The liquid spreading on porous solids: Dual action of pores

Maiti, Rishi; Arora, Rishabh; Khanna, Rajesh; Nigam, K.D.P.

doi:10.1016/j.ces.2005.05.022

Cited by 13 publications

(19 citation statements)

References 13 publications

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“…Then, bridges are formed between intra and extra particle liquid and facilitate the spreading out of films on the particle by surface tension effect, liquid attracting liquid. These conclusions join those presented by Maiti et al 5 These authors used a tilting perforated plate to represent a porous particle. They highlighted that the liquid drops in contact with ''the pores'' of the particle filled by liquid required a higher gravity force effect (i.e., a higher inclination angle of the plate) to be taken down.…”

Section: Trickle Bed Setupsupporting

confidence: 89%

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Wetting topology in trickle bed reactors

Baussaron¹,

Julcour-Lebigue²,

Wilhelm³

et al. 2007

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com).Local and average partial wetting efficiencies in trickle-beds have been directly measured by image processing and PIV analysis. Two different setups have been implemented: a vertical monolayer of pellets where the wetting structure and stability and also local velocity gradient are characterized by PIV, and a fixed bed to analyze (by photography) the axial evolution of wetting over bed cross section after a transient injection of dye. Porous alumina spheres and different liquids have been used to examine the effect of liquid-solid affinity; two liquid distributors, and bed prewetting were investigated at low liquid superficial velocities (0.5 Â 10 À3 -10 À2 m/s). Contrary to usual techniques (excepting MRI), not only average wetting efficiencies are derived from the colorimetric tracing, but also local features: axial evolution of wetting, size, and locations of dry zones, distributions of wetting efficiency at a particle scale. All those local data are important to improve reactor models assuming uniform pellet wetting. The effect of liquid-solid affinity is predominant in the case of the monolayer of beads, and, contrary to usual assumption, is still significant for the real trickle bed in the low range of wetting efficiency, corresponding to liquid superficial velocity lower than 2 Â 10 À3 m/s.

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Section: Trickle Bed Setupsupporting

confidence: 89%

“…The pores of catalyst also drive the liquid rivulets, which flow from pores to pores. 5 Let us notice however that the ''pores'' of these experiments are holes of several millimeters, very far from the usual size of catalyst pores.…”

Section: Introductionmentioning

confidence: 99%

Wetting topology in trickle bed reactors

Baussaron¹,

Julcour-Lebigue²,

Wilhelm³

et al. 2007

AIChE Journal

View full text Add to dashboard Cite

show abstract

“…They confirmed this effect with a perforated plate modeling a porous substrate and showed that internal wetting improves external wetting by the formation of liquid bridges. The pores of catalyst also drive the liquid rivulets, which flow from pores to pores 5. Let us notice however that the “pores” of these experiments are holes of several millimeters, very far from the usual size of catalyst pores.…”

Section: Introductionmentioning

confidence: 91%

Combination chemotherapy for desmoid tumors

Okuno

Edmonson

2003

Cancer

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Local and average partial wetting efficiencies in trickle‐beds have been directly measured by image processing and PIV analysis. Two different setups have been implemented: a vertical monolayer of pellets where the wetting structure and stability and also local velocity gradient are characterized by PIV, and a fixed bed to analyze (by photography) the axial evolution of wetting over bed cross section after a transient injection of dye. Porous alumina spheres and different liquids have been used to examine the effect of liquid–solid affinity; two liquid distributors, and bed prewetting were investigated at low liquid superficial velocities (0.5 × 10−3–10−2 m/s). Contrary to usual techniques (excepting MRI), not only average wetting efficiencies are derived from the colorimetric tracing, but also local features: axial evolution of wetting, size, and locations of dry zones, distributions of wetting efficiency at a particle scale. All those local data are important to improve reactor models assuming uniform pellet wetting. The effect of liquid–solid affinity is predominant in the case of the monolayer of beads, and, contrary to usual assumption, is still significant for the real trickle bed in the low range of wetting efficiency, corresponding to liquid superficial velocity lower than 2 × 10−3 m/s. © 2007 American Institute of Chemical Engineers AIChE J, 2007

