bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some aspects of fluid mechanics in chemical engineering
Authors: Sage B. H. 
Published: June 2004

AbstractThe prediction of the transfers of momentum, energy, and material is of ever‐pressing concern to the engineer interested in process design. Recently developed facts concerning the transport of momentum which are of particular use in predicting transfers of energy and material are reviewed, as well as the background of thermodynamics associated with transport processes. The more elemental relationships pertaining to thermal and material transfer in flowing streams are considered, and some of the interrelations of the transport processes are presented.
Experimental foundations of chemical engineering
Authors: White R. R. , Churchill S. W. 
Published: June 2004

AbstractFundamental knowledge consists of understanding not only the models which correlate and rationalized observations but also the quantity and quality of the observations. The degree of correlation attempted should be consistent with this quantity and quality.The scientist correlates and rationalizes observations primarily to broaden his general understanding of the physical universe, and his efforst at correlation are more often than not a way of speculating on the future experiments which should be undertaken to test his concepts. For this purpose he is often satisfied with accuracy to one order of magnitude. The engineer, faced with the design and operation of expensive equipment, is almost always interested in a much higher accuracy in his correlations.Virtually all existing data in the rate processes are forced into rationalizations based upon either potential‐difference or potential‐gradient models. The application of these models to systems of even relatively simple geometry gives rise to mathematical complexity beyond present analtic ability. Even so, our ability to measure and observe seems to be far below our ability to analyze. These two models have been used effectively in chemical engineering in the past and have served to organize a great deal of information in the rate processes. Present research efforts appear to be directed primarily toward filling in gaps in available data and in refining the application of the models. We seem to suffer from a lack of models to test and a lack of data designed to test critically the existing models. There is relatively little exploratory research in chemical engineering as compared, for example, to physics.When one views chemical engineering as a chain extending from economics, markets, mechanical design, process design, and process development to process research, the uncertainties inherent in some of the links easily involve variances of 50 to 80%. Under these circumstances it would appear that the present orientation of research is distributed much too heavily toward refinement of existing ideas and not nearly enough toward exploration.
Continuous stirred tank reactors: Designs for maximum conversions of raw material to desired product. Homogeneous reactions
Authors: Trambouze P. J. , Piret Edgar L. 
Published: June 2004

AbstractIt is shown in a series of illustrative examples how the conversion efficiency of many reactions can be markedly affected by the type of reactor used, even though the temperatures, catalyst, and basic kinetics are already fixed by the chemistry of the process.For such purpose graphical and analytic criteria are developed which permit the selection of a continuous stirred tank or tubular reactor system to obtain the most advantageous conversion of raw material to desired product. When a continuous stirred tank reactor process is preferable, the optimum number of reactor stages for maximum conversion is one. An example is given of a case where a combination of a continuous stirred tank and a tubular reactor is advantageous.A new graphical method of reactor design for simple or complex reactions is also introduced. This method utilizes continuous stirred tank reactor data directly rather than batch data or kinetics analyses.Reactions are classified according to the kinetic and stoichiometric characteristics which determine the allowable design procedures and the differences in the compostions paths occurring in batch, tubular, or continuous stirred tank reactors.The mathematical analysis of continuous stirred tank reactor systems for complex reactions leads to a set of difference equations. For cases of zero‐ or first‐order reactions these are readily solved as illustrated in examples, even when several independent components influence the reaction kinetics.
Transistion from laminar to turbulent flow in pipes
Authors: Ryan N. W. , Johnson M. M. 
Published: June 2004

