bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat transfer from a horizontal smooth tube to a laminar falling film
Authors: MitroviC J. 
Published: March 2009

AbstractFor the case in which the liquid, freely falling between two adjacent horizontal tubes, forms a liquid sheet, Rogers (1981) gave an analysis of the heat transfer from the tube to the liquid. The flow within the film was assumed to be laminar. Some of the results obtained by Rogers are extended and discussed in the present paper. In particular, a simple relation is given for the angle θd, at which the thermal boundary layer intersects the film surface. This relation provides an easy means for calculation of the heat transfer coefficient and for determination of the range of parameters in which Rogers' analysis is applicable.
Mixing length equation for high schmidt number mass transfer at solid boundaries
Authors: Grifoll J. , Giralt Francesc 
Published: March 2009

AbstractA simple modification of the Van Driest damping factor for mixing length calculations of mass and/or heat transfer coefficients at solid boundaries is proposed to increase mass eddy diffusivities in the near‐wall region, without affecting velocity predictions. Calculated mass transfer rates with a constant Sct = 0.85 are in good agreement with present and previous experimental results obtained in pipe and duct flows at high Schmidt numbers.
Absorption of carbon dioxide into laminar falling films of aqueous kaolin slurries containing sodium hydroxide
Authors: Hikita Haruo , Ishimi Kosaku , Egawa Akira 
Published: March 2009

AbstractTo confirm the theory for gas absorption accompanied by an instantaneous irreversible reaction in laminar falling films of power‐law liquids which was presented in a previous paper, experiments were carried out on the absorption of pure carbon dioxide into aqueous kaolin slurries containing sodium hydroxide by using a long wetted‐wall column. The experimental data were in fairly good agreement with the theoretical predictions, the average deviation being 3.0%. The discussion on the effect of the power‐law index of the liquid upon the reaction factor suggested an approximate method of estimating the reaction factors for power‐law liquids.
Effect of fluid density on flow in bagged electrowinning cells
Authors: Choo T. C. , Fujisawa T. , Toguri J. M. 
Published: March 2009

AbstractIn bagged electrowinning cells where there is gas evolution at the anode, such as the NiCl2 system, flow across a porous diaphragm bag is observed to occur predominantly from the bottom of the cell. A model based on a hydrostatic argument is proposed which can account for this phenomenon on the basis of bulk density difference between the catholyte and anolyte. Experimental evidence by means of visualization through acid‐base reactions shows good agreement with the model.
Phase behavior measurements of CO2‐SO2‐brine mixtures
Authors: Sayegh S. G. , Najman J. 
Published: March 2009

AbstractPhase behavior and physical property measurements were carried out on mixtures of SO2‐H2O; CO2‐H2O, 5, 10, and 20 weight percent NaCl brines; and ternary CO2‐SO2‐H2O mixtures. The temperature was kept constant at 45°C, while saturation pressures were varied up to about 15 MPa. Binary measurements demonstrated that, at the same temperature and pressure, the mutual solubilities of SO2 and H2O are higher than those of CO2 and H2O. A three‐phase region has been identified in the termary CO2‐SO2‐H2O phase diagram at 7.24 MPa, but no such region was found at higher pressures.
Analysis of reaction zone thickness in non‐catalytic solid‐gas reactions
Authors: Rao T.Rajeswara 
Published: March 2009

AbstractAn expression for determining the reaction zone thickness in a slab type solid pellet is derived based on the grain model for first order and isothermal reaction. It is shown that during reaction, the zone thickness remains constant for slab type pellets and varies for cylindrical and spherical shaped pellets. An approximate criterion is obtained from the expression for the applicability of the widely used shrinking core and homogeneous models. The expression is also useful for determining the rate parameters. The expression is found to be very satisfactory in predicting the experimental reaction zone thickness values and the activation energy value for the zinc sulphide oxidation reaction.
Study of an air‐lift system, Part II: Heat transfer in co‐current, vertical two‐phase, non‐boiling flows
Authors: Grandjean B. P. A. , Ajersch F. , Carreau P. J. , Patterson I. 
Published: March 2009

