摘要:

AbstractA study was made to determine the effect of mass transfer on the drag coefficients of freely‐moving aerodynamically smooth spheres, accelerating in a co‐current turbulent air stream. The particles consisted of celite impregnated with liquid sulphur dioxide and varied in diameter from 0.184 to 0.989‐inch. Accurate time‐distance data were obtained with a new particle‐tracking technique which allowed the quantitative measurement of drag coefficients for relative turbulence intensities varying from 5 to 30%.The range of Reynolds numbers studied was from 2100 to 29,800, which, because of the effect of free‐stream turbulence, forms a part of the super‐critical flow regime. The results have thus been compared with the previously reported drag data for solid non‐evaporating spheres in a similar flow region.Mass transfer was found, in general, to decrease the super‐critical drag on a sphere and to reduce the influence of relative turbulence intensity. This alteration in momentum transfer is probably due to a reduction in the skin friction and to a pressure increase in the wake of an e

ISSN:0008-4034    

DOI:10.1002/cjce.5450460201

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

年代:1968

数据来源: WILEY

摘要:

AbstractAn analytic expression has been deduced for the ultimate velocity of a free particle in a vertically oscillating fluid by evaluating asymptotic forms of Floquet's solution to the Mathieu equation arising from the nonlinear Langevin equation describing the particle‐fluid interactions. Using general Mathieu theory it has been rigorously demonstrated that directional particle motion in a gravitational field can be retarded by sinusoidal fluid oscillations when the particle‐fluid drag law is of square form. The earlier Rayleigh‐Ritz approximation (Houghton 1966) for the retarded particle velocity is shown to be in good agreement with the results of Mathieu theory, as summarized in graphical

ISSN:0008-4034    

DOI:10.1002/cjce.5450460202

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

年代:1968

数据来源: WILEY

摘要:

AbstractVariations of the level of mixing in a flow system have been investigated as a function of the following parameters: diameter, shape and speed of the agitator, feed rate and position of the feed inlet.At agitator speeds inferior to a critical value, a minimum level of mixing is observed which depends on the position of the feed inlet. At speeds superior to the critical value, the level of mixing increases linearly with agitator speed, at a given feed rate, until conditions of perfect mixing are reached. The critical agitator speed and the position of each straight line depend on the agitator size. A modified Reynolds number makes possible a more general correlation.At a given agitator speed, superior to the critical value, the level of mixing decreases as the feed rate increases, due to the smaller amount of energy imparted by the agitator per unit mass of feed. The effect of agitator shape on the level of mixing is rather pronounced as it affects the flow patterns inside the reservoir.

ISSN:0008-4034    

DOI:10.1002/cjce.5450460203

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

年代:1968

数据来源: WILEY

摘要:

AbstractLe systéme étudié consiste en un réservoir cylindrique vertical muni d'un agitateur coaxial à turbine et de chicanes. L'entrée de l'alimentation et la sortie de l'effluent se trouvent dans l'axe du réservoir, la première sous l'agitateur et l'autre en surface.On a utilisé un modèle proposé par Cholette et Cloutier pour caractériser les paramètres de l'agitation. A une vitesse donnée de l'agitateur, la présence de chicanes a pour effet de diminuer le niveau d'agitation. Cette diminution est une fonction complexe de la largeur des chicanes. La présence de chicanes entraǐne également une diminution du court‐circuit.Le couple varie avec le niveau d'agitation; il augmente en présence de chicanes et encore plus pour de grands diamètres de l'agitateur.Les auteurs proposent une représentation des différents circuits internes qui permettent d'expliquer les

ISSN:0008-4034    

DOI:10.1002/cjce.5450460204

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

年代:1968

数据来源: WILEY

摘要:

AbstractVelocity and angle profiles emanated by turbine type impellers were measured in both air and water using a hot wire anemometer probe and two and three dimensional pitot tubes. Pumping capacities were then calculated from the velocity data. The effect of the rotational speed and the dimensions of the turbine was investigated.

ISSN:0008-4034    

DOI:10.1002/cjce.5450460205

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

年代:1968

数据来源: WILEY

摘要:

AbstractAn experimental study was conducted with a 40 kw. direct‐current nitrogen plasma jet confined in an 8.00‐in. i.d. graphite chamber. The heat transfer rates were determined at a test section located 10.5‐in. below the entry of the jet to water‐cooled 0.625 and 1.000‐in. diameter spheres at temperature differences of up to 5,000°f. and over the Reynolds number ranges of 600 to 4,300. The data were correlated in terms of the Nusselt and Reynolds numbers, with gas properties taken at the bulk temperature. The high intensity of turbulence increased the heat transfer rates to above most of those previously reported, and Reynolds number exponents typical of turbulent systems wer

