bluuebunny/crossref_metadata_2025_split huggingface dataset:
An investigation of absorption‐reaction of carbon dioxide in liquid diethanolamine by the direct chromatographic perturbation method
Authors: Barrere C. A. , Deans H. A. 
Published: June 2004

AbstractPhysical and chemical equilibrium in the carbon dioxide‐diethanolamine system was studied by the direct chromatographic method. The amine was present as a coating on the inside of a capillary tube. Carbon dioxide‐helium mixtures were passed through the capillary until equilibrium was attained, at which time a sample of C14O2 was injected into the carrier stream. The retention volumes (carrier volume flowed at peak appearance) of concentration and radioactive perturbations were measured at four temperatures and five carrier gas compositions. Static equilibrium solubility of carbon dioxide in the amine was also measured to verify the dynamic results.The theory of reactive chromatographic flow was extended to this system. The concentration and isotope retention volumes, which theory predicts to be different functions of carrier composition, were shown to be self‐consistent. The static solubility data was also seen to be consistent with theory and with the direct chromatographic data. The liquid phase of the system appeared to be ideal except at infinite dilution of carbon dioxide. The apparent departure from ideality could be explained in terms of weak ionization of reaction products. Electrical conductivity measurements tend to confirm this hypothesis.Both physical and chemical equilibrium constants for carbon dioxide were obtained at the four temperatures. Gross heat of reaction and apparent ionization heat were also obtained.
Laminar liquid jet diffusion studies
Authors: Duda J. L. , Vrentas J. S. 
Published: June 2004

AbstractA rigorous analysis of jet hydrodynamics is used to develop a technique for determining diffusion coefficients from laminar liquid jet absorption experiments, and the influence of the jet fluid mechanics on the absorption process is clarified. The new technique is used to determine the diffusivities of carbon dioxide, oxygen, argon, nitrous oxide, ethylene, and propylene in water within the temperature range 25° to 40°C.A critical analysis of available diffusivity data for these gases indicates that there is no conclusive evidence that demonstrates the existence of a significant interfacial resistance in uncontaminated laminar jet experiments. In addition, comparison of existing data shows that the commonly accepted diffusivities for the oxygen‐water system may be significantly higher than the actual values. It is concluded that the laminar jet experiment is a rapid, accurate method of obtaining diffusion coefficients of dissolved gases in liquids.
The mechanism of heat transfer in a spray column heat exchanger
Authors: Letan Ruth , Kehat Ephraim 
Published: June 2004

AbstractTemperature profiles of dispersed kerosene and water were measured in a spray column heat exchanger, 15 cm. in diameter and 160 cm. long. Dispersed packing of drops and narrow temperature ranges were used. The flow rates used were 0 to 50 liters/min. of water and 5 to 40 liters/min. of kerosene. The physical picture that emerges from the temperature profiles is that heat is transferred from fully mixed drops to fully mixed wakes while the wakes are formed, by shedding and renewal of elements of wakes in most of the column and by complete mixing of all streams at the water inlet at the top of the column. Mathematical equations were developed from the physical model. The volume of the wakes and the rate of shedding of wake elements were estimated from the temperature profiles and were used to calculate the temperature profiles for this and for other studies. The agreement of the calculated profiles with the experimental data is very good.
Turbulent heat transfer in drag reducing fluids
Authors: Wells C. Sinclair 
Published: June 2004

AbstractAn analysis is presented which extends the analogy between energy and momentum transport for turbulent pipe flow of purely viscous fluids to include drag reducing, non‐Newtonian fluids. The correlation by Meyer is used to predict friction factor and sublayer thickness for the drag reducing fluids. The use of the friction factor correlation with the heat transfer analogy makes it possible to predict heat transfer rates from simple measurements of pressure drop and flow rate for the drag reducing fluids. Some recent experimental data for two effective drag reducing fluids and for water are compared with the predicted heat transfer rates, and the mean deviation in Nusselt number is found to be +8.5% for all of the data. The heat transfer analysis predicts a reduction in Nusselt number accompanying a reduction in friction factor for a given Reynolds number and for Prandtl numbers greater than 1.
Fluid flow through woven screens
Authors: Armour James C. , Cannon Joseph N. 
Published: June 2004