AbstractHeat transfer at the inner wall for co‐current vertical air‐water mixture flow has been investigated in a 161.5 mm diameter pumping tube of an air‐lift system. The experimental heat transfer coefficients were found to be significantly higher than those calculated from a single liquid phase correlation for the same liquid flow rate. The enhancement of heat transfer was found to be related to the flow pattern. A decrease of the heat transfer coefficient was observed in the transition region from slug flow to churn flow. Hydrodynamic and heat transfer models have been used to describe heat transfer during the slug flow regime and a correlation is proposed for the heat transfer coefficient in the liquid plug behind the gas bubble.
Kinetics of chemical desulphurization of coal in aqueous ferric chloride
Authors: Oshinowo Toks , Ofi O. 
Published: March 2009

AbstractThe kinetics of the chemical desulphurization of Lafia coal by the oxidation of the pyritic sulphur component with aqueous ferric chloride has been investigated. The oxidation rate was found to increase significantly with increasing temperature (60 to 102°C) and ferric chloride concentration (0.2 to 1.0M) but decreased with increasing coal particle size (‐0.210 mm to +0.841 mm). The kinetic data were well described by the unreacted shrinking core model with the indication that the desulphurization was predominantly chemical reaction controlled. The rate of reaction was also found to be well correlated by a two‐parameter pseudo‐homogeneous kinetic model. The specific rate constant obtained showed a true Arrhenius temperature dependence.
Liquid diffusion study by a holographic sandwich method
Authors: Paoletti D. , Spagnolo G. Schirripa , D'Altorio A. 
Published: March 2009

AbstractThe technique of sandwich holography is proposed for the study of diffusion in transparent liquid mixtures. The diffusion coefficient may be measured simply and directly from the interferogram obtained by shearing a sandwich hologram during reconstruction. Some preliminary results for the KCI‐water system are presented.
Conjugate heat transfer with laminar flow in an annulus
Authors: Sakakibara Mikio , Mori Shigeru , Tanimoto Akira 
Published: March 2009

AbstractThe solution to the conjugate heat transfer problem in an annulus with a heated (cooled) core and an insulated outside tube is presented. Three kinds of boundary conditions are considered for a chosen radius ratio.From the results of parametric calculation over a wide range, it is concluded that wall heat conduction in a core can have substantial effects on the heat transfer characteristics in the areas surrounding the beginning and the end of the heat transfer section.
Simulation bidimensionnelle de phénomènes de convection naturelle et forcée en formulation primitive
Authors: Robichaud Michel , Methot J.‐Claude , Dupuis Marc , Dernedde Edgar 
Published: March 2009

AbstractLa simulation numérique en deux dimensions de la circulation de l'air, du profil de température et de pression pour des phénomènes de convection naturelle et forcée a été réalisée grâce à une méthode hybride aux différences finies basée sur la méthode MAC et utilisant la formulation Ψω. Trois problèmes différents ont été résolus: (i) convection forcée dans une enceinte fermée; (ii) convection naturelle dans une enceinte fermée; et (iii) convection naturelle et forcée dans une enceinte avec ouvertures et sources chaudes localisées. Les résultats sont comparés à la littérature pour les deux premiers problèmes et à des résultats expérimentaux obtenus avec une maquette pour le troisième problème.
The periodic steady state for cyclic energy storage in paraffin wax
Authors: Jariwala V. G. , Mujumdar A. S. , Weber M. E. 
Published: March 2009

AbstractThe thermal performance of a latent heat energy storage unit was studied experimentally at the periodic steady state generated by cyclic energy storage and recovery. The periodic steady state was obtained by alternating identical freezing periods with identical melting periods. The storage unit was a cylindrical container of commercial paraffin wax. Energy was transferred to (and from) the wax by temperature controlled water flowing through a submerged helical coil. Measurements were made of the amount of energy stored and recovered as functions of the freezing and melting times, the temperature of water and the geometry of the coil. A simple model was proposed to calculate the energy stored or recovered in the periodic steady state.
Cooling exothermic catalytic fixed bed reactors: Co‐current versus countercurrent operation in a methanol conversion reactor
Authors: Ravella A. , De Lasa H. 
Published: March 2009

