bluuebunny/crossref_metadata_2025 huggingface dataset:
Chlorine exchange resins, effects of resin formulation on exchange properties
Authors: Dewar E. J. , Wayman M.
Published: March 2009

Chlorine exchange resins prepared from urea, melamine and formaldehyde in various ratios and under various conditions were found to vary widely in physical structure, diffusion coefficients and capacity to absorb chlorine. Resins prepared by relatively intensive heating of the methylol syrup, or by condensation at relatively high pH, about 5, or by condensation at low temperature appeared to undergo some phase separation resulting in an opaque white resin with a macroreticular structure. Such resins had good physical stability. The opaque, porous, macroreticular resins generally had higher effective diffusion coefficients, but lower chlorine absorption capacity, than the relatively uniform translucent resins.

An increase in the water content of the resin from 50 to 65% resulted in an increase in the effective diffusion coefficient (D̄) by a factor of 3, and a small increase in chlorine capacity.

D̄ was a maximum when the pH of the chlorinating solution was about 3, suggesting that HOCl is the diffusing species.

The production of these resins in bead form by suspension polymerization is described.
A molecular approach to the calculation of gas adsorption isotherms on molecular sieves: Noble gases on type 4A and 5A zeolites
Authors: Lee A. K. K. , Basmadjian D.
Published: March 2009

A general equation for gas adsorption isotherms in microporous adsorbents is derived on the basis of the molecular chemical potentials of the gas and adsorbed phases and the theory of volume filling of the adsorption space by adsorbate molecules. Both adsorbate‐absorbate and adsorbate‐adsorbent interactions are considered in computing the molecular free energy of adsorption.

The equation is applied to the calculation of isotherms of noble gases on molecular sieves type 4A and 5A in the range 77.4°K to 333°K, 0.001 mm Hg to 40 atmospheres. Comparison of the calculated isotherms and experimental data shows that the adsorption equation can be used over a wide range, but requires interpolation over a short intermediate region of adsorbate concentrations. An important feature of this equation is that it reduces to Henry's law at low adsorption concentrations.
Evaporator control system design
Authors: Ritter R. A. , Andre H.
Published: March 2009

The design of a suitable conventional control configuration for a double effect evaporator was readily achieved through an examination of a linearized form of the dynamic model for the system. All possible control schemes were identified, then evaluated with reference to the model. A rather extensive experimental program established that the selected control scheme was most satisfactory, both from the point of view of stability and quality of response.
Optimum utilization and replacement policies for decaying catalysts
Authors: Miertschin G. N. , Jackson R.
Published: March 2009

The optimum catalyst replacement policy, length of operating cycle, and temperature program are determined for simple types of reactors operated with constant exit conversion. For certain circumstances it is shown that the spent catalyst should not be replaced completely by new catalyst at the beginning of a cycle.
Residence time distribution functions for stirred tanks in series
Authors: Stokes R. L. , Nauman E. B.
Published: March 2009

Many physical systems are modeled as a number, N, of stirred tank reactors in series. In fitting experimental data, it is necessary to consider the case where N is not an integer. Two noninteger extensions to the tanks‐in‐series model are discussed. Methods for data reduction are presented and compared for a set of experimental measurements on a single stirred tank reactor.
Improved waterflooding through mobility control
Authors: Mungan N.
Published: March 2009

Increasing the viscosity of injected water for more efficient oil recovery has been of interest to the petroleum industry since 1900. In recent years, certain high molecular weight water soluble organic polymers have been developed which, in small concentrations, can increase the viscosity of water substantially and, under certain conditions, recover additional oil economically.

The rheological properties, adsorption, transport characteristics, and oil recovery efficiency of several polymer solutions are presented. The viscosity of the polymer solutions depends largely on the flow rate, the type of polymer, and the solvent. Oil recovery depends primarily on the permeability distribution of the porous model. Adsorption varied from 30 to 225 μg/g. Because the process utilizes a polymer solution slug of small volume, the stability of the slug was considered. Following a polymer slug with water led to viscous instabilities and slug breakdown. If the polymer concentration in the slug was reduced to zero asymptotically before injecting water, the viscous instabilities were eliminated.
The influence of water on the rhythmic process of precipitation of ammonium chloride formed by the counterdiffusion of ammonia and hydrogen chloride
Authors: Davies G. A. , Ponter A. B. , Singh S.
Published: March 2009

Results are reported for the formation of ammonium chloride by counter diffusion of ammonia and hydrogen chloride over the temperature range 25 ‐ 40°C. Two modes of precipitation were observed, continuous and periodic precipitation (formation of Liesegang rings). The results establish that the presence of moisture is the important factor controlling the mechanism of precipitation, a minimum moisture content of approximately 100 ppm being required for formation of Liesegang rings. Under these conditions the concentration product was found to be very much greater than the thermodynamic minimum value confirming that nucleation of the solid product regulates the process.
Effect of surface heterogeneity on surface diffusion in microporous solids
Authors: Horiguchi Y. , Hudgins R. R. , Silveston P. L.
Published: March 2009

