bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic parameter determination in monoculture and monosubstrate biological reactors
Authors: Rizzuti L. , Augugliaro V. , Dardanoni L. , Torregrossa M. V.
Published: March 2009

The kinetic parameters of a biological reactor, operating under monoculture and monosubstrate conditions, have been determined. Pure cultures of Nocardia corallina and Pseudomonas fluorescens species have been used with phenol as the only organic carbon source. The experimental runs have been carried out both in a batch and in a continuous stirred reactor.

The batch results have been interpreted by zero order kinetics in phenol and first order kinetics in biomass. The kinetic‐constants have also been calculated. The activation energy has been determined only for the Nocardia species. Using this strain, the continuous reactor, working without biomass recycle, has confirmed the first order kinetics with respect to biomass.
The products of cumene cracking on an amorphous silica alumina
Authors: Marczewski M. , Wojciechowski B. W.
Published: March 2009

A detailed analytical study of the products of cumene cracking over amorphous silica alumina shows that the mechanism of cracking over these catalysts is identical to that observed over crystalline LaY and HY at various levels of exchange. Additional analytical details are developed in this work and are used to elaborate on the previously proposed reaction network for this reaction. In particular we find that hydrogen and propane appear as secondary products in the cracking reaction network. We also find that within the limits of our measurement all the observed coke is formed from product propylene.
An explicit method of design of non‐isothermal tube‐wall reactor with volume change
Authors: Goyal S. K. , Esmail M. N. , Bakhshi N. N.
Published: March 2009

An analysis of a tube‐wall reactor with varying volume is considered under turbulent flow conditions for the case in which both the kinetic and diffusional resistances are important. The implicit molar flux expression is approximated by three successive approximations and the mass and energy balances are combined to obtain a single explicit design equation. This equation takes the form of a simple numerical integration which requires only physical and chemical properties of the inlet gas and reactor operating conditions. The method also predicts the temperature and heat flux along the reactor length. Comparison of the model predictions with a limited number of previous experimental results is good.
A fundamental study on recovery of copper with a cation exchange membrane: Part 1 — Ion exchange equilibria between cupric and hydrogen ions
Authors: Kojima Toshinori , Furusaki Shintaro , Takao Kenji , Miyauchi Terukatsu
Published: March 2009

It is possible to concentrate metal ion against the gradient of its concentration through a cation exchange membrane. The membrane has a high ion exchange capacity and is hydrophilic, therefore a rapid transfer rate of ions is expected.

Ion exchange equilibrium data between cupric and hydrogen ions for sulfuric and nitric acid systems are obtained and analyzed quantitatively for concentrations of dissociated cupric and hydrogen ions.
A fundamental study on recovery of copper with a cation exchange membrane: Part 2 — Transfer rate of copper and hydrogen ion through a cation exchange membrane
Authors: Kojima Toshinori , Furusaki Shintaro , Saito Kyoichi
Published: March 2009

Transfer rates of copper and hydrogen ion through a cation exchange membrane were measured experimentally for the systems of Cu/H‐SO4 and Cu/H‐NO3. Transfer rates of anions in the membrane were also measured, and they were negligible compared to those of the cations. Cupric ion and hydrogen ion transfer in a ratio of 1:2 and in opposite directions. The self‐diffusion coefficient of cupric ion in the membrane is obtained from the transfer rate of copper in high concentrations of sulfuric or nitric acid solutions using the equilibria data obtained in our previous work. The coefficient of the hydrogen ion is similarly obtained.
Liquefaction of coal by SRC‐II process: Part III: Reactivity of liquefaction products
Authors: Singh Chandra P. P. , Carr Norman L.
Published: March 2009

Data from experimental studies of the reactivities of SRC‐II liquefaction products, in the absence of coal, are analyzed. A general quantitative validation of the new kinetic model for SRC‐II coal liquefaction (Singh et al., 1981 a) is obtained by very good agreement between model predicted and measured yields. This shows that the new kinetic model provides a reasonable representation of the overall intrinsic process of SRC‐II coal liquefaction and hence, it can be used to explore the regions of process conditions far away from those obtained under normal SRC‐II operations.
Surface activity of foam fractions of a calcium lignosulphonate
Authors: Keirstead K. F. , Caverhill L. , De Kée D.
Published: March 2009

