| A fuel cell is an energy device that can directly convert the chemical energy of fuel into electrical energy.It is green and environmentally friendly and has high power generation efficiency.Solid oxide fuel cell(SOFC)is one type of the fuel cells.With its high efficiency and wide range of fuel application,it has wide application prospects in areas such as regional power supply.Biosyngas resources in my country are extensive and renewable,and the utilization of biosyngas has become a hot topic nowadays.Solid oxide fuel cells directly use biomass gas to generate electricity.Combining biomass gas with solid oxide fuel cells is a new type of fuel cell power supply.The focus of research on SOFC with biosyngas is to improve stability,extend battery life and reduce costs,which are closely related to battery characteristics.Therefore,the research goal of this paper is to establish a numerical model of biomass gas solid oxide fuel cells,and to conduct a more in-depth study of the battery characteristics.The research object of this paper is a flat anode supported solid oxide fuel cell under the external reforming condition of biomass gas as fuel.Using the method of computational fluid dynamics(CFD),a three-dimensional multiphysics coupling model is established to obtain the interior of the battery.Temperature field,electrochemical field and fuel composition distribution.The influence of key parameters such as electrode porosity(structure),fuel flow forward and backward(flow mode),working pressure(environment)and other key parameters on battery performance was studied.Based on the steady-state model,a transient model is established,and the dynamic response of battery temperature and current density under load changes is analyzed and discussed.The results show that when the SOFC with biosyngas studied in this paper works at1073K,under standard atmospheric pressure and the fuel is in the counter-current state,the maximum temperature difference inside the battery is 28K,and the peak power density is 3150W/m~2.When the porosity increased from 0.2 to 0.6,the peak power density increased from 2900W/m~2 to 3250W/m~2;when the working pressure increased steadily from 0.1013MPa to 0.3039MPa,the peak power density increased from3150W/m~2to 4600W/m~2.The fuel flow direction has a little effect on the electrochemical performance,and has a significant effect on the temperature distribution inside the battery.In the counter-current mode,the temperature distribution of the fuel cell is more uniform,the temperature at both ends is low,the middle temperature is high,and the maximum temperature reaches 1101K.the simulation results of the biosyngas SOFC transient model show that under sudden load voltage conditions,the fuel gas will be temporarily depleted,causing the current density to increase rapidly.Different voltage change speeds(step abrupt change,5s gradual change,10s gradual change,20s gradual change),the dynamic response of current density is different.When the voltage change time is 20s gradual change,almost no rapid increase in current density is observed. |
