bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wall sampling in slurry systems
Authors: Nasr‐El‐Din H. , Shook C. A. , Esmail M. N. 
Published: March 2009

AbstractAn experimental study of the errors arising in side wall sampling has been conducted. A two‐dimensional model provides qualitative explanation of these errors but, unlike probe sampling, quantitative prediction of sampling efficiency is not possible because the flow to the sampler is more complex. The experiments show that serious errors in concentration or particle size distribution can arise unless the particles are fine, the concentration is high and a very high sampling velocity is used. A projection extending from the pipe wall was found to improve sampling efficiency. However this improvement was of marginal value because the complex nature of the flow precluded a simple theoretical prediction.
Gas holdup above the bed surface and grid gas jet hydrodynamics for three phase fluidized beds
Authors: Catros A. , Bernard J. R. , Briens C. , Bergougnou M. A. 
Published: March 2009

AbstractA three dimensional column was used to study the hydrodynamics of a three phase system: air, water and 3 mm glass beads. Various effects of the grid jets on bed hydrodynamics were investigated for both increasing and decreasing liquid superficial velocities. Three regimes were observed: spouted bed, spouted fluidized bed and three phase fluidized bed.The hydrodynamics of the two phase region above the bed was also studied. The gas holdup increased when the gas superficial velocity was increased but decreased when the liquid superficial velocity was increased. A correlation for the estimation of the gas holdup as a function of gas and liquid superficial velocities was established.
Laminar flow diffusion of power‐law fluids in a tube with arbitrary order heterogeneous and homogeneous reactions
Authors: Chang Ching‐Yuan , Chern Yeong‐Tsong 
Published: March 2009

AbstractSolutions for isothermal laminar flow diffusion with simultaneous heterogeneous and homogeneous reactions in a tube are extended to the case of non‐Newtonian power‐law fluids with arbitrary order reactions. Finite‐difference methods are employed to yield the solutions. Special emphases are placed on the role of the reaction product characterized by two unique parameters, the diffusivity ratio and the stoichiometric coefficient ratio. Effects of reaction rate kparameters on the unique parameters, the diffusivity ratio and the stoichiometric coefficient ratio. Effects of reaction rate parameters on the system performance are also presented, showing a crossover behavior of the Sherwood number. The results are in good agreement with known solutions for systems of Newtonian fluids with first‐order reactions.
Non‐dissociative adsorption on activated carbon: A statistical rate theory of interfacial transport
Authors: Ghosh Ajit K. , Sridhar T. 
Published: March 2009

AbstractThe statistical rate theory of interfacial transport, describing the non‐dissociative adsorption of gases onto solid adsorbents is evaluated. Transient experimental adsorption data of acetylene, vinyl coloride and hydrogen chloride onto activated carbon are compared with the model predictions. The statistical rate theory is found to be much superior to the conventional Elovich equation. Equilibrum thermodynamic properties for gas‐solid system have also been estimated suing the model.
Adsorption from multicomponent gas mixtures on the heterogeneous surfaces of solid catalysts
Authors: Wojuciechowski B. W. , Hsu C. C. , Rudzinski W. 
Published: March 2009

AbstractA generalized isotherm for adsorptio of gas mixtures with different molecular sizes on heterogeneous surfaces has been derived. The isotherm retains the from of the equation derived by Crickmore and Wojciechowski (C‐W). The single heterogeneity factor in the C‐W equation is replaced by a product Ciαi which accounts for the combined effect of surface heterogeneity and molecular size. The term is non‐separable by experiment but the concept is very important in considering catalytic reactions where a great variety of molecular sizes and types can be adsorbed on the actalyst surface.
Liquid phase decomposition of t‐butyl derivatives over solid acidic catalyst
Authors: Takahashi Takeshige , Hong Wu Zi , Tashiro Masashi 
Published: March 2009

