bluuebunny/crossref_metadata_2025 huggingface dataset:
Continuous measurement of surface and interfacial tension by stationary slug method
Authors: Rao N. V. R. , Baird M. H. I.
Published: March 2009

The surface tensions of various liquids have been measured continuously by controlling their flow so that a slug of air is held stationary in a vertical tube. The dependence between the velocity (expressed as Froude number) and surface tension (expressed as Eotvos number) has been correlated for many low viscosity liquids. An extension of the correlation to viscous liquids has also been proposed and the effect of temperature has been studied.

Due to dynamic surface tension effects, the data for surfactant solutions measured by this continuous method are higher than values found by static (equilibrium) techniques, so the method is not recommended for surfactant solutions.

A slight modification of the apparatus and procedure permits the continuous measurement of interfacial tensions of liquid‐liquid systems, data for which are also presented.
Pressure drop, holdup and interfacial area in vertical two‐phase flow of multi‐jet ejector induced dispersions
Authors: Radhakrishnan V. R. , Mitra A. K.
Published: March 2009

Measurements are reported on pressure drop, holdup and interfacial area in a vertical column where a multi‐liquid jet ejector has been used for gas dispersion. Studies have been carried out in the bubble zone up to the onset of slugging. Correlations in terms of physical and dynamic variables have been developed to predict irreversible loss and holdup in such systems. Extensive statistical analysis showed that the correlations are highly significant at the 99 per cent confidence level. Measurements of interfacial area have been carried out by the chemical method. The measured values of the interfacial area were in the range of 5000 to 25000 m2/m3 in the ejector and 450 to 2650 m2/m3 in the total system. A correlation for predicting interfacial area has also been proposed as a function of the holdup in the system.
Wall‐to‐bed heat transfer coefficient in gas—liquid—solid fluidized beds
Authors: Muroyama K. , Fukuma M. , Yasunishi A.
Published: March 2009

Wall to bed heat transfer has been studied in three‐phase fluidized beds with a cocurrent up‐flow of water and air. Six sizes of glass beads, two sizes of activated carbon beads and one size of alumina beads, varying in average diameter from 0.61 to 6.9 mm and in density from 1330 to 3550 kg/m3, were fluidized in a 95.6 mm diameter brass column heated by a steam jacket. Complementary heat transfer experiments have been performed also for a gas–liquid cocurrent column and liquid–solid fluidized beds.

The wall‐to‐bed coefficient for heat transfer in the gas–liquid–solid fluidized bed is evaluated on the basis of the axial dispersion model concept. The ratio of the wall‐to‐bed heat transfer coefficient in the gas–liquid–solid fluidized bed to that in the liquid–solid fluidized bed operated at the same liquid flow rate is correlated in terms of the ratio of the velocity of gas to that of liquid and the properties of solid particles. A correlation equation for estimating the wall‐to‐bed heat transfer coefficient in the liquid–solid fluidized bed is also developed.
The effect of time on stream and feed composition on the selectivity of a cobalt fischer—Tropsch catalyst
Authors: Sarup B. , Wojciechowski B. W.
Published: March 2009

The Taylor–Wojciechowski formulation of Fischer Tropsch product distributions has been used to study the effect of time on stream and of feed composition on the parameters which arise in the T–W treatment. An experimental setup which allows the required evaluation of product yields is also described.

The T–W formulation was found to give an excellent fit to data obtained using a cobalt‐on‐kieselguhr catalyst. Since the ratios of the various specific rates of parallel synthesis reactions were found to be different functions of the H2/CO ratio in the reactor, we conclude that propagation, branching and termination reactions are not governed by the same kinetics.
Peat adsorption of herbicide 2,4‐D from wastewaters
Authors: Cloutier Jean‐Noël , Leduy Anh , Ramalho Rubens S.
Published: March 2009

The possibility of utilizing peat as adsorbent for removal of the pesticide 2,4‐D from contaminated wastewaters has been evaluated in this investigation.

Batch tests were conducted at different conditions of initial solute concentration, pH, particle size of adsorbent, temperature and ratios of weight of adsorbent to solution volume, in order to determine the optimum range of these variables for the adsorption operation. Removal ratios for the 2,4‐D of the order of 90% were obtained under optimum conditions. The adsorption of 2,4‐D in peat is described adequately by the Freundlich isotherm.

Continuous tests, utilizing adsorption columns, were then conducted in order to determine the design parameters for a proposed treatment plant. The column tests were adequately correlated by the Bohart‐Adams equation.
Stabilisation of emulsion droplets by fine powders
Authors: Levine S. , Sanford E.
Published: March 2009

Finely divided solids can stabilize emulsion droplets provided the solids are partially wetted by both the disperse liquid phase and the continuous liquid phase. The stabilisation of oil/water emulsions by finely divided solids in the presence of suitable organics has been related to the three phase (solid/oil/water) contact line. Schulman and Leja (1954a) and Taubman and Koretskii (1965) provide evidence that O/W emulsions are formed when the contact angle is less than 90° but inversion occurs to W/O emulsions when the contact angle exceeds 90°. We present a thermodynamic study of emulsion stabilization by finely divided solids, which is an extension of an earlier theory by Van der Minne (1928) who neglected interactions among the particles and droplets and also entropy effects due to Brownian motion. Only stable W/O emulsions are considered here. The starting point of the theory is an expression for the Helmholtz free energy associated with the oil/water interfaces stabilized by finely divided solids in the presence of surfactants. By minimising this free energy, it is shown that in a stable emulsion almost all the solid particles are adsorbed at the oil/water interface of the oil drops. This accounts for the experimental result that the average size of oil droplets decreases with increase in the concentration of solids. A particular example of emulsion stabilization by solids occurs in the hot water extraction process on the Athabasca oil sands. Both clay particles and anionic surfactants act as stabilizers of the bitumen droplets suspended in an aqueous alkaline environment.
Wood liquefaction with hydrogen or helium in the presence of iron additives
Authors: Bestue‐Labazuy C. , Soyer N. , Bruneau C. , Brault A.
Published: March 2009

