bluuebunny/crossref_metadata_2025_split huggingface dataset:
A concentrated suspension model for the couette rheology of blood
Authors: Brennen Christopher 
Published: March 2009

AbstractA simple “cell” method for concentrated suspensions has been used to construct a model for the rheological behavioi of blood. The model includes the physical pioperties of the suspending medium, red cell membrane and red cell fluid content. Predictions of the gross viscosity of red cell suspensions are found to agree very well with experiment in the cases of hardened red cells (or normal red cells at very low shear rate) and of normal red cells in the asyniptotic limit of high shear rates. The behavior at intermediate shear rates requires a knowledge of the visco‐plastic properties of the membrane and a number of membrane models are investigated. Of particular interest is a plastic membrane which employs a membrane yield stress obtained from other experiments and whose results are qualitatively in agreement with the viscometric data at these intermediate shear rates.
Phase holdup characteristics of three phase fluidized beds
Authors: Kim S. D. , Baker C. G. I. , Bergougnou M. A. 
Published: March 2009

AbstractThe individual phase holdups in two (liquid‐air, liquid‐solids) and three (liquid‐air‐solids) phase fluidized beds have been measured over a wide range of liquid and gas velocities. Ex‐periments were canied out in a large two‐dimensional bed. Three solids were used ranging in size from 1 to 6 mm.The effect of viscosity (1‐70 cp) was determined using solutions of sugar and carboxymethyl cellulose of different concentrations. Various acetone‐water mixtures were employed to examine the effect of surface tension in the range 40‐73 dyne/cm.Beds of particles having a minimum fluidizing velocity in the liquid of less than 1.28 cm/sec were found to initially contract upon the injection of gas. In contrast, beds of particles having minimum fluidizing velocities exceeding tins value were found to expand.
Three dimensional turbulent wall jets
Authors: Narain Jai Prakash 
Published: March 2009

AbstractJets issuing tangentially to an impermeable flat surface from orifices of finite aspect ratio are termed three‐dimensional wall jets. The turbulent flow of viscous incompressible fluid associated with such wall jets has been investigated analytically. Results are presented for the wall jets issuing from orifices of various shapes and several aspect ratios. The maximum velocity shows three regions of decay. The potential core region is followed by a characteristic decay region where maximum velocity decays in a manner dependent on the shape and aspect ratio of the orifice. Following this region, there is a radial wall jet type maximum velocity decay region. All three‐dimensional wall jets issuing from any arbitrary cross‐sectional orifice decay in a similar manner in this radial decay region. The half‐velocity width grows faster in the transverse direction than in a direction normal to the flat surface. The analytical results agree reasonably well with existing experimental results.
Activation de la tourbe de sphaigne par le dioxyde de carbone et agglomération du charbon actif produit
Authors: Son P. N. , Khanh P. V. , Chornet E. 
Published: March 2009

AbstractThe physical activation of peat moss using CO2 has been investigated with respect to the operational variables and the characteristics of the active carbon produced. Peat coke is produced during carbonisation with a 30% yield. The activated carbon accounts for 25% of the initial air dried peat moss.Analysis of the active carbon has revealed a surface area up to 600 m2/g and a chemical reactivity similar to commercial active carbon as measured by the iodine, phenazone and phenol indexes.The active carbon thus produced is a powdered material, with a weak abrasive resistance. Agglomeration of the carbon and subsequent pelletization has been done with ammonium ligno‐sulfonate, water, and the application of pressure. Resistant pellets can be obtained using 15‐20% lignosulfonate and 3000 psi.
Modified van der waals equation for the dense gaseous and liquid regions from PVT data for methane
Authors: Dingrani J. G. , Thodos George 
Published: March 2009

