bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanostructuring of diamond films using self-assembled nanoparticles
Authors: Babchenko Oleg , Kromka Alexander , Hruska Karel , Michalka Miroslav , Potmesil Jiri , Vanecek Milan
Published: March 2009

We report the use of gold, nickel and diamond nanoparticles as a masking material for realization of diamond nano-structures by applying the dry plasma etching process. Applying low power plasma (100 W) in a gas mixture of CF4/O2 for 5 minutes results in a formation of three different types of diamond nanostructures, depending on the mask type material and particle size. Using of the Ni mask results in realization of diamond nano-rods, applying of the Au mask brings cauliflower-like structures, and using the diamond powder allows the production of irregular nano-structures. The main advance of the presented etching procedure is use of a self-assembly strategy where no lithographic steps are implemented.
Point-by-point inscription of 250-nm-period structure in bulk fused silica by tightly-focused femtosecond UV pulses: experiment and numerical modeling
Authors: Nikogosyan David , Dubov Mykhaylo , Schmitz Holger , Mezentsev Vladimir , Bennion Ian , Bolger Padraig , Zayats Anatoly
Published: March 2009

By conducting point-by-point inscription in a continuously moving slab of a pure fused silica at the optimal depth (170 μm depth below the surface), we have fabricated a 250-nm-period nanostructure with 30 nJ, 300 fs, 1 kHz pulses from frequency-tripled Ti:sapphire laser. This is the smallest value for the inscribed period yet reported, and has been achieved with radical improvement in the quality of the inscribed nanostructures in comparison with previous reports. The performed numerical modeling confirms the obtained experimental results.
Introductory: The Global Potential of Pragmatism
Authors: Višňovský Emil
Published: March 2009

Introductory: The Global Potential of Pragmatism
Pragmatism, Experience, and the Given
Authors: Aikin Scott
Published: March 2009

Pragmatism, Experience, and the Given

The doctrine of the Given is that subjects have direct non-inferential awareness of content of their experiences and apprehensions, and that some of a subject's beliefs are justified on the basis of that subject's awareness of her experiences and apprehensions. Pragmatist criticisms of the Given as a myth are shown here not only to be inadequate but to presuppose the Given. A model for a pragmatist account of the Given is then provided in terms of refinements of Dewey's theory of experience. The doctrine of the Given is implicated in the functions of inquiry insofar as one must take it that experience is a source of justification.
After Ontotheology: Reciprocal, Caring, Creative, and Right Relationships
Authors: Garrison Jim
Published: March 2009

After Ontotheology: Reciprocal, Caring, Creative, and Right Relationships

With the end of ontotheology we may realize, as Dewey did, that what sustains us is our caring relationships with physical nature, biological life, and other persons. My paper argues that relationships are ontologically basic and caring relations are morally basic. Right relationship binds us to the world and holds us together. We live by the grace of others. I conclude that after ontotheology, we must seek to form reciprocal, caring, and creative relationships.
Moral Perfectionism: Ethical Theory from a Pragmatic Approach
Authors: Mougán Carlos
Published: March 2009

Moral Perfectionism: Ethical Theory from a Pragmatic Approach

This article tries to rescue the perfectionist approach to moral theory from the pragmatic tradition and inspiration. Based on the philosophy of Dewey and taking into account authors like H. Putnam or S. Cavell, it tries to defend the idea that pragmatism allows us to understand moral perfectionism in a new way. In that way, perfectionism is bound to a certain interpretation of practical rationality, and a new understanding of moral objectivity and human subjectivity. Finally, moral perfectionism is not a theory that aims to solve all moral dilemmas but provides an understanding of how to face up to the problems of ordinary moral life.
Rorty on Politics, Culture, and Philosophy: A Defence of his Romanticism
Authors: Nyírő Miklós
Published: March 2009

Rorty on Politics, Culture, and Philosophy: A Defence of his Romanticism

Rorty's historicist romanticism is a peculiar and oft criticized feature of his neopragmatism. I attempt to show that it should be regarded not so much as a more or less exceptionable philosophical approach, but rather, as a practice in ‘cultural politics’—which is his ultimate definition for philosophy—prompted by his acute political concerns and his views on the nature of moral progress.
Neopragmatism and the Question of Interdisciplinarity: The Case of Stanley Fish
Authors: Małecki Wojciech
Published: March 2009

Neopragmatism and the Question of Interdisciplinarity: The Case of Stanley Fish

The aim of the paper is to criticize Stanley Fish's views on interdisciplinarity (particularly as far as his account of interdisciplinarity in literary studies is concerned). The first part of the article consists of: (a) a summary of his critique of the so-called religion of interdisciplinarity; (b) a description of Fish's theory of disciplinarity that underlies this critique. In the second part of the article, I provide a criticism of Fish's theory. I begin by presenting some counterexamples to it. Then I attempt to demonstrate that Fish's views are self-refuting. Finally, I argue that besides these theoretical reasons, there is also a practical reason why Fish's position needs to be questioned.
A Recent Guide to the Study of Pragmatism
Authors: Pihlström Sami
Published: March 2009

A Recent Guide to the Study of Pragmatism
Structural Polymorphisms in the Mannose-Binding Lectin Gene Are Associated with Juvenile Idiopathic Arthritis
Authors: GERGELY PÉTER , PAZÁR BORBÁLA , NAGY ZSOLT B. , GOMBOS TÍMEA , RAJCZY KATALIN , BALOGH ZSOLT , ORBÁN ILONA , SEVCIC KRISZTINA , POÓR GYULA
Published: April 2009

Objective.

To investigate the possible association between polymorphisms of the mannose-binding lectin gene (MBL2) and susceptibility to juvenile idiopathic arthritis (JIA).

Methods.

We performed a case-control association study including 118 Hungarian patients with JIA and 118 sex-matched healthy controls. MBL genotyping for the 3 mutant structural alleles at codons 54 (B), 57 (C), and 52 (D) in exon 1 and the promoter polymorphisms at position −550 (HL) and −221 (YX) were carried out by real-time PCR allelic discrimination. Serum level of MBL was determined by ELISA.

Results.

Variant allele frequencies of both codon 52 and 57 polymorphisms in the MBL2 gene were significantly overrepresented in JIA (p = 0.001 and p = 0.004, respectively). The frequency of low MBL genotypes (XA/XA, YA/YO, XA/YO, and YO/YO) in JIA was higher than that in healthy controls (p = 0.001). Serum MBL concentrations were found to be significantly lower in JIA patients versus control subjects (p = 0.001). The 2 promoter polymorphisms and codon 54 SNP of the MBL2 gene were not associated with JIA.

Conclusion.

Our findings suggest that genetically determined low MBL levels may predispose children to JIA in a Hungarian population. These data warrant further research to investigate the role of the lectin-dependent complement system in the pathogenesis of JIA.
Wireless Web Kids â?? Mobile Learning in Primary and Secondary Education
Authors: Jans Ruben , Awouters Valère
Published: April 2009

Wireless Web Kids (WW-kids) is an approved project with financial support of the Flemish government, Economics Department. The project started in December 2007 and runs till December 2010. Main purpose is to motivate children for studying sciences and technology. In Belgium there is a lack of students studying engineering, physics, chemistry, biology, technology and informatics. The project aims to enlarge the knowledge of children in primary and secondary education in the field of ICT in general, and new technologies as mobile devices for learning in particular. In the project students will learn and study with WEB 2.0 applications, using mobile devices. After the project children will have a clear inside how mobile devices can contribute to learning and working. The project is supported by companies and research units of the University of Hasselt.
Calibration of rolling ball viscometer in the intermediate reynolds number region
Authors: Hasan Muhammad Asad
Published: March 2009

The applicability of proposed correlations for the calibration of a rolling ball viscometer in the intermediate Reynolds number region (0.3 < Re 1000) has been studied. The constants for the equation correlating ball roll time with viscosity have been derived and compared with their experimental values. The dependency of these constants on temperature and on the dimensions of the viscometer has also been described which may help in the optimal design of a rolling ball viscometer.
Heat and mass transfer in non‐newtonian fluid flow with power function velocity profiles
Authors: Kawase Y. , Ulbrecht J. J.
Published: March 2009

Heat and mass transfer in laminar and turbulent non‐Newtonian fluids is investigated in this work using the power function velocity profiles. Analytical solutions are presented for cases of mass transfer in laminar non‐Newtonian fluid flows, namely for a flat velocity profile (plug flow), for the case of a constant velocity gradient at the solid boundary (Couette flow), and for the velocity distribution within a laminar boundary layer on a flat plate, and these are illustrated by rotating disks and cylinders in laminar Ostwald‐de Waele fluids. Further, turbulent mass transfer processes (tubular flow, rotating disk, and rotating cylinder) in non‐Newtonian fluids (Ostwald‐de Waele fluid and drag‐reducing fluid) at low and large Schmidt numbers are also discussed using the solutions of mass transfer in flows with power function velocity profiles. Reasonable agreement is found between the predictions of this work and the available experimental data and correlations.
Optimization of coal liquefaction reactors
Authors: Oǧuztöreli M. N. , Du Plessis M. P. , özüm B.
Published: March 2009

The method of Lagrangian multipliers of classical calculus is applied to obtain the optimum operating conditions of three continuous stirred tank reactors (CSTR) in series, to liquefy coal with minimum gas yield. In the formulation of the problem, the gas conversion was assumed to be the cost function. Results obtained were supported by the experimental findings in terms of liquefaction temperatures, reaction times, and conversion of coal into various liquefaction products.
Hydrodynamics of asymmetrical film thinning
Authors: Jeelani Shaik A. K. , Hartland Stanley
Published: March 2009

The thinning of the film beneath a liquid drop is often faster than predicted by radial drainage. This could be explained by asymmetrical drainage, but mathematical difficulties are then encountered. However, analytical solutions may be obtained for the two‐dimensional case and expressions are derived here for the asymmetric viscous drainage of films trapped between convex and concave wedges.

Solutions for the symmetrical drainage beneath wedges and parabolae are also presented which are analogous to the three‐dimensional drainage beneath cones and paraboloids previously derived.
Differential thermal analysis of reaction kinetics in pseudo‐isothermal state Part 2. Complex reaction
Authors: Matsuda Hitoki , Goto Shigeo
Published: March 2009

The complex reaction between urea and formaldehyde is studied by the simultaneous method of DTA in pseudoisothermal state and conventional titration, and the kinetic parameters and the heat of reaction are evaluated. This reaction is technically important in the production of urea‐formaldehyde resins. The conversions were determined from both the experimental DTA data and the concentration change of formaldehyde with time. By using the available values of the heat of reaction, the rate constants then could be obtained. The experimentally determined activation energies were in good agreement with those reported in the literature.
Heat transfer in co‐current vertical two‐phase flow
Authors: Oshinowo Toks , Betts R. C. , Charles M. E.
Published: March 2009

Heat transfer in co‐current two‐phase upflow and downflow of air–water has been investigated in a 25.8 mm electrically heated vertical pipe at 172.3 kPa for water mass velocities of 54 to 172 kg/m2s and gas flow rates of 0 to 1.322 × 10−2 m3/s. It was found that although the injection of air in the liquid flow increased the two‐phase heat transfer coefficients significantly for both systems, upflow coefficients were generally higher than those for downflow for the same liquid flow rate. This could have important implications in the design of some chemical reactors and heat engineering processes. Changes in heat transfer rates were found to occur at the flow pattern transition boundaries. Two‐phase heat transfer coefficients were well correlated by an expression based on dimensional analysis for both upflow and downflow.
Transfert de quantité de mouvement dans un ejecteur liquide—gaz vertical
Authors: Chung H. S. , Prevost M. , Bugarel R.
Published: March 2009

Momentum transfer between various liquids and gases has been studied in a vertical liquid‐jet ejector. A correlation based on dimensional analysis has been developed to predict entrained gas quantity as a function of various physical and transport properties of the system.
Mixed nickel‐aluminium oxides catalysts for the nitroxidation of toluene by no into benzonitrile
Authors: Abouarnadasse S. , Pajonk G. M. , Teichner S. J. , Germain J. E.
Published: March 2009

This paper describes the catalytic properties (activities, selectivities and stabilities with time on stream) of nickel oxide‐alumina aerogels and xerogels, towards the transformation of toluene by NO into benzonitrile at 440°C in a differential flow reactor.

The stability of the catalysts depends upon the NiO content. When the ratio Ni/Al increases to unity, the catalysts (aerogel as well as xerogel) are very stable with time on stream and are active and selective like pure nickel oxide. The latter is indeed initially active and selective, but very unstable with time on stream.

A redox model is proposed to explain the reaction mechanism.
Effect of oxidation on the viscosity of athabasca bitumen
Authors: Babu D. Ram , Cormack Donald E.
Published: March 2009

The effect of low temperature oxidation on the viscosity of Athabasca bitumen was investigated over the temperature range 320 to 370K, and to extents of oxidation as high as 41.7 × 10−3 kg‐O2/kg‐bitumen. Even at this relatively low extent of oxidation, the viscosity was observed to be more than two orders of magnitude higher than that of unoxidized bitumen. It was found that the Andrade viscosity model could adequately characterize the temperature dependence of the viscosity at all extents of oxidation. However, the pre‐exponential constant in the model was observed to be a strong function of extent of oxidation.
Solubility of SO2 in 1‐Methyl‐2‐pyrrolidinone and tri‐n‐butyl phosphate
Authors: Sanza Gregory J. , Klinzing George E. , Walker Richard J.
Published: March 2009

The ability of two organic solvents (1‐methyl‐2‐pyrrolidinone and tri‐n‐butyl phosphate) to remove SO2 from utility and industrial waste gases to an environmentally acceptable level was studied. Infinite dilution activity coefficients of SO2 for the systems were obtained by gas‐liquid chromatography. From these coefficients, the solubility data of SO2 were derived via a single‐parameter form of the Wilson equation in conjunction with regular solution theory. The results were quite comparable to data obtained from a classical bubble‐sparger apparatus.
Manganese oxide supported cobalt‐nickel catalysts for carbon monoxide hydrogenation
Authors: Varma R. L. , Dan‐Chu Liu , Mathews J. F. , Bakhshi N. N.
Published: March 2009

Performances of manganese oxide‐supported cobalt, nickel, and their combinations of varying compositions have been investigated for CO hydrogenation to lower hydrocarbons using a fixed bed microreactor at atmospheric pressure and temperatures ranging from 525 to 575 K. While Co/MnO was found to exhibit high selectivity to olefins in the C2–C4 range, the total yield of hydrocarbons was low. Addition of nickel to cobalt gave a stable catalyst having improved hydrocarbon yields while still retaining good olefin selectivity. The effect of operating conditions on product distribution was studied. Lower space times and higher temperatures favored olefin selectivity. A comparison of Ni and Co catalysts on various support materials was made. MnO‐supported Co catalyst gave significantly higher olefin/paraffin ratio than that obtained using conventional supports such as SiO2 or Al2O3. It was found that Co/MnO exhibited high water‐gas shift activity, and suppressed hydrogen uptake due to strong metal‐support interaction which favored olefin formation. This can be explained on the basis of competitive adsorption of water and hydrogen on the same surface sites resulting in low hydrogenation activity but improved olefin selectivity.
Breakup of relatively low‐concentrated O/W emulsion jets
Authors: Kitamura Yoshiro , Kizu Kyoko , Takahashi Teruo
Published: March 2009

The breakup of emulsion jets ejected downward into air from a nozzle has been investigated experimentally, and the breakup length of jets and the drop size for kerosene‐water emulsions have been measured. The concentration of the dispersed phase was less than 50 wt%, so all experimental emulsions exhibited Newtonian flow. Photographic observation indicated that the emulsion jet resembled the jet of normal homogeneous liquids. The breakup length of the jet and the drop size from the jet are in good agreement with predictions from stability analysis for normal liquids.
Prediction of surface tension of athabasca bitumen
Authors: Mehrotra Anil K. , Yee Chi‐Tak , Svrcek William Y.
Published: March 2009

Athabasca bitumen was characterized by dividing it into sixteen pseudo components. Using mean boiling point, molecular weight and specific gravity data, the critical properties of the pseudo components were estimated from available correlations.

Two approaches for the prediction of bitumen surface tension were investigated. It was found that the surface tensions predicted by the principle of corresponding states and the Rice‐Teja correlations were in general agreement with the published experimental data. In addition, these models successfully predicted the effect of temperature on surface tension at temperatures greater than about 60°C.
On jet flow in porous media as related to the spouted bed
Authors: Chen J. J. J. , Lam Y. W.
Published: March 2009

Potential flow equations for the combined rectilinear flow and a source are used to model the discharge of a jet into a porous media such as the condition in a fixed bed before spouting occurs. The equations derived are compared with data obtained using a measurement technique developed for determining the superficial velocity profile in a packed bed. This technique does not disturb the packing nor the actual flow field at the point where the data is required. The analytical results are also compared with the results of jet flow studies in the literature. In addition, by assuming ideal situations, an equation was derived for minimum spouting which closely resembles equations for predicting minimum spouting that are available in the literature.
Crystal growth rate dispersion
Authors: Tavare N. S.
Published: March 2009

Recent developments in the phenomenon of growth rate dispersion are surveyed with a particular emphasis on its characterisation. Most of the characterisation work concerning growth rate dispersion has been carried out under negligible nucleation conditions in batch configurations. Analytical solutions to the population balance equation for an MSMPR crystallizer under transient and steady state conditions are presented and their use in model discrimination and/or characterisation is discussed.
Hydrogen production by the catalytic steam reforming of methanol: Part 2: Kinetics of methanol decomposition using girdler G66B catalyst
Authors: Amphlett J. C. , Evans M. J. , Mann R. F. , Weir R. D.
Published: March 2009

The rate of catalytic decomposition of methanol in the presence of steam has been studied using a commercial Girdler G66B CuO‐ZnO low temperature shift catalyst from 150 to 250°C at atmospheric pressure. The mole ratio of steam to methanol was varied from 0 to 1.5, and the feed rates covered the range from 300 to 1400 kg s/mol. The data were successfully correlated using a simple reaction network involving CH3OH, H2O, CO and H2. A conventional reversible reaction rate equation was used which included a resistance term for site blockage by a CO surface complex. The methanol decomposition rate constants showed satisfactory Arrhenius behaviour with an activation energy of about 96 kJ/mole.
Catalytic activity of faujasite‐type zeolites towards the claus reaction
Authors: George Zacheria Mathew , Tower Robert Wayne
Published: March 2009

Commercial NaY and NaX zeolites showed significant catalytic activity towards the Claus reaction. Bronsted acidity retarded the catalytic activity to a much greater extent than Lewis acidity. Electron Spin Resonance (ESR) spectroscopic studies indicated the formation of SO2− anion radicals on the catalyst surface upon SO2 adsorption. The reactivity of SO2− towards H2S depended upon many factors. When the electron donating property of NaX was increased by impregnation with a small amount of NaOH, the Claus activity was enhanced and the activity of NaX containing 2.0 wt% NaOH was similar to that of a commercial Claus alumina catalyst. Infrared (IR) spectroscopic studies indicated physical and dissociative adsorption of H2S; SO2 was found to chemisorb on the zeolites.
Turbulent combustion of hydrogen in large volumes
Authors: Kumar R. K. , Tamm H.
Published: March 2009

The effect of fan‐induced turbulence on the combustion of hydrogen‐air mixtures has been studied in a 2.3‐m diameter sphere over a hydrogen concentration range of 4 to 42% (by volume). Two fans were used to produce the turbulence, which was measured at various locations by hot‐wire anemometry.

For low hydrogen concentrations (≤7%), turbulence increases the rate and extent of combustion; for large turbulence intensities the extent of combustion approaches 100%, and combustion times are reduced by factors of 8 to 10 from those observed under quiescent conditions. At high hydrogen concentrations, the effect of turbulence on combustion time is less pronounced than at low hydrogen concentrations. Inclusion of flame‐generated turbulence in the theoretical calculations sets an upper bound for the pressure rise, for the purpose of safety assessment.
Effect of the liquid entrainment on the predicted pressure drop in vertical flow‐boiling
Authors: Adeniji‐Fashola A. A. , Abdelmessih A. H. , Nejat Z.
Published: March 2009

Flow boiling in a vertical uniformly heated tube has been modelled employing the drift flux and two‐fluid formulations. The governing equations are solved numerically and the results presented in the form of pressure drop versus mass flux curves are compared to previously obtained experimental results.

The effect of the entrained liquid fraction at the transition from churn‐turbulent to annular flow when a switch from the drift flux model to the two‐fluid formulation is made is shown to affect the results and could improve the pressure drop predictions.
Size of bubbles and liquid circulation in a bubble column with a draught tube and sieve plate
Authors: Miyahara Toshiro , Hamaguchi Masahiko , Sukeda Yoshiaki , Takahashl Teruo
Published: March 2009

The size distribution of bubbles and the liquid circulation in a bubble column with a draught tube and sieve plate were studied experimentally. The size of bubbles is well correlated with the previous result of the authors; the size distribution data are fitted reasonably well by a logarithmic normal probability distribution. Gas holdup in the draught tube and annulus and pressure drop were measured and correlations for these parameters are obtained.

An energy balance is used to predict liquid circulating velocity using gas holdup and pressure drop correlations. Reasonable agreement is found between the calculated and measured circulating velocity.
Gas absorption with instantaneous chemical reaction in a laminar falling film
Authors: Basu Rahul , Ray P. , Dutta B. K.
Published: March 2009

Gas absorption in a laminar falling film with instantaneous chemical reaction with a reactant in solution has been theoretically analysed using a boundary immobilization technique. The profile of the reaction front, concentration distributions, the dimensionless quantity of gas absorbed and the enhancement factor have been computed for different values of the diffusivity ratio D and the concentration ratio β. Although the concentration distribution of the dissolved reactant is dependent on D and β, that for the dissolved gas is nearly independent of these parameters for small depth of penetration. The enhancement factor shows a convex profile for small D, an explanation for which has been provided.
Heat transfer from a horizontal smooth tube to a laminar falling film
Authors: MitroviC J.
Published: March 2009

For the case in which the liquid, freely falling between two adjacent horizontal tubes, forms a liquid sheet, Rogers (1981) gave an analysis of the heat transfer from the tube to the liquid. The flow within the film was assumed to be laminar. Some of the results obtained by Rogers are extended and discussed in the present paper. In particular, a simple relation is given for the angle θd, at which the thermal boundary layer intersects the film surface. This relation provides an easy means for calculation of the heat transfer coefficient and for determination of the range of parameters in which Rogers' analysis is applicable.
Mixing length equation for high schmidt number mass transfer at solid boundaries
Authors: Grifoll J. , Giralt Francesc
Published: March 2009

A simple modification of the Van Driest damping factor for mixing length calculations of mass and/or heat transfer coefficients at solid boundaries is proposed to increase mass eddy diffusivities in the near‐wall region, without affecting velocity predictions. Calculated mass transfer rates with a constant Sct = 0.85 are in good agreement with present and previous experimental results obtained in pipe and duct flows at high Schmidt numbers.
Absorption of carbon dioxide into laminar falling films of aqueous kaolin slurries containing sodium hydroxide
Authors: Hikita Haruo , Ishimi Kosaku , Egawa Akira
Published: March 2009

To confirm the theory for gas absorption accompanied by an instantaneous irreversible reaction in laminar falling films of power‐law liquids which was presented in a previous paper, experiments were carried out on the absorption of pure carbon dioxide into aqueous kaolin slurries containing sodium hydroxide by using a long wetted‐wall column. The experimental data were in fairly good agreement with the theoretical predictions, the average deviation being 3.0%. The discussion on the effect of the power‐law index of the liquid upon the reaction factor suggested an approximate method of estimating the reaction factors for power‐law liquids.
Effect of fluid density on flow in bagged electrowinning cells
Authors: Choo T. C. , Fujisawa T. , Toguri J. M.
Published: March 2009

In bagged electrowinning cells where there is gas evolution at the anode, such as the NiCl2 system, flow across a porous diaphragm bag is observed to occur predominantly from the bottom of the cell. A model based on a hydrostatic argument is proposed which can account for this phenomenon on the basis of bulk density difference between the catholyte and anolyte. Experimental evidence by means of visualization through acid‐base reactions shows good agreement with the model.
Phase behavior measurements of CO2‐SO2‐brine mixtures
Authors: Sayegh S. G. , Najman J.
Published: March 2009

Phase behavior and physical property measurements were carried out on mixtures of SO2‐H2O; CO2‐H2O, 5, 10, and 20 weight percent NaCl brines; and ternary CO2‐SO2‐H2O mixtures. The temperature was kept constant at 45°C, while saturation pressures were varied up to about 15 MPa. Binary measurements demonstrated that, at the same temperature and pressure, the mutual solubilities of SO2 and H2O are higher than those of CO2 and H2O. A three‐phase region has been identified in the termary CO2‐SO2‐H2O phase diagram at 7.24 MPa, but no such region was found at higher pressures.
Analysis of reaction zone thickness in non‐catalytic solid‐gas reactions
Authors: Rao T.Rajeswara
Published: March 2009

An expression for determining the reaction zone thickness in a slab type solid pellet is derived based on the grain model for first order and isothermal reaction. It is shown that during reaction, the zone thickness remains constant for slab type pellets and varies for cylindrical and spherical shaped pellets. An approximate criterion is obtained from the expression for the applicability of the widely used shrinking core and homogeneous models. The expression is also useful for determining the rate parameters. The expression is found to be very satisfactory in predicting the experimental reaction zone thickness values and the activation energy value for the zinc sulphide oxidation reaction.
Study of an air‐lift system, Part II: Heat transfer in co‐current, vertical two‐phase, non‐boiling flows
Authors: Grandjean B. P. A. , Ajersch F. , Carreau P. J. , Patterson I.
Published: March 2009

Heat transfer at the inner wall for co‐current vertical air‐water mixture flow has been investigated in a 161.5 mm diameter pumping tube of an air‐lift system. The experimental heat transfer coefficients were found to be significantly higher than those calculated from a single liquid phase correlation for the same liquid flow rate. The enhancement of heat transfer was found to be related to the flow pattern. A decrease of the heat transfer coefficient was observed in the transition region from slug flow to churn flow. Hydrodynamic and heat transfer models have been used to describe heat transfer during the slug flow regime and a correlation is proposed for the heat transfer coefficient in the liquid plug behind the gas bubble.
Kinetics of chemical desulphurization of coal in aqueous ferric chloride
Authors: Oshinowo Toks , Ofi O.
Published: March 2009

The kinetics of the chemical desulphurization of Lafia coal by the oxidation of the pyritic sulphur component with aqueous ferric chloride has been investigated. The oxidation rate was found to increase significantly with increasing temperature (60 to 102°C) and ferric chloride concentration (0.2 to 1.0M) but decreased with increasing coal particle size (‐0.210 mm to +0.841 mm). The kinetic data were well described by the unreacted shrinking core model with the indication that the desulphurization was predominantly chemical reaction controlled. The rate of reaction was also found to be well correlated by a two‐parameter pseudo‐homogeneous kinetic model. The specific rate constant obtained showed a true Arrhenius temperature dependence.
Liquid diffusion study by a holographic sandwich method
Authors: Paoletti D. , Spagnolo G. Schirripa , D'Altorio A.
Published: March 2009

The technique of sandwich holography is proposed for the study of diffusion in transparent liquid mixtures. The diffusion coefficient may be measured simply and directly from the interferogram obtained by shearing a sandwich hologram during reconstruction. Some preliminary results for the KCI‐water system are presented.
Conjugate heat transfer with laminar flow in an annulus
Authors: Sakakibara Mikio , Mori Shigeru , Tanimoto Akira
Published: March 2009

The solution to the conjugate heat transfer problem in an annulus with a heated (cooled) core and an insulated outside tube is presented. Three kinds of boundary conditions are considered for a chosen radius ratio.

From the results of parametric calculation over a wide range, it is concluded that wall heat conduction in a core can have substantial effects on the heat transfer characteristics in the areas surrounding the beginning and the end of the heat transfer section.
Simulation bidimensionnelle de phénomènes de convection naturelle et forcée en formulation primitive
Authors: Robichaud Michel , Methot J.‐Claude , Dupuis Marc , Dernedde Edgar
Published: March 2009

La simulation numérique en deux dimensions de la circulation de l'air, du profil de température et de pression pour des phénomènes de convection naturelle et forcée a été réalisée grâce à une méthode hybride aux différences finies basée sur la méthode MAC et utilisant la formulation Ψω. Trois problèmes différents ont été résolus: (i) convection forcée dans une enceinte fermée; (ii) convection naturelle dans une enceinte fermée; et (iii) convection naturelle et forcée dans une enceinte avec ouvertures et sources chaudes localisées. Les résultats sont comparés à la littérature pour les deux premiers problèmes et à des résultats expérimentaux obtenus avec une maquette pour le troisième problème.
The periodic steady state for cyclic energy storage in paraffin wax
Authors: Jariwala V. G. , Mujumdar A. S. , Weber M. E.
Published: March 2009

The thermal performance of a latent heat energy storage unit was studied experimentally at the periodic steady state generated by cyclic energy storage and recovery. The periodic steady state was obtained by alternating identical freezing periods with identical melting periods. The storage unit was a cylindrical container of commercial paraffin wax. Energy was transferred to (and from) the wax by temperature controlled water flowing through a submerged helical coil. Measurements were made of the amount of energy stored and recovered as functions of the freezing and melting times, the temperature of water and the geometry of the coil. A simple model was proposed to calculate the energy stored or recovered in the periodic steady state.
Cooling exothermic catalytic fixed bed reactors: Co‐current versus countercurrent operation in a methanol conversion reactor
Authors: Ravella A. , De Lasa H.
Published: March 2009

A comparison between two possible designs of exothermic catalytic fixed bed reactors, fully co‐current and fully countercurrent flow, was performed for the process of methanol transformation into hydrocarbons. The fully co‐current operation proved more appropriate, yielding, under low parametric sensitivity, higher productivities and allowing higher inlet methanol partial pressures.

The co‐current design showed, in a wide range of operating conditions, the Pseudoadiabatic Regime, a useful mode of operation. The countercurrent design did not allow Pseudoadiabatic Operation and had drawbacks such as multiple steady states and reactor ignition.
The importance of real‐fluid behavior and nonisentropic effects in modeling decompression characteristics of pipeline fluids for application in ductile fracture propagation analysis
Authors: Picard D. J. , Bishnoi P. R.
Published: March 2009

The importance of real‐fluid behavior during the rapid decompression of dense natural gas mixtures has been investigated using existing one‐dimensional models for real‐fluid isentropic decompression (RID) and perfect‐gas isentropic decompression (PID). The results show that the assumption of perfect‐gas behavior may result in significant errors. In the case of ductile fracture propagation (DFP) analyses, the fracture‐tip pressure level may be underestimated by more than 20 percent.

A real‐fluid nonisentropic decompression (RND) model has been developed in order to investigate the importance of nonisentropic effects in DFP problems. The results indicate that nonisentropic effects may be neglected for pipe sizes above approximately 508 mm O.D.
Measurement of heat of mixing for ammonium chloride + ammonia system at 25 °c
Authors: Yamamoto Hideki , Sanga Seiji , Tokunaga Junji
Published: March 2009

Heat of mixing for ammonium chloride in liquid ammonia at 25°C was determined in the concentration range 0‐50 wt% NH4Cl. It was calculated from the differential heat of solution observed in this work and the differential heat of dilution estimated from activities of solvent. A twin isoperibol calorimeter consisting of two stainless Dewar vessels was used at a relatively high pressure (up to 1.5 MPa). The accuracy of this calorimetry was examined by measuring the heat of solution for tris‐(hydroxymethyl)aminomethane(THAM) in 0.1 kmol/m3 HCl at 25°C, and satisfactory agreement within 1.1% between experimental and literature value was obtained. The reproducibility for the experiment was within 2.8%.
On the modelling of multicomponent acid extraction with long‐chain aliphatic amines
Authors: Stenström Stig , Wingefors Stig
Published: March 2009

The solvent extraction of phosphoric, hydrochloric, sulphuric, hydrofluosilicic and hydrofluoric acids with long‐chain aliphatic amins is modelled. Pure acid equilibria are based on existing isotherms or calculated extraction constants when only experimental data are available. For binary mixtures binary combinations of acid complexes are added. In the aqueous phase Bromley's model for electrolytes is used for calculation of ionic activity coefficients and the appropriate association/dissociation equilibria taken into account for calculation of ionic strength. For the organic phase an empirical model for the non‐ideal behaviour of phosphoric acid is used. For multicomponent mixtures at low acid concentrations the model calculates the extraction of phosphoric, hydrochloric and sulphuric acid almost quantitatively. For hydrofluosilicic and hydrofluoric acid the calculations are less precise and further information is needed about the different fluoride exchange equilibria involved.
Theoretical evaluation of the performance characteristics of a combined hemodialysis/hemoperfusion system — I. Single pass flow
Authors: Lee Chau‐Jen , Chang Yen‐Lin
Published: March 2009

A mass transfer model with single pass flow is proposed for evaluating the performance characteristics of a combined system composed of a dialyzer for hemodialysis (HD) and a coated adsorbent packed cartridge for hemoperfusion (HP). In the dialyzer, the mass transfer equation is represented in terms of three dimensionless parameters, i.e., extraction ratio, number of transfer unit, and ratio of flow rates. For the hemoperfusion cartridge, the model equations are derived by formulating the following four processes: convective mass transfer in the bed, fluid phase mass transfer around a coated adsorbent particle, transport across a film of coated membrane, and diffusion within an adsorbent particle. The Freundlich isotherm model is used for the adsorption on adsorbent particles. Applications of the mathematical model to systems to be potentially used in clinical practice are discussed. Solutions for two different sequences of arrangement, i.e., HD‐HP and HP‐HD, are obtained and discussed in terms of their performance efficacies. Theoretical results demonstrate that the HD‐HP arrangement will give better performance in most clinical encounters.
CO2 gasification of wood charcoals derived from vacuum and atmospheric pyrolysis
Authors: Plante P. , Roy C. , Chornet E.
Published: March 2009

The gasification of biomass derived char obtained via vacuum and atmospheric pyrolysis of Populus tremuloides has been studied in the ranges of 725–960°C and 0.1 to 6 MPa. CO2 was used as the oxidizing gas.

The results show that char reactivity is influenced by the preheating rates and that pressure effects are significant between 850°C and 950°C. A correlation based on the expression: df/dt = k0{exp(‐E/RT)}(1 ‐ f)afβPyCO2 was used to fit the experimental data.

In general, vacuum pyrolysis derived char showed a higher reactivity than atmospheric pyrolysis chars. An explanation based on a higher oxygen content of the vacuum pyrolysis char is suggested.
Kinetic study of isotopic exchange reaction between hydrogen and water vapor over a pt/sdbc hydrophobic catalyst sheet
Authors: Kawakami Koei , Isobe Minoru , Horiki Kanya , Kusunoki Koichiro
Published: March 2009

The isotopic exchange reaction between hydrogen and water vapor was studied for the temperature range 313 K to 353 K using 2.2% platinum supported on a hydrophobic styrene‐divinylbenzene copolymer (SDBC) sheet. With increasing relative humidity, the exchange rate increased, giving a stepped profile with a knee shape, and the reaction order with respect to hydrogen increased from almost zero to first order. In order to explain this unusual behavior, a simple kinetic model was proposed assuming that the water molecules are adsorbed in a multilayer on the platinum surface, and are subject to the exchange equivalent to finite number of layers. On the other hand, this multilayer of adsorbed water inhibits the transfer of HD to the platinum surface.
Decontamination of petroleum sludges by hot water extraction
Authors: Tran Francis T. , Couillard Denis , Rouleau Denis
Published: March 2009

The process of hot water extraction of tar sand was modified and adapted for removal of heavy oil from bottom tank petroleum sludges, and was submitted to a laboratory feasibility study. This process can also be utilized to clean beach sands contaminated by accidental heavy oil spills.

In the case of oil contaminated sands, a single stage extraction has yielded a 99% recovery of hydrocarbons and clean sands (containing less than 0.1% of hydrocarbons) which are thus safe to be returned to the environment.

