bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Impact of Water Abstraction on River Mutonga Discharge Over the Last 30 Years
Authors: Mwirigi Padiel , Jane Kagendo , Karienye David 
Published: February 2024

The declining water levels among rivers flowing through Tharaka Nithi County have been a major concern in the region for the last 30 years. The decline has adversely affected environmental sustainability, water resources, agriculture and the ecosystem. Understanding the relationship between rivers, change of climate and human activities are essential challenging areas. The research aimed to assess the impact of changed rainfall pattern and amount to the declining water levels in Mutonga River over years from 1990 to 2020 and it contribution to the changing water levels in river Mutonga. An exploratory survey and a correlational study were used to compile the data for this analysis. Three regional NEMA officials and three regional water resources authority officials were also surveyed, along with 270 residents in the River Mutonga area. The samples were based on 30% as per Mugenda Mugenda samples analysis. The rainfall and temperature data was acquired from the regional meteorological department based in Embu town. Data on river discharge was acquired from regional water resource authority (WRA) based in Meru town. The result may also recommend suitable practices for management of water resources and come up with disaster control measures in water sector. The local community may also benefit from the study by getting the right information on better methods of conserving water resources, the findings and recommendations from the study may be used as basis for future research related to this study. From the findings, results show that river Mutonga flows has been decreasing over the last 30 years, water abstraction trend has been rising over the entire period in three decades causing a tremendous decline in river discharge. climatic changes have been noted in the region with rainfall amount dropping significantly and temperatures increasing, this has led to decline of the river discharge due reduced rainwater adding to the rivers and increased evaporation rates which leads to loss of water from rivers to the atmosphere. The result from the research may be used to enlighten the County Government of Tharaka Nithi, in making decision, especially in development projects implementation and in the strategic plans of the County Government.
Mass transfer in packed beds
Authors: Fahien R. W. , Smith J. M. 
Published: June 2004

AbstractAlthough considerable work has been done on the problem of heat transfer radially in fixed beds through which gases are flowing, the data available for mass transfer are limited to one pipe size and one packing size and refer to average diffusivities for the entire bed. The present study was undertaken to determine: (1) diffusivities over a range of pipe and packing sizes and (2) the effect of radial position in the bed.The measurements were made by introducing carbon dioxide into an air stream and analyzing the resultant mixture at various positions in the bed downstream from the point of injection. Pipe sizes of 2, 3, and 4 in. were packed with spherical particles of 5/32‐, 1/4‐, 3/8‐, and 1/2‐in. nominal diameter.The differential equation describing the concentration in a packed bed when diffusivity E and the velocity u are permitted to vary with radial position was solved by use of an I.B.M. card‐programmed calculator for the computations.The results show that the Peclet number Dpu/E increases from the center towards the wall of the pipe and that the increase is significant when Dp/Dt is greater than 0.05. Empirical correlations are then presented for both point Peclet numbers, which vary with radial position, and average Peclet numbers for the entire bed.The variations in Peclet number with radius can be explained in terms of the corresponding variation in void fraction for 81% of the radius of the bed. At modified Reynolds numbers above 40 to 100 the equation Pe = 8.0 + 100 (δ — δ0) correlates the effects of pipe and packing size and radial position. At radial positions greater than 0.81 wall friction influences turbulence conditions and the Peclet number.
Transport of momentum and energy in a ducted jet: II. Theoretical study of turbulent transport of momentum, energy, and matter in ducted coaxial streams
Authors: Alexander L. G. , Kivnick Arnold , Comings E. W. , Henze E. D. 
Published: June 2004