AbstractIn pipeline design, for which one needs a means of ascertaining whether the flow will be laminar or turbulent, the Reynolds number is the criterion for Newtonian fluids. The principal purpose of this study was to formulate a more general criterion to characterize the flow regime and to test this form in application to non‐Newtonian fluids.Intuitive physical arguments suggested the use of a local stability parameter which is a function of the ratio of input energy to energy dissipation for an element of fluid. If the parameter is applied to a Newtonian fluid in laminar pipe flow, one finds that it has a maximum value of 0.385 times the critical Reynolds number, or 808. As the criterion is presumed to be general, it is inferred that the value of 808 defines the boundary between stable laminar and stable turbulent pipe flow for all fluids. The inference has been varified for several pseudoplastic fluids.
Heat transfer by radiation through porous insulations
Authors: Larkin Bert K. , Churchill Stuart W. 
Published: June 2004

AbstractRadiant transfer through fibrous and foamed insulating materials was investigated theoretically and experimentally. Transmission measurements were made under isothermal conditions with a black‐body source varying from 200° to 800°F. Bulk density and fiber and pore size were also varied. These data were interpreted successfully in terms of a simple theoretical model. The results provide design information and define the contributions of the several mechanisms of transfer.
Interfacial resistance due to thin films of alcohols and its effect on the rate of evaporation of water
Authors: Udani Lalit H. , Gordon Kenneth F. 
Published: June 2004

AbstractMeasurements were obtained of the interfacial resistance due to thin films of straight‐chain higher alcohols and their effect on the evaporation of water. This was done by passing preheated dry air at a constant rate over water in a beaker. Unlike previous studies both phases were stitted. Four alcohols, dodecyl, myristyl, cetyl, and stearyl, were studied. A large reduction in evaporation was observed when 0.00025 gm. of cetyl alcohol was added to 1 liter of water with gas‐liquid interfacial area of 0.2015 sq. ft. A much higher amount of stearyl alcohol, 0.0006 g., was needed for commensurate effect. Resistance due to films of dodecyl and myristyl alcohols was neglibible. For the most part cetyl alcohol is the most effective of those tested. Plots are given of the pseudo mass transfer coefficients and interfacial resistances as a function of the amount of the various alcohols.
Hypothetical standard states and the thermodynamics of high‐pressure phase equilibria
Authors: Prausnitz J. M. 
Published: June 2004

AbstractThermodynamic analysis of phase‐equilibrium data is necessary for testing such data, for extension to new conditions, and for purposes of correlation and prediction of phase‐equilibrium behavior. While such analysis is common for low‐pressure systems, it is rare for high‐pressure systems owing to difficulties encountered in the definition of standard states. For a gaseous solute in the liquid phase it is proposed that the standard state be taken as the hypothetical liquid at the temperature and total pressure of the solution. The properties of this standard state are specified by the temperature and total pressure and by the specific volume which the substance would have if it did not experience a phase change. This standard state is useful since it is not a function of the solution but only of the substance being considered. For a condensable component in the gas phase it is convenient for most purposes to define the standard state as the ideal gas at the temperature and total pressure of the solution, but to separate the effect of composition on the activity coefficient from that of pressure, it is proposed to define the standard state as the real hypothetical gas at the solution conditions. To illustrate these ideas, activity coefficients are computed for several high‐pressure systems, and it is shown how these activity coefficients may be used in the correlation, testing, and extension of high‐pressure phase‐equilibrium data.
Thermodynamic consistency of binary liquid‐vapor equilibrium data when one component is above its critical temperature
Authors: Adler S. B. , Friend Leo , Pigford R. L. , Rosselli G. M. 
Published: June 2004

AbstractMethods are developed for testing binary system phase‐equilibrium data for thermodynamic consistency when the more volatile component is above its critical temperature. The isothermal case with varying pressure and the isobaric case with varying temperature are considered individually. The rigorous form of the Duhem equation is employed rather than the simplified one, which for binary systems is inconsistent with the phase rule. Although derived for the specific case given in the title, the relationships developed are applicable to all conditions of binary systems. Sample calculations illustrating the methods are included.
Heat and mass transfer to decelerating finely atomized sprays
Authors: Manning W. P. , Gauvin W. H. 
Published: June 2004