In the case of petroleum bottom tank sludge, it was necessary to proceed with a double stage extraction with the addition of a wetting agent. A dosage of a Na2 Si O3 aqueous solution of 1% by weight has proven efficient, allowing an 82% recovery of hydrocarbons, with only 0.5% of hydrocarbons content in the solid residues.
Membrane formation through the phase‐inversion of Poly(vinylidene)/Dimethylformamide solutions. Experimental and theoretical study of evaporative flux
Authors: Francesconi R. , Castellari C.
Published: March 2009

The phase inversion of a polymeric solution is modeled assuming the validity of the diffusion equation and the existence of a mass‐cumulative stagnant film of vapor on the cast membrane. Unlike previous analyses, the model predicts a maximum in the evaporative flux leaving the polymeric solution. A comparison of theory with experiments indicates that the solvent flux is predicted only qualitatively. The discrepancy is probably due to some assumptions introduced, for mathematical tractability, in the model.
Prediction and experimental determination of vapour‐liquid equilibria for benzene + Cyclohexane + 1‐Butanol mixtures at 101.325 kPa
Authors: Arce A. , Bunco A. , Correa A. , Tojo J.
Published: March 2009

This article reports experimentally determined vapour‐liquid equilibrium data for benzene + cyclohexane + 1‐butanol mixtures at constant pressure of 101.325 kPa, and compares the results with those predicted by the group contribution methods ASOG‐KT and UNIFAC and by the Wilson, NRTL and UNIQUAC models after calculation of their adjustable parameters from the corresponding binary systems.
A general correlation for purely viscous non‐newtonian fluids flowing in ducts of arbitrary cross‐section
Authors: Tam K. C. , Tiu C.
Published: March 2009

An alternative correlation for the flow of purely viscous non‐Newtonian fluids in ducts of arbitrary cross‐section is proposed. It involves two dimensionless groups which are

Unique relationships exist between ϕ and Re*G for both laminar and turbulent flows which enable direct predictions of pressure drop from flow rate results or vice‐versa. Excellent agreement between the new correlations and available experimental data for purely viscous non‐Newtonian fluids flowing in circular tubes and square ducts is demonstrated.
Application of different criteria for uniqueness to the tubular reactor problem
Authors: Viuoen H. J. , Van Rensburg N. F. J.
Published: March 2009

A new sufficient condition for uniqueness is applied to the tubular reactor problem. The resulting criterion is compared to existing criteria. Better a‐priori estimates of the temperature solution were used to improve estimates on upper bounds for uniqueness. It is shown that these a‐priori estimates bear the primary responsibility for the better results.
Performance of a hydro‐filter — Mass transfer coefficient and gas‐liquid interfacial area
Authors: Uchida S. , Sumiyama M. , Kamo H.
Published: March 2009

An experimental study of the effect of operating conditions on the performance of a hydro‐filter (marble‐bed scrubber) has been conducted. The overall volumetric mass transfer coefficient, KGa, remains constant while the gas flow rate changes in the stable operating regions but increases sharply in the region above the loading point, corresponding to a sharp increase in the total pressure drop of the hydro‐filter. Since the gas flow is turbulent and the liquid flow is laminar under the present experimental conditions, the value of KGa is strongly dependent on the flow conditions of the liquid and its properties, while those of the gas have less effect.

The performance of a hydro‐filter as a mass transfer device is shown to be superior to other types of scrubbers although its main drawback is large pressure drop.
Calculation of some thermodynamic properties of gaseous water by means of BWR equation of state
Authors: Grozdanić D. K. , Djordjević B. D. , Tasić A. Ž
Published: March 2009

A procedure for estimation of constants in the Benedict‐Webb‐Rubin (BWR) equation of state from experimental P‐v‐T data of methane, ammonia and water is proposed. The new BWR constants for water have been estimated in the range 366 to 1144 K and 0 to 38 MPa. Compressibility factor, enthalpy and entropy for water have been evaluated with average absolute percentage deviations of 0.127, 0.409 and 0.286 respectively. The BWR equation is compared with other simple as well as complex equations in which the constants have been determined in the usual way. In all cases the BWR equation was the most successful.
Analysis of mass and energy balance equations in gas‐solid reactions
Authors: Oǧkuztöreli M. N. , Chambers A. , Özüm B.
Published: March 2009

Analysis of mass and energy balance equations for gas‐solid reactions are of particular importance in the interpretation of micro scale thermo‐gravimetric analysers, laboratory scale drop tube reactor data, and in the modeling of industrial scale reactors. In the present work we investigate the solutions of mass and energy balance equations for highly porous fine particle gas‐solid reactions in a relatively slow chemical reaction regime (chemical reaction control). Linearization of balance equations around the steady‐states does not provide a satisfactory approximation of the phenomena under consideration, implying that higher order terms are needed for a more accurate description of the process.
Catalytic reactions of n‐hexane on HY zeolite
Authors: Abbot J. , Wojclechowski B. W.
Published: March 2009

Catalytic reactions of n‐hexane on HY zeolite have been studied at 500°C. An examination of initial product selectivities shows that monomolecular processes are dominant. These include cracking to produce either C3 + C3 or C2 + C4 and skeletal isomerization. Bimolecular cracking processes account for only ∼ 5% of the total initial selectivity.

Methane was identified as an initial reaction product, but its formation is due to concurrent thermal processes. Molecular hydrogen was observed only as a secondary product.

The conversion of n‐hexane was fitted by a kinetic model previously applied to various n‐alkanes in the range C8 ‐ C16. In all these cases, the model shows that adsorption of reactants is strongly inhibited by product olefins. Addition of small amounts of olefin to the n‐hexane feed had no accelerating effect, which does not confirm results of previous studies.