Estimation of the effective thermal conductivity of carbon felts used as PEMFC Gas Diffusion Layers

Thermal conductivity of gas diffusion layers (GDL) used in fuel cells is a key parameter for the analysis of heat transfer in membrane electrodes assembly (MEA). In this paper, we focus on non-woven carbon felts. Although correlations are available, the felts thermal conductivity is difficult to estimate due to the nature of heat transfer in porous and fibrous materials: the effective conductivity of the solid phase is roughly known and the correlations giving effective conductivity of porous media (solid and fluid phases) have restricted range of application. Consequently, we chose to associate an analytical and an experimental approach. Their results converge and clearly show that the majority of values encountered in the literature are, most probably, highly overestimated.