An experimental investigation of the effect of surface energetic heterogeneity on surface diffusion using Vycor and Graphon and as gases ethane, propylene, nitrogen, and helium confirms published reports that surface diffusion proceeds more rapidly on the energetically homogeneous Graphon surfaces. Activation energies for diffusion are found to be about the same for Vycor and Graphon; thus, it is postulated that a major factor in the difference is surface roughness. A comparison of surface diffusion models shows that Fick's Law correlated results about as well as a hydrodynamic model. Both models fail to allow adequately for surface coverage. A comprehensive form of Fick's Law for surface diffusion is proposed.
Controlled cycling extraction: Part i. performance of an experimental column
Authors: Darsi C. R. , Feick J. E.
Published: March 2009

A 4‐in. diameter controlled cycling extractor using dual flow sieve trays was built and operated successfully on the test system water‐acetic acid‐methyl isobutyl ketone at realistic concentration levels and solute transfer in both directions. The most important parameters of industrial importance, the capacity and efficiency of the column, were studied in detail. Comparisons made with conventional operation show that the efficiency is at least 100% better, and capacity increases of 50% over the flooding point (in conventional operation) or higher are easily obtained. The practical and economic aspects of column operation are discussed. A transient model for a controlled cycling (CC) extractor using the concept of mixing stages was developed. The model predicts the increases in efficiency observed experimentally, and also gives an insight into the control aspects of the CC extractor.
Prediction of the viscosities of liquid mixtures by a group solution model
Authors: Ratcliff G. A. , Khan M. A.
Published: March 2009

Group solution models of liquid mixtures have been used previously to predict thermodynamic properties of non‐ideal systems. A model of this type has been developed which enables the viscosities of liquid mixtures to be predicted. The concept of an “ideal viscosity” is introduced, and allowance made for the interaction between the groups present and for the structural contributions of differing molecules. Predictions require a knowledge of only the viscosities of the pure components of a mixture. It has been tested for mixtures of alkanes, alcohols and water at 25°C, and gives good agreement with experiment. Experimental viscosities for ethanol/n‐hexane, for n‐propanol/water, and for four multi‐component mixtures at 25°C are presented.
Heat transfer in the cooling of thermoplastic melts under pressure
Authors: Kenig S. , Kamal M. R.
Published: March 2009

The dimensionless equations describing the cooling with solidification of polymer melts under pressure are solved numerically for partially crystalline and glassy polymers. The proposed finite‐difference solution assumes constant, but different, average properties for each of the amorphous and crystalline phases. Natural convection is ignored (Grashof Number <10−8), and internal flow as a result of pressure gradients and the effect of pressure anisotropy on temperature profiles have been neglected. Numerical predictions of temperature profiles, pressure, and the position of the freezing front in a long, cylindrical mold are in good agreement with experimental data.
Sound emission from boiling on a submerged wire
Authors: Haigh C. P. , Ponter A. B.
Published: March 2009

The sound accompanying nucleate and film boiling on a platinum wire immersed in a water pool at atmosphere pressure is related to the rate of heat transfer from the wire surface. In particular the total sound intensity is shown to be a function of the heat transfer resulting from bubble evolution. Analysis of the acoustic spectra for saturated and sub‐cooled boiling shows how the level of selected components varies with changes in the heat flux and liquid temperature.

The possibility of using an acoustic detection device to detect boiling caused by channel blockage in a liquid cooled system is discussed.
Prediction of excess free energies by a group solution model with application to alkane/ketone mixtures
Authors: Maripuri V. C. , Ratcliff G. A.
Published: March 2009

The group solution model of Ratcliff and Chao for the excess free energies of liquid mixtures has been tested and found satisfactory for eight mixtures of alkanes and ketones. The model was tested by comparing experimental and predicted vapor‐liquid equilibrium data.

Group contribution functions were generated from experimental data on acetone/n‐heptane mixtures at 65°C, and are presented. These functions allow the prediction of excess free energies of binary or multicomponent mixtures containing alkanes and ketones at 65°C. No experimental data is required. Predictions at temperatures close to 65°C, using the same functions, should be satisfactory.
Optimization of reactors with catalyst decay iii‐tubular reactor with several beds of uniform temperature
Authors: Crowe C. M. , Lee S. I.
Published: March 2009

The temperature of a series of beds are chosen with time so as to maximize the overall production of an irreversible reaction, over a fixed total time. Each bed has uniform temperature and activity at any instant and the catalyst activity decays at a rate which is independent of conversion.

