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Solids Volume Fraction (solid + volume_fraction)
Selected AbstractsTensile Behaviour of Replicated Aluminium Foams,ADVANCED ENGINEERING MATERIALS, Issue 6 2004J.-F. Despois Abstract The replication process is used to produce open-cell 99.99,% pure aluminium foams of controlled pore diameter and solid volume fraction; each parameter is varied respectively from 40 to 400,,m and 10 to 30,vol. pct. The foam tensile behaviour is consistent with the small-strain compressive behaviour and shows a significant dependence on pore size. [source] Measurements by MRI of the settling and packing of solid particles from aqueous suspensionsAICHE JOURNAL, Issue 6 2009Julio Acosta-Cabronero Abstract This study extends the application of existing magnetic resonance imaging methods to measure the settling of solid particles from aqueous suspensions. The acquisition of one-dimensional multiecho projections allowed the direct measurement of initial magnetizations (M0), from which solid volume fractions along the sedimentation column were inferred. For polystyrene beads, it was found that monoexponential curves accurately fitted the transverse relaxation decays. In contrast, for the other four solids investigated (activated carbon, talc, calcium carbonate, and glass beads), the single exponential model did not suffice and additional terms in the fitting function significantly improved the calculation of solid concentrations. Additional information about particle sizes was obtained by comparing volume fractions with the spin,spin relaxation times of the hydrogen protons as a function of the vertical height through the sedimenting suspensions of activated carbon and polystyrene beads. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Effects of Viscous Dissipation on Heat Transfer between an Array of Long Circular Cylinders and Power Law FluidsTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2007R. P. Chhabra Abstract The free surface model has been combined with the equations of motion and of thermal energy to investigate the role of viscous dissipation on heat transfer between banks of long cylinders and power law (shear-thinning and shear-thickening) fluids. The equations of motion cast in the stream function/vorticity formulation have been solved numerically using a second-order accurate finite difference method to obtain extensive information on the behaviour of local and surface-averaged Nusselt numbers over a range of Reynolds numbers 1 , 500, for a wide range of power law indices (0.4 , n , 2.0), Brinkman numbers (0 , Br , 5) and Prandtl numbers (Pr = 1, 1000) at two representative solid volume fractions corresponding to the porosities of e = 0.4 and 0.9. Two different thermal boundary conditions are considered at the cylinder surface: constant temperature (CT) and constant heat flux (CHF). The results presented herein provide a fundamental knowledge about the influence of viscous dissipation on the heat transfer characteristics. The results reported herein further show that the effect of Brinkman number on heat transfer is strongly conditioned by the thermal boundary condition, Prandtl number and the power law index. On a combiné le modèle de surface libre aux équations de mouvement et de transfert de chaleur afin d'étudier le rôle de la dissipation visqueuse sur le transfert de chaleur entre des rangées de cylindres longs pour des fluides de loi de puissance (rhéofluidifiants et rhéoépaississants). Les équations de mouvement formulées en fonction de courant/vorticité ont été résolues numériquement à l'aide d'une méthode de différences finies du second ordre, afin d'obtenir des informations détaillées sur le comportement des nombres de Nusselt locaux et moyennés en surface pour une gamme de nombres de Reynolds compris entre 1 et 500, une large gamme d'indices de loi de puissance (0,4 , n , 2,0), de nombres de Brinkman (0 , Br , 5) et de nombres de Prandtl (Pr = 1,1000) à deux fractions de volume de solides correspondant à une porosité de e = 0,4 et 0,9. Deux conditions aux limites thermiques ont été considérées à la surface du cylindre: la température constante (CT) et le flux de chaleur constant (CHF). Les résultats présentés permettent de rendre compte de l'influence de la dissipation visqueuse sur les caractéristiques du transfert de chaleur et l'effet du nombre de Brinkman sur le transfert de chaleur qui est fortement influencé par la condition aux limites thermique, le nombre de Prandtl et l'indice de loi de puissance. [source] Penetration of Shear Flow Into an Array of Rods Aligned With the FlowTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2004Anthony M. J. Davis Abstract Shear flow over a square array of widely-spaced rods aligned with the flow is investigated using singularity methods to solve Stokes equation. The flow field is determined for various arrays occupying a fraction of a Couette channel, for solid volume fractions from 0.001 to 0.1. Flow penetration into an array is quantified by the slip velocity at the array edge. This velocity is much greater than when the flow is across the array but still less than the value predicted by the use of Brinkman's equation. À l'aide de méthodes de singularité destinées à résoudre l'équation de Stokes, on a étudié l'écoulement de cisaillement sur un vaste arrangement carré de tiges largement espacées alignées à l'écoulement. Le champ d'écoulement est