Volume 2: Innovative Solutions for Energy Transitions: Part I

Empirical Modelling of Pressure Drop in Gas Channels of Polymer Electrolyte Fuel Cells Zan Wu

Abstract

The frictional pressure drop characteristics in gas channels of Polymer Electrolyte Fuel Cells (PEFCs) are modelled in this work. The two-phase flow in gas channels of PEFCs has its special features: (1) combination of reactant gas, water vapor and liquid water, (2) flow in micro/mini channels, (3) reactant consumption, (4) condensation from water vapor, (5) continuous water introduction from reaction and (6) flow pattern transitions. Therefore, previous two-phase pressure drop correlations, primarily for adiabatic gas liquid flow, might not be able to capture the pressure drop in the gas channel with a porous wall. The new flow pattern based pressure drop method covers three major flow regimes in gas channels, i.e., the single-phase gas flow zone, and droplet/mist flow and slug/film flow in the two-phase flow zone. In the droplet/mist flow regime, a homogeneous flow modelling was adopted, while in the slug/film flow regime, a modified Chisholm value of 8.5 was used. The new predictive tool presents improved accuracy in pressure drop estimation for different current densities and stoichiometric ratios of operating PEFCs.

Keywords Pressure drop, two-phase flow, polymer electrolyte fuel cell, flow pattern, slug/film flow