bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transient and steady state, free and natural convection, numerical solutions: Part I. The isothermal, vertical plate
Authors: Hellums J. D. , Churchill S. W. 
Published: June 2004

AbstractNumerical values are presented for the transient velocity field, temperature field, and local heat transfer coefficient. These results were obtained by solving the partial differential equations describing the conservation of mass, momentum, and energy on an IBM‐704 computer with finite difference methods in time‐dependent form. The computed values for short times agree very well with the analytical solution for conduction only, and the limiting values for long time agree well with previous solutions for the steady state. The existence of a temporal minimum in the heat transfer coefficient is confirmed. The time required for the heat transfer coefficient to approach its steady state is shown to be less than previously predicted.
Burnout conditions for flow of boiling water in vertical rod clusters
Authors: Becker Kurt M. 
Published: June 2004

AbstractThis paper deals with a new concept for predicting burnout conditions for forced convection of boiling water in fuel elements of nuclear boiling reactors.The concept states the importance of considering the ratio of heated channel perimeter to total channel perimeter.The perimeter ratio concept was arrived at from an experimental study of burnout conditions in rod clusters consisting of three rods of 13 mm. outside diameter and 830 mm. heated length. Data were obtained for pressures between 2.5 and 10 kg./sq. cm., surface heat fluxes between 50 and 120 W./ sq. cm., mass flow rates between 0.03 and 0.33 kg./sec., and steam qualities between 0.01 and 0.52.The rod clearance for the experiment were 2 and 6 mm. The diameter of the channel was 41.3 mm. Additional runs were also performed after unheated displacement rods were introduced in the channel. The rod clearance in this case was 6 mm.In the ranges investigated the measured burnout steam qualities at the outlet of the channel decrease with increasing heat flux and decreasing pressure. Furthermore it has been found that the influence of rod clearance is, in the range investigated, of small significance for engineering purposes.It has also been observed that the present burnout steam quality data for the rod clusters are much lower than those earlier obtained for round ducts. This may be explained physically by means of the perimeter ratio concept.It has also been found that the surface shear stress distribution around the channel perimeter and especially the position of maximum shear stress is of great importance for predicting burnout conditions for flow in channels.Finally the new method has helped in understanding and interpreting experimental results which earlier may have seemed inconsistent.
Estimation of enthalpies: Multicomponent hydrocarbon mixtures at their saturated vapor and liquid states
Authors: Stevens W. F. , Thodos George 
Published: June 2004

AbstractBased on the data reported by Rossini et al. (9) analytical expressions have been developed for the calculation of enthalpies at zero pressure as functions of temperature for normal paraffins ranging from methane through octane. The coefficients of these equations have been found to correlate linearly with molecular weight, thus allowing the enthalpy relationships for hydrocarbons heavier than octane to be determined by extrapolation. The enthalpy of mixtures at zero pressure can then be obtained by combining the enthalpies of the individual components on an additive basis, weighted by the mole fractionsCorrections due to nonideal gaseous behavior have been developed in equation form from the work of Lydersen, Greenkorn, and Hougen (7) in terms of the reduced temperature TR and the critical compressibility factor zc of the substance. These corrections have been developed for both the saturated vapor and saturated liquid states and can be applied to the determination of the enthalpy of mixtures at these conditions. The results of this method have been compared with the experimental enthalpy data available for three ternary mixtures and were found to be in excellent agreement.
Flow and diffusion characteristics of alumina catalyst pellets
Authors: Robertson J. L. , Smith J. M. 
Published: June 2004

AbstractSteady state constant pressure diffusion measurements were made on a series of alumina pellets using the nitrogen‐helium system at 1 atm. and 80°F. The pellets were prepared from the same alumina powder but compressed to different densities. Pore size distribution data indicate that all the pellets had approximately the same micropore sizes and volume, but different macropore volumes. Flow measurements with nitrogen were also carried out for the same pellets over a pressure range, up to 1 atm. The data show that the pellet density, or macropore volume, has a pronounced effectOn the basis of a simplified model of the pellet, path lengths were evaluated from the flow data. On the assumption that the diffusion path length is the same, a method is presented for predicting diffusion rates. The results so computed are independent of the path tortuosity. The method correctly evaluates the effect of pellet density on diffusion, but measured rates are 40 to 80% of the calculated values.
Selectivity in experimental reactors
Authors: Tichacek L. J. 
Published: June 2004

