bluuebunny/crossref_metadata_2025 huggingface dataset:
Variation in Volatile Leaf Oils of Seven Eucalyptus Species Harvested from Zerniza Arboreta (Tunisia)
Authors: Elaissi Ameur , Medini Hanène , Simmonds Monique , Lynen Frederic , Farhat Farhat , Chemli Rachid , Harzallah‐Skhiri Fethia , Khouja Mohamed Larbi
Published: February 2011

Leaves of seven species of the genus Eucalyptus L'Hér., viz., E. cladocalyx F. Muell., E. citriodora Hook., E. diversicolor F. Muell., E. fasciculosa F. Muell., E. grandis W. Hill, E. ovata Labill., and E. botryoides Sm., were harvested from Zerniza arboreta (region of Sejnene, northwest of Tunisia) in June 2007. Of the latter species, leaves were collected from trees having two origins, Morocco and Italy. Hydrodistillation of the dried leaves provided essential oils in yields varying from 0.4±0.0 to 3.3±0.1%, according to the species. E. citriodora had the highest mean percentage of essential oil amongst the species examined, whereas the lowest one was obtained for E. botryoides originating from Morocco. Analysis by GC (RI) and GC/MS allowed the identification of 140 compounds, representing 92.5 to 99.4% of the total oil composition. The contents of the different samples varied according to the species. The main components were 1,8‐cineole (2), followed by α‐pinene (1), p‐cymene, borneol, α‐terpineol, cryptone, spathulenol, trans‐pinocarveol (4), bicyclogermacrene (5), caryophyllene oxide, and β‐phellandrene. Principal components analysis and hierarchical cluster analysis separated the eight Eucalyptus leaf essential oils into five groups, each constituting a chemotype.
Insight into the Mechanism of Dihydrogen‐Heterolysis at Cyclopentadienone Iron Complexes and Subsequent CX Hydrogenation
Authors: von der Höh Adrian , Berkessel Albrecht
Published: February 2011

A bifunctional iron‐based catalyst (7), a compound related to the [Fe]‐ or Hmd‐hydrogenase, was studied by using experimental and computational methods. Catalyst 7 bears a protic hydrogen atom at the ligand and a hydridic hydrogen atom at the iron atom, which originate from the heterolytic uptake of H2, and can be transferred to unsaturated molecules (i.e. carbonyl compounds and imines). Our DFT calculations indicate that a non‐classical dihydrogen‐iron complex exists, and that the hydrogen uptake is an exergonic process. The hydrogenation of carbonyl compounds proceeds through a synchronous, concerted outer‐sphere mechanism, whereas the hydrogenation of the imine 18 is a two‐step process. In the first step, the imine is protonated to afford an iminium ion, to which the hydride is then transferred in a second reaction step. Energy hypersurfaces were calculated by using a solvent (toluene) continuum model.
Electron Microscopy of Cocatalyst Nanostructures on Semiconductor Photocatalysts
Authors: Hondow Nicole S. , Chou Yi‐Hsin , Sader Kasim , Douthwaite Richard E. , Brydson Rik
Published: February 2011

A thorough analytical electron microscopy investigation into the oxidized nickel cocatalyst structure on known photocatalytic materials NiTa2O6 and InTaO4 has been conducted. These photocatalyst materials have previously been reported in the literature to have activity in the splitting of water to form H2, and with the addition of a cocatalyst, such as NiO/Ni core shell nanoparticles, activity has been suggested to improve. Although important implications are placed on the effect of this cocatalyst, its structure has not previously been examined in detail. By using high resolution analytical transmission electron microscopy it has been determined that the structure is not as simple as suggested and, although a core shell metal/metal oxide structure is produced, in neither case is a perfect Ni/NiO composition obtained. In particular, in the case of the InTaO4 based material, the nominal NiO/Ni cocatalyst contains indium diffused into the nanoparticles from the photocatalyst support. The general implications of this result for the design of potential photocatalyst systems are discussed.
Predictive power of LDA to discriminate abnormal wine fermentations
Authors: Urtubia Alejandra , Roger Jean‐Michel
Published: February 2011

Wine fermentation is a critical step of winemaking. Unfavorable conditions can seriously affect the quality of the final product; however, it is difficult to anticipate these abnormal behaviors. In this study, the predictive power of stepwise linear discriminant analysis (SLDA) was evaluated to discriminate the behavior of wine fermentation. Information on different chemical concentrations from 18 industrial wine fermentations of Cabernet Sauvignon was used in this study. The statistical procedure consisted of curve fitting with exponential curve, and Stepwise LDA applied to the parameters of the curve. This methodology was applied to different times between the beginning and the end of fermentation (72, 95, 100, 150, 200 and 400 h). The results revealed that between seven and eight, of the 28 variables studied, minimized the Standard Error of Cross‐Validation (SECV) for the different times. In almost all times studied, correlation coefficient of alcoholic degree, initial concentration of glucose, initial density and correlation coefficient of tartaric acid were the variables more discriminant, and they indicated some differences between a normal and an abnormal fermentation, which need to be corroborated with more information. In this work, before 95 h, it was not possible to minimize the prediction error and find the most discriminant variables. Copyright © 2011 John Wiley & Sons, Ltd.
A new third‐order calibration method with application for analysis of four‐way data arrays
Authors: Fu Hai‐Yan , Wu Hai‐Long , Yu Yong‐Jie , Yu Li‐Li , Zhang Shu‐Rong , Nie Jin‐Fang , Li Shu‐Fang , Yu Ru‐Qin
Published: February 2011

