燃料电池端板设计和生产验证实践：由接触电阻判和传质阻抗确定端板变形量、厚度优化［设计因素其十二］

Design and manufacturing of end plates of a5 kW PEM fuel cell

S．Asghari

M．H．Shahsamandi

M．R．Ashraf Khorasani

Abstract

End plate is one of the main components ofthe proton exchange membrane （PEM） fuel cells． The major role of the end plateis providing uniform pressuredistribution between various components of the fuel cell （bipolar plates， etc．）and consequently reducing contact resistance between them． In this study aprocedure for design of end plate has been developed． At first a suitablematerial was selected using various criteria． Then a finite element （FE）analysis was accomplished to analyze endplate deflections and get its optimized thickness． After fabricating theend plates， a single cell was assembled and electrochemical impedancespectroscopy （EIS） tests were carried out to ensure their good operation． A 5kW fuel cell assembled with these end plates was tested at different operatingconditions． The test results show an appropriate assembly pressure distributioninside the stack which indicates good performance of the designed end plates．

这篇文章和燃料电池电堆活性区接触应力分布的影响因素：端板厚度、端板材料、密封模型、密封件硬度、电池节数、电池位置（设计因素其二）有关联。前者计算变形，后者计算应力。

端板变形多大是允许的？

这篇文章如果结合压敏纸的数据就更加完美了。

Fig． 1 End plate roles： a） providing  passages for reactant gases and coolant fluid， b） Providing uniform contact  pressure distribution in the stack．

Fig． 2 e Effect of clamping pressure on  the fuel cell performance．

Fig． 3 e Inserted Teflon parts into the end  plate to act as the inlet and outlet passages．

Fig． 4 e Components of the geometrical  model．

Fig． 5 e Load－deflection diagram of the  disc spring stack used in the PEM fuel cell stack．

Fig． 6 e Contour plot of end plate  deformation along direction 3．

Fig． 7 e Effect of end plate thickness on  the maximum principal stress in bipolar plate．

Fig． 8 e Effect of end plate thickness on  the maximum end plate displacement．

Fig． 9 e Effect of end plate thickness on  the maximum bipolar plate displacement．

Fig． 10 e Impedance plots of the single  cell assembled with different clamping torques but under the same operational  conditions： current density： 0．18 AcmL2； stoichiometry： 1．5／2．0 for H2／air；  RH： 90％； cell temperature： 70 C； back pressure： 5 psig．

Fig． 11 e Dependence of the high  frequency resistance （HFR） with the clamping torque under operating conditions：  current density： 0．18 A cmL2； stoichiometry： 1．5／2．0 for H2／air； RH： 90％；  cell temperature： 70 C； back pressure： 5 psig．

Fig． 13 e Polarization curves of  individual cells of the 5 kW stack； Powere current curve of the 5 kW stack．

Conclusion

In this study a FE model was developed to  investigate the effect of end plate  thickness on the deflection of bipolar plate and end plate after applying the  clamping pressure．

Considering the FE results， the optimum  thickness was chosen to be 35 mm． A single cell which assembled by these end  plates was tested by EIS test method at different torques．

It was determined that the ohmic resistance at 25 Nm is approximately  as equal as the value recommended by the MEA manufacturer． Regarding the  EIS test results， the end plates were used to assemble a 5 kW PEMFC stack．  Analyzing the results of the leakage  test and also voltage－current diagrams of this stack determined the good  performance of the end plates in producing adequate and uniform clamping pressure  in the individual cells of the stack and also obtaining the desired nominal  power．

关于密封测试方案与后续根据密封状态采取的措施：

Applying neutral gas with 1．5 barg  pressure to all gases and cooling fluid compartments simultaneously and  seeking any leakage to ambient．

Applying neutral gas with 1．5 barg  pressure to cooling fluid compartment and investigating any leakage to  ambient or H2 and air compartments．

Applying neutral gas with 500 mbarg  pressure to each of H2 and air compartments individually and investigating  any leakage to another compartment．

If the leakage is less than 20 ml／min，  then anything is Ok．

If the leakage is between 20 ml／min up to  100 ml／min， then the stack could work but leakage source should be found otherwise  the power output of the stack will be decreased over time．

If the leakage is more than 100 ml／min  then the stack should be disassembled for finding source of leakage．