AbstractThis paper concerns the kinetics of the processes that take place when a high‐velocity jet of fluid mixes turbulently with a low‐velocity, induced stream of the same fluid in a duct of uniform diameter. Semi‐two‐dimensional solutions of the equations of transport involving two empirical coefficients were obtained by application of Reichardt's hypothesis and three assumptions: (a) a negligible fraction of the flow entity (energy, mass, or momentum) is lost at the wall and the presence of the boundary layer may be ignored, (b) the static pressure is uniform over a section of the duct, and (c) the turbulence pattern is similar to that in free jets except that the duct wall limits the growth of the scale of the turbulence. A mixing index, which is a measure of the degree to which the jet stream remains unmixed with the induced stream at any point, was defined and related to the geometry of the system and the flow parameters by means of the theoretical equation, and a method of evaluating the empirical coefficients for a typical case of momentum transport was described.
Upward cocurrent annular flow of air and water in smooth tubes
Authors: Calvert Seymour , Williams Brymer 
Published: June 2004

AbstractTwo‐phase fluid flow is distinguished from single‐phase flow in two respects: (1) the cross section for flow of either fluid is not defined by the conduit alone and (2) not only the extent but the manner of frictional energy exchange for each fluid depends on the individual rates of flow for both fluids. It was believed therefore that an empirical approach would not adequately describe the various situations encountered in two‐phase flow, and so study was undertaken to obtain some understanding of the mechanisms of the flow of liquid with a free surface and the momentum exchange between fluids at that surface. It resulted in the development of a method of predicting liquid holdup and pressure drop for flowing systems in which the liquid, lifted by the gas flowing as a central core, moves upward as an annular film along the pipe wall.In order to clarify the relationship of annular flow to the entire range of vertical two‐phase flow modes, a discussion of vertical two‐phase flow is presented, followed by an analysis of the special case of vertical, upward, annular flow; a description of the experimental work; and a comparison of experimental data with predictions.
Surface tension and the principle of corresponding states
Authors: Brock James R. , Bird R. Byron 
Published: June 2004

AbstractExperimental surface‐tension data for pure substances have been correlated successfully by the use of two recent modifications of the principle of corresponding states. The results are expressed in terms of simple analytical relations which allow one to calculate the surface‐tension curves either from the critical constants Pc, Vc, and Tc or from Pc, Tc, and the boiling point Tb and also provide a method for estimating critical properties from surface‐tension measurements. In addition, a method for estimating the surface tension of molten metals is suggested.
Turbulence in falling liquid films
Authors: Stirba Clifford , Hurt D. M. 
Published: June 2004

AbstractOn the basis of fluid dynamic and heat transfer studies on falling‐film towers by various investigators, it has been commonly accepted by most workers that the liquid flow is essentially streamline in nature for liquid‐film Reynolds numbers under 1,800 to 2,000; conseuquently it would be expected that the rate of physical gas absorption in such liquid films could be predicted directly from a knowledge of molecular diffusion rates.Measurements of the absorption of pure gases in falling liquid films at low Reynolds numbers substantiated the findings of other investigators that the mass transfer rates were manyfold greater than could have been predicted if molecular diffusion were the only transfer process. Increased interfacial area due to rippling of the liquid films could not account for the large increase in mass transfer rates found, and experiments with the addition of a dye stream to the liquid at the freer interface indicated turbulence.Dissolution rates of slightly soluble solids coated on the tube wall to liquid films were measured and showed that the liquid film was not in laminar flow even for Reynolds numbers as low as 300.An explanation is proposed which resolves these apparently conflicting results between momentum and heat and mass transfer, based on the fact that mass transfer measurements provide a more sensitive test for the presence of turbulence than do momentum or heat transfer measurements.
Perforated‐Plate extraction‐column performance and wetting characteristics
Authors: Garner F. H. , Ellis S. R. M. , Hill J. W. 
Published: June 2004

AbstractThe type of surface of the perforated plate influences the performance of a perforated‐plate column. Pilot plant data on a 4‐in column for the system toluenediethylamine‐water at 20°C. show that when the water phase is dispersed and the direction of mass transfer is from the continuous toluene to the dispersed water phase polyethylene plates give a continuous stream of droplets and a higher efficiency, but that when the direction of mass transfer is from the dispersed water to the continuous toluene phase the metal plates give the higher efficiency.
Dehydration of hydrazine by azeotropic distillation
Authors: Wilson R. Q. , Mink W. H. , Munger H. P. , Clegg J. W. 
Published: June 2004