AbstractThe rate of heat and mass transfer in the nozzle zone of water sprays produced by internal‐mixing pneumatic nozzles and hollow‐cone pressure nozzles was determined for both concurrent and crosscurrent drying air‐flow patterns. The Nusselt numbers for the evaporating drops were correlated by means of the equation proposed by Ranz and Marshall for stationary drops in a moving air flow. Methods of measuring the physical properties of the water‐air system were developed, and special attention was devoted to the determination of drop velocities and air humidity.
Velocity of large drops and bubbles in media of infinite or restricted extent
Authors: Harmathy Tibor Z. 
Published: June 2004

AbstractA new theory gives a simple method of calculating the terminal velocity of fluid particles moving in media of either infinite or restricted extent.Empirical and semiempirical formulas [Equations (27) and (30)] and a graph (Figure 6) over the interval 0 ≤ d/D ≤ 1.3 are shown to yield satisfactory results for gas or liquid particles moving in liquid media. In the case of liquid drops falling through gaseous media they give only a rough approximation.Graphs showing the variation of the drag coefficient (Figure 1) and the shape (Figure 2) of fluid particles with the Eötvös number are given. A semiempirical equation for the terminal velocity of solid spheres in restricted media has also been developed [Equation (24)].
Point source turbulent diffusion in a pipe
Authors: Flint Duane L. , Kada Hisao , Hanratty Thomas J. 
Published: June 2004

AbstractTurbulent diffusion from a small source located in the center of a 3‐in. pipe was studied. Hydrogen and carbon dioxide were mixed in air, and potassium chloride solution was mixed in water. Eddy diffusion coefficients calculated from the data are correlated by plotting (E)/(2aUc) vs. NRe. Differences from other data in the literature are discussed. The results could not be used for determining the form of the correlation coefficient because of inaccuracies in the measurements for small diffusion times.
Mass transfer in laminar—boundary‐layer flows with finite interfacial velocities
Authors: Acrivos Andreas 
Published: June 2004

AbstractAsymptotic expressions are presented in this paper for the mass transfer Nusselt number in both forced‐ and free‐convection laminar‐boundary‐layer flows with large interfacial velocities directed toward the surface. The analysis is valid for arbitrary surface geometries and includes transfer in a variable properties fluid. It is shown, in addition, how these asymptotic formulas may be used in conjunction with the Nusselt number for zero interfacial velocities to estimate the rate of mass transfer for the intermediate regions.
Liquid viscosities above the normal boiling point for methane, ethane, propane, and n‐butane
Authors: Swift G. W. , Lohrenz John , Kurata Fred 
Published: June 2004

AbstractViscosities, obtained with a falling‐cylinder viscometer, are presented for liquid methane, ethane, and propane from their normal boiling points to their critical points and for n‐butane from its normal boiling point to 100°C. The data of this study are compared with those of other investigators.The experimental viscosities of this study are correlated within ± 5% over the reduced‐temperature range from 0.65 to 0.95 by means of a modified Smith‐Brown correlation. The Grunberg‐Nissan equation for estimating the critical viscosity was tested with the experimentally determined critical viscosities of this study and was found satisfactory.
The viscosity of liquid mixtures
Authors: McAllister R. A. 
Published: June 2004

AbstractThe theory of viscosity of liquid mixtures presented here is based on Eyring's theory of absolute reaction rates. The most important conclusions drawn are that for liquids the free energies of activation for viscosity are additive on a number fraction or mole fraction basis and that interactions of like and unlike molecules must be considered. Methanol‐toluene, benzene‐toluene, and cyclohexane‐heptane systems were analyzed with a three‐body model and found to fit within the accuracy of the experimental data. Acetone‐water mixtures fit a four‐body interaction much better. Indications are that to describe acetone‐water mixtures well would require consideration of seven‐ or eight‐body interactions.
Flow patterns and mixing rates in agitated vessels
Authors: Norwood K. W. , Metzner A. B. 
Published: June 2004

