3-D Multiphase Cold Start Model for PEMFCs

A three-dimensional multiphase model has been developed to simulate the cold start processes in a polymer electrolyte membrane fuel cell (PEMFC). This model uniquely includes the water freezing in the membrane, the non-equilibrium mass transfer between the water in the ionomer and the water (vapour, liquid and ice) in the pore region of the catalyst layer (CL), and the water freezing and melting in the CL and gas diffusion layer (GDL). Numerical simulations have been conducted for a single PEMFC starting from different subzero temperatures to investigate both the failed and successful cold start processes. Numerical results indicate that the ohmic heat is the largest heating source at low cell voltages. It is observed that water freezes first in the cathode CL under the land, and ice melts first in the CLs under the flow channel, the melted water in the anode is also removed faster than in the cathode.