Steady-State And Dynamic Analysis Of Solid Oxide Fuel Cell

Solid oxide fuel cells(SOFCs)with the characteristics of high operating temperature,a wide of kinds of fuels and excellent generating efficiency,gain the popularity among the researcher among the world in recent years.The temperature uniformity and component concentration distributions in solid oxide fuel cells during operating processes can influence the cell electrochemical and thermal characteristics.As the result,in my task A three-dimensional thermal-fluid numerical model including electrochemical reactions and water-gas-shift(WGS)reaction for a single channel solid oxide fuel cell is developed to study the steady-state and dynamic-state characteristics.A single cell experimental system of solid oxide fuel cell has been established to study the electrical performance of the solid oxide fuel cell using the pure hydrogen as fuel gas in my task.The experimental results show that the experimental system is stable because the decrement of electric performance is under 10%in the 100h stable test and the polarization curve is excellent.On this basis we establish a single cell numerical model using pure hydrogen,and the numerical model result is compared with the experimental result,which testifies the accuracy and reliability of the numerical model.Based on the SOFC numerical model fueled with pure hydrogen,the SOFC numerical model fueled with carbon monoxide and hydrogen is established.The distribution of gases concentration,temperature,fuel efficiency and thermal stress in the solid oxide fuel cell under typical working conditions can be obtained by numerical calculation.These parameters are difficult to be obtained by experimental means.In addition,the influence of co-flow and counter-flow on the steady-state characteristics of solid oxide fuel cells is also studied,which shows that the flow direction doesn,t influence the electric performance obviously while influences the distribution of temperature and temperature gradient obviously.Finally,the influence of operating temperature and operating pressure on the steady-state characteristics of the solid oxide fuel cell is studied.The results show that the higher the operating temperature and operating pressure is,the better the electrical performance of the solid oxide fuel cell is.At last,based on the SOFC steady state model,the SOFC transient model is established to calculate the dynamic response of parameters when the voltage change and the anode inlet velocity change and the influence of changing load speed on the dynamic character.The results show that the dynamic response speed of electrical signal is faster than that of other parameters.In addition,there is the overshoot phenomenon and undershoot phenomenon in many dynamic response processes and the changing load speed influences the dynamic response time and the overshoot and undershoot amplitude of the solid oxide fuel cell.