ISSN:0008-4034    

DOI:10.1002/cjce.5450460206

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

年代:1968

数据来源: WILEY

摘要:

AbstractThermal conductivity measurements available in the literature for simple gases at normal pressures (approximately 1 atmosphere) were used to obtain the productk*λ, where the parameter, λ =M1/2Tc1/6/Pc2/3. Separate relationships betweenk*λ andTRresulted for monatomic, diatomic and triatomic gases.The relationships for monatomic gases can be expressed as follows\documentclass{article}\pagestyle{empty}\begin{document}$$ \left( {k*\lambda } \right)_m = 9.96 \times 10^{ - 5} \left[ {e^{0.046T} R - \frac{1}{{e^{0.046T} R}}} \right] $$\end{document}For the diatomic and triatomic gases, linear relationships resulted, when at the same reduced temperatures, theirk*λ values were plotted against (k*λ)mon log‐log coordinates. These relationships can be expressed in equation form as follows\documentclass{article}\pagestyle{empty}\begin{document}$$ \left( {k*\lambda } \right)_d = 1.105\left( {k*\lambda } \right)_m ^{1.10} \quad \left( {{\rm diatomic}\,{\rm gases}} \right) $$\end{document}and\documentclass{article}\pagestyle{empty}\begin{document}$$ \left( {k*\lambda } \right)_t = 1.02\left( {k*\lambda } \right)_m ^{1.46} \quad \left( {{\rm triatomic}\,{\rm gases}} \right) $$\end{document}Thermal conductivities calculated with these relationships have been compared with experimental values and produce an average deviation of 2.8% for the monatomic gases (219 points), 4.3% for the diatomic gases (282 points) and 4.6% for the triatomic gases (242 points).In this treatment, helium and hydrogen do not follow the general pattern and consequently these substances have been treated sepa

ISSN:0008-4034    

DOI:10.1002/cjce.5450460207

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

年代:1968

数据来源: WILEY

摘要:

AbstractRates of heat transfer associated with the evaporation of water from the surface of porous particles into air were measured for both packed and fluidized beds. Direct measurements of the temperature on the surface of these particles permitted the calculation of the heat transfer coefficient, hg, for both packed and fluidized bed systems. An effectiveness factor, χ, has been introduced to account for the non‐plug flow characteristics of fluidized beds. This quantity has been used to define the rate of particle to gas heat transfer as follows\documentclass{article}\pagestyle{empty}\begin{document}$$ q = h_{t^b } \chi aV\left( {\Delta t} \right)_m $$\end{document}where (δt)mrepresents the log‐mean temperature difference across the bed and hg bis the heat transfer coefficient at the initiation of two phase fluidization defined as the “bubble point”. An analysis of the experimental measurements indicates that\documentclass{article}\pagestyle{empty}\begin{document}$$ \chi = g^{0.115} $$\end{document}wheregrepresents the ratio of the heat transfer factor of the fluidized bed to that corresponding at the bubble point of this bed. This effectiveness factor has also been related to the void fraction ratio as follows\documentclass{article}\pagestyle{empty}\begin{document}$$ \chi = \frac{{1.063}}{{\left( {\varepsilon _f /\varepsilon _p } \right)^{0.314} }} $$\end{document}where ϵt, and ϵp, are the void fractions of the fluidized bed and its corresponding packed bed arrangement. This equation applies for

ISSN:0008-4034    

DOI:10.1002/cjce.5450460208

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

年代:1968

数据来源: WILEY

摘要:

AbstractA process of extractive distillation, employing a dissolved salt rather than a liquid solvent as separating agent, was studied on a pilot plant scale. Aqueous ethanol was fractionated in a 12‐tray, bubble cap column with potassium acetate present in the liquid phase. Even relatively small concentrations of salt eliminated the azeotrope. An overhead product completely free of separating agent was obtained directly from the column. A technique is described for metering salt at a steady rate, and for achieving rapid solution of the salt in the reflux strea

ISSN:0008-4034    

DOI:10.1002/cjce.5450460209

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

年代:1968

数据来源: WILEY

摘要:

AbstractThe influence of spatially nonuniform initiation is investigated for a class of photoreactions in which diffusion of intermediates is important. The investigation is centered on a differential equation for reaction and diffusion of reactive intermediates. The circumstances are set forth under which the equation is valid for several kinetically similar reaction types. A solution is obtained for Lambert's law attenuation. The characteristics of this solution and the solution obtained by Noyes for linear attenuation are discussed. The practical consequences of these solutions are shown through illustrative calculations based on the photochlorination of tetrachloroethylene.

ISSN:0008-4034    

DOI:10.1002/cjce.5450460210

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

年代:1968

数据来源: WILEY