Study Of Proton Exchange Membrane Fuel Cells Performance And Power Supply System

Proton exchange membrane fuel cells (PEMFC) as a chemical battery can change directly chemical energy into electrical energy, as with the feature of high efficiency for energy changing, of no contamination to environment. Therefore, It was to pay close attention to. Now the study on PEMFC have been there research torrid zone of fuel cells. Many developed countries have fling great found to the research field. Up to now the study on the PEMFC have taken great achievement in all over the world, and begin to spread use it in some important field. Our country already contain more and more research unit to proceed proton exchange membrane fuel cells and its power supply system research and develop.The fuel cell's characteristics and classification and the technique characteristic of the every kind of fuel cell are summarized in the first chapter. As the representative of the fourth generation of generating electricity, PEMFC is widely recognized as the new generation of power source to compete with internal combustion engine.In chapter 2, mainly describes the function principle of the PEMFC, the key materials of PEMFC: including proton exchange membrane (PEM), electrocatalyst, electrode and bipolar plates are introduced, the basic fundamental and the state-of-art of the key materials at home and abroad are described, the composition of fuel cell system, and the utilization of PEMFC on power supply system. This chapter finally outlines the problems of PEMFC development and commercialization.The theory of PEMFC was simply analyzed in chapter 3. The dissertation also systematic investigate the effect of PEMFC operation parameter. The investigate show that the PEMFC operation temperature is an important parameter of effect on the discharge performance of PEMFC. In a certain range of temperature, the higherthe temperature of the PEMFC operation, the better the discharge performance of PEMFC. The gas pressure and flow number also influence on the discharge performance of PEMFC. Especially the oxygen pressure and flow number show more intense. The test result show that the alter of gas adding moisture temperature has also effect on the discharge performance of PEMFC, and the effect is more intense after the adding moisture temperature higher than the PEMFC operation temperature.Such measures as followed were taken in the system. Ordinary-press air was adapted to act as the oxidizer, and the velocity of airflow and its gross were controlled by DC timing fans; Reversible metal hydrogen-storing material was adapted to store and supply hydrogen. The flux of hydrogen supplying was confined to the max-loading condition by a flow-limit valve and the press was stably provided by two grade of decompression. At the mean time, the waste heat of the fuel cell stack and the heat dispersed by the electrical system were utilized to maintain the hydrogen storage's working temperature. The method of "felt sopping water" and "water bottle bubbling " were separately used to humidify the air and hydrogen at the same time, and the amount of humidifying water were separately controlled by timing supplying and temperature regulating by the heat of the electrical system. The feasible working temperature of the cell stack was maintained by utilizing the structure designing in the machine box and the adjusting of rotate speed of the fan. The superfluous gas was let by the method of interval exhausting. Lastly we integrated the whole system, and tested the system's each performance parameter. The result indicated that the designing of the system and had achieved the predetermined goal and have strong pertinence and practicability.