分配区点状结构对大面积燃料电池电流密度分布均一性、温度分布的影响

Current density and temperature distribution measurement and homogeneity analysis for a large-area proton exchange membrane fuel cell

Tianwei Miao

Chasen Tongsh

Jianan Wang

Peng Cheng

Jinqiao Liang

Zixuan Wang

Wenmiao Chen

Chao Zhang

Fuqiang Xi

Qing Du

Bowen Wang
Fuqiang Bai

Kui Jiao

a b s t r a c t
Homogeneous distribution of electro-chemical reaction rates among the activation surface is critical for improving the performance and durability of automotive proton exchange membrane fuel cells (PEMFCs). Segmented measurement technology is commonly used to characterize the local physical parameter distribution in the PEMFC. In this study, the local current density (LCD) and temperature distributions of a PEMFC with the activation area of 108 cm2 and various cathode flow fields are experimentally investigated. A homogeneity parameter is introduced to evaluate the homogeneity of LCD distribution. The results show that the performance and LCD distribution uniformity of the cell with dot-parallel flow field are much better than that with parallel and parallel-serpentine flow fields. The temperature distribution is generally positively correlated with LCD distribution. For the LCD distribution, the high LCD region firstly appears in the cathode downstream region, and gradually transfers upstream with increasing the current load. With the increase of inlet humidity, the LCD near the cathode inlet is improved due to the improvement of membrane hydration. Increasing the cathode stoichiometry can effectively improve the uniformity of LCD distribution, and mitigate the local oxygen starvation, especially at high loads.

Fig. 1. (a) Designed PCB for the segmented measurement (b) Numbers of the segmented regions (c) Arrangement of thermocouples (d) Error of initial temperature distribution.

Fig. 2. Flow field structures: (a) anode parallel flow field, (b) cathode parallel serpentine flow field, (c) cathode parallel flow field, (d) cathode dot-parallel flow field.

Table 1Fuel cell parameters.

这个装配力好小。装配力就算只是活性区的，名义压强只有0.32MPa

Fig. 3. Schematic diagram of the experimental setup.

Table 2 Cathode pressure difference between cathode inlet and outlet.

Fig. 4. Polarization and power density curves of the PEMFC with different cathode flow fields (a) RH 40%; (b) RH 60%; (c) RH 80%; (d) RH 100%.

Fig. 5. EIS curves of the PEMFC with the cathode dot-parallel flow field under different RH (a) 0.2 A cm2; (b) 1.0 A cm2; (c) 1.2 A cm2.

Zreal只有1毫欧cm2？常规双极板面电阻都不止这个数值，以后有机会留意一下其它文章的Zreal。

the LCD and temperature distributions of the cell with different cathode flow fields are discussed. The operating current density, RH and cathode stoichiometry are set as 0.8 A cm2, 60%, 2.5, respectively

Fig. 6. Effect of different cathode flow fields on the LCD distribution (a) parallel-serpentine flow field (b) parallel flow field (c) dot-parallel flow field.

在图6中没有进行网格划分的指示线，看起来有些不方便。

Fig. 7. Effect of different cathode flow fields on the homogeneity of LCDs.

不清楚为什么这个图没有标记横坐标，可能是和图9相对应的四个电流密度。

 (a) 0.2 A cm2 (b) 0.6 A cm2 (c) 1.0 A cm2 (d) 1.4 A cm2.

纵轴是经过放大的。

Fig. 8. Effect of different cathode flow fields on the temperature distribution (a) parallel-serpentine flow field (b) parallel flow field (c) dot-parallel flow field.

Fig. 9. Effect of current loads on LCD distribution (a) 0.2 A cm2 (b) 0.6 A cm2 (c)1.0 A cm2 (d) 1.4 A cm2.

和图6c是一个系列的数据，图9中绿色部分是名义电流值。可以看出区域的变化。

Fig. 10. Effect of current loads on temperature distribution (a) 0.2 A cm2 (b)0.6 A cm2 (c) 1.0 A cm2 (d) 1.4 A cm2.

Fig. 11. LCD distribution at RH 40% (a) 0.2 A cm2 (b) 0.6 A cm2 (c) 1.0 A cm2 (d)1.4 A cm2.

Fig. 12. LCD distribution at RH 100% (a) 0.2 A cm2 (b) 0.6 A cm2 (c) 1.0 A cm2 (d)1.4 A cm2.

Fig. 13. Effect of cathode stoichiometry on LCD distribution at 0.2 A cm2, and the cathode stoichiometry is (a) 2.5, (b) 3.0, and (c) 3.5.

Fig. 14. Effect of cathode stoichiometry on LCD distribution at 1.2 A cm2, and the cathode stoichiometry is (a) 2.5, (b) 3.0, and (c) 3.5.

Fig. 15. Effect of different cathode stoichiometry on the homogeneity of LCDs.

没有考虑温度不同和压力不同时候的电流密度分布。

图2空气入口截面不同，冷却液的排布状态不知道是否相同。

没有配合的膜电极图，如果膜电极在整个测量范围内均有催化层，A1和C9可能影响比较大。

分区电池的区块大小为20mm*20mm。

该小组仿真能力很强，如果有配合最优版型的流体分布状态的数值仿真分析，能让这个文章更加完整，甚至于计算出各个区域的电流密度分布值，和测量值进行比较。

Conclusion

In this study, we design a PCB (printed circuit board) method to
achieve the segmented measurement of the large-area PEMFC with
the activation area of 108 cm2. Effects of different cathode flow
fields, current loads, RH (relative humidity) and cathode stoichiometry on the LCD (local current density) and temperature
distributions are experimentally investigated. Comprehensively
considering the polarization curves, pressure drop and uniformity
of LCD distribution, the dot-parallel flow field shows the best performance among the three tested cathode flow fields. Therefore, it
can be concluded that adding the dot gas distribution area in the
inlet and outlet regions is an optimized design. The temperature
distribution is strongly related to LCD distribution because the
coupling effect of temperature and electrochemical reaction rates.
Optimal designs of coolant channels are given to improve the
uniformity of temperature distribution. In our experiments, the
high LCD regions generally appear at the cathode downstream area
when the load is relatively low (<0.6 A cm2). With the load
increasing, the produced water will hydrate the membrane in the
upstream region. At this time oxygen concentration will play a
significant role on the cell performance, and therefore the high LCD
regions gradually transfer upstream. Increasing the RH can effectively
improve the membrane hydration at the inlet area and
improve the cell performance. However, more water is produced
with increasing the load, and the high RH will aggravate the local
flooding in the downstream region. Therefore, adding a dry air
intake bypass is proposed to control the inlet RH and meet the
humidity requirements at different working conditions. Increasing
the cathode stoichiometry can effectively improve the uniformity
of LCD distribution, and mitigate the local oxygen starvation,
especially at high loads.