The catalytic activity of several iron additives was studied during the liquefaction of poplar wood suspended in water at 340°C. Iron powder gave good oil yields of ∼40%. The iron seemed to be an effective additive at the beginning of the reaction before being converted into Fe3O4. A systematic study of the influence of the initial pressure and volumetric composition of the gas phase (hydrogen‐helium mixtures) was also made. An initial pressure in the range 4.0‐6.0 MPa was necessary, but the nature of the gas had no significant effect on the yield and the quality of the oils obtained when the percentage amount of iron on dry wood was at least 14%. A stoichiometric equation for the liquefaction reaction is proposed which agrees with experimental results regardless of the initial gas composition.
Flotation of Uranium from uranium ores in Canada: Part II — Cupferron adsorption on uranium oxide, quartz, illite and a uranium ore from elliot lake
Authors: Muthuswami S. V. , Vijayan S. , Woods D. R.
Published: March 2009

Measurements are reported for the equilibrium adsorption of cupferron from solutions by uranium oxide, quartz, illite, a mixture of these three, pitchblende, pyrite and brannerite ore. The cupferron concentration ranged from 1 to 6 g/L, and the pH was 7 and 8. Most isotherms followed the Langmuir model, although Freundlich behaviour was observed for illite and pitchblende. Most adsorption was pH independent except for illite and pitchblende. The adsorption isotherms for a mixture of uranium oxide, quartz and illite in the same proportions as in the naturally occurring ore agreed with the adsorption on the pyrite‐free ore at pH 8 but not pH 7. We attribute the discrepancy to the use of illite as the model clay.

The specific adsorption of cupferron on quartz and illite is lower by a factor of about 50 and 5, respectively, than the adsorption on uranium oxide. Specific adsorption less than 1 mg cupferron per gm of pyrite free ore does not float the mineral. The corresponding equilibrium concentration of cupferron is 0.5 g/L. A qualitative model is given, and the implications of this work for practical operations are presented.
Photocatalytic oxidation of ethane over TiO2
Authors: Daroux M. , Klvana D. , Duran M. , Bideau M.
Published: March 2009

The photocatalytic oxidation of ethane has been studied at room temperature using a specially designed stirred reactor. The effect on the rate of ethane oxidation, of the partial pressure of reactants, the UV light intensity, the amount of catalyst and the residence time has been evaluated. Running the experiments according to a factorial plan permitted to deduce from a limited amount of experimental data the complete kinetic model corresponding to the steady state adsorption mechanism. On the basis of the experimental critical mass of the catalyst (1.5 g), an expression permitting calculation of the critical mass of the catalyst (TiO2) for any type of photocatalytic reactor has been derived.
Direct conversion of synthesis gas to aromatic hydrocarbons: Variation of product distribution with time‐on‐stream
Authors: Varma R. L. , Jothimurugesan K. , Bakhshi N. N. , Mathews J. F. , Ng S. H.
Published: March 2009

The synthesis of hydrocarbons from syngas was studied over a zirconia‐based cobalt‐nickel catalyst (FT catalyst) alone as well as mixed with zeolite HZSM‐5 at 101.3 kPa in a 12.7 mm i.d. down flow reactor. The product distribution was recorded as a function of time‐on‐stream for several days of continuous operation under fixed operating conditions of 250°C and H2/CO = 1. For the FT + HZSM‐5 system, a dramatic variation in the product distribution takes place during the first 24 h of operation. A comparison of time‐on‐stream results obtained using FT catalyst alone and mixed with HZSM‐5 suggests that the reactions leading to the build‐up of overall product distribution are slower over HZSM‐5 compared to those taking place over FT catalyst. These differences have been attributed to the different nature of reactions taking place over the two components of the mixed catalyst system. Analyses of the coke on the deactivated catalysts are also reported.
Improvement of separation efficiency in the continuous‐type horizontal thermal diffusion column with permeable barriers between the plates
Authors: Yeh Ho‐Ming , Tsai Shau‐Wei , Chen Wen‐Hon
Published: March 2009

The separation theory of the continuous‐type horizontal thermal diffusion column with permeable barriers has been developed by the orthogonal expansion method. Considerable improvement is obtained when the reflux rate and barrier positions are carefully chosen. The idea and mathematical formulism may also be extended to other conjugated Graetz problems with countercurrent flow and refluxes at the ends.
Cracking properties of some reforming catalysts
Authors: Al‐Madfai Suham , Abbas Abdullah A. , Ali Ahmed J.
Published: March 2009