AbstractA packed bed model has been adopted to develop a general correlation applicable to the flow of Newtonian fluids through all types of woven metal screens. Both of the main theoretical approaches to studying pressure drop in packed systems have been used by visualizing the screen as a collection of submerged objects with surface area to unit volume ratioafor laminar flow, and as a bundle of tubes of diameter D for turbulent flow. In the usual manner viscous and inertial energy losses are added to give an expression for the total pressure loss. Rearrangement of the general equation to the form of a friction factor yields a unique definition of the Reynolds number for screensNRe= ρu/μa2D. Procedures are described for collection of pressure drop‐velocity data for the flow of nitrogen and helium through plain square, full twill, fourdrinier, plain dutch, and twilled dutch weaves. The data are used to derive a viscous resistance coefficient α = 8.61 and an inertial resistance coefficient β = 0.52. The validity of the correlation equation is tested by using additional data from the literature. The correlation successfully predicts pressure drop for a Reynolds number range of 0.1 to 1,000, void fractions from 0.35 to 0.76, screen pore diameters from 5 to 550 μ, mesh sizes from 30 to 2,400 wires/in., and surface area to unit volume ratios from 1,200 to 29,000 ft.−1.
Density and pressure fluctuations in gas fluidized beds
Authors: Winter Olaf 
Published: June 2004

AbstractA Bench‐scale size fluidization system was constructed for the purpose of conducting experiments to determine density and pressure fluctuations in gas fluidized beds. Density fluctuations and bubble sizes were measured with a photocell device and β‐ray absorption. Pressure fluctuations were determined with a conductivity cell. The frequency distributions of the density and pressure fluctuations and bubble sizes were determined as functions of several variables. They could be described by dimensionless coefficients and X2‐distributions with different degrees of freedom. Such variables as distance from the gas distribution plate, bed height, particle size, gas flow rate, and internal screens were considered.
Similarity type of solutions of the turbulent boundary layer equations for momentum and energy part I: An analysis of some existing solutions
Authors: Telles A. S. , Dukler A. E. 
Published: June 2004

AbstractThe law of the wall, the law of the wake, and the velocity defect law have been proposed as similarity types of solutions of the turbulent boundary layer momentum equation. Spalding proposed an approximation of the same type as the solution of the energy equation. This study shows these laws to be derivable from a small‐perturbation type of solution of the general boundary layer equations for turbulent flow. The limiting conditions where each can be expected to be valid are clearly demonstrated. In particular, the law of the wall is shown to be the zeroth‐order solution of the momentum equations when the solution is expressed in the form of a small‐perturbation expansion. The first‐order perturbation is shown to generate a relationship similar to Coles' law of the wake. Likewise, Spalding's approximation is shown to be the zeroth‐order small‐perturbation type of solution of the energy equation.
Mass transfer to falling films: Part I. Application of the surface‐stretch model to uniform wave motion
Authors: Howard D. W. , Lightfoot E. N. 
Published: June 2004

AbstractA method is developed for predicting rates of gas absorption into laminar rippling films in terms of the surface velocities. The description is an extension of the surface‐stretch model of mass transfer (1) and is therefore useful for cases of high Peclet number. The description can be used with any of the presently known hydrodynamic models of rippling films and with any future models which may be developed, provided they satisfy two relatively nonrestrictive conditions: (1) the ripples are of a two dimensional nature, being of constant thickness in the direction normal to their direction of propagation, and having no velocity components in this transverse direction; and (2) the ripples propagate at constant celerity and with constant shape. It can be used for both traveling and standing waves and can be extended to describe the effects of high net‐mass transfer rates and combined diffusion and chemical reaction.
Thermodynamic equilibrium in the vapor phase esterification of Acetic acid with ethanol
Authors: Hawes Russell W. , Kabel Robert L. 
Published: June 2004

