bluuebunny/crossref_metadata_2025_split huggingface dataset:
Network rupture and the flow of concentrated polymer solutions
Authors: Tanner R. I. 
Published: June 2004

AbstractEntanglement theories for polymer solutions resemble those developed for solid rubbers. These rubberlike theories are extremely successful qualitatively; they give a good indication of the type of response observed experimentally in concentrated solutions. Quantitatively the theories are not so useful; in general they predict constant viscosities in simple shearing motions and ever‐increasing tensile stress in steady elongational flow.If it is supposed that the lifetime of the entanglements is limited partly by a maximum allowable strain magnitude, and that the network ruptures locally whenever this magnitude is exceeded, greatly improved quantitative predictions are observed. For polyisobutylene‐cetane solutions, where the critical strain magnitude appears to be about 3, excellent prediction of the steady shearing viscosity curve is available starting from the measured dynamical response to small sinusoidal strains and the critical strain magnitude. Normal stress effects are also well represented; in elongational flow the tensile stress shows a slight maximum. It thus appears that the notion of network rupture is useful in guiding the selection of continuum theories for polymer fluid description.
Effects of turbulence on the drag coefficients of spheres in a supercritical flow Ŕegime
Authors: Clamen Allen , Gauvin W. H. 
Published: June 2004

AbstractDrag coefficients of aerodynamically smooth spheres varying in diameter from 0.0625 to 1.004 in. and in density from 0.195 to 7.80 g./cc. were obtained at acceleration rates ranging from 120 to −30 ft./sq.sec. The particles were subjected to relative turbulence intensities of 7 to 35% and to ratios of Eulerian macroscale to particle diameter of about 0.4 to 5.Quantitative measurement of particle drag coefficients was made possible by the use of a new particle tracing technique which permits the resolution of time to the nearest tenth of a millisecond. The resulting data extend farther into the supercritical flow regime than any other measurements previously reported.The variation in drag coefficient with Reynolds number indicates a continuous alteration in the flow pattern around a sphere in this region. The effect of turbulence is, essentially, to increase supercritical drag, although this effect was found to diminish with increasing Reynolds number. Possible mechanisms for the effects of Reynolds number and turbulence on the particle drag coefficient are suggested.
Experimental determinations of the molar heat and entropy of adsorption and the activity coefficient of the adsorbed phase for the methane‐ethane‐silica gel system
Authors: Masukawa Shigehiko , Kobayashi Riki 
Published: June 2004

AbstractCalculations of the molar heat and entropy of adsorption for pure methane and pure ethane on silica gel at 25°C. show the heterogeneity of the adsorbent when plotted as functions of the spreading pressure. Plots are given for the activity coefficient of methane and ethane in the adsorbed phase based on experimental data for the entire range of compositions at 25°C. up to a maximum pressure of 1,400 lb./sq.in.abs. Similar results were obtained at 5, 15, and 35°C. The activity coefficients deviate from unity at intermediate compositions.
The fluid hydrates of methylene chloride and chloroform: Their phase equilibria and behavior as influenced by hexane
Authors: Tester J. W. , Wiegandt H. F. 
Published: June 2004

AbstractThermodynamic properties pertaining to phase equilibria in the binary‐fluid hydrate systems, methylene chloride‐water and chloroform‐water, and the ternary hydrate system, methylene chloride‐chloroform‐water, were measured. Total vapor pressure data were recorded as a function of temperature over a range of −3 to + 10°C. Quadruple locus measurements of the ternary four‐phase equilibrium, L1‐L2‐H‐G, and isobaric studies of the ternary system chloroform‐methylene chloride‐water, support the existence of a solid solution hydrate between methylene chloride and chloroform. The addition of the nonhydrate former, hexane, to the methylene chloride‐water system lowered the isobaric critical decomposition temperature of the hydrate.
Laminar velocity profiles in developing flows using a laser doppler technique
Authors: Berman Neil S. , Santos Valerio A. 
Published: June 2004

