scholarly journals A Mixing Behavior Study of Biomass Particles and Sands in Fluidized Bed Based on CFD-DEM Simulation

Energies ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1801 ◽  
Author(s):  
Heng Wang ◽  
Zhaoping Zhong
Keyword(s):  
Fluidized Bed ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Gas Velocity ◽  
Three Dimensional Model ◽  
Large Size ◽  
Behavior Study ◽  
Mixing Behavior ◽  
Computational Fluid Dynamics Cfd ◽  
Biomass Particles

The present paper studied the mixing characteristics of biomass and sands in a fluidized bed. A three dimensional model is calculated on the basis of computational fluid dynamics (CFD) and the discrete element method (DEM), while the lab-scale experiments under similar conditions are conducted. To investigate the mixing behavior of biomass and sands, particle distribution, particles time averaged kinetic motion and the Lacey index are analyzed and the effects of gas velocity and biomass size are discussed. Gas velocity provides the basic motion for particle movement and biomass particles gain a lot more kinetic motion than sands due to their large size. The biomass mixing process in a horizontal direction is more sensitive to gas velocity than in a vertical direction. Biomass size could slightly affect the mixing quality and a well mixing in fluidized bed could be reached if the size of biomass to sands is smaller than 4 times.

3D Numerical Simulation of Polydisperse Pressurized Gas-Solid Fluidized Bed

2011 ◽  
Author(s):  
P. Fede ◽  
O. Simonin ◽  
I. Ghouila
Keyword(s):  
Numerical Simulation ◽  
Fluidized Bed ◽  
Ethylene Polymerization ◽  
Solid Phase ◽  
Three Dimensional ◽  
Gas Velocity ◽  
Particle Segregation ◽  
3D Numerical Simulation ◽  
Model Predictions ◽  
The Mean

Three dimensional unsteady numerical simulations of dense pressurized polydisperse fluidized bed have been carried out. The geometry is a medium-scale industrial pilot for ethylene polymerization. The numerical simulation have been performed with a polydisperse collision model. The consistency of the polydisperse model predictions with the monodisperse ones is shown. The results show that the pressure distribution and the mean vertical gas velocity are not modified by polydispersion of the solid phase. In contrast, the solid particle species are not identically distributed in the fluidized bed indicating the presence of particle segregation.

scholarly journals RAS-NAAD: 40-yr High-Resolution North Atlantic Atmospheric Hindcast for Multipurpose Applications (New Dataset for the Regional Mesoscale Studies in the Atmosphere and the Ocean)

2020 ◽  
Vol 59 (5) ◽  
pp. 793-817 ◽  
Author(s):  
Alexander Gavrikov ◽  
Sergey K. Gulev ◽  
Margarita Markina ◽  
Natalia Tilinina ◽  
Polina Verezemskaya ◽  
...  
Keyword(s):  
High Resolution ◽  
Ocean Circulation ◽  
North Atlantic ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Lateral Boundary Condition ◽  
Three Dimensional Model ◽  
Free Atmosphere ◽  
The North ◽  
The North Atlantic

AbstractWe present in this paper the results of the Russian Academy of Sciences North Atlantic Atmospheric Downscaling (RAS-NAAD) project, which provides a 40-yr 3D hindcast of the North Atlantic (10°–80°N) atmosphere at 14-km spatial resolution with 50 levels in the vertical direction (up to 50 hPa), performed with a regional setting of the WRF-ARW 3.8.1 model for the period 1979–2018 and forced by ERA-Interim as a lateral boundary condition. The dataset provides a variety of surface and free-atmosphere parameters at sigma model levels and meets many demands of meteorologists, climate scientists, and oceanographers working in both research and operational domains. Three-dimensional model output at 3-hourly time resolution is freely available to the users. Our evaluation demonstrates a realistic representation of most characteristics in both datasets and also identifies biases mostly in the ice-covered regions. High-resolution and nonhydrostatic model settings in NAAD resolve mesoscale dynamics first of all in the subpolar latitudes. NAAD also provides a new view of the North Atlantic extratropical cyclone activity with a much larger number of cyclones as compared with most reanalyses. It also effectively captures highly localized mechanisms of atmospheric moisture transports. Applications of NAAD to ocean circulation and wave modeling are demonstrated.

scholarly journals Analysis of Cyclist’s Drag on the Aero Position Using Numerical Simulations and Analytical Procedures: A Case Study

2020 ◽  
Vol 17 (10) ◽  
pp. 3430 ◽  
Author(s):  
Pedro Forte ◽  
Daniel A. Marinho ◽  
Pantelis T. Nikolaidis ◽  
Beat Knechtle ◽  
Tiago M. Barbosa ◽  
...  
Keyword(s):  
Linear Regression ◽  
Numerical Simulations ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Paired Samples ◽  
Computational Fluid Dynamics Cfd ◽  
Analytical Procedures ◽  
Previous Training ◽  
Very High