A novel third‐order calibration algorithm, alternating weighted residue constraint quadrilinear decomposition (AWRCQLD) based on pseudo‐fully stretched matrix forms of quadrilinear model, was developed for the quantitative analysis of four‐way data arrays. The AWRCQLD algorithm is based on the new scheme that introduces four unique constraint parts to improve the quality of four‐way PARAFAC algorithm. The tested results demonstrated that the AWRCQLD algorithm has the advantage of faster convergence rate and being insensitive to the excess component number adopted in the model compared with four‐way PARAFAC. Moreover, simulated data and real experimental data were analyzed to explore the third‐order advantage over the second‐order counterpart. The results showed that third‐order calibration methods possess third‐order advantages which allow more inherent information to be obtained from four‐way data, so it can improve the resolving and quantitative capability in contrast with second‐order calibration especially in high collinear systems. Copyright © 2011 John Wiley & Sons, Ltd.
First Synthesis of Dodecasubstituted Porphycenes
Authors: Kuzuhara Daiki , Yamada Hiroko , Yano Keiko , Okujima Tetsuo , Mori Shigeki , Uno Hidemitsu
Published: February 2011

The synthesis of dodecasubstituted porphycenes has not been reported, to date. Herein, the preparation of tetramethyloctaethylporphycene by a McMurry‐type coupling of 3,3′,4,4′‐tetraethyl‐5,5′‐diformyl‐2,2′‐bipyrrole was attempted at first, but dodecasubstituted porphycene was not successfully obtained and only pyrrolocyclophene was obtained. The structure of the pyrrolocyclophene was determined by 1H NMR spectroscopy, FAB MS, and X‐ray crystal‐structure analysis. The pyrrolocyclophene was not successfully oxidized to porphycene. Then, the McMurry‐type coupling of bicyclo[2.2.2]octadiene (BCOD)‐fused 5,5′‐diacyl‐2,2′‐bipyrroles was performed and tetra‐meso‐octa‐β‐substituted (dodecasubstituted) porphycenes were successfully obtained for the first time. The structures were determined by 1H NMR spectroscopy and X‐ray crystal‐structure analysis. The crystal structures and NMR spectra were compared carefully with octasubstituted porphycenes, and there was a good correlation between the position of the substituents, the N1N2 and N1N4 distances of the porphycene inner nitrogen atoms, and NMR chemical shifts of the inner NH protons, which expressed the strength of NH⋅⋅⋅N hydrogen bonding between N1 and N2. These results suggested that the BCOD structure was relatively compact compared with common alkyl groups and that was why the dodecasubstituted porphycenes were available this time. UV/Vis absorption and fluorescence properties are also discussed.
Hydroxydialkylamino Cruciforms: Amphoteric Materials with Unique Photophysical Properties
Authors: McGrier Psaras L. , Solntsev Kyril M. , Zucchero Anthony J. , Miranda Oscar R. , Rotello Vincent M. , Tolbert Laren M. , Bunz Uwe H. F.
Published: February 2011

Two amphoteric cruciforms 6 and 7 (XF; 4,4′‐[(1E,1′E)‐(2,5‐bis{[4‐(dibutylamino)phenyl]ethynyl}‐1,4‐phenylene)bis(ethene‐2,1‐diyl)]diphenol, 4,4′‐[{2,5‐bis[(E)‐4‐(dibutylamino)styryl]‐1,4‐phenylene}bis(ethyne‐2,1‐diyl)]diphenol) were prepared by a Horner reaction followed by a Sonogashira coupling and subsequent deprotection. The XFs display significant changes in absorption and emission when exposed to trifluoroacetic acid, tetrabutylammonium hydroxide, and metal triflates. The substitution pattern of 6 and 7 leads to spatial separation of the frontier molecular orbitals, which allows the HOMO or LUMO of the XF to be addressed independently by acidic or basic agents. XF 6, which has hydroxyl groups on the styryl axis, displays changes in emission color upon exposure to ten amines in eight different solvents. The change in fluorescence upon the addition of amines was analyzed by linear discriminant analysis. These XFs may have potential in sensor applications for metal cations and amines.
Reduction of oxides of nitrogen in vent gases
Authors: Streight H. R. L.
Published: February 2011

Oxides of nitrogen are present in the effluent gases from nitric acid and nylon intermediates plants and if released in sufficient quantity they could be objectionable owing to their intensive reddish‐brown color and to their corrosive and poisonous nature. A paper study showed that the oxides of nitrogen could be reduced by absorption in an alkaline solution. Based on pilot plant tests, a large fume abatement unit was designed, installed, and operated in a satisfactory manner to reduce the concentration of the oxides of nitrogen. In 1956, the color of the combined effluent gases was practically eliminated when a more economic waste ammonia‐caustic liquor replaced the dilute caustic scrubbing solution and finely dispersed ammonium salts were removed in a Venturi scrubber. The method may be used to eliminate the objectionable brownish‐red color of effluent gases leaving a nitric acid plant.
The leaching of manganese from pyrolusite ore by pyrite
Authors: Thomas G. , Whalley B. J. P.
Published: February 2011