AbstractA process was developed for dehydrating aqueous solutions of hydrazine by azeotropic distillation with aniline as an entrainer. The ternary system hydrazine‐water‐aniline, which contains the minimum‐boiling aniline‐water azeotrope and the maximum‐boiling hydrazine‐water azeotrope, was studied by fractionation analysis to determine the position of the ridge or distillation barrier in the vapor and liquid surface. The studies showed that the position and curvature of this ridge were favorable for the production, by rectification, of a solution richer in hydrazine than the azeotropic proportions. The process comprised three operations. Approximately 70% of the hydrazine charged to the system was dehydrated.Entrainers that form binary minimum‐boiling azeotropes with both hydrazine and water are discussed. Ternary systems with these entrainers have saddlepoint azeotropes that boil intermediate with respect to the other invariant components in the system.
Liquid films in viscous flow
Authors: Jackson Melbourne L. 
Published: June 2004

AbstractA trace of radioactive material dissolved in a liquid enables the thickness of a moving film to be determined by measurement of the radiation emitted. The method is rapid and accurate and an average thickness is obtained directly even though the surface of the film may be irregular. Six liquids, having viscosities ranging from 0.5 to 20 centipoises were observed in flow down the inner wall of a vertical tube. Liquids having viscosities of about 1 centipoise or less exhibit typical viscous behavior with respect to film thickness even when waves are present. Liquids having larger viscosities give values of the film thickness which are less than for true viscous flow. The departure from normal behavior increases with increasing viscosity and occurs only over the region where the liquid moves in wave flow. Surface tension is not a factor in either wave formation or wave flow.The wave motion appears at flow rates well within the viscous region and occurs when the Froude number exceeds unity. Equations derived for the viscous flow of liquid films on the inner wall of a vertical tube would be required where tube diameter is small or liquid viscosity large. Ordinarily the less complex equations for flow down a flat plate may be used. A theory of flow in the viscous region with waves present is suggested.
Chemical factors in propellant ignition
Authors: Cook Melvin A. , Olson Ferron A. 
Published: June 2004

AbstractA method of studying solid propellant ignition is described which utilizes detonating gas igniters. This article describes (1) conditions required for obtaining reproducible igniter systems and (2) results of application of the method to four well‐known rocket propellants in which various “chemical” and “thermal” effects were brought out by suitable variations in the initial pressure and composition of the detonating gas igniter. Successful application of the detonating‐gas‐igniter method requires the use of steady state detonation waves, i.e., waves in which the detonation head has attained a steady “size” and momentum. Experimental data are presented which show that detonation (following the initial predetonation buildup) must travel 40 to 50 cm. in a 1‐in. diam. steel tube before these steady state conditions are established in the systems studied.Results of studies by the detonating gas ignition method show that, besides the important purely physical effects of temperature and pressure, free oxygen and solid carbon in the igniter system are very effective in lowering the threshold ignition pressure. Moreover, increasing oxygen in the igniter markedly lowers the ignition time lag (τp) for appearance of an observable flame although it increases the time lag (τi) for appearance of reaction sufficient to cause the first measurable ionization in the reaction zone (τp ≫ τi). Although true flame‐ignition time lags were observed to be of the order of several milliseconds, reaction of the propellant was observed to start within 1 msec. (possibly immediately) after collision of the detonation wave with the propellant.The detonating gas method is shown to provide a reliable measure of the relative ignition sensitivities of various rocket propellants.
Estimation of ternary vapor‐liquid equilibrium
Authors: Severns W. H. , Sesonske Alexander , Perry R. H. , Pigford R. L. 
Published: June 2004