The cracking properties of industrial reforming catalysts of γ‐alumina loaded with 0.6% Pt, with 0.35% Pt, and with 0.35% Pt plus promoters were investigated. The mode of cracking of these catalysts was studied after treatment under different oxidation and reducing atmospheres. Cumene cracking was used as a model reaction. The cracking products were collected and analysed, and the quantity of benzene produced was used to compare the activities of these catalysts. Maximum cracking was observed around 550°C for all catalysts studied. Cracking rates differed for various treatment conditions for the same catalyst, normally increasing after oxidation treatment. Marked changes in the cracking activity of unloaded γ‐alumina were observed after it was chlorinated. Benzene yield was studied in relation to possible complex formation of Pt‐Al2O3‐Cl2.
Retorting of oil shale from new brunswick, canada
Authors: Salib P. F. , Barua S. K. , Furimsky E.
Published: March 2009

Two oil shale samples from the Albert formation in the Moncton Sub‐basin, New Brunswick have been retorted in direct and indirect modes in a pilot scale moving bed retort. The maximum oil recoveries were 81% and 89% of the Fischer assay for direct and indirect mode retorting, respectively. Shale grade, bed height, retort temperature profile, recycle gas and its distribution, and air feed rate affected the oil recovery. The spent shale retained approximately 30% of the energy content of the fresh shale.
Fractionnement de deux bois tropicaux (eucalyptus et wapa) par traitement thermomécanique en phase aqueuse. Partie II: Caractéristiques chimiques des résidus et considérations cinétiques sur la solubilisation des hémicelluloses
Authors: Carrasco F. , Chornet E. , Overend R. P. , Heitz M.
Published: March 2009

Nous avons caractérisé par voie chimique les résidus solides issus de la liquéfaction par fractionnement en milieu aqueux de deux essences tropicales. Le procédé de fractionnement est constitué des étapes suivantes: préparation de la suspension aqueuse, préchauffage à 135°C, décharge à travers une restriction (ΔP = 17,2 MPa), réaction entre 180 et 230°C, puis refroidissement rapide.

Les solides résiduels ont été analysés selon les deux méthodes suivantes:

hydrolyse acide: cette technique permet de quantifier les monosaccharides présents dans le résidu et de suivre ainsi la solubilisation des hémicelluloses et de la cellulose.

analyse élémentaire: cette technique s'est révélée ětre un indice de la solubilisation connexe des hémicelluloses et de la lignine.

Par chromatographie gazeuse nous avons détecté le CO2 comme étant le seul gaz formé à des températures inférieures à 230°C.

Deux modèles cinétiques de premier ordre relatifs à la solubilisation des hémicelluloses et à la formation du dioxyde de carbone ont été développés et appliqués aux résultats expérimentaux.
Statistical analysis of the removal of aluminum and magnesium impurities from wet‐process phosphoric acid
Authors: Feki M. , Chaabouni M. , Ayedi H. F. , Heughebaert J. C. , Vaillant M.
Published: March 2009

The present paper relates to the treatment of crude wet‐process phosphoric acid with ammonium nitrate and hydrofluoric acid to precipitate aluminum and magnesium impurities in the form of an easily separable phase: (NH4)xMgyAlz(F, OH)6.2 H2O. To check the effect of some concentration factors on this reaction, an orthogonal central composite design is realized with three variables: %Al3+, %NH4+and %F−. It is concluded that the amount of aluminum in acid is the limiting factor of magnesium precipitation. Thus complete removal of magnesium, which is a major impurity in wet‐process phosphoric acid, can be obtained by adding to the crude acid extra soluble aluminum salt simultaneously with hydrofluoric acid and ammonium nitrate.
The computer‐derivation of thermodynamic equationspart II. first and second derivatives for complex unrestricted systems
Authors: Farah N. , Missen R. W.
Published: March 2009

An algorithm, based on Jacobians and implemented on a microcomputer (IBM PC), is described for the derivation of expressions for first and second thermodynamic derivatives for complex systems, unrestricted, however, by (chemical) equilibrium constraints. The work has progressed through the design of two separate algorithms implemented by symbolic manipulation software. First, a thermodynamic derivation system, THERMODER1, was developed, aided by a symbolic mathematical system (muMATH‐83tm), together with its language of implementation (muSIMP), and certain user‐defined functions. THERMODER1 is capable of deriving expressions for first and second thermodynamic derivatives for simple systems (2 degrees of freedom, unrestricted). A second algorithm, THERMODER2, also implemented by the symbolic mathematical system, has been developed for both simple and complex (unrestricted) systems. THERMODER1 has been described previously, and THERMODER2 is described here. These algorithms are intended to be extended ultimately to chemical systems subject to equilibrium constraints. Examples, using THERMODER2, are given.
Effect of soluble ash components on the viscosity of lignite‐water mixtures
Authors: Sadler L. Y. , Bethany B. A.
Published: March 2009

The removal of multivalent cations from lignite‐water mixtures (LWM) was shown to lower mixture apparent viscosity by a factor of about 40, for example, at 100 s−1 by reducing both the yield stress and plastic viscosity. The cations Ca++, Mg++, Al+++, K+, and Na+, among others, were found to be present in the aqueous phase of the LWM in concentrations ranging from 546 ppm to 8 ppm. The primary anions present were CI− and SO4=. The degree to which the cations affected viscosity were of order trivalent > divalent > monovalent. The nature of the anion was found to be relatively unimportant. A process utilizing ion‐exchange resins for removing multivalent cations to produce low viscosity lignite‐water or coal‐water mixtures is described.
Spatial control of sheet and film forming processes
Authors: Bergh Luis G. , Macgregor John F.
Published: March 2009

The general problem of controlling both machine and cross‐directional properties on sheet and film forming processes is treated. A flexible class of linear dynamic‐stochastic models capable of characterizing the process and disturbance dynamics in these systems is suggested. Procedures are presented for identifying these models from data collected from common scanning type sensors. Linear‐Quadratic‐Gaussian (LQG) control theory is used to design multivariable controllers capable of jointly controlling the machine and cross‐directional property variations using both lumped and spatially distributed actuators.
Hydrogenation of cyclohexene and benzene over an amorphous pd‐zr alloy
Authors: Takahashi Takeshige , Nishi Yoshinori , Otsuji Nobuyuki , Kai Takami , Masumoto Takeshi , Kimura Hisamichi
Published: March 2009

Amorphous Pd‐Zr alloys, produced by a rapid solidification technique, were studied to determine their catalytic activity for the hydrogenation of cyclohexene and benzene. The activity of the amorphous alloy without pretreatment by air was lower than that of the corresponding crystalline alloy, but it was gradually increased with the pretreatment. The surface area and the hydrogen adsorption activity of the alloys were simultaneously increased with the pretreatment. It is found from X‐ray diffraction pattern and SEM observation that palladium, which is an active species for hydrogenation in the amorphous alloys, is highly dispersed on the granulated ZrO2 surface by the pretreatment.
Drainage in thin planar non‐newtonian fluid films
Authors: Hartland Stanley , Jeelani A. K.
Published: March 2009

Equations for the radial and linear drainage of non‐Newtonian fluids in horizontal and inclined films are presented. For a power law fluid with index m, the variation in dimensionless film thickness Δ with dimensionless time T is given by:

where Δ and T are appropriately defined for drainage in radial horizontal and linear inclined films. The corresponding approximate expression for a Bingham plastic fluid is:

in which A is the minimum film thickness defined appropriately at the asymptotic limits when Δ » A and Δ ⋍ A.
Investigations of fluid dynamics in mechanically stirred aerated slurry reactors
Authors: Wong C. W. , Wang J. P. , Huang S. T.
Published: March 2009

The fluid dynamics of stirred aerated slurry reactors with A‐310® propeller, 4‐blade 45° pitch turbine and 6‐blade Rushton disc turbine were studied over a wide range of gas flow rates. With respect to power consumption, gas hold‐up, and fluid dynamically limiting cases, viz., suspension and flooding, the Rushton disc turbine was found to be the best in stirred aerated slurry reactors. The influence of particle density, shape and mass fraction and of liquid properties on gassed critical stirrer speed, Njsg, and of gassed power input per unit volume, Pjsg, on particle suspension and gas dispersion, were investigated. Empircal correlations in combination with that of Zwietering were established for scale‐up design in three‐phase slurry reactors.
Ablation of ice‐solids and wax‐solids mixtures in turbulent axisymmetric water jets
Authors: Law Hin‐Sum , Masliyah Jacob H. , Nandakumar K.
Published: March 2009

The ablation rate of frozen mixtures of water or wax with finely divided solids subjected to a turbulent axisymmetric water jet was investigated both experimentally and theoretically. The range of the water jet Reynolds number was 8700–29300 and the jet temperature varied between 22 and 60°C. The solids used were very fine kaolinite clay, titanium oxide and aluminium powder.

The type of solids and their concentration were found to affect the ablation rate of ice‐solids and wax‐solids mixtures. This is mainly due to changes in the physical properties of the melt layer of the water‐solids or wax‐solids mixtures which forms between the impinging jet and the frozen mixtures.
Remarks on random residence time distributions
Authors: Iordache Octavian , Corbu Sergiu
Published: March 2009

A discrete stochastic mixing model for chemical reactor; is presented here. The turbulent flow system has been modeled as a network of ideally mixed compartments with interconnecting flows that are random variables.

The model is particularly useful for studying the statistics of RTD and of the output concentration in a chemical reactor. Some computations of confidence intervals of concentration using information about the stochastic nature of flows are presented.
An application of MACSYMA in solving the laminar flow of micropolar fluid in a meandering channel
Authors: Easwaran C. , Majumdar S. R.
Published: March 2009

Plane laminar micropolar fluid flow in a meandering channel of constant width is considered. A perturbation scheme based on the assumption of slow and slight curvature of the centreline is used to study the effect of curvature and various micropolar parameters on some flow properties. The symbol manipulation system MACSYMA is used to generate the successive perturbation equations. The effects of two different types of boundary conditions are investigated. The second approximation is given for a general centreline geometry. Results indicate that to the order of approximation considered, pressure gradient along the centreline is increased while shear stress on the walls is decreased for micropolar fluids and the effect of curvature becomes more pronounced with increasing micropolarity.
Modeling of the free flight region of a cyclone transferred arc plasma reactor
Authors: Chen L. S. , Munz R. J.
Published: March 2009

The Plasmacan cyclone transferred arc plasma furnace seems ideally suited for the treatment of fine refractory powders to produce a consolidated liquid product. In this furnace, particles are pneumatically injected tangentially near the wall of a cylindrical sleeve while an arc is struck along the central axis of the sleeve. A simple model has been developed to examine the behaviour of the injected particles in the entrance region of the furnace up to the point where the particles reach their melting point and form the molten film. Three‐dimensional equations of particle motion are solved to compute particle trajectories, given gas temperature and velocity fields in the furnace. The location of the first appearance of the molten film is computed under a variety of operating conditions for a laboratory scale furnace.
Liquid phase synthesis of methyl tert‐butyl ether catalyzed by ion exchange resin
Authors: Subramaniam C. , Bhatia S.
Published: March 2009

Synthesis of methyl tertiary butyl ether (MTBE) from methanol and isobutene was studied using macroporous cation exchange resin, Amberlyst 15 in the hydrogen form, as a catalyst in the temperature range of 313‐328 K. The reaction was carried out in a batch reactor at a pressure of one atmosphere in the liquid phase. A high degree of agitation was maintained in order to eliminate film diffusion resistance. The effect of catalyst loading, catalyst particle size and reaction temperature on reaction rate were studied. The reaction rate increased with increase in catalyst concentration and reaction temperature. Resin particle size had virtually no effect on the rate under the experimental conditions.

The reaction rate data were analysed using homogeneous kinetics and heterogeneous models based upon Langmuir‐Hinshelwood rate expressions. The apparent activation energies using homogeneous and heterogeneous models were determined and found as 79.0 kJ/mol and 76.7 kJ/mol respectively.
Performance of a large scale packed recirculating reactor for homogeneous catalytic oxidation of car‐3‐ene
Authors: Mukesh D. , Gopalkrishnan K. S.
Published: March 2009

Autooxidation of car‐3‐ene was carried out in a large scale packed recirculating reactor, where the catalyst cobalt acetylacetonate and the liquid were recirculated and sprayed on top of an inert packing. Gas is introduced from the bottom. The mass transfer parameters and mixing characteristics of the reactor were determined. The effect of catalyst quantity, operating pressure on car‐3‐ene conversion, and selectivity for various products were studied. The reaction system was mathematically modelled, and the simulation compared with the observed behaviour. The rate constants of the elementary reaction steps had been determined separately in a laboratory reactor.
The surface renewal model of wall turbulence for boundary layer flow with transpiration
Authors: Thomas L. C. , Loughlin K. F.
Published: March 2009

The object of this paper is to develop and evaluate the basic surface renewal modeling approach for transpired turbulent boundary layer flows. Using a simple form of the surface renewal model in conjunction with the standard mixing length representation of the turbulent core, calculations are established for the dimensionless burst frequency s+, and distributions in velocity u+ within the inner region as a function of transpiration rate v+ and pressure gradient P+.
Initial fouling of nontoxic coatings in fresh, brackish, and sea water
Authors: Meyer A. E. , Baier R. E. , King R. W.
Published: March 2009

Objectives of this project were to evaluate benefits — over the short term — that might derive from control of the surface properties of materials used in energy transfer devices; and to identify preferred ranges of surface parameters that might be specified to minimize deposits of biological fouling known to deteriorate energy exchange efficiencies in seawater, brackish water, and freshwater systems. By modifying the surface chemistry and surface energy of test plates with very thin coatings (nontoxic) and examining the acquired films at various time intervals, the earliest events of biofouling caused by macromolecules and microbial organisms were defined. Overall, the results were remarkably similar for all systems tested in showing that deliberate modification of the initial material surface qualities can significantly reduce the retention of biofouling layers.
On the examination of recycle on heat (and mass) transfer in concentric tubes
Authors: Yeh Ho‐Ming , Tsai Shau‐Wei , Hsiey Mean‐Chu
Published: March 2009

The effect of recycle on heat (and mass) transfer in concentric circular tubes has been investigated by finite difference methods. Theoretical results show that recycle can enhance the heat transfer rate for large Graetz numbers compared with that in an open tube (without an inner tube inserted and without recycle). Competition between a preheating effect and a residence‐time effect can be used to explain the heat transfer behavior. The heat transfer rate can be further augmented, with nearly no increase in total pressure drop, by employing flow pattern B instead of flow pattern A.
Moment analysis of nonlinear systems: A kinetic study
Authors: Hwang Bing Joe , Chou Tse‐Chuan
Published: March 2009

The moment method has been used extensively to evaluate parameters of chemical reactions, adsorption or reactor design, but only for linear systems. Moment analysis of nonlinear systems is studied in the present work. A general complicated reaction system involving nonlinear terms in a batch slurry reactor is chosen to demonstrate the method. The first and second improved solutions in Laplace domain and moment expressions are obtained. The improved solution can converge to the exact solution if the iterative procedures are repeated several times.
The importance of temperature rise time in pyrolysis kinetic studies
Authors: Rastogi Ashutosh , Svrcek William Y. , Behie Leo A.
Published: March 2009

The measurement of the kinetics of fast chemical reactions, such as hydrocarbon pyrolysis, is often hampered by limitations of the experimental reactor. To overcome problems in getting to reaction temperature, a micro‐reactor system has been developed with temperature rise times (TRT) in the millisecond range. Data is presented for the dynamic response of a Curie Point pyrolyser along with a computer simulation of how the gas‐filled micro‐reactor would respond. The importance of temperature rise time is clearly demonstrated by the computer simulations of propane and naphtha pyrolysis in the temperature range of 600°C and 1100°C.
High pressure phase equilibria in the carbon dioxide ‐ n‐Hexadecane and carbon dioxide — water systems
Authors: D'souza Rupert , Patrick Jennie R. , Teja Amyn S.
Published: March 2009

Phase equilibria in the carbon dioxide ‐ n‐hexadecane and carbon dioxide – water systems have been measured at temperatures between 314 K and 353 K and pressures between 8.53 and 16.12 MPa. The results have been correlated using two cubic equations of state and also compared with measurements reported in the literature.
Viscosities of binary liquid mixtures of cyclohexanone with alkanes, benzene, toluene and tetrachloromethane at 298.15 K
Authors: Rao K. Purna Chandra , Reddy K. S.
Published: March 2009

Viscosities for the binary liquid mixtures of cyclohexanone with n‐hexane, n‐heptane, 2, 2, 4‐trimethylpentane, benzene, toluene and tetrachloromethane have been determined at 298.15 K. The deviation in viscosity from the ideal law is negative in all the systems except in the system, cyclohexanone with tetrachloromethane. In this system excess viscosity exhibits a positive deviation over the entire range of mole fraction. The results have been interpreted in terms of molecular interactions, and of difference in size and shape of components. The theoretical excess viscosities have been calculated from absolute reaction rate theory and free volume theory of flow by making use of the Bloomfield and Dewan relations. Theoretical excess viscosities are in qualitative agreement with experimental results for four out of the six systems examined.
End wall effects on thermal stratification and heat transfer in a vertical enclosure with offset partitions
Authors: Jetli R. , Acharya S.
Published: March 2009

End wall effects on thermal stratification and heat transfer in a vertical enclosure with offset partitions has been studied by numerically solving the governing differential equations. Two limiting end wall conditions are investigated — adiabatic end walls and perfectly conducting end walls. Two offset partition positions and three partition heights are considered. It is observed that with adiabatic end walls, the heat transfer from the vertical hot and cold walls is always greater. The effect of end wall conditions is most significant when the top partition is offset toward the cold wall and the bottom partition toward the hot wall. In this position strong thermal stratification in the core is observed. When the direction of offset is reversed, i.e., top partition is moved closer to the hot wall and the bottom partition closer to the cold wall, strong stratification effects are noted in the partition‐near side wall region. Adiabatic end wall conditions promote these stratification effects.
Gas absorption with exothermic bimolecular reaction in a thin liquid film: Fast reactions
Authors: Bhattacharya A. , Gholap R. V. , Chaudhari R. V.
Published: March 2009

A problem of gas absorption with a fast nonisothermal bimolecular reaction in a thin liquid film has been analysed. Approximate analytical solutions for the interfacial temperature rise and enhancement factor have been derived incorporating the influence of depletion of liquid reactant concentration at the interface. The effects of heat generation, heat dissipation and reaction rate parameters on enhancement factor and interfacial temperature rise have been discussed. For a certain range of parameters, multiple steady state solutions of enhancement factor and interfacial temperature rise are observed. Another interesting observation is that as the value of a dimensionless parameter ϕ increases, the enhancement factor approaches its instantaneous asymptote which is the same as that for the isothermal case in an instantaneous regime. The analysis presented here is simple and avoids complex numerical computations and it is likely to be useful in design applications.
Isobaric vapor‐liquid equilibrium and liquid‐phase enthalpy of mixing data for the binary mixtures of m‐ or p‐Xylene with cyclohexanol
Authors: Comelli Fabio , Francesconi Romolo , Arcelli Antonio
Published: March 2009

Isobaric vapor‐liquid equilibrium data and liquid‐phase enthalpy of mixing are investigated for the binary mixtures of m‐ or p‐xylene with cyclohexanol. Allowance for self‐association of the cyclic alcohol is made when assessing the thermodynamic consistency of the experimental data.

Activity coefficients are correlated to mole fractions through the Wilson Equation, the parameters of which are obtained by the method of maximum likelihood and compared with the ones given by the conventional unweighted least‐squares procedure.
Ethylene recovery from low grade gas stream by adsorption on zeolites and controlled desorption
Authors: Mao Raymond Le Van , Mclaughlin Gerald P.
Published: March 2009

Carbon dioxide was partially removed from a nitrogen stream, which also contained some ethylene, by adsorption on a 4A (Na‐A) zeolite. The treated nitrogen stream was then passed over a 13X (Na‐X) zeolite bed upon which ethylene and any remaining carbon dioxide were adsorbed. Ethylene was recovered by desorption at 68 Pa pressure into a slow flow of nitrogen as stripping gas. The ethylene concentration in the extracted gas was extremely dependent on the nitrogen flow‐rate, whereas the concentration of carbon dioxide remained practically constant. Thus, it was possible to obtain a gas mixture greatly enriched in ethylene with a reasonably low content of carbon dioxide.
Rheological properties of polymer‐added lubricating oils
Authors: Derdouri A. , Ait‐Kadi A. , Carreau P. J.
Published: March 2009

Rheological measurements of polyisobutylene solutions are presented. A mineral oil of low viscosity has been used as solvent. The combined effects of concentration, molecular weight and temperature were studied. It is found that the rheological data, when plotted as N1λE/(η‐ηs) versus λEγ fall on a master curve over several decades of the dimensionless shear rate, irrespective of temperature, polymer concentration and molecular weight. The findings of this work can be used to address the problem of hydrodynamic lubrication of a journal bearing using a viscoelastic lubricant.
Dissolved oxygen removal by combination with hydrogen using wetproofed catalysts
Authors: Suppiah S. , Kutchcoskie K. J. , Balakrishnan P. V. , Chuang K. T.
Published: March 2009

