bluuebunny/crossref_metadata_2025_split huggingface dataset:
A model for microencapsulation in polyurea shell by means of interfacial polycondensation
Authors: Sirdesai Mayur , Khilar Kartic C. 
Published: March 2009

AbstractA quasi‐steady state model, based on two parallel modes of diffusion and a polycondensation reaction at the inside surface of a microcapsule, is formulated to compute the time of this microencapsulation process. The predicted times of encapsulation are in agreement with observed values reported in patents. It is also shown that, for small shell thickness, the process is reaction‐controlled.
Economic aspects of wood‐burning installations
Authors: Fels M. , Cooper D.F. , Patterson M.N. 
Published: March 2009

AbstractEconomic data were obtained from 15 industrial wood burners. The capital cost was correlated by:Cost = $7870 (kW)0.59.Operating cost varied between $ 0.64 and $ 2.65 per kWhr output, payback times between 3.5 and 11 years and internal rates of return between 6.3% and 28%. Using average values of economic parameters, these results were recalculated on a common basis as a function of wood and electricity costs.
Solubility of H2S and CO2 in sulfolane
Authors: Roberts B. E. , Mather A. E. 
Published: March 2009

AbstractThe solubility of H, S and CO2 in sulfolane (tetrahydrothiophene‐1, 1—dioxide) has been measured at 40°C and 100°C at pressures up to 2350 kPa and 5900 kPa respectively. The Henry's constants obtained from the data are in agreement with those of Rivas and Prausnitz.
Displacement of bitumen from reconstituted oil sands by aqueous solutions
Authors: Margeson J. L. , Hornof V. , Neae G. H. , Faurschou D. K. 
Published: March 2009

AbstractA simple method has been developed for modelling the recovery of bitumen from packed beds of oil sand by water or caustic solution displacement. Batches of reconstituted oil sand were prepared by intimately mixing predetermined amounts of sand, water, and bitumen, thereby permitting the composition of the oil sand to be controlled and varied within a wide range. Dilution of the bitumen with hexadecane facilitated the mixing process and allowed experiments to be performed at low temperatures while maintaining oil‐water viscosity ratios comparable to those prevailing at the higher temperatures encountered during hot water or steam displacements in the field. The effects of a wide range of compositional and operational variables were studied using a two‐level fractional factorial design technique and the findings are discussed. Of particular interest are the observations that the density and initial connate water saturation of the oil sand exert significantly more effect on bitumen recovery efficiency for the case of water displacement than for caustic solution displacement.
Optimal design of a heat exchanger undergoing reaction fouling
Authors: Fryer P. J. , Hobin P. J. , Mawer S. P. 
Published: March 2009

AbstractThe design of heat exchangers which resist fouling is examined. It is shown that for asymptotic reaction fouling in a uniform wall temperature exchanger with outlet fluid temperature kept constant, it is possible to obtain an optimum combination of exchanger size and tube‐side temperature. This optimum minimises the amount of fouling in the system. An equation which gives a good approximation to the optimum is derived, and its limitations discussed.
Reactions of cyclopentane on HY Zeolite
Authors: Abbot J. , Wojciechowski B. W. 
Published: March 2009

AbstractThe reaction of cyclopentane has been studied on HY zeolite at 500°C. Initial reaction processes included ring cleavage to acyclic C5 species, and cracking to produce fragments in the range C1 ‐ C4. Hydrogen transfer accompanied those processes, so that paraffins as well as olefins were observed as initial products. Cyclopentene was formed as an unstable initial product by the dehydrogenation of the feed, although molecular hydrogen was not found as a primary product. Other dehydrogenated species initially formed included coke and aromatics in the range C6 ‐ C10.
A general solution for the transient response of heterogeneous continuous‐flow stirred reactors
Authors: Datta Ravindra 
Published: March 2009

AbstractA general time‐domain analytical solution is provided for the step‐response of a continuous‐flow stirred reactor containing catalyst particles of arbitrary shape in which one‐dimensional diffusion and first‐order irreversible reaction is assumed to occur. The results reduce to the corresponding known solutions for the planar, cylindrical and spherical geometries.
Tube‐wall reactor modelling for multiple reaction networks with non‐linear kinetics and volume change
Authors: Goyal S. K. , Esmail M. N. , Bakhshi N. N. 
Published: March 2009

