Analysis For Numerical Model Of Cone-shaped Solid Oxide Fuel Cells

Solid oxide fuel cell?SOFC?is a promising energy conversion device,which offers high energy conversion efficiency and flexible fuel selectivity,and got universal attention from many countries.Engineering simulation modeling is one of the important tools for the development of solid oxide fuel cell technology.Numerical models can be used to study the effects of different variable parameters on fuel cell performance,and can also be useful in predicting the effects of variable parameter changes.This is important for us to optimize the cell performance by using the influence information of the variation parameters.SOFC has many different structural designs.The cone-shaped SOFC is an improved tubular SOFC design,which has a lightweight and compact structure.It can be stacked in series according to the requirements,so it can output a balanced voltage and current.In order to study the details of the work of the cone-shaped tube SOFC,we did the following work:1.According to the experimental parameters,the coupling model of the cone-shaped SOFC multiphysics is established.Then we calculated the V-I curve and compared with the experimental results.Good agreements indicate the accuracy of the model,which can be used to accurately describe the working process and details of the cone-shaped SOFC under the composite electrode.2.The calculation of the numerical model specifically shows the material distribution and current density distribution characteristics of the electrodes during the operation of the single cone-shaped SOFC.The material reaction is concentrated in the effective working area in the electrodes.The H2 and H2O have opposite distribution characteristics in the anode,and the distribution of O₂ is concentrated in the effective working area of the cathode.The electronic current density is mainly concentrated in the small-area cathode region,and there is no electronic current in the excess anode region.The ionic current mainly exists in a narrow region between the electrode and the dense electrolyte interface.In addition,the portion of the anode that exceeds the cathode has an enhanced effect on current and mass transfer.3.The calculation of the numerical model specifically shows the material distribution and current density distribution characteristics of the electrodes during the operation of the multi-in-series cone-shaped SOFCs,and compared the results with the single cell.The cells are sleeved in series,the electrode areas are overlapped,so the effective reaction areas are reduced;the resistance of material transfer is increased,and the reaction rate is decreased;when the current is transferred between the cells,there is ohmic resistance.Therefore,at the same working temperature,with the number of stacked cells increasing,the reaction rate of H₂ and O₂ reduced,the current density decreased,and the average output power density per cell decreased.Due to the change of the current path,the electronic current of the multilayer structure is mainly concentrated in the effective working areas of the cathode,and the ionic current is mainly concentrated in the electrolyte layer and the vicinity of the interface between electrolyte and cathode.As the resistance to material transport increases,the ionic currents in the electrolyte and anode interface regions concentrate in a narrower region.4.Cathode material properties affect the output performance of the cell,and effective conductivity is an important manifestation of material properties.So we chose to study the effect of effective conductivity on the V-I curve.As the effective electronic conductivity and effective ionic conductivity of the cathode increase,the output performance of the cell increases.