AbstractUnpacked pipes or tubes, commonly called flow reactors, are often desirable for carrying out homogeneous reactions. Unless these reactors are properly designed and operated, axial mixing will alter both the rate of conversion and the distribution of products from successive reactions. Several hypothetical reaction schemes are analyzed here to show how axial mixing affects the production of an intermediate. The analysis represents mixing by an axial diffusion coefficient and is valid when mixing is not extreme. Results from several particular cases are compared, showing that reactor‐product distribution is generally distorted in proportion to a reactor Peclet number. G. I. Taylor's theory of axial mixing is used to relate this Peclet number to the physical characteristics of the reactorAlthough the effects of axial mixing are concluded to be negligible in most commercial or large‐scale equipment, they are serious in the case of experimental or pilot‐scale apparatus. Charts are drawn to illustrate design problems for these reactors.
Problem of solidification with Newton's cooling at the surface
Authors: Hrycak Peter 
Published: June 2004

AbstractAn approximate solution to the problem of freezing of an isotropic, semi‐infinite slab is proposed for the situation where Newton's cooling at the surface of the slab applies. Comparison with the existing exact solution shows the approximate solution to be practical.The heat‐balance integral method is used with the assumptionof linear temperature distribution in the frozen zone and of a parabolic temperature profile in the liquid zone. The final expression for the depth of solidification, however, seems to be only little affected by the particular temperature profiles chosen.
Numerical and experimental study of damped oscillating manometers: I. Newtonian fluids
Authors: Biery John C. 
Published: June 2004

AbstractThe time‐dependent behavior of Newtonian oscillating manometers was studied experimentally and mathematically. The manometers were simulated by numerically integrating the axial component of the equation of motion in cylindrical coordinates. Modifications in the driving‐force term were made to include end effects of surface tension and flow reversal. The integrations showed that the velocity profiles in the manometer were not parabolic and contained many maxima and minima, particularly when the fluid had a low viscosity. Good agreement was obtained between experimental and simulation frequencies and damping factors.
Adiabatic, evaporating, two‐phase flow of steam and water in horizontal pipe
Authors: Pike Ralph W. , Ward Henderson C. 
Published: June 2004

AbstractThe adiabatic, evaporating, two‐phase flow of steam and water in horizontal pipe including the critical flow was successfully described by a system of nonlinear differential equations which include different phase velocities, fluid acceleration, wall shear forces, interface shear forces, and mass and energy transfer between the phases. The solution of the differential equations by the method of Runge‐Kutta was facilitated with a high‐speed digital computer. Experimental data were obtained which included void fraction measurement by X‐ray attenuation and showed that the theoretical equations described the complex flow phenomena to ± 10% when radial temperature gradients were small. Design charts based on the numerical solution of the theoretical equations are presented for rapid evaluation of the flow variables for the system steam‐water including critical flow for inlet pressures from 30 to 150 lb./sq.in.abs., mass flow rates per unit area from 300 to 1,000 lb./sq. ft. sec., andL/Dratios from 25 to 1,000. The critical flow is defined as the maximum flow rate for a given pressure at the point of initial vaporization andL/Dratio.
Simultaneous radiative and convective heat transfer in an absorbing, emitting, and scattering medium in slug flow between parallel plates
Authors: Chen John C. 
Published: June 2004