A new method of leaching low‐grade manganese ore (< 5% Mn) utilizing pyrite as a reagent was developed. By heating an aerated slurry of ore and pyrite and by recycling the leach liquor at controlled acidity to attack fresh ore, a manganous sulphate solution free of iron was obtained which when heated to about 175°C., yielded manganous sulphate monohydrate. During the leaching process, iron in the liquor was alternately oxidized by the pyrolusite and reduced by the pyrite. In an alternative leaching procedure, the heating of an aqueous slurry of pyrite in an autoclave first under oxygen pressure and then in the absence of oxygen produced an acidic ferrous sulphate solution suitable for the subsequent leaching of pyrolusite ore at ambient temperatures.
A study of black liquor oxidation in towers packed with asbestos cement plates
Authors: Murray F. E.
Published: February 2011

The process of black‐liquor oxidation is treated theoretically and an equation is derived for design purposes. Capacity coefficients were determined experimentally for two different arrangements of asbestos‐cement packing sheets. Data include those obtained from a study of a full‐scale commercial oxidation unit as well as those from an investigation using a pilot‐scale experimental tower with a modified arrangement of asbestos‐cement packing. Results from the pilot‐scale study indicate that the modified packing yields higher capacity coefficients than the packing in the full‐scale unit although the mass‐transfer coefficients are very similar for both packings using the pilot‐scale tower under rigorously controlled flow conditions, it was found that the capacity coefficients increase with increase in liquor flow rate and are virtually unaffected by changes in air‐flow rate when this is sufficiently high to provide adequate oxygen for the reaction. The significance of the experimental results is discussed in detail.
The mechanics of moving vertical fluidized systems: III. Application to cocurrent countergravity
Authors: Struve D. L. , Lapidus L. , Elgin J. C.
Published: February 2011

Previous studies in this laboratory have verified the assumption of a single fundamental relation between void fraction and slip velocity for counter‐current flow and batch fluidization of solid rigid particles in water. The present investigation was undertaken to test the applicability of a generalized theoretical analysis to the case of cocurrent counter‐gravity flow.

The cocurrent countergravity flow and batch fluidization of two ideal fluidized systems were studied experimentally in a 1 in. diameter column. The systems were 0.0184 in. diameter glass spheres‐water and 0.00396 in. diameter glass spheres‐water. Holdup, pressure drop, and fluid and particle velocities were measured for the cocurrent counter‐gravity flow experiments. Holdup and fluid velocity were measured for the batch fluidization runs.

Calculated slip velocities for cocurrent counter‐gravity flow and batch fluidization gave a single curve when plotted against holdup. It is therefore concluded that the experimental results support the validity of the basic assumption for the cocurrent countergravity flow of liquid‐solid systems.

The experimental data for cocurrent countergravity flow are in excellent agreement with the operating diagram (holdup as a function of fluid and particle velocities) for cocurrent countergravity flow determined from the holdup‐slip velocity relationship obtained from the batch fluidization experiments. Stable operation in the cocurrent counter gravity flow region where the fluid velocity is less than the single particle transport velocity is possible provided there is mechanical support for the solids and the solids flow rate is controlled at the bottom of the column. The application of the theory to the prediction of behaviour in compound cocurrent countergravity flow fluidized systems is demonstrated.
Some experiments on orifice sprays
Authors: Ranz William E.
Published: February 2011

New approaches to studies of spray systems were demonstrated by a series of experiments involving liquid jets spraying in liquids. Attention was focused on those conditions where the stresses causing breakup arose from the inertia of the surroundings and where the induced motion of the surroundings controlled the characteristics of the spray zone in front of the orifice. Experiments and analysis involved principle of balanced stresses, dispersion angle, motion of induced phase, development of spray zone, and drop size.
End effect corrections in heat and mass transfer studies
Authors: Johnson A. I. , Hamielec A. , Ward D. , Golding A.
Published: February 2011

Recently, considerable effort has been made to investigate mechanisms of heat and mass transfer to drops or bubbles passing through a continuous liquid medium. Many of these studies have been hampered by the unavailability of accurate methods for determining end effects.

This paper outlines methods of plotting efficiency measurements for the overall transfer process so that both the magnitude of the end effects and the mechanism of the steady fall or rise period may be investigated. The examples are drawn from mass transfer with resistance inside the dispersed phase and from heat transfer with resistance in both phases. For resistance in one phase the methods are straight line extrapolations.