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“…In the recent past, significant efforts have been made to understand the roots of the difference in predictions of these models by studying particle level flow features experimentally as well as numerically (Khanna and Nigam, 2002; Maiti et al, 2004b, 2005a,b). Khanna and Nigam (2002) predicted several features of liquid spreading over porous surface based on thought experiment.…”

Section: Introductionmentioning

confidence: 99%

“…Maiti et al (2004a) used above concept to examine and explain certain anomalous observations in trickle bed reactors operation such as relatively more liquid spreading on porous but less wettable particles in comparison to non‐porous but more wettable particles. They also presented a simple experiment (Maiti et al, 2005a) on a model substrate (in presence of saturated millimetre sized pores) to prove this dual effect of pores in liquid spreading. Recently Maiti et al (2005b, 2006, 2008) observed experimentally the pronounced but different magnitudes of pressure drop hysteresis with porous, semi‐porous and non‐porous alumina extrudates and they proposed a framework of hysteresis based on the concept of dual action of pores by Khanna and Nigam (2002) along with the concept of participating and nonparticipating particle to explain the mysterious hysteresis phenomena in TBR.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of drop spreading over saturated pores

et al. 2010

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Numerical study of the dual effect of pores in liquid spreading over porous surface (flat and spherical) whereby liquid movement is facilitated as well as restricted (visualised by Khanna and Nigam [Khanna and Nigam, Chem. Eng. Sci. 57, 3401-3405 (2002)]) is presented to improve the present understanding of wetting. Using the volume of fluid (VOF) method in a two-dimensional solution domain, the influence of various parameters viz. drop volume, pore density, surface wettability and liquid properties on the liquid spreading over 2D pellets with saturated pores was numerically investigated. Simulation results were found to capture the key features of the liquid spreading over non-porous and porous surfaces qualitatively. The variation of spread factor and the apex height of liquid film with time were in a good qualitative agreement with the concept of dual action of pores. The liquid spreading was observed to have a direct proportionality with the pore density, that is, higher the number of pores, better was the liquid spreading. It was also observed that the influence of the pores on the liquid spreading was reduced with decrease in the surface wettability. It is expected that this numerical analysis of the liquid droplet spreading over saturated porous surface will be useful for better understanding of the physics of drop and pore (saturated) interactions.Uneétude numérique du double effet des pores dans l'épandage de liquide sur une surface poreuse (plate et sphérique) au moyen de laquelle le mouvement du liquide est facilité et restreint (visualisé par Khanna et Nigam, 2002) est présentée pour améliorer la compréhension présente de l'humidification. En utilisant la méthode VOF (volume de fluide) dans un domaine de solution bidimensionnel, l'influence de divers paramètres, a savoir volume des gouttes, densité des pores, mouillabilité de la surface et propriétés des liquides du liquide répandu sur des granulats en 2D avec pores saturés aété analysée de façon numérique. On a découvert que les résultats de simulation ont ciblé les principales caractéristiques de l'épandage du liquide sur des surfaces non poreuses et poreuses de manière qualitative. La variation du facteur d'épandage et la hauteur de l'apex de la pellicule liquide avec le temps constituaient un bon accord qualitatif avec le concept de double action des pores. On a observé que l'épandage du liquide présente une proportionnalité directe avec la densité des pores, c.-à-d. plus il y avait de pores, meilleurétait l'épandage du liquide. On aégalement observé que l'influence des pores sur l'épandage du liquideétait réduite avec la diminution de la mouillabilité de la surface. On s'attendà ce que cette analyse numérique de l'épandage des gouttelettes de liquide sur une surface poreuse saturée permettra de mieux comprendre la physique des interactions entre les gouttes et les pores (saturés).

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The liquid spreading on porous solids: Dual action of pores

Cited by 13 publications

References 13 publications

Wetting topology in trickle bed reactors

Wetting topology in trickle bed reactors

Combination chemotherapy for desmoid tumors

Numerical study of drop spreading over saturated pores

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