It is shown that the temperature of each bed should finally be at the upper limit. Further, if no bed temperature is constrained, for constant inlet composition the conversion out of every bed should be held constant. Under certain conditions, it is best to shut some beds down temporarily, to save their activities for later. Numerical examples are given.
Properties of the n‐methyl‐2‐pyrrolidinone‐water system
Authors: MacDonald Digby D. , Dunay D. , Hanlon G. , Hyne J. B.
Published: March 2009

Densities, excess volumes and heats of mixing, heat capacities, refractive indices and viscosities of various N‐methyl‐2‐pyrrolidinone (NMP)‐water mixtures are reported. The excess volumes and heat of mixing are negative and show their greatest deviations from ideality at 0.3 ‐ 04 mole fraction NMP. The viscosity of the system passes through a maximum in the same region of solvent composition. These data indicate strong interaction between NMP and water and suggest the existence of transient polymeric species of the type — (NMP · 2H2O)n̄.
Surface rheological properties of polymer‐surface active agent solutions
Authors: Vocel J. , Ryan J. T.
Published: March 2009

The rheological properties of the surface of two anionic and a nonionic water soluble polymer solutions in the presence of alkylarylsulfonate and lauryl alcohol were studied. Changes in the properties of the surface after degradation with ozone were also investigated. Measurements were made with a surface viscometer attached to a Weissenberg Rheogoniometer. A model consisting of one Maxwell element is proposed to interpret the experimental data.
Heat transfer from a turbulent hot air jet impinging normally on a flat plate
Authors: Vlachopoulos John , Tomich John F.
Published: March 2009

The heat flux distribution on a flat plate resulting from a normally impinging free jet of hot air was measured for a variety of experimental conditions. A method has been developed for calculating local heat flux in terms of nozzle exit parameters, nozzle to plate spacing and surface temperature distribution. The applicability of this method has been thoroughly checked by comparing computed and measured heat flux distributions for nozzle to plate spacings of 3.41 to 31.05 nozzle diameters; nozzle exit temperatures of up to 1149°F; and nozzle exit Mach numbers of up to 0.837.
Approximation methods for optimal control synthesis
Authors: Hicks G. A. , Ray W. H.
Published: March 2009

A number of approximate methods for optimal control synthesis are reviewed and tested on a highly non‐linear continuous‐stirred‐tank‐reactor example. It was found that parameterizing a feed‐back controller and searching for the optimal coefficients was computationally as fast as the standard conjugate gradient approach. Ancilliary advantages of this approach make it an attractive means of optimal control synthesis.
Absorption of carbon dioxide in ethylenediamine solutions ii. pilot plant study of absorption and regeneration
Authors: Trass Olev , Weiland R. H.
Published: March 2009

Carbon dioxide removal by aqueous ethylenediamine has been studied in 4‐inch diameter absorption and stripping columns packed with 1/2‐inch Intalox saddles

Mass transfer coefficients for absorption were appreciably gas phase controlled and three to four times greater than those for caustic soda. Film theory predictions reproduced the absorption data to within 20% or better

Equilibrium data were obtained by using the stripping column reboiler as an equilibrium stage. The enthalpy and rate of carbamate decomposition were inferred from these results, and transfer unit heights were determined for stripping

The economics of this process are unfavourable because of the high steam demand and suggest that regeneration equilibria alone can be used for the rough evaluation of new chemical absorbents
Kinetic analysis utilizing a recirculating flow reactor system
Authors: Osborne F. T. , Martin D. C. , Stannett V. T. , Stahel E. P.
Published: March 2009

A system which recirculates reactants from a stirred vessel through a remote reactor is described. Highly reproducible kinetic measurements are achieved for liquid phase reactions in general and those requiring isolation in particular. Typical reactions which require isolation involve high pressure, intense radiation, explosive mixtures, etc. The conversion history within the vessel is related to reaction rate through a mathematical model which facilitates interpretation of kinetic data. The stirred vessel is modeled as a perfectly uniform reservoir coupled to the arbitrary reaction element by two transfer lines modeled as time delays. The analysis includes the effects of a parabolic velocity profile attendant to the use of low circulation rates or high viscosities. Analytical solutions are obtained for limiting cases and the model system simulated on an analog computer. The results are compared to experimental data on a radiation induced vinyl polymerization
Calcium carbonate precipitation in a continuous stirred tank reactor
Authors: Maruscak A. , Baker C. G. J. , Bergougnou M. A.
Published: March 2009

The precipitation of calcium carbonate, brought about by mixing aqueous solutions of calcium nitrate and sodium carbonate in a continuous reactor, has been studied. The pH (8.5‐10.0), reagent concentration (0.25‐1.7 N), temperature (15‐60°C), residence time (1‐3 min), and mixing speed (100‐500 rpm) were chosen so that the effects of agglomeration could be examined

The presence of agglomerates was confirmed by microscopy. Precipitate size distributions were log normal, and the geometric mean diameters, ranging from 5 to 13 p.m, were extremely sensitive to pH. Large precipitates were obtained under conditions favouring a high agglomeration rate; namely high temperatures, concentrations, and mixing speeds. The effect of residence time was minimal. The geometric standard deviation increased with the mean size of the precipitate. The solids recovery decreased with increasing temperature, but was not significantly affected by the other parameters
Large scale process optimization techniques applied to chemical and petroleum processes
Authors: Jung B. S. , Mirosh W. , Ray W. H.
Published: March 2009

