摘要:

AbstractA pool boiler and a forced convection loop used for studying critical heat fluxes in binary mixtures are described. The geometry of the test element is shown to be an important variable in pool boiling experiments, affecting both absolute flux values and the variation with composition. Data given for AC and DC power supplies show that the critical heat flux is relatively unaffected by the power supply source.Empirical equations of the form (Q/A)c= const.VaΔTbsubare given for benzene, toluene and acetone, which correlate the forced convection subcooled data with average deviations of 3.1%, 5.0% and 5.1% respectively.Forced convection subcooled data are given for the systems benzene‐toluene and acetone‐toluene showing the effect of composition on critical heat flux.It is concluded that, at forced convection subcooled conditions in certain concentration ranges, binary mixtures may exhibit critical heat fluxes which are higher than for either of the pure components. In this respect loop experiments are analogous to pool boiling ones. However, extrapolation from pool boiling experiments to loop conditions does not appear to be feasible under the present test condit

ISSN:0008-4034    

DOI:10.1002/cjce.5450410602

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

年代:1963

数据来源: WILEY

摘要:

AbstractMeasurements have been made of the mass transfer of naphthalene into an air stream in the presence of a standing sound wave propagated parallel to the surface. The flowrate range of the air stream was fromRe= 100 toRe= 14,000. Concentration of the ablated naphthalene in the effluent air was measured by ultraviolet spectrophotometry.At the antinode for resonant frequency of 286 cps and a sound intensity of 154 db, mass transfer enhancement occurs at flowrates up toRe= 8,000; this enhancement is as large as 180% at low flows. The enhancement increases with sound intensity, and decreases with increasing frequency.At the node, the mass transfer was reduced in proportion to the intensity. The sound flux changes both concentration and velocity profiles in the column, probably by alteration of the boundary layer. Mass transfer enhancement appears to be a function of the ratio of oscillating velocity to superficial mean velocity. The significance of oscillation amplitude in the enhancement of mass transfer is established.

ISSN:0008-4034    

DOI:10.1002/cjce.5450410603

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

年代:1963

数据来源: WILEY

摘要:

AbstractApproximate velocity profiles have been predicted for laminar, incompressible flow around solid and fluid spheres for Reynolds numbers up to several thousand. The accuracy of the predicted profiles for solid spheres has been tested in three ways. Drag coefficients, flow‐separation angles and forced‐convection transfer rates calculated from these profiles have been compared with experimental data for solid or rigid spheres. The predicted quantities oscillate about the experimental data as the Reynolds number is increased. Cross‐over points occur at Reynolds numbers of about 20, 100 and 500. The velocity profiles for fluid spheres are of little practical value above Reynolds numbers of several hundred as drop or bubble deformation is significant.Drag coefficient data for solid spheres, liquid drops and gas bubbles showing the effect of dispersed‐phase viscosity on total drag are presented. These data are correlated over the Reynolds number range, 10–100 with a viscosity‐ratio correction factor which was derived th

ISSN:0008-4034    

DOI:10.1002/cjce.5450410604

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

年代:1963

数据来源: WILEY

摘要:

AbstractFoam fractionation has been employed for inorganic and organic chemical separations, for the treatment of radioactive wastes, and as a tertiary treatment method for secondary sewage effluents. Although the general effect of the basic variables of foam separation has been established, a quantitative approach to the process has not been made. In this study, a fundamental analysis of foam separation as a mass transfer operation is presented, utilizing both equilibrium and rate concepts of mass transfer.Foam separations have been carried out employing aqueous solutions of dodecyl sodium sulphate and alkyl benzene sulphonate at concentrations ranging from 0.005 to 0.14% weight. The range of surfactant concentrations which can be handled under a given set of operating conditions is established. In the batch experiments, volumes and concentrations of the foam and residual bulk phases are presented for nitrogen rates of 200 and 320 cc./min. Flow experiments were carried out using gas rates of 320, 440 and 580 cc./min. and liquid feed rates of about 70 and 100 cc./min. In general, the concentration of the drain stream was relatively insensitive to both gas and feed rates, but the total removal rate was found to be a strong function of gas rate.

ISSN:0008-4034    

DOI:10.1002/cjce.5450410605

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

年代:1963

数据来源: WILEY

摘要:

AbstractA reduced state correlation for the coefficient of thermal expansion of water has been developed from PVT data available in the literature for the substance. The coefficient of thermal expansion was expressed in terms of reduced variables and a reduced state density correlation was developed for water. This density correlation was then utilized to develop plots of the dimensionless variable, βTc, againstTRandPafor reduced temperatures up toTR= 3.0 and reduced pressures up toPR= 20

ISSN:0008-4034    

DOI:10.1002/cjce.5450410606

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

年代:1963

数据来源: WILEY

摘要:

AbstractSpraying of silver alloy catalysts by powder flame spray and by molten alloy spray techniques is briefly described. Some of the physical properties such as density, porosity, thermal conductivity and diffusibility are listed for catalysts prepared from 8.5% calcium in silver alloy, as well as a few data on pure silver, copper and nickel. Initial rate data from the oxidation of ethylene have been compiled to show a diffusion effect within the catalyst layer, and these data have been used to calculate a diffusibility factor which is lower than a similar factor estimated from oxygen‐helium diffusion experiments. The kinetic data were obtained from catalyst strips immersed in an inert mullite powder bed fluidized with reacting air‐ethylene mixture. Heat transfer coefficients from strip to bed were estimated from the kinetic data, exothermic heats of reaction and recorded temperature differen

ISSN:0008-4034    

DOI:10.1002/cjce.5450410607

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

年代:1963

数据来源: WILEY

摘要:

AbstractWhen niobium pentachloride is exposed to moist air, hydrogen chloride is liberated and hydrated niobium pentoxide or niobic acid remains. It is believed that the rate of the reaction is controlled by the rate of diffusion of water across a layer of unidentified intermediate product of constant thickness (about 0.2 mm.). The constant thickness of the layer is maintained by the spalling and cracking of the product after it exceeds a critical thickness. Since the reaction takes place at an interface between the niobium pentachloride and the layer of intermediate, it is necessary to normalize the results for the decrease in interfacial area as the reaction proceeds. When this is done, the rate of the reaction, expressed in terms of grams of niobium pentachloride reacting per square centimetre of interface per hour, is:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Rate} = \left({7.7 \pm 0.4} \right) \times 10^4 \left({p_s /p} \right)\exp | - \left({8.1 \pm 0.6} \right) \times 10^3 |/RT $$\end{document}

ISSN:0008-4034    

DOI:10.1002/cjce.5450410608

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

年代:1963

数据来源: WILEY

摘要:

AbstractExperimental concentration profiles obtained in the separation of H2‐ D2mixtures, by selective adsorption on charcoal in a moving‐bed adsorber, were used to test the validity of semi‐rigorous adsorber design equations based on considerations of gas film diffusion (utilizing the linear driving force concept), solid phase diffusion (utilizing Fick's law) and axial dispersion.The adsorption equilibrium data and solid phase diffusivities used in the design equations were also measured directly in separate experiments, whereas the gas film and axial diffusion values were evaluated from published data(3,0)In general, good agreement was obtained between the experimental and theoretically predicted concentration profiles, except at the lowest flow rates investi

ISSN:0008-4034    

DOI:10.1002/cjce.5450410609

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

年代:1963

数据来源: WILEY

摘要:

AbstractThe prediction of chemical yield and productivity for packed tubular reactors is examined in two articles. A mathematical model and digital computing scheme are presented for reactors with several reactions, large heat effects, and heat exchange at the wall. Case studies show that yield loss depends strongly on the dimensions and flow rate adopted in reactor design.Part 1 presents a steady state reactor model based on material and energy balances formulated in partial differential equations on radial and axial space coordinates. The model allows for multiple reactions with arbitrary rate expressions and stoichiometry, axial bulk flow, radial effective diffusion and conduction, and a heat transfer resistance at the wall. Problems of scale‐up and similitude are discussed in terms of the model.Part 2 presents the numerical computing scheme and case studies

ISSN:0008-4034    

DOI:10.1002/cjce.5450410610

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

年代:1963

数据来源: WILEY

ISSN:0008-4034    

DOI:10.1002/cjce.5450410611

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

年代:1963

数据来源: WILEY