AbstractA study of vapor‐phase equilibrium in the reaction system acetic acid‐ethanol–ethyl acetate‐water has been made including an evaluation of past investigations, a calculation of equilibrium constants from thermal data, and new experimental determinations utilizing gas chromatography in a novel method. It was found that the magnitude of the thermodynamic equilibrium constant and its true variation with temperature are appreciably different than previously indicated. This is due to the failure of earlier workers to adequately account for competing reactions, primarily the dehydration of ethanol to ethyl ether. Equilibrium constants were obtained at 100, 120.8, and 170°C. for the ethanol dehydration reaction. Equilibrium positions of the esterification reaction have been determined accurately at the same three temperatures, however the corresponding values of the thermodynamic equilibrium constant remain imperfectly specified because of uncertainty concerning the acetic acid association equilibrium.
Heat transfer coefficients and circulation rates for thermosiphon reboilers
Authors: Beaver P. R. , Hughmark G. A. 
Published: June 2004

AbstractHeat transfer coefficients and circulating data were obtained for a single tube thermosiphon reboiler operated under vacuum and at atmospheric pressure. The results are compared with existing correlations. an analysis is presented for local heat transfer coefficients in the single phase and two‐phase regions.
Adsorption rate constants from chromatography
Authors: Schneider P. , Smith J. M. 
Published: June 2004

AbstractA new method for determining adsorption equilibrium constants, rate constants, and intraparticle diffusivities is described and applied for the adsorption of ethane, propane, and n‐butane on silica gel. The method rests upon recently developed theory for relating the moments of the effluent concentration wave from a bed of adsorbent particles to the rate constants associated with the various steps in the overall adsorption process. It is necessary to operate at concentrations of adsorbable gas such that the adsorption isotherm is linear. However, it is possible to take into account effects of longitudinal dispersion and diffusion to the particle surface as well as the intraparticle processes of diffusion and adsorption on the pore surface.The method gave reasonable values for intraparticle diffusivities and adsorption rate constants. Intraparticle diffusion was a major resistance for all particle sizes studied and for the largest size (R = 0.50 mm.) this step controlled the overall rate.From the constants determined chromatographically it is possible to predict breakthrough curves for the adsorption of these hydrocarbons on silica gel. The predicted curves agree well with experimentally established breakthrough curves.
Continuous‐phase mass‐transfer coefficients for liquid extraction in agitated vessels
Authors: Schindler Harvey D. , Treybal Robert E. 
Published: June 2004

AbstractArea‐free continuous‐phase mass‐transfer coefficients for continuous flow of ethyl acetate (dispersed) and water (continuous) were measured in a 9.5 in. diameter baffled vessel, agitated with 3 and 5 in. diameter flat‐blade turbines, and with the 3 in. turbine in the absence of baffles. Specific interfacial area was determined by a light‐transmission technique which permitted a vertical traverse of the vessel.The specific area is greatest, and mean drop diameter smallest, near the impeller. The mean area is lower than that predicted from existing correlations for batch operation in the absence of mass transfer. Continuous‐phase mass‐transfer coefficients increase with increased impeller Reynolds number and dispersed‐phase holdup, and are about 2.5 times larger in the unbaffled vessel at the same impeller power. The coefficients are generally larger than those predicted by existing correlations based on suspended solids, and it is suggested that this and the effect of holdup is the result of drop coalescence and redispersion, which causes a renewal of the continuous phase surrounding each drop. Rough estimates of the minimum coalescence frequency in the baffled vessel and application of the renewal concept to the data appear to confirm this view. Lack of information on circulation rates prevents immediate test of the data from the unbaffled vessel.
Sinusoidal and pulse response of a plate distillation column by reflux upset
Authors: Marino Pasquale A. , Perna Angelo J. , Stutzman Leroy F. 
Published: June 2004

