Cross-scale modeling and optimization analysis of the solid oxide fuel cell cogeneration system based on the heat current method

Abstract

The multi-scale, multi-component, multi-process, and multi-parameter characteristics increase intermediate variables and complexity of modeling and analysis of solid oxide fuel cell cogeneration systems. This paper applied the standard thermal resistance for constructing the heat current model to analyze the overall heat transfer performance of the external heat exchangers. On this basis, the research introduced the equivalent electric circuit for presenting the internal electrochemical process and then proposed the overall cross-scale modeling of the solid oxide fuel cell cogeneration system from the internal heat and mass transfer and electrochemical processes to the various external heat exchangers. Moreover, considering the internal and external multi-processes, the system's overall constraints were derived. The simulation results show that the total energy utilization rate of the solid oxide fuel cell cogeneration system is 79.12 %. Besides, the influences of water-to-carbon ratio, excess air coefficient, thermal conductances of each heat exchanger, and ambient temperature on the system performance were developed. The optimal operation parameters are given for improving the maximum net power generation of the system. Finally, the proposed cross-scale modeling method is feasible and convenient for analyzing and improving the solid oxide fuel cell cogeneration system.