Successive foam fractionation has been used to divide a processed calcium lignosulphonate into tractions differing appreciably in surface activity. Static surface tension has been measured by the de Nouy tensiometer and surface tension aging by the sessile bubble (photographic) method. The effect of concentration on surface tension has been determined. The effect of pH at 1% concentration on dynamic surface tension has been determined on freshly prepared solutions.
A new velocity profile model for turbulent pipe‐flow of power‐law fluids
Authors: Shenoy A. V. , Saini D. R.
Published: March 2009

A new velocity profile model for turbulent flow of non‐Newtonian power‐law fluids in smooth pipes has been proposed, following the approach of Stein et al. (1980) for Newtonian fluids. The merit of the model, as different from all earlier works, lies in its ability to predict a zero velocity gradient at the centreline for all values of the pseudoplasticity index n. The predictions of the model when compared with the work of Bogue and Metzner (1963) have shown good agreement.
Estimation of vapor pressure from normal boiling point of hydrocarbons
Authors: Dutt N. V. K.
Published: March 2009

The Antoine equation is used to propose a simple method for the prediction of vapor pressure of hydrocarbons. This study on 218 compounds belonging to different homologous series revealed that (for each series of compounds): (i) the constant A of the Antoine relation is nearly the same for all the compounds, and (ii) the constants B and C can be related linearly to the normal boiling point. The result of the approach is Equation (7). Comparisons with the methods of Lee and Kesler (1980), and API Data Book (1978) show that the method described in this paper is a good alternative when normal boiling points are the only data available.

On a employé l'équation d'Antoine pour proposer une méthode simple servant à prévoir la tension de vapeur des hydrocarbures. Cette étude, qui porte sur 218 composés appartenant à différentes séries homologues, a permis d'établir (pour chaque série de composés) les points suivants: (i) la constante A de l'équation d'Antoine est pratiquement la měme pour tous les composés; (ii) on peut relier linéairement les constantes B et C au point d'ébullition normal. L'équation (7) résulte de cette approche. Des comparaisons faites avec les méthodes de Lee et Kesler (1980) et avec les données que contient l'API Data Book indiquent que la méthode décrite peut ětre substituée avantageusement aux méthodes précitées, lorsque les points d'ébullition normaux sont les seules données disponibles.
Hydrodynamic transport of cylindrical capsules in a vertical pipeline
Authors: Latto B. , Chow K. W.
Published: March 2009

Data are presented on the flow phenomena associated with the hydraulic transport of right cylindrical capsules, having d/D and L/d ratios, and relative density in the range of 0.49 to 0.82, 4 to 14, and 1.15 to 2.7 respectively, in a 7.6 cm 1.D. vertical pipeline with flow Reynolds numbers up to 3.6 × 105. On the basis of the experimental results the effect of the individual pertinent variables which affect the velocity ratio Rv, pressure gradient ratio Rp and the unit energy requirement E for the capsule are discussed. Semi‐empirical correlations between the capsule velocity and the capsule gradient and the pertinent variables of the system are also presented.
Breakup of jets in power law non‐newtonianndashnewtonian liquid systems
Authors: Kitamura Yoshiro , Takahashi Teruo
Published: March 2009

Non‐Newtonian effects on the breakup of jets into drops were experimentally studied for power law fluidNdashNewtonian systems under the condition of zero jet velocity relative to the continuous phase. While laminar breakup lengths of Newtonian jets in non‐Newtonian liquids agree with the prediction from the stability analysis for Newtonian systems, non‐Newtonian jets in Newtonian liquids are less stable than Newtonian jets. Experimental diameters of drops formed from jets in NewtonianNdashnon‐Newtonian and in non‐NewtonianNdashNewtonian systems are in good agreement with the prediction based on stability analysis for Newtonian systems.
Determination d'un champ de vitesses par anemometrie a films chauds dans des domaines a turbulence elevee application a des installations de decantation et d'Agitation
Authors: Gourdon C. , Et J. Costes , Domenech S.
Published: March 2009

The authors present a study of experimental methods which permit the determination of the turbulent hydrodynamic characteristics of the flow within settling and agitation units. The measurements have been made by thermal anemometry implying one and three hot films. The processing of the experimental data obtained on‐line in real time permits the average velocities, the turbulent fluctuations, the turbulent lengths and the dissipation rate to be obtained.
Dynamic analysis and simulation of a helium‐heated steam reformer
Authors: Miyasugi Takeshi , Kosaka Shinichi , Suzuki Akira
Published: March 2009