AbstractIsothermal vapor‐liquid equilibrium measurements were made at 50°C. for the ternary systems acetone‐methanol‐chloroform, acetone‐methanol‐carbon tetrachloride, and acetone‐methanol‐methyl acetate, by means of an improved vapor‐recirculation type of apparatus. The complete range of concentrations was investigated, including six of the seven constituent binary systems. Chemical methods, supplemented by density and refractive‐index measurements, were used for analysis.Results are presented in the form of activity coefficients γ as a function of various concentrations. Binary and ternary constants for the three‐suffix Margules equations were determined by plots of (log γ) / (1‐x)2 as a function of the mole fraction x. Such equations have been found to represent both the binary and the ternary data adequately except in the system containing both methanol and carbon tetrachloride. For these mixtures a simplified four‐suffix equation, including a single ternary constant, correlates binary and ternary equilibrium data.The data indicate that reliable estimates of ternary equilibria can be based on the assumption that the ternary constant C* is zero for mixtures in which all deviations from Raoult's Law are positive. This is interpreted as indicating that the probability of existence of trimolecular aggregates, two‐ or three‐component, in ternary solutions is no greater than the average of probabilities of existence of trimolecular aggregates in the constituent binary systems.Based on equations of the Margules type, a procedure is outlined for determining binary constants rapidly and for planning experiments whereby a ternary system may be completely investigated with the aid of very few measurements.The composition changes that the accompany differential distillation of the three ternary mixtures are described qualitatively in terms of the shape of the vapor‐pressure‐composition surfaces.
Flow of non‐newtonian fluids—correlation of the laminar, transition, and turbulent‐flow regions
Authors: Metzner A. B. , Reed J. C. 
Published: June 2004

AbstractAll available data on flow of non‐Newtonians in pipes have been correlated on the conventional friction factor — Reynolds number plot for Newtonian fluids. This correlation, theoretically rigorous in the laminar flow region, was tested with data on 16 different non‐Newtonian materials covering the 2.1 × 109 range of Reynolds numbers from 6.3 × 10−5 to 1.3 × 105. Pipe diameters varied from 1/8 to 12 in. As the correlation does not depend on the type of fluid encountered, it may be used with Newtonian and non‐Newtonian fluids alike.In spite of the great range of the available experimetnal data, further work is necessary in the transition and turbulent‐flow regions. No data at all were available on thixotropic, rheopectic, and dilatant fluids, and extension of the correlation to these materials should prove most illuminative from both theoretical and practical viewpoints.
Capacity factors in the performance of perforated‐plate columns
Authors: Hunt Charles D'Ancona , Hanson D. N. , Wilke C. R. 
Published: June 2004

AbstractA study was made of factors affecting the vapor‐handling capacity of perforated‐plate liquid‐vapor contacting columns. Vapor‐phase pressure drop across plates, liquid entrainment upward from plate to plate, and plate stability were investigated as functions of operational and geometric column parameters.Gas‐phase pressure drop across dry perforated plates was observed to follow functional relationships predicted from available information for single perforations. The presence of liquid on a plate increased the total pressure drop by the equivalent clear‐liquid head plus a small residue which is nearly constant for a given liquid.Entrainment was observed to be a function of column gas velocity, independent of gas velocity in the perforations. Weight rate of entrainment was also found to be proportional to the gas density, independent of liquid density, and inversely proportional to the liquid‐surface tension. For a given system, entrainment was observed to be proportional to approximately the third power of the group, gas velocity divided by the distance between the liquid surface and the plate above.The stability of perforated plates was observed to be adequate for many industrial and experimental applications, as also reported in recently published studies, but contrary to qualitative statements found in the earlier literature. Stability was found to increase with decreasing perforation diameter and decreasing total perforation area relative to column cross‐sectional area; to increase with greater gas density, liquid surface tension, and liquid wetting power; and to be virtually independent of liquid density and viscosity.Operating limits of vapor and liquid throughput are shown for a typical application of perforated plates in liquid‐vapor contacting columns.
Heat transfer in cylinders with heat generation
Authors: Topper Leonard 
Published: June 2004