Some approaches for finding the solution to large scale process optimization problems are discussed. Several popular nonlinear programming algorithms are tested and conclusions reached about their suitability for chemical process optimization. Decomposition procedures are also discussed and numerical studies made to examine the relative merits of decomposition vs. “black box” optimization strategies. Test problems include an oil refinery scheduling problem and a chemical process optimization problem
Compensation for unknown input disturbances in multiple‐input identification and optimal control
Authors: Corlis R. G. , Luus Rein
Published: March 2009

The identification and optimal control of multiple‐input, single‐output chemical processes subjected to unknown disturbances is considered. The parameters of the model are estimated by an augmented least squares procedure which takes the noise into consideration by an additional noise shaping filter. The multiple‐input identification problem is then reduced to a set of single‐input problems by a stepwise least squares procedure operating on residuals. A two‐input shell and tube heat exchanger demonstrates the practical nature of the procedure. Based on the identified model, an optimal feed forward‐feedback controller can predict the effects of the input disturbances to compensate for these effects
A practical method for discriminating among mechanistic models
Authors: Hsiang Thomas , Reilly Park M.
Published: March 2009

A method is presented for designing and analysing experiments for choosing the best mechanistic model among a set of more than one to describe a real‐world relationship. The method is a personalistic Bayesian one which does not depend on linearization of the models or on any specific form of the error distributions. Examples illustrating different types of applications of the method are given
On minimum power requirements for emulsification of two‐phase, liquid systems
Authors: Esch D. D. , D'ANGELO P. J. , Pike R. W.
Published: March 2009

Power requirements were measured for several, two‐phase, liquid systems with viscosities ranging from 0.391 to 215 centipoise in a baffled, cylindrical vessel conforming to a standard tank configuration. A correlation was developed for the minimum power needed in order to maintain a uniform emulsion. For the systems studied it was found that the product of minimum impeller speed and the weighted average density was only a function of the respective continuous phase properties. Measurements, made over a range of impeller speeds from the minimum required to maintain an emulsion up to the point where gas entrainment occurred, were accurately described by single phase power curve. For more than 250 points with Reynolds numbers ranging from 500 to greater than 100,000, the average absolute error in the experimentally measured power number for two phase systems was found to be 4.0% based on the corresponding single phase power number curve
New mixing rules for the BWR parameters to predict mixture properties
Authors: Bishnoi P. R. , Robinson D. B.
Published: March 2009

New mixing rules which are general and easy to use have been developed to predict the properties of mixtures from the BWR equation. The rules contain a binary interaction parameter, readily obtainable from the experimental values of the second virial cross‐coefficients. The mixing rules were used to predict the densities of binary mixtures of carbon dioxide with methane, ethane and propane at elevated pressures. For any of the three mixtures, the standard error of the predictions was approximately equal to or less than the sum of the standard errors of fit for the pure components. The BWR parameters for the pure components, required in the above predictions, were determined by minimizing the sum of relative error squares in specific volume.
Secondary sewage treatment in pipeline contactors
Authors: Russell T. W. F.
Published: March 2009

The preliminary design steps for a secondary sewage treatment process are discussed in a case study format. A tubular contactor with an oxygenator and reactor section is proposed as an alternate design to the conventional open tank process.
Fluid‐fluid interactions and hydrodynamics in agitated dispersions: A simulation model
Authors: Zeitlin M. A. , Tavlarides L. L.
Published: March 2009

A model which accounts for complex fluid‐fluid interactions and hydrodynamic effects in a fully baffled turbulently agitated dispersed phase system for batch, semi‐batch, or continuous operation is developed. Both micromixing and macromixing effects on particle size distributions are taken into account. Coalescence and breakage functions are developed and examples are given of the normalized number and/or volume size distributions for various vessel regions. Calculated distributions are compared with experimental data to estimate values of coalescence and breakage parameters. Effects of coalescence, breakage, and system parameters on transient and steady state distributions are determined.
Pressure drop in a mobile‐bed contactor
Authors: Tichy J. , Wong A. , Douglas W. J. M.
Published: March 2009

The overall pressure drop and the vertical static pressure profile in a 0.14‐m. diameter mobile‐bed contactor have been investigated for two packing sizes and three packing heights. The gas and liquid flow rates were the two other variables studied. Foam polystyrene spheres were used as packings.

The relationship between the static pressure and vertical position of the bed was found to be linear. A correlation of the drag parameter with Gg, Gt and Lp is presented. States of fully‐mobile bed operation are discussed.
A mathematical simulation of radiant heat transfer in a cylindrical furnace
Authors: Osuwan S. , Steward F. R.
Published: March 2009

The radiative heat transfer in a cylindrical furnace was investigated both experimentally and theoretically.

The flow pattern within the combustion chamber was measured and found to differ from that of an identical cold model for which extensive theoretical and experimental work had been previously carried out.

The Monte Carlo Method was used to solve for the radiative transfer part of the non‐linear integro‐differential equations describing the combustion and heat transfer in a cylindrical furnace.

The radiative heat flux distribution obtained from the simulation agreed well with data obtained from a cylindrical test furnace.
Heat transfer in tubes and ducts with wall mass transfer
Authors: Raithby G. D.
Published: March 2009

This study is concerned with the developing temperature field for flow in circular tubes and parallel plate channels with mass transfer through the wall. Some unique features of the developing temperature field are outlined for both constant temperature and constant heat flux boundary conditions. Solutions to the heat transfer problem are extended to include arbitrary prescribed temperature or heat flux boundary conditions. A practical problem is solved in two ways, utilizing respectively these solutions, and a comparison of the results is made.
A general asymptotic analytical solution for non‐catalytic gas‐solid reactions
Authors: Williams R. J. J. , Calvelo A. , Cunningham R. E.
Published: March 2009

The reaction between a porous solid pellet and a gas is analyzed in the asymptotic region of the effectiveness factor. The solid consumption is divided in two stages. The influences of effective diffusivity and surface area profiles are taken into account for both stages through a correction modulus of the effectiveness factor. The conversion — time relationship can be calculated for a selected model of porous structure and any reaction order for the gaseous reactant. The results are extended to non‐equimolar counterdiffusion and a non‐isothermal situation with external heat and mass transfer resistances.
Second virial coefficients of polar gases — a correlation with stockmayer potential function
Authors: Polak Jiri , Lu Benjamin C. Y.
Published: March 2009

The parameters of the Stockmayer potential function were calculated by a least‐squares analysis of the second virial coefficient data for 66 polar substances. By using these parameters, the second virial coefficient of these tabulated materials can be calculated with a mean standard deviation of 20.2 cm3 mole−1 or 3.2%. The possibility of extrapolating second virial coefficients from high to low temperatures is also demonstrated.
The hydrodynamics or gas‐liquid contacting in towers with fluidised packings
Authors: O'neill B. K. , Nicklin D. J. , Morgan N. J. , Leung L. S.
Published: March 2009

A model is developed of gas liquid contactors in which packing pieces are maintained in the fluidized state. The model proposes that the column can exist in either of two modes, namely fluidisation without flooding and fluidisation due to incipient flooding. The mode of operation established depends primarily on the packing density and to a lesser extent on the packing size, liquid flow and liquid properties. Equations predicting the transition from one mode to the next are developed. The inherent advantages of operating in the “incipient flooding” mode are stressed. It is argued that the pressure build up associated with flooding will be sufficient to support the weight of packing pieces and the liquid in the column. At this stage, rather than reject counter current flow (true flooding) the bed expands to maintain a state of incipient flooding. In this way counter current flow can be maintained in a situation well above the normal flooding point. This explains the high performance of such units.
The flow of thin films inside rotating cylindrical tubes
Authors: Barnea E. , Kovalivker E. , Mizrahi J. , Yacoub N.
Published: March 2009

A mathematical model was derived for the calculation of the film thickness, total holdup and overall residence time of a thin liquid film flowing inside a rotating cylindrical tube, as a function of the liquid throughput and physical properties and of the tube diameter, length, rotational speed and angle of inclination.

The experimental data with short tubes showed good agreement with the model for average film thickness above a certain critical value (which may indicate a change in the flow regime).
Hold‐up and axial mixing characteristics of two and three phase fluidized beds
Authors: Kim S. D. , Baker C. G. J. , Bergougnou M. A.
Published: March 2009

The hydrodynamics of two (water‐air, water‐solids) and three (water‐air‐solids) phase fluidized beds have been studied in a large two‐dimensional column. Two solids were used, namely 6 mm glass beads and 2.6 mm irregular gravel.

The individual phase holds‐ups, bed expansion, and axial mixing characteristics were measured. The data were correlated empirically by equations involving liquid and gas phase Reynolds and Froude numbers, and the ratios of the particle and fluid densities. Bubble sizes and rising velocities were determined photographically and found to be of great importance in determining the hydrodynamics of the different beds.
Influence de léagitation mécanique sur les transferts thermiques en fluidisation homogène
Authors: Varela B. , Couderc J. P. , Angelino H.
Published: March 2009

It is possible, through the use of an agitator with a particular shape which renews in a rapid sequence the matter contacting the column walls, to increase significantly the intensity of the thermal transfer between a liquid fluidized layer and the walls. It is shown experimentally that the rotative speed of the agitator has an important effect on the transfer. The whole results are qualitatively interpreted within the framework of a transiant‐state mechanism.
Viscosity of nitrogen gas at low temperatures up to high pressures: A new appraisal
Authors: Latto B. , Saunders M. W.
Published: March 2009

The absolute viscosity of nitrogen gas was determined experimentally for the pressure and temperature range 1 to 150 atmospheres and 90°K to 400°K respectively. The maximum error in the data presented is believed to be better than ±1.5%, and ±1% for the high and low pressure data respectively.