AbstractMixing rates in agitated vessels are predicted through measurement of the flow patterns which determine them. These measurements suggest the use of a model that assumes that nearly all the mixing occurs in a small “perfectly mixed” region near the impeller, with flow throughout the remainder of the tank serving primarily to bring the fluid into this region of the impeller.On the basis of this model, equations were developed for relating volumetric flow rates, hence the mixing rates, to the operating variables. While the theory could be checked directly only to Reynolds numbers of slightly over 600 (owing to limitations of the experimental technique employed in this part of the mixing‐rate studies), the volumetric flow rates could be measured from Reynolds numbers of 36 to 1.7 × 104. The times required for completion of an acid‐base neutralization (terminal mixing) were also measured from Reynolds numbers of 1.6 to 1.8 × 105.Flat‐blade, dimensionally similar turbines with diameters of 2, 4, and 6 in. were used. Tank diameters ranged from 5.76 to 15.5 in. The baffle width equaled one tenth of the tank diameter in all runs. All the data were for Newtonian fluid systems, but the extension of this work to non‐Newtonian materials is discussed briefly.
Transient response study of gas flowing through irrigated packing
Authors: Demaria Francesco , White Robert R. 
Published: June 2004

AbstractThe transient response of a gas phase as it flows through an irrigated packed column can be interpreted as a distribution of time spent by the elements of gas as they flow through the bed.A step function in helium concentration was introduced in the entering air stream of a column packed with Raschig rings, and the outlet concentration was recorded with time. Water was used as the liquid phase. Size of Raschig rings, depth of bed, water and gas flow rates were the main variables investigated.The response curve for the gas reveals an increasing departure from uniform flow of the gas stream as liquid and gas rates are increased to flooding. The first and second moments of the time distribution give directly the porosity and the axial dispersion of the gas. These quantities have been found to be mainly dependent on liquid flow rates. The skewness which characterizes the weight that the various gas elements have on the dispersion about the average residence time has been found to give a convenient measurement of the uniformity of gas flow through the bed.
Mass transfer in semifluidized beds for solid‐liquid system
Authors: Fan Liang‐Tseng , Yang Yung‐Chia , Wen Chin‐Yung 
Published: June 2004

AbstractA new fluid‐solid contacting technique known as Semifluidization has been studied. Mass transfer data were obtained for a benzoic acid–water system, and correlations in terms of mass transfer factors and over‐all void fractions (for both packed and fluidized sections) are presented. Previous mass transfer correlations for fixed and fluidized beds are critically evaluated with respect to the limitation and applicability and are discussed in relation to semifluidized‐bed mass transfer correlations.
Detonation characteristics of hydrogen‐oxygen mixtures at high initial pressures
Authors: Gealer Roy L. , Churchill Stuart W. 
Published: June 2004

AbstractDetonation velocities of hydrogen‐oxygen mixtures were measured for initial pressures from 14.4 to 1,000 lb./sq. in. abs. and compositions from 40 to 80 mole % molecular hydrogen. Detonation and impact characteristics were computed for essentially the same range of conditions by the use of the elementary theory of detonation. Equilibrium compositions of hydrogen‐oxygen mixtures at pressures from 10 to 2,000 atm. and temperatures from 3,000 to 5,000°K. were included in the computations and have been filed with the American Documentation Institute. The effect of nonideal thermodynamic properties on the computed detonation velocities was considered.
A photographic study of pool boiling in the region of the critical heat flux
Authors: Cole Robert 
Published: June 2004

AbstractA photographic study was made to investigate the boiling phenomena in the neighborhood of the critical heat flux. The system consisted of an electrically heated zirconium ribbon, insulated on its underface, suspended in a pool of water at its saturation temperature. Measurements of bubble diameters, bubble positions relative to the heating surface, local bubble frequencies, and contact angles at known times intervals were obtained from the film. Results indicate that at high heat fluxes the primary forces acting on a bubble leaving the surface are the buoyancy and drag forces. A dimensionless relationship is developed relating bubble velocity, bubble diameter, and contact angle at breakoff. Drag coefficients for freely rising vapor bubbles a saturated liquid are found to be representable by the usual drag coefficient‐Reynolds number curves for solid bodies. Jakob's plot of bubble frequency vs. bubble diameter at breakoff is extended to high heat‐flux values, and a relationship proposed by Deissler at the critical heat flux is found to yield reasonable agreement with the experimental data.
Studies on axial effective thermal conductivities in packed beds
Authors: Yagi Sakae , Kunii Daizo , Wakao Noriaki 
Published: June 2004

