Increasing the Efficiency of High Temperature PEM Fuel Cells by Using Simulated Optimized Flowfields

摘要

Numerical simulations of complex systems, e.g. the characteristics of chemical reactions, open new possibilities for enhancing the effectiveness of fuel cells. With an appropriate approach it is possible to simulate the interactions between anode and cathode and to predict the flow distribution of each gas. With respect to the velocity distribution in each flow-channel it is important to calculate all reaction products realistically. User defined program modules, which are integrated into the commercial software Ansys CFX, allow obtaining detailed information on the flow distribution in the flow channels. Simulation results show a nearly realistic distribution in the MEA. The volume fractions of the different gases in the channels correspond to reality, while, at the same time, the total system is in good electrochemical balance. With this program it is possible to simulate complex designs or even stacks on standard workstations. In the case of high-temperature PEM fuel cells, which operate at temperatures of approx. 130-180 °C, the calculation of water saturation or water content can be neglected. Designing a new, optimized flow field requires meeting the conflicting requirements of uniform gas distribution, good electrical contact and an overall low pressure drop simultaneously. With the new simulation program it is possible to develop and construct flow field designs with higher efficiency and better performance than the standard meander or pin-structure geometries.