AbstractTube‐wall reactors are gaining importance for highly exothermic and fast chemical reactions because of their simple construction and improved temperature control. A generalized mathematical model of the non‐isothermal annular tube‐wall reactors for simultaneous catalytic reactions with mixed type non‐linear reaction kinetics and volume change is developed. Numerical solutions of two‐dimensional component transfer equations, heat transfer equation and fluid flow equation may be obtained with appropriate boundary conditions using a recently developed orthogonal collocation method for annular geometries. The model has been successfully applied to the tube‐wall reactors for the Fischer‐Tropsch Synthesis. Comparison between model predictions and previous experimental results is good.
Kinetics of methyl tertiary butyl ether synthesis catalyzed by ion exchange resin
Authors: Al‐Jarallah Adnan M. , Siddiqui Mohammed A. B. , Lee A. K. K. 
Published: March 2009

AbstractThis paper presents the results of an experimental investigation of the kinetics of liquid phase reaction between methanol and isobutene, catalyzed by an acidic ion‐exchange resin, to form methyl tertiary butyl ether (MTBE). A one litre Parr batch reactor was used. Experiments were carried out at 70, 80, 90 and 100°C and at pressures sufficient to maintain liquid phase at those temperatures. Initial methanol/isobutene mole ratios of 1.0 and 2.0 were used. The catalyst amount was also varied.These kinetic data were used to model the reaction kinetics, by non‐linear least squares regression technique. The reaction was found to follow Rideal‐Eley kinetics. The values of the rate constants are reported.
Studies of the fischer‐tropsch synthesis on a cobalt catalyst i. evaluation of product distribution parameters from experimental data
Authors: Sarup B. , Wojciechowski B. W. 
Published: March 2009

AbstractTwo models describing the distribution of linear and monomethyl alkanes in Fischer‐Tropsch products from a cobalt catalyst are formulated. Distribution parameters for monomethyl isomers are derived by assuming either a post‐branching effect on linear chain growth or a decreasing reactivity toward branching with increasing chain length. Distribution parameters for each of the models have been extracted from an extensive experimental data set. We find that the experimental results are well represented by both the models.A “break” in the distribution of linear paraffins has also been observed and is modelled as a sum of the yields of two Anderson‐Schulz‐Flory distributions. We postulate that the two chain growth processes which produce the distributions are governed by two kinds of termination.
Study of the hydrodynamics within a draft tube spouted bed system
Authors: Matthew Mani C. , Morgan Morris H. , Littman Howard 
Published: March 2009

AbstractTwo dimensional Darcy and Ergun models are used to describe the hydrodynamics within the annulus of a spouted bed equipped with a draft tube. Experimental pressure and stream function data for water spouting are shown to be in good agreement with theoretical predictions. Verification of a general spout‐annulus interfacial boundary condition is also established and it is shown that the entry region below the draft tube functions as a classical spouted bed. In addition, an experimental procedure for determining the location of the spout‐annulus interface is presented. Fluid residence time distributions are calculated for a few cases of practical interest.
Hydrogen production by the catalytic steam reforming of methanol: Part 3: Kinetics of methanol decomposition using C18HC catalyst
Authors: Amphlett J. C. , Mann R. F. , Weir R. D. 
Published: March 2009

AbstractThe rate of catalytic decomposition of methanol in the presence of steam has been studied using a commercial CuO‐ZnO‐Al2O3. low temperature shift catalyst from 150‐270°C at one atmosphere pressure in a fixed bed reactor. Mole ratios of steam to methanol of 0.66. 1.0 and 1.5 and catalyst mass to molar feed rate ratios of 25 to 1025 kg. s. mol −1 were utilized. The data were correlated and equations developed to successfully predict methanol conversions and carbon monoxide concentrations in the product gas stream over the temperature range studied. No evidence of mass transfer limitations was observed.
On boundary conditions to the film model of mass transfer in chemical absorption
Authors: Starzak Maciej , Ledakowicz Stanisuw 
Published: March 2009

