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New Correlation (new + correlation)
Selected AbstractsReactor Modeling of Gas-Phase Polymerization of EthyleneCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 11 2004A. Kiashemshaki Abstract A model is developed for evaluating the performance of industrial-scale gas-phase polyethylene production reactors. This model is able to predict the properties of the produced polymer for both linear low-density and high-density polyethylene grades. A pseudo-homogeneous state was assumed in the fluidized bed reactor based on negligible heat and mass transfer resistances between the bubble and emulsion phases. The nonideal flow pattern in the fluidized bed reactor was described by the tanks-in-series model based on the information obtained in the literature. The kinetic model used in this work allows to predict the properties of the produced polymer. The presented model was compared with the actual data in terms of melt index and density and it was shown that there is a good agreement between the actual and calculated properties of the polymer. New correlations were developed to predict the melt index and density of polyethylene based on the operating conditions of the reactor and composition of the reactants in feed. [source] Low-cost J-R curve estimation based on CVN upper shelf energyFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 8 2001K. Wallin J-R curve testing is costly and difficult. The results may also sometimes be unreliable. For less demanding structures, J-R curve testing is therefore not practical. The only way to introduce tearing instability analysis for such cases is to estimate the J-R curves indirectly from some simpler test. The Charpy-V notch test provides information about the energy needed to fracture a small specimen in half. On the upper shelf this energy relates to ductile fracture resistance and it is possible to correlate it to the J-R curve. Here, 112 multispecimen J-R curves from a wide variety of materials were analysed and a simple power-law-based description of the J-R curves was correlated to the CVNUS energy. This new correlation corresponds essentially to a 5% lower bound and conforms well with the earlier correlations, regardless of the definition of the ductile fracture toughness parameter. [source] Fluid flow and heat transfer in the transition process of natural convection over an inclined plateHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 8 2001Katsuo Komori Abstract The present study deals with fluid flow and heat transfer in the transition process of natural convection over an inclined plate. In order to examine the mechanism of the transition process, experiments on the flow and heat transfer were performed for various plate inclination angles in the range of 20 to 75°. The wall temperature and fluid flow fields were visualized using a liquid crystal sheet and fluorescent paint, respectively. The visualization confirmed that separation of a boundary layer flow took place, and the onset point of streaks appeared over the plate wall when the modified Rayleigh number exceeded a characteristic value for each inclination angle. The local Nusselt number in the transition range was proportional to the one-third power of the local modified Rayleigh number. By introducing a nondimensional parameter, a new correlation between visualizations of the flow and temperature fields and heat transfer was proposed. © 2001 Scripta Technica, Heat Trans Asian Res, 30(8): 648,659, 2001 [source] Prediction of entrance length and mass suction rate for a cylindrical sucking funnelINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 6 2010Dipti Prasad Mishra Abstract Conservation equations for mass, momentum and energy have been solved numerically for a cylindrical funnel with louvers (lateral openings on the side wall of the cylindrical funnel through which air can come into it) to compute the suction rate of air into the funnel. The nozzle placed centrally at the bottom of the cylinder ejects high-velocity hot gaseous products so that atmospheric air gets sucked into the funnel. The objective of the work is to compute the ratio of the rate of mass suction to that of the mass ejected by the nozzle for different operating conditions and geometrical size of the funnel. From the computation it has been found that there exists optimum funnel diameter and optimum funnel height for which the mass suction is the highest. The protruding length of the nozzle into the funnel has almost no effect on the mass suction rate after a certain funnel height. The louvers opening area has a very high impact on the mass suction rate. The entrance length for such a sucking funnel is strikingly much lower compared with a simple cylindrical pipe having uniform flow at the inlet at same Reynolds number. A new correlation has been developed to propose the entrance length for a sucking pipe, the rate of mass suction into it and the exhaust plume temperature over a wide range of operating parameters that are normally encountered in a general funnel operations of naval or merchant ship. Copyright © 2009 John Wiley & Sons, Ltd. [source] Modeling heterogeneous downward dense gas-particle flowsAICHE JOURNAL, Issue 5 2010Regis Andreux Abstract A novel approach is proposed to model heterogeneous downward dense gas-particle flows. The homogeneous behavior of the flow is described by the mass and momentum transport equations of the gas and particulate phases solved using a mono-dimension finite volume method on staggered grids. The heterogeneous features of the flow are predicted simultaneously using the bubble-emulsion formalism. The gas compressibility is taken into consideration. The model is supplemented with a new correlation to account for the wall-particle frictional effects. The predictions are compared with the vertical profiles of pressure and the amount of gas that flows up and down two standpipes and a cyclone dipleg of an industrial fluid catalytic cracking unit and of a cold small-scale circulating fluidized bed. The trends are well predicted. The model gives further information and is thus an innovative starting point for downward dense gas-particle flow hydrodynamics investigation. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Unified model for nonideal multicomponent molecular diffusion coefficientsAICHE JOURNAL, Issue 11 2007Alana Leahy-Dios Abstract Multicomponent diffusion is important in a variety of applications. In order to calculate diffusion flux, molecular diffusion coefficients are required, where fluid nonideality and the multicomponent nature of the mixture have a significant effect. A unified model for the calculation of diffusion coefficients of gas, liquid and supercritical states of nonpolar multicomponent mixtures is presented. A new correlation is proposed for the binary infinite dilution-diffusion coefficients. The generalized Vignes relation is used in multicomponent mixtures. Nonideality is rigorously described by the fugacity derivatives evaluated by the volume-translated Peng-Robinson equation of state. Predictions for highly nonideal gas and liquid multicomponent mixtures demonstrate the reliability of the proposed methodology. © 2007 American Institute of Chemical Engineers AIChE J, 2007 [source] Prediction of two-phase pressure drop and liquid holdup in co-current gas,liquid downflow of air,Newtonian systems through packed bedsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2006Ponnan Ettiyappan Jagadeesh Babu Abstract The dependency of pressure drop and liquid holdup on phase velocities, geometry of the column and packing materials as well as on the physical properties have been analyzed. Our experimental data (825 data points obtained using four liquid systems and three different particles) along with those of the available literature (776 data point from five different sources) were used for the analysis. The applicability and the limitations of the literature correlations were evaluated using the available data. Based on the analysis, new correlations for the estimation of pressure drop and liquid holdup, valid for low and high interaction regimes have been developed using the available data, with a wide range of variables. Copyright © 2005 Society of Chemical Industry [source] Mass transfer during air humidification in spouted bedsTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 2 2009Andrzej Kmiec Abstract This article presents the results obtained from analysing the impacts of bed media, static bed height, and the water-to-air mass flow ratios on the mass transfer coefficient and Colburn factor. The experimental data were compared with the correlations for mass transfer and the analogy between heat and mass transfer in conical spouted beds described earlier in literature. Moreover, the aim of the article is to present some new correlations of dimensionless groups for description of mass transfer and analogy of heat and mass transfer in sprayed spouted beds, which were developed by the authors. Cet exposé présente les résultats obtenus suite à l'analyse de l'impact du médium et de la hauteur statique du lit, des rapports d'écoulement de la masse eau-air sur le coefficient de transfert de masse et le facteur de Colburn. Les données expérimentales ont été comparées aux corrélations pour le transfert de masse et à l'analogie entre le transfert de chaleur et de masse dans des lits jaillissants coniques décrits plus tôt dans la documentation. En outre, le but de l'article est de présenter quelques nouvelles corrélations de groupes adimensionnels, développées par les auteurs, en vue de décrire le transfert de masse et l'analogie du transfert de chaleur et de masse dans les lits jaillissants pulvérisés. [source] | |||||||||||||