This paper deals with the dynamic characteristics of a helium‐heated heat‐exchanger type steam reformer with catalyst tubes of industrial size. A nonlinear dynamic model was developed based on algebraic and ordinary differential equations which describe material, component and energy balances. This model was numerically linearized around an operating point. In addition, an auto‐regressive model was obtained from experimental input‐output data in which the inputs were perturbed simultaneously using pseudo‐random binary sequences. Experimental data obtained by step and PRBS testing were used for comparison with the simulated responses. The comparison showed that the simulated responses agreed reasonably well with the experimental data.
Modeling of shallow fluidized bed reactors: II. Analytical and numerical solutions
Authors: Chang C. C. , Rong S. X. , Fan L. T.
Published: March 2009

A general dynamic model derived previously for shallow fluidized bed reactors with continuous solids flow has been extended. The model includes explicitly the convective and dispersive flows of solids in the lateral direction of the bed. The performance of the fluidized bed zinc sulfide roaster is simulated by solving the resultant dynamic governing equations. Steady‐state analytical solutions are obtained after simplifications of governing equations. The numerically obtained transient solutions approach these analytical solutions as time increases. A series of computations has been carried out to examine the effects of significant parameters, including the bubble size, Peclet number, crossflow ratio, Dämkohler number and superficial velocity of the fluidizing gas, on the performance of the shallow fluidized bed reactor.
Wood liquefaction: Extended batch reactions using raney nickel catalyst
Authors: Boocock D. G. B. , Mackay D. , Lee P.
Published: March 2009

Extended batch reactions, in which poplar is treated at 340°C in the presence of Raney nickel, water and hydrogen, give oil in yields of 36‐41% with oxygen contents of 12‐17%. Methane and carbon dioxide formation, hydrogen utilisation and cracking of the oil are favoured by fresh Raney nickel. There is some competition for methane and carbon dioxide production, higher hydrogen pressures favouring the former in the presence of fresh catalyst. Efficient mass transfer increases hydrogen utilisation and lowers the oil viscosity. It is concluded that Raney nickel has no significant advantage over other more convenient forms of nickel.
Liquefaction of coal by SRC‐II process: Part V: Dynamic thermal behavior of the reactor
Authors: Singh Chandra P. P. , Carr Norman L.
Published: March 2009

Criteria for identification of the unstable or stable nature of the steady state based on the reactor temperature response to step changes in feed temperature, and a dynamic thermal simulation of SRC‐II reactors are developed. These are used in the analysis of a dynamic SRC‐II reactor experiment to confirm its unstable operation under normal process conditions. The simulation is used further to study the sensitivity of reactor temperature to changes in feed temperature and to variations in the total heat capacity of the reactor vessel and insulation materials. It is shown that, under normal SRC‐II process conditions, it would take about an hour for the reactor temperature to change by ± 10°C, if no controls were used. With quench gas manipulation, the reactor temperature could be maintained within ± 1°C even for a sustained small perturbation in the process conditions. Therefore, in spite of its unstable character, the SRC‐II reactors can be readily operated with quench gas manipulation without incurring any major temperature control problems.
Some aspects of liquid‐solid fluidized beds
Authors: Rao K. V. K. , Prakash S. G.
Published: March 2009

Hydrodynamic characteristics of randomly packed fluidized beds were investigated using particles of different sizes and densities fluidized with water.

The minimum fluidization velocity was found to be independent of the initial bed height. The minimum fluidization velocity was found to be

Bed expansion followed the Richardson Zaki relationship and the exponent 'n' has been correlated as:
The uranium fuel cycle: Some aspects of the physics, chemistry and measurement of radon and thoron daughters
Authors: Phillips Colin R.
Published: March 2009