Various mechanisms of transfer inside drops have been studied to test the methods of determining end effects.
The manufacture of chemical cellulose from wood
Authors: Wayman M.
Published: February 2011

This paper discusses progress made and problems associated with the manufacture of chemically pure cellulose from wood. The yield of pure cellulose which can be obtained from any wood species is limited by the chemical composition of the wood starting material. An examination of the chemical composition of various native wood species emphasizes the special potential of the genus Populus. Improved yield and good economy of manufacture of cellulose depends on the development of purification processes which are effective on less thoroughly digested wood. Conditions are developed for the most effective way of carrying out extraction of raw pulp with hot caustic soda. These include very high consistencies and very short times at high temperatures. The best conditions for extraction with strong caustic soda at low temperature are also reviewed. The need for properly designed equipment for both these processes is stressed. The special problem of removal of mannan is discussed. Two objectives are put forth: a more economical cellulose with today's standard of purity and chemically pure cellulose from wood.
Methods of noise control
Authors: Embleton T.F.W.
Published: February 2011

The best method of noise control is elimination of the noise at its source by modification of the noise producer; in certain cases this may not be possible since the normal functioning of the noisy device would be impaired. Alternatively the source may be enclosed, either completely or partially so as to shield the observer from the source. A third method involves the treatment of surfaces in the room containing the observer and noise source to absorb the noise as it is propagated through the room. Finally the observer, or at least his ears, may be enclosed by a soundproof booth or the wearing of ear defenders.

Examples of the successful quietening of pieces of machinery will be discussed, including the couch roll of a paper making machine. A reduction of 15–20 decibels in sound pressure level has been achieved without interference with the paper making qualities of the roll.
Tray drying of fine powders
Authors: Wheat J. A. , Macleod D. A.
Published: February 2011

Drying rates of finely powdered aluminum soaps and diatomaceous silicas were determined in a tray dryer. The weight of solid on the tray was automatically recorded. As expected for fine powders, plots of drying rate against moisture content were concave downward. The data were correlated by equations of the form N = aXG0.625 where N is the drying rate in lb./(hr.) (sq.ft.) and XG is the free moisture content in lb. of water per lb. of dry solid. A straight line was obtained by plotting log a for aluminum stearate against the reciprocal of absolute temperature and a similar relationship was assumed to hold for the other materials which were dried at two temperatures only. Intercepts of the temperature plots seemed to depend upon bulk density or average particle size but no general correlation was possible.
Empirical correlation of azeotrope data: An extension of the meissner‐greenfield correlation
Authors: Madonis J. A. , Johnson A. I.
Published: February 2011

The Meissner‐Greenfield correlations of azeotrope composition and boiling point have been checked with new data with satisfactory results except in the cases of hydrocarbons—acids and halogen hydrocarbons—acids.

A modification of these correlations for azeotrope composition has been extended to other combinations of organic liquids where the deviations from Raoult's law can be predicted from the hydrogen bonding characteristics of the components.

A simple empirical linear equation for azeotrope boiling point has been applied to most of the cases included in the above correlation.
A note on thermodynamic consistency of ternary vapor‐liquid equilibrium data
Authors: Li James C. M. , Lu Benjamin C.‐Y.
Published: February 2011

Graphical and numerical integration methods are proposed for testing the thermodynamic consistency of ternary vapor‐liquid equilibrium data, in which the integration of the Gibbs‐Duhem equation can be performed under isothermal and isobaric conditions. No data‐fitting procedure is involved in the proposed methods, therefore the uncertainty as to whether the deviations are due to experimental errors or to the inadequacy of the employed equation can be avoided. When one part of the data is less precise than the others, the proposed method may be employed to detect the inconsistent part.
Some thermodynamic properties of the system formic acid‐water
Authors: Plewes A. C. , Pei D. C. , Code R. K.
Published: February 2011

The integral latent heats of vaporization of formic acid‐water mixtures at 760 mm. Hg. are reported and used to prepare an enthalpy‐concentration chart for the system. The data provided a basis for the estimation of the heats of mixing in the vapor phase, and the results indicate that the exothermic heat of mixing may be attributed to the partial dimerization of monomeric formic acid coupled with the association of water and acid molecules.

Vapor‐liquid equilibria data for the system are also reported.
Rate control in the hydrometallurgical preparation of uranium dioxide
Authors: Wiles D. R.
Published: February 2011

Recent studies of the hydrogen‐precipitation of uranium dioxide from alkaline carbonate solutions have been extended. It was revealed that the reduction takes place in two phases. The first of these is the one described by Forward and Halpern. The second stage, much slower than the first, appears to be associated with the complete covering of the catalyst by the solid product. It is shown that while quantitative information is unreliable, a good qualitative description of the second‐stage reaction can be based on the diffusion of reactants through this product layer to the catalyst surface.
Aeration in tower‐type fermenters
Authors: Murphy D. , Clark D. S. , Lentz C. P.
Published: February 2011

The effects of air flow rate, oxygen partial pressure, aeration disk size and porosity, liquid height, and surface‐active agents on aeration were studied in two unstirred towers or column‐type vessels of different diameters using the sodium sulphite oxidation method. The coefficient of oxygen transfer increased with air flow rate up to the “flooding” point. The air flow rate required to cause “flooding” was increased by increasing the area of the aeration disk relative to the cross‐sectional area of the tower. Within limits, aeration was improved by using disks of finer porosity. Under most conditions the coefficient of oxygen transfer was much higher in the small tower. The coefficient of transfer was not affected by liquid height in the tower, but efficiency of absorption increased with height. Aeration was adversely affected by all surface active agents tested.
The effect of pressure on the enthalpy of gases
Authors: Kordbachen Reza , Tien Chi
Published: February 2011

A generalized enthalpy‐correction chart based on the law of corresponding states was constructed using the compressibility factor information reported by Nelson and Obert(6, 7). The range of pressures covered the region from Pr = 0.02 to Pr = 40, and the temperature extended from Tr = 0.265 to Tr = 12.5. The results produced from the correlation of this work have been found to agree with those obtained from some of the more sophisticated methods already presented in the literature.
Removal of a mist in a fluidized bed
Authors: Scott D. S. , Guthrie D. A.
Published: February 2011

The removal of droplets from a dioctyl phthalate mist by a fluidized bed of silica gel was studied. The mist used had a narrow range of droplet diameters, which averaged 0.87 microns in size. Silica gel particles were in the range of −150 mesh to +200 mesh.

