In Search of Governing Gas Flow Mechanism through Metal Solid Foams

Abstract

Solid foams have been intensely studied as promising structured catalytic internals. However, mechanisms governing flow and transport phenomena within the foam structures have not been properly addressed in the literature. The aim of this study was to consider such flow mechanisms based on our experimental results on flow resistance. Two mechanisms were considered: developing laminar flow in a short capillary channel (flow-through model), and flow around an immersed solid body, either a cylinder or sphere (flow-around model). Flow resistance experiments were performed on three aluminum foams of 10, 20, and 40 PPI (pores per inch), using a 57 mm ID test column filled with the foams studied. The foam morphology was examined using microtomography and optical microscopy to derive the geometric parameters applied in the model equations. The flow-through model provided an accuracy of 25% for the experiments. The model channel diameter was the foam cell diameter, and the channel length was the strut thickness. The accuracy of the flow-around model was only slightly worse (35%). It was difficult to establish the geometry of the immersed solid body (sphere or cylinder) because experiment characteristics tended to change from sphere to cylinder with increasing PPI value.

Metal Foams as Novel Catalyst Support in Environmental Processes

“…As can be noticed, for both, the heat ( Figure 2) and the mass (Figure 3), when a given correlation describes quite well the results obtained for one foam, it very often fails for the others [22]. A similar situation was also observed for flow resistance [23,24]. In the literature, many correlations describing the heat (e.g., [15][16][17][18]) and mass transfer coefficient (e.g., [1,[19][20][21]) for solid foams can be found.…”

“…As can be noticed, for both, the heat ( Figure 2) and the mass (Figure 3), when a given correlation describes quite well the results obtained for one foam, it very often fails for the others [22]. A similar situation was also observed for flow resistance [23,24]. Nu/Pr 1/3 (describing the heat transfer) and in equivalent mass transfer term (Sh/Sc 1/3 ), according to the Chilton-Colburn analogy (equation (1)).…”

Catalytic Combustion of Low-Concentration Methane on Structured Catalyst Supports

“…The foam sample (cylinder, 10 mm in diameter and high) was scanned with the voxel size of 10 μm. The image processing was performed using the global thresholding method assisted by iMorph software; the details can be found in our previous works. − The cells, windows, and strut dimensions were determined using optical microscopy methods based on about 100 measurements for each of them.…”

DeNOx Abatement Modelling over Sonically Prepared Copper USY and ZSM5 Structured Catalysts

“…In the literature reports, the short channel structures as well as metallic foams have recently been reported as having a great potential as catalyst supports for gas exhaust abatement [12][13][14][15][16]. In our previous works [12,17,18], we reported the superior activity of ion-exchanged Cu/SSZ-13 and Cu/ZSM-5 zeolite catalysts deposited on kanthal plates and foams.…”

“…The heat and mass transfer characteristics for the stacked wire gauze sheets and metal foam structures were obtained experimentally by using the methodology presented in [13,35]. For the classical ceramic monolith, the literature data were used [7,29].…”