AbstractThe prediction of temperatures has been studied for a tubular flow reactor when heat is generated at a rate which is a linear function of the local temperature. Analytical solutions are presented both for the case where the wall is isothermal and for the case where the exterior surroundings are isothermal and the heat transfer coefficient between the tube wall and the surroundings is constant. This analysis should be helpful for estimating local temperatures and also for predicting the transient response to changes in one of the independent operating variables.
Kinetics of the methane‐steam reaction
Authors: Akers W. W. , Camp D. P. 
Published: June 2004

AbstractA kinetic study was made of the reaction of steam and natural gas over a reduced nickel catalyst at a temperature range of 637° to 1,180°F.The rate of reaction is first order with respect to methane. The effect of temperature could be expressed by an Arrhenius type of equation. Both carbon monoxide and carbon dioxide are formed as primary reaction products.
Activity coefficients at infinite dilution
Authors: Gautreaux M. F. , Coates Jesse 
Published: June 2004

AbstractEquations are derived for obtaining activity coefficients at infinite dilution in binary systems by use of one of the following: (1) an isobaric temperature—liquid composition diagram, (2) an isobaric temperature—vapor composition diagram, (3) an isothermal pressure—liquid composition diagram, or (4) an isothermal pressure—vapor composition diagram. The derived equations are thermodynamically exact, and application involves no doubtful extrapolation of experimental data, as has heretofore been the case.Each equation involves the slope of one of the diagrams at the point corresponding to the pure component. Attention is called to the fact that data on the compositions of both the vapor and liquid phases in equilibrium are not required. Use of the equations is illustrated.
Pipe‐line design for non‐newtonian fluids in streamline flow
Authors: Christiansen E. B. , Ryan N. W. , Stevens W. E. 
Published: June 2004

AbstractA method is presented for determining the flow‐rate—pressure‐gradient relationship for the streamline flow of the large class of non‐Newtonian, nonthixotropic fluids to which the Powell‐Eyring equation applies. The general procedure and assumptions required in developing this method are the same as used in deriving the Hagen‐Poiseuille equation except that the Powell‐Eyring equation is used in place of Newton's equation to relate shear stress to shear rate.The method can be used to predict pipe‐flow pressure gradients from both precision viscometer data and pipe‐flow data. Its applicability is demonstrated for three typical non‐Newtonian fluids, 3% carboxymethylcellulose in water, 15% napalm in kerosene, and 33% hydrated lime in water.When used with pipe‐flow data, it resembles the method of Alves and associates, compensating for the inconvenience of an additional step in calculation procedure by providing a means of extrapolating beyond the range of the experimental data.The relationships developed facilitate the application of shear‐stress—shear‐rate data in the design of conduits for non‐Newtonian fluids.
Entrainment removal by a wire‐mesh separator
Authors: Carpenter C. LeRoy , Othmer Donald F. 
Published: June 2004

AbstractThe efficiency of a wire‐mesh separator as an entrainment eliminator has been experimentally determined in an evaporator employing a sodium chloride brine to trace the entrainment throughout the system. Superficial linear velocities have been tested with efficiencies ranging from less than 80% at lower velocities up to 99.9% at 17 ft./sec. Higher superficial linear velocities were explored, but the results were erratic, with reentrainment from the separator visually evident. The experimental data have been correlated by the assumption, and development, of a proposed mechanism for the capture of the entrainment particles by the wires in the separator. This mechanism is developed from a theoretical derivation by Langmuir and Blodgett used for correlating the stoppage of mist particles by the leading edges of airplanes and has been found to correlate the experimental data very well, so that predictions in unworked ranges may be made. The separator as applied in this experimental work behaved as an impingement‐type, inertial entrainment eliminator.The use of the presently developed equations permits the recommendation of specifications to be used in the fabrication of a separator for its most efficient performance if the nature of the entrainment and conditions of operation are known.