bluuebunny/crossref_metadata_2025 huggingface dataset:
A shock tube study of the high temperature reactions of nitrogen with hydrocarbons
Authors: Rao V. V. , Mackay D. , Trass O.
Published: March 2009

A single pulse shock tube has been used to study the reactions of nitrogen with methane, ethane and acetylene at 1400°‐6000°K. Reactants heated by the reflected shock for about 1–1.5 milliseconds are cooled by rarefaction waves, and samples obtained through a quick‐opening check valve are analyzed by gas chromatography. The effect of nitrogen on hydrocarbon pyrolysis appears to be negligible below about 2000°K. At higher temperatures, vibrationally excited nitrogen molecules react with free radicals and produce hydrogen cyanide. Activation energies in the range 23 to 54 Kcal/mole are calculated for the formation of hydrogen cyanide.
Zeta potential measurements of fibres. D‐C. Streaming current method
Authors: Chang M. Y. , Robertson A. A.
Published: March 2009

Streaming current techniques have been extensively used in measurements of zeta‐potential, ζ, at the solid/liquid interface of capillary systems. In the case of porous, swelling and deformable materials, the application becomes less certain because of the complex geometry of the flow paths and interactions of neighboring electric double layers. The applicability of the equations developed by Goring, Biefer and Mason to papermaking fibres in various electrolytes is examined and found inadequate. An exponential form of the concentration function in the streaming current equation is proposed, IηL/pD = (Aζ/4π) exp(–Bc), and its reliability in evaluating ζ, is demonstrated. Factors affecting the parameter B are discussed.
The enthalpy of simple, dense fluid mixtures
Authors: Orentlicher M. , Pravsnitz J. M.
Published: March 2009

Upon using relations suggested by the statistical theory of dense fluids, a method is developed for calculating the enthalpies of simple fluid mixtures at conditions in the neighborhood of the critical. The method is suitable for calculations using an electronic computer and appears to give good results for mixtures of simple nonpolar gases and liquids at low temperatures.
On the mechanism of bubble formation in a fluidized bed
Authors: Ruckenstein E. , Muntean O.
Published: March 2009

A mechanism of bubble formation in a nonhomogeneous fluidized bed, based on instability theory, is suggested. In this mechanism it is assumed that the “bubbles” are formed at the bottom of the bed by the growth of prominences appearing because of the instability to perturbations of the lower surface of the bed. A bubble breaks off when the volume of the prominence becomes sufficiently large so that the buoyant force equals the sum of the bed resistance opposing its growth and the inertial forces. An equation for the diameter of the departing bubble is established.
Settling length for turbulent flow of air in an annulus
Authors: Nicol A. A. , Medwell J. O. , Goel R. K.
Published: March 2009

The settling length, or distance downstream from the entrance required for the development of the velocity profile, has been determined for four square entrance sectioned annuli, with diameter ratios of 0.2, 0.3, 0.5 and 0.7. Using air, a Reynolds number range of 5,000 to 50,000 was covered, and correlations have been obtained relating the settling length, equivalent diameter, Reynolds number and diameter ratio.

The expression L/De = 0.795 Re374(D1/D2)−0.60 correlated the data for Reynolds numbers lower than 22,000 and for Reynolds numbers greater than this the relation was L/De = 15.96 Re.077(D1/D2)−624.
Non‐newtonian flow through open channels
Authors: Kozicki William , Tiu Carlos
Published: March 2009

A general method is proposed for prediction of the flow rate and maximum velocity in the isothermal, steady, uniform, laminar flow of any incompressible, time‐independent non‐Newtonian fluid in straight open channels of arbitrary cross section. The method requires only a knowledge of two geometric coefficients and a function of shear stress, used to characterize the behavior of the fluid model. The slip effect at the solid boundary has been taken into consideration. Numerical values of the geometric parameters have been determined for flow through an inclined plane of infinite width, semi‐circular, semi‐elliptical, rectangular, and 90° and 60° symmetric triangular open channels. Applications have been made to various non‐Newtonian fluid models such as the power‐law, Bingham, Ellis, Meter and the Reiner‐Rivlin general model. Numerical examples are presented.

A generalization of the Fanning friction factor — Reynolds number is also presented. The problem of determining the point of transition from laminar to turbulent flow in the general case is examined, as is the problem of prediction of the friction factor in turbulent flow.
The free‐settling of solid cylindrical particles in the turbulent regime
Authors: Isaacs Jack L. , Thodos George
Published: March 2009

Experimental measurements have been conducted to establish a correlation for the settling velocities of cylindrical particles whose length to diameter ratios varied from 10 to 1/10 and Reynolds numbers between 200 and 60,000. It was found that separate correlations exist for cylinders of L/D > 1.0 and for L/D < 1.0. These relationships are expressed analytically and were found to be independent of the Reynolds number. In addition, a qualitative description of the motion generated by the particle during settling has been discussed for cylinder of L/D less than, equal to, and greater than one.
Direct contact condensation of steam in a packed column with immiscible heat transfer agents
Authors: Rai V. C. , Pinder K. L.
Published: March 2009

