Temperature distribution characteristics and improvement of indirect internal reforming planar solid oxide fuel cells

doi:10.11949/0438-1157.20250230

Abstract

Abstract:

The indirect internal reforming solid oxide fuel cell (IIR-SOFC) is equipped with a reforming porous medium layer adjacent to the cell, utilizing the heat generated by the cell to reform the fuel gas and provide hydrogen for the cell. However, the reforming reaction affects the temperature distribution within the cell, making it uneven, which in turn affects the cell's power generation performance and lifespan. In this paper, the numerical simulation method was used to obtain the effects of fuel and air flow directions, operating temperature, and reforming gas flow rate on the temperature distribution and power generation characteristics of planar indirect internal reforming SOFC. A gradient distribution of catalyst loading in the reforming channel was used to improve the temperature distribution. The results show that the maximum temperature difference in the cell is smaller when the gas in the anode and cathode channels flows in the same direction than when it flows in the opposite direction. As the operating temperature increases, the maximum temperature difference inside the cell gradually increases. As the flow rate of the reforming mixed gas at the inlet increases, the temperature gradient and power density first increase and then decrease. After changing the distribution of catalyst loading in the reforming channel, the temperature distribution in the battery tends to be uniform, the temperature gradient is significantly reduced, and the maximum temperature difference is reduced by about 60%.

Key words: indirect internal reforming, fuel cells, gradient load, thermodynamics, numerical simulation

摘要：

间接内重整固体氧化物燃料电池（IIR-SOFC）在紧邻电池片处增设重整多孔介质层，利用电池产生的热量对燃料气进行重整，为电池提供氢气。但受重整反应影响，电池内部温度分布不均匀，从而影响电池的发电性能和寿命。采用数值模拟方法得到板式间接内重整SOFC的燃料和空气的流动方向、运行温度、重整气流速对电池温度分布及发电特性的影响，并在重整流道内采用催化剂载量梯度分布方式改进温度分布。结果显示，阴、阳极流道内气体顺流情况下电池最大温差比逆流时小；随着工作温度的升高，电池内的最大温差逐渐增大；随着重整混合气入口流速的增加，温度梯度及功率密度先增大后减小。在改变重整流道内的催化剂载量分布后，电池内温度分布趋向均匀，温度梯度明显减小，最大温差减小约60%。

关键词: 间接内重整, 燃料电池, 梯度负载, 热力学, 数值模拟

CLC Number:

TM 911.4

Shixue WANG, Zaihui YU, Yu ZHU, Jiting JIAN. Temperature distribution characteristics and improvement of indirect internal reforming planar solid oxide fuel cells[J]. CIESC Journal, 2025, 76(10): 5322-5335.

王世学, 于在辉, 朱禹, 蹇季廷. 间接内重整板式固体氧化物燃料电池的温度分布特性及改进[J]. 化工学报, 2025, 76(10): 5322-5335.

Figures/Tables 20

Fig.1 Schematic diagram of the IIR-SOFC geometric structure

Fig.2 Schematic diagram of different flow configurations in IIR-SOFC

Table 1 Geometric model parameters

参数	数值
阴/阳极流道宽度(w₂)/mm	2
阴/阳极流道高度(h_cha,a/h_cha,c) /mm	1
流道长度(l) /mm	100
重整流道宽度(w₁) /mm	4
重整流道高度(h_ref) /mm	4
阳极厚度(h_a) /mm	0.15
电解质厚度(h_el) /mm	0.1
阴极厚度(h_c) /mm	0.1
阳极/电解质/阴极宽度(w₁) /mm	4
连接体宽度(w₁) /mm	4
连接体高度(h_con,a/h_con,c)/mm	2

Table 2 Model boundary condition intent

边界条件	数值
重整流道入口气体组分(x_fuel,in)(N₂∶CH₄∶H₂O∶H₂)	0.225∶0.25∶0.5∶0.025
重整流道入口气体流速(u_fuel,in) /(m/s)	u_x =0.05,u_y =u_z =0
阴极入口气体组分(x_air,in)(N₂∶O₂)	79∶21
阴极入口流速(u_air,in) /(m/s)	u_x =1.5,u_y =u_z =0
阳/阴极出口压力（p_out）/atm	1
重整气体与阴极气体入口温度(T)/K	1073

Fig.3 Flowchart of solution process

Fig.4 Model validation

Fig.5 Two-dimensional cloud diagram of calculation results and schematic diagram of position of one-dimensional line taken

Fig.6 Variations in temperature and temperature gradient within battery under different flow configurations （T=1073 K，ufuel=0.05 m/s, uair=1.5 m/s，VCell=0.7 V，p=1 atm）

Fig.7 Power density curves under different flow configurations

Fig.8 Variation of temperature and temperature gradient at different initial operating temperatures along Line c

Fig.9 Power density curves at different operating temperatures of SOFC

Fig.10 Evolution of temperature and temperature gradient in reforming channel under different flow rates along Line c

Fig.11 Power density curves at different inlet flow velocities of reformed gas

Fig.12 Different catalyst loading methods in reforming channel

Fig.13 Temperature distribution in SOFC under different loading methods of reforming channel (Cross-section a)

Table 3 Statistics of maximum temperature， minimum temperature， maximum temperature difference， and temperature gradient within IIR-SOFC under different loading methods of reforming channel

负载方式	最高温/K	最低温/K	最大温差/K	最大温度梯度/(K/cm)
均匀负载	1098.2	1073.15	25.0	12.16
两分区梯度负载	1091.1	1073.15	17.9	7.17
三分区梯度负载	1083.3	1073.15	10.1	5.12

Fig.14 Variations in temperature and temperature gradient along Line c under different loading methods of reforming channel

Fig.15 Power density curves under different loading methods of reforming channel

Fig.17 Power density curves of IIR-SOFC with three tiered load mode at different air flow velocities

Table 4 Statistics of maximum temperature， minimum temperature， maximum temperature difference and temperature gradient within battery under different air flow velocities in three tiered gradient loading configuration

空气流速/(m/s)	最高温/K	最低温/K	最大温差/K	最大温度梯度/(K/cm)
1.1	1094.5	1073.15	21.35	10.63
1.2	1091.6	1073.15	18.45	9.08
1.3	1089.1	1073.15	15.9	7.48
1.4	1086.3	1073.15	13.15	6.50
1.5	1083.3	1073.15	10.1	5.12

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