Evaluation and Optimization of Flow Distribution in PEM and DMFC Fuel Cells

摘要

In order to effectively utilize the entire area of the anode and cathode, as homogeneous a flow distribution as possible is required so that the reactants are distributed homogeneously in the fuel cell. The objective of this presentation is to study the influence of different flow field structures and various manifold designs on the flow distribution and performance of DMFC and PEM fuel cells. The testing of the anode flow field was carried out in a two-phase flow test rig whereas the cathode evaluation was single phase only. The flow field area was in both cases 600cm~2. The flow distribution depends strongly on the geometry and the flow rate of the reactants. The experiments were fitted by simulations using the CFD package FLUENT. Additional effects on the flow distribution are caused by bubble formation of CO_2, which was investigated in detail. Furthermore, different combinations of flow fields were tested in single PEM cells under real fuel cell conditions. Experiments show a dependence of the ohmic resistance on the contact area. Humidification of the anode is necessary to obtain stable operation. Thermal investigations on cells under working conditions using an IR camera show the influence of flow field structures on the thermal management of DMFC cells.