Study And Optimization Of Output Characterristics Of Water-cooling PEMFC

Whether the proton exchange membrane fuel cell(PEMFC)can output power in a stable,efficient and sustainable manner is the key to commercialization.This paper focuses on the research and optimization of dynamic output performance of proton exchange membrane fuel cell.In this paper,the dynamic output performance of water-cooling PEMFC single cell is studied by using the 890e PEMFC single-cell test system provided by Scribner Corporation in USA.And the dynamic output performance of water-cooling PEMFC stack is studied by using the SP-FCT-30K fuel cell test system provided by Sunrise Power Co.,Ltd.At the same time,the corresponding optimization strategies are put forward for the two research objects.The main research contents are as follows:(1)This paper studies variation of the dynamic performance of water-cooling PEMFC single cell under the different hydrogen starvation and oxygen starvation.Research results show that the oxygen starvation has a significant effect on the performance of water-cooling PEMFC single cell.When the air stoichiometry is small,the polarization curve is decrease rapidly and the maximum power density decrease with the output current increasing,meanwhile the performance of the single cell decays.Hydrogen starvation has little effect on PEMFC single cell.(2)The influence of four operating conditions on the electrochemical impedance of water-cooling PEMFC single cell was investigated by using the electrochemical impedance spectroscopy(EIS).The experimental results showed that the effect of cathode stoichiometry on water-cooling PEMFC single cell from obvious to inapparent was high frequency impedance,temperature and humidification temperature,anode stoichiometry when the current density of water-cooling PEMFC single cell was 1400 mA/cm~2.The fitting curve of the equivalent circuit has a certain deviation from the actual operation curve,the maximum absolute error of each impedance is 2.1609 m?,and the maximum relative error is 46.6%.However,the equivalent circuit can accurately determine the relationship between the impedance values and the corresponding change trend,which can better replace the experimental results.(3)For the optimization of the output performance of the water-cooling PEMFC single cell,the current short circuit,current perturbation and air flow disturbance are used to optimize the performance of the method.Experiments have found that all three methods can effectively improve the output performance of water-cooling PEMFC single cell.Especially,the current short circuit can effectively improve the output performance of water-cooling PEMFC single cell,especially in the case of high current.The maximum output voltage can be increased by 0.17 V,and the output power can be increased by 8.56 W.(4)For water-cooling PEMFC stack,the effects of temperature and oxygen starvation on its dynamic performance was investigated.The results show that the optimum temperature of the stack is closely related to the size of the load.As the oxygen starvation deepens,the output voltage of the water-cooling PEMFC stack decreases.The output performance is reduced and the voltage fluctuations is increasing.(5)To optimize the performance of water-cooling PEMFC stack,this paper put forward a method to improve the performance of water-cooling PEMFC stack by using short-time oxygen starvation,and study the effects of short-time oxygen starvation on the performance of water-cooling PEMFC stack from three aspects:auxiliary load current,starvation levels and the maintenance time of short-time oxygen starvation.The results show that,lower decreasing degree of short-time oxygen starvation,higher auxiliary load current value,and the relatively longer maintenance time of short-time oxygen starvation,which can result in more obvious improvement of the fuel cell performance and longer maintenance time of improved performance when the maintenance time is selected as 10s.