Steam was condensed in a four inch inside diameter column packed with three‐eighth inch ceramic Raschig rings using Aroclor 1242 and 1248 as co‐current heat transfer agents. The packing heights used for condensing the steam were estimated from the liquid temperature profile in the column. From this value and the liquid temperatures the height of a transfer unit for condensation (HCU) was calculated. The HCU was found to be strongly affected by the mean heat transfer medium viscosity and by the flow rate of the liquid. Two empirical equations have been developed to describe the results of this study. Both are of the form
The Heated Surface Probe for Measuring Shear Stress at the Wall in Laminar Boundary Layers
Authors: Rotem Zeev
Published: March 2009

A heated‐surface instrument for the measurement of wall shear‐stress was apparently first used by Ludwieg (2). Its main advantages over the more common Stanton tube is the comparatively very minor disturbance of the flow, even within the wall boundary layer, caused by the instrument, and its high sensitivity. The present paper describes modifications to Ludwieg's original probe, its use with a masstransfer process, and gives a more reliable analysis of its performance.
Heat and mass transfer to spheres in high‐temperature surroundings
Authors: Narasimhan C. , Gauvin W. H.
Published: March 2009

An experimental investigation of the combined natural and forced convective effects was carried out which involved the measurement of the rate of evaporation of water from porous stationary spheres (1/4, 3/8 and 1/2‐in. in diameter) under steady conditions in an electrically‐heated stainless steel chamber. The spheres were suspended in a stream of super‐heated steam at atmospheres ranging from 50 to 1000°K. Both the opposing and aiding flow cases were investigated. The Reynolds number varied from 0 to 1489 and the turbulence intensity was less than 1%. The parameter [(Gr)/(Re2)] was found to be of fundamental importance in correlating the results. The rates of heat transfer in the mixed flow region for the opposing flow case was higher than for aiding flow. The transition between the two mechanisms was found to be gradual but very complex in the case of opposing flow.
Analysis of some random blending processes
Authors: Krambeck F. J. , Shinnar R. , Katz S.
Published: March 2009

A common problem in the design of mixing and blending equipment is the estimation of the size of the equipment needed to achieve a certain specification. If the statistical properties of the non‐uniformities in the production lots to be blended are known one can calculate by known methods (1) the reduction in the variance of the product properties. Specifications however are normally given not in terms of a variance but in terms of limits. These can be estimated from the variance by assuming a Gaussian distribution. In this paper a method is discussed which allows one to calculate these limits directly for some blending problems in which the source of the nonuniformity is due to the production of an off‐grade lot. This not only allows more accurate design procedures, but also gives some insights as to the magnitude of the error made by assuming a Gaussian distribution.
Direct contact heat transfer between two immiscible liquids during vaporization: Part II: Total evaporation time
Authors: Prakash C. B. , Pinder K. L.
Published: March 2009

A dilatometric technique was used to determine the total evaporation time of individual drops of furan, isopentane and cyclopentane as they rose in water.

The values of total evaporation time were predicted reasonably well for each system by a different equation than was used to correlate the evaporative data for the initial 10% of the evaporative process as reported in Part I of this study. The total evaporation time data were also compared with the correlations given by Klipstein (1), by Sideman and Taitel (2) and with the correlation which was found by the authors to best fit the total evaporative data for the three systems.

In agreement with Klipstein (1), the correlation for the overall heat transfer coefficient was found to be one of the form, qA = Cd12.0δt.

The rate of rise of an evaporating drop for the conditions used in this study was found to be nearly equal to the instantaneous terminal velocity.
On the derivation and application of a new vapor pressure equation
Authors: Narsimhan G.
Published: March 2009

Starting from the Clapeyron equation and making use of the equivalent expression for the reference state for latent heat of vaporization of pure liquids, namely at 0°K., a new vapor pressure equation is derived as follows:

χ(Tr) has been tabulated for Tr values in the range 0.50 < Tr <0.99 after programming on an IBM 1620 computer. The new vapor pressure equation has been tested with a variety of liquids both polar and non‐polar, and found to predict vapor pressure data in the orthobaric range with an average error of ± 1.90% and maximum error of ± 3.20%.

A significant outcome of this investigation is the identification of Riedel's factor αo and Pitzer's acentric factor ω These have been shown to be functions of critical properties and reduced boiling point.
Rates of dissolution of potash ore
Authors: Husband W. H. W. , Ozsahin Selim
Published: March 2009

A long‐term program was undertaken in 1960 at the Saskatchewan Research Council to study the feasibility of solution mining potash ore. Appropriate scientific and engineering data for such a study were not available in the technical literature. Consequently laboratory studies were carried out to determine the dissolution rates of potash ore under conditions of natural convection mass transfer from vertical surfaces. The paper summarizes the methods used and the data obtained for the dissolution of potash ore. Both theory and data on the dissolution rates of soluble salts under natural convection conditions are inadequate for industrial purposes and areas of additional research are indicated.
Thermodynamic evaluation of the carbon‐hydrogen system at high temperatures
Authors: Blanchet J. L. , Parent J. R. , Covrtois P. A.
Published: March 2009

A theoretical study of the C‐H system reveals that, at high temperatures, many polymeric species have to be taken into account. Free energy functions of the species involved have been calculated to permit the evaluation of the equilibrium compositions of the system in both the heterogeneous and homogeneous regions. Pressures ranging from 0.1 to 10 atm. and carbon to hydrogen ratios from 0.5 to 20 were investigated between 2,000 and 6,000°K.

