Insights into the role of wettability in cathode catalyst layer of proton exchange membrane fuel cell; pore scale immiscible flow and transport processes

JOURNAL OF POWER SOURCES

卷:349

Article

Fathi, H.¹  Raoof, A.²  Mansouri, S. H.¹ 

[1] Shahid Bahonar Univ Kerman, Dept Mech Engn, Kerman 7616914111, Iran

[2] Univ Utrecht, Dept Earth Sci, POB 80021, NL-3508 TA Utrecht, Netherlands

关键词: PEM fuel cell;    Cathode catalyst layer;    Two-phase flow;    Wettability;    Effective diffusivity;   

DOI  :  10.1016/j.jpowsour.2017.03.012

来源: Elsevier

【 摘 要 】

The production of liquid water in cathode catalyst layer, CCL, is a significant barrier to increase the efficiency of proton exchange membrane fuel cell. Here we present, for the first time, a direct three-dimensional pore-scale modelling to look at the complex immiscible two-phase flow in CCL. After production of the liquid water at the surface of CCL agglomerates due to the electrochemical reactions, water spatial distribution affects transport of oxygen through the CCL as well as the rate of reaction at the agglomerate surfaces. To explore the wettability effects, we apply hydrophilic and hydrophobic properties using different surface contact angles. Effective diffusivity is calculated under several water saturation levels. Results indicate larger diffusive transport values for hydrophilic domain compared to the hydrophobic media where the liquid water preferentially floods the larger pores. However, hydrophobic domain showed more available surface area and higher oxygen consumption rate at the reaction sites under various saturation levels, which is explained by the effect of wettability on pore-scale distribution of water. Hydrophobic domain, with a contact angle of 150, reveals efficient water removal where only 28% of the pore space stays saturated. This condition contributes to the enhanced available reaction surface area and oxygen diffusivity.(C) 2017 Elsevier B.V. All rights reserved.

【 授权许可】

Free