AbstractThe problem of coupled radiation and convection to a medium in slug flow between infinite, parallel plates was formulated in terms of discrete fluxes. Steady state, uniform heat input, and gray boundaries were assumed. The effects of absorption, emission, scuttering, and flow were taken into account. For the general case where all these effects are present, it was necessary to approximate the fourth‐order temperature term by a truncated Taylor series. This approximation was not necessary for the special case where conductivity of the medium is negligible.Approximate, analytical solutions in closed form for profiles of temperature, radiant fluxes, and heat fluxes were obtained for both the special case and the general case. Sample results are presented, showing the effects of convection, absolute temperature, absorption coefficient, scattering coefficient, and wall emissivities. The two cases of equal wall temperatures and unequal wall temperatures were both examined.It was found that for a medium with properties approximately representative of those for air carrying a suspension of dust or mist, radiation can account for 60 to 95% of total heat transfer in the temperature range of 900° to 2,800°R. It was also found that for some situations the scattering phenomenon can have a much greater effect on heat transfer than the absorption and emission phenomena.
Phase‐volume relationship at the point of phase inversion in liquid dispersions
Authors: Yeh George C. , Haynie Fred H. , Moses Rex A. 
Published: June 2004

AbstractThe point of inversion of a water‐in‐oil type of dispersion to an oil‐in‐water type is investigated for several water‐oil systems by studying the volume ratios of the phases in relation to their physical properties. The point of inversion for each system of an immiscible organic liquid and water and organic liquid mixture and water is obtained by varying the phase‐volume ratios and determining the type of dispersion after complete mixing. The effects of temprature, interfacial tension, and density are found to have no correlation generally applicable to the systems studied. A volume‐viscosity relationship is found to exist within limits. This correlation is that the phase‐volume ratio at the point of inversion is equal to the square root of the ratio of teh viscosities of the respective phases at the interface. The theoretical aspects of this relationship are studied along with its limitations.
Asymptotic solution for combined free and forced convection in vertical and horizontal conduits with uniform suction and blowing
Authors: Carter Leo F. , Gill William N. 
Published: June 2004

AbstractSignificant changes in heat and momentum transfer rates can be caused by finite interfacial velocities and external field forces. This study considers the nonlinear problem of combined free and forced convection in vertical and horizontal two‐dimensional conduits with finite transverse velocity.Similarity transformations for the temperature function have been found which reduce the energy, momentum, continuity, and state equations for these configurations to nonlinear systems of two coupled ordianary differential euqations. These equations are solved by approximate methods to give Nusselt numbers and friction factors as well as velocity and temperature profiles.Stream to wall temperature differences increase with suction and decrease with injection. The effects of interfacial velocity on temperature profiles and heat transfer increase dramatically with Prandtl number. Because blowing and suction strongly affect temperature profiles they substantially modify natural convection effects in vertical flows. Suction creates steeper transverse temperature gradients and accentuates buoyancy effects in vertical flows. Conversely injection flattens temperature profiles and thus decreases the influence of buoyancy on the velocity field.
An analytical study of heat and mass transfer in multiparticle systems at low Reynolds numbers
Authors: Pfeffer Robert , Happel John 
Published: June 2004

AbstractThis investigation was undertaken to obtain an analytical solution to the problem of predicting particle‐to‐fluid heat and mass transfer rates in multiparticle systems at low Reynolds numbers. The energy equation based on the free surface model was solved by expanding the fluid temperature distribution in even powers of the spherical angle and by assuming that the fluid properties remain relatively constant with temperature. Solutions were obtained for Peclet numbers between 0.1 and 100 and fractional void volumes between 0.4 and 1.0. They show that the average Nusselt or Sherwood number in a bed of particles is a function of both the fractional void volume and the Peclet number, the effect of Peclet number decreasing as the bed becomes more concentrated in the low Peclet number range. A plot of the results in terms of the j factor vs. the Reynolds number shows good agreement with published experimental mass and heat transfer data and indicates that the j factor is not independent of the Schmidt or Prandtl numbers at low Reynolds number, low Peclet number flow.
Vapor‐liquid equilibria for aqueous sulfuric acid
Authors: Gmitro John Irving , Vermeulen Theodore 
Published: June 2004

