Study on Water Management of Polymer Electrolyte Fuel Cell (3rd Report, Influence of Gas Channel Height on Water Transportation in PEFC Cell)

Abstract

We have experimentally investigated influences of cathode channel heights on vapor permeation flux through gas diffusion layer (GDL) of polymer electrolyte fuel cell (PEFC). Vapor permeation flux through GDL was remarkably influenced by channel velocity. In the analysis of these experiments with a vapor transport model, it was shown that the resistance associated with the vapor-concentration boundary layer was dominant in the low channel velocity less than 0.5m/s, and the resistance for the diffusivity of GDL became dominant as channel velocity increases. Influences of the channel height on the vapor permeation flux were verified by the power generation tests using a single cell. In the cell tests, anode channel height was fixed at 0.5 mm and cathode channel heights were changed at 0.2 mm, 0.5 mm, 1 mm and 3 mm. Under the high humidity condition, the cell performance was improved by using a separator with the shallow channel height. Such a cell performance was well correlated with the vapor permeation flux through GDL. In addition, influences of oxidant utilization and water management layer (WML) on the cell performance were evaluated.