摘要:

The objective of the present work was to study the effects of axial dispersion on the behavior of the annular bed reactor using the methanation of carbon monoxide as the test reaction. It was found that the reactor is nearly-isothermal with and without axial dispersion, but the concentration profiles differ significantly. The effects of dispersion on the behavior of the annular bed are similar to those in the conventional fixed bed reactor, but appear to be much stronger.

ISSN:0098-6445    

DOI:10.1080/00986448408940094

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The performance of pitched blade turbines in a gas-liquid dispersion has been studied. The two-phase hydrodynamics, gassed power consumption and mass transfer properties have been examined using six blade open turbines with blade angles from 30 to 60 degrees to the horizontal, mounted for down flow.

ISSN:0098-6445    

DOI:10.1080/00986448408940095

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The kinetics of the methanation of CO have been analysed for oscillatory behavior. For a scheme involving dual site adsorption of H2, analytical conditions for isothermal oscillations have been derived. They show differences between a homogeneous and a heterogeneous surface of the catalyst. A common feature is that the ranges of oscillatory behavior on both types of surfaces are independent of the partial pressure of H2. However, they differ in the effect of the partial pressure of CO, and this fact is utilised to suggest a discrimination method.

ISSN:0098-6445    

DOI:10.1080/00986448408940096

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

It is possible that the critical boiling heat flux of mixtures exceeds that of the components considerably. This effect has been attributed to the slowing down in bubble growth rate caused by the exhaustion of the volatile component near the vapor-liquid interface (theFeffect) and the retardation of bubble coalescence due to surface tension gradient caused by the evaporation of component of lower surface tension (theMeffect). The growth and coalescence of vapor bubbles are dynamic processes. The surface tension of a fast stretching surface of a binary mixture is higher than the static value because the component of lower surface tension cannot diffuse to the adsorbed layer promptly. This dynamic effect is represented quantitatively by aYfunction.

ISSN:0098-6445    

DOI:10.1080/00986448408940097

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Processes during melting from a horizontal cylindrical heat source of uniform surface temperature embedded in ice have been studied experimentally. The volume of the melt and its shape were photographed at different times for various constant temperatures of the heat source. At early times and under all conditions, the melt occupied a cylindrical annulus. At later times free convective motion caused pear-shaped melt contours which pointed downward when the temperatures of the heat source were below 7°C and upward when the temperatures were above 8°C. Instabilities in cellular natural convection motion resulted in waviness of the interface. The location and magnitude of these ripples were found to depend on the temperature of the heat source and the melt layer thickness. Shadowgraph techniques were used to determine local heat transfer coefficients at the heat source surface.

ISSN:0098-6445    

DOI:10.1080/00986448408940098

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Experimental measurements were made of fully developed friction factors for laminar and turbulent flows of dilute aqueous solutions of Polyox (WSR-301) in a square duct.

ISSN:0098-6445    

DOI:10.1080/00986448408940099

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The influence of a pseudoplastic non-Newtonian fluid upon the hydrodynamic performance and mixing parameters of a concentric tube air-lift fermenter has been studied using a range of dilute xanthan gum solutions (0-0.5% weight by volume). Liquid circulation times vary in a complex pattern with increasing gum concentration. At low concentrations, circulation was more; rapid due to drag reduction whilst at the highest concentrations circulation times were increased. The column voidage decreased with increasing gum concentration and bubbly flow in the riser was replaced by slug flow. For all gum concentrations the effective dispersion coefficient for a single passage around the loop was increased relative to tap water. An improved radio-pill flow follower system for hydrodynamic studies is described.

ISSN:0098-6445    

DOI:10.1080/00986448408940100

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The feasibility and effectiveness of the sensing and correlating on-line differential pressure fluctuations across a fluidized bed as a diagnostic tool for malfunction of the distributor were experimentally tested by varying the extent and location of the blockage of the distributor openings. The results show that the direct observations or recordings of fluctuating signals and their statistical properties computed on-line, namely 80% fluctuating interval and standard deviation, are sensitive indicators of malfunction of the distributor.

ISSN:0098-6445    

DOI:10.1080/00986448408940101

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Interfacial stresses arising from the transfer of an interfacial tension-lowering solute (Marangoni effects) or the presence of an electric field may significantly alter the interfacial velocity of a moving droplet with consequent effects upon the rate of convective mass exchange between the drop and the external medium. The present theoretical study considers separately the Marangoni and electric field effects and delineates the conditions under which mass transfer enhancement should be observed. For Peclet numbers in the range of 10–100, enchancement is predicted for a Marangoni to Peclei number ratio of 100 or for a dimensionless electric velocity of 0.1, As an example, numerical results for a Peclet number of 50 indicate an increase of approximately 20% in the mass transfer coefficient for either a Marangoni number of 5000 or a dimensionless electric velocity of 0.5 for phases of comparable transport properties and solute solubilities.

ISSN:0098-6445    

DOI:10.1080/00986448408940102

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

For circulation in axi-symmetric (cylindrical) bubble columns, the recently developed mathematical model25,26has been used along with the criterion of minimum circulation strength to determine the height of each circulation cell in a tall column. This is then used to derive a theoretical expression, first of its kind, for gas hold-up inside a bubble column. The predictions of this equation as well as the equation derived here for axial liquid velocity at column axis have been compared with available data and the comparison is found to be excellent for both the variables. An explicit relation is derived for the average liquid circulation velocity. The model is also used to derive an expression for liquid axial dispersion coefficient which compares almost exactly with Deckweret al.'s4correlation.

ISSN:0098-6445    

DOI:10.1080/00986448408940103

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor