bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydroxylamine production by electroreduction of nitric oxide in a trickle bed cell
Authors: Bathia M. L. , Watkinson A. P.
Published: March 2009

Hydroxylamine was produced in a trickle bed cell by passing nitric oxide gas and sulphuric acid catholyte co‐currently downward through a cathode bed of tungsten carbide particles. The dependence of hydroxylamine concentration and current efficiency on cathode activity and particle size, flow rate and composition of gas and catholyte, bed height, and reactor temperature and pressure are reported. Hydroxylamine concentrations of up to 0.18 mol/L were produced at 62% current efficiency in a single pass through a 0.375 m high cell operated at atmospheric pressure and a current density of 213 A/m2. The hydroxylamine concentration increased with cell pressure, gas flow rate and decreases in catholyte flow and could be raised to 0.4 mol/L by recycling the catholyte. The process appears to be controlled by mass transfer at current densities over 400 A/m2 and by electrochemical reaction below about 300 A/m2.
Catalyst decay in the kinetics of methylcyclohexane dehydrogenation over Pt‐NaY zeolite
Authors: Corma A. , Cid R. , Agudo A. Lopez
Published: March 2009

The kinetics of the dehydrogenation of methylcyclohexane to toluene over platinum on NaY zeolite have been studied at 390°C and atmospheric pressure. Cumulative conversion data obtained at constant space velocity and various reaction times on stream was treated using the “Time on Stream” theory. In this way the rate constants for both dehydrogenation and catalyst decay have been determined.

The reaction has been shown to occur via a series of consecutive partial dehydrogenations, with the first dehydrogenation as the rate controlling step. The influence of the partially dehydrogenated products as well as the influence of the toluene, on the deactivation of the catalyst is discussed.
Steady pressure driven two‐phase stratified laminar flow through a pipe
Authors: Ranger K. B. , Davis A. M. J.
Published: March 2009

The two phase pressure driven flow in a circular pipe in which the interface occupies an arbitrary horizontal position has, as shown by earlier authors, an explicit analytical solution in which the velocities are expressed as Fourier integrals. Here this is used to express the volumetric fluxes of each fluid as one‐variable integrals whose values can be easily computed. The results agree with those obtained by Gemmell and Epstein by numerical integration of the differential equations.
The simulation of turbulent mixing with simultaneous reaction of miscible reactant streams
Authors: Radford R. D. , Harris I. J.
Published: March 2009

The use of stochastic models to predict chemical conversion in turbulent tubular reactors with separate but miscible reaction feed streams has been limited by the inefficiency of the computational processes. This is despite the advantages of the stochastic approach when compared to the more popular diffusional based techniques. Mathematic analysis of the stochastic process leading to direct algabraic representation of the stochastic model is presented which considerably reduces the computational time requirement of the stochastic approach.
Conjugated heat transfer to laminar flow with internal heat source in a parallel plate channel
Authors: Mori Shigeru , Kawamura Yuhji , Tanimoto Akira
Published: March 2009

A steady heat transfer problem was analyzed as a conjugated problem between a fully‐established laminar flow and the duct wall, under two kinds of boundary conditions at the outer wall surface. The internal heat generation is described as a linear function of the fluid temperature.

The influence of the heat conduction in the wall was found to be important for the case with small wall conductance under a boundary condition of the first kind, and also for the large wall‐conductance case under the second condition. Such influence is more significant for the case with an internal heat source.
A comparison of methods used to measure pore size in solids
Authors: Ternan M. , Fuller O. M.
Published: March 2009

The size of pores in a number of solid samples has been measured by nitrogen adsorption, oxygen adsorption, mercury porosimetry, scanning electron microscopy, and optical microscopy. All the pores in each of the solid samples investigated were straight, had a circular cross‐section, and had similar dimensions. By assuming the existence of contact angle hysteresis, agreement between the microscopy pore radii and mercury porosinietry radii measured both from penetration and from retraction was obtained. Dimensional changes in the solid may have contributed to the pore radii determined by nitrogen adsorption and oxygen adsorption being larger than the radii determined by microscopy.
Optimization of design and operating policy of an industrial two‐bed co‐shift reactor
Authors: Sterckx L. M. , Van Rompay P. V.
Published: March 2009

The optimal operating policy for a two‐bed adiabatic CO‐converter is computed using the Discrete Maximum Principle. The problem is then extended to determine also the optimal design of the system. A sensitivity analysis of the optimal solutions is presented, showing the influence of the principal process parameters. Economical, chemical and physical data have been obtained from an existing CO‐converter in a standard 1000 short Tons/day NH3 plant.
Particle deposition on a single spherical collector a three‐dimensional trajectory calculation
Authors: Beizaie Masoud , Tien Chi
Published: March 2009

Aerosol deposition from a flowing stream onto a single spherical collector with gravitational force acting transverse to the direction of flow was studied. The effects of inertial impaction, gravitation, interception and electrostatic forces were examined. In contrast to the case where gravitational force acts along the direction of the flow, the particle trajectories are not axisymmetrical and the trajectory equations are three‐dimensional. The formulation and numerical solutions of such equations represent the main task of this work.
Drag coefficient of relatively contaminated gas bubbles
Authors: Ishii Tsutomu , Pei David C. T.
Published: March 2009

Based on the velocity profiles around clean and relatively contaminated gas bubbles, the tangential and normal stress, pressure distribution at the surface around the gas bubbles, and finally the viscous, form and total drag coefficient of the gas bubbles were calculated and compared with experimental values for dilute aqueous solutions of alcohols. The theory verifies the experimental observation that the total drag coefficient of single gas bubbbles increases with the contamination factor. The effect of the void fraction of the gas bubble swarm on the total drag coefficient was examined by the use of a void function. Most of the void functions for the relatively contaminated gas bubble swarms were between the values of potential flow and that of solid spheres.
Continuous emulsion polymerization of vinyl acetate. Part: II Parameter estimation and simulation studies
Authors: Kiparissides C. , Macgregor J. F. , Hamielec A. E.
Published: March 2009

Conversion data obtained over a wide range of operation of a continuous latex reactor for vinyl acetate polymerization were used to estimate the unknown kinetic parameters of a transient CSTR reactor model. Conversion‐time histories were adequately fitted by models of two levels of sophistication: a comprehensive model which solves for the age distribution function of polymer particles, and a simplified model that neglects the effect of particle size distribution for the case of continuous particle nucleation. These models were then used for simulation and control studies in an attempt to devise a practical control strategy(11). The existence of sustained oscillations was investigated by examining the behavior of the state variables in the phase‐plane.
Oxidation of low concentrations of hydrogen sulfide over activated carbon
Authors: Coskun I. , Tollefson E. L.
Published: March 2009

The oxidation of low concentrations of hydrogen sulfide with air over activated carbon was studied over the temperature range 24‐200°C using both fixed and fluid bed reactors. The predominant reaction, H2S + ½ Oa → H2O + S, was found to have an order of 0.5 with respect of H2S concentration. Activity of the catalyst decreased as the amount of sulfur deposited on it increased. Indirect evidence suggests that adsorption of water by the carbon also decreases its activity as a catalyst at lower temperatures. Values of the activation energy and the frequency factor were determined for various sulfur loadings using the fixed bed reaction system. Regeneration of the carbon loaded with sulfur was studied at temperatures between 150 and 500°C using steam as a carrier gas. Bright yellow sulfur was recovered. The regenerated carbon was shown to have its original activity.
Direct coking of athabasca tar sand
Authors: Filby J. E. , Flynn P. C. , Goldman J. M.
Published: March 2009

Yield patterns and product quality have been determined for the direct coking of Athabasca tar sand. Temperature and vapor residence time are the key variables affecting yield; tar sand residence time has a minor impact in yield provided that a minimum contact time is achieved. Yields are not sensitive to the composition of tar sand feed. Yields from direct coking are similar to those from commercial bitumen coking processes; previously reported variations in direct coking yields can be reconciled when liquid product endpoint and coking severity are considered.

Coke deposited on the sand is readily burned, producing a flue gas high in SO2 and particulates, and a free‐flowing sand. The sand settles readily from a slurry and disposal presents no obvious environmental concerns.
Coal gasification in a spouted bed
Authors: Foong S. K. , Lim C. J. , Watkinson A. P.
Published: March 2009

Low Btu gas has been produced by gasifying coal in a spouted bed reactor. Coal of size 0.8‐3.6 mm is fed continuously to a 0.15 m diameter spouted bed of inerts and gasified using mixtures of steam and air. Tests of the process with Western Canadian coals of free swelling index 0, 4 and 7 are reported. Gases of heating value to 3.61 MJ/m3 were produced at coal throughputs of 0.188 kg/m2s with the reactor operating at atmospheric pressure and temperatures to 930°C. Characteristics of the spouted bed gasifier are presented and results compared to commercial moving and fluidized bed systems. A simple mathematical model based on the two‐region spouted bed model of Mathur and Lim is used to predict the effect on steam utilization of bed composition, bed height and diameter, and particle size.
Rigorous design of high pressure natural gas pipelines using bwr equation of state
Authors: Moore R. G. , Bishnoi P. R. , Donnelly J. K.
Published: March 2009

A model is presented for the prediction of pressure and temperature profiles in a high pressure gas pipeline. Using the BWR equation of state to predict the properties of the gas, an analytical approach reduces the problem to two nonlinear equations which can be solved numerically. Rigorous thermodynamic treatment of the energy and flow equations results in a model which yields good agreement with published data for high pressure natural gas pipelines. The model is also shown to predict frictional heating during the adiabatic flow of dense phase hydrocarbons.
Sedimentation of droplet dispersions in counter—current spray columns
Authors: Kumar A. , Vohra D. K. , Hartland S.
Published: March 2009

A simple model is presented for the prediction of hold‐up and slip velocity in spray columns in which the continuous phase moves counter‐current to the dispersed phase. Analysis of 591 data points for 16 systems from 8 different sources show that the slip velocity is given in terms of the average drop diameter of the drop swarm and the physical properties of the system by:

for 7 < Re < 2450 and 0.01 < ϵd < 0.75. This equation predicts the slip velocity to within 10% for 70% of the data points and to within 20% for 92% of the data points.
Transferts thermiques entre un serpentin et des fluides newtoniens ou non—newtoniens agités par une turbine à pales inclinées dans une cuve
Authors: Desplanches Herve , Llinas J. Richard , Chevalier Jean‐Louis
Published: March 2009

Le travail présenté concerne le transfert thermique entre un septentin hélicoïdal et des liquides newtoniens, ou non‐new‐toniens agités par une turbine à 4 pales inclinées dans une cuve cylindrique.

La viscosité effective des fluides rhéofluidisants est définie par le modèle de Metzner‐Otto combiné à l'équation rhéolo‐gique d'Ellis. Le transfert thermique dans les fluides newtoniens en régime turbulent est représenté avec la meilleure précision par les équations:

Dans le domaine non‐newtonien, en pompage bas, l'équation ci‐dessous permet une estimation très précise du coefficient d'échange thermique en régime d'établissement
Experimental studies of a consecutive—competitive reaction in steady state and forced periodic CSTRs
Authors: Lee C. K. , Yeung S. Y. S. , Bailey J. E.
Published: March 2009

Experimental studies of diethyl adipate saponification in a CSTR show that forced cycling of feed composition produces significant yield increases in intermediate product relative to the optimal steady state operation, while forced temperature cycling has much less effect. Related experiments provide useful transient heat transfer data for this system. Reaction kinetics have been determined in water and in a 50% (v/v) isopropanol solvent.
The nature of the active sites in the catalytic cracking of gas—oil
Authors: Borodzinski A. , Corma A. , Wojciechowski B. W.
Published: March 2009

The kinetics of gasoil cracking over an HY zeolite catalyst have been studied at atmospheric pressure and temperatures of 482°, 503° and 524°C, using a fixedbed integral reactor. The total conversion of gas‐oil, the yield of gasoline, of various gaseous products, and the influence of temperature on conversion, gasoline and minor product yield are presented here.

The various primary reaction rate constants, the constants describing the decay of catalyst activity, and the refractoriness of the feed, have been determined for this system and are compared with those obtained using a LaY zeolite catalyst. The observed differences between these two catalysts are discussed in terms of the nature and number of active sites present on the two catalysts.

We conclude that the initial reaction of a saturated gas‐oil feed occurs on a range of Lewis acid sites of various strengths. Such sites are more numerous on LaY than on HY, and this disparity is larger for weak sites than it is for strong sites.
Gasification reactions of chars and modified chars produced from jack pine bark
Authors: Ross Robert A. , Fikis David V.
Published: March 2009

Chars produced from locally grown jack pine have been gasified at atmospheric pressure with temperatures up to 650°C in a flow reactor. The gases produced were CO, CO2, CH4 and H2 as well as H2 O. Above the char preparation temperature, 350°C, the yields of gaseous products increased with temperature until 550−600°C when the production of CH4, CO and H2 O decreased. Chars modified by the separate inclusion of 1% w/w sodium borate, sodium phosphate and nickel oxide produced changes in the product distribution; an effect which was also studied during the addition of steam to the gasification cycles. Gross calorific values of the chars and allied materials were determined in an adiabatic bomb calorimeter and residues were analysed for C, H and N contents.
Caractérisation de la tourbe pour le traitement des eaux usées d'abattoirs
Authors: Gravelle Denis V. , Landreville Alain
Published: March 2009

Face à la nécessité de trouver un procédé efficace pour le traitement des eaux usées d'abattoirs, une étude fut menée dans le but d'utiliser la tourbe de sphaigne comme agent d'épuration. Des essais de sorption à l'équilibre et en mode continu à l'aide de solutions synthétiques et industrielles confirment que toute modification chimique apportée à la tourbe n'améliore pas le rendement de celle‐ci face à la retenue des substances organiques retrouvées dans ces eaux. Cette étude vise à identifier les caractéristiques permettant de réduire la concentration des substances organiques au même ordre de grandeur que celle que l'on retrouve dans une eau usée domestique. Les essais en continu, sur des unités pilotes à lit fixe et à lit mobile, démontrent que la tourbe naturelle peut diminuer de façon appréciable la demande totale en oxygène des eaux usées d'abattoirs.
Biodegradation of high—yield spent bisulfite pulping liquor in two volume‐varied chemostats in series
Authors: Lo S. N. , Valade J. L.
Published: March 2009

Spent liquor from industrial high‐yield bisulfite pulping was biodegiaded in a 20‐litre reactor system consisting of two unequal chemostats in series. The purpose was to study, for a fixed total volume, the variation of the overall biodégradation performance with the volume ratio of the first chemostat to the system, especially focusing on the occurrence of maximal % BOD5 removal.

Values of kinetic parameters (substrate removal rate constant, coefficients of decay and growth, and non‐biodegradable matter in feed) obtained for each chemostat were found to be different. Overall % BOD5 removals were 62 to 73 for the operating conditions studied; the maximum occurred at a volume ratio equal to 0.8. Experimental findings agreed very well with calculated theoretical values. In both chemostats, experimental % BOD5 removal decreased linearly as BOD5 loading increased. Excellent correlation existed between % removals of BOD5 and carbohydrates.
Dynamics of a trickle—bed hydrocracker with a quenching system
Authors: Yan T. Y.
Published: March 2009

A mathematical model has been developed to simulate the dynamic behavior of a trickle‐bed hydrocracker without and with one quench. The model was used to study the effects of parameters on transient temperature and hydrocarbon feed profiles. The system was found to be very sensitive to inlet temperatures and the states of catalyst activity.

The model can be used to guide design and operation of a quenching system, i.e., proper location, starting time, and quantity of quench stream, to prevent excess temperature rise that would otherwise lead to “run‐away” condition and poor product yields.
The onset of droplet entrainment in annular downward flows
Authors: Andreussi Paolo
Published: March 2009

The point of onset of large disturbance waves and droplet entrapment has been determined for the annular downward flow of air‐water mixtures in a 24 mm ID tube.

Experimental results are in a good qualitative agreement with the previous work by Webb and Hewitt1. These results indicate that

the critical gas velocity at the onset of entrainment is lower than the value predicted by available correlations

the critical gas velocity continuously decreases at increasing the liquid Reynolds number

below a liquid Reynolds number of 270 no entrainment occurs even at gas velocities as high as 80 m/sec

A correlation for the critical gas velocity which is based on a simple physical model of atomization, is also proposed.
An experimental study on solid‐liquid flow through rectangular ducts
Authors: Prasad Nawal K. , Chand Prem , Mirajgaokar A. G.
Published: March 2009

Reduction in energy consumption has been the main concern of the workers in the field of solid‐liquid flow. Investigators have tried to achieve this objective in various ways. Two of the well‐known methods are: the addition of polymer solutions to the solid‐liquid mixture and the fitting of helical ribs inside regular circular pipes. In the latter case, the reduction is considerable, but it results in a very low rate of transportation. Chiu and Seman have reported considerable reduction of head loss in a square duct when compared to the flow through a circular pipe.

In the present work, an experimental study has been underaken to compare the head loss for solid‐liquid flow in a circular pipe, with that for rectangular ducts of four different aspects ratios (width/height ratios), keeping the cross‐sectional area of each one of them to be the same. When the perforance of a circular pipe is compared with that of the other rectangular ducts, it seems that the square duct shows a better performance in the low operating range of velocity, whereas the rectangular duct of aspect ratio 1.5 presents a still better performance, from the energy requirement point of view, for practically the entire velocity‐range within which the experiment was conducted.
Terminal velocity of porous spheres
Authors: Masliyah Jacob H. , Polikar Marcel
Published: March 2009

Terminal velocity of porous spheres was experimentally measured for a Reynolds number range of 0.2 to 120 for a

normalized sphere radius, β = R/R of 15.6 to 33, where R and k are the sphere radius and permeability, respectively. The drag coefficient for 15 < β < 33 was found to be CD = 24Ω/Re [1 + 0.1315 Re(0.82 ‐ 0.05w)] for 0.1 < Re ≤ 7 and CD = 24Ω/Re [1 + 0.0853 Re(1.093 ‐ 0.105w)] for 7 < Re < 120 with w = log10Re where Re is the sphere Reynolds number and Ω=2β2 [1 ‐ (tanh β/β)] / 2β2 + 3[1 ‐ tanh β/β)]

At high Reynolds numbers, it was found that the porous sphere terminal velocity was less affected by the container walls than for the case of an impermeable sphere. However, at very low Reynolds numbers, the wall effects were found to be similar for both the permeable and the impermeable spheres.
Heat transfer of evaporating droplet flow in low pressure systems
Authors: Rane Anil , Yao Shi‐Chune
Published: March 2009

Convective heat transfer of laminar droplet flow is analyzed for a low pressure system, where latent heat of evaporation and ratio of liquid density to vapor density is high (for example, water at l atm). The droplet size is considered to be approximately constant but the vapor velocity is considered increasing along the tube. The heat transfer effect of droplets in the vapor stream is treated as distributed heat sink. Results are presented in non‐dimensional form for circular tubes, with constant wall heat flux or constant wall temperature boundary conditions. Distinct heat transfer behavior of droplet flow is revealed.
Decomposition of t‐butyl acetate on charcoal and comparison with isomers on charcoal and in the gas phase
Authors: Pettit Paul J. , Anderson Robert B.
Published: March 2009

The decomposition of t‐butyl acetate on charcoal to isobutene and acetic acid is a clean, zero‐ordet reaction at temperatures of 151° to 288°C with an apparent activation energy of 90.8 kJ/mol. The rates for the 4 butyl acetates on charcoal and in the gas phase are compared. The rates on charcoal are always larger than those in the gas phase. The primary reaction products from the decomposition on charcoal and in the gas phase are acetic acid and the butene indicated by the six‐center‐ring mechanism.
Pitch and petroleum coke additions to coke oven charges
Authors: Price J. T. , Gransden J. F. , Leeder W. R.
Published: March 2009

Several pitch materials and a petroleum coke were added to coke oven charges in an attempt to make good metallurgical coke from Canadian coal of poor coking quality. Coal and petroleum pitches were added to a low fluid western Canadian coal of medium volatile bituminous rank, and the blends coked in a technical‐scale moveable wall test oven having a 230‐kg charge capacity. Pitches improved coke tumble test indices, the principal coke quality parameter related to blast furnace performance. Varying levels of petroleum coke were added to an eastern Canadian coal of high volatile bituminous rank, and the blends, some partially briquetted, were carbonized in a test oven. Tumble indices of coke from the partially briquetted charges approached an acceptable level. These investigations confirm that petroleum products as well as coal derivative can play a useful part in the production of a metallurgical strength coke from poor or non‐coking coals.
The use of krasovskii's stability technique for control strategy evaluation and system design
Authors: Lee P. L. , Newell R. B.
Published: March 2009

Krasovskii's stability method for generating Lyapunov functions for the prediction of regions of asymptotic stability (RAS) is applied to a second‐order chemical reaction in an adiabatic CSTR. Three conclusions are drawn from this study. Firstly, that the stability areas predicted by the method are too conservative for use as criteria for control system design. Secondly, that the method fails to predict valid regions of asymptotic stability under some circumstances. Thirdly the results are shown to be sensitive to changes in system parameter values.
Two phase flow in a climbing‐film evaporator
Authors: Tang C. L.
Published: March 2009

The climbing film flow is modelled on a hydrodynaniic and heat transfer basis taking into account the boiling point elevation due to increased liquid solute concentration along the evaporator tube. Some experimental data are compared with the prediction of the model.
A new theoretical formula for turbulent heat and mass transfer with gases or liquids in tube flow
Authors: Sandall O. C. , Hanna O. T. , Mazet P. R.
Published: March 2009

A new theoretically‐based formula is presented for fully developed steady‐state forced convection heat or mass transfer in turbulent tube flow. This relationship, which is proposed for the frill range range of Prandtl or Schmidt numbers between 0.7 (gases) and 100 000 (liquids), is as follows:

Coniparisons a with widely quotcd sets of data show very good agreement IFriend and metzner (heat transfer in liquids), Dcisser and Eian (heat transfer in air), Allen aid Eckert (heat transfer in water), Malina and Sparrow (heat trniisfcr in liquids), Harrott and Hamilton (mass transfcr in liquids)]. Absolute mean deviations vary from 3.6 to 8.1% over the range 0.73 + Pr or Sr ≤ 97 600.
An analytical model for the combustion of coal particles
Authors: Shadman Farhang , Cavendish James C.
Published: March 2009

A model for the combustion of coal particles is developed which accounts for the gasification and pyrolysis reactions throughout the particles, oxidation reactions at the particles' outer surface, distributed gas‐phase reactions around the particles, and transport of heat and mass throughout the reaction zones. The model shows that the combustion of large particles is dominated by gasification and gas‐phase reactions. As large particles burn and shrink, however, the mechanism changes to one dominated by surface oxidation. This change in mechanism can be gradual or very rapid (even discontinuous) depending on the combustion conditions. The particle size at which this transition takes place decreases as the bulk gas temperature or oxygen concentration increase. The proposed model is used to predict the conversion of pulverized coal as a function of time; the results agree with literature data for particles of 26‐32 μm radius.
Determination of the heat of some aerobic fermentations
Authors: Luong J. H. T. , Volesky B.
Published: March 2009

An accurate technique has been developed and applied to continuous measuring of the rate of heat production during a fermentation process. A special temperature control system was developed and used to monitor the heat quantity. The results were corrected for heat losses and gains based on the overall heat balance on the fermentor. The technique was used for precisely determining the rate of heat evolution of Aspergillus niger, Escherichia coli, Candida Upolytica, Candida intermedia and Candida utilis grown on etlianol and different carbohydrate and hydrocarbon sources.

Based on the experimental data, a correlation between the rate of heat released and the rate of oxygen consumed has been determined as Qterm = 0.465 MJ/mol O2 · Δ02. The total heat released also correlated well with the total oxygen consumed by the growing culture. The proportionality constant for this correlation was 0.461 MJ/mol O2. The experimental results agreed well with the theoretical predictions and with those developed by the dynamic calorimetric technique.

The derived correlations reported in this study arc useful for fermentation process design, optimization and control as well as indicators of microbial metabolic activity.
Electrolysis in a pilot‐plant size cell using inclined electrodes and non‐uniform magnetic fields
Authors: Ismail M. I. , Fahidy T. Z.
Published: March 2009

The effect of the inclination angle between opposite electrodes, and between parallel electrodes and the vertical and the horizontal axis, on natural convectivc ionic mass transfer and deposition pattern at inclined vertical plate electrodes was studied in a pilot‐plant scale magneoelectrolytic reactor. The non‐uniform magnetic field with a maximum gradient at the centre of the reactor was generated by means of solenoid winding of water‐cooled copper pipes and high‐current cables. Copper was deposited from an aqueous solution of cupric sulfate and at ambient temperatures on a stainless steel cathode placed at various angles in the horizontal and vertical direction with respect to a stainless steel anode of identical size. Mass transfer rates, inclination angle and bubble pattern are strongly interrelated. The rate of gas generation at both electrodes as well as induced magnetohydrodynamic turbulence determine the extent of locally strong mixing in the cell. The extent and position of cathode oxide formation, due to anodically generated oxygen is influenced by the distribution of the magnetic and the electric field in the cell.
Liquid flow over a rotating dip coater
Authors: Nigam K. D. P. , Esmail M. N.
Published: March 2009

The hydrodynamics of a Newtonian fluid entrained from a stagnant pool by a rotating, partially immersed horizontal cylinder is considered. A numerical solution, based on the Galerkin method of weighted residuals, predicts the film thickness variation over the cylinder surface. The results are compared with experimental measurements and theoretical predictions available in literature. The comparison with the experimental data is good, especially for high capillary numbers. This supports the claim that inertia effects are better depicted in a nonlinear treatment of the problem. The computational procedure applied is not complicated, and may be used for industrial predictions.
The relevance of “HLB” to de‐emulsification of a mixture of heavy oil, water and clay
Authors: Cooper David G. , Zajic J. E. , Cannel Edward J. , Wood Joan W.
Published: March 2009

Series of synthetic neutral surfactants have been used to break emulsions of heavy oil, water and clay. The degree of de‐emulsification was found to correlate with the hydrophilic‐lipophilic balance (HLB) of the surfactant. The most effective agents for de‐watering had HLB values between either 4 and 6 or 13 and 15. For clay removal, the most useful surfactants had HLB values above 20. Surfactants between 5 and 8 were also effective for removing clay, but the material released had appreciably more oil adhering than that removed by the higher HLB compounds. Other surfactant parameters such as surface tension, interfacial tension against hexadecane and spreading tension were unrelated to de‐emulsifying ability.
Transient behavior of the oxidation of propylene over a modified silver oxide
Authors: Kobayashi Masayoshi
Published: March 2009

The oxidation of propylene over a silver oxide containing sodium chloride and sodium hydrogensulfate has been studied by using a transient response method at temperatures ranging from 150 to 175°C. An overshoot behavior for the transient response of propylene oxide indicates the mechanism of Eley‐Rideal type with a rapid desorption of propylene oxide and a slow regeneration of surface oxygen. The activation energy estimated at the transient state was 58.6 kJ/mol.

A characteristic S‐shape mode for the transient response of carbon dioxide reveals the presence of a stable intermediate (In). The (In) can produce equimolar amounts of H2O and CO2 by the reaction with oxygen without producing propylene oxide, indicating that the ratio of C:H in the structure of (In) is 1:2. The amount of (In) estimated under the steady state of reaction is a linear relation to the rate of CO2 formation. The estimated apparent rate constant for the formation of CO2 is in good agreement with that for (In) decomposition estimated from the transient response curves of (In) decomposition. From this agreement, it is concluded that the (In) is a reaction intermediate through which carbon dioxide and water are produced.
Simulating the effects of mixing on the performance of unpremixed flow chemical reactors
Authors: Ritchie Ben. W.
Published: March 2009

A parallel three environment model is developed to describe the effects of incomplete mixing on the performance of continuous flow chemical reactors fed separately by feedstreams which may have arbitrary flowrate and arbitrary residence time distribution. Unpremixed reactants are assumed to first enter partially segregated entering environments and subsequently transfer to partially mixed leaving environments at a rate and in amounts defined by an environment transfer function. Mixing in the environments is stimulated stochastically by Monte Carlo techniques. Calculations based on a kinetic model of the Michaelis‐Menten type for arbitrarily selected pairs of residence time distributions suggest that performance is strongly influenced by the degree of overlap of the distributions and the method of feeding the reactants. The model is shown to compare directly with published experimental data obtained from a “jet‐stirred” reactor and an equivalence found between the models' parameters and those of previously developed micromixing models.
Prediction of the viscosity of mixed electrolyte solutions from single‐salt data
Authors: Nowlan Maarie‐France , Doan Thi Hoa , Sangster James
Published: March 2009

The viscosities of sonic mixed electrolyte solutions (NaCl + KCl, NaCl, + Nll4NO3, NaCl + CaCl2, NaCl + Ca(NO3)2, NaCl + MgSO4) have been measured to high concentration at 298 K. Existint: viscosity data for the single‐salt solutions have been fitted, as required, to Goldsack's two‐parameter equation. Mixed electrolyte data have been used to test the predictive accuracy of five simple methods of estimation. The usefulness and relative accuracies of the methods have been discussed briefly.
In‐situ volume fraction determination in multi‐component mixtures using pulsed nuclear magnetic resonance
Authors: Abouelwafa M. S. A. , Kendall E. J. M.
Published: March 2009

A simple method of determining in‐sitn volume fractions in multiphase or multi‐component systems using pulsed nuclear magnetic resonance is proposed and discussed from both the theoretical and experimental point of view. A 180° ‐ τ ‐90° pulse sequence was employed. Different mixtures were examined both analytically and experimentally and the results compared.
Drag reduction by fibers
Authors: Sharma R. S.
Published: March 2009

Drag reduction in turbulent pipe flow by means of boundary and centerline injection of long hair‐like asbestos fibers has been investigated. Pressure drop and mean velocity profiles were measured at various Reynolds numbers and injection rates in order to study some mechanistic aspects of drag reduction in water‐fiber and polymer‐fiber systems. Drag reduction in a water‐fiber system is attributed to a decrease in the momentum transfer in the turbulent‐core region, whereas synergism has been found to be a wall phenomenon.
Étude théorique et expérimentale de la formation d'une couche Limite par convection libre dans une eau à basse température
Authors: Vasseur P. , Robillard L.
Published: March 2009