AbstractA laser doppler flowmeter is used to obtain velocity profiles in circular glass tubes downstream from a plug composed of brass screens. The apparatus for measuring point velocities of particles suspended in a fluid is described. Measurements were made very close to the plug at Reynolds numbers of 16.5, 47, and 274, and the flow development followed down the tube. The results show that the entrance flow development is dependent on the inlet profile shape and the Reynolds number for Reynolds numbers below 300.The flow development at Reynolds numbers less than 300 was considerably slower than that predicted by the boundary‐layer solution of the equations of motion starting with a flat profile.
Heat transfer from a cylinder in an air‐water spray flow stream
Authors: Mednick R. Lawrence , Colver C. Phillip 
Published: June 2004

AbstractForced convection heat transfer from vertical cylinders normal to an air‐water spray flow stream was measured over an air velocity range from 60 to 140 ft./sec. and a water spray density range from 0.03 to 0.50 lb.m/(min.) (sq. in.). Local heat transfer coefficients were determined at 15 deg. intervals around the circumference of both a 1.5 and a 1.0 in. diam. cylinder. It was found that the addition of 0.426 lb.m/(min.) (sq. in.) of water spray to a 133 ft./sec. air stream raised the stagnation point heat transfer coefficient from 45 to 1,650 B.t.u./(hr.) (sq. ft.) (°F.). Similar intensification was found for other angles around the cylinder circumference; however, the magnitude decreased with increasing distance from the stagnation point. Local heat transfer coefficients were normalized with respect to their corresponding stognation point values and plotted parametrically as a function of angle and air velocity. These profiles showed that the normalized heat transfer coefficients decreased with increasing air velocity at angles other than the stagnation point. Average cylinder heat transfer coefficients were calculated from the air‐water data and two correlations were obtained relating these coefficients to the air and the water spray Reynolds number.
A thermodynamic equation relating equilibrium vapor‐liquid compositions and enthalpy differences in isobaric multicomponent systems
Authors: Tao Luh C. 
Published: June 2004

AbstractA rigorous and simple thermodynamic equation relating equilibrium vapor‐liquid compositions and the phase enthalpy differences for a binary, isobaric system is extended to multicomponent systems. An analysis is made to indicate the potential applications of computing the latent heat of vaporization directly from the isobaric vapor‐liquid equilibrum data and testing the consistency of phase composition and enthalpy data.
A simple solution for boundary layer flow of power law fluids past a semi‐infinite flat plate
Authors: Hsu Chen‐Chi 
Published: June 2004

AbstractThe steady, two‐dimensional, incompressible laminar boundary‐layer flow of power law fluids past a semi‐infinite flat plate is studied analytically by the method of series expansion and the method of steepest descent (Meksyn's method). The shear stress of the fluids considered is proportional to the nth power of the velocity gradient. The solution obtained is a series of gamma function with the coefficient being a function of the material constant, n. The first ten terms of the series solution are then considered for the sum to determine the velocity gradient at the plate, fηη(0). The results obtained for fηη(0) and the coefficient of skin friction are in excellent agreement with the numerical solutions available in the range of 0.1 ≤ n ≤ 2.5.
Newtonian jet stability: The role of air resistance
Authors: Fenn Robert W. , Middleman Stanley 
Published: June 2004

AbstractThe stability of high speed laminar Newtonian jets is studied as a function of ambient air pressure. For Weber numbers less than 5.3 (based on air density) air pressure has no effect on stability. Ambient viscosity, through the effect of shear stresses acting on the jet surface, gives rise to the maximum in the breakup curve. For large Weber numbers ambient pressure effects can alter, and eventually control, the appearance of the maximum.
The effects of internal mass transfer on the hydrogenation of benzene over nickel‐alumina catalyst
Authors: Jiracek Frantisek , Horak Josef , Pasek Josef 
Published: June 2004