Since the reaction of carbon vapor with hydrogen is highly exothermic, a reaction scheme was also developed whereby the endothermic heat of cracking of various hydrocarbons could be balanced by the former reaction. Several conditions related to a global heat of reaction have been considered.
Local resistivity probe for study of point properties of gas‐liquid flows
Authors: Nassos G. P. , Bankoff S. G.
Published: March 2009

In this work a resistivity probe for local property measurements, developed originally(1, 2, 3) for (non‐wetting) mercury‐nitrogen flows, was adapted to a broader class of gas‐liquid flows, such as air‐water. To compensate for the non‐negligible dry‐out time of the probe in aqueous systems, a trigger circuit was installed to sense bubble arrival rapidly. Another problem which was solved was the greater tendency for bubbles in water, as compared to mercury, to deflect away from the probe. The probe signal is an instantaneous record of the arrival and departure of bubbles at any point in the flow, and hence is well‐adapted to auto and cross‐correlation measurements, as well as distribution function studies.
Air flow in a tube with a diverging inlet: II. Measurement and correlation of confirmed fully developed turbulent flow
Authors: Christiansen S. E. , Dallalan I. G.
Published: March 2009

Mean local velocities were measured in the section of a tube where turbulent flow was experimentally confirmed to be fully developed. Over Reynolds numbers from 9,000 to 56,0 00, the velocities correlated, using a logarithmic distribution, almost identically to those of Deissler. Because of the limited data for γ+< 26, no meaningful correlation near the wall was obtained.

Using these data as a basis, a comparison of the various correlations for fully developed turbulent flow in the core region was performed. Although measurements in the laminar sublayers were limited, some discussion of correlations applicable over the entire cross‐section of the tube is included.

Pai's equation, valid from the wall to the center‐line, was found to correlate all of the data best for the several approaches tested. In the turbulent core, the improved universal velocity distribution correlation suggested by Bogue but in simplified form, correlated the data equally well. Using the method of Wasan et al, this logarithmic distribution could be joined without a discontinuity to other suitable correlaions valid near the wall.
Laminar flow in axisymmetric conduits by a rational approach
Authors: Shih F. S.
Published: March 2009

Numerical and closed‐form solutions to laminar flow in regular polygonal conduits, star‐shaped conduits, and rectangular conduits are presented. Results by the present approach are shown to be more accurate and the computation to require less effort than conventional methods. The formal finite‐series solutions obtained through the present approach lend themselves to parametrization and to a judicious choice of computational schemes. In addition both analytical and numerical procedures yield exact solutions to flow in an equilateral and in an elliptic conduit. The present approach proves to be advantageous in its accuracy, generality, and simplicity.
A kinetic study of catalytic butane dehydrogenation
Authors: Noda S. , Hvdgins R. R. , Silveston P. L.
Published: March 2009

A study was made of the dehydrogenation of n‐butane over a commercial chromia‐alumina catalyst. Dehydrogenation runs were performed at 500°C. and space velocity of 34,000 hr−1 over a range of butane partial pressures from 0.06 to 1.80 atm. Conversions were differential, averaging about 3% (with a maximum of 6% ) of the input butane.

Reaction was found to be 0.75 order in butane partial pressure. Thermodynamic equilibrium was attained among the products, which were 1‐butene, cis‐2‐butene, and trans‐2‐butene.

The method of Yang and Hougen showed dehydrogenation to be surface reaction controlled at a confidence level of 91%. This conclusion agrees with that of a previous study by Dodd and Watson.
Direct contact heat: Transfer with change of phase: Evaporation rates in vacuum freezers
Authors: Shiloh K. , Sideman S.
Published: March 2009

The basic factors affecting the rate of evaporation from salt‐water ice slurries in a vacuum freezer were investigated. The interfacial liquid‐phase thermal resistance is governing the evaporation process. The heat transfer coefficient is independent of the temperature driving force up to about 0.7°C., and is strongly affected by mixing and ice concentration. Vapor bubbles, internally generated or entrained, which appear at higher ΔT's increase the dependency of the transfer coefficient on ΔT and decrease the dependency on the mixing rates. Interfacial break‐up greatly increases the transfer rates. The transfer coefficients increase with ice concentration, up to 2 to 5% ice fraction, depending on the mixing rate, then decrease with increased ice fraction due to increased viscosity. Theoretical considerations substantiate the experimental results.
Reactor optimisation problems for reversible exothermic reactions
Authors: Dyson D. C. , Horn F. J. M. , Jackson R. , Schlesinger C. B.
Published: March 2009

Optimization of tubular reactors in which the desired reaction is exothermic and reversible is considered. For the cases where there are no side reactions and there is no decay of catalyst various types of temperature control are investigated. The remaining cases considered are a) stable catalyst, irreversible decay of product and b) decaying catalyst, stable product. In each of these cases perfect indirect temperature control is treated. Particular attention is given to devising numerical methods which take advantage of the structure of the problem in question and to convenient representation of data.
Adaptation of the two‐derivative method of optimisation in cases of non‐convergence
Authors: Methot J. C. , Cholette A.
Published: March 2009

Problems of optimization are often solved readily by means of the Two‐Derivative Method but suitable adaptation is required at times to bring about convergence, as is sometimes the case in the optimization of stage processes.

