Papers by Keyword: Fluid Dynamic

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Authors: Yi Yi Wu, Xiao Gang Yang, Xiao Bing Huang, Vincent Barrioz, Shafiul Monir, Stuart Irvine, Giray Kartopu
Abstract: A CFD numerical model has been established to study the growth of cadmium telluride (CdTe) on substrate using metalorganic chemical vapour deposition technique in atmospheric pressure (AP-MOCVD) and hydrodynamics in an inline MOCVD reactor. The numerical simulations have been conducted using the CFD code – ANSYS Fluent. Dimethylcadmium (DMCd) and diisopropyltelluride (DIPTe) have been employed as precursors while H2 is acting as the carrier gas. In order to assess the effect of various conditions on CdTe film growth and uniformity, heat transfer and mass transport behaviours of the chemical species in the reactor have been fully investigated. In addition, material utilization and fluid dynamics in the reactor are also discussed.
Authors: Elisabete R. Silva, J.M. Silva, Fernando A. Costa Oliveira, M. Fatima Vaz, M. Filipa Ribeiro
Abstract: Reticulated cordierite foams produced by a direct foaming method were successfully washcoated with platinum-based zeolite catalysts. For comparison purposes, commercial cordierite monoliths were also washcoated. The effect of the structural properties on the fluid dynamics and catalytic behaviour for the toluene combustion were evaluated. Foam supports revealed highest performances, in terms of conversion into CO2, when compared to conventional honeycomb monoliths. The experimental results suggest that the catalytic behaviour is critically dependent on the fluid dynamics provided by structural characteristics of the supports, such as porosity, density and size of pores. The randomness and tortuosity of foams enhance reactant mixing, as it was evidenced by the higher axial and radial dispersions of the gas flow across the foam structure. This leads to better mass and heat transfers in the reaction system, thus improving the catalytic behaviour.
Authors: Ping Liu, Qing Pei Ou, Hong Bo Zhou, Min Li
Abstract: Non-contact seal assembly for high-speed shaft ends is introduced. Fluid dynamic calculations and analyses have been made with FLUENT Software on the flowing in the front sealed cavity, the mid labyrinth-sealed cavity and the outside windshield cavity of the seal assembly. The results through the tests are in conformity with those in simulation analyses.
Authors: Frédéric Mercier, Shin Ichi Nishizawa
Abstract: We investigated numerically fluid dynamics and carbon transport in a 2 inches SiC solution growth with the presence of alternative magnetic fields. Buoyancy and Marangoni convection are taken into account. Our numerical results revealed that the magnetic field parameters have a strong impact on the melt convection. We also propose a solution to increase the mass transfer at the crystal growth front.
Authors: Sandra Mara Santana Rocha, Luiz Gustavo Martins Vieira, M.L. Aguiar, João Jorge Ribeiro Damasceno
Abstract: The new environmental laws, as well as the search for technologies of accuracy production, have leaded companies to search for more and more efficient equipment. Regarding the emission of particulate material, the fabric filter is the most used equipment in the industry, for presenting a high efficiency and low operational costs, essential in any project of this type. In the search for a more efficient and economic filtering operation, this work studied, by techniques of CFD, the modification of the traditional way of feeding a filtering box (usually accomplished by the side of the system) by another in which the feeding was accomplished through the bottom of the equipment, in order to review the distribution of volumetric outflows in the bags and pressure drop. The fluid dynamic simulations had shown that the feeding fluid - through the bottom of the filtering box - provides an inferior operational pressure drop and a better distribution of fluids between the bags.
Authors: Qing Chang Meng, Zhi Hong Zhang, Ju Bin Liu
Abstract: A finite volume method has been formulated based on the ideal compressible potential theory. By using the continuity equation and Tait state equation as well as Riabouchinsky closure model, an "inverse problem" solution has been presented for the supercavitating flow. According to the impenetrable condition on the surface of supercavity, a new iterative method for the supercavity shape has been designed to deal with the effect of compressibility on supercavity shape and pressure field. The supercavity shape changes from ellipse to taper, as well as the drag coefficient increases with Mach number increasing. The results compare well with the experiment data and empirical formula, and the numerical method is proven to be valid.
Authors: Chuan Zhen Zhao, Li Yuan Yu, Chun Xiao Tang, Ming Li, Jian Xin Zhang
Abstract: The paper reports the setting up of a model of fluid dynamic for GaN HVPE system and the simulation. The deposition of GaN with the variation of the gas flow inlet velocities is investigated. The influence of diffusion coefficient on the deposition of GaN is also discussed. It is found that the influence of the gas flow inlet velocities on the deposition is large and the influence of diffusion coefficient on the deposition of GaN is small in vertical HVPE.
Authors: Frédéric Mercier, Didier Chaussende, Jean Marc Dedulle, Michel Pons, Roland Madar
Abstract: The main problem for the development of 3C-SiC electronics is the lack of an adapted bulk growth process. The seeded sublimation method is not very adapted for the 3C polytype because of the solid-state transition from cubic to hexagonal that occurs at high temperature (above 1800°C). In this paper, we propose a new experimental set-up for the development of a solution route for the growth of high quality 3C-SiC crystals. By a coupled approach involving experiments and global process modeling, we have addressed the problems of dissolution and crystallization, elimination of parasitic nucleation and stabilization of the growth front. With an appropriate control of the different convection mechanisms, a stable growth front is demonstrated, with a growth rate of a few tens of µm/h at 1650°C. Further improvements and potentialities of this approach are discussed.
Authors: E.B. Arruda, J.M.F. Façanha, L.N. Pires, A.J. Assis, Marcos A.S. Barrozo
Abstract: Rotary dryers are commonly used to dry particulate in a range of food and mineral processing industries. The purpose of this work was to study the design and performance of a rotary dryer. It was evaluated the number of flights and operational conditions that corresponding to the optimal performance for the equipment. A set of equations to predict the solids holdup in flights with three and two segments was also evaluated. Their predictions were compared to measurements performed with a pilot plant rotary dryer. The equation generated very accurate estimations.
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