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Development of Multi-scale Models for Transport Processes Involving Catalytic Reactions in SOFCs

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Author

Summary, in English

Several physical phenomena appear in anode-supported solid oxide fuel cells (SOFCs), such as multi-component gas species/charge flow, thermal energy and mass transfer. Meanwhile, generation and consumption of gas- and surface-phase species together with electric current production are involved at the active sites in different length scales. Therefore, various reactions in SOFCs are strongly coupled with the transport processes making the physical phenomena more complicated. An effective anode is the one that correctly balances each of the transport processes and the reactions. To deeply understand the chemical-reacting transport processes in the porous anode, a fully three-dimensional numerical calculation method (CFD approach) is further developed. The considered domain includes the porous anode, fuel gas flow channel and the solid interconnects. By calculating surface-phase species, the gas-phase species/heat generation and consumption related to the internal reforming reactions and the electrochemical reactions have been employed. The variable thermal-physical properties and transport parameters of the fuel gas mixture have also been taken into account. Furthermore, the heat transfer due to the fuel gas diffusion is implemented into the energy balance based on multi-component diffusion models. A multi-step heterogeneous steam reaction scheme based on the micro and detailed reaction mechanisms of Ni catalyst is employed in this study. The surface reactions include 42 irreversible elementary ones, and they account for the steam reforming, the water-gas shift reforming and Boudouard reactions. This microscopic reaction model describes the adsorption and desorption reactions of 6 gas-phase species (H2, CO, CH4, CO2, H2O and O2) and surface reactions of 12 surface-adsorbed species (Nis, Hs, Os, OHs, HCOs, CHs, CH2s, CH3s, CH4s, COs, CO2s, H2Os). Simulation results are presented and discussed in terms of the gas-phase species and temperature distributions, the chemical reaction rates of the gas- and surface chemical species, the catalyst surface coverage and the effects on the transport processes.

Department/s

Publishing year

2010

Language

English

Pages

37-56

Publication/Series

International Journal of Micro-Nano Scale Transport

Volume

1

Issue

1

Document type

Journal article

Publisher

Multi-Science Publishing

Topic

  • Energy Engineering

Status

Published

ISBN/ISSN/Other

  • ISSN: 1759-3093
  • FP7:226238