AbstractA study was made to evaluate pulses as a forcing function on a 24‐plate distillation column. Pulses of two shapes, rectangular and displaced cosines, and of different widths were used as inputs to the reflux return line from the condenser to the column. The effect of the disturbance was a change in the liquid return rate which correspond to the shape and size of the pulse. The output responses of the system were temperatures measured at different times and at different plates in the column.Bode diagrams were plotted from the experimentally determined data. From these plots, it was determined that the system could be approximated by linear first‐order equatons. The time constants for the linear system were determined both by direct sinusoidal forcing and by pulse forcing. Pulse data were considered acceptable when the values of the time constant and the phase angle determined by the pulse compared favorably with those determined by steady state sinusoidal forcing.
Chromatographic study of surface diffusion
Authors: Schneider Petr , Smith J. M. 
Published: June 2004

AbstractA new method, based upon chromatography, was used to measure surface diffusion coefficients for ethane, propane, and n‐butane on silica gel. The diffusivities correspond to very low surface coverages (fraction of a monolayer of the order of 10−4) and hence should represent limiting values. A survey of available surface diffusion information, all at higher coverages, indicated that the results reported here are at the lower end of the range of diffusivities. The activation energy and heat of adsorption, for example, for n‐butane, were 4.4 and −7.8 k cal./mole, respectively.Surface diffusion was a significant fraction of the total intraparticle mass transport, in part because in the small pores in silica gel gas phase diffusion was solely by the Knudsen mechanism. For propane, surface migration was 73% of the total transport at 50°C. and 61.5% at 125°C.
Condensation from superheated gas‐vapor mixtures
Authors: Stern Frederick , Votta Ferdinand 
Published: June 2004

AbstractSuperheated mixtures of vapor and noncondensable gas were cooled and condensed in down‐flow inside a single tube vertical condenser, 0.995 in. I.D. and 3.5 ft. long. The systems studied were air‐water, carbon dioxide‐water and helium‐water. A bulk stream mixing probe was developed which enabled the measurement of point values of the stream temperature and partial pressure at various positions within the condenser. The Reynolds number range of the investigation was 5,700 to 34,000.A theoretical solution of the problem, using Bras' design method, was solved rigorously on a digital computer. Results indicated excellent agreement between the theoretical and experimental cooling paths and the required transfer area. The inclusion of the Ackerman correction factor (for the sensible heat carried by the diffusing vapor) into the calculation gave significantly better agreement for all cases tested.
Dispersion in developing velocity fields
Authors: Gill William N. , Ananthakrishnan V. , Nunge Richard J. 
Published: June 2004

AbstractConvective diffusion in laminar flows which develop from rest and in the velocity entrance region of tubes, is studied. Criteria for the validity of the simple dispersion model are established by comparison of analytical results with numerical experiments.It is found that the extent of dispersion is less in developing velocity fields than in those which are fully developed. This occurs because dispersion is enhanced by differences in the velocity of the fluid particles on a plane perpendicular to the main direction of flow. Such differences are greatest when the flow is fully developed.
Transient diffusion from a well‐stirred reservoir to a body of arbitrary shape
Authors: Ma Yi Hua , Evans Lawrence B. 
Published: June 2004

AbstractA theoretical study was made of transient diffusion to a body immersed in a finite volume of well‐stirred fluid. The major contribution of this work was the development of a technique for solving the problem for a three‐dimensional body of arbitrary shape. The solutions are in a form that is useful for determining diffusion coefficients insolids by means of the constant‐volume experimental technique.The partial differential equation coupled with the ordinary differential equation describing the diffusion process is transformed into a single integral equation in terms of the solute concentration in the reservoir. A numerical technique is then presented for solving the integral equation. Numerical solutions were computed for the three geometries that possess analytical solutions: the infinite slab, the infinite cylinder, and the sphere. By properly choosing the step‐size numerical results were easily obtained that agreed with the exact solution to four decimal places.New solutions were computed for two three‐dimensional geometries: the finite cylinder and the rectangular prism. A range of shape factors and ratios of the volume of the reservoir to that of the solid body were employed for each geometry. It was shown that by selecting the ratio of volume to external surface area as the characteristic length of each shape object, the solutions for all shapes were brought close together and were identical during the initial part of the transient.
Graphical calculation of multiple steady states and effectiveness factors for porous catalysts
Authors: Stewart Warren E. , Villadsen John V. 
Published: June 2004