AbstractA comparison between two possible designs of exothermic catalytic fixed bed reactors, fully co‐current and fully countercurrent flow, was performed for the process of methanol transformation into hydrocarbons. The fully co‐current operation proved more appropriate, yielding, under low parametric sensitivity, higher productivities and allowing higher inlet methanol partial pressures.The co‐current design showed, in a wide range of operating conditions, the Pseudoadiabatic Regime, a useful mode of operation. The countercurrent design did not allow Pseudoadiabatic Operation and had drawbacks such as multiple steady states and reactor ignition.
The importance of real‐fluid behavior and nonisentropic effects in modeling decompression characteristics of pipeline fluids for application in ductile fracture propagation analysis
Authors: Picard D. J. , Bishnoi P. R. 
Published: March 2009

AbstractThe importance of real‐fluid behavior during the rapid decompression of dense natural gas mixtures has been investigated using existing one‐dimensional models for real‐fluid isentropic decompression (RID) and perfect‐gas isentropic decompression (PID). The results show that the assumption of perfect‐gas behavior may result in significant errors. In the case of ductile fracture propagation (DFP) analyses, the fracture‐tip pressure level may be underestimated by more than 20 percent.A real‐fluid nonisentropic decompression (RND) model has been developed in order to investigate the importance of nonisentropic effects in DFP problems. The results indicate that nonisentropic effects may be neglected for pipe sizes above approximately 508 mm O.D.
Measurement of heat of mixing for ammonium chloride + ammonia system at 25 °c
Authors: Yamamoto Hideki , Sanga Seiji , Tokunaga Junji 
Published: March 2009

AbstractHeat of mixing for ammonium chloride in liquid ammonia at 25°C was determined in the concentration range 0‐50 wt% NH4Cl. It was calculated from the differential heat of solution observed in this work and the differential heat of dilution estimated from activities of solvent. A twin isoperibol calorimeter consisting of two stainless Dewar vessels was used at a relatively high pressure (up to 1.5 MPa). The accuracy of this calorimetry was examined by measuring the heat of solution for tris‐(hydroxymethyl)aminomethane(THAM) in 0.1 kmol/m3 HCl at 25°C, and satisfactory agreement within 1.1% between experimental and literature value was obtained. The reproducibility for the experiment was within 2.8%.
On the modelling of multicomponent acid extraction with long‐chain aliphatic amines
Authors: Stenström Stig , Wingefors Stig 
Published: March 2009

AbstractThe solvent extraction of phosphoric, hydrochloric, sulphuric, hydrofluosilicic and hydrofluoric acids with long‐chain aliphatic amins is modelled. Pure acid equilibria are based on existing isotherms or calculated extraction constants when only experimental data are available. For binary mixtures binary combinations of acid complexes are added. In the aqueous phase Bromley's model for electrolytes is used for calculation of ionic activity coefficients and the appropriate association/dissociation equilibria taken into account for calculation of ionic strength. For the organic phase an empirical model for the non‐ideal behaviour of phosphoric acid is used. For multicomponent mixtures at low acid concentrations the model calculates the extraction of phosphoric, hydrochloric and sulphuric acid almost quantitatively. For hydrofluosilicic and hydrofluoric acid the calculations are less precise and further information is needed about the different fluoride exchange equilibria involved.
Theoretical evaluation of the performance characteristics of a combined hemodialysis/hemoperfusion system — I. Single pass flow
Authors: Lee Chau‐Jen , Chang Yen‐Lin 
Published: March 2009

AbstractA mass transfer model with single pass flow is proposed for evaluating the performance characteristics of a combined system composed of a dialyzer for hemodialysis (HD) and a coated adsorbent packed cartridge for hemoperfusion (HP). In the dialyzer, the mass transfer equation is represented in terms of three dimensionless parameters, i.e., extraction ratio, number of transfer unit, and ratio of flow rates. For the hemoperfusion cartridge, the model equations are derived by formulating the following four processes: convective mass transfer in the bed, fluid phase mass transfer around a coated adsorbent particle, transport across a film of coated membrane, and diffusion within an adsorbent particle. The Freundlich isotherm model is used for the adsorption on adsorbent particles. Applications of the mathematical model to systems to be potentially used in clinical practice are discussed. Solutions for two different sequences of arrangement, i.e., HD‐HP and HP‐HD, are obtained and discussed in terms of their performance efficacies. Theoretical results demonstrate that the HD‐HP arrangement will give better performance in most clinical encounters.
CO2 gasification of wood charcoals derived from vacuum and atmospheric pyrolysis
Authors: Plante P. , Roy C. , Chornet E. 
Published: March 2009

