摘要:

AbstractAn experimental study was conducted to examine solids distribution in branches of a linear manifold having a horizontal approach. The manifold was designed to maintain approximately a constant slurry velocity upstream of each branch. Solids concentration in the branches was measured for various manifold orientations (upwards, side and downwards) and upstream conditions.Semi‐empirical correlations for the three orientations were developed to predict a branch concentration ratio. This ratio was dependent upon the branch flow ratio, the particle inertia parameter and the vertical solids concentration profile upstream of the branch. The agreement between the experimental and the predicted branch concentration ratio was fairly goo

ISSN:0008-4034    

DOI:10.1002/cjce.5450700102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractExperimental work was carried out to investigate the rheological properties of bitumen in water emulsions containing solids of different shape and size. The bitumen volumetric concentration was varied up to 60%, solids free basis, and the solids volume fraction (total volume basis) was varied up to 0.2. Irregular‐shaped silica sand (average diameter: 9 and 33 μm) and smooth spherical glass beads (average diameter: 27 and 44 μm) were used as the added solids.In the low shear stress range, shear thinning behavior was observed for bitumen in water emulsions. At high shear stress, the viscosity of the emulsions became fairly independent of the shear stress. The addition of solids to the bitumen emulsions increased the mixture viscosity. The addition of irregular‐shaped silica sand gave a higher viscosity than a similar addition of the spherical glass beads. The viscosity of the emulsion/solids mixtures was influenced by the solids size as well; the smaller size particles gave a higher viscosity.The addition of solids to the bitumen emulsions also induced shear thickening (dilatancy) behavior at high solids volume fraction. The degree of the shear thickening increased with the oil concentr

ISSN:0008-4034    

DOI:10.1002/cjce.5450700103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA Theological characterization of coal/water suspensions has been carried out under continuous and oscillatory flow conditions. Shear stress ‐ shear rate data were correlated with the Shangraw‐Grim‐Mattocks (SGM) equation. The analysis of the SGM parameters indicated that a limiting concentration ϕ0exists above which the suspensions exhibit plastic behavior and suggested that a strong particle aggregation still occurs at high rates of shear. Oscillatory flow tests revealed marked non‐linear viscoelastic properties and analogies were found between the continuous and oscillatory flow behaviors of the coal/water suspensions, particularly under limiting flow co

ISSN:0008-4034    

DOI:10.1002/cjce.5450700104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe void‐size distribution in a random packed assembly of disks is expressed here as the distribution of the probabilities of finding circular voids of given sizes. A theoretical void‐size distribution is derived and compared with the distribution obtained through computer simulation. The two‐dimensional case discussed in this paper is applicable to the study of the kinetics of fines transfer and the characterization of the coating layer structure in powder coating sy

ISSN:0008-4034    

DOI:10.1002/cjce.5450700105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractAir‐holdup and heat transfer coefficient data are reported for the air‐water and air‐water‐sand system as a function of air velocity in the temperature range 297‐343 K as measured in a 0.305 m diameter bubble column operating in semi‐batch mode and equipped with either a five‐ or seven‐tube bundle. A 65 μm average size sand powder is used at concentrations of 5 and 10 mass percent in the slurry. Available correlations of gas holdup and heat transfer coefficients are examined on the basis of these data. These are found inappropriate and inadequate for representing these experimental data. Gas holdup data are well represented by an approach based on Nicklin's (1962) work, and heat transfer data are adequately represented by a simple semi‐empirical expression. Accurate experimental data on additional systems are needed to develop a reliable heat transfer theory particularly for process representation at temperatures h

ISSN:0008-4034    

DOI:10.1002/cjce.5450700106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA mode based on an additive mechanism of heat transfer is proposed for forced convection subcooled boiling of binary mixtures. The contributing modes of heat transfer are: (i) the heat transferred as latent heat by the rising bubbles, (ii) the heat transferred as the heat contained in the superheated thermal layer that is removed from the surface in the wake of the rising bubbles and (iii) the single phase forced convection heat transfer from the heating surface not influenced by the bubbles. Experimental data from the literature on binary systems show good agreement with the model, validating the postulated mechanism.

ISSN:0008-4034    

DOI:10.1002/cjce.5450700107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe earlier work of Calderbank and Moo‐Young (1961) dealing with the liquid‐phase mass transfer coefficient in gas‐liquid dispersions is examined. Their well‐known empirical correlations for small and large bubbles which are free to move under gravity are theoretically derived. The analyses are based on the approach for natural convection mass transfer, and include the case where the fluid is non‐Newtonian. The predictions of the models are compared with reported experimental data and cor

ISSN:0008-4034    

DOI:10.1002/cjce.5450700108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe understanding of the heat and mass transfer phenomena between hot bubbles and a liquid is particularly relevant to the design of direct contact heating and evaporation systems such as submerged combustion equipment. In this process, exhaust gas from a burner is dispersed in a liquid to be heated or evaporated. Various models for the prediction of the temperature and vapor content of the bubbles as a function of their residence time in the liquid are presented. Based on the experimental measurements of the bubble size and of the heating time and evaporation rate in an actual submerged combustion system, models using spherical, ellipsoidal and spherical‐cap bubbles, with or without internal circulation, are discussed and assessed. It is found experimentally that the bubbles are of a spherical cap shape. Bubble equivalent diameters between 15 and 25 mm and bubble velocities between 0.4 and 1.2 m/s are observed. The proposed models are used to compute the heating time and evaporation rate of the bath during a submerged combustion operation; the predictions are then compared to the experimental values. The rigid spherical cap bubble model is found to predict satisfactorily the heat and mass exchanges between the bubbles and the liqui

ISSN:0008-4034    

DOI:10.1002/cjce.5450700109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSpherical bulb fibre optic probes, developed and applied for bubble characterization in a bubble column and a slurry bubble column at high temperature, were investigated. The principle of operation of these new optical fibre probes is based on the difference in refractive indices between the gas and the liquid phases. The interaction between the gas bubbles and the fibre optic probes in a bubble column was studied using photographic techniques. The first objective of these experiments was to study the response of the sensors upon contact with gas bubbles of various sizes. The second objective of this study was to establish, under controlled situations, the optical probe bubble detection performance and ability for local quantitative measurements of the bubble rise velocity and the gas hold‐u

ISSN:0008-4034    

DOI:10.1002/cjce.5450700110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe axial mixing and countercurrent mass transfer characteristics of a 5 cm diameter extraction column agitated by vibrating perforated Teflon plates have been investigated. The dispersed phase was an organic liquid (usually kerosene) and the continuous phase was water. Axial mixing was measured in both phases using pulse tracer techniques; in the continuous phase the axial mixing was estimated to have a significant effect on mass transfer, but axial mixing in the dispersed phase had a negligible effect. Mass transfer was measured for several different solutes;n‐butyric acid, benzoic acid and phenol. The overall heights of a transfer unit (cont. phase) were in the order of 10‐20 cm for the organic‐acids but higher for transfer of phenol from very dilute solutions. The characteristics of the vibrating plate column have been compared with those of other types of extractor and suggestions are made for further develo

ISSN:0008-4034    

DOI:10.1002/cjce.5450700111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY