摘要:

AbstractGas‐liquid interfacial areas were measured for cocurrent downward flow of the two‐phase mixtures in a 2.54 cm ID open tube. The liquid phase was a dilute solution of aqueous sodium hydroxide and the gas phase was a mixture of air and carbon dioxide. Interfacial areas were determined by sampling the liquid phase and applying the technique of absorption with fast chemical reaction. Data were obtained in the froth flow regime and in the falling bubbly film regime which does not occur in horizontal or vertical upflow. Measured interfacial areas ranged from 0.7 to 2.5 cm−1. These values are lower than those for downflow in a 10‐mm tube(10)by a factor of about two, suggesting a dependence on the tube diameter. A correlation in terms of Jepsen's frictional energy dissipation parameter\documentclass{article}\pagestyle{empty}\begin{document}$ \left( {\frac{{\Delta P}} {{\Delta L}}} \right)(V_L ^ \circ + V_G ^ \circ ) $\end{document}is presented for the interfaci

ISSN:0008-4034    

DOI:10.1002/cjce.5450580201

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe profiles of waves travelling over the free surface of a liquid film, falling along an inclined flat wall, have been calculated, using a non‐linear technique of dynamic analysis. The wave profiles range from a simple nearly sinusoidal shape with small amplitudes, to a complicated profile close to solitary waves with high amplitudes. The results agree with earlier experimental observations, and are consistent with the results of the hydrodynamical theory of stability. Some of the solution trends have been observed to a lesser extent in previous non‐linear theories. It is clear that the phenomena associated with wave formation on a falling film, observed under the experimental conditions, arise because the problem is essentially non‐l

ISSN:0008-4034    

DOI:10.1002/cjce.5450580202

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe silhouette of a sessile drop submerged in a transparent bulk phase appears to possess a contact angle of 180° with a plane solid support, when the drop is separated from the solid surface by a thin film of surrounding fluid. A computer‐aided analysis of the generalized sessile drop form leads to an explicit equation for interfacial tension dependent only on drop height (from apex to solid support) and the magnitude of the drop equatorial diameter. The equation is valid for a wide range of physically realizable drops. Measurements of drop profile coordinates or the location of the drop equator are not required for the use of the method, leading to improvements in accuracy relative to current practi

ISSN:0008-4034    

DOI:10.1002/cjce.5450580203

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

年代:1980

数据来源: WILEY

摘要:

AbstractA simple model is presented for the prediction of hold‐up and slip velocity in spray columns in which the continuous phase moves counter‐current to the dispersed phase. Analysis of 591 data points for 16 systems from 8 different sources show that the slip velocity is given in terms of the average drop diameter of the drop swarm and the physical properties of the system by:\documentclass{article}\pagestyle{empty}\begin{document}$$ \frac{{V_s^2 }}{{\phi g}} = 2.725\frac{{\Delta \rho }} {{\rho _ c }}\left( {\frac{{1 - \in _d }} {{1 + \in _d ^{1/3} }}} \right)^{1,834} $$\end{document}for 7

ISSN:0008-4034    

DOI:10.1002/cjce.5450580204

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

年代:1980

数据来源: WILEY

摘要:

AbstractLe travail présenté concerne le transfert thermique entre un septentin hélicoïdal et des liquides newtoniens, ou non‐new‐toniens agités par une turbine à 4 pales inclinées dans une cuve cylindrique.La viscosité effective des fluides rhéofluidisants est définie par le modèle de Metzner‐Otto combiné à l'équation rhéolo‐gique d'Ellis. Le transfert thermique dans les fluides newtoniens en régime turbulent est représenté avec la meilleure précision par les équations:\documentclass{article}\pagestyle{empty}\begin{document}$$ Nu_{d_s } = (0,07457\,{Re} ^{0,5} + 0,000150\,{Re} )\,\Pr ^{1/3} \, Vi^{1/4} \,{\rm en}\,{\rm pompage}\,{\rm haut} $$\end{document}\documentclass{article}\pagestyle{empty}\begin{document}$$ Nu_{d_s } = (0,05183\,{Re} ^{0,5} + 0,000154\,{Re} )\,\Pr ^{0,40} \, Vi^{1/4} \,{\rm en}\,{\rm pompage}\,{\rm bas} $$\end{document}Dans le domaine non‐newtonien, en pompage bas, l'équation ci‐dessous permet une estimation très précise du coefficient d'échange thermique en régime d'établissement\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{l} {Nu_{d_s } = 0.02425\,{Re} _{NN} ^{0,701} \,\Pr _{NN} ^{0,311} \, Vi_{NN} ^{0,163} } \\ {{Re} _{NN} :80

ISSN:0008-4034    

DOI:10.1002/cjce.5450580205

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

年代:1980

数据来源: WILEY

摘要:

AbstractA study was made of the energy utilization efficiency in a d.c. plasma toich operating with argon at atmospheric pressure at a power level of 10‐25 kW. Calorimetric measurements of the energy lost to the cathode, anode and that remaining in the plasma jet showed that the torch efficiency was about 40 to 50%. It increases with an increase of the plasma gas flow rate but decreases with an increase of the current intensity. The electrode spacing was found to have no significant influence on the efficiency over the range investigated. The torch efficiency could be substantially improved by a reduction of the anode size. The addition of small concentrations of a diatomic gas such as nitrogen improved the efficiency to about 65% and increased the total power dissipated in the torc

ISSN:0008-4034    

DOI:10.1002/cjce.5450580206

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

年代:1980

数据来源: WILEY

摘要:

AbstractThis paper presents a theoretical investigation on the solidification of a low Peclet number fluid flow in the thermal entrance region of a round pipe. The velocity is assumed laminar and fully developed throughout the pipe and the fluid temperature is taken to be uniform at X = −∞. The pipe wall is adiabatic at X ≤ 0 and is cooled convectively at X ≥ 0. The exact solution in the liquid and solid phase are obtained by using the method of separation of variables and constructing two sets of orthonormal functions from the nonorthogonal eigenfunctious at X = ± 0.The solutions including temperature distributions, liquid‐solid interfaces and Nusselt numbers for the parameters, Bi = 20, 4, 0.4, 0.04, Pe = 1, 3, 5, 10, 20, 30, ∞ and the superheat ratios, ξ = (1 − θf)/θf, θf= 0.1, 0.2, …, 0.9 are presented in this paper. The length of ice‐free zone xfcorresponding to Pe = ∞ are in excellent agreement wi

ISSN:0008-4034    

DOI:10.1002/cjce.5450580207

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

年代:1980

数据来源: WILEY

摘要:

AbstractIsothermal breakthrough curves were determined for ethylene‐carbon dioxide mixtures in nitrogen fed to a bed of Linde 5A 1/8″ molecular sieve pellets. The system had previously been shown(11)to have azeotropic equilibrium compositions in the range − 50 to + 50°C and at a total solute pressure of 1.07 kPa. The present column experiments covered the range −15 to + 50°C and total solute pressures of 0.40 ‐ 2.67 kPa. Three major types of adsorption breakthrough curves were observed. In two of these the solutes broke through simultaneously and could not be separated by extending the bed length. Carbon dioxide exceeded and then dropped back to the feed concentration in some of these runs, in others the inlet value was reached directly. In the third type of curve, the sorption fronts did separate, but the light component did not always exceed the feed concentration in the classical manner of a Langmuir solute. A tentative explanation of these phenomena is given in terms of equilib

ISSN:0008-4034    

DOI:10.1002/cjce.5450580208

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

年代:1980

数据来源: WILEY

摘要:

AbstractGas phase CO2concentration profiles were measured in two sizes of bubble columns with different gas spargers and with the liquid phase (tap water) entrance or exit (cocurrent or countercurrent flow) at a certain height above the gas distributor. The region of high turbulence intensity near the sparger was locally separated from the region of high mass transfer rates in such columns. A modified back flow cell model was applied to describe the experimental data. The kL‐values obtained from fitting the profiles agreed for both columns and, in addition, did not differ for cocurrent and countercurrent flow. This is in remarkable contrast to previous findings(10,11). The large influence of the gas sparger on the kL‐values even in tall bubble columns was thus demonstrated. It is thought that this may probably be one of the reasons why correlations for prediction of kLdiffer so significan

ISSN:0008-4034    

DOI:10.1002/cjce.5450580209

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

年代:1980

数据来源: WILEY

摘要:

AbstractThe oxygen transfer characteristics of gas‐aqueous electrolyte solution dispersions have been studied in a laboratory‐size, mechanically‐agitated tank equipped with a 6‐flat blade turbine of standard dimensions (DI/T = 1/3). The effects of mechanical agitation power input per unit volume (Pg/V), gas superficial velocity (vS) and aqueous‐phase ionic strength (Γ) upon the overall volumetric mass transfer coefficient (kLa) and the liquid‐phase mass transfer coefficient (kL) are presented. In the range of 0.2 ≤ Γ ≤ 1.2 kmol(ions)/m3, the results of this study indicate that kLincreases with increasing Γ is independent of P/V for Pg/V<2000 W/m3but decreases with increasing Pg/V above that level and is independent of vsover the range of gas velocities studied. On the other hand, KLa was found to be dependent on all three variables

ISSN:0008-4034    

DOI:10.1002/cjce.5450580210

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

年代:1980

数据来源: WILEY