bluuebunny/crossref_metadata_2025 huggingface dataset:
Mass transfer from single gas bubble — a comparative study on experimental methods
Authors: Garbarini Gail R. , Tien Chi
Published: March 2009

A comparative study on the experimental techniques which have been used for the study of mass transfer from single gas bubble was made. The instantaneous mass transfer rates from a single carbon dioxide bubble rising through quiescent liquid medium (water) were measured using two different methods. For the first method, two movie cameras were placed on a moving platform along perpendicular directions and were used to record the position and size change of the bubble. The second method measured the mass transfer rates by recording the pressure changes in the free space at top of the bubble column, which was caused by the change of bubble size. The instantaneous mass transfer coefficients determined by either method exhibited wide scattering which is typical of work of this kind. Discussions are given on the relative merits of these two methods.
On liquid‐liquid mass transfer inside drops in a turbulent flow field
Authors: Boyadzhiev L. , Elenkov D. , Kyuchukov G.
Published: March 2009

Mass transfer in liquid‐liquid dispersions in a turbulent flow field has been investigated for the particular case where the overall process rate is governed by the diffusional resistance in the dispersed phase. Experiments with the system water‐iodine‐carbon tetrachloride have shown that the transfer mechanism in this case is similar to that for single drops at high Reynolds numbers. The results obtained show that the so‐called correlation factor R depends strongly on the turbulence of the system. This relationship can be expressed as R ˜ R2, which is valid for the mass transfer rate both in turbulent liquid‐liquid dispersions and for some cases of solute diffusion in single oscillating drops.
Kinetics of cupric oxide catalysed oxidation of propylene in a stirred reactor
Authors: Lakshmanan R. , Rouleau D.
Published: March 2009

The catalytic air oxidation of propylene to acrolein over a supported copper oxide catalyst was investigated in a continuous stirred vessel reactor between 375° and 450°C at atmospheric pressure. The effect of temperature, ratio of oxygen to propylene in feed and total feed rate (or contact time) on the conversion of propylene and the yield of acrolein were determined. It was found that with an increase in temperature, ratio of oxygen to propylene and contact time, the yield drops considerably though conversion increases.

A study of the mixing characteristics of the stirred vessel reactor was carried out by following the conversion at various stirrer speeds.

The kinetic data obtained were tested to determine the most probable model by the Hougen‐Watson method. The model that satisfactorily correlated the data describes the rate‐controlling step as the surface reaction occurring between adsorbed propylene, a vacant site and oxygen in the gas phase. The following Hougen‐Watson type rate equation has been proposed

The constants in the rate equation have been expressed as a function of temperature.
Isothermal adsorption in fixed beds
Authors: Lee Robert G. , Weber Thomas W.
Published: March 2009

Prediction of single component adsorption in a packed bed operated isothermally is accomplished through the use of a mathematical model. The model accounts for the diffusional resistance between the bulk gas and the surface of the adsorbent particles, and for the diffusional resistance within the particles. The adsorption reaction within the pores is assumed to be very rapid compared to these two rate controlling mechanisms. The model can be used for isotherms of any shape and for gaseous feeds of any concentration. The partial differential equations of the model were solved numerically. Breakthrough curves are presented for four different isotherms and for two feed concentrations. The extension of the model to handle surface diffusion is treated. The model is compared with that of Rosen ≥11, 20 and the differences are discussed.
Equilibria in binary liquid — adsorbent systems
Authors: Shelstad K. A. , Wong S. W.
Published: March 2009

Adsorption equilibrium data at 25°C. for toluene‐n‐heptane mixtures in contact with three types of adsorbent carbon, silica gel, and alumina, and for o‐xylene — m‐xylene mixtures on one carbon were correlated in terms of a capacity factor Z and a separator factor a. The capacity Z was found to be less than the pore volume and the mono‐molecular area calculated from Z was found to be smaller than the butane surface area of the adsorbent. Values obtained for a ranged from 4.74 to 10.2 depending upon the system.
Designing experiments for precise estimation of all or some of the constants in a mechanistic model
Authors: Hunter William G. , Hill William J. , Henson Thomas L.
Published: March 2009

An important experimental problem in chemical engineering is to collect data in order to estimate constants such as rate constants and activation energies which are needed, for example, in equipment and plant design. For a given amount of experimental effort, the engineer wants these constants to be estimated as precisely as possible. In this paper, we discuss statistical design procedures that might be used to accomplish this goal. Available procedures are reviewed for estimating precisely all the constants in a mechanistically based mathematical model. In addition, a new procedure is illustrated for precisely estimating only some of the constants which may be of more interest than the others.
The effect of changes in initial reactant composition on solid‐gas equilibria resulting from constant‐volume, adiabatic processes
Authors: Van Zeggeren F. , Storey S. H.
Published: March 2009

A method is given for the computation of the chemical equilibria attained by adiabatic chemical reactions in similar systems, all with the same volume and mass, as a result of changes in the initial reactant compositions. Changes in equilibrium composition and temperature are directly related to changes in the initial elemental abundances, in the form of a set of simultaneous equations. Since it is not necessary to perform complete calculations for each solution required, the solution of these equations constitutes a saving in computation. The method can be applied to solid‐gas systems. The systems must be ideal or they have to obey an empirical equation of state, wherein covolume is a function of volume only.
On the use of the imperfect tracer pulse method for determination of hold‐up and axial mixing
Authors: Øsstergaard K. , Michelsen M. L.
Published: March 2009

The imperfect pulse method is a powerful technique for experimental analysis of chemical engineering flow systems. The authors have employed this method in studies of holdup and mixing in gas‐liquid fluidized beds. In the present paper are discussed two problems connected with reduction of the experimental data obtained in such studies.

