BACKGROUND:The development of new open-cell porous electrodes for electrochemical flow cells and reactors is demonstrated through the application of 3D printing. The properties of diverse architectures were investigated, including rectangular, circular, hexagonal and triangular cells with linear porosity grades of 10, 20 and 30 pores per inch (ppi). Specimens were digitally designed, then 3D printed in stainless steel via selective laser melting. After being examined using scanning electron microscopy, they were characterized in terms of volumetric surface area and porosity with the aid of X-ray computed tomography. Pressure drop measurements were performed over a range of mean linear velocity and Reynolds number, allowing the estimation of Darcy's friction factor and permeability.RESULTS: Volumetric surface area estimated from tomography scans was ≤36% higher than the nominal values owing to surface roughness and post-processing algorithms. By contrast, volumetric porosity obtained by tomography agreed fully with measured values. Triangular architectures afforded additional surface area both digitally and according to tomography. The largest pressure drop was found in circular materials, the triangular ones showing the lowest. The 20 ppi triangular architecture had a volumetric surface area of ≈44.5 cm −1 and a permeability of 2.31 × 10 −5 cm 2 . CONCLUSION: Triangular architectures were preferred as a consequence of their favourable combination of high surface area and high permeability with low mass and reduced digital complexity. This provides a strategy to initiate the optimization of 3D printed porous electrodes for electrochemical flow cells and reactors in novel and niche applications.
This study is aimed to compare the performance of four Reynolds Averaged Navier Stokes (RANS) turbulence models in simulating complex flow over two- and three-dimensional (2D and 3D) cubic geometries using experimental measurements for model validation. The four turbulence models were k-Epsilon (k-ε), k-Omega (k-ω), Shear Stress Transport (SST) and BSL Reynolds Stress (RSM) models. The model validation was performed by comparative analysis with the experimental values of pressure coefficient around the cubic geometries. It was found that the SST and BSL RSM models performed better than the others in capturing the complex separated flows and strong shear in the boundary layer. The good agreement with empirical data can be attributed to the inclusion of transport effects of turbulence and the anisotropic nature in the formulations of the models.
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