150hr强化道路振动工况实验下车载燃料电池电堆的不同电流下各极化损失的变化

An investigation of characteristicparameter variations of the polarization curve of a proton exchange membranefuel cell stack under strengthened road vibrating conditions

Yongping Hou

Binglong Zhou

Wei Zhou

Caoyuan Shen

Yuntang He

Abstract

The characteristic of the polarizationcurve and the parameter variations of open circuit voltage V0， Tafel slope band ohmic resistance R in the curve are experimentally investigated through a150 h strengthened vibration test in this paper， to analyse the steady－stateperformance of the fuel cell stack under long－term vibrating conditions onstrengthened roads． The load spectra applied in the test are simulated by theacceleration signals of the fuel cell stack， which are previously measured in avehicle vibration test． The load signals of the vehicle vibration test areiterated through a road simulator from vehicle acceleration signals which areoriginally sampled in the strengthened road of the ground prove． During the test， the current and voltageunder steady－state operation of the stack were measured six times at regularintervals． The test results indicate a fluctuating variation of thepolarization curves． In the meantime， theV0 decreases by 3％ of the original value， R increases by 55．8％ and b declinesby 28．0％． From the results it can be concluded that the strengthened roadvibration exert a significant influence on the steady－state performance of thefuel cell stack， which cannot and should not be ignored during the research．

The 45 kW FC power module used here are  consists of a stack with 560 cells assembled in series． The effective  membrane area per cell is 280 cm 2 ．

Fig． 1 e The six－channel multi axial  simulation table used in the 150 h strengthened vibration test．

Fig． 2 e Schematic of the FC test bench．

Fig． 3 e Location of the accelerometers  on the FC stack．

Fig． 4 e Variation of the polarization  curve during the vibration test． Marker＝test data； line ＝fitting curve； cyan＝the  polarization curve after the test duration of 0 h； red＝the polarization curve  after the test duration of 26 h； blue＝the polarization curve after the test  duration of 62 h； green＝the polarization curve after the test duration of 72  h； brown＝the polarization curve after the test duration of 123 h； purple＝the  polarization curve after the test duration of 150 h．

性能差异并不大，而且150hr高电流密度下的性能还有所上升。

Table 1 e Parameters of polarization  curves fitted from experimental data．

Fig． 5 e Variation of V 0 during the  vibration test． Blue diamond＝V 0 during the vibration test； dash－dot line＝the  fitting curve of V 0

Fig． 6 e Variation of b during the  vibration test． Blue diamond＝b during the vibration test； dash－dot line＝the fitting  curve of b．

Fig． 7 e Variation of R during the  vibration test． Blue diamond＝R during the vibration test； dash－dot line＝the fitting  curve of R．

Conclusion

The following conclusions can be obtained  through the analysis of this paper：

1． The strengthened road vibration has a  significant influence on the performance of polarization curves． A  fluctuating variation of the polarization curves is observed in this paper．  The inherent laws and detailed reasons for such fluctuating variation need  further investigation．

2． In the strengthened vibration test，  the three key characteristic parameters from polarization curves vary as follows：（1）  the OCV （V 0 ） presents a downward trend with the increase of the test duration．  It decreases at the rate of 0．078 V／h and experiences a drop of 3％ of the  initial value；

（2） Tafel slope b decreases monotonically  at the rate of 0．044／h and drops finally to 72．0％ of the initial value after 150  h strengthened vibration test；

（3）the ohmic resistance R rises  approximately linearly at the rate of 0．001 Ω／h during the test and  ultimately reaches a growth of 55．8％．

3． The strengthened road vibration has a  significant influence on the steady－state performance of the FC stack， which cannot  and should not be ignored during the research． As this paper is just a preliminary  test result， the internal mechanism of the influence of the strengthened road  vibration on the FC stack requires further investigation．