bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaporation rates in spray drying
Authors: Dlouhy J. , Gauvin W. H. 
Published: February 2011

AbstractHeat and mass transfer coefficients have been determined during the evaporation of water sprays produced by pneumatic atomizing nozzles in a vertical, cocurrent spray dryer, 8‐in. in diameter and 14 ft. high, under various operating conditions. The progressive evaporation of the spray down the chamber was followed by taking samples of the drying air and of the water droplets at various distances from the nozzle, and a new volumetric method for the accurate determination of air humidities was developed.For droplet spray ranging in mean diameter from 11.5 to 38.5 microns, the heat and mass transfer coefficients were found to be essentially the same as for single, stationary droplets evaporating in still air, the similarity being attributed to the almost equal diffusivity of the drop and of the air stream, resulting in negligible relative velocity. Certain important aspects of spray dryer design are discussed, and a method is outlined for the calculation of the residence time in the evaporation zone.
Pressure drop of single phase flow through raschig ring type tower packings: Effect of hole size
Authors: Fan Liang‐Tseng 
Published: February 2011

AbstractThe effects of hole size of the cylindrical tower packing on pressure drop of single phase flow were investigated. It was shown that the hole size had a profound effect on the correlation of pressure drop data. This was attributed to the difference in the characteristics of the spaces inside and outside the packing units and to the interlocking of the packing units in the beds.
Fundamental aspects of solids‐gas flow: Part IV: The effects of particle rotation, roughness and shape
Authors: Torobin L. B. , Gauvin W. H. 
Published: February 2011

AbstractThis paper examines the various complicating effects which rotation, surface roughness and shape impose on the motion and drag of single particles entrained in a fluid. In general, rotation appears to have little effect on the drag coefficient at low Reynolds Numbers, but influences the linearity of the motion and may thus play a part in the mechanism of particle entrainment in conveyed solids‐gas systems. Negative lift has been observed in the critical Reynolds Number region as the result of asymmetry in the wake structure. Surface roughness will cause an early transition to a turbulent boundary layer at higher Re values, which will result in an appreciable decrease in drag coefficient, but it may increase the drag at low Reynolds Numbers.The effect of particle shape is more complex than has been suggested by previously published analyses. The available empirical correlations are discussed and compared, and indicate a dependency on the particle‐to‐fluid density ratio.
The corrosion behavior of aluminum in natural waters
Authors: Godard Hugh P. 
Published: February 2011

AbstractThis paper reviews the behavior of aluminum in contact with natural waters. The influence of water composition and service factors on corrosivity to aluminum are discussed. Laboratory pitting test methods are described and data are presented to support the existence of a cube root (in time) rate curve for the pitting of aluminum in water. Information on the pitting of aluminum in 17 Canadian waters is given and mention is also made of the pitting of aluminum in seawater and oil field brines. A statistical treatment of pitting data is presented. Finally, measures for extending the life of aluminum equipment subject to pitting by water are suggested.
Fundamental aspects of solids‐gas flow: Part V: The effects of fluid turbulence on the particle drag coefficient
Authors: Torobin L. B. , Gauvin W. H. 
Published: February 2011

AbstractThis article presents an analysis of the experimental evidence presently available on the effects of the free‐stream turbulence on particulate momentum transfer, obtained from both wind‐tunnel tests with stationary bodies and from single‐particle systems in which the solid is moving freely with the stream. Original experimental measurements recently obtained with a radio‐tracer technique are also included. The drag coefficient appears to depend primarily on the magnitude of the relative turbulence intensity and on the particle Reynolds Number, while acceleration has negligible effects. Increasing intensities cause a systematic regression of the transition region of the drag coefficient curve towards lower Reynolds Numbers, together with a moderate increase of the drag coefficients for both the subcritical and supercritical Reynolds Numbers. The momentum transfer behavior suggests the occurrence of a laminar‐turbulent transition in the attached boundary layer at a critical value of the Reynolds Number for a given relative intensity. Indirect evidence involving heat and mass transfer phenomena appears to support this hypothesis.
Design of steam tracing systems for protection against freezing
Authors: Cotton W. S. 
Published: February 2011

AbstractProcess or service pipe lines containing materials which freeze readily must be protected during shutdown periods in cold weather. The desired temperature may be maintained in the pipe by installing a steam‐heated tube under the pipe, and enclosing both the pipe and tracer tube with the insulation. A rational thermal design method has been developed which permits the estimation of the heating requirements. The method may also be applied to tracers containing other heating media.
Optimal bypass rates for sequences of stirred tank reactors
Authors: Aris Rutherford 
Published: February 2011

AbstractA general method of finding the optimal volumes, temperatures and bypass rates for a sequence of stirred tank reactors is developed. After a discussion of the method of dynamic programming, the example of a sequence of adiabatic reactors of equal volume with a single reaction is used as an illustration. A simple graphical construction for determining the optimal bypass rates is given for this case. The limiting cases of the optimal control of a batch reaction by addition of cold feed is also solved.
The effect of intraparticle temperature distribution on the catalytic effectiveness factor of a porous catalyst
Authors: Akehata T. , Namkoong S. , Kubota H. , Shindo M. 
Published: February 2011

AbstractThe effect of intraparticle temperature distribution on the catalytic effectiveness factor is derived, and its magnitude is estimated using an approximate solution. These calculations show that for the several cases examined the term containing the effect of temperature is less than 10% of that due to the concentration effect.
Taylor diffusion in tubular reactors
Authors: Coste Joseph , Rudd Dale , Amundson Neal R. 
Published: February 2011

AbstractIn order to estimate the effect of velocity profile and radial diffusion on conversion in tubular reactors the assumption of Taylor diffusion is adopted. This leads to equations which are simple, but because of the numerical instability of these equations they are approximated to by a cell model in order to obtain numerical results. It is shown that the cell model can be a very good approximation to the one dimensional diffusion equation. If the Taylor diffusion model is valid for systems involving chemical reaction and heat transfer it may be concluded that while there seem to be no gross effects in a tubular turbulent reactor there are differences in detail, such as maximum temperature at the hot spot, which may be important.
Optimum performance of combined flow reactors under adiabatic conditions
Authors: Cholette A. , Blanchet J. 
Published: February 2011

AbstractIrreversible first‐ and second‐order reactions are studied for combinations of tubular and CST reactors when endothermal or exothermal adiabatic conditions prevail.Typical results presented for MT and TM models show the variation of either the conversion or the relative residence time as a function of the mixing level of the system.A graphical method, applicable generally to MT reactors, provides a simplification over that of successive approximations required for model TM.For the conditions investigated broad limits are indicated of the optimum reactor combinations.
The hydraulic characteristics of two‐phase co‐current flow through glass fibres
Authors: Gunn D. J. , Aitken A. R. 
Published: February 2011

AbstractThe mechanism of flow of air and water through packed glass fibres has been studied. Pressure drops and liquid hold ups were measured as a function of gas and liquid flow rates and the packing characteristics. It has been found that the pressure difference measured is dependent upon the history of previous gas and liquid flow rates in the bed. The liquid hold up is defined entirely by the gas and liquid flow rates. An analysis of the flow mechanism shows that the capillary forces interact with the fluid pressures in the bed. For example an increase in gas flow rate followed by a reduction to the same flow rate has been shown to reduce the resistance of the bed to gas flow even though the liquid flow rate is unchanged. A measure of the irreversibility of the flow operation is suggested.
The relation between the Margules and van Laar equations: The square‐root equation
Authors: Otterstedt J.‐E. A. , Missen R. W. 
Published: February 2011

AbstractThe excess free energy of mixing (ΔGE) has been used to show that the Margules and van Laar equations are reciprocally related. Thus if the Margules equation is written as χG = ΔGE/x1x2 = Σakx1k, then the van Laar equation can be written as χG−1 = Σbkx1k. It is known from previous work that the Margules equation does not adequately represent the thermodynamic properties of solutions of alcohols in non‐polar solvents over the whole range of composition, and it is pointed out that the van Laar equation cannot be used if the excess function changes sign. In such cases the use of a square‐root analogue of the Margules equation, χG = Σckx1(k‐2)/2, is proposed. This equation satisfactorily accounts for the rapid increase in χ as the mole fraction of alcohol becomes small and is empirically useful. However, it has theoretical disadvantages; it cannot be used to determine by extrapolation the value of the partial molar excess thermodynamic property for component 1 in an infinitely dilute solution; furthermore, it predicts a violation of the second law in the case of free energy of mixing for solutions dilute in component 1, but the region of violation lies outside the experimental range for x1 as low as 0.01.
A review of mass transfer to interfaces
Authors: Harriott Peter 
Published: February 2011

AbstractThe theories for mass transfer to rigid or mobile interfaces are reviewed and compared with selected experimental data. Except for transfer to particles in stagnant fluids, there is no case where the rate depends on the first power of the diffusivity, as implied by the film theory. The transfer coefficients for single rigid spheres, for particles in packed beds, and for the gas film in packed absorbers vary with about the 2/3 power of the diffusivity, as predicted by the boundary layer theory, which works fairly well for these cases because transfer to the wake region is relatively small. The penetration theory holds exactly for many devices which expose liquid surfaces for a short and known contact time, and, judged by a 0.5 exponent for the diffusivity, the penetration theory probably holds for the liquid phase in absorbers and for both phases in bubble‐cap towers. Theory and data for transfer to mobile interfaces show the coefficients to vary with D0.5 to D3/5, the limiting solutions for high and low interface velocity corresponding to the penetration theory and the boundary layer theory. Mass transfer in turbulent fluids is an unsteady‐state process, and the transfer coefficient varies with the 0.5‐0.8 power of the diffusivity even with very high turbulence.
The reduction of pressure gradients in oil pipelines by the addition of water: Numerical analysis of stratified flow
Authors: Charles M. E. , Redberger P. J. 
Published: February 2011

AbstractThe addition of water to crude oil pipelines appears to be an important method for decreasing the pressure gradient for a given oil throughput. Although the concentric oil‐in‐water flow pattern provides the greatest possible reduction, the general case, in which the liquids are stratified as a result of the oil and water having different densities, is also characterized by reductions in pressure gradient.To evaluate the magnitude of the pressure gradient reduction to be expected in stratified flow systems, the Navier‐Stokes equations were solved by a numerical procedure utilizing a digital computer, for the laminar stratified flow of two Newtonian liquids — oil and water — in a circular pipe. Liquid flow rates were obtained for the flow of five hypothetical oils ranging in viscosity from 4 to 1500 centipoises in the presence of water, by computing the oil and water velocity profiles for a series of arbitrary oil‐water interface positions. It was found that the maximum values for the pressure gradient reduction factor ranged from 1.12 to 1.31 for the five oils and occurred at water contents ranging from 12 to 93 per cent respectively.The computed reduction factors were considerably lower than experimental values and this appears to indicate that wave motion and mixing at the oil‐water interface produces a further and very significant reduction in the pressure gradient.
Simultaneous heat and mass transfer in a fluidized bed of drying silica gel
Authors: Heertjes P. M. 
Published: February 2011

AbstractThe determination of the partial coefficients of heat and mass transfer in air from and to a drying fluidized mass of silica gel is given. The analogy between the two methods of transport in the bed has been studied by an inspection of the relation between the two coefficients. A correlation of these coefficients with the void fraction, the superficial velocity, the particle size and the tube diameter of the bed has been derived. This correlation has been transformed into a correlation of dimensionless groups.
Effects of water vapor content on the inflammable limits of ammonia‐oxygen‐nitrogen mixtures
Authors: Decoursey W. J. , Zubryckyj N. , Yoshida N. 
Published: February 2011

AbstractA study was undertaken to confirm and extend available information on the inflammable limits of ammonia in air or oxygen‐nitrogen mixtures, and particularly the effects of water vapor on these limits. Such information should prove helpful in the prevention of explosion in equipment handling these gas mixtures, for example in the autoclaves for leaching of nickel sulphide concentrate under pressure, with ammonia and compressed air. Flame‐quenching technique was used for determinations at atmospheric pressure, and the dynamic bomb method at ten atmospheres.At atmospheric pressure, the inflammable limits of ammonia in dry air were found to be 17.2 and 30.2% ammonia, but these limits were found to narrow as the water vapor is increased, until at 10.8% H2O and 20.8% NH3 no flame could survive. With a dry oxygen‐ammonia mixture, the lower limit was found to be 15.2% ammonia. At ten atmospheres, the explosive limits of ammonia in dry air were found to be 16.9 and 28%, and these limits were narrowed with addition of water vapor until, above 9% water, no explosion occurred.
A correlation of mass transfer data of solid‐liquid systems in agitated vessels
Authors: Marangozis J. , Johnson A. I. 
Published: February 2011

AbstractStudies of mass transfer between solids and liquids for agitated vessels have been reviewed. Data from the literature correlated empirically by the Gilliland‐Sherwood correlation, regardless of the actual geometry of the apparatus, in two main categories.The velocity term in the Re number was defined as the velocity of the rotating device, i.e., impeller, cylinder or rotating annulus. The characteristiclength term was taken as the impeller diameter in the cases of mass transfer from suspended pellets or flat surfaces, the gap‐width in the case of rotating cylinders, and the hydraulic radius of the annulus in the case of rotating vessels.The empirical correlations were found to be in general agreement with the turbulent boundary layer mechanism of mass transfer.
Kinetic studies of the thermal decomposition of ferric sulphate and aluminum sulphate
Authors: Warner N. A. , Ingraham T. R. 
Published: February 2011

AbstractKinetic studies were made of the thermal decompositions of ferric sulphate and aluminum sulphate. The reaction product gases were swept from the samples. Cylindrical pellets prepared from chemically pure anhydrous powders were used, and mathematical corrections were made to relate the reaction rate to the area of the interface between the undecomposed sulphate and the oxide product. The interface is the local of the reaction. The rate of the decomposition reaction is proportional to the area of this interface. Studies on ferric sulphate have shown that the rate of decomposition is also directly proportional to the difference between the equilibrium pressure of sulphur dioxide (or oxygen) over the sample and the partial pressure of sulphur dioxide (or oxygen) in the gas stream. The activation energies are 19.9 kcal. and 64.0 kcal. respectively for the ferric sulphate and aluminum sulphate decompositions. No oxysulphates were detected as intermediates in the transition from the normal sulphates to the oxides.
The agglomeration of aqueous suspensions of graphite
Authors: Sutherland J. P. 
Published: February 2011

AbstractA description is given of a practical technique for producing compact spherical agglomerates from a liquid suspension of solids following a method outlined by Farnand, Smith, and Puddington. This method involves the addition of an immiscible liquid which preferentially wets the solids and forms liquid bonds between colliding particles. Using a rotatingdrum agglomerator, pellets ranging in size from 0.020 to 0.75 in. diameter were produced from an aqueous suspension of finely‐divided graphite. The effects of operating variables such as drum load, speed of rotation, suspension and bridging liquid concentrations are described, followed by a discussion of the mechanism of particle growth. Selective agglomeration is also described.
Ion‐exchange diaphragms for caustic‐chlorine cells
Authors: Chrysikopoulos S. , Tombalakian A. S. , Graydon W. F. 
Published: February 2011

AbstractThe possibility of employing ion‐exchange diaphragms for caustic‐chlorine cells was investigated. Caustic soda of low salt content was produced by batch and by continuous electrolysis of sodium chloride in a two chambered cell separated by a polystyrene sulphonic acid cation‐exchange diaphragm. Caustic soda solutions as high as 41% by weight and containing less than 1/10 of 1% sodium chloride were obtained directly from the electrolysis cell.Measurements also were made to determine the effect of cell operating variables on the energy consumption for this electrolytic process. A marked dependence of energy efficiency on ion‐exchange diaphragm properties, current density, and concentration of caustic soda solution produced was observed. The experimental data were graphically correlated to allow practical interpretation.
Interfacial tension gradients and droplet behavior
Authors: Schechter R. S. , Farley R. W. 
Published: February 2011

AbstractThe rate of droplet settling and mass transfer are known to be quite sensitive to small quantities of surface active impurity present in the interface. The purpose of this paper is to examine critically several of the models used for predicting the rate of inhibited Stokesian settling and to compute the rate of mass transfer from the surface of a slowly settling droplet in the presence of surface active impurities which are distributed over the surface.
Air pollution control with fibre mist eliminators
Authors: Brink J. A. 
Published: February 2011

AbstractDifficult air pollution problems caused by the emission of submicron mists have been solved with fibre mist eliminators. This new equipment is the result of extensive research and development at Monsanto.This paper describes some air pollution problems which have been solved successfully with fibre mist eliminators and suggests some new problems which should be solved in the future.
Simultaneous development of velocity and temperature profiles for laminar flow of a non‐Newtonian fluid in the entrance region of flat ducts
Authors: Yau Joseph , Tien Chi 
Published: February 2011

AbstractThe momentum and energy integral method of von Karman and Pohlhausen is used to solve the entrance heat transfer problem for a non‐Newtonian fluid in a flat duct. The initial temperature and velocity profiles are assumed to be flat. The fluid is assumed to obey the Ostwald‐de Wael model and its physical properties are assumed to be constant. Dimensionless expressions for temperature and velocity profiles are obtained by numerical methods.The results of this investigation indicate that, similar to the case of Newtonian fluid, the parameters which influence entrance heat transfer are x/b ratio, Reynolds number and Prandtl number, provided these groups are properly defined.
Coalescence of drops in liquid‐liquid extraction columns
Authors: Smith A. R. , Caswell J. E. , Larson P. P. , Cavers S. D. 
Published: February 2011

AbstractObservations have been made of the presence of coalescence within an operating spray liquid‐liquid extraction column, and of the ease or difficulty of coalescence at the column interface. On the basis of a mechanism proposed to explain coalescence and checked against the observations, qualitative predictions can be made as to ease of coalescence for ternary situations where a solute is transferred between two liquids, each saturated with the main component of the other.
Pressure‐temperature critical loci for multicomponent hydrocarbon mixtures
Authors: Grieves Robert B. 
Published: February 2011

AbstractBased upon data reported in the literature, pressure‐temperature critical loci are presented for the methane‐ethane‐n‐butane and ethane‐n‐butane n‐pentane systems. Loci are drawn having fixed values of a composition parameter including the two heavy components of the system. The curves closely resemble the bounding binary loci. Based upon accurate methods of calculating critical temperatures (0.5%) and critical pressures (1.5%), critical loci are presented for the ethane‐propane‐n‐butane‐n‐pentane system. Two families of curves are generated, each family corresponding to a fixed value of the composition parameter including the heaviest components. Each curve corresponds to a constant ratio of propane, n‐butane, and n‐pentane (and to fixed values of two composition parameters). Relations are noted between binary and multicomponent mixtures containing a constant mole fraction of light component, and the concept of a pseudo‐heavy component is discussed. For a fixed value of the heavy component composition parameter, triangular composition diagrams with curves of constant critical temperature and constant critical pressure are presented for the ethane‐propane‐n‐butane‐n‐pentane system. Linear critical temperature parameters connecting the bounding binary and ternary systems adequately describe the critical temperature behavior of the quartenary system. The critical pressure behavior resembles that of a ternary system.