AbstractSimple graphical methods are given for predicting the effectiveness factors of single reactions in particles of various shapes. A collocation procedure is used for small particles, and the known asymptotic solution is used for large particles. Multiple steady states and variable fluid properties can be handled directly. Examples are given for several nonlinear reaction rate laws.
The effect of pressure on the permeation of gases and vapors through polyethylene. Usefulness of the corresponding states principle
Authors: Stern S. A. , Mullhaupt J. T. , Gareis P. J. 
Published: June 2004

AbstractThe permeation of carbon dioxide through polyethylene membranes has been studied at pressures up to 54.4 atm. and at temperatures above and below the critical temperature of the gas (31.0°C.). The permeability coefficient is independent of pressure at the highest experimental temperature (61.0°C.), but becomes increasingly pressure‐dependent as the temperature is lowered. The principle of corresponding states can be used to correlate the solubility of both gases and vapors in polyethylene over a wide range of temperatures. This principle can also be invoked to obtain an upper limit for the penetrant pressure above which the permeability coefficient becomes pressure‐dependent. The effect of pressure on the permeability, solubility, and diffusivity of gases and vapors in polyethylene is discussed in some detail.
Axial dispersion in turbulent flow through standard 90 degree elbows
Authors: Cassell Robert E. , Perona Joseph J. 
Published: June 2004

AbstractAxial dispersion was studied experimentally for turbulent flow through a 1 1/4‐in. piping system containing 90 deg. elbows. The Reynolds number range was 15,400 to 96,555. The imperfect pulse tracer technique was used with the axial dispersion numbers being obtained from the difference in variances of concentration‐time curves observed at two points in the system.Elbows interconnected by short lengths of pipe with each succeeding one reversed so as to cause a change in the direction of flow, increased axial dispersion by 35 to 61% over that expected for straight pipe, while the same elbows turned so as to form a helix decreased the dispersion substantially; however, the amount of axial dispersion was still 8 to 22% greater than that observed for straight pipe.The equivalent lengths of the elbows depend upon both their arrangement and the Reynolds number. Closely placed, helically arranged elbows required equivalent lengths of from 2.9 to 5.1 diam., while a reversed arrangement required 6.9 to 11.6 diam. Elbows separated by a developing length and randomly arranged yielded an equivalent length range of 3.6 to 10.6 diam. The geometical l/d ratio of the elbows used was 2.05.
Diffusion and solution of gases into thermally softened or molten polymers: Part II. Relation of diffusivities and solubilities with temperature pressure and structural characteristics
Authors: Durrill Preston L. , Griskey Richard G. 
Published: June 2004

AbstractSolubilities and diffusivities of various gases (helium, nitrogen, carbon dioxide, argon, neon, krypton, and monochlorodifluoromethane) in molten or thermally softened polymers (polyethylene, polypropylene, polyisobutylene, polystyrene, and polymethylmethacrylate) have been correlated with structural characteristics, temperature, and pressure. Temperature dependence of both Henry's Law constants and diffusivities were of the Arrhenius equation form. No appreciable effect of pressure was found for either Henry's Law constants or diffusivities up to 300 atm. Earlier correlations for Henry's Law constants in solid polymer systems were found to be inapplicable for molten and thermally softened polymers. New correlations were developed individually for the latter systems. The correlating factor used was the gas Lennard‐Jones force constant. Existing correlations for diffusivities were also found not to apply to molten and thermally softened systems. New correlations were again developed on an individual polymer basis. These related diffusivity to gas Lennard‐Jones collision diameter or molecular diameter. Generalized correlations were also developed that held for a number of polymers. These were for both Henry's Law constants and diffusivities.
Maximum temperature rise in gas‐solid reactions
Authors: Luss Dan , Amundson Neal R. 
Published: June 2004

AbstractA shell progressive kinetic model is used to determine the temperature rise in a spherical pellet for a gas‐solid diffusion controlled reaction. The effects of heat and mass transfer resistances in the gas film as well as inside the pellet are investigated. The predicted temperature rise may be severe enough to cause sintering to catalyst pellets in which reactions such as combustion of coke occur.