bluuebunny/crossref_metadata_2025_split huggingface dataset:
The oxidation of aqueous ferrous sulphate by thiobacillus ferrooxidans
Authors: MacDonald D. G. , Clark R. H. 
Published: March 2009

AbstractThe iron oxidizing bacteria, Thiobacillus ferrooxidans, were grown in an aqueous ferrous sulphate solution in batch and continuous culture vessels and the dependency of the specific growth rate on ferrous sulphate concentration, temperature, and pH are shown. The effect of carbon dioxide concentration on cell growth is also considered.The phenomenon of wall‐growth is shown to be an important characteristic of the organism which must be considered in any batch or continuous culture experiments. The role that it may have in the biological leaching process is also indicated.
Prediction of heats of mixing by a group solution model with application to alkane/alcohol mixtures
Authors: Nguyen T. H. , Ratcliff G. A. 
Published: March 2009

AbstractGroup solution models of liquid mixtures have been used previously to predict excess free energies of non‐ideal systems. With increasing experimental data available on heats of mixing, the application of a similar model to excess enthalpies has been investigated. The model allows for both structural and group contributions to excess enthalpies. The former contribution is determined from experimental data on mixtures of alkanes. The group contribution has been determined at 25°C and 45°C for systems containing alkanes and alcohols. Predictions require no experimental data on the system in question, and are in good agreement with experiment. Limited extrapolation to other temperatures and group compositions should be satisfactory.
Single bubble formation at orifices submerged in viscous liquids
Authors: Swope Richard D. 
Published: March 2009

AbstractThis paper concerns the slow formation of gas bubbles at circular orifices submerged in liquids with viscosities ranging from 10 to 1000 poise. A mathematical model is developed for predicting the bubble lift‐off size as a function of, basically, Froude, Weber and Reynolds numbers; it is analytical and does not depend on semi‐empirical coefficients.To check the validity of this model, experiments involving various gas flow rates and orifice diameters were performed in several liquids. The model consistently underestimates the experimentally obtained bubble size; the error of estimate varies from 10 to 25%. For bubble formation in a regime between the constant flow and constant pressure regimes, both the chamber pressure and the flow rate into the bubble vary. Furthermore, the instantaneous gas flow rate into the bubble can be many times greater than the average flow rate in the piping far upstream of the orifice exit. The former flow rate is important in determining the forces acting on the bubble and a method is given for obtaining its average value.
An experimental investigation of primary and secondary velocity for turbulent flow in eccentric annuli
Authors: Tebo Paul V. , Clump Curtis W. 
Published: March 2009

AbstractVelocity profiles for the turbulent flow of air in annuli of high eccentricities were determined. Unusual isovel curvature suggestive of secondary flow was found, but hot‐wire measurements did not detect secondary flow within experimental accuracy. Evidence suggests that most of the observed isovel structure is due to developing flow and the remainder is a normal pattern of primary velocity. The use of irrelevant velocity correlations and not the assumption of negligible secondary flow is suggested as the reason for lack of agreement between recent flow hypotheses and measured velocities.
Non‐ideal flow parameters for viscous fluids flowing through stirred tanks
Authors: Moo‐Young M. , Chan K. W. 
Published: March 2009

AbstractResidence time distribution functions for the flow of viscous fluids (6‐100 poises) through mechanically stirred tanks have been evaluated experimentally for various flowrates and stirrer speeds in three tank sizes, in geometrically similar systems. The results have been examined in terms of a mixed model suggested by visual observations of flow patterns within the tanks. A mechanistic model consisting of a dual backmix region and deadspace in series with a plug‐flow region was found to be compatible with these results. It was also found that previously tested models for stirred‐tank systems can be represented by limiting cases of this more general model. Further, it is shown that the parameters of the model can be expressed in useful engineering correlations derivable from the operating variables. Preliminary results on the effects of non‐Newtonian flow on the validity of the model are also presented. Application of the model to chemical reactor design is illustrated for first‐order reaction kinetics.
Axial dispersion in a tubular flow vessel with bends
Authors: Park Chan Mo , Gomezplata Albert 
Published: March 2009

AbstractA two measurement points pulse techniqque was employed to determine axial dispersion coefficients in a 3/4 inch diameter pipe with four 90 degree bends located at 50 inch intervals. Water velocities corresponding to Reynold numbers of 3,800 to 11,500 were used. It was found that the effect of bends on the overall dispersion coefficient depends on the Reynolds number and a characteristic length.Two mathematical models of a reactor with bends are presented. One model assumed that the bend section is a perfectly mixed reactor with an equivalent length. The second assumed a fixed equivalent length for the bend section and a proportional relationship between the dispersion coefficients in the bend and the straight section.
A dynamic theory of mass transfer at a wavy interface
Authors: Rice Richard G. 
Published: March 2009

AbstractA new theory to predict mass transfer at an interface undergoing stationary oscillations is presented. The theory describes mass transfer when a slightly soluble gas is dissolving in a dynamic liquid interface. It is shown that mass transfer under these conditions is a function of the square of wave amplitude, and depends, in a complex way, on a characteristic Schmidt and Reynolds number. The latter quantities are defined in terms of the characteristic wave‐length and frequency of the system periodicity. In the limit of large Reynolds and Schmidt numbers, which characterize most real liquid‐gas systems, the theory takes a particularly simple form and shows that the ratio of the mass fluxes for dynamic to stagnant interfaces is independent of Schmidt number and depends only on the square of the amplitude‐wave length ratio and the square root of the Reynolds number. Using the Kapitsa hydrodynamic parameters, the mass transfer theory is compared with data from a wetted‐wall column.
Application de l'équation de Wilson à l'estimation des enthalpies de mélange
Authors: Duran J. L. , Kaliaguine S. 
Published: March 2009

AbstractOn montre que l'équation de Wilson peut représenter simultanément les enthalpies libres d'excès et les enthalpies de mélange des systèmes binaires totalement miscibles. Les coefficients, dépendant de la température, sont calculés à partir des données binaires et permettent un calcul simple et précis des enthalpies des mélanges à plusieurs composants.
Compressibilities of helium‐nitrogen mixtures
Authors: Mathews J. F. , Morey D. C. D. 
Published: March 2009

AbstractThe compressibility factors of nitrogen, helium and three mixtures were determined at 310.93, 338.71, 366.48, 394.26, 422.04, and 449.82°K. over a pressure range from 100–5000 psia. using a variable volume‐constant mass apparatus. Values of Z are tabulated versus the experimental values of pressure. Compressibility factors were correlated using the virial and Redlich‐Kwong equations of state.
A correlation for the solubility of hydrocarbons in water
Authors: Leinonen P. J. , Mackay D. , Phillips C. R. 
Published: March 2009

AbstractA correlation has been developed for the solubility of C4 to C10 hydrocarbons in water at 25°C and atmospheric pressure. The excess Gibbs free energy is correlated in terms of an effective molar volume which is related to the actual molar volume adjusted to include the effects of the degree of branching, the number of olefinic and acetylenic bonds and the number of aromatic and cycloalkane rings. The root mean square deviation between 59 correlated and experimental solubilities is 20%. The range of solubilities is from 0.052 to 5150 g hydrocarbon per 106 g water. The correlation provides a rational procedure for the estimation of solubility of other hydrocarbons.
A turbulent transport model with emphasis on heat transfer to liquid metals
Authors: Thomas Lindon C. 
Published: March 2009

AbstractAn analysis of the energy transport to eddies in transit from the turbulent core to the wall region coupled with the elementary surface renewal and penetration model is presented for the turbulent tube flow of liquid metals. Previous formulations of the various forms of the surface renewal and penetration model have been based on the assumption that eddies arrive at the surface with initial temperature T1 equal to the bulk stream temperature Tb. However, due to the significance of molecular transport during the flight of eddies from the turbulent core to the wall region, the employment of this assumption immediately restricts the model to the analysis of the mean heat flux for fluids other than liquid metals. In contrast, the present analysis gives rise to an expression for the mean Nusselt number for turbulent tube flow which is shown to be applicable to fluids with moderate values of the Prandtl number (Pr = 0.5 ‐ 5.0) as well as to the flow of liquid metals at high values of the Reynolds number.
An analysis of heat transfer during flow of an air/water mist across a heated cylinder
Authors: Finlay I. C. 
Published: March 2009

AbstractEquations are developed for predicting local heat‐transfer coefficients over the forward‐facing half of a cylinder during transverse, mist flow. At low approach velocities predicted values are found to be in good agreement with corresponding measured values. With increase in approach velocity, agreement is found to fall off owing largely to the onset of a severe splashing or bouncing action. This effect is examined, together with effects of evaporation and convection at the free surface of the liquid layer formed on the cylinder.
A selectivity method for modelling the kinetics of pentene‐2 hydrogenation
Authors: Rao M. S. , Hudgins R. R. , Reilly P. M. , Silveston P. L. 
Published: March 2009

AbstractA maximum likelihood ratio was used as a statistical criterion for discriminating among twenty‐two kinetic models posited to describe the hydrogenation of mixed pentenes (cis‐ and trans‐2‐pentenes) with a Raney nickel catalyst. Selectivity ratio, the ratio of reaction rates of two different species, was used and found to be a suitable extension of conventional techniques for identifying rate controlling steps owing in this case to its reproducibility. Selectivity ratio models were of the Langmuir‐Hinshelwood form.Hydrogenation was performed isothermally at 20°C in benzene at five constant pressures corresponding to partial pressures of hydrogen of 22.5, 42.3, 62.3, 112.3 and 122.1 psia.Discrimination was attempted at each pressure, but found acceptable only at the three intermediate pressures. At each of these pressures, a model of similar functional form was found to represent the selectivity data; however, this model appears to be empirical.The likelihood ratio approach appears to be a powerful one for discriminating among a large number of models even with only a moderate number (˜ 20) of experimental observations.
White's method of thermodynamic calculations applied to ammoxidation of propylene
Authors: Suryanarayana K. , Reddy P. J. , Murti P. S. 
Published: March 2009

AbstractA method of steepest descent first applied by White et al. to the calculation of complex chemical equilibrium was used in this article to compute the equilibrium composition of a mixture resulting in the ammoxidation of propylene. As many as twenty species are likely to be present, some in insignificant quantities. A FORTRAN II Program was written for an IBM 1620 computer and calculations were made varying the feed composition, temperature and pressure. The results were discussed and qualitatively compared with those of the plant practice reported in the literature. The agreement is reasonably good when the oxygenated compounds are excluded from consideration.
Fluid velocity profiles near the wall of liquid‐fluidized beds
Authors: Allen B. G. , Smith J. W. 
Published: March 2009

AbstractA direct, non‐disturbing flash photolysis dye technique has been used to measure liquid velocities in 2.465‐in. beds of 0.1248, 0.233 and 0.368‐in. diameter lucite spheres at porosities of 0.8 and 0.9. Aggregative fluidization, including layering, was observed in all beds, and increased in magnitude with the larger spheres. Distinct velocity maxima were found from 0.5 to 2 particle diameters from the wall and distinct minima at from 0.6 to 1.2 particle diameters for the more particulately fluidized beds. Variations in velocity greater than the mean were observed.Conservatively estimated wall shear stresses were 2 to 5 times times larger than in the open pipe.
The separation of micron‐size particles from air by diffusiophoresis
Authors: Meisen A. , Bobkowicz A. J. , Cooke N. E. , Farkas E. J. 
Published: March 2009

AbstractThe continuous separation of micron‐size particles from air by diffusiophoresis in a parallel plate collector was studied theoretically. Two models for the particle behavior were considered. Model I was based on the assumption that the particles adopt the local fluid velocity whereas the Schmitt‐Waldmann equation was used to determine the diffusiophoretic velocity in Model II. The latter also included thermophoretic and gravitational effects.The two models yielded similar results when diffusiophoresis was predominant. The theoretical results were also used in the sizing of an experimental particle collector. The collector, which operated under laminar flow conditions, was capable of removing the particles effectively and its performance conformed with the theoretical work.
Laminar film boiling on a porous vertical wall with uniform suction velocity
Authors: Krishnamurthy M. V. , Ramachandran A. 
Published: March 2009

AbstractLaminar free convection film boiling on a porous vertical wall with uniform suction or blowing is analysed using boundary layer theory. The solutions are obtained assuming suction or blowing to be a disturbance superposed on the isothermal, impermeable wall case. Using a parameter involving the suction or blowing velocity, universal functions are derived for various values of Prandtl Number and cp(Tw — Tsat)/hfgPr. These universal functions can be used to estimate the heat transfer rate in the presence of suction or blowing. As expected, suction increases the heat transfer rate while blowing decreases the heat‐transfer. Even small velocities of suction or blowing could significantly affect the heat transfer. It is also found that the effects of suction or blowing are more pronounced at lower wall superheats.
Heat and mass transfer in spouted beds ‐ A review
Authors: Epstein Norman , Mathur Kishan B. 
Published: March 2009

AbstractThe considerable literature on spouting which has accumulated since the inception of this fluid‐solid contacting technique fifteen years ago is critically reviewed with reference to heat and mass transfer. The relatively meagre basic data on both surface‐to‐bed and fluid‐to‐particle heat transfer, as well as particle‐to‐fluid mass transfer, are interpreted wherever possible, in the light of understanding gained from more exhaustive information available on the hydrodynamics of the system. Contradicitions are noted and in some cases reconciled. Conclusions are drawn as to the relative merits of various correlations.Design equations for heating or cooling of solids for both batch and continuous systems are formulated and a new theoretical model to describe wall‐to‐bed heat transfer is proposed.
Coupled transport of heat and mass in laminar tube flow
Authors: Chen T. S. , Scheffel G. A. , Huang L. M. 
Published: March 2009

AbstractAn analysis is performed of the mutually dependent heat and mass transfer for gas flow in a circular tube. Sublimation occurs at the inner surface of the wall, while the outer surface is thermally insulated from the external environment. The flow is assumed to be laminar and hydrodynamically fully developed. Mathematical expressions are derived and numerical results are given for bulk temperature and bulk mass fraction, wall temperature and wall mass fraction, wall heat and mass fluxes, local Nusselt number, temperature and mass fraction profiles, and length of the development region. Comparisons are made of the results based on a parabolic velocity profile with those based on a slug flow profile.
L'effet du molybdène sur l'oxydation partielle du méthane par l'oxygène‐pur
Authors: Blanchard L. P. , Yim Yoeun 
Published: March 2009

AbstractL'influence du molybdène sur l'oxydation partielle du méthane par l'oxygène pur a été étudiée pour trouver les conditions menant à sa conversion complète en gaz de synthèse, sans excès d'oxygène ni formation de gaz carbonique, de vapeur d'eau ou de dépǒts de carbone. La carburation du molybdène par le méthane et sa décarburation par l'oxygène expliqueraient que seuls deux produits, le monoxyde de carbone et l'hydrogène, sont trouvés dans les gaz de sortie. La composition de ces gaz à l'équilibre a été calculée à partir de données thermodynamiques pour les étapes retenues et ce, pour toutes les conditions prévues d'opération. Soixante essais ont ensuite été faits pour vérifier ces compositions, en variant la température de 1200 a 1900°K, le poids de molybdène de 0 à 5 grammes, le rapport méthane‐oxygène de 1.6 à 2.2 et la vitesse spatiale horaire de 50 à 250. Au‐delà de 1600°K, les mélanges stoéchiométriques de méthane et d'oxygène en présence de molybdène ne donnent, en général, que du monoxyde de carbone et de l'hydrogène dans le rapport 1 à 2. L'analyse, par diffraction des rayons‐X, de la phase solide renfermant le molybdène, démontre la présence de carbure de molybdène, ce qui confirme le rǒle intermédiaire assigné au molybdène dans l'oxydation partielle du méthane par l'oxygène pur.
Influence du molybdène sur la cinétique des réactions de conversion du méthane en présence de H2O et CO2
Authors: Vanderschuren J. , Kaliaguine S. 
Published: March 2009

AbstractUne étude expérimentale de l'action catalytique du molybdène sur les réactions de conversion du méthane en gaz de synthèse par la vapeur d'eau et le gaz carbonique a été faite dans un réacteur différentiel à lit fluidisé.Les essais ont été réalisés de façon à limiter les réactions homogènes susceptibles de masquer l'effet catalytique.On montre l'importance de l'influence du rapport O2/CH4 de l'alimentation et des réactions hétérogènes d'oxydation du métal ou de formation du carbure Mo2C, sur les rendements.A partir des résultats cinétiques obtenus en présence du carbure et du métal pur, on propose un mécanisme réactionnel, et on présente une équation de vitesse pour la réaction de conversion du méthane par la vapeur d'eau sur le molybdène.
Improved parametric characterization of flow geometries
Authors: Kozicki William , Tiu Carlos 
Published: March 2009

AbstractAn improved parametric method is presented for characterization of the flow geometry in the rectilinear flow of non‐Newtonian fluids in open and closed conduits of arbitrary crosssection and in purely viscous, inelastic flow of non‐Newtonian fluids through packed beds and porous media. In the new formulation, an infinite number of geometric parameters characterize the flow geometry. The actual number required in a particular application is shown to be determined by the fluid model equation representing the rheological behavior of the fluid. For Ostwald‐de‐Waele and Ellis fluids with flow behavior indices s = 1/n and α integers, the number of geometric parameters required to represent the relationship between flow rate and pressure drop is given by s + 1 and α + 1, respectively. The efficacy of the present method is demonstrated by comparisons with available results for various fluid models and flow geometries.
Experimental heat capacities of carbon dioxide‐methane mixtures at elevated pressures
Authors: Bishnoi P. R. , Robinson D. B. 
Published: March 2009

AbstractThe heat exchanger method of determining the ratio of heat capacity at a pressure to the heat capacity at a low pressure was used to obtain data on two binary mixtures of methane and carbon dioxide containing 14.49 and 42.30 mole % methane. The data were obtained at pressures up to 2,250 psi in the temperature range of ambient to 150°C and are expected to be accurate within ± 0.5 % in the regions removed from the pressure maxima and within ± 1 % in regions close to the maxima. Heat capacities of the two binary mixtures were calculated using the BWR equation of state, the generalized correlations of Curl and Pitzer and Yen and Alexander, and the method of Orentlicher and Prausnitz. The calculated values were compared with the experimental values.
Temperature coefficient of gas solubility for regular solutions
Authors: Hayduk W. , Buckley W. D. 
Published: March 2009

AbstractA semi‐empirical method is reported for predicting the temperature coefficient of gas solubility for regular solutions. It appears to be capable of describing the temperature coefficient to an accuracy approaching that of the solubility measurements themselves. The method requires a knowledge of the solvent solubility parameter and critical temperature, as well as at least one solubility (at any temperature) of the gas in the particular solvent. New data for the solubilities of methane in hexane, heptane, octane, dodecane and hexadecane, over the temperature range (where possible) from O°C to 75°C along with a large number of previously published data are used to show the effectiveness of the proposed method.
Trays for gas‐liquid contacting
Authors: Kilgallon J. D. , Furter W. F. 
Published: March 2009

AbstractA type of tray for gas‐liquid contacting is described, in which the free area for gas flow through the tray is variable with and controlled by the gas flowrate. The property through which control of the free area is effected is the surface tension of the liquid phase. The advantages are the same as those of ballast and valve trays; namely, reduced pressure drop at high gas rates resulting in increased column capacity, and reduced free space at lower gas rates resulting in high mass transfer efficiency at low and medium vapor loadings as well. Tooling and production costs for the trays of the present investigation, however, are considerably lower than for ballast or valve trays or any other types which require machining operations in their fabrication, and are as low or lower than for sieve trays. Initial experimental comparisons with conventional trays demonstrated that the trays of the present investigation, although designed primarily for operation at high vapor loadings, were indeed capable of yielding high mass transfer efficiencies in the low‐to‐medium range of vapor loading
Heats of mixing for homologous series of ketones and their prediction from group interaction theory and the congruence principle
Authors: Ramalho R. S. , Tillie J. L. , Kaliaguine S. 
Published: March 2009

AbstractHeats of mixing for 12 binary systems of ketones at several temperatures are reported. Application of an extension of the congruence principle and the group interaction theory is studied, for these data. A graphical procedure for prediction of heats of mixing data is proposed