Effect of Structural Parameters on Mass Transfer Characteristics in the Gas Diffusion Layer of Proton Exchange Membrane Fuel Cells Using the Lattice Boltzmann Method

Abstract

The gas diffusion layer (GDL) is a key component to realize effective gas transport in the electrode of proton exchange membrane fuel cells. To study the effect of different structural parameters on the mass transfer characteristics of the GDL, a developed random reconstruction algorithm is proposed to generate three-dimensional (3D) GDLs with different structures, and the lattice Boltzmann method is used to simulate the flow behavior of reactant gases in the GDL. Through the calculation of the tortuosity and the comparison with the results reported in the references, the accuracy of the model in this paper is demonstrated. The outlet velocity and average velocity of the gas, the gas phase tortuosity, and diffusivity of the GDL are calculated by changing the structural parameters of carbon fiber diameter, porosity, and thickness. It is found that increasing the diameter of the carbon fiber from 7 to 9 μm can increase the reactant gas velocity but has little effect on the improvement of GDL diffusion characteristics. Increasing the porosity from 60 to 80% can significantly increase the reactant gas velocity and improve the diffusion characteristics of the GDL. Increasing the thickness from 112 to 280 μm, the reactant gas velocity is significantly reduced, and the diffusion characteristics of the GDL are weakened, but the change is not obvious. Finally, the influence of GDL structural parameters on electrical conductivity is discussed.

Effect of Binder and Compression on the Transport Parameters of a Multilayer Gas Diffusion Layer

“…In this work, the D3Q19 velocity model was employed to simulate the gas flow in GDL, which means that each node will have 19 possible speeds at time t + 1. The velocity vector ( c i ) is represented as follows: …”

“…The evolution equation and equilibrium distribution function ( f i eq ) of the LBM velocity distribution are expressed as follows: where f i denotes particle velocity distribution function, Δ t is a time step, ω is the relaxation frequency and c s represents the sound speed, which is taken as in D3Q19 model. w i , ρ, and u are the weighting factor, fluid density, and fluid velocity respectively, and they can be expressed as follows: …”

“…The pressure boundary conditions proposed by Zou and He were applied to the inlet and outlet of the computational domain, and periodic boundary conditions were applied to the remaining four surfaces. The specific boundary processing process can be found in our previous work . For the D3Q7 model, the concentration difference between the inlet and the outlet was set to 2 and periodic boundary conditions were applied to the remaining four faces.…”

“…The specific boundary processing process can be found in our previous work. 59 For the D3Q7 model, the concentration difference between the inlet and the outlet was set to 2 and periodic boundary conditions were applied to the remaining four faces. Electrons are conducted in the solid phase, and the bounce-back boundary condition was applied to the pore boundary.…”

Effects of the Structure, Wettability, and Rib-Channel Width Ratio on Liquid Water Transport in Gas Diffusion Layer Using the Lattice Boltzmann Method

“…When hydrogen is used as fuel, proton exchange membrane fuel cells (PEMFCs) are considered high-efficiency, zero-emission, and low-noise energy conversion devices. And they are widely used for portable energy and transportation applications. − …”