Two general correlating equations, one for atmospheric pressure and the other for all the available high pressure data, (i.e. densities up to 0.4 g/cc or 1.5 ρ (critical)) are presented, together with a table of recommended smoothed data, which are felt to be accurate to ±1.5% or better. Values for the low velocity collision diameter σ and maximum energy attraction functions are also presented for the low pressure data.
Application of wilsonés equation to determination of vapor‐liquid equilibrium data and heats of mixing for non‐ideal solutions
Authors: Tai Trinh Ba , Ramalho Rubens S. , Kaliaguine S.
Published: March 2009

A calculation technique, starting from total pressure data of binary systems and utilizing Wilsonés equation was developed, leading to isothermal vapor liquid equilibrium data for binary and ternary systems. Heats of mixing for ternary systems were also calculated from binary data.
Parameter estimation using linear programming and quasilinearization
Authors: Nieman R. E. , Fisher D. G.
Published: March 2009

A generalized algorithm for the estimation of parameters in a process model from experimental data is presented in this paper. The algorithm, which combines linear programming with quasilinearization, is formulated and its advantages and limitations are discussed. Examples are included to illustrate application of the algorithm to real engineering problems, one of which was encountered in industry and another of which was encountered in a control study. The examples demonstrate the incorporation of constraints, convergence promotion and reliability estimates into the identification.
Vertical pneumatic conveying: A theoretical study of uniform and annular particle flow models
Authors: Capes C. E. , Nakamura K.
Published: March 2009

Two models for vertical pneumatic conveying, a uniform flow model at high gas velocities and an annular flow model near the particle terminal velocity, have been examined theoretically. The uniform flow model leads to the following relationship between gas and particle velocity and line porosity:

No simple analytical solution was found for the annular flow model but a numerical solution was possible.

Both models indicate that slip velocity may exceed the particle terminal velocity under certain conditions. The theoretical predictions agree reasonably well with experimental observations.
Flow behavior of power‐law fluids in the entrance region of annuli
Authors: Tiu Carlos , Bhattacharyya Satinath
Published: March 2009

Momentum‐integral and momentum‐energy‐integral methods are used to study the laminar entrance behaviour of power‐law fluids in annuli. The momentum‐energy method, which yields a longer entry length, appears to provide a better overall description of the entry flow behaviour. The method compares favourably with the existing Newtonian solutions for annular flow and with the non‐Newtonian flow in pipes and parallel plates in the limiting cases. The linearisation technique is also extended to power law fluids utilising the geometric parameter method. The loss coefficients predicted by the linearisation technique agree well with those obtained by the integral methods.
Wall heat transfer to chemical reactors
Authors: Chao Raul E. , Caban R. A. , Irizarry M. M.
Published: March 2009

The effects of chemical reactions on wall heat transfer coefficients in packed bed reactors operating at equilibrium or near equilibrium conditions are explored by means of one‐dimensional and two‐dimensional models. Both approaches suggest using Damköhler number or ratios of reacting to frozen heat capacity as parameters in heat transfer correlations. Available data for the methane‐steam reforming reactors were used to establish a suitable correlation for use in thermal design of reacting beds of solids, i. e. NNu = 0.195 NRe0.8 exp. (0.21 σ)

This correlation can be applied with reasonable accuracy for beds which are 3 to 5‐in. in diameter and bed to particle diameter ratios from 5 to 10. A review of available correlations for wall coefficients obtained under non‐reacting packed bed conditions is also presented.
Synthesis of an optimal large‐scale interconnected system by structural parameter method coupled with multilevel technique
Authors: Osakada K. , Fan L. T.
Published: March 2009

The combined use of the structural parameter method and the multi‐level technique is proposed for optimal process system synthesis. An iterative procedure for implementing the technique is presented. The use of this technique is illustrated by synthesis of a reactor‐separator system.
Some observations on uniqueness and multiplicity of steady states in non‐adiabatic chemically reacting systems
Authors: Varma Arvind , Amundson Neal R.
Published: March 2009

An investigation of uniqueness and multiplicity of the steady states in two non‐adiabatic chemically reacting systems, the stirred tank and the tubular reactors, is presented. Exact uniqueness and multiplicity criteria are presented, and some conclusions derived therefrom, for the stirred tank reactor. For the tubular reactor, some numerical results are reported and multiplicities of the type 1‐3‐1, 1‐3‐1‐3‐1 and 1‐3‐5‐3‐1 noted. Criteria obtained earlier and those obtained from a lumping approximation of the distributed system are evaluated. In addition, two asymptotic solutions are obtained for the non‐adiabatic tubular reactor.
A general method of predicting the water activity of ternary aqueous solutions from binary data
Authors: Chen H. , Sangster J. , Teng T. T. , Lenzi F.
Published: March 2009

An isopiestic method has been developed to predict aw for ternary solutions from binary aw data. Another method, previously outlined by Robinson and Bower, has been extended to include non‐electrolytes. Both methods have been used to predict aw's for 51 representative systems. The results show that the isopiestic method is as good as, or better than Robinson and Bower's in predicting aw for ternary aqueous electrolyte/ electrolyte, electrolyte/non‐electrolyte and non‐electrolyte/non‐dectrolyte systems.

Calculated aw values are in good agreement (<0.5%> error on the average) with experiment.

The methods are applicable to relatively concentrated solutions up to 12 m.
Flow patterns in viscoelastic liquids upstream of orifices
Authors: Oliver D. R. , Bragg R.
Published: March 2009

The flow patterns obtained when aqueous polyacrylamide solutions flow into orifices are photographed. The polymer concentrations are 0.01, 0.03 and 0.10 per cent, the orifice diameters 1.27, 0.95, 0.50, 0.20 and 0.10 cm and the flow velocities 7‐700 cm/sec.

