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Sakae Yagi

Bio: Sakae Yagi is an academic researcher from University of Tokyo. The author has contributed to research in topics: Fluidized bed & Packed bed. The author has an hindex of 11, co-authored 31 publications receiving 1415 citations.

Papers
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TL;DR: In this paper, the authors applied both their own assumptions and the mechanism of lateral mixing proposed by Ranz (20) to obtain theoretical formulas for effective thermal conductivities in packed beds.
Abstract: Applying both their own assumptions and the mechanism of lateral mixing proposed by Ranz (20), the authors obtained theoretical formulas for effective thermal conductivities ke in packed beds. Previously reported experimental data were analyzed with these equations, and the usable data for predicition of ke were shown. In order to see the influence of both packing characteristics and temperature on the effective thermal conductivities, experimental data were obtained with air for beds with various kinds of packing, i.e., iron spheres, porcelain packings, cement clinker, insulating fire brick, and Raschig rings. Correlation of these data with Equation (15) showed that this equation adequately expressed the heat transfer mechanisms in packed beds with motionless gases, especially at hight temperatures.

630 citations

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TL;DR: In this paper, the authors obtained the coefficients of heat transfer on the inner tube surface, as well as the mean effective thermal conductivities of bed, from studies of annular packed beds wherein the heat flows purely radially.
Abstract: From studies of annular packed beds wherein the heat flows purely radially, the authors obtained the coefficients of heat transfer on the inner tube surface, as well as the mean effective thermal conductivities of bed. The inner and outer diameters of the annular packed bed were 22 and 70 mm. respectively, and the packings shown in Table 1 were used. The wall film coefficients obtained with air flowing axially through the bed were correlated for NReM < 600 by means of Equation (14). The coefficients of heat transfer for cylindrical packed beds reported previously by other observers were correlated also by Equation (14), with 0.054 used for values of αω in the range NReM < 2,000. Consideration of Equation (14) in terms of a theoretical model of heat transfer showed that it was reasonable to apply it for the prediction of wall film coefficient, especially for low Reynolds numbers.

212 citations

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TL;DR: In this article, the dissolution rate of the coated material on the inner wall of the packed tube to the water stream was measured, and wall mass transfer coefficients were analyzed, and it was found that a close similarity exists between the JH and JD factor for the wall coefficients in the turbulent-flow region.
Abstract: Experiments of heat and mass transfer from the tube wall to the fluids flowing through the packed beds were carried out separately. In heat transfer air was used as the fluid, and several kinds of solid particles with low and high thermal conductivities were investigated to determine effective thermal conductivities and wall heat transfer coefficients. In mass transfer the dissolution rate of the coated material on the inner wall of the packed tube to the water stream was measured, and wall mass transfer coefficients were analyzed. It was found that a close similarity exists between the JH and JD factor for the wall coefficients in the turbulent-flow region.

166 citations

Journal ArticleDOI
TL;DR: In this article, the distribution of residence times of solid particles is examined in fluidized beds at steady state with continuous feed and discharge of solids, both for beds consisting of a single particle size and for beds with a wide spectrum of particle sizes, and the mean age of particles of a given size is the same in both overflow and carryover streams.

84 citations


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Book
01 Jan 1984
TL;DR: In this paper, the authors describe a transition from Laminar boundary layer flow to Turbulent Boundary Layer flow with change of phase Mass Transfer Convection in Porous Media.
Abstract: Fundamental Principles Laminar Boundary Layer Flow Laminar Duct Flow External Natural Convection Internal Natural Convection Transition to Turbulence Turbulent Boundary Layer Flow Turbulent Duct Flow Free Turbulent Flows Convection with Change of Phase Mass Transfer Convection in Porous Media.

4,067 citations

Journal ArticleDOI
TL;DR: In this paper, the problem of determining the effective thermal conductivity of a two-phase system, given the conductivities and volume fractions of the components, is examined, and an equation based on a three-element resistor model is proposed.
Abstract: The problem of determining the effective thermal conductivity of a two‐phase system, given the conductivities and volume fractions of the components, is examined. Equations are described which have been proposed as solutions to this problem, including those of Maxwell, de Vries, and Kunii and Smith, the weighted geometric mean equation, and an equation based on a three‐element resistor model found applicable to the analogous electrical conductivity problem. Experimental results are presented for five unconsolidated samples: three quartz sand packs, a glass bead pack, and a lead shot pack. The method of conductivity measurement using the transient line heat source (thermal conductivity probe) is described. Data are reported showing the variation of effective thermal conductivity with porosity, solid particle conductivity, saturating fluid conductivity, and the pressure of the saturating gas. From considerations based on the kinetic theory of gases, it is shown that the characteristic dimension of the pore ...

818 citations

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TL;DR: In this article, a regression analysis was applied to the nearly 5000 existing experimental data points for natural convection boiling heat transfer, which can best be represented by subdividing the substances into four groups (water, hydrocarbons, cryogenic fluids and refrigerants) and employing a different set of dimensionless numbers for each group of substances.

710 citations

Journal ArticleDOI
TL;DR: The thermal dispersion conductivity tensor for convection in a porous medium is derived based on the method of volume averaging of the velocity and temperature deviations in the pores.

619 citations

Journal ArticleDOI
TL;DR: In this paper, a numerical simulation of forced convective incompressible flow through porous media, and the associated transport processes was employed, and a full general model for the momentum equation was employed.

605 citations