Much effort has been devoted world‐wide towards minimizing exposure to radon and thoron daughters in the exploitation of nuclear energy. In this work, the behaviour of radon and thoron daughters after formation from their gas precursors is discussed, together with optimally designed measurement and dosimetry methods for assessing alpha radiation exposure in uranium mines and mills, in buildings and in the environment. The interaction of radon and thoron daughters with aerosol particles, which is very important in determining the fate of the airborne radioactivity, can be described better in terms of activity‐size distributions than by use of the commonly applied concepts of “attached” and “unattached” fractions. Further, the properties of the aerosol‐daughter system are shown to depend upon humidity and the presence of trace gases, which serve as electron sources to neutralize the newly‐formed positive daughters. Finally, the mechanisms of release of radium and radon from ore and soil are discussed. The significance of the various conclusions to practical situations is emphasized.
Characterization of chemisorbed species in CO/H2 and CO2/H2 reactions. Evolutive behaviour of the species
Authors: Hindermann J. P. , Deluzarche A. , Kieffer R. , Kiennemann A.
Published: March 2009

By applying the chemical trapping method to the hydrocondensation reaction of carbon monoxide, we propose a reaction scheme with some novel interesting features. In the chemisorption of CO on Ni/SiO2, Ni/Al2 O3, Co, Co/Al2 O3 we detected species bonded both through the C and O ends of the molecule. This chemisorbed CO can be the intermediate of the dissociation of CO or lead to the formation of a formyl species by reaction with hydrogen. The competition of these two reactions can lead to hydrocarbons or to alcohols.
The higher alcohol synthesis over promoted Cu/ZnO catalysts
Authors: Smith Kevin J. , Anderson Robert B.
Published: March 2009

Alkali oxides added to methanol catalysts increase the formation of ethanol, n‐propanol and isobutyl alcohol. This result has been known for many years, yet few quantitative studies have been reported in the literature. Data obtained on a commercial copper‐zinc oxide catalyst promoted with K2 CO3 are presented and compared with published work. The optimum promoter concentration was about 0.5% by weight. The H2 to CO feed ratio was important in determining the higher alcohol selectivity. The rate of production of isobutyl alcohol varied as p p while for methanol, ethanol and n‐propanol both exponents were positive and less than 1.6. Decreasing the hydrogen to carbon monoxide ratio from 2 to 0.5 more than doubled the isobutyl alcohol selectivity. Chain growth schemes predicting the higher alcohol selectivity are presented and estimates of the parameters are given.
RTD for diffusion‐free laminar flow of non‐newtonian fluids through coiled tubes
Authors: Saxena A. K. , Nigam K. M. , Nigam K. D. P.
Published: March 2009

The residence time distribution (RTD) for diffusion‐free laminar helical flow of non‐Newtonian fluids has been numerically computed for values of the power‐law index from 0.2 to 2.0. Experimental verification is also provided. Excellent agreement is also shown with independently calculated RTD's appearing in the literature.
Oxygen mass transfer in three‐phase fluidized beds working at large flow rates
Authors: Alvarez‐Cuenca M. , Baker C. G. J. , Bergougnou M. A. , Nerenberg M. A.
Published: March 2009

The published literature on gas mass transfer in three‐phase fluidized beds indicates that most of the research done in the last two decades has been carried out at low superficial velocities and/or volumetric flow rates. These experimental limitations are reflected in the current understanding of these systems. In this investigation, performed at large gas and liquid velocities and flow rates, the behaviour of three‐phase fluidized beds of 0.1, 0.3 and 0.5 cm diameter glass beads has been studied.

Computer‐made contour diagrams, obtained from the mapping of the oxygen concentration in the column have proven to be an effective probing technique. These diagrams permit the description of flow patterns and bed hydrodynamic properties otherwise not observable with tracers.

The use of concentration and pressure profiles complements the observations made with the contour diagrams. At low gas and liquid velocities the concentration profiles are S‐shaped. As Vgand Vlincrease the three absorption zones, observed in those S‐shaped profiles, become two zone similar to those observed in bubble columns. The interface between the dense bed and dilute phase is characterized by an unusually high mass transfer activity.
Fluidized bed expansion as a result of biomass growth
Authors: Wang S‐C , Tien Chi
Published: March 2009

A relationship which is capable of predicting the height of a fluidized bed with the extent of the biomass growth at the surface of the fluidized particles is proposed. The application of this relationship for the determination of one of the biological parameters of waste water treatment is demonstrated.
Bitumen hydroprocessing: Effects of metal loading and promoters in Mo‐Al2 O3 catalytic systems
Authors: Kriz J. F.
Published: March 2009