A study, both analytical and experimental, has been made on the natural convection induced by an isothermal vertical plate immersed in a large volume of water at a temperature which was close to its freezing point. A particular attention has been paid to the effects resulting from the non‐linearity existing between the density of water and its temperature. when the latter was close to 4°C. The plate temperature (Tw) was in the range from 8.0°C to 27.2°C. while the water temperature (Ti) varied between 0°C and 22.2°C. The Prandtl numbers for the flow were in the range from 6.4 to 13.7. An excellent agreement between the theoretical solution and the experimental data has been observed.
Intraparticle effects in char combustion II. Steady state analysis
Authors: Srinivas B. , Amundson Neal R.
Published: March 2009

Based on the results of an earlier paper, a model is developed to include the homogeneous reaction in the external boundary layer. It is assumed, consistent with those results, that there is no homogeneous reaction within the particle. A feasibility region is constructed using limiting cases along the lines described there. Under some conditions, the model predicted up to five steady states for a given set of ambient conditions. For large particles, a flame develops in the boundary layer and the main product is CO2. Under such conditions, the reaction locus coincides with the double film model. While for small particles, no flame develops and the major product is CO. The solution is sensitive to the type of radiative interaction which obtains. The combustion rate increases with increase in particle temperature until a certain point, then decreases with further increase in temperature, and eventually turns back and increases again. Such behavior has been observed in some rate measurement experiments.
Vapor‐liquid equilibrium data for the methanol‐water‐sulphuric acid system at 101.3 kPa
Authors: Pinder K. L.
Published: March 2009

Atmospheric pressure vapor‐liquid equilibrium measurements were made on water‐methanol solutions with varying concentrations of sulfuric acid. Because of the reaction between methanol and sulfuric acid during the measurements, the maximum acid concentration useable was 20 weight percent. The mole fraction of methanol in the water‐methanol mixture was varied from 0.1 to 0.9.

The data were analysed as a “special binary” with the sulfuric acid as a non‐volatile component. An excellent fit to the data was given by the full equation by Jacques for binaries with a non‐volatile salt added.
Control of a distillation column using self‐tuning regulators
Authors: Dahlqvist S. A.
Published: March 2009

Self‐tuning regulators were applied to the multivariable control of a pilot distillation unit. Both the top and the bottom product compositions were simultaneously controlled. The multivariable interactions were compensated for by different strategies. It was shown that a proper choice of the control variables made it possible to use a regulator with a smaller number of parameters. The evaluation of the results shows that the self‐tuning regulator is a valuable tool in multivariable control of distillation columns.
An experimental study of the effects of surface characteristics and material thermal properties on dropwise condensation
Authors: Abdelmessih A. H. , Rotenberg Y. , Neumann A. W.
Published: March 2009

In this investigation, a study of the dropwise mode of condensation of water vapour at near atmospheric pressure was undertaken. Three vertically oriented condenser surfaces of different materials, copper, brass and stainless steel, were carefully prepared and heat transfer data were obtained over a long period of time as the surfaces continued to deteriorate.

The condensation heat transfer coefficient was found to decrease with increasing surface deterioration. It is also evident that further work is needed before a general model can be developed to predict heat transfer in dropwise condensation. However the effect of surface characteristics and material thermal properties on strong dropwise condensation at small vapour to surface temperature differences is evident from the present results.
Measuring and modelling forest evapotranspiration
Authors: Spittlehouse D. L. , Black T. A.
Published: March 2009

Micrometeorological methods of measuring and modelling forest evapotranspiration are reviewed and evaluated. Measurement methods include eddy correlation, aerodynamic, Bowen ratio/energy balance and stomatal diffusion resistance techniques. Modelling approaches discussed include a model relating evapotranspiration rate to the root zone water content and the net radiation flux, the Penman equation, and vapour diffusion models requiring stomatal resistance characteristics of the stand. Measured and modelled estimates of evapotranspiration from a Douglas‐fir stand are compared.
Heat flow between large terrestrial animals and the cold environment
Authors: Christopherson R. J. , Young B. A.
Published: March 2009

Estimates of the rates of heat loss and resistances to heat loss from large animals in cold environments have been made from steady state measurements of metabolic rate using indirect respiration calorimetry and measurements of deep body and surface and air temperatures. These estimates can be used to predict an animal's lower critical temperature (ambient temperature below which an animal has to increase its rate of heat production to prevent hypothermia) and the increased heat flow during cold stress. Data from experiments at the University of Alberta have been summarized together with data from the research literature. Resistances to body heat loss expressed as insulation values are influenced by animal size, amount of subcutaneous fat, hair coat thickness, air movement and moisture conditions. Increasing the level of food intake and cold acclimation increase the resting metabolic rate and lower the lower critical temperature of animals.
Development and testing of a method of estimating sensible heat flux from natural surfaces using remotely sensed surface temperatures
Authors: Leckie D. G. , Black T. A. , Murtha P. A.
Published: March 2009