AbstractThe problem of appropriate boundary conditions for mass transfer within the liquid film in chemical absorption ih reconsidered. It has been shown that the most general solution to the problem of mass transfer in the liquid film can be obtained if a fixed bulk composition is taken as a film‐bulk boundary condition to the differential balance equations of the film. This method leads to solutions which can be incorporated into absorber balance equations of any type. As an illustrative example, the simultaneous absorption of two gases which react together in a semi‐batch absorber is discussed. A new, approximate but very simple and accurate solution to this problem is proposed.
Viscosity and surface tension of p‐xylene‐ethylacetate liquid mixtures
Authors: Narayan Jyoti , Wanchoo R. K. , Razna G. K. , Wani G. A. 
Published: March 2009

AbstractExperimental density, viscosity and surface tension data are reported for p‐xylene‐ethylacetate mixtures at 20°. 30° and 40°C. over the entire composition range. The presence of interactions has been studied in the light of excess properties.
The importance of real‐fluid behavior in predicting release rates resulting from high‐pressure sour‐gas pipeline ruptures
Authors: Picard D. J. , Bishnoi P. R. 
Published: March 2009

AbstractThe real‐fluid nonisentropic decompression model presented by Picard and Bishnoi (1988) has been used to evaluate the current practice of assuming perfect‐gas behavior when predicting release rates from high‐pressure sour‐gas pipelines. It is shown that use of perfect‐gas theory can result in the transient release rate being underestimated by 30 to 45 percent, and the total amount of fluid released, underestimated by 50 percent. Furthermore, perfect‐gas theory cannot consider condensation effects; more than 35 percent of the H2 S contained in a pipeline may be emitted as a liquid.Use of the popular “double exponential” model, as presented by Wilson (1979), will result in similar errors. However, if the model is modified slightly so that the initial mass of fluid in the pipeline is determined based on real‐fluid theory, then a conservative estimate of the transient release rate may be obtained (i.e., the most rapid release of the fluid is predicted).
Studies of the fischer‐tropsch synthesis on a cobalt catalyst II. Kinetics of carbon monoxide conversion to methane and to higher hydrocarbons
Authors: Sarup B. , Wojciechowski B. W. 
Published: March 2009

AbstractSix Langmuir‐Hinshelwood‐Hougen‐Watson models have been derived for the kinetics of conversion of carbon monoxide to hydrocarbons in the Fischer‐Tropsch synthesis. The models were fitted to experimental data obtained in an internal recycle reactor over a wide range of operating conditions. Two models, one based on the hydrogenation of surface carbon and the other on a hydrogen‐assisted dissociation of carbon monoxide as rate limiting steps were both able to provide a satisfactory fit to the experimental rate data.A general model was also developed for the rate of methanation in the presence of higher hydrocarbons. The same two rate limiting assumptions as those used in formulating the rate of total CO conversion are used in these models. The two models were fitted to experimental data for methane formation.It was the model assuming CH formation as rate limiting that showed the best fit for both CO conversion for CH4 formation.
Ignition characteristics of liquid hydrocarbon fuels as single droplets
Authors: Bergeron Carol A. , Hallett William L. H. 
Published: March 2009

AbstractAn investigation into the effects of fuel boiling point and chemical type on the autoignition of single droplets of a number of pure hydrocarbons is reported. Ignition delay times were measured using the suspended droplet technique, and a numerical model was developed to extract reaction rate constants for the fuels. The results show that both fuel boiling point and chemical kinetics are important contributors to the ignition delay.
Nonhydrogenative co‐processing of saskatchewan heavy oil and coal
Authors: Varma R. L. , Bakhshi N. N. , Ranganathan R. 
Published: March 2009

AbstractA Saskatchewan heavy oil was processed with coal additives in a tubular reactor packed with procelain berl saddles at 400–480°C and atmospheric pressure. For comparison purposes, blank experiments in the absence of coal additive were also carried out. The results indicate that considerable reduction in viscosity and increased distillate yields can be achieved by processing heavy oil with coal additive. The API gravity of the liquid product is also improved. Increased amounts of gaseous products with changed composition are obtained in the presence of coal. Under certain conditions, significant dissolution of coal occurs even at the relatively mild conditions used.
Measurement of longitudinal distribution of solids holdup in a three‐phase fluidized bed by ultrasonic technique
Authors: Uchida S. , Katsumata T. , Okamura S. 
Published: March 2009