Dissolved oxygen in water at parts per million levels could be reduced to a few parts per billion by reaction with hydrogen using Pt catalysts supported on carbon and stainless steel in random and structured bed configurations. The carbon supported catalyst was Teflon coated to wetproof it. Both gas phase and liquid phase reactions occurred simultaneously under trickle bed operation, resulting in higher oxygen removal efficiency for this mode of operation than for the liquid‐filled condition. The structured catalyst bed yielded greater hydraulic capacity than the random bed, and with wetproofed catalyst it gave the best oxygen removal efficiency. Since the gas phase reaction rate could be increased by reducing the wetted fraction of the catalyst through wetproofing, wetproofed catalysts offer a unique advantage over conventional hydrophilic catalysts.
Vapor liquid equilibrium data for alcohol n‐Amylamine binary systems at 333.15 K. Reduction of the experimental data by a novel model‐free method
Authors: Abusleme J. A. , Vera J. H.
Published: March 2009

Vapor liquid equilibrium measurements for the binary systems of n‐amylamine with methanol, ethanol and 1‐propanol at 333.15 K are reported. The measurements were made in a static equilibrium cell of the Van Ness type and the experimental data were reduced using a model‐free method. This model‐free method is an adaptation of the method of Mixon et al. in which a material balance is introduced to correct for the mols of the gas phase. Second virial coefficients of n‐amylamine and cross second virial coefficients for the binary systems were measured in this work and parameters for the Tsonoupolos correlation are reported.
Equilibrium characteristics for the extraction of cobalt and nickel into di(2‐ethylhexyl) phosphoric acid
Authors: Golding J. A. , Barclay C. D.
Published: March 2009

The liquid‐liquid extraction of cobalt and nickel from aqueous sulphate solutions into di(2‐ethylhexyl) phosphoric acid, DZEHPA, has been investigated at 25°C and 60°C. The system studied was made up as follows: the aqueous phase‐cobalt and nickel dphates; the organic phase‐20% D2EHPA, 75% Esso solvent DX3641 and 5% tri‐butyl phosphate. Analogies to vapour‐liquid equilibria were made to develop three methods to correlate the binary equilibrium data, namely: 1) a delta Y method, 2) a method based on the correlation of solvent free mole fractions in both phases and 3) a “pseudo activity” coefficient or pseudo gamma method, γAB.

The methods were evaluated as to their suitability for the prediction of binary isotherms. The delta Y and pseudo gamma methods were found to give the best results.
A study of CrO vapor decomposition in approximated isothermal RF plasma reactors
Authors: Meubus P. , Huczko A.
Published: March 2009

A simplified RF plasma reaction model has been used for describing the thermal decomposition reaction of chromium oxide (CrO), using an argon RF plasma operated at 2.7 kW. A set of 3 approximated isothermal reactors in series were defined for this purpose within the RF torch. The conversion rate curves were obtained for the respective average isothermal temperatures 4250 K, 3500 K and 2950 K. Reaction order and reaction rate constant were determined at each temperature.

Based on the values obtained for the reaction orders, it appears that the kinetics process involved is similar at 2950 K and 3500 K, while a distinctly different process occurs at 4250 K. Assuming that the two former reactions show an Arrhenius type behavior, an activation energy value has been derived, valid between 2900 K and 3500 K.

The activation energy for the CrO decomposition reaction has been calculated on the basis of an Eyring and Polanyi model. The calculated and experimental results differ by about 20%. The main point responsible for the large reaction rate constant increase observed at 4250 K is the drastic change of the pre‐exponential factor in the Arrhenius equation.
Propenoxide isomerization in a fluidized bed reactor
Authors: Danciu Emil , Straja Sorin
Published: March 2009

Propenoxide isomerization, over lithium orthophosphate as a catalyst, was investigated in a fluidized bed reactor. A mathematical model of the process was developed and its kinetic parameters identified. There is a high degree of selectivity for allyl alcohol.
Rey‐zeolite and silica‐alumina mixed support for hydrotreating heavy gas oil
Authors: Sambi Inderjit S. , Mann Ranveer S.
Published: March 2009

Rare earth exchangedY‐type zeolite (REY‐zeolite) was dispersed in a silica‐alumina gel to prepare catalyst supports with better hydrogenolysis activity. Such support material showed improved hydrotreating properties compared to commercial catalysts, especially for heavy gas oils. Statistical experimental designs used to optimize the composition of such mixed supports suggested a composition of 10 wt.% silica, 25 wt.% zeolite and 65 wt.% alumina as optimum for hydrotreating a heavy gas oil (343°C to 525°C fraction) obtained from hydrocracking of Athabasca bitumen. The kinetic parameters were then evolved for the optimum catalyst.
Sequential statistical design strategy in a kinetic study of propylene oxidation
Authors: Tan H. S. , Bacon D. W. , Downie J.
Published: March 2009

A sequential design strategy was used to direct an experimental kinetic study of propylene oxidation over bismuth molybdate. Two statistical criteria were used to design experiments. The first is a joint criterion for the dual problem of model discrimination and parameter estimation which was proposed by Hill et al. (1968), but which to the best of our knowledge has not been tested in an experimental program. Using this joint criterion design, it was demonstrated that both the objectives of model discrimination and precise parameter estimation were effectively accomplished. After model discrimination had been achieved, a design strategy for further improvement in parameter precision was found, as expected, to be effective for that purpose.
Maximizing the capacity and life of depth‐type filters
Authors: Dullien F. A. L.
Published: March 2009

