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Modeling of Fluidized Bed Gasification:Assessment of Zero-dimensional and CFD Approaches

Journal of Thermal Science 2015年第4期24卷 378-385页

作者： nuno couto Valter Silva Eliseu Monteiro P.S.D.Brito Abel Rouboa University of Tras-os-Montes and Alto Douro INEGI/Faculty of Engineering University of Porto C3i-Interdisciplinary Center for Research and Innovation Polytechnic Institute of PortalegreLugar da AbadessaApartado 1487301-901PortalegrePortugal MEAM Department University of Pennsylvania

In modeling fluidized bed gasification experiments,equilibrium and CFD models are valuable *** existence of multi-dimensional effects inside the reactor vessel due to the kinetics of the process and the fluid dynamics phenomena could result in deviation from the zero-dimensional *** models integrating kinetics and hydrodynamics are being developed by using a computer fluid dynamics(CFD)*** objective of this investigation is to assess and compare the adequacy of zero-dimensional and CFD approaches in modeling fluidized bed gasification regarding a semi-industrial scale(numerical results are validated under experimental runs).Results show that the zero-dimensional model based on the approach of dual stage equilibrium performs reasonably well in adequately predicting the product gas composition at different operating conditions and for different feedstocks,although with quantitative ***,the discrepancy depends on the oxygen content of the oxidation agent and on the steam-to biomass ratio decreasing when these parameters *** models provide deeper information being able to estimate the syngas composition or other operating parameter at any point of space and *** of some quantitative discrepancy,the zero-dimensional modeling approach is deemed satisfactory from the viewpoint of the determining design conditions simulation.

关键词：计算机流体动力学流体力学模型流化床气化零维模型气化模型 CFD模型结合动力学数值模拟

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Computational Fluid Dynamics Analysis of Greenhouses with Artificial Heat Tube

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World Journal of Mechanics 2012年第4期2卷 181-187页

作者： nuno couto Abel Rouboa Eliseu Monteiro José Viera Department of Engineering Universidade de Trás-os-Montes e Alto Douro Vila Real Portugal Department of Mechanical Engineering and Applied Science University of Pennsylvania Philadelphia USA Research Department of Agriculture Secretary Lisbon Portugal

With the workmanship decrease in farms, the necessity to rationalize the use of other inputs and the development of technology has rapidly expanded the use of computer simulation in agricultural systems. One of the agricultural systems in which the modeling process of plant growth has been more engaged is the greenhouse production for horticultural crops. In Mediterranean climate, it is during the night that the energy losses are important and can be compensated with an artificial heat input. In this work an experiment was performed in a greenhouse in the north of Portugal. Temperature values in several points and air velocity in the aperture were measured during the night for three different cases: natural convective heating (case A);artificial heating tubes (AHT) (case B);AHT and natural ventilation (case C). A CFD simulation, carried out using FLOTRAN module of ANSYS, was also performed in two-dimensional configuration to obtain the indoor air temperature and velocity fields for the three cases. A very good agreement between experimental and numerical temperature values were verified, which allows to validate the adopted numerical procedure. In case A, the average temperature was 2.2℃. An average increase of 6.7℃ and 3.5℃ on the air temperature was obtained for the case B and case C, respectively. These results clearly emphasis the influence of each thermal load on greenhouse indoor air properties.

关键词： Greenhouses Artificial Heating Tubes CFD Finite Element Method

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