Analytical Geometrical Model of Open Cell Foams with Detailed Description of Strut‐Node Intersection

Abstract

Open cell foams are regarded as potential enhanced catalyst carriers due to their high specific surface areas, low pressure drops, and good heat and mass transfer rates. However, it is difficult to evaluate their surface area. An analytical model is proposed, which is derived entirely from geometrical hypotheses and can be applied using different easily accessible input parameters. It can accurately estimate the specific surface and other features of foams for a wide range of porosities. The application of the new model to the reevaluation of published gas/solid mass transfer data is demonstrated.

Additive manufacturing of architected catalytic ceramic substrates based on triply periodic minimal surfaces

“…Until recently, the most adopted substrate design for modern catalytic supports has the shape of a honeycomb structure (see Figure A) which despite being simple to fabricate, it has several drawbacks . Therefore, several studies suggested modifying the substrate design to enhance the flow and thermal characteristics which eventually leads to improving the conversion efficiency . For example, stochastic foams (see Figure B) have shown promising advantages in terms of chemical activity over the traditional honeycombs mainly due to the exhibited tortuous flow paths that enhance turbulence .…”

“…1 Therefore, several studies suggested modifying the substrate design to enhance the flow and thermal characteristics which eventually leads to improving the conversion efficiency. [1][2][3] For example, stochastic foams (see Figure 1B) have shown promising advantages in terms of chemical activity over the traditional honeycombs mainly due to the exhibited tortuous flow paths that enhance turbulence. 4 However, the increased chemical activity is usually counterbalanced by an increase in pressure drop across the catalytic substrate.…”

Recent Advances in Structured Catalysts Preparation and Use in Water-Gas Shift Reaction

“…With the aim of evaluating the foam geometry influence on transport phenomena, also Ambrosetti et al [88] developed a model for the estimation of the specific surface area of open-cell foams as a function of either cell diameter and porosity or pore diameter and porosity. Deep comprehension of heat and mass transport phenomena could be also useful in process intensification of exothermic equilibrium reactions, such as WGS processes, in which, a heat redistribution along the catalytic bed, would allow reducing both kinetic limitations at the bed inlet, and thermodynamic limitations at its outlet [89].…”

The Influence of the Washcoat Deposition Process on High Pore Density Open Cell Foams Activation for CO Catalytic Combustion

“…Sh is the Sherwood number, k m is the mass transfer coefficient, L c is the characteristic length, which accordingly to Bracconi et al [2] is the average strut diameter, D is the diffusion coefficient of CO in the gas phase, k v is the volumetric mass transfer coefficient, and S v is the surface-to-volume ratio of the foams evaluated with the model of Ambrosetti et al [1].…”

“…They are constituted by a network of fully interconnected solid struts and open pores that are permeable to flow. These materials typically present high porosities of up to 95% and relatively high surface areas which are inversely proportional to their cell size [1]. In contrast to honeycombs, the flow field inside open cell foams is more complex, since a continuous formation/disruption of the boundary layer is present.…”