摘要:

AbstractPrevious work on delineating flow patterns for the horizontal two‐phase flow of gas and Newtonian liquid is briefly described. One of the flow pattern maps has been slightly adjusted to take account of the evidence from more recent studies. It is shown that physical properties of the system have relatively little influence on flow regime. It is then established that this map is also applicable when the liquid shows shear‐thinning non‐Newtonian prope

ISSN:0008-4034    

DOI:10.1002/cjce.5450620401

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

年代:1984

数据来源: WILEY

摘要:

AbstractSubstantial grid leakage in large industrial fluidized beds is highly undesirable because it can lead, among other things, to grid erosion or plugging. Experiments have been carried out to study grid leakage using a cracking catalyst (arithmetic mean diameter 65 μm) in a 0.6 m diameter column. The flow pattern under the grid was charted with a hot wire anemometer. Micro‐isokinetic probes were developed to study the particle flux returning from the windbox towards the grid. Particles were sucked in isokinetically, recovered in a filter, weighed and analyzed for particle size in a Coulter counter. Upward particle fluxes at the grid were determined by extrapolation of the flux at various distances below the grid. Grid leakage was studied for grids of various geometries which had holes of 1.27 cm diameter. Various measurement methods, a model for re‐entrainment and correlations are g

ISSN:0008-4034    

DOI:10.1002/cjce.5450620402

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

年代:1984

数据来源: WILEY

摘要:

AbstractA new voidage function is defined based on the Blake–Kozeny equation. This voidage function gives better correlations than those heretofore used in describing minimum fluidization characteristics.Due to the inter‐particle cohesive forces, the channelling and bubbling often exist in the fluidization of fine particles. In consideration of the channelling effect, a correlation of the fluidization friction factor is proposed. It is also shown in experiments that the channelling in fine particle systems is reduced when coarser particles are ad

ISSN:0008-4034    

DOI:10.1002/cjce.5450620403

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

年代:1984

数据来源: WILEY

摘要:

AbstractNew experimental work on fluid to particle heat transfer was carried out in a 13.3 cm diameter bed of narrow‐cut and mixed‐sized ferric oxide particles. It was shown that, the channelling effect should be considered for fine particle systems. A correlation including the channelling effect was obtained from the experimental results. The addition of coarser particles into the fine particle systems provides better fluidization behavior and results in an increase in fluid to particle heat transfer coefficient. The most effective content of coarser particles is about 25%, and the optimum particle diameter ratio is about se

ISSN:0008-4034    

DOI:10.1002/cjce.5450620404

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

年代:1984

数据来源: WILEY

摘要:

AbstractHeat transfer coefficients for heating helical coils immersed in a jet‐stirred vessel have been investigated. Geometric factors, such as the tube diameter, the pitch of the helical diameter, the jet nozzle diameter and the turn‐down angle of the jet nozzle, have been studied. Four process liquids of quite different physical properties (water, 70% glycerin, isopropyl alcohol, and KSK oil‐260) have been used as the heating mediums. The correlation developed for these Newtonian liquids is similar to that obtained for vessels with conventional mechanical agitators. The jet power requirement was also obtained from experimental

ISSN:0008-4034    

DOI:10.1002/cjce.5450620405

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

年代:1984

数据来源: WILEY

摘要:

AbstractConvective flow and heat transfer of a Boussinesq fluid contained between two horizontal concentric cylinders is investigated under the effects of two driving mechanisms – an externally‐imposed temperature gradient across the annulus, and a uniform internal heat generation. Numerical results for flow field and temperature distribution are obtained in terms of four dimensionless parameters, namely the radius ratio,R, the Prandtl number, Pr, the Rayleigh number, Ra*, and the ratio,S, between the characteristic temperature induced by internal heating and the applied temperature difference between the boundaries. Depending on the value ofS, the flow pattern is made up of either one or two vortices in each half cavity, and heat is transferred into or out of the cavity through the hot wall. In particular, for a certain value of the applied temperature difference, the hot wall apparently acts as a thermally‐insulated boundary, the internal heat is completely lost through the cold wall, and the fluid undergoes a transition from a bicellular to a unicellular flow r

ISSN:0008-4034    

DOI:10.1002/cjce.5450620406

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

年代:1984

数据来源: WILEY

摘要:

AbstractMass transfer rates at rough surfaces composed of V‐shaped grooves perpendicular to the direction of flow have been measured in a 25 mm square duct by an electrochemical technique. Roughness heights ranged from 50 to 700 μm, at various pitch/height ratios. The Reynolds number was varied from 2000 to 85,000, at Schmidt numbers of 1600 and 3600. Transfer enhancement depended on both size and shape of the roughness elements; rates four times greater than smooth surface values were observ

ISSN:0008-4034    

DOI:10.1002/cjce.5450620407

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

年代:1984

数据来源: WILEY

摘要:

AbstractA small (15 cm square) Davy McKee Combined Mixer Settler has been subjected to hydrodynamic and mass transfer experiments. These included measurements of pumping head, power dissipation, holdup, droplet size and mass transfer efficiency. It was found that the holdup in the dispersed region was in general not uniform, with slight dependence on agitator speed, phase flow rates, etc. The droplet sizes in the impeller region were correlated in terms of agitator speed and system properties. The mass transfer efficiency for the system water/n‐butyric acid/kerosene was affected by agitator speed, overall retention time, and the direction of mass transfer (to or from the dispersed phase). However, it was substantially unaffected by the ratio of phases fe

ISSN:0008-4034    

DOI:10.1002/cjce.5450620408

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

年代:1984

数据来源: WILEY

摘要:

AbstractFoam‐breaking with a rotating disk mechanical foam‐breaker (MFRD) was studied for a foaming system containing a diluted detergent solution in a laboratory sparged agitated vessel. The change of the foam‐breaking capacity of the MFRD by varying the air sparge rate, the working volume and the impeller speed or the disk diameter was measured. Based on these measurements, empirical equations are presented for predicting the critical foam‐breaking regions of the MFRD fitted with the agitated vessel. The operational range where foam‐breaking with the MFRD can be carried out effectively and economically is also

ISSN:0008-4034    

DOI:10.1002/cjce.5450620409

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

年代:1984

数据来源: WILEY

摘要:

AbstractThis paper examines the rate of absorption of molecular oxygen in an aqueous solution of sodium sulphite as a function of temperature over the range of 20–240°C. First, we determined the effect of the various parameters (oxygen partial pressure, sulphite and catalyst concentration, agitation) on the enhancement factor,E.It was observed that an Arrhenius' type relationship could describe the dependence of the physical absorption rate on temperature. According to the degree of agitation, two values for the activation energy: 22.8 and 12.7 kJ · mol−1are obtained. Our results validate the various models formerly proposed only for the range 10–40°C, but show that they cannot be extrapolated above 50°C. The results also show that a simple test at ambient temperature can be used to predict the oxygen transfer capability of a reactor at temperatures up

ISSN:0008-4034    

DOI:10.1002/cjce.5450620410

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

年代:1984

数据来源: WILEY