Fe–Cr alloy interconnect are investigated in detail, in comparison with a (La,Sr)(Co,Fe)O3 (LSCF) electrode. Cr deposition occurs for the O2 reduction reaction on LBCF electrodes in the presence of Fe–Cr alloy. Very different from that observed for the reaction on the LSCF cathode, Cr deposition on the LBCF electrode/gadolinia-doped ceria (GDC) electrolyte system is very small and shows little poisoning effect for O2 reduction on LBCF electrode. The results demonstrate that the LBCF electrode has a high resistance towards Cr deposition and high tolerance towards Cr poisoning. 相似文献