Determination of porosity and flow distribution in packed beds by magnetic resonance imaging

Nguyen, Ngoc Luan; Buren, V. van; Reimert, R.; Garnier, A. von

doi:10.1016/j.mri.2004.11.061

Cited by 12 publications

(4 citation statements)

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“…Besides X-ray tomography, magnetic resonance imaging may be used as well to investigate local structures within packedbeds. [130][131][132][133][134] Again, a proper image analyzing procedure is required. [131] Results collected from the literature Regarding the obtained radial porosity data, some specific properties are generally accepted, including [20] :…”

Section: Methodsmentioning

confidence: 99%

“…F I G U R E 4 Gathered experimental literature data of radial porosity distributions ϵ(r) obtained by using various experimental methods and packing procedures and containing spheres of different materials enclosed by a cylindrical confining wall [10,49,91,[104][105][106][107]109,116,119,122,126,127,[133][134][135][136][137][138][139][140] Schneider and Rippin [102] evaluated the radial locations of the minima and maxima of their own data and those from Benenati and Brosilow [105] and Goodling et al [107] depending on λ. It was found that the locations of the extrema are independent of λ in the tested range (2.5-15), so that the maxima occur at 1.00, 1.86, 2.75, 3.63, and 4.50 sphere diameters from the tube wall.…”

Section: Methodsmentioning

confidence: 99%

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Review on the structure of random packed‐beds

Seckendorff

Hinrichsen

2021

Can J Chem Eng

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Independent from their intended purpose, the understanding of structural characteristics of random packings of particles having defined shapes is important to understand and optimize fluid dynamic behaviour, heat, and mass transfer. The packing structure can be described by the coordination number, local porosity profiles, the average porosity, and pore characteristics, which are influenced by the wall and thickness effect; the material, shape, and size distribution of the packing particles; the packing and compaction mode; and the shape and material of the packing's containing walls. Therefore, existing knowledge on the structure of randomly packed mono-sized particles is reviewed to provide an updated selection of relevant parameters and their derived correlations obtained by experimental, numerical, and analytical means.packed-bed reactor, porosity, random particle packings, review, structure | INTRODUCTIONRandom packings of particles having defined shapes are deployed in all kinds of industrial applications and come in all orders of magnitude. The most prominent examples comprise micro-sized particle beds as commonly used in chromatography packed columns, [1][2][3] packed-bed reactors filled with catalytic shaped bodies having millimetre size, [4,5] packed columns used in separation processes such as distillation incorporating particles in the lower centimetre range, [6,7] and the pebble-bed reactor, which is a gas-cooled nuclear reactor, moderated by a packing of graphite spheres. [8][9][10] In addition to those, numerous less-known applications of packed-beds exist, ranging from powder-bed 3D printers, [11] solar-energy storage systems, [12] earth science, [13] civil engineering, [14,15] and pharmaceutical processing, [16] to the pyrolysis of pelletized wood fuels, [17] to name but a few.Irrespective of its intended purpose, the extent of a packed-bed is limited by a confining wall of commonly cylindrical shape, though flat plates and other container geometries are possible. Despite its generally random nature, close to this confinement the particles' placement is naturally forced to align with the wall's geometry. This imposed order reaches a couple of particle diameters into the packing and is usually named the wall effect. Its influence on the overall packed-bed characteristics decreases with increasing tube-to-particle diameter ratio λ = D d p . While most applications operate in an only sparsely affected λ-range, this effect becomes dominant, for instance, in catalytic multitubular reactors, typically performing at λ = 4-7 [18] or a single-pellet-string reactor with a λ < 2. [19] Moreover, some packed-bed utilizations, especially chromatography columns, have very delicate requirements regarding bed homogeneity and its derived characteristics.Abbreviations: DEM, discrete element method; Erfc, error function; J 0 , Bessel function of first kind and zero order; MRJ, maximally random jammed; RCP, random close packing; RLP, random loose packing.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Review on the structure of random packed‐beds

Seckendorff

Hinrichsen

2021

Can J Chem Eng

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“…In other words, the increase in expression and the oxidative products from tissue damage and inflammation led to a drastic decrease in the activation threshold, thereby increasing sensitivity to noxious stimuli (via peripheral sensitization) (Hucho and Levine, 2007). Second, translocation of functional TRP channels from the cytoplasm to the plasma membrane is induced following the activation of second-messenger pathways and subsequent post-translational modification (e.g., channel phosphorylation or glycosylation) (Morenilla-Palao et al, 2004;Nguyen et al, 2005;Zhang et al, 2005). Third, channel phosphorylation as a disinhibition mechanism with inflammatory mediators might cause channel structure alteration and functionally enhance the channel sensitivity (Dai et al, 2007).…”

Section: Trp Channels In Inflammatory Pain Conditionsmentioning

confidence: 99%

Resolvins: Potent Pain Inhibiting Lipid Mediators via Transient Receptor Potential Regulation

Roh

Park

et al. 2020

Front. Cell Dev. Biol.

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Chronic pain is a serious condition that occurs in the peripheral nervous system (PNS) and the central nervous system (CNS). It is caused by inflammation or nerve damage that induces the release of inflammatory mediators from immune cells and/or protein kinase activation in neuronal cells. Both nervous systems are closely linked; therefore, inflammation or nerve damage in the PNS can affect the CNS (central sensitization). In this process, nociceptive transient receptor potential (TRP) channel activation and expression are increased. As a result, nociceptive neurons are activated, and pain signals to the brain are amplified and prolonged. In other words, suppressing the onset of pain signals in the PNS can suppress pain signals to the CNS. Resolvins, endogenous lipid mediators generated during the resolution phase of acute inflammation, inhibit nociceptive TRP ion channels and alleviate chronic pain. This paper summarizes the effect of resolvins in chronic pain control and discusses future scientific perspectives. Further study on the effect of resolvins on neuropathic pain will expand the scope of pain research.

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“…Roblee et al, Benenati et al, Govindarao, et al, Latham et al, Caulkin et al, du Toit, True et al, and Mueller − have studied the void fraction in packed beds. Gotz et al, Poux et al, Zhiyao et al, Farber et al, Forsmo and Vuori, Nguyen et al, and Pahk and Klinzing measured the voidage in packed beds.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Voidage of Sinter Ores in the Tubes

Zhang

Cai

Dong

et al. 2012

Ind. Eng. Chem. Res.

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An industrial vertical tank (cost $200,000) was produced to recover the heat of sinter ores in our laboratory, the voidage along the height direction needs to be studied in order to determine the best height of sintering layer in it. In this paper, the bulk bed voidage of sinter ores in cylindrical polyvinylchloride tube (PVC-U) was measured by the cross-section image analysis method. The large-diameter tube was used to minimize the wall effects so that we could measure the bulk bed voidage in the center of the tube. The results show that the new method is useful, the voidage increases at lower height and fluctuates slightly between 0.36 and 0.43 in a stable stage, the voidage increases as particle size increases, decreases as the shape factor increases, and increases as the tube to particle diameter ratios decreases. These provide significant voidage data for the study of a vertical tank.

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Determination of porosity and flow distribution in packed beds by magnetic resonance imaging

Cited by 12 publications

References 1 publication

Review on the structure of random packed‐beds

Review on the structure of random packed‐beds

Resolvins: Potent Pain Inhibiting Lipid Mediators via Transient Receptor Potential Regulation

Measurement of Voidage of Sinter Ores in the Tubes

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