AbstractThe de‐t‐butylation of some t‐butyl‐derivatives has been carried out in the liquid phase using amorphous silica alumina and HY type zeolite. The deactivation coefficients obtained in liquid phase were about 10 to 100 times as large as those in the vapor phase de‐t‐butylation of t‐butylbenzene. The activation energies for the reaction of the phenolic derivatives were nearly the same as that for the vapor phase de‐r‐butylation. However, the activation energies for the di‐t‐butyl derivatives were almost doubled. The activity of HY type zeolite was lower than that of the silica alumina, but the shape selectivity of the former was observed in the reaction of p‐t‐butyl‐o‐phenol.
Catalytic reactions of n‐hexenes on amorphous silica‐alumina
Authors: Abbot J. , Wojciechowski B. W. 
Published: March 2009

AbstractReactions of n‐hexenes on 80/100 mesh amorphous silica‐alumina have been studied in a plug flow reactor at 405°C, and compared with results previously obtained using HY and H‐ZSM‐5. The dominant primary reaction is skeletal isomerization while the initial selectivity for cracking is very low compared to that on the zeolite catalysts. The dimerization‐cracking reaction, the major cracking process on the zeolites, was not a primary reaction on amorphous silica‐alumina. This and the slowness of reactions leading to paraffins and dehydrogenated species is attributed to the small number of strongly acidic sites on the amorphous material.
Kinetic studies of wheat straw hydrolysis using sulphuric acid
Authors: Ranganathan Srinivasan , Macdonald Douglas G. , Bakhshi Narendra N. 
Published: March 2009

AbstractThe kinetics of cellulose and hemicellulose hydrolysis of wheat straw was studied using both isothermal and non‐isothermal techniques in a batch reactor. Reactions were carried out between 100 and 210°C and product sugars were analyzed using a Bio‐Rad HPX‐87P liquid chromatographic column. A simple first order series reaction model was used for both cellulose and hemicellulose hydrolysis reactions and kinetic parameters were obtained for the Arrhenius rate equations for three different sulphuric acid concentrations (0.5, 1.O and 1.5%). Activation energies remained constant with acid concentration but the pre‐exponential factors showed an increase with acid concentration. To minimize the amount of experimental data required and to achieve a unique solution to the kinetic parameters, the technique of combining isothermal and non‐isothermal reaction data was studied.
Effect of aspect ratio on bed expansion in pirticulate fluidization
Authors: Mazumdar P. , Ganguly U. P. 
Published: March 2009

AbstractThe effect of aspect ratio on the degree of bed expansion in particulate fluidization has been studied. For unicomponent solid systems of crushed particles with water as the fluidizing medium, the degree of bed expansion is independent of aspect ratio. Coal and limestone have been taken as the solid while aspect ratio has been varied from 1.10 to 4.67. The result is in full conformity with previous work with steel balls.
Coupled two‐phase mass transfer to spherical drops — Trace gas absorption and oxidation by a single drop
Authors: Ramachandran S. , Kleinstreuer C. , Altwicker E. R. 
Published: March 2009

AbstractMass transfer across gas and liquid boundary layers into the core of drops with liquid phase first order chemical reaction has been analyzed for spherical drops in the Reynolds number range of 50 < Reg < 400. The realistic and computationally efficient simulation of this gas absorption system is applicable in a variety of engineering fields including gas‐liquid mass transfer in drops and sprays.The present paper deals with the fluid mechanics and mass transfer with chemical reaction of a single drop. In computer experiments good predictive agreement has been achieved with measured data. The theoretical results were generalized to show the influence of three major system parameters: Peclet number Peg or Pel Damköhler number Da and the distribution coefficient at the gas‐liquid interface, M, on mass transfer and to demonstrate the importance of coupled gas‐ and liquid‐phase resistances to gas absorption under practical conditions.
Screening and identification of extractive fermentation solvents using a database
Authors: Kollerup Finn , Daugulis Andrew J. 
Published: March 2009

AbstractThe ethanol fermentation has been studied as a model system for end product inhibition and extractive fermentation. Examination has been done on the basis of theoretical considerations, as well as experimental evaluation. For the latter case, a database has been developed in order to screen more than 1,500 solvents for their suitability as extractants in the system solvent‐ethanol‐water. Based on this screening, 62 solvents have been tested with yeast cultures to determine experimentally such important parameters as biocompatibility, distribution coefficients and phase stability. Fifteen of these solvents have proven to be completely biocompatible, while 26 were completely toxic, the remaining solvents showing different degrees of inhibition.In this paper, the theoretical and experimental procedures involved in the systematic screening of extractive fermentation solvents will be outlined. Also, some heuristic criteria will be presented that allow for an evaluation of solvent biocompatibility a priori.
On the measurement of coal liquefaction kinetics
Authors: Özüm B. , Moschopedis S. E. , Chakrabartty S. K. , Oǧuztöreli̇ M. N. 
Published: March 2009