Various flow patterns are identified, including the well‐defined conical form. The semi‐angle of the cone decreases with decreasing orifice size and also depends on flow velocity, particularly when the larger orifices are being used. Cone angle also depends on the concentration of the solution. The flow pattern sometimes changes abruptly when flow velocity is increased; flow instability is often present.

Finally, it is suggested that the flow pattern is established as a result of interplay between extensional forces present in the liquid at the orifice and viscous and kinetic effects in the upstream fluid.
Heat transfer from a vibrating vertical array of horizontal cylinders
Authors: Hsieh R. , Marsters G. F.
Published: March 2009

Results are presented for experiments performed on a vibrating array of five identical heated cylinders. The cylinders are arranged with their axes horizontal and in the same vertical plane. They are held by a U‐shaped yoke. The spacing between cylinders was set at two diameters for most of the work. The array yoke is clamped to a resonant beam which is driven by a magnetic vibrator. The range of vibration intensities from zero to 0.61 has been studied. The vibrating array showed an increase in heat transfer rate of up to 54% for the conditions covered in this report. The trend of the data indicates greater increases at higher vibration intensities.
The effect of local gas velocity and temperature on local heat transfer to a sphere in a high‐temperature jet
Authors: Katta S. , Gauvin W. H.
Published: March 2009

Correlations for overall or local heat transfer to spheres based on flow conditions prevailing just ahead of the sphere or in its absence constitute an oversimplification, particularly in the presence of the steep temperature and velocity gradients existing in a plasma flame. This study presents correlations based on local values of heat flux and on local values of the free‐stream temperature and velocity of an argon plasma jet, as well as data obtained in helium. A single correlation for the argon and helium data was obtained with the use of a thermal conductivity ratio correction. The characteristics of the argon plasma jet were interpreted according to classical jet mixing theory.
Influence de la pulsation sur les transferts de matière entre une sphère et un liquide
Authors: Gibert H. , Angelino H.
Published: March 2009

Utilisant une technique de mesure électrochimique, les auteurs ont mesuré les coefficients globaux de transfert de matière entre une sphère solide et un liquide, l'une ou l'autre de ces phases étant soumise à un mouvement sinusoïdal alternatif.

l'intensité des transferts est fortement accrue pendant la pulsation; elle s'avèrve indépendante de la technique d'agitation utilisée, et ceci à moins de 10% près.

Dans le cas de la vibration de la sphère, les équations de transfert s'écrivent:

Il est important de souligner que l'exposant du facteur caractéristique de la vibration est égal à celui obtenu pour des transferts en convection forcée dans le cas d'un écoulement permanent. Cependant l'hypothèse de l'état quasi stationnaire n'est pas valable, l'intensité de transfert mesurée étant supérienre d'au moins 25% à la valeur théorique.
Evaporation rates of liquid hydrocarbon spills on land and water
Authors: Mackay Donald , Matsugu Ronald S.
Published: March 2009

The mass and heat transfer processes occurring during the evaporation of liquid hydrocarbon spills on land and water are described and equations developed to enable the liquid temperature and evaporation rate to be predicted. Experiments on the evaporation of cumene, water and gasoline are described and the evaporation mass transfer coefficient correlated with the wind‐speed, liquid pool size and the vapour phase Schmidt Number. Good agreement is obtained between experimental and computed cumene temperature and evaporation rates. Comparison of the correlation with flat plate mass transfer correlations shows satisfactory agreement and suggests that turbulent transfer occurs, the rate being enhanced by the liquid surface roughness. The more complex problem of estimating evaporation rates of hydrocarbon mixtures is discussed briefly.
Simulated random packing of equal spheres
Authors: Tory E. M. , Church B. H. , Tam M. K. , Ratner M.
Published: March 2009

PACS, a computer program to simulate very slow settling of rigid equal spheres into a randomly packed bed, is described. Simulated packings of 6,000, 10,000, and 15,000 spheres are anisotropic. Mean void fraction is 0.42 and mean number of nearest neighbours 6.0. There are numerous cases of four spheres arranged in a tetrahedron, but no larger ordered regions. These findings, plus local voidage, distribution of circles in a section, angular distribution, and radial distribution are compared to theoretical and experimental results.
Coalescence and break‐up in dilute polydispersions
Authors: Shiloh K. , Sideman S. , Resnick W.
Published: March 2009

Functional relationships for coalescence rate dependence on drop size and hold‐up were derived via the collision rates and coalescence efficiency. Experiments in an agitated vessel indicated the coalescence rate to be controlled by the viscous flow regime and, per unit drop concentrations, to be proportional to the third power of the sum of the diameters of the two coalescing drops. By combining the experimentally known coalescence rate dependence on drop diameter with the independently determined dependence of the latter on the dispersed phase hold up, the breakup rate was found to depend on d2.0.
Viscous flow across banks of circular and elliptical cylinders: Momentum and heat transfer
Authors: Masliyah Jacob H.
Published: March 2009

