Discrete-Particle Model to Optimize Operational Conditions of Proton-Exchange Membrane Fuel-Cell Gas Channels

Abstract

Operation of proton-exchange membrane fuel cells is highly deteriorated by mass transfer loss, which is a result of spatial and temporal interaction between airflow, water flow, channel geometry, and its wettability. Prediction of two-phase flow dynamics in gas channels is essential for the optimization of the design and operating of fuel cells. We propose a mechanistic discrete particle model (DPM) to delineate dynamic water distribution in fuel cell gas channels and optimize the operating conditions. Similar to the experimental observations, the model predicts seven types of flow regimes from isolated, side wall, corner, slug, film, and plug flow droplets for industrial temporal and spatial scales. Consequently, two-phase flow regime maps are proposed. The results suggest that an increase in water accumulation in the channel is related to the increase in the water cluster density emerging from the gas diffusion layer rather than the increased water flow rate through constant water pathways. From a modeling perspective, the DPM replicated well volume-of-fluid channel simulation results in terms of saturation, water coverage ratio, and interface locations with an estimated 5 orders of magnitude increase in calculation speed.

Water cluster characteristics of fuel cell gas diffusion layers with artificial microporous layer crack dilation

“…The angle between the normal vectors was calculated as the contact angle. The code was tested against an artificial droplet with varying contact angles, calculated using the radius of curvature change [1]:…”

“…1(a)). Understanding the development of discrete water clusters in this system which form as a consequence of the surrounding materials is important for design and operation of fuel cells [1]. Therefore, the coupling between the gas diffusion layer (GDL), gas channel (GC) and microporous layer (MPL) is important because the interfaces can facilitate or hinder mass transport of oxygen to reach the catalyst layer [2,3].…”

“…Water clusters in the GDL provide the pathways of water flow to the gas channel flow fields [1,[6][7][8][9][10]. They also control water removal from catalyst layer which can cause oxygen starvation, flooding, nonuniform current distribution and degradation.…”

“…However, the impact of crack area fraction on water accumulation in the GDL has not been studied. Each discrete water cluster emerging from these MPL cracks has its own phase pressure [18,22,35] and the water cluster density, defined as the number of water clusters per in-plane area of material is important for flooding in the channels and water covering the GDL for oxygen transport [1]. This interaction of the GDL-channel interface cannot be ignored, as the water covering the GDL surface blocks oxygen transport [1,36,37].…”

Energy Internet System Based on Static Security Analysis of Multi-Energy Flow

“…The goal is to minimize unnecessary losses and analyze failures as quickly as possible. The aim is to eliminate the most "harmless" bugs in a short period of time and without missing any vulnerabilities [12][13].…”