AbstractCoal liquefaction kinetic rate constants play an important role in the design and operation of liquefaction reactors. The objectives of this work are to present a comparative review of the measurement techniques which have appeared in the recent literature, and to analyse briefly some of the kinetic models used in the measurements of the rate constants. A mathematical technique to analyse multicomponent‐multireaction kinetic schemes using the data obtained from autoclave (closed) and continuous stirred tank reactors (CSTR, open) is discussed.
Fluidised bed gasification of a metallurgical coke with CO2/N2 Mixtures
Authors: Stubington John F. , Barrett Denis , Duong H. Thanh 
Published: March 2009

AbstractThe gasification of a metallurgical coke with CO2/N2 mixtures in a 0.1 m diameter fluidised bed has been studied over the temperature range 810–1050°C. The rate of gasification was found to be essentially kinetically controlled, with negligible influence of fluidisation parameters below 1000°C.A number of flow models were assessed. The plug flow model was found to be the simplest model which could predict the experimental results, giving similar results to the more complex two‐phase flow model of Davidson and Harrison (1963).For the range of conditions studied, the simple nth order reaction model was used to determine a best value of the reaction order of 0.8. For this combination of flow and reaction models, an activation energy of 197 kJ/mol was deduced from the experiments, in agreement with packed bed results and literature data.Very simple models can be used to predict the experimental results within the range studied.
Development of sampling and analytical procedures for biomass gasifiers
Authors: Esplin G. J. , Fung D. P. C. , Hsu C. C. 
Published: March 2009

AbstractA design of a sampling train suitable for the analysis of raw producer gas from biomass gasifiers is presented. The sampler was designed to allow sampling of gas streams at a wide range of temperatures and tar concentrations and to facilitate the separation of gases, particulate, tar and aqueous fractions. The procedure for the collection, separation and analysis was evaluated on the results obtained from the biomass fluidized bed gasifier located at B.C. Research, Vancouver, B.C.
Concentration profiles in laminar‐flow tubular reactor with wall injection
Authors: Jain S. C. , Chen B. H. , McMillan A. F. 
Published: March 2009

AbstractThe effect of wall injection on the concentration profiles for chemically reacting systems under laminar flow conditions has been analysed. Results indicate significant variation in radial concentrations for second‐order reactions, but little effect for zero‐order and first‐order reactions.
Drainage of thin films beneath parabolic and spherical caps
Authors: Jeelani Shaik A. K. , Hartland Stanley 
Published: March 2009

AbstractThe variation in film thickness h with time t for the approach of an infinite sphere to a plane horizontal surface (β = 1) or of two infinite spheres (β = 2) is given by:

For finite spherical caps with edge radius rf the variation is much more complicated and also involves the parameter S = βr2f/2aho. Fortunately, the gradient

is the same in both cases, providing t is large enough (the critical value of t increases with decreasing S). A similar result is obtained if the spherical cap is approximated by a parabolic cap with apex curvature 1/a equal to that of the sphere. In both cases the variation in dynamic pressure close to the centre of the draining film is identical and independent of the radial position where the dynamic pressure falls to zero when the film thickness is small.MacKay and Mason (1961) measured the film thickness beneath a sphere of finite size approaching a horizontal plane and experimentally verified Equation (b). This does not however, as they assumed, prove the correctness of Equation (a), which only applies to infinite spheres. The more complicated equations describing the approach of finite spheres and parabolic caps are presented in this paper.
Mixing characteristics and gas hold‐up of a bubble column
Authors: Guy C. , Carreau P. J. , Paris J. 
Published: March 2009