The nature of the corrective action can be suggested by the physical limitations of the particular problem investigated or by the peculiarities of the function to be optimized. Different adaptation techniques are examplified by various problems: minimum energy requirements for IV compressors in series; optimum solvent distribution between N extractors in series when cross flow takes place, whether the equilibrium relationship is represented by a straight line or by a curve; optimum number of stages in counter‐current extraction, without the need for the construction of a special graph with two families of superposed contour lines.
Solving complex chemical equilibria by a method of nested iterations
Authors: Storey S. H. , Van Zeggeren F.
Published: March 2009

The equilibrium composition of a mixture of molecular species can be obtained by finding the solution of a set of simultaneous non‐linear equations relating the concentrations of these species. Atom balance equations, wherein the species concentrations are related to each other through chemical equilibrium constants, form a many‐variable set of simultaneous non‐linear equations. It is shown how many‐variable problems of this type can be treated as a nested set of single‐variable equations. This treatment allows the use of recent, powerful methods for forcing convergence in single‐variable iterations. The method developed does not require explicit matrix inversion. It is fast and suitable for a small computer. The method has been found particularly useful for routine computations. Up to two non‐gaseous species can conveniently be included. An example is given of the use of the method.
The kinetics and mechanism of the chloride‐chlorate reaction
Authors: Hong C. C. , Lenzi F. , Rapson W. H.
Published: March 2009

The kinetics of the reaction

have been studied at 25°C. in strong acid solution; the effects of acidity, chloride, chlorate and chlorine are reported.

A mechanism is postulated to interpret the peculiar features of this reaction as well as the stoichiometry and some of the kinetics of the parallel reaction

The mechanism involves HClO2 and HOCl as intermediates

General rate expressions are derived for the formation of chlorine dioxide and chlorine, and the individual rate constants are calculated. An expression is obtained for the relationship between the ratio of chlorine dioxide to chlorine produced and the ratio of chlorate to chloride.
Vapor phase reactions of graphite with light hydrocarbons
Authors: Blanchet J. L. , Parent J. R.
Published: March 2009

The pyrolysis of ethane and propane has been performed in the presence of carbon vapor at temperatures between 2,000°K and 5,000°K. This high energy environment is obtained by an electric arc struck between two graphite electrodes. The quenched gases are analyzed by gas chromatography.

The major reaction products are acetylene and hydrogen. C2H2 yields are a function of the C/H2, ratio, the power input, the reaction temperature and the total pressure.

Power levels between 10 and 50 kw. and gas flow rates of 1.5 to 20 liters per minute have been used. The electric arc process of hydrocarbon cracking is compared with conventional methods of acetylene production.
The longitudinal mixing of liquids in bends
Authors: Aunicky Z.
Published: March 2009

The longitudinal mixing of liquids flowing through straight pipes may be characterized by the coefficient of longitudinal dispersion K. In the case of pipings equipped with bends, the value of K must be extended by ΔK expressing the more intense longitudinal mixing in bend areas. Physically, the value of ΔK is determined by the secondary flow in pipe bends.

The dependence of ΔK upon the Reynolds number NR = 15 180‐73 180/, the bend length /α = 30°.90°/ and the proportional bend curvature /R/D = 2‐6/ has been measured on a 50,8 mm ‐ diameter pipe. These dependences are expressed by empirical equations. Each of these partial results is further discussed from the view of relationships valid for secondary flows. The individual values of dependence are summarized in a final equation expressing the simultaneous effect of each observed variable upon the value of ΔK, i. e.
Gamma‐initiated chlorination of methane
Authors: Werezak G. N. , Hodgins J. W.
Published: March 2009

Gamma radiation has been used to initiate the gas phase reaction between chlorine and methane. The products consist of hydrogen chloride, and the four chlorinated methanes, in yields depending on the experimental conditions. Experiments were conducted over a range of temperatures, pressures, concentrations and absorbed doses. G values as high as 1.2 × 106 were found, indicating the formation of a chain reacting system. Two hypothetical reactor models were used to obtain an estimate of the energy cost of the process. On the basis of the reactor models studied, a one‐pass gamma reactor appears uneconomical for the production of carbon tetrachloride, but the energy cost for methyl chloride production is less than one percent of the product value.
A study of stripping uranium complex from an amine extract with aqueous salt solutions
Authors: Jickling R. S. , Diez Gerhard , Van Cleave A. B. , Decovrsey W. J.
Published: March 2009

The organic phase produced by extraction of a uranium leach liquor with Amberlite LA‐2 in kerosene was stripped of uranium in laboratory tests with solutions of NaCl and H2SO4 or solutions of Na2SO4. It was found that NaCI‐H2SO4 stripping reduced considerably the effectiveness of the solvent for subsequent extraction, whereas Na2SO4 stripped the uranium content without any deleterious effect. Optimum Na2SO4 concentration and pH for stripping were determined. Phase separation time and entrainment losses appear satisfactory.
Effect of various parameters on the level of mixing in continuous flow systems
Authors: Cloutier Leonce , Cholette A.
Published: March 2009

Variations of the level of mixing in a flow system have been investigated as a function of the following parameters: diameter, shape and speed of the agitator, feed rate and position of the feed inlet.