Athabasca bitumen and a heavy gas oil (345−525°C) derived from it were used in a high‐pressure continuous‐flow system to evaluate catalytic effects of metal loading in hydroprocessing and to assess the role of promoters represented here by cobalt and sodium. A method that can be used for analysis of these effects is suggested. The two feedstocks are compared in view of the expected catalyst performance and requirements in each case. It was found that desirable effects of promoters were greatest at low temperatures and with catalysts having low total metal loading. Desirable effects of catalysts having high molybdenum loading were intensified with increasing temperatures. These trends were similar with both feedstocks but the effects were much less pronounced with bitumen than with the gas oil. The need for an effective hydrogenation component was identified.
A quantitative theoretical treatment of the fischer tropsch synthesis
Authors: Taylor P. D. , Wojciechowski B. W.
Published: March 2009

A generalized scheme for product distribution in Fischer Tropsch synthesis in the absence of non‐kinetic effects due to diffusion, shape selectivity, catalyst bifunctionality (e.g. synthesis‐cracking catalysts), etc. is presented. The derivations reproduce the Schulz‐Flory distribution in one limit and go on to generalize the work of Anderson in predicting the distribution of methylated species in the synthesis product. Formulae for molar distributions, weight distributions and weight distribution modes are presented. It is shown that special cases of the generalized distributions lead to methanol production or methanation as well as predicting other, as yet unreported, product compositions.
A general criterion to test the relative importance of intraparticle and external heat and mass transfer resistances in porous catalysts
Authors: Doǧu Timur
Published: March 2009

A general criterion is developed for testing the relative importance of intraparticle and external, concentration and temperature gradients on the observed rates, for reactions catalyzed by porous solids. The criterion is applicable to any multiple reaction system and to reactions conforming to any rate law. The applicability of such criteria is extended to reaction systems with highly nonlinear temperature and concentration dependence, by taking into‐account the higher order terms in the Taylor expansion of the rate expressions in the derivation.
Comparisons of the yields and properties of the oil products from direct thermochemical biomass liquefaction processes
Authors: Beckman David , Elliott Douglas C.
Published: March 2009

Several different direct thermochemical biomass conversion processes are compared based on the results of an experimental program using standard wood and peat feedstocks. The program was part of the International Energy Agency, Biomass Liquefaction Test Facility project. The operating conditions of the processes compared differed greatly. General correlations of the properties of the oils produced from these processes are made based on the severity of the operating conditions. Important parameters in considering process severity are temperature, pressure, time at reaction conditions and added reactants or catalysts.
Multistage continuous cultivation of blue‐green alga spirulina maxima in the flat tank photobioreactors with recycle
Authors: Samson Réjean , Leduy Anh
Published: March 2009

Spirulina maxima was continuously cultivated in four 64‐liter flat tank photobioreactors in cascade, under continuous 30 klx fluorescent light and nonaseptic condition, in an industrial grade synthetic medium which bubbled with atmospheric air. The increase in the number of stages resulted in the higher biomass concentration and allowed operation with a dilution rate D higher than the alga specific growth rate μ. However, multistage operation does not permit a significant increase in productivity. The recycling of the all culture medium with biomass increased the net productivity of the first two stages of the multistage system. The flat tank design offered great advantages over other geometrical configurations by occupying less space for indoor cultivation, minimizing the water loss by evaporation, and permitting a greater flexibility in construction, installation, and operation. This system was operating continuously for two years in our laboratory for indoor mass production of S. maxima biomass. The flat tank configuration gave the highest areal productivity Pa = 60.5 g/m2·d and highest volumetric productivity Pv = 1.17 g/L·d when operated as a single stage continuous cultivation with high solid recycle. These values are the highest ever reported for any indoor or outdoor mass production system for S. maxima.
Comparison of primal and dual solution methods for the chemical equilibrium problem using GRG and sensitivity analysis
Authors: Ruda M. M. , Thompson D. W.
Published: March 2009

The calculation of the composition of a reacting mixture when it reaches equilibrium can be regarded as a dual Geometric Program; there is a related primal Geometric Program with fewer variables than the dual. Both primal and dual formulations were compared using the Generalized Reduced Gradient (GRG) algorithm for systems containing 8, 10 and 24 reacting species. The primal proved to be faster (30%) than the dual, and more robust.

