An Analytical Solution to Predict the Inception of Two-Phase Flow in a Proton Exchange Membrane Fuel Cell

Abstract

The presence of liquid water at the cathode of proton exchange membrane fuel cell hinders the reactant supply to the electrode and is known as electrode flooding. The flooding at the cathode due to the presence of two-phase flow of water is one of the major performance limiting conditions. A pseudo-two-dimensional analytical model is developed to predict the inception of two-phase flow along the length of the cathode channel. The diffusion of the water is considered to take place only across the gas diffusion layer (GDL). The current density corresponding to the inception of two-phase flow, called the threshold current density, is found to be a function of the channel length and height, GDL thickness, velocity, and relative humidity of the air at the inlet and cell temperature. Thus, for given design and operating conditions, the analytical model is capable of predicting the inception of two-phase flow, and therefore a flooding condition can be avoided in the first place.