Biomass Gas SOFC Multiphysics Matching Optimization Design And Thermal Management

Under the dual pressures of energy shortage and environmental pollution,China's coal-based energy consumption structure needs to be adjusted.Accelerating the development of renewable energy is an important measure to accelerate the transformation of energy consumption structure.As a large agricultural country,China has abundant biomass energy reserves.Biomass gasification technology is one of the ways to efficiently utilize biomass energy,while solid oxide fuel cell(SOFC)can directly use biomass gas as fuel and power generation efficiency is less affected by power generation scale,which is very suitable for small and widely distributed biomass gas.Biomass gas SOFC power generation system has a good development prospect and is one of the main development directions of biomass energy utilization in the future.This paper established a three-dimensional multi-field coupled numerical analysis model for SOFC single cells by using OpenFOAM,and carried out multi-physics matching optimization design and thermal management research for biomass gas SOFC.The main research work is as follows.The effects of the microstructure parameters and the operating parameters on cell performance were studied.The effects of flow configurations and arrangements of gas channels on cell performance were studied.Under the thermal safety constraints,the relationship between the minimum cooling air flow and the average current density of the SOFC was studied.The effects of cell structure parameters,gas inlet temperature and fuel utilization on this relationship were studied.The following conclusions were obtained:1)During the process of increasing the porosity from 0.3 to 0.6,the output voltage and power density first increase and then decrease,and the cell output performance is best when the porosity is 0.4-0.5.As the pore size is increased from 0.3?m to 1.2?m,both the output voltage and the power density increase.However,when the pore size is increased to 0.6?m,the output performance is improved little.2)Increasing the operating temperature,the cell output performance continues to increase.When the operating temperature is increased,the current density fluctuates more drastically and the temperature distribution is more uniform.As the gas flow rate increases,the output performance increases and the fuel utilization decreases.The maximum power density point is selected to obtain the matching relationship between the average current density and the fuel utilization rate under the optimal operating conditions.Increasing the operating pressure,the cell output performance is continuously improved,and the multi-physics distribution is more uniform.However,when the operating pressure is higher than 0.5Mpa,the performance of the cell is improved little.3)The three flow configurations of co-flow,counter-flow,and cross-flow have little effect on the output performance of the cell.The multi-physics distribution is the most uniform when co-flow configuration.The two arrangements have little effect on the output performance of the cell,and the multi-physics distribution is more uniform when staggered.4)An exponential function relationship between the average current density and the minimum cooling air flow rate is obtained under conditions that satisfy the maximum temperature and maximum temperature gradient limits.As the current density increases,the minimum required cooling air flow also increases.The gas inlet temperature has a significant effect on the optimum amount of cooling air.Under the condition of an average current density of 10000 A/m~2,when the inlet temperature is changed from 1073K to 873K,the optimal cooling air flow is increased by 2.5 times.