Interfacial oxygen transport resistance in a proton exchange membrane fuel cell air channel with an array of water droplets

Abstract

The oxygen (O) transport resistance at the gas diffusion layer (GDL)-air channel interface in a proton exchange membrane fuel cell (PEMFC) is numerically investigated. The interfacial O resistance under the twophase flow conditions is needed in modeling fuel cell performance. This work focuses on simulating the effect of water droplets on the GDL surface on the mass transfer resistance at the interface. Multiple droplets are placed at the center of channel width and spaced uniformly in the flow direction. The variation of interfacial O 2 transport resistance is characterized with the non-dimensional Sherwood number (Sh). The numerical technique is validated by comparing the fully developed Sh (in the absence of droplets) to the established values in the literature. Parametric simulations are performed for variable air Péclet number (varied due to changing superficial air velocity), non-dimensional droplet size and uniform spacing. Correlations are developed to express the Sh variation in terms of the aforementioned variables and the location in the channel. The maximum error of the correlations among numerically generated 999 data points is 11%.

Oxygen transport resistance at gas diffusion layer – Air channel interface with film flow of water in a proton exchange membrane fuel cell

“…Local Sh on the side of a film is expressed with respect to Sh FD,f in Eq. (20). The variation of Sh/Sh FD,f along the flow length resembles the Graetz problem.…”

“…Koz and Kandlikar characterized Sh for the cases where the GDL-air channel interface is covered with droplets [20,21]. However, films have been recognized to occur more frequently in PEMFC air channels [10,11].…”

A review of physics-based low-temperature proton-exchange membrane fuel cell models for system-level water and thermal management studies

“…Finally, it is important to mention that a few authors [11,34,40,58,61] consider a mass transfer resistance between the channel gas flow and the GDL by using Sherwood number correlations, usually valid for fully developed laminar flow, but most neglect it. For two-phase conditions where droplets or films might be present in the channel, Sherwood number correlations are provided by Koz and Kandlikar [99][100][101].…”

Numerical investigation on the nano/microscale transport processes in proton exchange membrane fuel cells: A review

“…Chen等人 [94] 研究了GDL 表面微观结构对界面液滴临界脱落直径的影响, 结果表明, 粗糙表面能够减小脱落直径, GDL进水孔径越大, 液滴脱离直径越大. Koz和Kandilikar [116] 研究了GDL/GC界面液滴对氧气界面传递阻力的影响, 采用Sherwood number表征了传质系数. 上述研究均采用了相对简单的GDL粗糙结构.…”