At agitator speeds inferior to a critical value, a minimum level of mixing is observed which depends on the position of the feed inlet. At speeds superior to the critical value, the level of mixing increases linearly with agitator speed, at a given feed rate, until conditions of perfect mixing are reached. The critical agitator speed and the position of each straight line depend on the agitator size. A modified Reynolds number makes possible a more general correlation.

At a given agitator speed, superior to the critical value, the level of mixing decreases as the feed rate increases, due to the smaller amount of energy imparted by the agitator per unit mass of feed. The effect of agitator shape on the level of mixing is rather pronounced as it affects the flow patterns inside the reservoir.
Effet du diamètre de l'agitateur et de la largeur des chicanes sur le niveau d'agitation en régime continu et sur la puissance dissipée
Authors: Garceau J. , Cloutier Leonce , Cholette A.
Published: March 2009

Le systéme étudié consiste en un réservoir cylindrique vertical muni d'un agitateur coaxial à turbine et de chicanes. L'entrée de l'alimentation et la sortie de l'effluent se trouvent dans l'axe du réservoir, la première sous l'agitateur et l'autre en surface.

On a utilisé un modèle proposé par Cholette et Cloutier pour caractériser les paramètres de l'agitation. A une vitesse donnée de l'agitateur, la présence de chicanes a pour effet de diminuer le niveau d'agitation. Cette diminution est une fonction complexe de la largeur des chicanes. La présence de chicanes entraǐne également une diminution du court‐circuit.

Le couple varie avec le niveau d'agitation; il augmente en présence de chicanes et encore plus pour de grands diamètres de l'agitateur.

Les auteurs proposent une représentation des différents circuits internes qui permettent d'expliquer les résultats expérimentaux.
Velocity profiles and pumping capacities for turbine type impellers
Authors: Cooper R. G. , Wolf D.
Published: March 2009

Velocity and angle profiles emanated by turbine type impellers were measured in both air and water using a hot wire anemometer probe and two and three dimensional pitot tubes. Pumping capacities were then calculated from the velocity data. The effect of the rotational speed and the dimensions of the turbine was investigated.
Thermal conductivity of simple gases at normal pressures
Authors: Roy Dipak , Thodos George
Published: March 2009

Thermal conductivity measurements available in the literature for simple gases at normal pressures (approximately 1 atmosphere) were used to obtain the productk*λ, where the parameter, λ =M1/2Tc1/6/Pc2/3. Separate relationships betweenk*λ andTRresulted for monatomic, diatomic and triatomic gases.

The relationships for monatomic gases can be expressed as follows

For the diatomic and triatomic gases, linear relationships resulted, when at the same reduced temperatures, theirk*λ values were plotted against (k*λ)mon log‐log coordinates. These relationships can be expressed in equation form as follows

and

Thermal conductivities calculated with these relationships have been compared with experimental values and produce an average deviation of 2.8% for the monatomic gases (219 points), 4.3% for the diatomic gases (282 points) and 4.6% for the triatomic gases (242 points).

In this treatment, helium and hydrogen do not follow the general pattern and consequently these substances have been treated separately.
Nonuniform initiation of photoreactions II. Diffusion of reactive intermediates
Authors: Hill F. B. , Reiss N.
Published: March 2009

The influence of spatially nonuniform initiation is investigated for a class of photoreactions in which diffusion of intermediates is important. The investigation is centered on a differential equation for reaction and diffusion of reactive intermediates. The circumstances are set forth under which the equation is valid for several kinetically similar reaction types. A solution is obtained for Lambert's law attenuation. The characteristics of this solution and the solution obtained by Noyes for linear attenuation are discussed. The practical consequences of these solutions are shown through illustrative calculations based on the photochlorination of tetrachloroethylene.
An equation of state for liquids
Authors: Chaudhari P. Mitra , Mathvr G. P. , Stager R. A.
Published: March 2009

A comparatively simple and accurate equation of state has been developed for the liquid state. The proposed equation has the form

where K and q are constants dependent on temperature. The equation is tested for validity against P‐V‐T data for aldehydes obtained in the course of this investigation. Literature data on alkanes, alcohols, and water were also utilized to confirm the validity of the equation. A critical comparison of the proposed equation with the Hudleston equation reveals the former to yield more satisfactory prediction of P‐V‐T behavior of liquids.
On the pseudo steady state approximation for gas solid reactions
Authors: Luss Dan
Published: March 2009

A method to obtain bounds on the integral and instantaneous rate of diffusion and mass transfer controlled gas solid reactions in spherical particles is developed. It is shown that the pseudo steady approximation is valid during most stages of reaction even under time dependent ambient conditions.
The pipeline flow of paste slugs: Part II. Pressure gradients and velocities of trains of slugs
Authors: Brown R. A. S. , Jensen E. J.
Published: March 2009

Previous studies of the pipeline movement of single paste slugs of coal have been extended to determine the velocities of, and the pressure gradients along, trains of slugs. The measurements were taken in a 70‐foot long, closed‐loop line made from 0.95‐inch bore, rigid plastic tubing. Flow in the line could be switched to maintain continuous movement of a train of slugs.

