Study On Dynamic Response Of Proton Exchange Membrane Fuel Cell

Based on the condition of complex dynamic load changes, the influence of vehicle fuel cell. Because of its dynamic characteristics, fuel cells dynamic output in a certain extent affect cell performance and life. This paper aims to study in PEMFC single cell dynamic load change the dynamic characteristics. This test method through transient, theoretical analysis of proton exchange membrane fuel cell, various aspects of dynamic response characteristics were studied. Study the load type and loading and various operation conditions of such causes of proton exchange membrane fuel cells, the influence of dynamic response analysis combined with oxygen in the air/contrast experiment, and the dynamic load current density distribution test of proton exchange membrane fuel cell cause of dynamic response. Finally, using the basic step of proton exchange membrane fuel load test cell life. To put forward the dynamic load of proton exchange membrane fuel cell, the main effect influence life. The main research contents and the conclusions are as follows:(1) Different types of fuel cell loading, the response characteristics of load is different. The same step, load current PEMFC pure resistance loaded than loading pure perceptual load response time is shorter, low-key. When loading the pure inductance load and step 200mA/cm2, current response time is about loading pure resistance loaded when 4 times, low-key quantity is approximately loading pure resistance loaded when around 4 times. Pure resistance loaded more suitable for fuel cell characteristics. Regardless of what load, as load increases, the current step response time and low volume will increase. Loading pure resistance loaded, fixed voltage when the cell is low load for 0, and when fixed load current, cell will appear larger low-key value. Both to fixed load current response time. Therefore fixed voltage loading mode is fixed load current more optimal model.(2) cathode gas chemical measurement, cathode humidifying humidity and current density of step size is PEFC dynamic response is the most important impact on performance of the three parameters. Therefore PEMFC dynamic response caused mainly by the limited. When the cathode air chemometrics in more than 3, than the current density low, no obvious difference PEMFC low-key, high current density, because the water area of accumulation, still have bigger difference, the current density of the difference between the Laplace domain. The cathode air humidifying humidity too low or too high dynamic response of PEMFC can cause considerable changes, the dynamic response of the performance of PEMFC in less than 50% but will reach 100% humidifying, a very good dynamic performance.(3) when the air with oxygen/low gas chemical measurement than 1.2 contrast test, air high current density area, the instantaneous gas evident in the lowest voltage appears negative. Oxygen is low-key almost no with current density increases, the Laplace domain has been maintained in low-key 0.03 V, response time in 0.022S～S between increase with. But the air during test, low-key and response time with current step increase obviously increased in value and low linear 0.03 V～0.45 V, response time between 0.1～～S in the 20S. When the air with oxygen flow at low oxygen, still remain in tone contours, but excessive 0.03 V cell destroyed the oxygen in water balance, the response time increase greatly. With oxygen concentration increases, the dynamic response low-key PEMFC, and response time then linear decrease.(4) steady-state current density uneven mainly appear in import and export and active area edge regions. General maximum and minimum size for the current density of six times. Dynamic load current, import and export and edges exacerbates the inhomogeneity of the lowest and highest, the ratio of current density of 14 times. The highest average current density in active area middle area. And as the highest current density area with gas and water quality management of expanding or shrinking management. The dynamic load, its loading a funnel non-uniformity of import and export, and the uneven around the middle area, and the lowest level, high ratio of 6-10 times.(5) initial performance is very good and single chip is 0.69 V:600mA/cm2＠, but after this cycle,12,000 average single cell performance:0.63 V/cm2＠600 mA, working voltage attenuation:1.5 muon V/es, better than GM test results, but the distance from 5,500 hours, catalyst life there is still significant loss or reunion. OCV attenuation:2.5 muon V/es than working voltage, large, therefore film in the attenuation under high voltage of corrosion is also very serious problem. Electric voltage consistency of the standard deviation of 10,000 times by double loop,16mV reach. Increased temperatures to HFR import and export, influences the performance of single chip, therefore the discussion above should be based on different VIR-. The attenuation of proton exchange membrane in PEMFC dynamic load conditions of electricity attenuation of membrane thinned, due to the increase and crossover caused more than the pinhole, catalysts and other components, therefore, the attenuation of proton exchange membrane attenuation of dynamic load power is an important factor of the attenuation.