It was found that removal efficiencies were only slightly affected by a 50% change in inlet mist concentration, or by a 300% variation in depth of the fluidized bed. Collection efficiencies varied from about 90% at low superficial gas velocities to 70% at high velocities.

It is shown from these results that collection is primarily by particle diffusion. Results can be correlated in terms of equations for mass transfer in fluidized beds. The possible uses of a fluidized bed as a collecting device are discussed.
Nuclear grade uranium tetrafluoride by the moving bed process
Authors: Hueston F. H.
Published: February 2011

After two years of research and development in the pilot plant stages, a plant for the production of nuclear grade uranium tetrafluoride by the Moving Bed Process has been designed, built, and successfully operated at Eldorado's Port Hope Refinery. This is the only production facility in the world using the moving bed technique for the production of UF4.

An exceptionally high grade uranium tetrafluoride, low in unconverted uranium oxides and uranyl fluoride can be obtained. A large percentage of the production exceeds 99% uranium tetrafluoride. Total metal contamination is less than 150 ppm.
Critical velocity of gas
Authors: Buthod A. P. , Tien Chi
Published: February 2011

Expression of critical velocity, based on thermodynamic consideration was obtained and is given by the following equation:

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or the ratio between the critical velocity and that of a corresponding ideal gas is given by

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Numerical values of X and Y were computed and presented on the generalized plot basis. Together with the value of heat capacity, this method enables the rapid calculation of critical velocity of real gas when the deviation from ideal gas behavior is significant.
Oxidation of ethylene using silver catalyst coated strips in an inert fluidized bed
Authors: Echigoya E. , Osberg G. L.
Published: February 2011

Fluidized bed tests with silver catalysts used in the oxidation of ethylene to ethylene oxide showed fluidization instabilities due to catalyst agglomeration. One method of avoiding the agglomeration problem, yet utilizing the excellent heat transfer property of a fluidized bed, is by the immersion of fixed catalyst coated strips in an inert fluidized bed. Small scale tests with this method, have shown that excellent temperature control can be achieved without serious adverse effects on catalyst performance. Kinetic data are presented for a limited range of flow conditions, and are correlated by an empirical rate equation of the form

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Evaporation rates in spray drying
Authors: Dlouhy J. , Gauvin W. H.
Published: February 2011

Heat and mass transfer coefficients have been determined during the evaporation of water sprays produced by pneumatic atomizing nozzles in a vertical, cocurrent spray dryer, 8‐in. in diameter and 14 ft. high, under various operating conditions. The progressive evaporation of the spray down the chamber was followed by taking samples of the drying air and of the water droplets at various distances from the nozzle, and a new volumetric method for the accurate determination of air humidities was developed.

For droplet spray ranging in mean diameter from 11.5 to 38.5 microns, the heat and mass transfer coefficients were found to be essentially the same as for single, stationary droplets evaporating in still air, the similarity being attributed to the almost equal diffusivity of the drop and of the air stream, resulting in negligible relative velocity. Certain important aspects of spray dryer design are discussed, and a method is outlined for the calculation of the residence time in the evaporation zone.
Pressure drop of single phase flow through raschig ring type tower packings: Effect of hole size
Authors: Fan Liang‐Tseng
Published: February 2011

The effects of hole size of the cylindrical tower packing on pressure drop of single phase flow were investigated. It was shown that the hole size had a profound effect on the correlation of pressure drop data. This was attributed to the difference in the characteristics of the spaces inside and outside the packing units and to the interlocking of the packing units in the beds.
Fundamental aspects of solids‐gas flow: Part IV: The effects of particle rotation, roughness and shape
Authors: Torobin L. B. , Gauvin W. H.
Published: February 2011

This paper examines the various complicating effects which rotation, surface roughness and shape impose on the motion and drag of single particles entrained in a fluid. In general, rotation appears to have little effect on the drag coefficient at low Reynolds Numbers, but influences the linearity of the motion and may thus play a part in the mechanism of particle entrainment in conveyed solids‐gas systems. Negative lift has been observed in the critical Reynolds Number region as the result of asymmetry in the wake structure. Surface roughness will cause an early transition to a turbulent boundary layer at higher Re values, which will result in an appreciable decrease in drag coefficient, but it may increase the drag at low Reynolds Numbers.