AbstractThe gasification of biomass derived char obtained via vacuum and atmospheric pyrolysis of Populus tremuloides has been studied in the ranges of 725–960°C and 0.1 to 6 MPa. CO2 was used as the oxidizing gas.The results show that char reactivity is influenced by the preheating rates and that pressure effects are significant between 850°C and 950°C. A correlation based on the expression: df/dt = k0{exp(‐E/RT)}(1 ‐ f)afβPyCO2 was used to fit the experimental data.In general, vacuum pyrolysis derived char showed a higher reactivity than atmospheric pyrolysis chars. An explanation based on a higher oxygen content of the vacuum pyrolysis char is suggested.
Kinetic study of isotopic exchange reaction between hydrogen and water vapor over a pt/sdbc hydrophobic catalyst sheet
Authors: Kawakami Koei , Isobe Minoru , Horiki Kanya , Kusunoki Koichiro 
Published: March 2009

AbstractThe isotopic exchange reaction between hydrogen and water vapor was studied for the temperature range 313 K to 353 K using 2.2% platinum supported on a hydrophobic styrene‐divinylbenzene copolymer (SDBC) sheet. With increasing relative humidity, the exchange rate increased, giving a stepped profile with a knee shape, and the reaction order with respect to hydrogen increased from almost zero to first order. In order to explain this unusual behavior, a simple kinetic model was proposed assuming that the water molecules are adsorbed in a multilayer on the platinum surface, and are subject to the exchange equivalent to finite number of layers. On the other hand, this multilayer of adsorbed water inhibits the transfer of HD to the platinum surface.
Decontamination of petroleum sludges by hot water extraction
Authors: Tran Francis T. , Couillard Denis , Rouleau Denis 
Published: March 2009

AbstractThe process of hot water extraction of tar sand was modified and adapted for removal of heavy oil from bottom tank petroleum sludges, and was submitted to a laboratory feasibility study. This process can also be utilized to clean beach sands contaminated by accidental heavy oil spills.In the case of oil contaminated sands, a single stage extraction has yielded a 99% recovery of hydrocarbons and clean sands (containing less than 0.1% of hydrocarbons) which are thus safe to be returned to the environment.In the case of petroleum bottom tank sludge, it was necessary to proceed with a double stage extraction with the addition of a wetting agent. A dosage of a Na2 Si O3 aqueous solution of 1% by weight has proven efficient, allowing an 82% recovery of hydrocarbons, with only 0.5% of hydrocarbons content in the solid residues.
Membrane formation through the phase‐inversion of Poly(vinylidene)/Dimethylformamide solutions. Experimental and theoretical study of evaporative flux
Authors: Francesconi R. , Castellari C. 
Published: March 2009

AbstractThe phase inversion of a polymeric solution is modeled assuming the validity of the diffusion equation and the existence of a mass‐cumulative stagnant film of vapor on the cast membrane. Unlike previous analyses, the model predicts a maximum in the evaporative flux leaving the polymeric solution. A comparison of theory with experiments indicates that the solvent flux is predicted only qualitatively. The discrepancy is probably due to some assumptions introduced, for mathematical tractability, in the model.
Prediction and experimental determination of vapour‐liquid equilibria for benzene + Cyclohexane + 1‐Butanol mixtures at 101.325 kPa
Authors: Arce A. , Bunco A. , Correa A. , Tojo J. 
Published: March 2009

AbstractThis article reports experimentally determined vapour‐liquid equilibrium data for benzene + cyclohexane + 1‐butanol mixtures at constant pressure of 101.325 kPa, and compares the results with those predicted by the group contribution methods ASOG‐KT and UNIFAC and by the Wilson, NRTL and UNIQUAC models after calculation of their adjustable parameters from the corresponding binary systems.
A general correlation for purely viscous non‐newtonian fluids flowing in ducts of arbitrary cross‐section
Authors: Tam K. C. , Tiu C. 
Published: March 2009

AbstractAn alternative correlation for the flow of purely viscous non‐Newtonian fluids in ducts of arbitrary cross‐section is proposed. It involves two dimensionless groups which are

Unique relationships exist between ϕ and Re*G for both laminar and turbulent flows which enable direct predictions of pressure drop from flow rate results or vice‐versa. Excellent agreement between the new correlations and available experimental data for purely viscous non‐Newtonian fluids flowing in circular tubes and square ducts is demonstrated.
Application of different criteria for uniqueness to the tubular reactor problem
Authors: Viuoen H. J. , Van Rensburg N. F. J. 
Published: March 2009