AbstractBecause the precise composition of the vapor phase over aqueous sulfuric acid is not accessible experimentally a method is described for calculating the partial pressures of water, sulfuric acid, and sulfur trioxide starting from liquid‐phase partial molal thermodynamic quantities. Graphs and tables are provided which give the partial pressures from −50° to 400°C., between 10 and 100 wt. % acid.
Generation of waves in the concurrent flow of air and a liquid
Authors: Cohen Leonard S. , Hanratty Thomas J. 
Published: June 2004

AbstractIf air flows concurrently with a liquid, there are critical air velocities above which two‐dimensional and three‐dimensional waves appear at the interface. The physical process responsible for these transitions is as follows: The disturbance in the velocity field in the air caused by these waves gives rise to pressure and shear stress variations over the wavy surface. Pressure variations in phase with the wave slope and shear stress variations in phase with the wave height transmit energy from the air flow to the liquid film. If the rate at which energy is transmitted to the waves by these mechanisms is not larger than the rate of viscous dissipation in the liquid, the waves will decay.The model of the gas flow proposed by Miles and Benjamin is used to calculate shear stress and pressure variations over the wavy surface. The agreement between predicted and measured critical air velocities, wave lengths, and wave velocities is good.
Pseudocritical constants
Authors: Reid R. C. , Leland T. W. 
Published: June 2004

AbstractPseudocritical rules provide a means to determine reduced properties for mixtures so that pure component corresponding states correlations may be used to estimate mixture properties. The most common pseudocritical rules are examined and shown to stem from a common base. Points of divergence as well as similarity are pointed out in tracing out the development of the rules. Reduction of all rules to simpler forms is made and criteria attached to allow one to determine when such simplifications are justifiable. All rules reduce to Kay's rule in certain limiting cases.
Measurement of some basic parameters in two‐phase annular flow
Authors: Quandt E. R. 
Published: June 2004

AbstractThe vertical upflow of air‐water mixtures in the dispersed‐annular flow regime has been studied in a ¼ × 3‐in. rectangular channel. Dye injection into the wall film was used to determine film and gas core properties along with the rate of droplet interchange between the core and the film. Visual observations demonstrated that the most important characteristic of this flow regime is the surface waves generated by the gas flow over the liquid film. Despite the surface waves, these data indicate that the liquid film approximately follows the generalizedu+—y+relationship for turbulent pipe flow. The droplet motion is discussed in terms of transverse diffusion and momentum transfer.
Estimation of vapor and liquid enthalpies
Authors: Yen Lewis C. , Alexander R. E. 
Published: June 2004

AbstractThe Lydersen‐Greenkorn‐Hougen (L‐G‐H) charts correlating the isothermal pressure effects on enthalpy for pure compounds based on a modified corresponding states principle have been improved with the aid of reliable literature data. To facilitate machine computations, the improved charts, divided into the superheated vapor region, the subcooled liquid region, the saturated vapor, and the saturated liquid lines, have been expressed in analytical forms. This correlation reproduces the literature enthalpy data including those in the critical region for pure compounds with an average deviation of about 5 B.t.u./lb. It can also be used for the estimation of enthalpies of nonpolar mixtures with satisfactory results.
An analysis of fully developed laminar flow in an eccentric annulus
Authors: Snyder William T. , Goldstein Gerald A. 
Published: June 2004

AbstractAn analysis is presented of fully developed laminar flow in an eccentric annulus. An exact solution for the velocity distribution is presented. From this solution may be obtained expressions for local shear stress on the inner and outer surfaces of the annulus, friction factors based on the inner and outer surfaces, and the overall friction factor. Curves of these data are presented covering a range of eccentricity values and radius ratio values.
Pressure drop studies in a plate heat exchanger
Authors: Smith Vernon C. , Troupe Ralph A. 
Published: June 2004