Remote sensing techniques for the determination of the sensible heat flux component of the energy balance of natural surfaces have applications to several fields of study. Research into the use of a night‐time cooling model for remote sensing thermal inertia mapping which has applications to soil moisture measurement and geologic interpretation prompted the following study. The theoretical framework is presented for a method of determining sensible heat flux in a stable boundary layer from input parameters of radiometrically determined surface temperature, surface roughness, and the air temperature and wind speed at one height above the surface. Corrections for stability and the surface sublayer are included. The method is tested over a vegetated and a non‐vegetated surface using ground based data. Given accurate input parameters, the method gives excellent results for the non‐vegetated surface, but unreliable results for the vegetated surface.
Transient heat transfer and fluid mechanics of a recirculating pressurized water loop during blowdown and cold water injection
Authors: Barclay F. W. , Nieman R. E. , Hasinoff M. P.
Published: March 2009

Mathematical models, in the form of computer codes, are used to evaluate the performance of process and safety systems of CANDU nuclear reactors during normal operation and postulated accident conditions. To validate the models, predictions are made of the transient heat transfer and fluid mechanics processes in pressurized water loops following simulated pipe ruptures. These loops have the essential geometric and physical characteristics of a CANDU reactor primary heat transport system. Comparisons with data from loops of different scales over the conditions of interest (blowdown and cold water injection) are used to illustrate that the models predict the trends in the experiments adequately when the assumptions inherent in the model (e. g. equal steam and water velocities) are valid. To improve accuracy in cases where these assumptions do not apply, a more sophisticated representation of two‐phase flow is required.
Wall shear stress and mass transfer in vertical two‐component flow
Authors: Surgenor B. , Banerjee S.
Published: March 2009

Mass transfer rates in vertical gas‐liquid flow were measured by an electrochemical technique. The flow regimes studied were slug, churn and annular. Average mass transfer coefficients in gas‐liquid flow could be correlated by expressions similar to those for single phase flow. Fluctuations in local mass transfer coefficient could be used to indicate flow regimes. Average wall shear stress determined from the average mass transfer coefficients agreed with values calculated from measurements of pressure drop, void fraction and flow rate, provided flow reversals did not occur. The results indicate that the electrochemical technique could be used to measure wall shear stress in accelerating gas‐liquid flows, such as critical flow.
Heat transfer from cylinders in unsteady flow
Authors: Base T. E. , Patel J. M. , Valaitis G. C.
Published: March 2009

The paper is concerned with the experimental determination of the forced convective heat transfer from heated cylinders when the approaching flow has low frequency oscillations in the magnitude of the free stream velocity. Initial tests showed that at very low reduced frequency values, based on the cylinder diameter and the mean flow speed, up to values of .01, a reduction in the Nusselt Number value of up to 12% below the Nusselt Number for uniform approaching turbulent flow was recorded. For reduced frequency values above .03, an increase in the Nusselt Number to the original value when the flow was steady was measured.
Hydrotransport of solids in horizontal pipes: Effects of solids concentration and particle size on the deposit velocity
Authors: Parzonka W. , Kenchington J. M. , Charles M. E.
Published: March 2009

Correlations previously proposed in the literature for the deposit velocity in the flow of settling slurries in horizontal tubes generally predict increasing values with increasing solids concentration. However, the present comprehensive investigation which has drawn on data from a broad geographical base, confirms that the deposit velocity shows a maximum with respect to concentration and decreases above about 15% by volume solids. It is also shown that the presence of fine particles (<75 μm) is particularly significant in determining the degree of the reduction in the deposit velocity for the higher concentrations. This reduction would appear to be due primarily to a significant increase in the drag coefficient for particles settling in a fine particle suspension, i.e. heavy medium. The data are summarized in graphs for a variety of materials including sand, gravel, iron ore and coal.
Bubble pumping in cocurrent gas‐liquid flow and its effect upon conversion in continuous fermentation
Authors: Wick Emil
Published: March 2009

Bubble pumping was demonstrated in cocurrent, gas‐liquid flow through experimental vessels which had been used to carry out continuous alcohol fermentation. The pumping rates, measured with a video‐tape technique during cocurrent upward flow, were used to compare these vessels as gas‐lift pumps to some actual air lift pumps. The effect of bubble pumping upon the conversion achieved in these vessels is shown and the significance of this for vessel design is discussed.
Capsule hoist system for vertical transport of coal and other mineral solids
Authors: Hwang L. Y. , Wood D. J. , Kao D. T.
Published: March 2009

A capsule hoist system for the vertical transport of solids in pipelines is studied. For this system a cylindrical capsule loaded with cargo is inserted into the lower end of a vertical liquid filled tube. The capsule which is of lower average density than the liquid is lifted due to natural buoyant forces. A theoretical analysis of capsule speed and system transport efficiency is carried out.

The predicted results are in good agreement with a substantial number of experimental results. Of particular interest was the effect of the ratios of capsule diameter to tube diameter, capsule diameter to capsule length and average capsule density to liquid density.

The principal goal of the study is to determine design factors which will maximize the rate of hoisting cargo for a particular system. It was concluded that the best ratios for capsule diameter to tube diameter and capsule density to liquid density are both approximately 2/3. It was further concluded that capsule length and the shape of the capsule nose has little influence on the efficiency of this transport system.