déterminé pour divers arrangements occupant partiellement un canal de Couette, pour des fractions volumiques de solides comprises entre 0,001 et 0,1. La pénétration de l'écoulement dans le dispositif est quantifiée par la « vitesse de glissement au bord du dispositif. Cette vitesse est beaucoup plus grande que dans le cas où l'écoulement est transversal par rapport au dispositif mais est encore inférieure à la valeur prédite au moyen de l'équation de Brinkman. [source] Estimation of the hindered settling function R(,) from batch-settling testsAICHE JOURNAL, Issue 4 2005Daniel R. Lester Abstract The hindered settling function R(,) is a material function that quantifies the interphase drag of colloidal suspensions for all solids volume fractions ,. A method is presented to estimate R(,) from batch-settling tests for solids volume fractions between the initial solids volume fraction, ,0, and the solids volume fraction at which the suspension forms a continuously networked structure, ,g, known as the gel point. The method is based on an analytic solution of the associated inverse problem. Techniques are presented to address initialization mechanics observed in such tests as well as experimental noise and discrete data. Analysis of synthetic and experimental data suggests that accurate estimates of R(,) are possible in most cases. These results provide scope for characterization of suspension dewaterability from batch-settling tests alone. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source] Systematic Approach for Dispersion of Silicon Nitride Powder in Organic Media: II, Dispersion of the PowderJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2000Liwu Wang A novel dispersant,O-(2-aminopropyl)-O,-(2-methoxyethyl)-polypropylene glycol (AMPG),was developed to disperse submicrometer-sized Si3N4 powder in nonaqueous media, based on the surface chemistry of the powder. The dispersing phenomena and mechanisms have been studied systematically, both in model systems (using atomic force microscopy and ellipsometry) and in powder systems (using rheological behavior and adsorption isotherms). The results from the model systems correlated well with those from wet powder systems. It is demonstrated that highly concentrated (with a solids volume fraction of >0.50) and colloidally stable nonaqueous Si3N4 suspensions can be realized using AMPG. [source] Effects of Ammonium Chloride on the Rheological Properties and Sedimentation Behavior of Aqueous Silica SuspensionsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2000J. Jiyou Guo The influence of ammonium chloride (NH4Cl) on the rheological properties and sedimentation behavior of aqueous silica (SiO2) suspensions of varying solids volume fraction (,s) was studied. SiO2 suspensions with low NH4Cl concentration (,0.05M, pH 5.2) exhibited Newtonian behavior and a constant settling velocity (U). The volume fraction dependence was well described by the Richardson,Zaki form, U=U0(1 ,,s)n, where n= 4.63 and U0= 1.0419 × 10,5 cm/s. At higher NH4Cl concentrations (0.07,2.0M, pH 5.2), suspensions exhibited shear thinning and more complicated sedimentation behavior due to their aggregated nature. For all suspensions studied, however, the apparent suspension viscosity, characteristic cluster size, and initial settling velocity were greatest at ,0.5M NH4Cl and exhibited a similar dependence on salt concentration. Above 0.5M NH4Cl, considerable restabilization was observed. This behavior cannot be explained by traditional DLVO theory. [source] Filtration of Colloidal Suspensions , MRI Investigation and Numerical SimulationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2006A. Erk Abstract The principle mechanisms of solid-liquid separation processes are sedimentation and filtration, both including the formation and compression of a liquid-saturated bulk. The compressive properties of the bulk determine the operating parameters of solid-liquid separation devices and the achievable separation results. Information about the solids volume fraction of the bulk is essential for a better understanding of the physical mechanisms and precise modeling. A numerical model for the calculation of the local solids volume fraction during formation and compression of filter cakes and sediments was developed. The calculated results are compared with experimental NMR data. [source] Estimation of the hindered settling function R(,) from batch-settling testsAICHE JOURNAL, Issue 4 2005Daniel R. Lester Abstract The hindered settling function R(,) is a material function that quantifies the interphase drag of colloidal suspensions for all solids volume fractions ,. A method is presented to estimate R(,) from batch-settling tests for solids volume fractions between the initial solids volume fraction, ,0, and the solids volume fraction at which the suspension forms a continuously networked structure, ,g, known as the gel point. The method is based on an analytic solution of the associated inverse problem. Techniques are presented to address initialization mechanics observed in such tests as well as experimental noise and discrete data. Analysis of synthetic and experimental data suggests that accurate estimates of R(,) are possible in most cases. These results provide scope for characterization of suspension dewaterability from batch-settling tests alone. © 2005 American Institute of Chemical Engineers AIChE J, 2005 [source] | |||||||||||||