A new model for thermal contact resistance between fuel cell gas diffusion layers and bipolar plates

• Optical images show that GDL fibers are wavy and not straight.
• Thermal contact resistance (TCR) decreases with fiber wavelength.
• TCR increases with curvature, diameter and amplitude of fiber and GDL porosity.
• TCR does not change with fiber length.
• TCR variations with geometric parameters are higher at lower compression.

A new analytical model is developed to predict the thermal contact resistance (TCR) between fibrous porous media such as gas diffusion layers (GDLs) of polymer electrolyte membrane fuel cells (PEMFCs) and flat surfaces (bipolar plates). This robust model accounts for the salient geometrical parameters of GDLs, mechanical deformation, and thermophysical properties of the contacting bodies. The model is successfully validated against experimental data, and is used to perform in a comprehensive parametric study to investigate the effects of fiber parameters such as waviness and GDL properties on the TCR. Fiber waviness, diameter and surface curvature, as well as GDL porosity, are found to have a strong influence on TCR whereas fiber length does not affect the TCR when the porosity is kept constant. Such findings provide useful guidance for design and manufacturing of more effective GDLs for PEMFC heat management.The analytic model can be readily implemented in simulation and modeling of PEMFCs, and can be extended with minor modifications to other fibrous porous media such as fibrous catalysts, insulating media and sintered metals.

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