Tests were made with slugs of 80:20 (w/w) coal‐water paste which was extruded through a 0.775‐inch die and also with slugs which were stabilized by the addition of agar to the water used for making the slugs. Slugs made from coal and agar solution were formed in cylindrical molds having diameters of 0.567, 0.661 and 0.756 inches and were intended to show more clearly the influence of slug diameter on the behavior of the trains. Individual slugs were five inches in length and were formed into trains with lengths of up to fifteen feet for the tests. The oil used as carrier fluid was a light mineral oil (μ = 5.92 cp,σ = 0.826 at 70°F.), which was circulated through the pipeline loop at velocities ranging from 1.0 to 10.0 ft./sec.
The simulation of an existing ethane/dehydrogenation reactor
Authors: Petryschuk W. F. , Johnson A. I.
Published: March 2009

This paper is concerned with the mathematical representation of an existing box‐type furnace for the thermal dehydrogenation of ethane. The furnace is composed of a preheating convection section and a radiant heated section. The two models considering (i) the tube‐side calculation and (ii) the radiant heat transfer in the combustion chamber are independent of each other.

A study is made of the effects of pressure, heat flux level and “steam/hydrocarbon” ratio on the effluent composition. A significant improvement in reactor operation if a more uniform heat flux could be achieved is predicted.

From the radiant heat transfer computations an unexpected variation in flame temperature in the furnace under study was detected.
The kinetics of oxidation of sodium sulphite
Authors: Srivastava R. D. , Mcmillan A. F. , Harris I. J.
Published: March 2009

The kinetics of the reaction of oxygen with sodium sulphite in aqueous solution without and with a catalyst of cobaltous sulphate have been studied by a flow thermal method.

The rate of reaction of oxygen and sodium sulphite was found to be first‐order with respect to oxygen and variable order with respect to sulphite, and the promoting effect of cobaltous catalyst was proportional to its concentration. A reaction mechanism has been proposed and a rate expression derived which is in good agreement with the experimental data.
Effects of turbulence on particulate heat and mass transfer
Authors: Clamen A. , Gauvin W. H.
Published: March 2009

This paper reviews a number of experimental studies concerned with the influence of turbulence on heat and mass transfer from a particle in a fluid medium. Heat and mass transfer rates, as affected by free‐stream turbulence, undoubtedly reflect changes in the ambient flow structure around a body. Attempts have been made, therefore, to relate the established effects of turbulence on the various parts of the flow field around a particle to the variations in heat and mass transfer rates observed for investigations conducted under different conditions. A review has also been made of the effects of periodic oscillations on heat and mass transfer rates in an attempt to provide greater insight into the more complex effects of turbulence.
Solution of reaction and heat flow problems by nonlinear estimation
Authors: Surkan A. J. , Wu C. L.
Published: March 2009

Before the advent of nonlinear optimization algorithms, the solution of chemical reaction or heat transfer equations was attempted primarily by trial and error or linear approximation methods. In the method illustrated by the two examples in this paper, any set of nonlinear equations for a chemical or physical process are replaced by a single equation. The variables of interest are in the resulting functional equation treated as parameters whose optimum values are determined by a nonlinear estimation technique. These values are considered as nonlinear regression coefficients which are simultaneously adjusted by an optimization algorithm. The method gives an estimate of the standard deviation in the determination of the value of each variable and provides information concerning the errors associated with their interaction or pairwise correlations. Validity of the results is confirmed by comparison with solutions independently obtained through a matrix technique developed by Wu (1). For each of the examples the magnitude of computed residual is provided as a measure of the precision of the solution set. The general method is applicable to a very wide class of physical and chemical problems described by one or more nonlinear equations.
Turbulence suppression in solutions and pure liquids
Authors: Oliver D. R. , MacSporran W.
Published: March 2009

Experiments dealing with the onset of turbulent flow in very small capillary tubes are described. The liquids are water, n‐heptane, toluene and four aqueous solutions containing small quantities of a polymeric additive.

The transition from laminar to turbulent flow is delayed in a manner dependent on tube diameter. There is an essential similarity between the behavior of all the liquids. Possible reasons for the observed behavior are discussed and it is suggested that the explanation lies in the presence of varying degrees of elasticity in the liquids used.

Using normal stress data from a jet thrust apparatus, the transition values of various dimensionless groups are evaluated.