AbstractThe axial effective thermal conductivities of packed beds were determined by measuring the axial temperature gradients at steady state, the heat being conducted in the direction opposite to that of air. The present experiments were carried out with the beds of glass beads, metallic balls, broken pieces of limestone, and Raschig rings, taken in separate experiments.It was found that the axial effective thermal conductivity increases more with the increase of air flow than it does in the case of radial conductivity. The axial effective thermal conductivity coincides with the radial conductivity when NRe → 0.
An experimentally verified theoretical study of the falling cylinder viscometer
Authors: Lohrenz John , Swift G. W. , Kurata Fred 
Published: June 2004

AbstractA theoretical analysis was made for laminar fluid flow in the annulus of a falling cylinder viscometer. A viscometer calibration constant was defined from the results of this analysis. This constant was expressed in terms of only the physical dimensions of the viscometer. The volues lidity of the theory was demonstrated by the agreement between predicted and experimental values of the viscometer constant.Methods of representing calibration data were compared. Temperature and pressure effects on the viscometer constants were related to the mechanical properties of the viscometer materials.The results of this investigation showed that the practical design of falling cyclinder viscometers is possible.
The role of porosity in filtration: IV. Constant pressure filtration
Authors: Tiller F. M. , Cooper H. R. 
Published: June 2004

AbstractCertain assumptions which have previously served as a basis for the conventional equations employed in constant pressure filtration are shown to be in error. It is demonstrated that the specific filtration resistance, the ratio of the mass of wet to mass of dry cake, and the rate of flow, q = dv/dθ, are not constant as has been assumed. In an example it is shown that q undergoes an eightfold variation as the liquid flows from the cake surface through to the medium.Since the product αq appears in the basic differential equation, incorrect values of q lead to errors in the calculated values of α arising from experimental data. The errors are significant when thick slurries are employed.New partial differential equations are presented for flow through compressible media in which q varies with cake thickness. Modifications of the conventional constant pressure equations are presented.
A study of hydrates in the methane‐propylene‐water system
Authors: Otto Frederick D. , Robinson Donald B. 
Published: June 2004

AbstractExperimental data are presented to show the points of incipient hydrate formation in the methane‐propylene‐water system. The addition of 1.4% propylene to methane lowered the equilibrium pressure 400 lb./sq. in. at 50°F. The locus of the four‐phase equilibrium consisting of hydrate, vapor, water‐rich liquid, and hydrocarbon‐rich liquid was determined. This was terminated by the appearance of a critical condition at 1,370 lb./sq. in. abs. and 69.3°F., where the vapor phase contained 34.8% propylene on a dry basis. Below this pressure the hydrate, vapor, water‐rich liquid equilibrium does not exist for solutions containing more than about 25% propylene. Solid‐vapor equilibrium ratios were estimated for propylene hydrates. The significant features of the phase diagrams for the system are discussed in some detail.
Effects of solids on turbulence in a fluid
Authors: Kada Hisao , Hanratty Thomas J. 
Published: June 2004

AbstractThe effect of solid particles on fluid turbulence was studied for fully developed flows of slurries in a vertical 3‐in. pipe for solids concentrations ranging from 0.13 to 2.5 volume %. Point source turbulent diffusion data in the slurry flows were compared with data for flows without solids present. The solids do not appear to have a large effect on the diffusion rate unless there is an appreciable average slip velocity between the solids and the fluid and unless the solids concentration is high enough.