AbstractPVT measurements available in the literature for methane in the gaseous and liquid regions were used with the van der Waals equation of state,

to obtain values of the internal pressure parameter, a, where the covolume parameter was taken as b = vc/3. The conditions covered temperatures from 114.53°K (TR = 0.599) to 611°K (TR = 3.20) and pressures up to 3000 atm (PR = 65.50). A dimensionless relationship was developed for the dependence of the parameter a on density and temperature for the gaseous and liquid regions. Density values for methane were calculated from the resulting equation and were compared with the corresponding experimental values to produce an average deviation of 0.26% (791 points). This relationship also enabled the accurate prediction of density values for substances having similar critical compressibility factors as methane (zc = 0.289). For neon and ammonia, this relationship was found to have a limited applicability.
Evaluation of capital cost data: Drives
Authors: Woods Donald R. , Anderson Susan J. 
Published: March 2009

AbstractCapital cost correlations are given for electric and gasoline motors, steam, gas and combustion‐gas driven turbines, power transmission units and power converters. Correlations available in the literature and current data are compared on a consistent basis. Thirty‐eight graphs show the relative magnitudes of the different correlations and the recommended correlation for each type of equipment is summarized in a table.
The capillary break‐up of a binary liquid column inside a tube
Authors: Mikami T. , Mason S. G. 
Published: March 2009

AbstractThe break‐up of a stationary viscous liquid cylinder surrounded by an immiscible viscous liquid contained in a circular tube by capillary forces at the fluid interface is considered.It was found that the maximum growth‐rate parameter f* depends upon η'/η, the ratio of the viscosity of the inner liquid to that of the outer liquid and a/S, the ratio of the radius of the inner liquid cylinder to that of the tube. Both f* and corresponding wavelength parameter (2πa/λ)* have been calculated theoretically; measured values of both parameters are in good agreement with the theory.
Comparison of methods for the prediction of liquid holdup for upward gas‐liquid flow in inclined pipes
Authors: Gregory G. A. 
Published: March 2009

AbstractThree methods for predicting the in situ liquid volume fraction for the upward flow of gas‐liquid mixtures in inclined pipes have been tested against available data from the literature. Combined with the results of an earlier paper, a total of seven methods have been compared.It is demonstrated that for angles of up to 10°, pipeline inclination has little effect on the predicted holdup. Correlations arc recommended for use under specified conditions.
A filtration method for measuring particle interactions in latexes
Authors: Homola A. M. , Robertson A. A. 
Published: March 2009

AbstractThe repulsion forces between latex particles determine the stability of the latex. These may be estimated by determining, by a filtration method, the minimum pressure required to initiate coagulation. This minimum filtration pressure, when corrected for the resistance of the filter, was found to be independent of the pore size of the filter and of the amount and concentration of the latex. Experiments were conducted with both film‐forming (styrene‐butadiene) and non‐film forming (styrene) latexes.The method provides a simple and convenient means of assessing the colloid stability of suspensions of larger particles. With model, monodisperse latexes the method permits the comparison of measured interparticle forces with those predicted by theory. The minimum coagulation pressure and the electrophoretic mobility curves correlate well when plotted against pH or electrolyte concentration. A maximum in the minimum coagulation pressure curve occurs at 10−3 M NaCl. The critical pressure increases with an increase in the concentration of nonionic surfactant (C18E50) while the mobility decreases.
Viscous dissipation effects on turbulent heat transfer in pipes with uniform wall heat flux
Authors: Ou Jenn‐Wuu , Cheng K. C. 
Published: March 2009

AbstractAn analysis is made of the turbulent Graetz problem with viscous energy dissipation effects in pipes with uniform wall beat flux. The effects of viscous dissipation on fully developed Nusselt numbers are studied for fluids with Prandtl numbers 1, 10, 102, 103 for Reynolds numbers between 5 × 103 and 5 × 105 with both cooling and heating conditions at the pipe wall. The viscous dissipation effects on convective turbulent heat transfer in arctic hot oil pipelines are discussed.
The dispersed flow model for a biological reactor as applied to the activated sludge process
Authors: Turian Raffi M. , Fox George E. , Rice Philip A. 
Published: March 2009