A sensitivity analysis method suggested by Rijckaert (1974) was tested and the results were compared with re‐solving the original problem. Sensitivity analysis was faster than re‐optimization (50%) but the accuracy of the results depended strongly on the particular problem.
Equilibria of H2S and CO2 in triethanolamine solutions
Authors: Jou F.‐Y. , Otto F. D. , Mather A. E.
Published: March 2009

The equilibrium solubility of H2S and CO2 has been measured in 2.0, 3.5 and 5.0 mol/L triethanolamine solutions. Data were obtained at temperatures of 25°, 50°, 75°, 100° and 125°C at partial pressures of the acid gases ranging from 0.01 to 6360 kPa. Enthalpies of solution were calculated from the solubility data.
The equilibrium phase properties of selected mesitylene binary systems: Mesitylene—methane and mesitylene—carbon dioxide
Authors: Huang Sam. S.‐S. , Robinson Donald B.
Published: March 2009

Vapor and liquid equilibrium phase compositions have been determined at 310.9, 394.3, and 477.6 K for the mesitylene–methane binary system and at 310.9, 338.7, 394.3, and 477.6 K for the mesitylene–carbon dioxide system. At each temperature, the pressure ranged from the vapor pressure of mesitylene to about 15 MPa, although in the case of the mesitylene–carbon dioxide system, pressures were extended to the vicinity of the critical region at about 18 MPa. The data were used to calculate equilibrium ratios for each component in the binary system.
Coal gasification condensate water: Thermodynamic modeling of gas quench effluent
Authors: Mcaskill R. D. , Bhattacharyya D. , Kermode R. I.
Published: March 2009

The partial oxidation products from a coal gasification process may contain substantial quantities of tars, phenols, ammonia, H2S, CO, CO2, H2, and water vapor. Cooling below the dew point produces condensate water which must be treated before it can be reused or discharged into the environment.

A rigorous computer model based on equilibrium thermodynamics has been developed to predict gas and condensate composition for one or more quench steps. Recycle as well as addition of fresh water to one or more stages has been included. Condensate quantities and composition as a function of quenching temperature are calculated for three gasification conditions. A flow diagram for multi‐stage effluent treatment before reuse or discharge is proposed.
Investigation of a fixed‐bed pilot plant reactor by dynamic experimentation. Part 1. Apparatus and experimental results
Authors: Baiker Alfons , Bergougnan Michel
Published: March 2009

A non‐isothermal, non‐adiabatic fixed‐bed pilot reactor specially designed for fast measurement of axial and radial temperature and concentration profiles during dynamic experiments is described. The pilot plant is interfaced to a process computer and facilitates conducting different types of dynamic experiments, such as those with simultaneous un‐correlated periodic changes of the process variables. This type of dynamic experiments proved to be most efficient for collecting the data necessary for reactor modelling. Axial and radial temperature and concentration profiles in the fixed bed were measured during catalytic hydrogenation of toluene on an industrial nickel catalyst. Peak shaped perturbations were employed to study the parametric sensitivity of the reactor behaviour and to estimate the reaction kinetics.
Investigation to develop methods for removal of oxygen from coals
Authors: Cooke N. E. , Khandhadia P. S. , Furimsky E.
Published: March 2009

Several inorganic reducing agents of various chemical characteristics have been tested to see if they reduce the oxygen contained in coal. It was found that oxygen content of coals decreased when they were heated in only water (blank runs). The treatment with the reducing agents containing sulphur did not increase the oxygen removal over that achieved in the blank runs. However, it appears that the ferrous salt catalytically deoxygenated both the lignite and bituminous coals.
Effectiveness factor under cyclic operation of a reactor
Authors: Jain A. K. , Hudgins R. R. , Silveston P. L.
Published: March 2009

Results are reported on the influence of intraparticle diffusion on the measured rate of reaction under a condition where the feed composition is changing periodically. The specific application is to cyclic operation of an ammonia synthesis reactor.

The effectiveness factor calculated relative to the steady‐state kinetic rates for the time‐average feed condition for fine particles was higher than the comparable steady‐state effectiveness factor as a result of the rate improvement due to cycling.