AbstractA method of measurement of solids holdup in a three‐phase reactor by analyzing the shape and the phase lag or lead of an ultrasonic wave has been proposed. The solids holdup in a solids‐dilute three‐phase fluidized bed could be measured without being affected by the presence of gas bubbles. The experimental values of solids axial dispersivity measured by the ultrasonic technique are in reasonable agreement with an empirical correlation of previous data obtained by other methods. The possibility of the application of the ultrasonic technique to the measurement of solids holdup in a three‐phase fluidized bed has been suggested.
A phenomenological model for heat transfer in freeboard of fluidized beds
Authors: Biyikli Suleyman , Tuzla Kemal , Chen John C. 
Published: March 2009

AbstractA phenomenological model was developed to predict heat transfer to tubes located in the freeboard region of gas fluidized beds. The model is concerned with the conductive/convective mechanism of heat transfer. For high temperature applications, an additional contribution by thermal radiation would need to be incorporated. The model considers that the tube surface experiences alternating contact with a dense emulsion phase and a lean void phase. Contributions by dense and lean phases are represented by transient conduction and convection mechanisms, respectively. Particletube contact information was obtained experimentally for a wide range of operating conditions at room temperature and pressure. Predictions of the model were compared with measured heat transfer coefficients. Over a 20‐fold range in magnitudes of heat transfer coefficients, the model successfully predicted the measured values with an average deviation of 44 percent.
Solids exit discontinuity in slurry bubble columns
Authors: de Bruijn T. J. W. , Reilly I. G. , Macintyre D. , Scott D. S. 
Published: March 2009

AbstractThe exit discontinuity in slurry bubble columns, i.e., the difference in the apparent solids concentration at the very top of the column (Ct) and the concentration in the effluent (Ce), was studied in a 0.3 m ID bubble column, using air as the gas phase, water, a light hydrocarbon oil (Varsol) and trichloroethylene as liquids and glass beads of different sizes and density as solids.The results showed that the drop in solids concentration occurs in a very small layer at the gas/liquid interface. By changing the column exit configuration and removing the gas/liquid interface the exit discontinuity disappeared. The extent of the exit discontinuity depended on the liquid properties and appeared to be related to the foaming tendency of the liquid. In addition, in those systems where the exit discontinuity was significant, it depended on the solids properties and the gas and liquid superficial velocities.
Computation of solid circulation rates in a fluidized bed from tracer particle concentration distributions
Authors: Kececioglu Ifiyenia , Keairns D. L. 
Published: March 2009

AbstractExperimentally measured profiles of tracer particle concentration inside a fluidized bed were employed to calculate rates of bed‐solid circulation induced by the presence of a central jet and by slug motion. Lagrangian minimization and direct pattern search techniques were used to determine the solids transfer rates, which should minimize the error in the tracer particle mass balance while satisfying the bed solid mass balance. Time‐average steady‐state mixing of bed solids and upstream weighting of tracer concentrations were employed in the formulation of the minimization scheme. Quantitative information on solid circulation for three nominal jet velocities of 52, 37 and 25 m/s is provided. The computed solid circulation rates show that there is a region of high circulation around the jet and a region of lower circulation induced by the slug motion.
Monte carlo simulation of a probability screen
Authors: Beeckmans J. M. , Jutan A. 
Published: March 2009

AbstractThe interaction of a probability screen with spherical particles was simulated in a computer model. Repeated runs were made using randomly selected, slightly differing initial conditions, from which the penetration probability was obtained at a particular particle size under given screen operating conditions. The calculations were then repeated with differing particle sizes and operating conditions, and the results were found to compare favourably with experimental data obtained in a previous study. It was shown that the stochastic model correctly predicts the effects of the principal operating variables (screen angle of inclination and aperture size, frequency and amplitude of vibration). Because of excessive computer time requirements of this model a second, semi‐empirical non‐stochastic model was developed whose results closely match those of the earlier model. The second model is suitable for incorporation into a plant simulation computer package.
Laminar mixed convection in the thermal entrance region of horizontal isothermal rectangular channels
Authors: Lin Jenn‐Nan , Chou Fu‐Chu 
Published: March 2009