AbstractRecent studies on heat transfer in plate heat exchangers have pointed out the need for quantitative expressions for pressure drop in this type of apparatus. This paper presents the results of experimental studies to obtain pressure drop relationships useful in plate heater design.A plastic prototype of a commercial model (Chester‐Jensen) exchanger was fabricated and used to obtain entrance, exit, crossover, ribbed section, and overall pressure drops as a function of velocity with water as the fluid. These individual losses were combined into an expression for overall pressure drop for a series plastic plate pack having any number of plates and employing any fluid.Overall pressure drop data on a commerical Chester‐Jensen Model HTF plate heater were available from several heat transfer studies reported previously. The data for series patterns were resolved by inserting overall pressure drop, physical properties of the fluid, and number of plate passes into the general form of the equation derived for plastic plates and by solving for a new set of constants. The resulting computer‐derived expression was found to predict series pressure drops in the apparatus to ± 10%.From a similar approach it was possible to correlate the overall pressure drop data for the heater for looped flow patterns.
Heat transfer characteristics of boiling nitrogen and neon in narrow annuli
Authors: Lapin Abraham , Totten H. C. , Wenzel L. A. 
Published: June 2004

AbstractThe boiling characteristics of liquid neon and nitrogen in vertical annuli ranging between 0.006 and 0.080 in. wide were studied. The centre tube wall, submerged to various depths, formed the boiling surface. Observations suggested a convective heat transfer mechanism, and correlation by a Dittus‐Boelter equation form proved successful.
Determination of the activity coefficient of a volatile component in a binary system by gas‐liquid chromatography
Authors: Chueh Chun F. , Ziegler Waldemar T. 
Published: June 2004

AbstractThe gas‐liquid chromatographic (GLC) method of measuring the activity coefficient of the solute in a binary system has been extended from infinite dilution to the finite concentration range. An equation is presented relating the retention volume of the injected solute sample to the equilibrium solute concentration present in the column. This relation permits determination of the activity coefficient of the solute. Based on the experimental results obtained from the study of the two binary systems, benzene in diethylene glycol at 50°, 70°, and 90°C. and n‐hexane in 1,2,4‐trichlorobenzene at 30°C., the activity coefficients of the solute measured by the GLC method were found to agree within about ±5% with those obtained by the static equilibrium method.
Flash x‐ray analysis of fluidized beds
Authors: Romero Jacob B. , Smith Don W. 
Published: June 2004

AbstractFlash X‐ray radiography was used to study the internal structure of fluidized beds. Basic data were obtained on the density distribution and on void shapes, sizes, and velocities within an air‐sand bed. The data obtained, in general, support the view of fluidized beds as consisting of liquidlike emulsions through which voids rise. Density measurements and void characteristics were in agreement with the two‐phase flow theory and with more recent theories of fluid bed flow. Void velocities and shapes agreed with recent predictions that the dense phase behaves as a liquidlike emulsion of zero viscosity and surface tension.
Dynamics of bullet shaped bubbles encountered in vertical gas liquid slug flow
Authors: Street James R. , Tek M. Rasin 
Published: June 2004

AbstractA theoretical analysis is presented of the liquid film flowing around long, bullet shaped, gas bubbles which characterize the slug‐flow regime in two‐phase flow through vertical pipe. Integral mass and momentum balances on the liquid film allow the prediction of gas bubble shape, liquid holdup around the bubble, wall shear stress acting on the liquid film, and velocity profiles in the liquid film. These predictions are in good agreement with data available in the literature.
The numerical solution of boundary‐layer problems
Authors: Fussell D. D. , Hellums J. D. 
Published: June 2004

AbstractA new method for numerical solution of boundary‐layer problems has greater applicability as well as greater speed and accuracy than the several previously proposed methods. The method uses the Goertler‐transformed equations and a nonlinear finite‐difference procedure. In most earlier work on difference methods the equations have been linearized at each step parallel to the boundary. The method of treatment of the boundary conditions on the equation of change for energy or mass transfer is shown to have an important influence on accuracy, and a new, more accurate method of treating boundary conditions involving the normal derivative is presented.Typical complete solutions are compared with the several methods. The solutions include both similar and more general flows up to separation, as well as coupling between the momentum and energy‐balance equations.