AbstractThe hydrodynamic behavior of a bubble column has been studied for various Newtonian and non‐Newtonian liquids (water, glycerol, carboxymethylcellulose and polyacrylamide solutions). The mixing time, the power consumption, the circulation time and the gas hold‐up have been measured in a cylindrical column (diameter: 0.254 m, height: 0.9 m) for three air sparger plates with different numbers and distributions of 1 mm diameter orifices. It is shown that the mixing efficiency decreases as the viscosity or the shear‐thinning and elastic properties of the liquid increase. The viscosity of the liquid has little influence on the gas hold‐up which is, however, strongly affected by the sparger plate characteristics and increases as the liquid phase becomes more elastic. A model for predicting gas hold‐up is proposed.
Measuring and modelling lateral solid mixing in a three‐dimensional batch gas—solid fluidized bed reactor
Authors: Berruti F. , Scott D. S. , Rhodes E. 
Published: March 2009

AbstractA 0.27 m diameter fluidized bed reactor has been designed to allow experimental measurement of the axial and radial mixing behaviour of the solids.A unique method has been developed which permits the continuous determination of solid tracer concentration with time at different radial and axial positions within the fluidized bed.Solids mixing has been described by a model in which vertical mixing is instantaneous and lateral mixing occurs by dispersion.The lateral solids dispersion coefficients have been evaluated at various operating conditions from the experimental results of tracer concentration versus time. Based on the results, a modification of an existing correlation is proposed.
Hydraulic, mass transfer and heat transfer performance comparison between ordered bed packing and sieve trays
Authors: Spagnolo D. A. , Chuang K. T. 
Published: March 2009

AbstractThe Girdler–Sulfide (GS) heavy water production process has traditionally used tray columns because of their large size. In recent years, the chemical industry has extended the use of packing to larger columns because of economic and performance advantages. A pilot scale study was thus initiated to compare the hydraulic, mass transfer and heat transfer performance of an ordered bed packing (Mellapak) with sieve trays operating under GS process conditions. Mellapak offered lower pressure drops, higher throughputs and improved heat transfer over sieve trays. However, benefits to deuterium mass transfer were only marginal in large diameter columns.
Mass transfer in a single‐hole tray column
Authors: Neuburg H. J. , Chuang K. T. 
Published: March 2009

AbstractA theoretical model for deuterium exchange in the H2S/H2O system was derived to describe mass transfer in the bubble formation, bubble displacement and bubble breakup regions above a single‐hole tray in an 8 cm diameter transparent column. The model was applied to data measured at 31°C in the pressure range of 790 to 2000 kPa and in a wide range of gas and liquid flows. High speed cinematography was used to measure bubble diameters, bubble formation times and bubble contact times in the liquid, all of which are parameters in the mass transfer models.Results show that for single‐hole trays and the major part of mass transfer occurs in the upper surface of the froth where bubbles disengage from the liquid. However, when the same model is applied to pilot plant sieve trays, it is shown that the bulk of mass transfer takes place in the region where bubbles are ascending in the froth. The tray efficiencies predicted by the model agree well with measured values.
Electrochemical mass transfer at a fixed bed of spheres under forced convection induced by counterelectrode gas bubbles
Authors: Sedahmed G. H. 
Published: March 2009

AbstractRates of mass transfer were measured at a cathode consisting of a fixed single layer of spheres stirred by oxygen evolved at a horizontal disc anode placed below. The rate of mass transfer was found to increase by a factor of 2–6.5 over the natural convection value, depending on the operating conditions.A mathematical model based on the surface renewal theory was formulated to explain the mechanism of mass transfer at gas stirred electrodes. A new electrochemical reactor built of a series of cells arranged vertically in a cylindrical container, each cell consisting of a screen gas‐evolving counterelectrode placed below a fixed bed working electrode, is proposed as offering an efficient way of stirring with no external stirring power consumption.
The computer‐derivation of thermodynamic equations Part I. First and Second Derivatives for Simple Systems
Authors: Farah N. , Missen R. W. 
Published: March 2009