The group which gives the most consistent behavior is the inertio‐elastic number equivalent to a Reynolds number in which viscous shear stress is replaced by elastic normal stress.
Calculation of ternary equilibrium vapor compositions from total vapor pressure‐liquid composition data
Authors: Chang Shinn‐Der , Lu Benjamin C.‐Y.
Published: March 2009

A simple and direct method for evaluating ternary vapor‐liquid equilibrium compositions from measurements of the total vapor pressure exerted by the liquid phase along lines of constant liquid mole fraction ratio is presented. Application has been successfully made to the ternary system nitrogen‐argon‐oxygen at 180°r. The proposed method modifies that for binary systems and can be conveniently applied to ternary systems at low to medium pressures.
Laminar and turbulent flow in annuli of unit eccentricity
Authors: Bourne D. E. , Figueiredo O. , Charles M. E.
Published: March 2009

Experimental results are presented for the flow of water in eccentric annuli having unit eccentricity in the laminar, transition and turbulent flow regimes at Reynolds numbers between 200 and 20,000. In both the laminar and turbulent regimes the interesting result is obtained that, for a given Reynolds number, the friction factor is a minimum at a diameter ratio of about 0.750. The experimental results are compared with previous theoretical analyses in the laminar region, and with previous experimental data at Reynolds numbers exceeding 20,000 in the turbulent region. A further interesting result relates to the transition region where, at intermediate diameter ratios, the transition from laminar to turbulent flow becomes more diffuse. This appears to be a consequence of the gradual change from laminar to turbulent flow brought about by the variation in local Reynolds number from zero to a maximum value within the eccentric annulus. It is believed that sufficent experimental data are now available for the pressure gradient to be predicted for flow in eccentric annuli of unit eccentricity over a relatively wide range of Reynolds number.
Heat transfer from teflon‐treated surfaces under flow conditions
Authors: Al‐Shahristani H. , Andrews D. G.
Published: March 2009

The effect of Teflon spot treatment of the heating surface on nucleate boiling under flow conditions has been investigated. This effect is found to be complicated, varying strongly with temperature difference and degree of sub‐cooling. In general, for high degrees of subcooling, there is some improvement in the heat transfer coefficient for Teflon‐treated surfaces at low temperature differences, and an opposite effect at high temperature differences. Teflon spot treatment does not produce any appreciable effect at very low degrees of subcooling. An attempt has been made to explain this complex effect of Teflon treatment, taking into account maximum and minimum bubble diameters and insulating effect of Teflon spots.
Filtration of non‐Newtonian fluids
Authors: Kozicki W. , Tiu C. , Rao A. R. K.
Published: March 2009

Equations of motion characterizing the flow of incompressible, time‐independent non‐Newtonian fluids, exhibiting the anomalous surface effect, through compressible porous media are developed. Approximations are made to arrive at workable filtration equations for slurries of non‐Newtonian (power‐law) fluids. The constant‐pressure and constant‐rate filtration relationships developed are verified experimentally using slurries of calcium carbonate in water and dilute CMC solutions. The anomalous surface effect is found to exist in the filtration of the non‐Newtonian fluids. The specific cake resistance in the case of the non‐Newtonian sludge and the ratio of the effective slip velocity to the pore velocity are found to be functions of both the CMC concentration and the pressure drop across the filter bed.
The mathematical representation of a light hydrocarbon refining network
Authors: Petryschuk W. F. , Johnson A. I.
Published: March 2009

The block‐relaxation method, system‐tH equations and a direct sequential calculation have been combined to solve the non‐linear algebraic equations describing the steady‐state behavior of a multi‐recycle network of five distillation towers and two reactors. Approximately 2,000 such equations are solved in 30 minutes of IBM 7040 computation time.

The existence of optimum tolerances on individual column calculations and on individual recycle calculations is demonstrated. The application of the block‐relaxation method to a network of distillation columns is numerically shown to simultaneously converge the network equations and the individual column equations to the final solution.
Time sub‐optimal control of the gas absorber
Authors: Chant V. G. , Luus R.
Published: March 2009

Proper choice of the weighting matrix Q in the Liapunov function V = x' Q x followed by the minimization of the forward difference δV gives sub‐optimal control which can come close to the time optimal control. Several methods of determining such a weighting matrix are presented and these methods are compared and evaluated with respect to a six‐plate gas absorber. The choice of the sampling time for the discrete‐time model is very important, and its effects on the best weighting matrix and the resulting control policy are illustrated. The results of this investigation yield an efficient iteration algorithm whereby Q is successively improved until the sub‐optimal control policy approaches the time optimal control.
A test of the withdrawal theory for ellis fluids
Authors: Hildebrand Richard E. , Tallmadge John A.
Published: March 2009

The Ellis withdrawal theory is shown to be a eubstantial improvement for predicting film thickness as compared to the previous theory for pseudo‐plastic fluids. The two‐term Ellis power‐law theory ie shown to be a good approximation to the Ellis theory. The relative deviations between data and Ellis theory become larger at lower speeds.
An investigation into the stability of enclosed laminar diffusion flames
Authors: Deckker B. E. L. , Srinivas R. A.
Published: March 2009

Experiments on enclosed laminar diffusion flames have revealed the existence of a critical relative velocity of air and fuel which is associated with the threshold of low frequency flame vibration. Starting from the hypothesis that these vibrations are triggered by a selectively amplified disturbance arising in the free shear layers near the base of the flame, the authors have obtained evidence of the nature of the disturbance. Further systematic experiments have enabled them to account for the observed behavior of low frequency vibrating diffusion flames in the light of their hypothesis and in relation to the acoustical properties of their combustion system.
Diffusion‐controlled adsorption processes
Authors: Anderson R. B. , Hamielec A. E. , Stifel G. R.
Published: March 2009

