Abstract
Since the Gas Diffusion Layer (GDL) clearance and the residence time of produced water in gas channels remarkably affect the proper operation of proton exchange membrane (PEM) Fuel Cells, the water management in this part plays a key role. To this end, the present study aims to introduce novel and optimized gas channels through geometrical modifications that act efficiently in terms of GDL clearance and liquid residence time. For this purpose, the VOF (Volume of Fluid) model was employed to numerically simulate two-phase flow by means of a finite volume method. Several decisive parameters including superficial gas velocity, channel surface wettability, and channel cross-section geometry were considered to find their effects on the liquid removal behavior. The liquid removal performance was analyzed by two-phase pressure drop, area coverage ratio (ACR), and liquid removal time. Results have been compared with previous works done on the conventional rectangular channels. Interestingly, it was found out that for the analyzed segment of the gas flow channels, the channel with triangle cross-section has superior performance in reducing ACR by 64% for inlet superficial air velocity of 0.5 m = s and 8-24.45% reduction for higher velocities (1, 1.5 and 2.5 (m)/s). Also, the transition from slug flow to film flow also stable two-phase pressure drop were only seen in this type of channel. The ranking of channels based on their residence time merit is as: hexagon > pentagon > rectangular > triangle. Increment of the contact angle of hydrophilic walls causes fluctuations in the two-phase pressure drop and decreases liquid water residence time. For triangle channel, surface with a contact angle of similar to 120 degrees and for the hexagon and pentagon channels 85-120 degrees is suggested for the best fuel cell performance. (c) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.