bluuebunny/crossref_metadata_2025_split huggingface dataset:
Limits of superheat and explosive boiling of light hydrocarbons, halocarbons, and hydrocarbon mixtures
Authors: Porteous William , Blander Milton 
Published: June 2004

AbstractThe limits of superheat of thirteen light hydrocarbons and four light halocarbons were experimentally measured at one atmosphere using a superheating column. While there was some variation in the number of degrees to which a compound could be superheated before boiling explosively, in all cases the reduced limits TL/Tc were close to 0.88. The measured superheat limits of three binary hydrocarbon systems and several ternary mixtures were close to mole fraction averages of the limits of the pure components. The results of both pure components and mixtures paralleled predictions of Beegle (1973), based on thermodynamic stability theory. Limits of pure components agreed closely with limits predicted from homogeneous nucleation theory.
Sulfur dioxide oxidation in slurries of activated carbon. Part I. Kinetics
Authors: Komiyama Hiroshi , Smith J. M. 
Published: June 2004

AbstractDynamic adsorption and reaction studies were made for the catalytic oxidation of sulfur dioxide in aqueous slurries of activated carbon at room temperature and atmospheric pressure. For the small particles (dp = 0.03 mm) of carbon used, mass transfer resistances were of minor importance so that the data could be analyzed in terms of the kinetics of the chemical reaction. Quantitative evaluation of mass transfer effects, including intraparticle diffusion, is presented in Part II.The rate was first order in oxygen concentration in the liquid and zero order with respect to SO2. The rate decreased with increasing H2SO4 concentration in the liquid. This was explained by the decrease in solubility of oxygen in the solution rather than by a change in reaction rate constant. The adsorption and rate data together suggest that the controlling step in the mechanism is the adsorption of oxygen on active sites of the carbon surface. The low concentration of oxygen in water (due to its low solubility) reduces its rate of adsorption.
Continuous production of polystyrene in a tubular reactor: Part I
Authors: Wallis J. P. A. , Ritter R. A. , Andre H. 
Published: June 2004

AbstractAn experimental analysis of the bulk polymerization of styrene initiated by azobisisobutyronitrile was carried out in a tubular reactor.The experiments performed in a 2.362‐cm I.D., 6‐meter long jacketed reactor showed that: (1) it was feasible for a tubular reactor to produce acceptable quality polystyrene for industrial purposes; (2) the quality of the polymer product was reproducible at any time; (3) it was technically feasible for the tubular reactor to replace the stirred‐batch kettles as the preliminary stage in the polystyrene manufacturing process, and (4) radial temperature gradients were not a problem for reactor operation.
Trickle‐bed reactor performance. Part I. Holdup and mass transfer effects
Authors: Goto Shigeo , Smith J. M. 
Published: June 2004

AbstractLiquid holdup and mass transfer rates were measured in a 2.58‐cm I.D. tube, packed with glass beads and granular CuO · ZnO catalyst or β‐naphthol particles, and operated as a trickle bed. Gas‐to‐liquid (water) transport coefficients were determined from absorption and desorption experiments with oxygen at 25°C and 1 atm. Liquid‐to‐particle mass transfer was studied using β‐naphthol particles.Holdup and both mass transfer coefficients were unaffected by gas flow rate but increased with liquid rate. The data were correlated with equations that could be used for predicting mass transfer coefficients at high temperatures and pressures for use in the reaction studies reported in Part II.
Trickle‐bed reactor performance. Part II. Reaction studies
Authors: Goto Shiego , Smith J. M. 
Published: June 2004

AbstractDilute solutions (132 ppm) of formic acid in water were oxidized with air in a trickle‐bed reactor at 212° to 240°C and 40 atm. Particles 0.291 and 0.0541 cm in diameter, prepared from a commercial CuO · ZnO catalyst, were used to provide a model system for studying water purification by catalytic oxidation.Differential reactor runs were made to measure the global rate of reaction. These data were compared with predicted rates from the known intrinsic kinetics and intraparticle diffusivities, and the mass transfer coefficients measured in Part I.High conversion (of formic acid) data were also obtained in order to test models for trickle‐bed reactors. Experimental conversions agreed reasonably well (within 10%) with predicted values based upon intrinsic kinetics and the several transport rates. Axial dispersion was found to be less important than gas‐to‐liquid mass transfer and intraparticle diffusion. In our laboratory studies (reactor I.D. = 1 in.) careful arrangements were made to obtain nearly uniform distribution of liquid over the reactor cross section. Hence effects of maldistribution, which may be important in large‐scale reactors, were minimized.
Stresses and friction force in moving packed beds
Authors: Grossman Gershon 
Published: June 2004

