Thesis for degree: Licentiate of Engineering

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6 Future work Future work will involve a study of an SOFC at multiscale which will offer promising knowledge to understand in detail the effect of design. To approach a successful electricity producing device with improved durability and life time, the understanding of multiscale transport and reaction phenomena within the cell is crucial. The next step is to model the involvement of microscale thermal diffusion through LBM connected to a macroscale CFD model. In the extended model the Knudsen diffusion, which describes collisions between the gas molecules and the porous structure (inside the porous electrodes), is also taken into account. Also the electrochemical reactions are prospected to contribute to capture valuable microstructural effects. These reactions occur at a limited part of the cell, the TPB, which can only be captured if modeled at microscale or smaller. Here the Monte Carlo method could offer advantages to improve the multiscale development. Another extension of the model is to include catalytic chemical surface reactions (instead of global kinetics expressions). These surface reactions can provide knowledge of the interaction between the transport processes and the reactions which will be valuable for fuel cell model development. The reforming reaction rate is dependent on temperature, concentrations, type and catalyst available. If the chemical reactions can be simulated on a microscale level, it would open up to involve all the detailed multistep chemical reactions. More knowledge and understanding of the effect behind the activation energy is important to enable reduction of the operating temperature. Physical and material properties are calculated from data found in literature and therefore experimental work is desired for validation of the model. 52
7 References [1] Andersson M., Yuan J., Sundén B., Review on Modeling Development for Multiscale Chemical Reactions coupled Transport Phenomena in Solid Oxide Fuel Cells, Applied Energy, 87, pp. 1461-1476, 2010 [2] Lehnert W., Meusinger J., Thom F., Modelling of Gas Transport Phenomena in SOFC Anodes, J. Power Sources, 87, pp. 57-63, 2000 [3] Sukop M.C., Thorne D.J. Jr., Lattice Boltzmann Modeling – An Introduction for Geoscientists and Engineers, Springer, NY, U.S., 2007 [4] Sanchez D., Chacartegui R., Munoz A., Sanchez T., On the Effect of Methane Internal Reforming in Solid Oxide Fuel Cells, Int. J. Hydrogen Energy, 33, pp. 1834- 1844, 2008 [5] Janardhanan V., Deutschmann O., CFD Analysis of a Solid Oxide Fuel Cell with Internal Reforming, J. Power Sources, 162, pp. 1192-1202, 2006 [6] Hecht E., Gupta G., Zhu H., Dean A., Kee R., Maier L., Deutschmann O., Methane Reforming Kinetics within a Ni-YSZ SOFC Anode Support, Applied Catalysis A: General, 295, pp. 40-51, 2005 [7] Yang Y., Du X., Yang L., Huang Y., Xian H., Investigation of Methane Steam Reforming in Planar Porous Support of Solid Oxide Fuel Cell, Applied Thermal Engineering, 29, pp. 1106-1113, 2009 [8] Yuan J., Huang Y., Sundén B., Wang W.G., Analysis of Parameter Effects on Chemical Coupled Transport Phenomena in SOFC Anodes, Heat Mass Transfer, 45, pp. 471-484, 2009 [9] Yuan J., Sundén B., Analysis of Chemically Reacting Transport Phenomena in an Anode Duct of Intermediate Temperature SOFCs, ASME J. Fuel Cell Sci. Tech., 3, pp. 687-701, 2006 [10] Nam J. H., Jeon D. H., A Comprehensive Micro-scale Model for Transport and Reaction in Intermediate Temperature Solid Oxide Fuel Cells, Electrochim. Acta, 51 pp. 3446-3460, 2006 53
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SOFC modeling from micro to macrosc
Page 3 and 4:
Abstract The purpose of this work i
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katalytisk omvandling av naturgas o
Page 7 and 8:
List of publications Journal public
Page 9 and 10:
3.2 Governing equations for the mac
Page 11 and 12:
Q source term (heat), W/m3 q heat f
Page 13 and 14: 1 Introduction After some time of d
Page 15 and 16: 2 SOFC modeling at smaller scales T
Page 17 and 18: etween 0.3 and 1.5 mm. In this conf
Page 19 and 20: Volume Method (FVM) which adopt the
Page 21 and 22: 2.3 Lattice Boltzmann method LBM ha
Page 23 and 24: streaming [3]. The concentration ρ
Page 25 and 26: ease the correspondence between the
Page 27 and 28: applicable for a mixture of two spe
Page 29 and 30: Figure 2.6: Effective boundary arra
Page 31 and 32: Table 2.1: Comparison of previous w
Page 33 and 34: Figure 2.7: Schematic illustration
Page 35 and 36: model is presented after the data c
Page 37 and 38: 3.2.1 Mass transport In the electro
Page 39 and 40: where h v is the volume heat transf
Page 41 and 42: Achenbach [43], it was found that t
Page 43 and 44: cathode are assumed to be similar t
Page 45 and 46: (3.48) where, besides the parameter
Page 47 and 48: for an isothermal spherical particl
Page 49 and 50: Velocity carried out to check wheth
Page 51 and 52: Figure 4.4: Velocity field [lu/ts]
Page 53 and 54: Table 4.2: Parameters in the SOFC a
Page 55 and 56: eactions are safely fulfilled. This
Page 57 and 58: Figure 4.8: Mole fraction distribut
Page 59 and 60: Table 4.5: Inlet mole fractions for
Page 61 and 62: Figure 4.12: Mole fraction distribu
Page 63: 5 Conclusions The physics and the t
Page 67 and 68: [25] Latt J., Hydrodynamic Limit of
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Thesis for degree: Licentiate of Engineering

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