摘要:

AbstractHeat transfer and pressure drop were investigated for steam‐water mixtures flowing in an electrically heated horizontal duct of rectangular cross‐section. The investigation was primarily concerned with the region of high vapor fractions and mass flow rates, where two‐phase convention‐controlled heat transfer predominated.The experimental data were found to be in good agreement with those of other studies in which circular tubes were used. The data in the convection‐controlled region were correlated by equations developed from two flow models, a separated‐annular model and a homogeneous model.Two phase pressure drop data were correlated satisfactorily by the Lockhart‐Martinell

ISSN:0008-4034    

DOI:10.1002/cjce.5450390302

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

年代:1961

数据来源: WILEY

摘要:

AbstractPhysical phenomena may be described from the “microscopic” point of view, in terms of distributed parameters, or from the “macroscopic” viewpoint, using lumped parameters. Engineering correlations almost always involve lumped parameters. A lumped parameter is equal or proportional to some average value of the corresponding distributed parameter. Like any average quantity it gives no information regarding the form of the distribution. The use of lumped parameters therefore requires some assumptions, expressed or implied, regarding the form of the distribution within the system.The characteristic lumped parameters used in problems of heat transfer and fluid friction are overall or average fluxes of heat energy or momentum, arbitrarily defined as described in this paper. Common dimensionless groups, such asf,NBe,NStand others are ratios of these energy or momentum fluxes. Such dimensionless groups, since they are ratios of lumped parameters, are themselves lumped parameters. In their definition, therefore, several assumptions regarding the distributions of velocity and temperature are implicit. When these assumptions are not valid, correction factors such as diffusivity ratios or length‐to‐length ratios are needed to allow for deviations from the distributions used for reference.Using this approach the form of empirical equations becomes easy to predict. Dimensional analysis is not needed. In addition, this approach suggests that some accepted correlations may contain weaknesses not predicted by ot

ISSN:0008-4034    

DOI:10.1002/cjce.5450390303

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

年代:1961

数据来源: WILEY

摘要:

AbstractAt Reynolds numbers approaching unity the particles in a solids‐gas system acquire a turbulent motion in response to the turbulence of the ambient fluid. This regime is of particular importance and a discussion of recent theoretical and experimental attempts to describe it is presented. The reaction of the fluid phase to the presence of the particles is equally important. The extent to which the mean and turbulent properties of the fluid motion are affected by the presence of the solids phase is governed by the particle concentration and the fluid and solids Reynolds numbers. The experimental evidence is as yet inconclusive owing to the difficulty of obtaining reliable data. The theoretical attack is similarly made difficult by the need to employ mixed Eulerian and Lagrangian coordinates. A discussion of electrostatic charging phenomena has also been included and it shows that in some systems it exerts an over‐riding influence on the particle motion and momentum trans

ISSN:0008-4034    

DOI:10.1002/cjce.5450390304

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

年代:1961

数据来源: WILEY

摘要:

AbstractA general method of finding the optimal volumes, temperatures and bypass rates for a sequence of stirred tank reactors is developed. After a discussion of the method of dynamic programming, the example of a sequence of adiabatic reactors of equal volume with a single reaction is used as an illustration. A simple graphical construction for determining the optimal bypass rates is given for this case. The limiting cases of the optimal control of a batch reaction by addition of cold feed is also solved.

ISSN:0008-4034    

DOI:10.1002/cjce.5450390305

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

年代:1961

数据来源: WILEY

摘要:

AbstractThe effect of intraparticle temperature distribution on the catalytic effectiveness factor is derived, and its magnitude is estimated using an approximate solution. These calculations show that for the several cases examined the term containing the effect of temperature is less than 10% of that due to the concentration effect.

ISSN:0008-4034    

DOI:10.1002/cjce.5450390306

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

年代:1961

数据来源: WILEY

摘要:

AbstractThis, report develops computational techniques that are useful in multicomponent distillation. A design parameter, (∂n/∂N)sis introduced which is numerically equal to the number of theoretical plates required to do the work of one total reflux tray at the bottom of the enriching section. For a minimum sized tower, (∂n/∂N)sis legs than 3.5. Economic conditions may permit values as high as 6.The ratio of the number of theoretical trays,n, to the minimum number,N, for the combined enriching and stripping sections, including reboiler and condenser, and the ratio of the reflux leaving the enriching section, Ls, to the minimum reflux, LMs, can be found from:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{c}{n/N = \frac{{2.303(\partial n/\partial N)_s \log _{10} (\partial n/\partial N)_s}}{{(\partial n/\partial N)_s - 1}}} \\{L_s /L_{M_s} = \frac{{(\partial n/\partial N)_s}}{{(\partial n/\partial N)_s - 1}}} \end{array} $$\end{document}A total of 36 sets of minimum reflux data in multi‐component systems were correlated with an average error of −4% in the ration/Nby these equations.Since (∂n/∂N)sis related to the relative volatility and the compositions of the counterflowing liquid and vapor streams at the bottom of the enriching section, the refluxLscan be found from a feed tray balance. A procedure is provided for evaluatingLsafter a value for the design parameter ha

ISSN:0008-4034    

DOI:10.1002/cjce.5450390307

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

年代:1961

数据来源: WILEY

摘要:

AbstractFactorial design of leaching tests done on pegmatitic uranium ores is an efficient method of studying the effects of changes in process variables, as the required information may be obtained with a minimum expenditure of effort.The results of a complete five factor, two level, factorially designed experiment in which an “acid‐cure” technique was used are discussed. The data obtained in two, half replicate, five factor, two level, tests in which a percolation leach technique was used, establish base levels of variables for further economic study of uranium recovery from Higginson Lake pegma

ISSN:0008-4034    

DOI:10.1002/cjce.5450390308

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

年代:1961

数据来源: WILEY

摘要:

AbstractWhen electrodes are inserted in a fluidized bed of conductive coke particles, an electric current can be passed with sufficient power to raise the bed to a high temperature. This device becomes a chemical reactor when the fluidizing gas is appropriately chosen. The reaction conditions which obtain in such a reactor are sometimes of especial value in producing favorable yields in chemical reactions.The design and operating characteristics of laboratory scale units are described. These are usually Vycor tubes fitted with rubber stoppers through which electrical and gas connections are made. Even with such simple apparatus, it is possible to operate at 1500°C.Several chemical reactions have been studied in detail using reactors of this type. Among these are some which show commercial promise, such as the high temperature reaction of ammonia and hydrocarbons to form hydrogen cyanide

ISSN:0008-4034    

DOI:10.1002/cjce.5450390309

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

年代:1961

数据来源: WILEY

ISSN:0008-4034    

DOI:10.1002/cjce.5450390301

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

年代:1961

数据来源: WILEY