Micro-porous layer stochastic reconstruction and transport parameter determination

Effective diffusivity of polymer electrolyte fuel cell gas diffusion layers: An overview and numerical study

“…GDLs tested: a set of carbon paper GDLs (MFG-070, AvCarb P50, Toray-120 and SGL 10BB) and carbon cloth materials (SCT-NF2, CARBEL and ELAT-1400). The effective diffusivity of the MPL estimated by Chan et al [17] is one order of magnitude lower than those estimated by Nanjundappa et al [28] and El Hannach et al [35]. It should be noted that the porosity values of the MPLs investigated by the above groups were more or less the same, i.e.…”

“…Likewise, the effective diffusivity of the catalyst layers measured by Shen et al [20] is expected to be highly underestimated. Similarly, the effective diffusivity of the MPL estimated by Zhang et al [34] is lower than those estimated by Nanjundappa et al [28] and El Hannach et al [35] by an order of magnitude. However, the porosity of the MPL investigated by the former group is about 0.3 [34] which is almost half the MPL porosity investigated by the latter group [28,35].…”

“…The MPL thickness was set to 50 mm and consequently the GDL thickness reduced from 250 to 200 mm. Two different values were used for the effective diffusivity of the MPL, namely 0.20 for an MPL with a porosity of about 0.6 [28,35] and 0.04 for an MPL with a porosity of about 0.3 [34]. It should be noted that since the above the used values for the MPL effective diffusivity are experimental, they should be representative of both the molecular diffusion and the Knudsen diffusion [35].…”

“…Two different values were used for the effective diffusivity of the MPL, namely 0.20 for an MPL with a porosity of about 0.6 [28,35] and 0.04 for an MPL with a porosity of about 0.3 [34]. It should be noted that since the above the used values for the MPL effective diffusivity are experimental, they should be representative of both the molecular diffusion and the Knudsen diffusion [35]. Since the overall performance of the modelled fuel cell is significantly over-estimated if the Bruggeman relation is employed, the intuition is to use Equation (5), rather than the Bruggeman relation, to calculate the effective diffusivity of the GDL.…”

A unit-cell approach for determining the effective thermal conductivity of the polymer electrolyte membrane fuel cell microporous layer

“…In particular, the resolution required to effectively model the contact region between particles (a dominant mechanism in thermal conductance between particles [8]) has not been achieved in literature [19,20]. The current models found in literature are based on the stochastic reconstruction of the entire MPL material [9,10,21] or deterministic reconstructions of the MPL based on computed tomography [19,20,22]. The impact of the nature of contact between the particles on thermal conductance has also been studied by the authors group in an earlier work [8], where it was found that the MPL should be modelled with material-specific inputs regarding the particle size and nature of contact.…”