AbstractLaminar mixed convection in the thermal entrance region of horizontal isothermal rectangular channels for moderate and small Prandtl number (air) is investigated using the vorticity‐velocity formulation of the Navier‐Stokes equation. The numerical results, including the cross‐stream velocity vectors, local Nusselt numbers and local friction factor ratios are presented for the aspect (width/height) ratios 0.5, 1.0 and 2.0, Rayleigh numbers 0 ∼ 2 × 105 and Prandtl numbers 0.7, 5.0 and 100. The strength and pattern of the secondary flow induced by buoyancy effects is found to depend on the magnitude of Rayleigh number and aspect ratio, and the secondary flow leads to a significant enhancement of heat transfer in the entrance region. The classical Graetz problem is shown to be a limiting case which applies only when Ra ≤ 10.3 The behavior of the local Nusselt number for Pr = 100 compares well with the existing results for Pr → ∞.
Power law models as descriptors of the kinetics of complex systems: Temperature effects
Authors: Crickmore Peter J. 
Published: March 2009

AbstractThe effects of temperature on power law models for the kinetics of parallel first order systems are studied. The variation of the empirical power law parameters with temperature provides information on the relationship between the rate constant and activation energy distributions; in particular.if the power law exponent increases with temperature, there is a positive correlation between the rate constants and the activation energies;if the power law exponent decreases with temperature, there is a negative correlation between the rate constants and the activation energies;Arrhenius plots will always be concave unless the activation energies for all the reactions are equal. Application of the techniques described here to data from the catalytic cracking of gas oil over LaY zeolite reveals a compensation effect among the reacting hydrocarbon species.
Maleic anhydride formation from 1, 3‐butadiene oxidation over a vanadia molybdate catalyst
Authors: Lang Xiaosu , Hudgins R. R. , Silveston P. L. 
Published: March 2009

AbstractSteady‐state and transient studies of the partial oxidation of butadiene to maleic anhydride were performed over a Te‐promoted vanadia molybdate catalyst previously used by Fiolitakis et al. (1983) for a study of maleic anhydride production from benzene. Inhibition of the partial oxidation by butadiene was observed. Pathways for CO2 and maleic anhydride formation are different. False‐start behaviour for some products was observed and attributed to conflicting contributions of adsorption and catalyst reduction or oxidation. The reaction mechanism for butadiene differs from that reported from benzene oxidation by Fiolitakis et al. (1983).
Simultaneous correlation of excess gibbs energy and enthalpy of mixing by the UNIQUAC Equation
Authors: Demirel Yasar , Gecegörmez Hatice 
Published: March 2009

AbstractUsing data for excess Gibbs energy, gE, and enthalpy of mixing, hE, temperature dependent parameters of the UNIQUAC equation have been estimated for twenty four systems of binary mixtures. Fifteen of them include data for gE and hE at more than one different isotherm. These parameters are later tested in predicting the gE and hE data simultaneously and representing the effect of temperature on such data. The UNIQUAC equation with temperature dependent parameters represents larger values of maximum heat of mixing than does the UNIQUAC equation with the parameters independent of temperature.
Optimization of non‐steady‐state operation of reactors
Authors: De Tremblay Michele , Luus Rein 
Published: March 2009

AbstractNon‐steady‐state operation of reactors is approached from the optimal control point of view. To find the best type of input, dynamic programming is used. The results show that for some systems, the optimal input is oscillatory in nature as has been found experimentally by others. A modification to conventional dynamic programming is used to avoid the need for interpolation and thus allow high‐dimensional systems to be handled more readily. Three chemical engineering systems of different complexity were considered to test the computational aspect of the approach. In all cases, dynamic programming gives the optimum policy with respect to the period, cycle‐split and amplitude.