Durability Study Of Proton Exchange Membrane Fuel Cell Base On Traction Conditions Of Locomotive

Proton exchange membrane fuel cell(PEMFC),as a kind of power generation device that can directly convert chemical energy into electric energy,has the characteristics of environmental protection,high efficiency and low weight,and can be used in portable electronic products,small centralized power supply and distributed power supply systems.However,there are two main reasons limiting the commercialization of PEMFC at present: one is the high production cost and the other is the short service life.The service life of PEMFC is affected by operating conditions such as temperature,humidity and pressure during operation.In this paper,the degradation of PEMFC stack under traction conditions of locomotive is studied.First of all,this paper takes the 5k W high-power PEMFC stack as the research object,especially for traction conditions of locomotive,carries out the PEMFC decay experiment,and studies the decay phenomenon of the stack in the experimental process.It is found that traction conditions of locomotive has a great influence on the decline of the stack.The open-circle voltage of the stack increases and the polarization curve shows a nonlinear decline,which directly affects the service life of the stack.Secondly,based on the polarization curve and electrochemical impedance spectrum,the unevenness of the decay of PEMFC on the single cell in different positions is studied.It is found that the polarization curves of PEMFC at different locations have different declining trends,which indicates that the single cell of PEMFC stack have inconsistent declining due to traction conditions of locomotive.Based on electrochemical impedance spectrum found ohmic resistance also showed the increase of inconsistency,the degradation of ohmic resistance and the position of single cell has obvious relevance,show that different working environment of single cell has a great influence on membrane degradation,in addition,as can be seen from the voltage fluctuation rate,with the increase of operation time,intensify the unbalance of single cell,This unbalanced attenuation trend forms the "bucket effect" which directly affects the service life of the stack.Finally,based on the above durability experimental data,a semi-empirical decay model of the stack and the single cell is established.The research shows that the polarization curves measured by the experiment are almost consistent with the polarization curves obtained by the model,which verifies the accuracy of the established model.On this basis,the polarization curve of 250 h is predicted by using the durability test data of the first 200 h.The results show that the established model is basically consistent with the actual stack decay data,which verifies the accuracy of the decay model.Based on the model,the polarization curves of each single cell were fitted.It was found that when the first cell was in 150h-200 h,the membrane decay played a dominant role,and the degradation mechanisms of the other operating time acted together,indicating that the same single cell had different main degradation mechanisms at different operating time.