| Solid oxide fuel cells(SOFC)can directly convert the chemical energy of the fuel into electrical energy,the conversion process is not limited to the Carnot cycle,and it has the advantages of high efficiency and environmental protection,great fuel flexibility,etc.,which is important to solve the problems of energy shortage and environmental pollution.As a configuration of SOFC,the MOLB-type SOFC has a promising prospect due to its corrugated anode-electrolyte-cathode(Positive-Electrolyte-Negative,PEN)design,which provides a large electrochemical reaction area and superior performance.A numerical model of MOLB-type SOFC was established with COMSOL software in this paper,and the solution is based on the finite element method,the influence law of structural parameters,operation conditions and material parameters on the performance of MOLB-type SOFC is systematically investigated.The main research contents of this paper are as follows.(1)The effects of rib width,electrode thickness,electrolyte thickness and flow channel height on the performance curves,composition distribution,temperature distribution and overpotential changes of MOLB-type SOFC were studied.The results show that the decrease of rib width can significantly reduce the concentration polarization and improve the output performance of cell.The maximum output power density of the cell is increased by 14.12%when the rib width is reduced from 1.9 mm to 1 mm.The thicker cathode electrode,the higher average temperature and temperature gradient of the cell,and the better output performance.The increase of anode thickness increases the gas diffusion resistance in anode,resulting in higher concentration polarization and lower gas distribution uniformity.The reduction of electrolyte thickness can significantly reduce the ohmic polarization and improve the performance and fuel utilization of cell.When keeping the width of the cell is a constant,the electron current density increases with the increase of the flow channel height.(2)The effects of the inlet fuel fraction,anode inlet flow rate and cathode inlet flow rate on the performance of MOLB-type SOFC were investigated.The results show that the higher inlet hydrogen molar fraction and anode inlet flow rate,the better output performance of the cell,while the lower the fuel utilization.The average temperature and temperature gradient of the cell increase with the increase of inlet hydrogen molar fraction.The concentration polarization is significant under low cathode inlet flow rate,while the concentration polarization and temperature of the cell decrease with the increase of the cathode inlet flow rate.When the cathode inlet flow rate reaches 3 m/s,the effect of further increasing the cathode inlet flow rate on the performance of MOLB-type SOFC is little.(3)Six models of multi-channel MOLB-type SOFC under different gas flow patterns were developed,the effect of the flow pattern on the performance of the cell was studied.The results show that the peak temperature of the cell is reduced by 38.9K by changing the gas flow pattern,the best performance is obtained when the fuel and air flow are in contrary direction,and at the same time the gas flow direction of the upper and lower layers of cell stack is also opposite.(4)The effects of thermal conductivity of the interconnector and contact resistance on the temperature distribution,polarization loss and electrical performance of MOLB-type SOFC were investigated.The results show that the thermal performance of SOFC can be improved by increasing the thermal conductivity of the connector,but causes an increase of activation polarization and ohmic polarization.The higher contact resistance,the lower temperature of the cell.The peak temperature decreases by 4.9 K when the contact resistance increases from 0.01Ω·cm~2 to 0.04Ω·cm~2.The average current density of the cell decreases approximately linearly with the increase of the contact resistance. |
PDF Full Text Request