AbstractThe influence of mass transfer on reaction kinetics, within the porous structure of a catalyst, was investigated during the hydrogenation of benzene. The temperature range for a nickel catalyst at atmospheric pressure was 99 to 160°C. The rate equation and the apparent activation energy on a cylindrical catalyst pellet (4.5 mm. in diameter and 5.5 mm. in height) and on the catalyst particles (0.5 to 0.63 mm. in diameter) were evaluated.The effect of internal diffusion on the dependence of the reaction rate, on the temperature, and on the partial pressures of benzene and hydrogen was satisfactorily explained by means of theoretical relations. The values of the effective diffusion coefficient of benzene were compared by calculating the kinetic data and temperature difference in the cylindrical pellet.
Effects of transpiration and changing diameter on heat and mass transfer to spheres
Authors: Brian P. L. T. , Hales H. B. 
Published: June 2004

AbstractMass transfer to spheres suspended in an agitated liquid has been studied both experimentally and theoretically. Finite‐difference solutions are obtained for mass transfer from a sphere to a fluid flowing past it in steady viscous flow. The effects of a transpiration velocity at the surface of the sphere and of a continuously changing sphere diameter are included. A normalized presentation of these effects is quite insensitive to the bulk flow Peclet number. When these theoretical corrections for transpiring and shrinking spheres are applied to the mass transfer data for ice spheres that are melting in an agitated brine bath, the corrected mass transfer coefficients are brought into agreement with a generalized correlation published elsewhere. This agreement suggests that the theoretical results apply, with reasonable accuracy, to a shrinking and transpiring sphere that is suspended in a turbulent liquid.
Crystallization kinetics of pure and binary melts
Authors: Kirwan D. J. , Pigford R. L. 
Published: June 2004

AbstractAn absolute rate theory based on a plausible model of the activated state, was developed for the interfacial kinetics of crystal growth from the melt. Except for liquid metals the theory predicts the growth rates of pure materials within about an order of magnitude. A microinterferometric technique was employed to observe liquid compositions near the faces of crystals growing from binary melts. For the simple eutectic system composed of salol and thymol, the theory represents the composition and temperature dependence of the growth rate.
Mass and heat transfer relations in evaporation through porous membranes
Authors: Findley M. E. , Tanna V. V. , Rao Y. B. , Yeh C. L. 
Published: June 2004

AbstractThis study concerns rates of evaporation and mass transfer of water vapor from a heated salt solution through a water repellent porous membrane to a cooled water condensate. This transfer is a result of temperature differences and corresponding vapor pressure differences across the membrane. Three groups of experiments were carried out which indicate that the major factor influencing the rates of transfer is diffusion through a stagnant gas in the membrane pores. However, an equation considering film heat transfer coefficients, membrane thermal conductivity, and an empiricial correction based on temperature driving force appears to be necessary for representing all the data. The empirical correction appears to be related to internal condensation and possibly diffusion along surfaces.
Acetone photolysis: Kinetic studies in a flow reactor
Authors: Matsuura Takeshi , Cassano A. E. , Smith J. M. 
Published: June 2004

AbstractThe photodecomposition of acetone vapor was studied in a tubular flow, differential reactor at atmospheric pressure and from 82 to 112°C. The products included significant amounts of biacetyl along with carbon monoxide and ethane. A rate equation was developed from a sequence of elementary reactions believed to explain the photolysis of acetone. The effects of light intensity and acetone concentration, indicated in the derived rate equation, were confirmed by the data.The rate is less than first‐order with respect to acetone, and this is believed to be due to reformation of stable acetone molecules by deactivation of CH3COCH3*.
Profiles of laser‐created cavities on metal surfaces
Authors: Deming John L. , Weber James H. , Tao Luh C. 
Published: June 2004

AbstractMetal surfaces of titanium, aluminum, copper, lead, and zinc were irradiated by a 25 joules pulsed laser with an energy flux ranging from 106 to 108 cal./(sq.cm.) (sec.). The resulted cavities were sectioned, polished and measured to compare with the isotherms computed from several heat conduction models. Reasonable agreement was found between the experimental cavity diameters at the interface and those calculated from the disk source model. Also, a graphical correlation between the cavity depth and its interface diameter is presented.
Experimental and theoretical investigation of purification in a column crystallizer of material with impurities of the eutectic forming type
Authors: Albertins Rusins , Powers J. E. 
Published: June 2004