Numerical solutions of differential equations for diffusion‐controlled adsorption processes in spherical particles are presented for slow diffusion of gaseous molecules followed by rapid adsorption according to the Langmuir isotherm. As the parameter in the denominator of the Langmuir equation is increased the rate increases and the generalized rate curves shift progressively from that for the linear isotherm, the Langmuir parameter = 0, to the curve of the parabolic law. Adsorption and desorption cycles are considered and parameters are provided for relating any of these processes to the generalized curves. A simple linear equation was shown to approximate the rate curves with moderate accuracy.
Qualitative and quantitative observations on the tubular reactor
Authors: Amundson Neal R. , Luss Dan
Published: March 2009

The tubular reactor in the steady state is considered for a single chemical reaction. It is shown that almost all of the qualitative features of the temperature and concentration profiles may be deduced from the equations themselves without solving them. Extensive numerical calculations are also presented both for the finite and semi‐infinite reactor. Comparisons are made with the lumped constant system. It is shown that the solution for the semi‐infinite reactor is always unique and serves as a bounding solution for all finite reactors with the same parameters.
Hydrogen reduction of chromium chlorides: A kinetic investigation
Authors: Rigg Tyson , Innes David B. K.
Published: March 2009

The reduction of single pellets of chromic and chromous chlorides by hydrogen has been studied kinetically. The reaction 2 CrCL3 + H2 →2 HCl + 2 CrCl2 was investigated over the temperature range 475−615°C. The rate controlling factor in the range of 475−493°C. is vaporization of chromic chloride; the activation energy was found to be 67.8 K.cal./mole. Between S10 and 615°C, the reaction rate is evidently controlled by heat and internal mass transfer processes. In this case the apparent activation energy is 16.6 K.cal./mole.

Reduction of chromous chloride, CrCl2 + H2 → 2 HCl + Cr, was investigated over the temperature range 675−800°C. This reaction is also controlled by heat and mass transfer and involves vaporization of the chromous chloride. The apparent activation energy is 25.5 K.cal./mole.
Extractive metallurgy at international nickel — A half century of progress
Authors: Renzoni L. S.
Published: March 2009

The R. S. Jane Memorial Lecture Award was established to commemorate the memory of the late Dr. Robert Stephen Jane who made an outstanding contribution to the chemical profession and the chemical industry in Canada. It is presented to a resident of Canada for exceptional achievement in the field of chemical engineering or industrial chemistry. The Lecture is presented at the annual C.I.C. Canadian Chemical Engineering Conference. Mr. Renzoni, recipient for 1968, presented this paper at the 1968 Tripartite Chemical Engineering Conference, September 22–25, 1968, in Montreal, Quebec.
Sedimentation of two prolate spheroids in close proximity
Authors: Hnatow M. , Pfeffer R. , Happel J.
Published: March 2009

Experiments concerned with the rate of fall of two prolate spheroids (needle‐like objects) in close proximity to each other are described in this paper. Quantitative agreement with S. Wakiya's theoretical predictions is obtained for the case in which two prolate spheroids are settling, one above the other, in the direction perpendicular to their axis of symmetry and for the case in which two prolate spheroids are settling end to end in the same horizontal plane in the direction perpendicular to their axis of symmetry.

These experiments and this theoretical treatment apply only in the creeping motion region. At higher velocities, inertial effects would become significant.
Interfacial effects for transient heat conduction in the non‐continuum regime
Authors: Picot J. J. C.
Published: March 2009

Experimental results are given which show that for non‐continuum conditions for heat conduction between a solid surface and a gas, there is a surface zone (of probably four or five mean free paths in thickness) where the “effective” thermal conductivity gradually changes from a value governed by gas — solid wall interactions to the normal continuum value in the bulk phase. In the temperature‐jump range, the effect of this surface zone in steady‐state situations can be adequately expressed by a temperature‐jump distance, but this approach is inadequate for transient state situations. In the transient state, a theory is required which allows for the gradually changing effective thermal conductivity in the surface zone.
Simultaneous heat and mass transfer through laminar boundary layers in combined forced and free convection
Authors: Barton H. J. , Trass Olev
Published: March 2009

Heat and mass transfer rates from a vertical plate are reported for combined free and forced convection. Heat transfer coefficients were obtained from temperature gradients at the wall and mass transfer rates from thickness decrease measurements of naphthalene coatings.

The free convection data cover a Grashof number range from 100 to 2 × 108 and the combined flow parameters Gr/Re2 and Gr'/Re2 vary from 0.2 to 100 and 2 × 10−8 to 3.25, respectively. Predictions from boundary layer solutions are in good agreement with the data.

Absorption of ultraviolet light by naphthalene vapor was used to measure free convection concentration profiles. Results prove the versatility of this method.
Simultaneous heat and mass transfer from a single sphere to a turbulent air stream
Authors: Boulos Maher I. , Pei David C. T.
Published: March 2009

A study of the simultaneous heat and mass transfer from a single sphere to a turbulent air stream has been made. The aim of the investigation is to evaluate the effect of mass transfer on the rate of heat transfer. Results are compared with pure heat transfer data under similar conditions as well as those obtained by the evaporation of liquids from porous spheres.