An analytical expression has been derived for the variation of the filtration coefficient of depth‐type filters with fractional depth from the downstream to the upstream face of the medium which satisfies the condition of identical retention in every cross‐section of the medium. A numerical example has been worked out for a fibrous filter where the porosity of the medium was varied to comply with the required variation of the filtration coefficient. It has been shown also that a filter consisting of three uniform layers of different porosities may adequately approximate the required continuous variation of the filtration coefficient. After a retention of 10% pore volume of dust the permeability of the three‐layer medium is about 4 times greater than that of a medium of uniform initial porosity characterized by identical initial collection efficiency, thickness and fiber diameter.
La modélisation de la turbulence dans une enceinte avec ouvertures et sources chaudes localisées
Authors: Dupuis Marc , Dernedde Edgar , Methot Jean‐Claude
Published: March 2009

La circulation de l'air dans une enceinte avec plusieurs ouvertures et sources chaudes localisées a été étudiée à l'aide d'un modèle mathématique. Après plusieurs comparaisons avec les circulations observées dans une maquette, on a constaté qu'un modèle de turbulence devait ětre introduit pour améliorer la simulation mathématique. Deux modèles de turbulence, basés sur le modèle algébrique et sur le modèle différentiel (K‐ϵ‐G) de la viscosité turbulente, ont fait l'objet d'investigations. Le modèle différentiel a apporté peu d'amélioration aux résultats et a augmenté de beaucoup le coüt d'opération par rapport au modèle algébrique. L'utilisation du modèle différentiel n'était donc pas justifiée pour ces simulations.

L'effet combiné de la convection forcée à travers l'enceinte et de la convection naturelle au voisinage des sources chaudes, a été simulé dans le but d'étudier la circulation de l'air et de la température dans une salle de cuves d'électrolyse de l'aluminium.
Analysis of several methods to determine the activity of water in solutions of strong electrolytes
Authors: Correa H. A. , Vega R. E.
Published: March 2009

The methods of Zdanovskii‐Stokes‐Robinson (ZSR), Reilly‐Wood‐Robinson (RWR), Pitzer and Correa, to determine water activity in ternary solutions of electrolytes from data for water activity in binary solutions, were analysed. In addition, the first two methods were used to estimate the activity of water in supersaturated binary solutions using data from ternary solutions. Also, the equation of Correa for binary solutions was extrapolated to calculate the activity of water at supersaturation.

The methods were tested using the experimental data (at 25°C) for nine ternary systems, with a common ion, involving the following ions: Li+, Na+, K+, Ca++, Mg++, Cl− and NO3−. Zdanovskii's method gave the best estimations of water activity in ternary systems. The method of Correa gave smaller standard deviations than the methods of Pitzer and RWR with the advantage that its application is simpler. For binary solutions at supersaturation, Correa's method gave better results than the method of ZSR and this, in turn, yielded smaller deviations than the RWR method.
Self oscillation phenomena of turbulent jets in a channel
Authors: Murai Kazuhiro , Kawashima Yosuke , Nakanishi Shigeyasu , Taga Masao
Published: March 2009

A new method based on the Coanda effect for self oscillation of a circular jet bounded by rectangular enclosure is suggested. The experiments in both air and water reveal regions of stable oscillation wherein relationships are obtained between the Strouhal number and the shape factor of the channel.

This oscillation method can also be used to mix different liquids in a vessel. For such applications, an improvement of mixing by oscillation is shown by means of a residual concentration diagram for a salt solution.
Oxidation kinetics of anthracene with nitrogen dioxide in acetic acid
Authors: Rodriguez F. , Tijero J. F.
Published: March 2009

Kinetics of liquid‐phase oxidation of anthracene to anthraquinone with nitrogen dioxide in acetic acid as solvent has been studied. The reaction takes place through the anthrone as intermediate compound. The first and second reactions are first order with respect to anthracene and anthrone concentration, respectively. The values of the rate constants in the temperature range 60–95°C have been reported.

According to the reaction system developed, an industrial process for the manufacture of anthraquinone of high purity has been proposed.
Catalytic hydrogenation of carbon monoxide to alkenes over partially degraded iron‐cobalt complexes
Authors: Snel R.
Published: March 2009

Complex‐derived iron–cobalt alloy catalysts have been studied under conditions similar to those normally prevailing in industry. Despite reports in the literature indicating unusual selectivities with iron–cobalt alloy catalysts under atmospheric pressure conditions, no deviations from normal selectivity behaviour have been observed when studied under steady‐state conditions and pressures of 2.0 MPa. However, when promoted with manganous oxide or supported on silica‐alumina, substantial deviations from Anderson‐Schulz‐Flory statistics occur during the first few days on stream. These deviations gradually disappear with increasing time on stream leading to normal selectivity behaviour.

The unsupported catalysts displayed remarkably high activity and selectivity maintenance, in contrast to supported catalysts, which show substantial oscillations in the catalytic behaviour.
An analysis of laminar forced convection film boiling
Authors: Rajagopalan Vijay , Subramanian V.
Published: March 2009

A study of forced convection film boiling on a horizontal isothermal plate is made using a treatment based on boundary layer theory. For the vapour, the velocity and temperature distributions are obtained from equations of motion and energy. For the liquid layer, the Howarth approximation for flow over a plate is used. Then, by employing interface matching conditions, the significance of the rhμ ratio between the vapour and the liquid on the variation of Nusselt number is examined.