AbstractA theoretical analysis of the operation of a Schildknecht type of column crystallizer is presented and simplified to three special cases. Experimental determinations were made of concentration profiles established during the purification of benzene with cyclohexane as impurity under steady state, batch conditions of operation. Benzene containing 34 to 500 ppm. cyclohexane was obtained by processing feed material with 5,000 to 30,000 ppm. cyclohexane. It was found that experimental data obtained under conditions of normal operation are well correlated by theoretical expressions if it is assumed that the crystals are not pure but contain cyclohexane at the level of 34 to 100 ppm. It was further established that the resistance to mass transfer between the liquid which adheres to the crystals and the wash liquid is negligible in comparison to backmixing effects as represented in the model by an eddy diffusion term. Smooth operation of the column was obtained at crystal rates below a limiting upper value and at oscillation frequencies above a lower limit.
Heat transfer and pressure drop for nitrogen flowing in tubes containing twisted tapes
Authors: Kidd George J. 
Published: June 2004

AbstractHeat transfer and pressure‐drop studies were made on a series of electrically heated tubes containing full‐diameter, full‐length twisted tapes. The A nickel tubes had a nominal inside diameter of 0.4 in. (10.1 mm.) and a heated length of 12 in. (30.5 mm.). Nitrogen at 200 lb./sq.in. gauge (14.6 atm.) was the working fluid, and the tests covered the Reynolds number range from 20,000 to 200,000. Twist ratios, defined as the ratio of the tube length per 180 deg. twist to the tube diameter, were varied from 2.5 to 14. The effect of tube wall‐to‐gas temperature ratio was studied for values of up to 1.8 and the heat flux was varied from 104 to 105 B.t.u./hr. · sq.ft. (3 × 104 to 3 × 105 w./sq.m.).The results were compared with the results of previous heat transfer and pressure‐drop studies and were generally found to be in good agreement. An empirical correlation was developed for the heat transfer results that accounts for the effects of twist ratio, wall‐to‐gas temperature ratio, and tube length and includes most of the previous single‐phase results.
A study of the effects of internal rib and channel geometry in rectangular channels. Part II. Heat transfer
Authors: Buonopane Ralph A. , Troupe Ralph A. 
Published: June 2004

AbstractHeat transfer and pressure drop data were taken on commercial plate heat exchange equipment. Nusselt and Euler correlations were determined for each of the six commercial heat exchangers investigated. These correlations were combined to establish a single heat transfer‐pressure drop relationship for any plate type of heat exchanger channel.The results of this investigation were tested by using the correlations developed in Part I of this series to predict pressure drop data for the commercial unit based on their channel geometries. These predicted pressure drops were then used with the results of this part of the series to predict and compare heat transfer data.The correlations developed in this work allow one to determine the heat transfer characteristics in a ribbed rectangular channel from the pressure drop characteristics of the channel in question.
Effect of liquid‐packing surface interaction on gas absorption and flooding in a packed column
Authors: Coughlin Robert W. 
Published: June 2004

AbstractGas absorption, pressure drop, liquid holdup, and loading behavior in a packed column have been investigated using packing materials almost geometrically identical but fabricated from three different materials (ceramics, Saran, and polyethylene). For the absorption of oxygen into sodium sulfite solution, observed values of the liquid‐side, composite, overall mass transfer coefficient, KLa, were about 25% larger for the ceramic packing than for the polymeric packings. It was also observed that liquid loading occurs more readily in the case of the polymeric packing materials and it appears that the usual type of correlation is inadequate for predicting loading when polymeric packings are employed. In the case of liquid operating holdup no differences were observed from packing to packing. These observations are discussed in terms of the nature of the interaction between liquid and packing surface and it is pointed out how these phenomena may be fundamentally different from those of previous investigations, which relied upon surface‐active agents added to the liquid.
Prediction of jet length in immiscible liquid systems
Authors: Meister Bernard J. , Scheele George F. 
Published: June 2004