AbstractA new sufficient condition for uniqueness is applied to the tubular reactor problem. The resulting criterion is compared to existing criteria. Better a‐priori estimates of the temperature solution were used to improve estimates on upper bounds for uniqueness. It is shown that these a‐priori estimates bear the primary responsibility for the better results.
Performance of a hydro‐filter — Mass transfer coefficient and gas‐liquid interfacial area
Authors: Uchida S. , Sumiyama M. , Kamo H. 
Published: March 2009

AbstractAn experimental study of the effect of operating conditions on the performance of a hydro‐filter (marble‐bed scrubber) has been conducted. The overall volumetric mass transfer coefficient, KGa, remains constant while the gas flow rate changes in the stable operating regions but increases sharply in the region above the loading point, corresponding to a sharp increase in the total pressure drop of the hydro‐filter. Since the gas flow is turbulent and the liquid flow is laminar under the present experimental conditions, the value of KGa is strongly dependent on the flow conditions of the liquid and its properties, while those of the gas have less effect.The performance of a hydro‐filter as a mass transfer device is shown to be superior to other types of scrubbers although its main drawback is large pressure drop.
Calculation of some thermodynamic properties of gaseous water by means of BWR equation of state
Authors: Grozdanić D. K. , Djordjević B. D. , Tasić A. Ž 
Published: March 2009

AbstractA procedure for estimation of constants in the Benedict‐Webb‐Rubin (BWR) equation of state from experimental P‐v‐T data of methane, ammonia and water is proposed. The new BWR constants for water have been estimated in the range 366 to 1144 K and 0 to 38 MPa. Compressibility factor, enthalpy and entropy for water have been evaluated with average absolute percentage deviations of 0.127, 0.409 and 0.286 respectively. The BWR equation is compared with other simple as well as complex equations in which the constants have been determined in the usual way. In all cases the BWR equation was the most successful.
Analysis of mass and energy balance equations in gas‐solid reactions
Authors: Oǧkuztöreli M. N. , Chambers A. , Özüm B. 
Published: March 2009

AbstractAnalysis of mass and energy balance equations for gas‐solid reactions are of particular importance in the interpretation of micro scale thermo‐gravimetric analysers, laboratory scale drop tube reactor data, and in the modeling of industrial scale reactors. In the present work we investigate the solutions of mass and energy balance equations for highly porous fine particle gas‐solid reactions in a relatively slow chemical reaction regime (chemical reaction control). Linearization of balance equations around the steady‐states does not provide a satisfactory approximation of the phenomena under consideration, implying that higher order terms are needed for a more accurate description of the process.
Catalytic reactions of n‐hexane on HY zeolite
Authors: Abbot J. , Wojclechowski B. W. 
Published: March 2009

AbstractCatalytic reactions of n‐hexane on HY zeolite have been studied at 500°C. An examination of initial product selectivities shows that monomolecular processes are dominant. These include cracking to produce either C3 + C3 or C2 + C4 and skeletal isomerization. Bimolecular cracking processes account for only ∼ 5% of the total initial selectivity.Methane was identified as an initial reaction product, but its formation is due to concurrent thermal processes. Molecular hydrogen was observed only as a secondary product.The conversion of n‐hexane was fitted by a kinetic model previously applied to various n‐alkanes in the range C8 ‐ C16. In all these cases, the model shows that adsorption of reactants is strongly inhibited by product olefins. Addition of small amounts of olefin to the n‐hexane feed had no accelerating effect, which does not confirm results of previous studies.
Effects of anisotropic scattering of radiation in laminar forced convection in a parallel‐plate duct
Authors: Tsai J. R. , Özisik M. N. 
Published: March 2009

AbstractEffects of anisotropic scattering to heat transfer in hydrodynamically‐developed, thermally‐developing steady laminar forced flow of a gray fluid between two infinite parallel plates are investigated for the case when the inlet temperature of the fluid is less than the wall temperature. An implicit finite difference scheme is applied to solve the energy equation, while the high order PN method is used to solve the radiation part of this problem. The effects of the anisotropy, the conduction‐to‐radiation parameter, the optical thickness, the reflectivity of the plates and the inlet temperature on the local Nusselt number are studied.