AbstractAn algorithm is described for the systematic derivation of expressions for first and second thermodynamic derivatives involving the use of Jacobians. The algorithm is implemented by means of a list‐processing language in conjunction with a commercially available symbolic mathematical system for use with a microcomputer. The algorithm is intended to replace tables and procedures currently used “by hand”. Attention is limited in this paper to simple systems with two degrees of freedom, but the algorithm is to be extended ultimately to chemical systems subject to equilibrium constraints. Examples are given to illustrate the procedure.
A new approach to thermal integration of distillation sequences
Authors: Kattan M. K. , Douglas P. L. 
Published: March 2009

AbstractThis paper describes a new approach for synthesizing thermally integrated distillation sequences. There are two key developments in this research. First, the overall flowsheet is optimized simultaneously as opposed to the traditional technique of optimizing each tower sequentially followed by heat integration. Second, maximum energy recovery techniques are used to estimate the total energy requirements of the thermally integrated network, eliminating the need to synthesize a heat exchanger network on each function evaluation in the optimization routine. A frequently reported five component light alkane system (Rathore's Problem) was used to illustrate this approach. Optimized process flowsheets, energy savings and a comparison with literature values are presented.
The effect of geometric parameters on the structure of combined axial and Taylor‐Vortex flow
Authors: Gu Z. H. , Fahidy T. Z. 
Published: March 2009

AbstractThe variation of Taylor‐vortex flow structure with the width of the annulus between concentric cylinders has been studied in combined axial and rotating flow by a direct visualization technique using analytical indicators. The existence of inclined wavy vortex flow with specific transition paths between several wave modes is demonstrated in the low axial Reynolds number range (0 < Re < 50).
Developing and fully developed turbulent flow of drag reducing fluids in an annular duct
Authors: Shenoy A. V. , Shintre S. N. 
Published: March 2009

AbstractVelocity profiles for the inner and outer flow regions of annuli are proposed for the turbulent flow of drag reducing fluids. Theoretical expressions for friction factors are developed. From the shear stress equations and the velocity profiles, estimates for the entrance lengths are given.
Numerical calculation of particle collection by a row of cylinders in a viscous fluid
Authors: Mclaughlin Carroll , Mccomber Pierre , Gakwaya Augustin 
Published: March 2009

AbstractA method for calculating the collection efficiency of particles by a row of cylinders in a viscous fluid is presented. The Navier‐Stokes equation is solved by the finite element method to determine the carrier gas velocity field. Then, the particle equation of motion is also solved by the finite element method to find the particle velocity of impact. Finally, the collection efficiency is obtained by integration of the intercepted particles on the cylinder surface. Results of this model are compared with other theoretical models as well as with some experimental data.
Conjugate heat transfer between internal forced and external natural convections with wall conduction
Authors: Mori Shigeru , Gotoh Shinji , Tanimoto Akira , Sakakibara Mikio 
Published: March 2009

AbstractA new method which combines analytical and numerical solutions is presented for analyzing coupled transport phenomena between multiple regions. The method was applied to simulate heat transfer from hot laminar forced downward convection in a parallel plate duct to external natural convection through a finite section of one wall. Obtained numerical results showed that the longitudinal wall conduction markedly relaxed the thermal interaction between the two convection systems. Experiments were also performed, using conducting walls made of aluminum, stainless steel and granite. Predicted temperature profiles agreed well with the experimental data.
Spouted bed drying of agricultural grains
Authors: Viswanathan K. , Lyall M. S. , Raychaudhuri B. C. 
Published: March 2009

AbstractIt is shown that the presence of a “slotted draft tube” results in reduced air requirements for spouting and improved drying performance. Experimental data are presented on batch as well as continuous spouted bed drying of wheat, paddy, maize and peas. The variables studied are feed moisture content (Qo), inlet air temperature (To), bed mass hold‐up (Mp), inlet superficial air velocity (uo) and bed diameter (Dc) in batch drying, and the above variables and solids feed rate (Fs) in continuous drying. The data on average overall drying rate, ϕm, in kg moisture evaporated per unit time per kg bed solids, is found to be correlatable as ϕm, = k (50Qo + 0.118To − 12.5) 10−5, and the single parameter k is presented for wheat, paddy, maize and peas for both batch and continuous modes of spouted bed drying. The correlation obtained should be useful in dryer design for the grains studied as well as for other similar materials.