AbstractThe stability theory is used to predict jet length from jet inception to disruption for injection of one Newtonian liquid into a second immiscible Newtonian liquid. Knowledge of the length is essential for predicting the size of drops formed from jets. At low velocities jet length is controlled by the amplification of symmetrical waves which travel at the interfacial velocity of the jet. At higher velocities an abrupt lengthening of the jet may occur as a result of drop merging, and the jet length is then controlled by the growth rate of sinuous waves which are strongly velocity dependent. Jet disruption results from a geometrical limitation on the maximum amplitude of the sinuous waves. Predictions show good quantitative agreement with experimental data for thirteen mutually saturated systems over a wide range of variables and qualitative agreement with limited experimental data on the effects of initial disturbance level and mass transfer.
Temperature profiles of molten flowing polymers in a heat exchanger
Authors: Forsyth T. H. , Murphy N. F. 
Published: June 2004

AbstractThe Graetz‐Nusselt problem for polymeric flow in a constant wall temperature tube was studied, using a temperature‐dependent power law rheological model and temperature dependent fluid properties. Theoretical results compare within 6% of experimental results. The fluid model predicts an experimentally observed temperature maxima at a reduced radius between 0.7 and 0.8 for cooling at low flow rates.
Some general equations for reverse osmosis process design
Authors: Ohya Haruhiko , Sourirajan S. 
Published: June 2004

AbstractA generalized approach to reverse osmosis process design is presented for solution‐membrane‐operating systems characterized by the dimensionless parameters γ, θ, and λ defined in terms of the pure water permeability constant A, solute transport parameter (DAM/Kδ), mass transfer coefficient k on the high pressure side of the membrane, and the properties of the solution. Analytical expressions are derived, in terms of dimensionless quantities, for the change of volume of solution, concentration of the bulk solution and that of the concentrated boundary solution on the high pressure side of the membrane, the change in the permeating velocity of solvent water through the membrane, solute separation, and the other related quantities, at any instance, as a function of concentration of the product solution on the atmospheric pressure side of the membrane, or time from the start of the operation for reverse osmosis systems specified by γ, θ, and λ. The equations are applicable to membranes for which (DAM/Kδ) is independent of solute concentration and feed flow rate, and for aqueous feed solutions whose molar density can be assumed constant and whose osmatic pressure is proportional to mole fraction. The equations are developed first for the case of batch‐by‐batch operation, and their applicability to the flow case is then indicated.
Laminar‐nonlaminar transition for non‐Newtonian flow in annuli
Authors: McEachern Donald W. 
Published: June 2004

AbstractExperimental results on the laminar‐nonlaminar transition of aqueous solutions of hydroxyethyl cellulose in axial, isothermal flow in annuli are presented. For each polymer solution the end of the laminar regime is observed to occur at different flow rates at different axial distances from the entrance of the test section. For some polymer solutions in nonlaminar motion, the pressure gradient is not constant over the length of the test section.These data on transition in annuli are compared with predictions made using Hanks' transition criterion where only viscous contributions are considered and where viscous effects are considered and elastic effects accounted for approximately. Predictions where both viscous and elastic properties of the fluids are considered are in fair agreement with experiments. Predictions using purely viscous theory are less accurate than the viscoelastic predictions.
Thermal instability of a horizontal layer of liquid with maximum density
Authors: Sun Zu‐Shung , Tien Chi , Yen Yin‐Chao 
Published: June 2004

AbstractAn investigation is carried out to determine the onset of convection of a horizontal layer of liquid subject to temperature of T1 and T2 at lower and upper surfaces, respectively. The liquid is assumed to possess a maximum density value at Tmax with Tmax between T1 and T2. The temperature‐density relationship within the temperature range |T1 — T2| can be expressed as ρ = ρmax [1 — γ1 (T — Tmax)2 — γ2 (T — Tmax)3].Both rigid‐rigid and rigid‐free surface conditions were considered. The critical Rayleigh number defined in Equations (20) and (24) is found to be dependent upon two parameters.Experimental observations on the onset of convection were made and compared with the theoretical results. The experimental work consists of the measurement of the melting rate of a block of ice with melting from both below and above. In all cases, excellent agreement between experimental and theoretical results were obtained.