The effect of particle shape is more complex than has been suggested by previously published analyses. The available empirical correlations are discussed and compared, and indicate a dependency on the particle‐to‐fluid density ratio.
The corrosion behavior of aluminum in natural waters
Authors: Godard Hugh P.
Published: February 2011

This paper reviews the behavior of aluminum in contact with natural waters. The influence of water composition and service factors on corrosivity to aluminum are discussed. Laboratory pitting test methods are described and data are presented to support the existence of a cube root (in time) rate curve for the pitting of aluminum in water. Information on the pitting of aluminum in 17 Canadian waters is given and mention is also made of the pitting of aluminum in seawater and oil field brines. A statistical treatment of pitting data is presented. Finally, measures for extending the life of aluminum equipment subject to pitting by water are suggested.
Fundamental aspects of solids‐gas flow: Part V: The effects of fluid turbulence on the particle drag coefficient
Authors: Torobin L. B. , Gauvin W. H.
Published: February 2011

This article presents an analysis of the experimental evidence presently available on the effects of the free‐stream turbulence on particulate momentum transfer, obtained from both wind‐tunnel tests with stationary bodies and from single‐particle systems in which the solid is moving freely with the stream. Original experimental measurements recently obtained with a radio‐tracer technique are also included. The drag coefficient appears to depend primarily on the magnitude of the relative turbulence intensity and on the particle Reynolds Number, while acceleration has negligible effects. Increasing intensities cause a systematic regression of the transition region of the drag coefficient curve towards lower Reynolds Numbers, together with a moderate increase of the drag coefficients for both the subcritical and supercritical Reynolds Numbers. The momentum transfer behavior suggests the occurrence of a laminar‐turbulent transition in the attached boundary layer at a critical value of the Reynolds Number for a given relative intensity. Indirect evidence involving heat and mass transfer phenomena appears to support this hypothesis.
Design of steam tracing systems for protection against freezing
Authors: Cotton W. S.
Published: February 2011

Process or service pipe lines containing materials which freeze readily must be protected during shutdown periods in cold weather. The desired temperature may be maintained in the pipe by installing a steam‐heated tube under the pipe, and enclosing both the pipe and tracer tube with the insulation. A rational thermal design method has been developed which permits the estimation of the heating requirements. The method may also be applied to tracers containing other heating media.
Optimal bypass rates for sequences of stirred tank reactors
Authors: Aris Rutherford
Published: February 2011

A general method of finding the optimal volumes, temperatures and bypass rates for a sequence of stirred tank reactors is developed. After a discussion of the method of dynamic programming, the example of a sequence of adiabatic reactors of equal volume with a single reaction is used as an illustration. A simple graphical construction for determining the optimal bypass rates is given for this case. The limiting cases of the optimal control of a batch reaction by addition of cold feed is also solved.
The effect of intraparticle temperature distribution on the catalytic effectiveness factor of a porous catalyst
Authors: Akehata T. , Namkoong S. , Kubota H. , Shindo M.
Published: February 2011

The effect of intraparticle temperature distribution on the catalytic effectiveness factor is derived, and its magnitude is estimated using an approximate solution. These calculations show that for the several cases examined the term containing the effect of temperature is less than 10% of that due to the concentration effect.
Taylor diffusion in tubular reactors
Authors: Coste Joseph , Rudd Dale , Amundson Neal R.
Published: February 2011

In order to estimate the effect of velocity profile and radial diffusion on conversion in tubular reactors the assumption of Taylor diffusion is adopted. This leads to equations which are simple, but because of the numerical instability of these equations they are approximated to by a cell model in order to obtain numerical results. It is shown that the cell model can be a very good approximation to the one dimensional diffusion equation. If the Taylor diffusion model is valid for systems involving chemical reaction and heat transfer it may be concluded that while there seem to be no gross effects in a tubular turbulent reactor there are differences in detail, such as maximum temperature at the hot spot, which may be important.
Pilot plant unit for the continuous methanolysis of glyceride oils
Authors: Jangaard P. M. , Vandenheuvel F. A.
Published: February 2011

Efficient continuous methanolysis using an alkaline catalyst is achieved in the simple system described.

At 100°C., in one hour, a volume of oil equal to six times the free volume of the reactor is converted to methyl esters.
Optimum performance of combined flow reactors under adiabatic conditions
Authors: Cholette A. , Blanchet J.
Published: February 2011

Irreversible first‐ and second‐order reactions are studied for combinations of tubular and CST reactors when endothermal or exothermal adiabatic conditions prevail.

Typical results presented for MT and TM models show the variation of either the conversion or the relative residence time as a function of the mixing level of the system.

A graphical method, applicable generally to MT reactors, provides a simplification over that of successive approximations required for model TM.

For the conditions investigated broad limits are indicated of the optimum reactor combinations.
The hydraulic characteristics of two‐phase co‐current flow through glass fibres
Authors: Gunn D. J. , Aitken A. R.
Published: February 2011

The mechanism of flow of air and water through packed glass fibres has been studied. Pressure drops and liquid hold ups were measured as a function of gas and liquid flow rates and the packing characteristics. It has been found that the pressure difference measured is dependent upon the history of previous gas and liquid flow rates in the bed. The liquid hold up is defined entirely by the gas and liquid flow rates. An analysis of the flow mechanism shows that the capillary forces interact with the fluid pressures in the bed. For example an increase in gas flow rate followed by a reduction to the same flow rate has been shown to reduce the resistance of the bed to gas flow even though the liquid flow rate is unchanged. A measure of the irreversibility of the flow operation is suggested.
The relation between the Margules and van Laar equations: The square‐root equation
Authors: Otterstedt J.‐E. A. , Missen R. W.
Published: February 2011

