MICROCANAIS BIOINSPIRADOS OTIMIZADOS PELO ALGORITMO SLIME MOLD APLICADOS À DISTRIBUIÇÃO DE REAGENTES EM CÉLULAS A COMBUSTÍVEL DO TIPO PEM

Abstract

The performance of proton exchange membrane fuel cells (PEMFCs) depends on how efficiently the reactants are distributed along the channels of the bipolar plates, since poor gas distribution produces regions of low renewal, mass transport losses and increased pressure drop. This work evaluated, through computational fluid dynamics (CFD), a bioinspired microchannel geometry based on pulmonary branching and optimized by an algorithm inspired by the behavior of Physarum polycephalum, known as Slime Mold, comparing it with a conventional parallel channel geometry. The geometries were generated in Python, adjusted in CAD software, exported as STL files at the millimeter scale, discretized in OpenFOAM with blockMesh and snappyHexMesh, and simulated with the simpleFoam solver, considering single-phase, incompressible and isothermal air flow. Six cases were studied, combining the two geometries with three operating conditions: a flow rate of 2 𝐿 ⋅ 𝑚𝑖𝑛−1(realistic condition), a flow rate of 5 𝐿 ⋅ 𝑚𝑖𝑛−1 (high-flow condition) and a pressure difference from 200 kPa to 100 kPa (pressure sensitivity analysis). Under the realistic condition, the bioinspired geometry presented a pressure drop of 1.198 kPa against 0.639 kPa for the conventional geometry, both in laminar regime (Re ≈ 1586 and 1599). Under the high-flow condition, the pressure drops were 5.696 kPa and 3.078 kPa, respectively. Under elevated pressure, the conventional geometry carried 158.70 𝑚3 ⋅ 𝑠−1 against 135.43 𝑚3 ⋅ 𝑠−1for the bioinspired one. The conventional geometry therefore presented lower hydraulic resistance under all evaluated conditions, while the bioinspired geometry demonstrated the methodological feasibility of generation, discretization and simulation, but still requires smoothing of the bifurcations, channel resizing and hydraulic equalization of the flow paths. It should be emphasized that the comparison is strictly hydraulic, without a gas diffusion layer, liquid water or electrochemical coupling, so the results do not represent the complete electrochemical performance of a PEMFC.