The effectiveness factor calculated relative to the time‐average rate of reaction under cyclic operation for the fine particles was much less than unity and similar numerically to the steady‐state effectiveness factor. The cycling effectiveness factor by either definition varied with cycling conditions because of the complex interaction of cycling parameters.
The effect of liquid viscosity on gas holdup in a vertical pipe
Authors: Weiss R. G. , Foster N. R. , Clark K. N.
Published: March 2009

The effect of liquid viscosity on gas holdup in a 15.1 mm diameter vertical pipe was assessed over the viscosity range 0.00092‐1.670 N s m‐2. Gas holdup increased with increased liquid viscosity. The sensitivity of holdup to changes in viscosity was slight at low viscosity but was markedly increased at higher viscosities.

Gas holdup was found to be well described, over the viscosity range studied, by the empirical equation:
Turbulence model predictions of the radial jet — A comparison of κ‐ϵ models
Authors: Wood P. E. , Chen C. P.
Published: March 2009

The (κ‐ϵ) turbulence closure model has become a widely used means of predicting turbulent fluid flows. In this paper the turbulent radial jet, the round jet and the plane jet are calculated in their similarity regions using various versions of the (κ‐ϵ) model to determine which is the most satisfactory for both plane and axisymmetric flows. The most general predictions were obtained using a model which contained additional terms to account for the effect of irrotational strains on the production of turbulence energy. Additionally, detailed mean velocity profiles and turbulence kinetic energy profiles of the radial jet are compared to the available experimental data.
Characteristics of Taylor vortex structure in combined axial and rotating flow
Authors: Gu Z. H. , Fahidy T. Z.
Published: March 2009

The sequential form of the axial displacement of inclined Taylor vortices and their progressive degeneration to horizontal streaks due to the increasing dominance of axial flow is demonstrated via an analytical indicator‐based direct flow visualization technique applied to a concentric cylinder cell with the inner cylinder rotating.
Experimental investigation of low reynolds number flows of liquid‐liquid jets
Authors: Koob E. L. , Hill G. A.
Published: March 2009

The shapes of liquid jets issuing from tubes into a second immiscible liquid are examined experimentally. Previous theoretical work is seen to be based on boundary layer theory and therefore not applicable to low Reynolds number jets as presented here. However, these works have provided insight into dimensionless parameters which could be important in governing this process. The experimental data is presented in the form of these dimensionless groups so that their significance can be explored.

The results clearly show that the dispersed phase Reynolds number and the viscosity ratio of the two liquid jets are the most important parameters affecting jet shape. Non‐Newtonian elasticity is seen to contribute to jet expansion but not as much as in the case of inviscid jet swelling. The continuous phase is seen to have a component of velocity far from the jet surface unlike the assumption used in boundary layer theory.

The boundary layer theory of Schlichting was extended to predict jet shapes for a viscosity ratio of one. It is seen that the theory does not apply within 15 dimensionless distances from the tube exit. Accurate predictions will require more precise evaluation of the equations of motion.
Local droplet diameter variation in a stirred tank
Authors: Tanaka Masato
Published: March 2009

The local variation of droplet diameter in a stirred tank was measured in the vicinity of the impeller and at another region. The degree of difference in droplet diameter between regions increases with the impeller speed.

A correlation equation between the local difference in droplet diameter and the frequencies of coalescence and circulation of the droplet was derived according to the circulation interaction model. The degree of local difference in droplet diameter was found to be controlled strongly by the ratio of coalescence to circulation frequency.
Prediction of pressure drop and void‐fraction in annular two‐phase flows
Authors: Kadambi V.
Published: March 2009

The polynomial vvelocity profile due to Pai (1953), applicable to transition and turbulent conditions in single phase flow, has been used to solve the equations of two‐phase annular flow with appropriate matching conditions at the interface and at the boundaries. The results obtained enable one to predict the pressure drop and the void‐fraction, when the interfacial friction factor is specified. Entrainment of the liquid in the core of the flowing gas has been taken into account by using the empirical relation of Hutchinson and Whalley (1973). It has been shown that the theory provides results in agreement with horizontal tube and vertical tube adiabatic flow data, in addition to predicting the liquid film thickness accurately.
Wall sampling in slurry systems
Authors: Nasr‐El‐Din H. , Shook C. A. , Esmail M. N.
Published: March 2009

An 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

A 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

Solutions 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

The 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

A 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

The 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

Reactions 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

The 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

The 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

Mass 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

The 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

Coal 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

The 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

A 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

The 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

The 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.