The excess free energy of mixing (ΔGE) has been used to show that the Margules and van Laar equations are reciprocally related. Thus if the Margules equation is written as χG = ΔGE/x1x2 = Σakx1k, then the van Laar equation can be written as χG−1 = Σbkx1k. It is known from previous work that the Margules equation does not adequately represent the thermodynamic properties of solutions of alcohols in non‐polar solvents over the whole range of composition, and it is pointed out that the van Laar equation cannot be used if the excess function changes sign. In such cases the use of a square‐root analogue of the Margules equation, χG = Σckx1(k‐2)/2, is proposed. This equation satisfactorily accounts for the rapid increase in χ as the mole fraction of alcohol becomes small and is empirically useful. However, it has theoretical disadvantages; it cannot be used to determine by extrapolation the value of the partial molar excess thermodynamic property for component 1 in an infinitely dilute solution; furthermore, it predicts a violation of the second law in the case of free energy of mixing for solutions dilute in component 1, but the region of violation lies outside the experimental range for x1 as low as 0.01.
A review of mass transfer to interfaces
Authors: Harriott Peter
Published: February 2011

The theories for mass transfer to rigid or mobile interfaces are reviewed and compared with selected experimental data. Except for transfer to particles in stagnant fluids, there is no case where the rate depends on the first power of the diffusivity, as implied by the film theory. The transfer coefficients for single rigid spheres, for particles in packed beds, and for the gas film in packed absorbers vary with about the 2/3 power of the diffusivity, as predicted by the boundary layer theory, which works fairly well for these cases because transfer to the wake region is relatively small. The penetration theory holds exactly for many devices which expose liquid surfaces for a short and known contact time, and, judged by a 0.5 exponent for the diffusivity, the penetration theory probably holds for the liquid phase in absorbers and for both phases in bubble‐cap towers. Theory and data for transfer to mobile interfaces show the coefficients to vary with D0.5 to D3/5, the limiting solutions for high and low interface velocity corresponding to the penetration theory and the boundary layer theory. Mass transfer in turbulent fluids is an unsteady‐state process, and the transfer coefficient varies with the 0.5‐0.8 power of the diffusivity even with very high turbulence.
The reduction of pressure gradients in oil pipelines by the addition of water: Numerical analysis of stratified flow
Authors: Charles M. E. , Redberger P. J.
Published: February 2011

The addition of water to crude oil pipelines appears to be an important method for decreasing the pressure gradient for a given oil throughput. Although the concentric oil‐in‐water flow pattern provides the greatest possible reduction, the general case, in which the liquids are stratified as a result of the oil and water having different densities, is also characterized by reductions in pressure gradient.

To evaluate the magnitude of the pressure gradient reduction to be expected in stratified flow systems, the Navier‐Stokes equations were solved by a numerical procedure utilizing a digital computer, for the laminar stratified flow of two Newtonian liquids — oil and water — in a circular pipe. Liquid flow rates were obtained for the flow of five hypothetical oils ranging in viscosity from 4 to 1500 centipoises in the presence of water, by computing the oil and water velocity profiles for a series of arbitrary oil‐water interface positions. It was found that the maximum values for the pressure gradient reduction factor ranged from 1.12 to 1.31 for the five oils and occurred at water contents ranging from 12 to 93 per cent respectively.

The computed reduction factors were considerably lower than experimental values and this appears to indicate that wave motion and mixing at the oil‐water interface produces a further and very significant reduction in the pressure gradient.
Simultaneous heat and mass transfer in a fluidized bed of drying silica gel
Authors: Heertjes P. M.
Published: February 2011

The determination of the partial coefficients of heat and mass transfer in air from and to a drying fluidized mass of silica gel is given. The analogy between the two methods of transport in the bed has been studied by an inspection of the relation between the two coefficients. A correlation of these coefficients with the void fraction, the superficial velocity, the particle size and the tube diameter of the bed has been derived. This correlation has been transformed into a correlation of dimensionless groups.
Effects of water vapor content on the inflammable limits of ammonia‐oxygen‐nitrogen mixtures
Authors: Decoursey W. J. , Zubryckyj N. , Yoshida N.
Published: February 2011

A study was undertaken to confirm and extend available information on the inflammable limits of ammonia in air or oxygen‐nitrogen mixtures, and particularly the effects of water vapor on these limits. Such information should prove helpful in the prevention of explosion in equipment handling these gas mixtures, for example in the autoclaves for leaching of nickel sulphide concentrate under pressure, with ammonia and compressed air. Flame‐quenching technique was used for determinations at atmospheric pressure, and the dynamic bomb method at ten atmospheres.

At atmospheric pressure, the inflammable limits of ammonia in dry air were found to be 17.2 and 30.2% ammonia, but these limits were found to narrow as the water vapor is increased, until at 10.8% H2O and 20.8% NH3 no flame could survive. With a dry oxygen‐ammonia mixture, the lower limit was found to be 15.2% ammonia. At ten atmospheres, the explosive limits of ammonia in dry air were found to be 16.9 and 28%, and these limits were narrowed with addition of water vapor until, above 9% water, no explosion occurred.
A correlation of mass transfer data of solid‐liquid systems in agitated vessels
Authors: Marangozis J. , Johnson A. I.
Published: February 2011

Studies of mass transfer between solids and liquids for agitated vessels have been reviewed. Data from the literature correlated empirically by the Gilliland‐Sherwood correlation, regardless of the actual geometry of the apparatus, in two main categories.

