Author
J.R.F. Guedes de Carvalho
Other affiliations: University of Porto
Bio: J.R.F. Guedes de Carvalho is an academic researcher from Faculdade de Engenharia da Universidade do Porto. The author has contributed to research in topics: Mass transfer & Packed bed. The author has an hindex of 12, co-authored 22 publications receiving 465 citations. Previous affiliations of J.R.F. Guedes de Carvalho include University of Porto.
Topics: Mass transfer, Packed bed, Bubble, Sherwood number, Two-phase flow
Papers
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TL;DR: In this paper, a photographic study of the wakes of slugs rising in tubes of 19 mm and 52 mm internal diameter is presented, where the dependence of the flow pattern in the wake upon the Reynolds number of the rising slug, R, is established for different slug lengths.
Abstract: A photographic study of the wakes of slugs rising in tubes of 19 mm and 52 mm internal diameter is presented. The dependence of the flow pattern in the wake upon the Reynolds number of the rising slug, R, is established for different slug lengths. Values of R covered in this study are in the range 25 to 1.3 × 104. For low values of R the flow pattern in the wake is laminar and axisymmetric and values of wake length and wake volume could be determined from the photographs: these values were correlated with the other variables in the system by means of dimensional analysis.
146 citations
TL;DR: In this article, the effect of liquid properties on axial dispersion in packed beds was investigated and the experimental data used to test available correlations for predicting DL show that they are inaccurate over considerable ranges of the variables.
Abstract: An experimental study is described on the effect of liquid properties on axial dispersion in packed beds. Working with water between 278 and 373 K, the range 57 600). A representation of PeL vs. Pem reveals the existence of a very flat minimum (typically 102 700, but it increases significantly with a decrease in Sc, for Sc<700. The experimental data used to test available correlations for predicting DL show that they are inaccurate over considerable ranges of the variables.
52 citations
TL;DR: In this paper, the authors measured the transverse and longitudinality of dispersion coefficients for liquid flow through granular packedbed s. The data obtained, together with data from other sources, both for gas and liquid flow, are reported in plots of Pe T vs Pe m and Pe L vs Pe M, in order to stress the influence of Sc on dispersion and elucidate the difference between liquid and gas behaviour.
44 citations
35 citations
TL;DR: In this article, the authors measured the transverse dispersion coefficient of 2-naphthol/water over a range of temperatures between 293K and 373K, which corresponds to a range values of viscosity (μ) between 2.83×10−4 Ns/m2 and 1.01×10 −3 Ns /m2, and molecular diffusion coefficient (Dm) between 1.03× 10−9 m2/s and 5.49× 10 −9 m 2/s.
Abstract: Experimental values of the coefficient of transverse dispersion (DT) were measured with the system 2-naphthol/water, over a range of temperatures between 293K and 373K, which corresponds to a range of values of viscosity (μ) between 2.83×10−4 Ns/m2 and 1.01×10−3 Ns/m2 and of molecular diffusion coefficient (Dm) between 1.03×10−9 m2/s and 5.49×10−9 m2/s. Since the density (ρ) of water is close to 103 kg/m3, the corresponding variation of the Schmidt number (Sc=μ/ρDm) was in the range 1000 – 50. More than 200 experimental values of the transverse dispersion coefficient were obtained using beds of silica sand with average particle sizes (d) of 0.297 and 0.496mm, operated over a range of interstitial liquid velocities (u) between 0.1mm/s and 14mm/s and this gave a variation of the Reynolds number (Re=ρdue/μ) between 0.01 and 3.5.
26 citations
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TL;DR: The use of gas bubbles and slugs in microfiltration and ultra-filtration with flow inside tubes and fibres, across flat sheets and outside fibres is discussed in this article.
477 citations
TL;DR: In this paper, the authors summarized and reviewed a great deal of information from the literature on dispersion in packed beds, and provided empirical correlations for the prediction of the dispersion coefficients (D T and D L) over the entire range of practical values of Sc and Pem.
Abstract: The phenomenon of dispersion (transverse and longitudinal) in packed beds is summarized and reviewed for a great deal of information from the literature. Dispersion plays an important part, for example, in contaminant transport in ground water flows, in miscible displacement of oil and gas and in reactant and product transport in packed bed reactors. There are several variables that must be considered, in the analysis of dispersion in packed beds, like the length of the packed column, viscosity and density of the fluid, ratio of column diameter to particle diameter, ratio of column length to particle diameter, particle size distribution, particle shape, effect of fluid velocity and effect of temperature (or Schmidt number). Empirical correlations are presented for the prediction of the dispersion coefficients (D
T and D
L) over the entire range of practical values of Sc and Pem, and works on transverse and longitudinal dispersion of non-Newtonian fluids in packed beds are also considered.
436 citations
TL;DR: Theoretical and empirical approaches to the fluid dynamic description of liquid fluidized beds are reviewed, together with the relevant experimental evidence as mentioned in this paper, with one section devoted to binary-solid systems, the particles differing in size and/or in density.
281 citations
TL;DR: In this article, a simple general model for the interaction between a particle and the fluid in a fluidized suspension, enables a hydrodynamic criterion for the onset of bubbling in fluidized beds to be formulated in a compact and fully predictive form.
243 citations
TL;DR: In this article, the shape and velocity of the slug, the velocity distribution and the distribution of local wall shear stress were computed and compared favourably with the published experimental findings.
241 citations