Tailing is a phenomenon that may seriously affect the accuracy of mixing coefficients determined by the imperfect pulse method. Accurate methods of data reduction, based upon analysis of moments, have been developed, and their applicability is demonstrated by analysis of experimental data.

Interphase transfer of tracer material is of particular importance in investigations of gas phase mixing in a gas‐liquid system where absorption of tracer gas into the liquid phase normally takes place. A semiempirical method is described for correction of the experimental data in such cases.
Axial mixing of liquid in a turbulent‐bed contactor
Authors: Chen B. H. , Douglas W. J. M.
Published: March 2009

The axial dispersion of liquid in a 12‐in. turbulent‐bed contactor has been investigated for three packing sizes: ½‐in., 1‐in. and 1½‐in. The gas and liquid flow rates were varied from 500 to 2700 lb./(hr.)(sq. ft.) and from 1500 to 11,000 lb./(hr.)(sq. ft.) respectively. The transient response technique using KCl solution as the tracer was employed for this purpose.

The experimentally determined residence‐time distribution curves were interpreted by means of a one‐dimensional dispersion model. The axial dispersion coefficient, DL, was found to increase with increasing gas flow rate, liquid flow rate, or packing size. In terms of Peclet number (NPe = ū dp/DL), the present data showed that NPe was dependent on Reynolds number (N, = dp ū ρ/μ), Gallileo number (NGa = dp3 ρ3 g/μ2), and reduced gas mass velocity (Δ = (G‐Gmf)/Gmf), but the ratio of the Peclet number for a turbulent contactor to the Peclet number for a fixed‐bed contactor, NPe/NPeo, depended only on Δ, and the diameter ratio dp/dt. A correlation of NPe/NPeθo with Δ and dp/dt is presented.
Mixing models with varying stage size
Authors: Fan L. T. , Chen Michael S. K. , Ahn Y. K. , Wen C. Y.
Published: March 2009

Two progression models which can be employed to represent flow systems with varying degree and mode of mixing along the direction of flow such as a shallow fluidized bed, radial flow reactors, and short tubular reactors, etc. are proposed. Residence time distributions are derived from the standpoint of stochastic processes. The use of progression models is illustrated with a second order, isothermal reaction.
Prediction of thermodynamic properties of polar mixtures by a group solution model
Authors: Ratcliff G. A. , Chao K. C.
Published: March 2009

A modified group solution model for liquid mixtures is presented. The model differs from previous models in that the Bronsted‐Koefoed congruence principle is used to describe the effect of molecular size. The model has been tested for mixtures involving paraffin hydrocarbons, alcohols and water at low pressures. Such systems involve binary mixtures of the groups methylene and hydroxyl, and are reasonably represented by the model.

Data presented enable the approximate equilibrium properties of such solutions at low pressures to be predicted at 40°C and 90°C. Interpolation and reasonable extrapolation from these temperatures should be satisfactory.
A variable‐density model of the pipeline flow of suspensions
Authors: Shook C. A. , Daniel S. M.
Published: March 2009

The turbulent flow of suspensions of fine solid particles in liquids is analyzed by assuming that the suspensions behave essentially as variable‐density single phase fluids. Friction factors are found to depend upon the distribution of solid particles within the conduit as well as the Reynolds number of the flow. Comparison of the model with experimental measurements indicates that as long as turbulent suspension of solid particles occurs, the model is a useful alternative to the empirical Durand equation for pipeline design.
Effect of a dilute “drag‐reducing” polymer solution on a float‐type flowmeter
Authors: Fvlford G. D. , Arunachalam Vr.
Published: March 2009

It has been found experimentally that very dilute polymer solutions of the type known to reduce turbulent pipe friction drag affect the calibration of “rotameter” type flow meters. This effect appears to decrease with increasing age of the solution.
Freezing of hydraulic systems
Authors: DesRuisseaux N. , Zerkle R. D.
Published: March 2009

A theoretical technique is developed for predicting the conditions under which a hydraulic system freezes shut. The investigation considers laminar liquid flow through a tube between two reservoirs. Freezing is assumed to occur within a portion of the tube having a uniform wall temperature lower than the liquid freezing temperature. Analytical results indicate the minimum allowable pressure drop which must be maintained across the system to prevent it from freezing shut. The theoretical predictions are then compared with experimental results.
Cocurrent gas‐liquid flow in horizontal tubes with internal spiral ribs
Authors: Zarnett G. D. , Charles M. E.
Published: March 2009

