A review of gas diffusion layer properties and water management in proton exchange membrane fuel cell system

Author(s):  
Paul C. Okonkwo ◽  
Clement Otor
Author(s):  
Zhongying Shi ◽  
Xia Wang ◽  
Laila Guessous

The gas diffusion layer (GDL) plays an important role in maintaining suitable water management in a proton exchange membrane fuel cell. The properties of the gas diffusion layer, such as its porosity, permeability, wettability, and thickness, are affected by the shoulders of the bipolar plates due to the compression applied in the assembly process. Compression therefore influences the water management inside fuel cells. A two-phase fuel cell model was used to study the water management problem in a proton exchange membrane fuel cell with interdigitated flow channels. The effect of the compression on the fuel cell performance was numerically investigated for a variety of GDL parameters. This paper focuses on studying the water management of fuel cells under compression for various types of gas diffusion layers. First, the deformation of a gas diffusion layer due to compression applied from the shoulders of the bipolar plates was modeled as a plain-strain problem and was determined using finite element analysis (FEA). The porosity and the permeability of the gas diffusion layer were then recalculated based on the deformation results. Next, the deformed domain from the FEA model was coupled with a fuel cell model, and the effects of the compression during the assembly process on the water management and fuel cell performance were studied for gas diffusion layers with different thicknesses, porosities, and compressive moduli. It was found that the deformation of the GDL results in a low oxygen concentration at the reaction site. The saturation level of liquid water increases along the flow direction, and is higher when the compression effect is considered in the simulation.


Author(s):  
Surajudeen O. Obayopo ◽  
Tunde Bello-Ochende ◽  
Josua P. Meyer

Fuel cell technology offers a promising alternative to conventional fossil fuel energy sources. Proton exchange membrane fuel cells (PEMFC) in particular have become sustainable choice for the automotive industries because of its low pollution, low noise and quick start-up at low temperatures. Researches are on-going to improve its performance and reduce cost of this class of energy systems. In this work, a novel approach to optimise proton exchange membrane (PEM) fuel cell gas channels in the systems bipolar plates with the aim of globally optimising the overall system net power performance at minimised pressure drop and subsequently low pumping power requirement for the reactant species gas was carried out. In addition, the effect of various gas diffusion layer (GDL) properties on the fuel cell performance was examined. Simulations were done ranging from 0.6 to 1.6 mm for channel width, 0.5 to 3.0 mm for channel depth and 0.1 to 0.7 for the GDL porosity. A gradient based optimisation algorithm is implemented which effectively handles an objective function obtained from a computational fluid dynamics simulation to further enhance the obtained optimum values of the examined multiple parameters for the fuel cell system. The results indicate that effective match of reactant gas channel and GDL properties enhance the performance of the fuel cell system. The numerical results computed agree well with experimental data in the literature. Consequently, the results obtained provide useful information for improving the design of fuel cells.


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