AbstractA model to determine stresses and friction forces in moving packed beds with interstitial fluid flow has been developed. The scaling parameters are determined from the governing equations. A plane and an axisymmetric bed geometry are studied and the wall stress calculated under uniform one‐dimensional axial flow conditions. The effect of added transverse flow (for example, due to a screen in the wall) is investigated. The present model is an improvement over earlier, one‐dimensional models with capability to include in the stress analysis varying pressure gradients in all directions which may exist in practical moving bed systems.
Diffusion and reaction in turbulent flow of a power‐law fluid in a circular tube
Authors: Mohan V. , Raghuraman J. , Wasan D. T. 
Published: June 2004

AbstractSimultaneous diffusion and homogeneous reaction during the turbulent flow of a power‐law fluid in a tubular reactor has been studied using the correlations for the velocity profile and eddy diffusivity proposed by Krantz and Wasan. The results of the theory indicate that while the cup‐mixing concentration is unaffected by variations in the Reynolds number, the Schmidt number, or the flow behavior index, it is significantly influenced by the reaction parameter and the reaction order.
Mechanics of steady spinning of a viscoelastic liquid
Authors: Denn Morton M. , Petrie Christopher J. S. , Avenas Pierre 
Published: June 2004

AbstractThe equations for steady isothermal spinning of a viscoelastic liquid are solved for a fluid model with constant modulus and a single constant relaxation time. High stress levels are predicted for elastic liquids, and the velocity approaches a linear profile in the limit of maximum drawdown. These predictions are in accordance with the observed behavior of polymeric liquids in isothermal spinning. Relaxation times computed from spinning data of Spearot and Metzner and Acierno et al. for four low density polyethylene melts are comparable to those measured rheogoniometrically, though the spinning relaxation times are 20 to 80% larger.
Ecokinetics: A study of the fate and distribution of chemicals in laboratory ecosystems
Authors: Blau G. E. , Neely W. B. , Branson D. R. 
Published: June 2004

AbstractThe anticipated kinetic behavior of different amounts or forms of a chemical in the environment can be studied by introducing the chemical into a laboratory ecosystem, collecting samples of the different components of the system at various times, and obtaining a sequence of concentrations of the chemical and/or its metabolites. Conventional compartmental models can be used to characterize this concentration‐time data in order to better predict the distribution and ultimate fate of a chemical introduced into the environment, to provide a quantitative measure for helping assess the environmental impact of different chemicals, and to reduce the cost of expensive laboratory testing and field work.
A Deborah number for diffusion in polymer‐solvent systems
Authors: Vrentas J. S. , Jarzebski C. M. , Duda J. L. 
Published: June 2004

AbstractA Deborah number is introduced as a means of characterizing diffusional transport in amorphous polymer‐solvent systems. Two types of temperature‐penetrant concentration diagrams are constructed, and the various regions on these figures are identified by their Deborah number values. The utility of the diffusion Deborah number is demonstrated by using this dimensionless group to anticipate conditions under which thickness anomalies can be expected in sorption experiments for the atactic polystyrenepentane system.
Phase separation of primary dispersions in beds packed with spherical packings
Authors: Wilkinson David , Mumford C. J. , Jeffreys G. V. 
Published: June 2004

AbstractStudies have been made of the behavior of drops in primary dispersions flowing through beds packed with glass ballotini in order to establish the mechanism of phase separation. The buoyancy and surface forces have been analyzed in terms of drop size and shape in the interstice in the packing and the physical properties of the dispersion. A mathematical model has been developed to describe drop behavior in the bed, and the drop size in the effluent dispersion has been predicted from established correlations.
Self‐generated oscillations in continuous crystallizers: Part I. Analytical prediction of the oscillating output
Authors: Yu K. M. , Douglas J. M. 
Published: June 2004

AbstractThe theory of nonlinear oscillations should provide a useful tool for studying both forced and self‐generated oscillations in continuous crystallizers. The application of the theory is described in this paper for the case of self‐generated oscillations in a MSMPR (mixed‐suspension, mixed product removal) isothermal crystallizer. Although the process parameters do not correspond to typical industrial conditions, the results indicate that for the Class I system studied higher yields sometimes can be obtained from the periodic process than the steady state design. Thus, there may be some situations where oscillatory operation is advantageous.
Flow phenomena in stirred tanks. Part II. The bulk of the tank
Authors: Günkel Alfred A. , Weber Martin E. 
Published: June 2004

AbstractTurbulence parameters were measured in the bulk of turbulent stirred tanks of 45.7 and 91.4 cm diameter with air as the working fluid. Three types of turbine impellers were studied ranging in diameter from 22.8 to 45.7 cm. The turbulence in the bulk of the tank was essentially homogeneous and isotropic. The normalized one‐dimensional energy spectra and the Eulerian autocorrelation functions were approximately the same throughout the tank and for all tanks, impellers, and operating conditions. The space averaged turbulent velocities were correlated by using the turbulent energy equation. A transformation of the measured spectra from the frequency space to the wave number space was accomplished. Integration of the dissipation spectra in the wave number space confirmed that most of the energy input is dissipated in the bulk of the tank through the turbulent motion. The results were extended to low viscosity liquid systems and used to interpret the data on mass transfer from suspended particles.
Model discrimination and parameter estimation in heterogeneous catalysis
Authors: Froment G. F. 
Published: June 2004

AbstractAfter a brief discussion of the experimental aspects of a kinetic investigation, the paper reviews the methodology of kinetic analysis, for both single and complex reactions. The necessity of statistical testing of the results is emphasized. Special attention is given to methods for estimating parameters in algebraic and differential equations. Sequential methods for the design of an experimental program aiming at optimal discrimination between rival models and optimal parameter estimation are reviewed and illustrated by means of practical examples.
Flooding rates and holdup in packed liquid‐liquid extraction columns
Authors: Watson J. S. , McNeese L. E. , Day John , Carroad P. A. 
Published: June 2004

AbstractCountercurrent flow of liquids in columns packed with Raschig rings was studied with fluids having a wide range of physical properties. These results, along with data reported previously from other studies, were used to develop a correlation for predicting flooding rates in packed columns that is significantly better than previous correlations. Dispersed phase holdup in packed columns can be estimated over a wide range of flow rates or flow ratio by assuming a constant slip velocity between the two phases which is dependent on the properties of the fluids and packing used. Although the slip velocity is thus essentially constant at flow rates below flooding, the flooding rate correlation indicates that this term is not necessarily constant at flooding conditions.
Pyridine hydrodenitrogenation: An equilibrium limitation on the formation of piperidine intermediate
Authors: Satterfield Charles N. , Cocchetto Joseph F. 
Published: June 2004

AbstractEquilibration between pyridine and piperidine, the first product formed in the overall series of hydrodenitrogenation (HDN) reactions of pyridine, can be a rate‐limiting factor under some conditions. Thus, on a commercial NiMo/Al2O3 catalyst at 11 bars pressure, a maximum in the pyridine HDN rate occurs at about 400°C, caused by a thermodynamic limitation on the allowable concentration of piperidine. From studies with pyridine and with piperidine, NiMo/Al2O3 appears to have greater hydrogenation‐dehydrogenation activity than CoMo/Al2O3 but CoMo/Al2O3 appears to have greater hydrogenolysis activity than NiMo/Al2O3, at least at about 300°C and below.
Benzoin‐ and benzoin methyl ether‐sensitized photopolymerization of styrene and methyl methacrylate: Quantum yields and mixing effects
Authors: Mendiratta S. K. , Felder R. M. , Hill F. B. 
Published: June 2004

AbstractStyrene and methyl methacrylate have been polymerized in a batch photoreactor using two sensitizers–benzoin (C6H5COCHOHC6H5) and benzoin methyl ether (C6H5COCHOCH3C6H5)–and light with a peak intensity at 366 nm. Primary quantum yields have been calculated for each monomer‐sensitizer combination. Effects of mixing on the rate of polymerization and product molecular weight distribution have been determined and correlated with a two‐region reactor model.
Perturbed hard‐chain theory: An equation of state for fluids containing small or large molecules
Authors: Beret Samil , Prausnitz J. M. 
Published: June 2004

AbstractGeneralized van der Waals theory is used to establish a partition function that considers the effect of density on rotational and vibrational motions in addition to translational degrees of freedom. A three‐parameter equation of state is derived from this partition function. The equation of state is applicable to small, spherical (argon‐like) molecules and also to large, structurally complex molecules, including polymers. Parameters are presented for three polymers and twenty‐two common fluids including light hydrocarbons, heavy hydrocarbons, nitrogen, carbon dioxide, hydrogen, carbon monoxide, hydrogen sulfide, sulfur dioxide, and water. The equation of state gives good liquid densities, and vapor pressures, and fair second virial coefficients.
The decomposition kinetics of molybdenite in an argon plasma
Authors: Munz R. J. , Gauvin W. H. 
Published: June 2004

AbstractA reactor system was developed for the study of heterogeneous reaction kinetics in plasma tail flames. This system was used to investigate the thermal decomposition kinetics of stationary particles of molybdenum disulfide in both the molten and solid state when exposed to argon flames in the temperature range 3 000°K to 8 000°K.In the solid state a shrinking‐core reaction model was obeyed. The rate of reaction was largely controlled by the diffusion of sulfur vapor outwards through the product layer. An apparent activation energy of 134 kcal/mole was calculated for the particle temperature range 1 613° to 1 833°K The molten state reaction was controlled by the rate of heat transfer to the reacting particle. Calculations indicated that the rate of heat transfer was influenced by the efflux of sulfur.
A coordinate‐transformation method for the numerical solution of nonlinear minimum‐time control problems
Authors: Kwon Young D. , Evans Lawrence B. 
Published: June 2004

AbstractA new method is presented for the numerical solution of nonlinear minimum‐time control problems where at least one of the state variables is monotone. A coordinate transformation converts the problem with fixed end point and free end time to one of free end point and fixed end time. The transformed problem can be solved efficiently by the use of the gradient method with penalty functions to force the system to achieve target values of state variables. Application of the method is illustrated by the synthesis of a minimum‐time temperature path for the thermally initiated bulk polymerization of styrene.
Cis‐1,4 polymerization of butadiene initiated by CoCl2 · 4C5 H5 N‐(C2 H5)2 AlCl
Authors: Hsu C. C. , Ng L. 
Published: June 2004

AbstractThe effect of catalyst composition on the polymerization of butadiene initiated by CoCl2 · 4Py‐Et2AlCl‐H2O in a batch reactor has been studied. It was found that the polymerization is first order with respect to monomer and cobalt concentrations, and both the deactivation of catalyst and the chain transfer reaction have great influence in conversion as well as molecular weight. A general conversion model was proposed, and it fits the experimental data well.
Friction coefficients for bubbly two‐phase flow in horizontal pipes
Authors: Kopalinsky Eleonora M. , Bryant R. A. A. 
Published: June 2004

AbstractFriction coefficients determined from an experimental study of the flow of bubbly two‐phase mixtures in horizontal pipes are used, together with a homogeneous theory, to establish a method for the prediction of the static pressure drop in this class of flows.
On the fate of fuel nitrogen during coal char combustion
Authors: Wendt J. O. L. , Schulze O. E. 
Published: June 2004

AbstractThe physical and chemical characteristics that influence the conversion of fuel nitrogen to nitrogen oxides during coal char combustion were theoretically examined by using a simplified model in which nitric oxide is an intermediate product between fuel nitrogen and N2.It was found that diffusion‐reaction interactions were important in determining the selectivity of the char particle toward nitric oxide production. At low temperature fluidized bed combustion conditions, pore size is important, and low conversion of fuel nitrogen to nitric oxide is favored by long narrow pores. Under high temperature, pulverized coal combustion conditions, the model provided insight into mechanisms of nitric oxide formation and predicted the observed weak temperature dependence of fuel nitrogen conversion, as well as a significant effect of particle size.
Secondary nucleation of ice in sugar solutions and fruit juices
Authors: Stocking James H. , King C. Judson 
Published: June 2004

AbstractFrom thermal response measurements, ice nucleation rates in distilled water, sugar solutions, and fruit juices were determined for a stirred, batch‐seeded crystallizer. High resolution thermometry permitted use of initial sub‐coolings between 0.01° and 0.2°K. Nucleation increased with approximately the second power of subcooling. Applications to freeze concentration are considered.
Multipass flow distribution and mass transfer efficiency for distillation plates
Authors: Bolles William L. 
Published: June 2004

AbstractA new model for predicting the hydrodynamics, flow distribution, and mass transfer efficiency of multipass distillation trays is presented. Separate submodels apply to two‐, three‐, and four‐pass trays, which may be any type of cross flow tray with downcomers: sieve, valve, or bubble cap.It was found that the liquid/vapor flow ratio in one pass of a poorly designed multipass tray can be several times that in adjacent passes, and that the mean tray efficiency of such a tray is substantially less than the optimum possible. It is shown that multipass trays can be designed with essentially perfect flow distribution and optimum (maximum) overall tray efficiency.
An interferometric technique for the study of steady state membrane transport
Authors: Min Sengwoo , Duda J. L. , Notter R. H. , Vrentas J. S. 
Published: June 2004

AbstractA membrane wedge interferometer was designed for obtaining steady state mass transfer data on liquid‐membrane‐liquid systems. Procedures were developed for analyzing the diffusive transfer process, and experiments were conducted on the ethyl alcohol‐water‐cellophane membrane system to obtain the type of data needed for elucidating mechanisms of membrane transport. The proposed technique provides an accurate method of studying membrane transport without the troublesome complications which characterize other methods.
A mechanism supported by extensive experimental evidence to explain high heat fluxes observed during nucleate boiling
Authors: Mesler Russell 
Published: June 2004

AbstractThis paper attempts to elucidate the mechanism responsible for high heat transfer rates occurring in nucleate boiling when liquid films exist on the heating surface. High‐speed cinematography and simultaneous transient surface temperature measurements provide a basis for describing the mechanism. In a liquid film, bubbles grow and detach rapidly. The film is quickly renewed. A liquid microlayer exists beneath a bubble its entire life. Conditions are very favorable for rapid evaporation from the microlayer so that heat transfer is rapid. A number of independent observations by other investigators working on diverse problems are cited in support of the mechanism.
Constitutive equation for vapor drift velocity in two‐phase annular flow
Authors: Ishii Mamoru , Chawla T. C. , Zuber Novak 
Published: June 2004

AbstractA constitutive equation for a vapor drift velocity which specifies the relative motion between phases in the drift flux model is developed for two‐phase annular flows. The constitutive equation is derived by taking into account the interfacial geometry, the body force field, and the interfacial momentum transfer, since these macroscopic effects govern the two‐phase diffusions. A comparison of the model with three sets of experimental data obtained over a wide range of flow parameters shows a satisfactory agreement.
Practical realizations in process modeling: Part II. The approximation problem
Authors: Jayaraman Krishnamurthy , Lapidus Leon 
Published: June 2004

AbstractThe composite algorithm derived in Part I is used to construct models from pulse responses of lumped and distributed systems, as well as an empirically measured residence time density. Along the way, salient points in the numerical implementation of the algorithm are indicated. In the present recursive procedure, the initial transient is predicted accurately by lower‐order partial realizations; successive partial realizations involve progressively longer tails of the pulse response. The zeroth moment of the impulse response is used to advantage when realizations with no zeros are appropriate.
Mathematical models of the monolith catalytic converter: Part I. Development of model and application of orthogonal collocation
Authors: Young Larry C. , Finlayson Bruce A. 
Published: June 2004

AbstractThe orthogonal collocation method is applied to solve the mathematical model of a monolith catalytic converter, in which the reaction takes place in a porous catalytic layer deposited on the wall of a tube. A sequence of models is developed, with the most complicated one involving transient heat and mass transfer in three dimensions.