Research On The 3D Momentum,Species,Heat,and Electrochemistry Coupling Model For The Large Scale Fuel Cell Stacks

Compared with traditional power generation technology,fuel cell technology is an energy conversion technology that directly converts chemical energy of fuel into electrical energy.It has theoretically higher energy conversion efficiency than traditional thermal power generation technology.Solid oxide fuel cell(SOFC)is considered as a potential combined heat and power technology in marine applications.Because the manufacturing process of the current SOFC stack is expensive and time-consuming,it is not convenient to directly evaluate various parameters in the stack through experimental approach.In addition,as the SOFC stack is operated under high temperature conditions,it is difficult to measure the details of the multi-physics distribution inside the tiny channels of the stack.With the rapid development of computer technology,many complex scientific and engineering problems that cannot be solved by theoretical analysis or experimental measurement can already be realized by computer simulation.Three-dimensional simulation is considered to be an efficient and fast method for obtaining the internal working details with the stack while different designs are applied.In order to efficiently and accurately predict the distribution characteristics of various physical quantities in the SOFC stack,this paper firstly builds a numerical platform that can be used to describe the fully coupled phenomenon of multi-physics in SOFC stacks through the mathematical equations that couples the electrochemical models,electrochemical reaction kinetic models and fluid dynamics models.At the same time,in response to the shortage of the commercial simulation software ANSYS Fluent in the SOFC cell module,VC ++ is used to implement the secondary development of the software,and developed a multi-physics fully coupled solution subroutine for Fluent and the supporting use process.Experimental verification results show that the numerical platform has good accuracy and stability.Basing on the built numerical platform,for various simplified phenomena in the field of large-scale SOFC stack simulation.An 18-cells stack model and three 20-cells stack models are established to compare the differences in momentum-heat-species-electrochemistry distribution characteristics within the stack under different degrees of simplified control equations and simplified model structure.By analyzing and comparing the flow,species and heat transfer distribution inside the stack,the factors affecting the accuracy of the large-scale numerical simulation calculation of the SOFC stack are summarized,which provides guidance for the next development of theSOFC stack prediction model.Basing on the above research results,we take a more complicated interdigital fuel flow SOFC stack as an example to establish a full-scale multi-physics fully coupled three-dimensional numerical analysis model.The three-dimensional large scale model includes all the complicated solid,space and porous medium component structure.The momentum,mass,species,energy,charge conservation equations and anodic/cathodic electrochemical half reactions are coupled and well addressed to the corresponding zones for accurately simulating.Then,the air/fuel flows,hydrogen/oxygen mole fractions,temperature,electric current and anodic/cathodic electrochemical reactions distributing details within the stack are successfully and accurately predicted.After comparative analysis,it is shown that the developed model and the research methods involved can be used for guidance before similar experimental research.