The velocity term in the Re number was defined as the velocity of the rotating device, i.e., impeller, cylinder or rotating annulus. The characteristiclength term was taken as the impeller diameter in the cases of mass transfer from suspended pellets or flat surfaces, the gap‐width in the case of rotating cylinders, and the hydraulic radius of the annulus in the case of rotating vessels.

The empirical correlations were found to be in general agreement with the turbulent boundary layer mechanism of mass transfer.
Kinetic studies of the thermal decomposition of ferric sulphate and aluminum sulphate
Authors: Warner N. A. , Ingraham T. R.
Published: February 2011

Kinetic studies were made of the thermal decompositions of ferric sulphate and aluminum sulphate. The reaction product gases were swept from the samples. Cylindrical pellets prepared from chemically pure anhydrous powders were used, and mathematical corrections were made to relate the reaction rate to the area of the interface between the undecomposed sulphate and the oxide product. The interface is the local of the reaction. The rate of the decomposition reaction is proportional to the area of this interface. Studies on ferric sulphate have shown that the rate of decomposition is also directly proportional to the difference between the equilibrium pressure of sulphur dioxide (or oxygen) over the sample and the partial pressure of sulphur dioxide (or oxygen) in the gas stream. The activation energies are 19.9 kcal. and 64.0 kcal. respectively for the ferric sulphate and aluminum sulphate decompositions. No oxysulphates were detected as intermediates in the transition from the normal sulphates to the oxides.
The agglomeration of aqueous suspensions of graphite
Authors: Sutherland J. P.
Published: February 2011

A description is given of a practical technique for producing compact spherical agglomerates from a liquid suspension of solids following a method outlined by Farnand, Smith, and Puddington. This method involves the addition of an immiscible liquid which preferentially wets the solids and forms liquid bonds between colliding particles. Using a rotatingdrum agglomerator, pellets ranging in size from 0.020 to 0.75 in. diameter were produced from an aqueous suspension of finely‐divided graphite. The effects of operating variables such as drum load, speed of rotation, suspension and bridging liquid concentrations are described, followed by a discussion of the mechanism of particle growth. Selective agglomeration is also described.
Transient activity and replacement of catalyst in multistage reactors
Authors: Wen C. Y.
Published: February 2011

Equations are derived for the transient activity of flow medium in multistage continuous flow reactors. Activity behavior of linear, exponential, and step change is considered. Complete mixing in each stage is assumed. Application to a fluidized bed reactor is presented and a method of obtaining mixing coefficients is given.
Ion‐exchange diaphragms for caustic‐chlorine cells
Authors: Chrysikopoulos S. , Tombalakian A. S. , Graydon W. F.
Published: February 2011

The possibility of employing ion‐exchange diaphragms for caustic‐chlorine cells was investigated. Caustic soda of low salt content was produced by batch and by continuous electrolysis of sodium chloride in a two chambered cell separated by a polystyrene sulphonic acid cation‐exchange diaphragm. Caustic soda solutions as high as 41% by weight and containing less than 1/10 of 1% sodium chloride were obtained directly from the electrolysis cell.

Measurements also were made to determine the effect of cell operating variables on the energy consumption for this electrolytic process. A marked dependence of energy efficiency on ion‐exchange diaphragm properties, current density, and concentration of caustic soda solution produced was observed. The experimental data were graphically correlated to allow practical interpretation.
Interfacial tension gradients and droplet behavior
Authors: Schechter R. S. , Farley R. W.
Published: February 2011

The rate of droplet settling and mass transfer are known to be quite sensitive to small quantities of surface active impurity present in the interface. The purpose of this paper is to examine critically several of the models used for predicting the rate of inhibited Stokesian settling and to compute the rate of mass transfer from the surface of a slowly settling droplet in the presence of surface active impurities which are distributed over the surface.
Air pollution control with fibre mist eliminators
Authors: Brink J. A.
Published: February 2011

Difficult air pollution problems caused by the emission of submicron mists have been solved with fibre mist eliminators. This new equipment is the result of extensive research and development at Monsanto.

This paper describes some air pollution problems which have been solved successfully with fibre mist eliminators and suggests some new problems which should be solved in the future.
Simultaneous development of velocity and temperature profiles for laminar flow of a non‐Newtonian fluid in the entrance region of flat ducts
Authors: Yau Joseph , Tien Chi
Published: February 2011

The momentum and energy integral method of von Karman and Pohlhausen is used to solve the entrance heat transfer problem for a non‐Newtonian fluid in a flat duct. The initial temperature and velocity profiles are assumed to be flat. The fluid is assumed to obey the Ostwald‐de Wael model and its physical properties are assumed to be constant. Dimensionless expressions for temperature and velocity profiles are obtained by numerical methods.

The results of this investigation indicate that, similar to the case of Newtonian fluid, the parameters which influence entrance heat transfer are x/b ratio, Reynolds number and Prandtl number, provided these groups are properly defined.