摘要:

AbstractWith simple hydrodynamic concepts, a physical model is developed to describe the flow at the wall close to the impeller blade. The parameters of this model were evaluated from the large amount of data on power consumption and checked with some independent data on velocity profiles. Together with the physical insight provided by the model, it helped to obtain general relationships for power and heat transfer coefficients. Equations for the latter were developed using Lévêque's approximation. Agreement between the predicted results and the literature data of several independent studies was rather good. A method to analyze mixing or blending results is also suggeste

ISSN:0001-1541    

DOI:10.1002/aic.690290202

出版商:American Institute of Chemical Engineers    

年代:1983

数据来源: WILEY

摘要:

AbstractThe dynamic behavior of a pilot‐plant grinding circuit was modelled by relating three output variables that were representative of the conditions within the mill and the classifier to three input variables, namely feed rates of the solids, mill water, and sump water.A multivariable controller was designed, by the use of Inverse Nyquist Array techniques, for feedback control of the outputs by the inputs, and applied to the plant by a process‐control computer with the use of direct digital cont

ISSN:0001-1541    

DOI:10.1002/aic.690290203

出版商:American Institute of Chemical Engineers    

年代:1983

数据来源: WILEY

摘要:

AbstractBased on the drag force of two spheres in contact and the probability density of size ratios of particles which constitute an aggregate particle, the population balance equation describing the change of the particle‐size distribution due to the disruption of aggregate particles is derived and the numerical solutions of this equation are obtained.Experiments were carried out with fly ash particles dispersed in air stream through an orifice at various flow rates. The measured size distributions can be represented by the numerical solutions of the population balance equatio

ISSN:0001-1541    

DOI:10.1002/aic.690290204

出版商:American Institute of Chemical Engineers    

年代:1983

数据来源: WILEY

摘要:

AbstractThe incubation period preceding “rollover” within a stratified LNG tank involves intensive heat and mass transfers between layers. Numerical integration of equations describing these processes leads to predicted time‐history and boil‐off characteristics which are in excellent agreement with Sarsten's (1972) documentation of the LaSpezia rollover i

ISSN:0001-1541    

DOI:10.1002/aic.690290205

出版商:American Institute of Chemical Engineers    

年代:1983

数据来源: WILEY

摘要:

AbstractThe basic characteristics of a transferred arc argon plasma were determined using a cathode assembly suitable for transferring the electric arc to a molten metal bath or to a cooled anode. They indicated that the sustained voltage depended strongly on the arc length and much less on current. The inlet gas velocity past the cathode tip was determined to be an important operating parameter, rather than the volumetric gas flowrate.The measurement of the axial and radial profiles of temperature was effected with ±8% accuracy by a novel diagnostic technique. Temperatures up to 18,500 K were observed on the axis of the plasma column, near the cathode tip, and decayed in both radial and axial directions. A sweeping microprobe was used to measure the axial and radial profiles of velocity. Velocities up to 190 m/s were recorded. The presence of a relatively colder flow surrounding the plasma column was detected. Mass and energy balances performed by taking this flow into account agreed with the measured input rates

ISSN:0001-1541    

DOI:10.1002/aic.690290206

出版商:American Institute of Chemical Engineers    

年代:1983

数据来源: WILEY

摘要:

AbstractThe relation between the velocity and concentration fields for a fully developed turbulent flow which transfers mass to a pipe wall at large Schmidt numbers has been studied. Measurements of the fluctuations of the concentration gradient and the velocity gradient were obtained simultaneously at multiple locations on the wall. Spatial scales were calculated for the low frequency velocity fluctuations by passing the measured signals through low‐pass filters. These scales are the same size as the scales of the concentration fluctuations. This result provides additional support for the notion that mass transfer to a boundary at high Schmidt numbers in controlled by low frequency velocity fluctuations which contain only a small fraction of the total turbulent energ

ISSN:0001-1541    

DOI:10.1002/aic.690290207

出版商:American Institute of Chemical Engineers    

年代:1983

数据来源: WILEY

摘要:

AbstractMass transfer between a turbulent fluid and a solid boundary is considered for the case of large Schmidt numbers. The variation of the mass transfer coefficient with time,K(t), is calculated by solving the mass balance equation using a random velocity input. An interpretation of the mass transfer process which is radically different from that given by classical approaches is obtained.

ISSN:0001-1541    

DOI:10.1002/aic.690290208

出版商:American Institute of Chemical Engineers    

年代:1983

数据来源: WILEY

摘要:

AbstractThe drag coefficients of drops of various liquids falling in air were measured experimentally. The drag coefficient was linearly related to the viscosity in the Reynolds number and viscosity range measured. Measurements also suggested there is no difference between Newtonian and non‐Newtonian liquid

ISSN:0001-1541    

DOI:10.1002/aic.690290209

出版商:American Institute of Chemical Engineers    

年代:1983

数据来源: WILEY

摘要:

AbstractMeasurements were made of the two‐dimensional flow and temperature field in a d.c. plasma jet under different operating conditions. The particle velocity and the in‐flight particle temperature were also measured for narrow cuts of alumina powders, of mean particle diameters of 18, 23, 39 and 46 μm, injected in the jet. The results are compared with the predictions of a one‐dimensional mathematical model. The measured and computed particle velocities are in good agreement. This is, however, not the case for the particle temperature where considerable differences are observed. An attempt is made to determine the parameters which are often unduly neglected in modelling work and to identify the areas where further work is

ISSN:0001-1541    

DOI:10.1002/aic.690290210

出版商:American Institute of Chemical Engineers    

年代:1983

数据来源: WILEY

摘要:

AbstractWe propose a two‐level identification strategy to detect and diagnose process faults and their causes. The strategy can be applied to processes represented by process models nonlinear in the states but linear in the coefficients. Relations to calculate both the observer for the states and the least squares estimator for the coefficients are specified in detai

ISSN:0001-1541    

DOI:10.1002/aic.690290211

出版商:American Institute of Chemical Engineers    

年代:1983

数据来源: WILEY