AbstractA theoretical analysis of a dispersed flow biological reactor is presented in which Monod growth kinetics are used to describe the substrate utilization rate and the bacterial growth rate. Different bacterial and substrate dispersion coefficients are taken into account. Approximate perturbation solutions are established for two limiting situations, when the inverse Peclet number ϵ is very small and when it is very large. In the former case the perturbation analysis is singular. These perturbation solutions are compared with the solutions of the numerically integrated equations over a range of parameters corresponding to actual activated sludge systems. The application to the activated sludge system is discussed.
Mass transfer in venturi scrubbers
Authors: Virkar P. D. , Sharma M. M. 
Published: March 2009

AbstractThe theory of gas absorption with chemical reaction was used to obtain values of effective interfacial area, a, liquid‐side mass‐transfer coefficient, kLa, and gas‐side mass transfer coefficient, kGa, in a venturi scrubber for the Wet‐Approach mode of operation. Some data were also obtained for the Pease‐Anthony mode of operation in order to make a rational comparison between the two modes of operation. The hydrodynamic characteristics of the venturi scrubber were studied for the two modes of operation over a wide range of gas and liquid flow rates. Further, the effect of the viscosity of the liquid and the surface tension on effective interfacial area was investigated.
A model for the formation of calcium carbide in solid pellets
Authors: Brookes C. , Gall C. E. , Hudgins R. R. 
Published: March 2009

AbstractExperiments have been conducted on the formation of calcium carbide in the solid state from 2.22‐cm diameter cylindrical pellets of a 3/1 mole mixture of carbon and lime between 1650°C and 1720°C at 50 mm Hg CO pressure.The reaction was modelled assuming that heat transfer across a growing product layer controls the rate of movement of a reaction front where the overall reaction to form CaC2 is assumed to occur instantaneously to a fractional conversion f. The model depends upon a knowledge of the CaC2 decomposition rate in the product layer ko2e−ΔE/RgT and the effective thermal conductivity k0. These may be estimated from independent data but require adjustment for particular pellet conditions. Good agreement with the data shows that the model is adequate for preliminary design and optimization studies.
Semi‐empirical formulae for the prediction of diffusion in liquid systems
Authors: Simons J. , Ponter A. B. 
Published: March 2009

AbstractA critical survey of the published theoretical and experimental approaches to diffusion in liquids is presented. A study of the effects of temperature and viscosity demonstrates that the Stokes — Einstein equation and other relations derived from the hydrodynamic theory can only be applied in special cases. Correlations based on Eyring's absolute rate theory are shown to predict diffusivities more accurately in most cases at the expense of additional complications some of which are shown to be unnecessary.
Induced liquid phase mixing due to bubble motion at low gas velocity
Authors: Subramanian Gopal , Tien Chi 
Published: March 2009

AbstractLiquid phase mixing induced by gas bubbles at low gas velocities was studied experimentally. An experimental technique based on the principle of spectrophotometry was developed and applied in the experimental work. Experimental evidence suggests that the mixing phenomenon can be described as a diffusive process characterized by an effective diffusivity which is found to be a linear function of superficial gas velocity.
Flow analysis and end corrections in falling coaxial cylinder viscometry
Authors: Chee K. K. , Rudin Alfred 
Published: March 2009

AbstractThe assumptions involved in the analysis of flow of polymer melts in a closed end falling coaxial cylinder viscometer(1–3) are examined and it is shown that true values of shear rate and shear stress at the wall of the moving cylinder can be obtained by assuming classical Poiseuille flow. Flow curves obtained with a variety of apparatus geometries, driving loads and polymers are consistent with those of other measurement techniques. This apparatus, which is a simple modification of a capillary extrusion rheometer, provides measurements of apparent viscosity at much lower shear rates than can be obtained with the former viscometers.A quantitative measurement of end correction effects is provided by the present analysis. End effects, which are formally similar to those in capillary extrusion, were measured for several polystyrenes and polyethylenes.
Mixing of viscoelastic fluids with helical‐ribbon agitators. I — Mixing time and flow patterns
Authors: Carreau P. J. , Patterson I. , Yap C. Y. 
Published: March 2009

AbstractBatch mixing of viscous fluids with helical‐ribbon agitators in 2.4 liter and 13 liter vessels has been studied for agitator speeds up to 200 RPM. Seven different agitators of different dimensions were employed in this work. Mixing times were measured using a decoloration technique and circulation times were determined by the tracer bead method. In addition, velocity profiles were obtained from streak photographs using selective illumination of the vessel and PVC powder as tracer particles.It was found that the mixing times of Newtonian fluids, which agreed with previously published data, were considerably (3 to 7 times) shorter than those of the viscoelastic fluids. The mixing time was strongly affected by the fluids' elasticity; increasing as the fluid elasticity increased. The velocity profiles were qualitatively similar for all the fluids but showed decreased axial circulation and increased circumferential flow as fluid elasticity increased. However, mixing is not only a function of the axial circulation (impeller pumping rate) but also is a function of the perturbations superimposed on the main flow. A simple, first approximation model based on the impeller geometry and flow patterns is proposed to correlate the circulation capacity and mixing time data for the various geometries studied.
A least squares approach to model reduction and the design of low‐order controllers
Authors: Wilson Robert G. , Seborg Dale E. , Fisher D. Grant 
Published: March 2009

AbstractState space process models and feedback control laws are simplified by eliminating selected state variables using a modified least squares technique. The revised technique uses random perturbations to excite the high order system and the resulting reduced‐order models tend to be more robust than those derived using conventional least squares and deterministic inputs. Low‐order controllers were designed for a pilot scale, double effect evaporator using the modified least squares approach. These controllers performed well in both experimental and simulated response tests.
The flow of sand/water slurries in horizontal pipes with internal spiral ribs — effect of rib height
Authors: Singh V. P. , Charles M. E. 
Published: March 2009

AbstractThe effect of secondary flows created by an internal spiral rib in an otherwise conventional smooth 2‐inch pipe on the transportability of “settling” suspensions of sand in water was investigated with emphasis on the effect of rib height.While the ribs were found to be a disadvantage at relatively high average mixture velocities because of increased pressure gradients, they were advantageous at low velocities. The deposit velocity and the pressure gradient at the deposit velocity in ribbed pipes of several pitch to diameter ratios and rib heights were correlated with respect to the corresponding smooth pipe values. These correlations are useful in pipeline design. The optimum rib geometry was estimated to be a pitch to diameter ratio of about 8 and a rib height in the range of 10–15% of the pipe diameter for the solid‐liquid mixtures investigated.
Wall mass transfer in vertical and horizontal slurry pipelines
Authors: Postlethwaite John , Holdner D. N. 
Published: March 2009

AbstractWall mass transfer rates of dissolved oxygen have been measured in a vertical pipe, 5 cm. I.D., carrying aqueous slurries of 5, 10, and 15 vol%, 60–100 and 30–50 mesh sands at velocities in the range 1.2 to 3.35 m/s. The results show increases of up to 100% over those found with water, with the effect of the solids increasing with decreasing particle size and increasing with increasing concentration. The jD factors decreased linearly with increasing Res, unlike the previous results with horizontal pipes where maxima were found relating to vertical concentration gradients.
The effect of temperature on coalescence of liquid drops at liquid/liquid interfaces
Authors: Vijayan S. , Furrer M. , Ponter A. B. 
Published: March 2009

AbstractDrop/interface coalescence times measured at 293–343K are reported for three oil/water systems (benzene, paraffin oil and 1,1,2,2‐tetrabromoethane) with different interface ages. The anomalous coalescence behavior of water droplets is explained by considering the static electrical double‐layer residing at the interface which influences the film thinning and the film rupture processes.Analyses using simplified coalescence models reveal that the incorporation of temperature dependence on the physical properties such as density difference between phases, viscosity of the continuous medium and interfacial tension, does not produce satisfactory agreement with the measured coalescence times.The effect of mutual saturation in contrast to unsaturated systems on coalescence times is illustrated. The reproducibility of the drop/interface coalescence times is examined and explanations are offered, relating the method and the conditions of the experimentation.Finally the importance of both the coalescence time and the film thickness to drop stability analysis is demonstrated.
Characterization of the evaporation rates of complex hydrocarbon mixtures under environmental conditions
Authors: Goodwin S. R. , Mackay D. , Shiu W. Y. 
Published: March 2009

AbstractThe characterization of the evaporation rate of complex hydrocarbon mixtures, such as commercial oil fractions, under environmental conditions is discussed. It is shown that the relevant thermodynamic quantity is the total volume of vapour (per unit of initial oil mass) removed under isothermal differential distillation conditions (V m3/kg) as a function of the mass fraction of the oil remaining (F). Plots of F versus V for various isothermal conditions can be used to estimate evaporation rates since it is shown that V is equivalent to the group KsAsτs/Ms where Ks is the evaporation mass transfer coefficient (m/s), As is the spill area (m2), τs is the evaporation time (s) and Ms is the spill mass (kg). The basis of a methodology for estimating environmental evaporation rates is thus outlined. Methods of obtaining V versus F data are discussed, with calibrated wind tunnel evaporations being preferred. The estimation of evaporation rates under spreading and non‐isothermal conditions and the analogous dissolution process are discussed briefly.
Holographic determination of mass transfer due to impinging square jet
Authors: Masliyah Jacob H. , Nguyen Trung T. 
Published: March 2009

AbstractLocal mass transfer from a flat plate under the influence of an impinging laminar air jet, issuing from a square tube, has been studied using laser holographic interferometry. No angular variation in mass transfer was found to exist near the jet centre. However, in regions far from the jet centre a periodic angular variation in mass transfer was shown to exist. Regression equations for the local mass transfer coefficient are presented for Re = 710, 980, 1325 and 1810.
The electroreduction of oxygen to hydrogen peroxide on fixed bed cathodes
Authors: Oloman C. , Watkinson A. P. 
Published: March 2009

AbstractThe production of dilute alkaline peroxide bleaching solutions by electro‐reduction of oxygen on fixed beds of graphite particles was investigated. The cell was operated both in the two‐phase mode where oxygen saturated 0.1 M NaOH was passed continuously through the bed, and in the three‐phase mode where oxygen gas and electrolyte flowed co‐currently downward through the cell. Experiments were carried out under oxygen pressures from 1 to 12 atmospheres. The peroxide concentration at the reactor outlet, and the current efficiency dependence on the applied current are reported as functions of electrolyte and oxygen flowrates, oxygen pressure, graphite particle size, fixed bed height and electrolyte pH. Conditions for producing maximum peroxide concentrations are described and possible rate limiting steps in the reaction suggested.
Droplet size distribution: An improved method for fitting experimental data
Authors: Lekic A. , Bajramovic R. , Ford J. D. 
Published: March 2009

AbstractThe problem of obtaining the best fit for experimentally determined droplet size distributions is critically examined. Previous analyses have been restricted to linear representations of droplet distribution information. By using a statistical distribution and least squares fitting for non‐linear systems, the least squares estimates for parameters are obtained. The upper limit function and Chi‐square distribution are found to give good approximations for drop size distribution. Very precise fits of experimental data from a number of authors are obtained, the normalized volume distribution being more precisely approximated than the normalized number distribution.
Modified parameters for the Redlich‐Kwong equation of state
Authors: Kato Masahiro , Chung W. K. , C.‐Y.Lu Benjamin 
Published: March 2009

AbstractTwo new parameters are proposed for the Redlich‐Kwong equation of state. They are developed for pure components at T>Tc with emphasis placed on the application of the Redlich‐Kwong equation to vapor‐liquid equilibrium studies.The proposed parameters reflect the departure from the experimental Tc and Pc values, and are related to the conventional parameters. Calculated critical isotherms of pure propane and hydrogen by means of the proposed method and two methods available in the literature are compared and discussed.A set of mixing rules is proposed for correlating vapor‐liquid equilibrium data. Critical volumes and acentric factors of pure components are not required in the application of these mixing rules.Applicability of the proposed new parameters and mixing rules is demonstrated by the correlation of vapor‐liquid equilibrium data for five binary systems at thirty‐two isothermal conditions and by the prediction of the triple‐values dew‐point curve for the methane‐n‐butane mixtures.Based on a paper presented at the Research Seminar on “Vapor‐Liquid Equilibria in Multicomponent Mixtures” November 2–6, 1975 at Jablonna, Poland.