Study On Properties Of Micro-Scale Flow And Heat Transfer Within The Porous Electrode Of SOFC

Under the dual constraints of the limited natural resources and strict requirements of environmental protection, it is a great challenge to achieve the sustainable development of both economy and society. The energy problem is especially prominent under this condition. Solid Oxide Fuel Cell (SOFC) system is the most attractive novel energy solution in the long term. It is of great importance to change the existing energy structure, promote China's sustainable development and enhance national energy security. SOFC development satisfies the security, diversification and consistency demand of energy supply. The anode support SOFC is so superior that it is the major research and development direction of new generation of SOFC. The anode support SOFC is highly related to two key issues: the micro-scale flow simulation within the porous electrode and the measurement of effective thermal conductivity of porous electrode. This paper conducts an intensive research of the above focuses.In the first instance, the micro-scale study of convection-diffusion process of multi-component gases within the porous anode of anode support SOFC is carries out. Firstly, a rational simplified physical model is proposed based on certain assumptions. Secondly, the lattice-Boltzmann model for the multi-component gas flow is established with a clear physical basis. Thirdly, the scientific selection method of simulation parameters is proposed. And finally combined with the numerical construction technique of porous media, a lattice-Boltzmann parallel program is developed to analyze the micro-scale flow in porous anode. The calculation parameters are verified according to theoretical analysis, and the model verified based on experimental data. The effect of porosity, current density, fuel component and microstructure on mass transport and concentration polarization is analyzed. Conclusions are drawn out: Lattice-Boltzmann method is competent for the simulation of micro-scale flow in porous electrode, the concentration polarization of SOFC anode is highly related to fuel component, current density and anode microstructure. And according to this conclusion, the modified strategy of the microstructure of porous electrode is further proposed. The study conclusions are of great theoretical and practical engineering significance for the preparation of electrode with excellent performance and high power density output.Subsequently, the effective thermal conductivity measurement experiment for SOFC porous electrode is designed. Based on the real SOFC anode materials, advanced temperature signal acquisition and analysis techniques as well as the precise experimental conditions parameters controlling instruments, the effective thermal conductivity of porous electrode is measured accurately. The effect of porosity, gas flow, temperature, and microstructure on the thermal conductivity of porous media is analyzed. A reasonable combination model for the effective thermal conductivity is established and the combination factor is fitted by experimental data. The effective thermal conductivity fitting formula which is in accord with the operating characteristics of SOFC porous electrode is obtained. The study fills the blank of research on the real effective thermal conductivity of SOFC porous electrode. The conclusions laid a solid experimental foundation for the further research on thermal management of SOFC.