bluuebunny/crossref_metadata_2025_split huggingface dataset:
A comparison of the performance of techniques for direct, on‐line optimization
Authors: Edler J. , Nikiforuk P. N. , Tinker E. B. 
Published: March 2009

AbstractThe performance of a number of well known optimization techniques has been compared with that of recently developed weighted‐mean random techniques, in the context of on‐line process control applications. It was found that one variation of the random technique compared favorably with the well known pattern search technique of Hooke and Jeeves in finding the maximum on simulated process response functions.The study was performed by representing the processes by mathematical expressions. The effects of multidimen‐sionality, irregular response surfaces, scaling errors, and process noise were simulated in the tests that were performed for the comparisons.
Ternary systems: A numerical method for calculation of vapor‐liquid equilibrium data from total pressure measurements
Authors: Ramalho R. S. , Bui V. T. 
Published: March 2009

AbstractA numerical method for calculation of vapor‐liquid equilibrium data for ternary systems, from total pressure measurements, is developed. The proposed method is applied to the ternary systems benzene‐n heptane‐n propanol and acetone‐methanol‐water.
Annular flow of two immiscible liquids I. Mechanisms
Authors: Hasson D. , Mann V. , Nir A. 
Published: March 2009

AbstractA study was made of the flow mechanisms of two immiscible liquids with a small density difference introduced at a horizontal‐pipe inlet in initial concentric flow. Extent of the annular flow, its break‐up mechanisms and the subsequent flow patterns encountered were investigated with the aid of high‐speed photography.Annular‐flow break‐up was found to occur by one of two mechanisms: collapse of the core‐liquid by varicose Rayleigh‐type waves or rupture of the top‐wall liquid‐film, attenuated by the ascent of the lighter core‐liquid. Flow patterns observed after break‐up involve fine dispersions, slugs or stratified layers. Charts mapping flow‐pattern zones show conditions under which annular‐flow holds over a considerable extent.
Studies on cocurrent gas‐liquid flow in helically coiled tubes. II. Theory and experiments on turbulent mass transfer with and without chemical reaction
Authors: Banerjee Sanjoy , Scott Donald S. , Rhodes Edward 
Published: March 2009

AbstractPure carbon dioxide was absorbed into distilled water and sodium hydroxide solution, in cocurrent two phase annular flow in helically coiled tubes in order to measure physical and chemical mass transfer coefficients and interfacial areas. (k*La) was correlated by the pressure drop in the test sections and interfacial areas were found to vary with the liquid phase energy dissipation.According to a new theory, (k*L) has been shown to be a function of the root mean square vorticity near the interface. The root mean square vorticity has been related to the pressure drop, gas density, liquid flow rate and liquid velocity. The physical mass transfer coefficients theoretically predicted are in good agreement with experimental results.
Modeling and stability of catalytic fixed bed reactors
Authors: Hlavacek Vladimir 
Published: March 2009

AbstractThe existence of a multiple or oscillatory condition in a packed bed reactor, with a strongly exothermic reaction, is reviewed. The following cases are discussed: simultaneous heat and mass transfer within and outside a catalyst particle, axial mixing in tubular reactors and a recycle reactor. It is shown that the condition describing multiplicity can be estimated solely on the basis of the CSTR analysis. A correspondence between stability and parametric sensitivity is presented.
Chlorine exchange resins, effects of resin formulation on exchange properties
Authors: Dewar E. J. , Wayman M. 
Published: March 2009

AbstractChlorine 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

AbstractA 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

AbstractThe 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.
Residence time distribution functions for stirred tanks in series
Authors: Stokes R. L. , Nauman E. B. 
Published: March 2009

AbstractMany 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

AbstractIncreasing 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

AbstractResults 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

AbstractAn 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

AbstractA 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

AbstractGroup 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractDensities, 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractCarbon dioxide removal by aqueous ethylenediamine has been studied in 4‐inch diameter absorption and stripping columns packed with 1/2‐inch Intalox saddlesMass 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 betterEquilibrium 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 strippingThe 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

AbstractA 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

AbstractThe 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 examinedThe 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

AbstractSome 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

AbstractThe 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

AbstractA 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

AbstractPower 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