The flow of air‐liquid mixtures has been investigated in 3/4‐inch internal diameter Lucite tubes fitted with continuous spiral ribs having pitch‐to‐diameter ratios of 1.57 and 2.79. Descriptions and photographs of the flow patterns are presented for reasonably wide ranges of gas and liquid flow rates. The main effect of the spiral rib was to move the gas phase away from the tube walls. The flow patterns were classified as bubble, plug, slug‐stratified, slug‐semiannular and slug‐annular. The pressure gradient data were successfully correlated with the Lockhart‐Martinelli parameters, although the resulting curves showed small displacements from the Lockhart‐Martinelli correlation for smooth tubes.
Dissolution mass transfer in a turbine agitated baffled vessel
Authors: Nienow A. W.
Published: March 2009

Mass transfer coefficients were measured for the dissolution of crystalline electrolytes suspended in a baffled vessel by means of disc turbines. A 3‐fold range of density differences, a 5‐fold range of diffusivities and a 50‐fold range of particle size were covered and the effect of impeller speed, size and clearance from the base was studied.

The increase in coefficent with speed is both a function of the clearance and solid density and size and is difficult to quantify. However, in the most economic configuration of small clearance and large impeller, this is not of great importance since the coefficient increases but slowly with speed and the minimum suspended coefficient can be calculated. This is done by means of a slip velocity theory which has been extended to include larger particles, which allows for the effect of concentration dependent physical properties and which is based on the impeller speed at which particle suspension occurs.
A method for estimating inter rivulet mixing
Authors: Porter K. E. , Stephens G. K.
Published: March 2009

A method is presented for estimating inter rivulet mixing in liquid running in film flow down a packed bed. The method is based on comparing an experimentally measured tracer distribution with the theoretical distribution at several levels below the plane of tracer injection. The change in the number of traced rivulets is then estimated statistically. Experimental results for water running over Raschig rings show that inter rivulet mixing may be estimated from two experimentally determined parameters, a collision frequency factor and a mean size of rivulet.
Interprétation cinétique des mesures d'ignition dans le cas des systèmes réactionnels gaz‐solide
Authors: L'Homme G. A.
Published: March 2009

Cette étude propose une interprétation quantitative du phénomène d'ignition en vue de déterminer leg paramètres cinétiques des réactions chimiques exothermiques du type: gaz + solide → gaz.

Deux méthodes cinétiqueg sont préconisées dans le cas où le processus chimique se produit dans le régime cinétique, et leurs modalités d'application pratique sont discutées. La première méthode est à coefficient de transfert thermique gaz‐solide variable d'une mesure d'ignition à l'autre, tandis que la seconde est à coefficient de transfert thermique constant: elles permettent de déterminer la cinétique réactionnelle à partir de la mesure des conditions expérimentales régnant à l'ignition.

Ces méthodes sont ensuite appliquées avec succès à un système réactionnel de géométrie, d'hydrodynamique et de mécanisme cinétique compliqués: l'oxydation catalysée d'un noir de carbone, mesurée dans une installation thermo‐gravimétrique.
The analysis of residence time distribution measurements using laguerre functions
Authors: Anderssen A. S. , White E. T.
Published: March 2009

The residence time distribution of a flow system can be determined from the response of the system to an arbitrary input, by a technique invoving Laguerre functions. This technique is convenient for digital computation, and is comparable in accuracy with other methods. The effects of the nature of the flow system, the arbitrary input, and the presence of noise are considered.
The optimization of the catalytic oxidation of sulphur dioxide in a multi‐bed adiabatic reactor
Authors: Chartrand G. , Crowe C. M.
Published: March 2009

A multi‐bed adiabatic reactor for the catalytic oxidation of sulphur dioxide was optimized using maximum conversion as the criterion and with plant data from Canadian Industries Limited, Hamilton, Ontario. Different combinations of the following parameters were varied: number of beds, inlet temperature to each bed, bed depth and air dilution before each bed. The optimization techniques used and compared for efficiency were: dynamic programming, gradient search, Hooke and Jeeves' pattern search and the discrete maximum principle.

The optimum conversions were found to be quite insensitive to considerable variation in feed temperature, air dilution and catalyst distribution. An improvement in the plant conversion of 0.25% was predicted.
Optimum estimation of process parameters using pseudo‐random binary signals with application to mixing inside a packed tower
Authors: Woodburn E. T. , King R. P. , Everson R. C.
Published: March 2009

A technique is described for the design of a test signal such that the parameters, defined by the axial mixing model for a packed tower, can be estimated with the greatest accuracy from experimental records.

Methods for calculating the effect of additive noise, usually associated with small amplitude signals, on computed correlation‐, spectral‐and amplitude ratio estimates are discussed.

Designed experiments were performed on a 10‐in. I.D. packed tower by the injection of a radioactive tracer into the gas phase. Peclet numbers for both dry and irrigated beds are reported.