摘要:

AbstractThe (κ‐ϵ) turbulence closure model has become a widely used means of predicting turbulent fluid flows. In this paper the turbulent radial jet, the round jet and the plane jet are calculated in their similarity regions using various versions of the (κ‐ϵ) model to determine which is the most satisfactory for both plane and axisymmetric flows. The most general predictions were obtained using a model which contained additional terms to account for the effect of irrotational strains on the production of turbulence energy. Additionally, detailed mean velocity profiles and turbulence kinetic energy profiles of the radial jet are compared to the available experiment

ISSN:0008-4034    

DOI:10.1002/cjce.5450630201

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

年代:1985

数据来源: WILEY

摘要:

AbstractAn experimental study was conducted to determine the effects of nozzle orifice size and operating parameters on the cone angle of a liquid fuel spray injected into a gaseous environment. High fuel pressures in the range 55 to 130 MPa and background gas density ranging from atmospheric to 40 kg/m3were used in the study. The results show the spray cone angle to depend on the orifice dimensions as well as on the operating conditions such as the injection velocity and the background gas density. A correlation is derived to predict spray cone angles in terms of Reynolds and Weber numbers. The predicted results are shown to agree well with the experimental findings of other investigators.

ISSN:0008-4034    

DOI:10.1002/cjce.5450630202

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

年代:1985

数据来源: WILEY

摘要:

AbstractAn axisymmetric model of flow in the annulus of a spouted bed of coarse particles which takes into account non‐Darcy flow and utilizes a new and general axial pressure boundary condition at the spout‐annulus interface is presented. The pressure boundary condition and the annulus pressure distribution are experimentally verified and the model used to calculate the residence time distribution and the flowrate at the top of the annulus. In addition, the average axial velocity profile in the annulus is calculated and compared with predictions of several one‐dimensional flow m

ISSN:0008-4034    

DOI:10.1002/cjce.5450630203

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

年代:1985

数据来源: WILEY

摘要:

AbstractThis paper presents some new data for the liquid phase axial dispersion coefficient in a bubble column with highly viscous non‐Newtonian liquids (μL>0.03 Pa · s). The data were obtained in a 0.15 m diameter column operating in the slug flow regime, and the dispersion measurements were conducted using heat aas a tracer. The experimental results show that the dispersion coefficients increase with both gas and liquid velocities and quantitatively they are about three times higher than those obtained for the air‐water system. The results are explained based on a known hydrodynamic model of vertical gas‐liquid sl

ISSN:0008-4034    

DOI:10.1002/cjce.5450630204

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe authors recently proposed (André et al., 1981) a new method of measuring the overall volumetric mass transfer coefficient (KLaL) in gas‐liquid‐solid contactors of the bubble‐column type. The present paper deals with improved implementation of this method. The previous work showed that prior knowledge of the extent of backmixing in the gas phase was required in order to obtain reliable estimates ofKLaL. It is shown here that parameter fitting in the frequency domain, using the Fourier transform of the response curves, may be used to estimate bothKLaLand the extent of backmixing in the gas phase simultaneously. The main features of this particular approach are described in detail and are discussed in the light of experimental data obtained in two bench‐scale contactors (a bubble column and the novel inverted conical bottom contactor). In addition, the effect of contactor geometry and paper pulp addition onKLaLalso is presented. It is shown that both the conventional bubble column and the novel contactor yield comparable gas‐liquid mass tran

ISSN:0008-4034    

DOI:10.1002/cjce.5450630205

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

年代:1985

数据来源: WILEY

摘要:

AbstractA precise model for predicting liquid‐liquid extraction column efficiency based upon assumed hydrodynamic, axial mixing and mass transfer behaviour has been formulated and solved numerically.The complex nature of the dispersed phase can be better described by drop‐size‐dependent residence time distribution (RTD). Both the variation of axial velocities due to drops of different sizes, i.e. forward mixing, and the axial dispersion for the drops of the same size have been considered in this model.The computed results reveal that the effects of both varying velocities and dispersion of drops on extraction efficiency are appreciable and cannot be neglected, and the efficiency may be overestimated if only a forward mixing model is adopted. The comparison of the experimental values ofNODPwith those predicted shows that the mass transfer data obtained in RDC agree well with the values predicted by the present model for the case of solute transfer inc→ddirection, and are slightly higher than the predicted ones for the transfer ind→c

ISSN:0008-4034    

DOI:10.1002/cjce.5450630206

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

年代:1985

数据来源: WILEY

摘要:

AbstractCoal pyrolysis has been studied to determine conditions for maximum liquid yields from some Western Canadian coals. Gas, tar and char yields were determined for four coals in a 12.8 cm dia. reactor. A characteristic temperature for maximum tar yield existed for each coal at a fixed feed rate and particle size. A steady increase in tar yield was found as the average coal particle size was reduced from 2.28 to 0.65 mm. Composition of gas, and ultimate analyses of tar and char are presented as a function of operating temperature. A simple first‐order devolatilization model adequately describes the effects of coal feed rate, reaction time, and temperature on the yield of volatiles, but is insufficient to describe particle size effect

ISSN:0008-4034    

DOI:10.1002/cjce.5450630207

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe fused salt electrolysis of AlCl3dissolved in LiCl‐NaCl melts at 700°C was studied using bench scale cells employing graphite electrodes. The effects of AlCl3concentration, forced convection, interelectrode spacing, and current density on the voltage, current, and energy efficiencies of the process were investigated. At a practical cell voltage of 3.05 V and current density of 15 kA·m−2the electrical energy consumption per kg of aluminum produced by the AlCl3process was about 32 MJ, compared with a typical value of 52 MJ·kg−1for the Hall‐Héroult e

ISSN:0008-4034    

DOI:10.1002/cjce.5450630208

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe breakup of emulsion jets ejected downward into air from a nozzle has been investigated experimentally, and the breakup length of jets and the drop size for kerosene‐water emulsions have been measured. The concentration of the dispersed phase was less than 50 wt%, so all experimental emulsions exhibited Newtonian flow. Photographic observation indicated that the emulsion jet resembled the jet of normal homogeneous liquids. The breakup length of the jet and the drop size from the jet are in good agreement with predictions from stability analysis for normal liquid

ISSN:0008-4034    

DOI:10.1002/cjce.5450630209

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

年代:1985

数据来源: WILEY

摘要:

AbstractThe possibility of utilizing peat as adsorbent for removal of the pesticide 2,4‐D from contaminated wastewaters has been evaluated in this investigation.Batch tests were conducted at different conditions of initial solute concentration, pH, particle size of adsorbent, temperature and ratios of weight of adsorbent to solution volume, in order to determine the optimum range of these variables for the adsorption operation. Removal ratios for the 2,4‐D of the order of 90% were obtained under optimum conditions. The adsorption of 2,4‐D in peat is described adequately by the Freundlich isotherm.Continuous tests, utilizing adsorption columns, were then conducted in order to determine the design parameters for a proposed treatment plant. The column tests were adequately correlated by the Bohart‐Adams e

ISSN:0008-4034    

DOI:10.1002/cjce.5450630210

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

年代:1985

数据来源: WILEY