Numerical solutions of the Naviet‐Stokes equation have been used to extend Kuwabara's zero voiticity cell model to flow past banks of circular and elliptical cylinders for Reynolds numbers up to 50 and for porosities between 0.4 and 0.8. Total drag coefficients are presented. The complete energy equation was also solved numerically for Prandtl numbers of 0.7 and 7. Good agreement between existing experimental results for heat transfer in banks of circular cylinders and the numerical solution was obtained. In the assemblage, the ratio of the total heat transfer to pressure drop was highest when the main flow was parallel to the major axes of the elliptical cylinders. In all cases considered, the ratio of the minor to the major axis was 0.2.
Symposium on application of pulse techniques to kinetic measurements: Influence of cycling on the rate of oxidation of SO2 over a vanadia catalyst
Authors: Unni M. P. , Hudgins R. R. , Silveston P. L.
Published: March 2009

Feed composition cycling of the catalytic oxidation of SO2 to SO3 in an isothermal, differential reactor was studied using an industrial vanadia catalyst. Reaction was carried out at 405°C using square‐wave cycles of SO2, O2 and N2 at pressures close to atmospheric and at constant total molar flow through the reactor. Significant increases were found in the rate of oxidation of SO2 over steady‐state values, depending upon the choice of both amplitude and period.

Some preliminary interpretation of these results is provided.
A new class of solution methods for multicomponent, multistage separation processes
Authors: Boston J. F. , Sullivan S. L.
Published: March 2009

A new algorithm was developed for the solution of the equations that describe multicomponent, multistage separation processes operating at steady state. The algorithm is based on the use of newly defined energy and volatility parameters as the primary successive approximation variables. A third parameter was defined for each stage as a unique combination of the liquid and vapor phase rates and the temperature, and the quasi‐Newton method of Broyden was employed to iterate on these parameters. The exceptional stability of the new algorithm in very difficult cases, as well as its efficiency in easy cases, are demonstrated using a variety of example problems.
Time‐optimal control of linear systems
Authors: Luus Rein
Published: March 2009

A useful procedure for the solution of time‐optimal control problems for linear systems is presented. The procedure consists of a direct search method for the determination of the best diagonal weighting matrix used in a Liapunov function for the system. The control policy chosen to minimize the forward difference of the Liapunov function yields very rapid approach to the origin.

Numerical results are presented for a linear six‐plate gas absorber to show the feasibility of the proposed method. Even in the presence of disturbances the system can be taken to and kept at the vicinity of the origin.
Predicting the required liquid throughput from the capsule velocity and capsule pressure gradient in capsule pipelines
Authors: Kruyer Jan , Ellis H. S.
Published: March 2009

A model has been developed describing the relationship between the capsule velocity, the capsule pressure gradient and the bulk velocity. It allows the prediction of the bulk velocity when both the capsule velocity and the capsule pressure gradient are known and thus enables the calculation of the amount of liquid required to move a given quantity of solids. It also allows the prediction of the capsule pressure gradient when both the capsule velocity and the bulk velocity are known, but the measurement of these velocities must be very accurate before the capsule pressure gradient can be predicted to a reasonable accuracy. A Reynolds number developed for the model indicates whether the liquid surrounding the capsules is in laminar flow (Rec > 1000) or inturbulent flow Reo > 1000).
Peak heat fluxes on thin horizontal ribbons in submerged water jets
Authors: Andrews D. G. , Rao P. K. Mohan
Published: March 2009

This paper reports experimental observations on peak (critical) heat fluxes on stainless steel ribbons exposed to flow currents under submerged distilled water jets at subcooled and saturated conditions at near atmospheric pressures. A theoretical correlation is proposed based on certain modifications to the treatment of pool boiling hydrodynamic theory.
On the choice of methods for the prediction of the water‐activity and activity coefficient for multicomponent aqueous solutions
Authors: Sangster James , Lenzi Fabio
Published: March 2009

Some of the various methods of predicting thermodynamic properties of multi‐component aqueous solutions have been critically examined and interrelated. Recommendations are made for the best choice of method according to data available, accuracy required and type of solute.
Modelling of liquid‐liquid extraction columns: Use of published model correlations in design
Authors: Korchinsky W. J.
Published: March 2009

Design of several liquid‐liquid extraction columns — packed, pulsed‐packed, pulsed‐plate, Oldshue‐Rushton columns and the rotating disc contactor — was attempted utilizing available correlations for drop size, holdup of dispersed phase, flooding velocities, mass transfer coefficients and axial mixing coefficients. Correlations in many cases were vaguely defined and often based on very limited data. Results indicated that for given flow rates and extraction efficiency, the height of a packed or Oldshue‐Rushton column must be considerably greater than the predicted minimum heights of the other three columns, which were comparable considering the limited data utilized in the developed correlations. A critical evaluation of the correlations should be carried out to guide the further experimental effort required to confirm the utility of the axial dispersion model in liquid‐liquid extraction column design. Extension of the theory to include drop size variation is highly desirable.