Background: Resistance acting on a cyclist is a major concern among the cycling fraternity. Most of the testing methods require previous training or expensive equipment and time-consuming set-ups. By contrast, analytical procedures are more affordable and numerical simulations are perfect for manipulating and controlling inputs. The aim of this case study was to compare the drag of a cyclist in the aero position as measured using numerical simulation and analytical procedures. Methods: An elite male cyclist (65 kg in mass and 1.72 m in height) volunteered to take part in this research. The cyclist was wearing his competition gear, helmet and bicycle. A three-dimensional model of the bicycle and cyclist in the aero position was obtained to run the numerical simulations. Computational fluid dynamics (CFD) and a set of analytical procedures were carried out to assess drag, frontal area and drag coefficient, between 1 m/s and 22 m/s, with increments of 1 m/s. The t-test paired samples and linear regression were selected to compare, correlate and assess the methods agreement. Results: No significant differences (t = 2.826; p = 0.275) between CFD and analytical procedures were found. The linear regression showed a very high adjustment for drag (R2 = 0.995; p < 0.001). However, the drag values obtained by the analytical procedures seemed to be overestimated, even though without effect (d = 0.11). Conclusions: These findings suggest that drag might be assessed using both a set of analytical procedures and CFD.

Effect of Blade Numbers on Pressure Drop of Axial Cyclone Separators by CFD

2011 ◽  
Vol 55-57 ◽  
pp. 343-347 ◽  
Author(s):  
Yi Gang Luan ◽  
Hai Ou Sun
Keyword(s):  
Pressure Drop ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Three Dimensional Model ◽  
Navier Stokes Equations ◽  
Pressure Drops ◽  
Computational Fluid Dynamics Cfd ◽  
Cfd Method ◽  
Resistance Performance

In this article, computational fluid dynamics(CFD) method is used to predict the effect of blade numbers on the pressure drop of axial cyclone separators. A three-dimensional model is built to acquire the resistance of axial cyclone separators with different blade numbers. The flow field inside cyclone separators is calculated using 3D Reynolds-averaged Navier-Stokes equations. And turbulence model is used to simulate the Reynold stress. Also pressure drop of cyclone separators with different blade numbers is expressed as a function of different inlet velocities. At the same inlet velocity with increasing the blade numbers, pressure drops of cyclones reduce greatly. And changing the blade number of cyclone separator is an effective method to improve its resistance performance.

Comparisons on Flow and Temperature Fields for Water-Collecting Box of Diesel Exhaust System

2011 ◽  
Vol 199-200 ◽  
pp. 1532-1536 ◽  
Author(s):  
Xiao Chuan Wang ◽  
Guo He ◽  
Xing Long Pan ◽  
Xiao Ying Shi
Keyword(s):  
Sea Water ◽  
Reverse Flow ◽  
Temperature Drop ◽  
Three Dimensional ◽  
Exhaust System ◽  
Temperature Fields ◽  
Exhaust Gas ◽  
Three Dimensional Model ◽  
Computational Fluid Dynamics Cfd ◽  
Storage Cells

The storage cells of conventional submarines are usually charged up by in the snorkeling state, when the diesel engines that charge the storage cells work underwater. The reverse flow of sea water into the diesel engine from the exhaust pipelines can be avoided effectively by using a water-collecting box (WCB), which has other functions as well. In this paper, a three-dimensional model of WCB was established and based on which the flow and temperature fields were studied by computational fluid dynamics (CFD) computations. From the comparison of distribution on interior fields for four different structural WCBs, an optimized scheme of enhancing the cooling effect and not raising the exhausting resistance was probed. The results show that the temperature drop of exhaust gas after washing the WCB IV (WCB with truncated tubes) is 40 percent higher than that of the WCB I, and the pressure drop has a low of 3 percent as well. The comprehensive characteristics of WCB IV are foremost between the four WCBs.

The Fitting Formula of Outflow Coefficient for the V-Cone Flow Meter Based on FLUENT

2009 ◽  
Vol 16-19 ◽  
pp. 1199-1202
Author(s):  
De Zhi Sun ◽  
Xiao Ying Chen ◽  
Wei Li Liu
Keyword(s):  
Cone Angle ◽  
Three Dimensional ◽  
Effective Diameter ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Flow Meter ◽  
Technical Parameters ◽  
Fluent Software ◽  
Computational Fluid Dynamics Cfd ◽  
High Temperature Steam

The V-cone flow meter is widely used to measure gas, liquid and high temperature steam in current industrial production. By applying the FLUENT software of CFD, a three-dimensional model about the V-cone flow meter is built. The effect of technical parameters on flow in the V-cone flow meter field has been studied by using computational fluid dynamics (CFD). The data fitting for empirical formula of the outflow coefficient was completed by using MATLAB software to provide some basis for the further production and exploration. The simulation outflow coefficient is relevant to the parameter of the effective diameter ratio , the diameter of pipe D, front-cone angle and back-cone angle .

3-D Modeling of Liquid Injection into Fluidized Beds

2004 ◽  
Vol 2 (1) ◽  
Author(s):  
Joachim Werther ◽  
Stefan Bruhns
Keyword(s):  
Fluidized Bed ◽  
Flow Structure ◽  
Three Dimensional ◽  
Fluidized Bed Reactors ◽  
Three Dimensional Model ◽  
Liquid Injection ◽  
Bubbling Fluidized Bed ◽  
Solids Mixing ◽  
Semi Empirical ◽  
Bubble Splitting

A three-dimensional model has been developed to describe the injection of liquid reactants into fluidized bed reactors operating in the bubbling fluidized bed regime. The model considers the processes of liquid transport and evaporation in the vicinity of the point of injection. The underlying idea, which is supported by previous measurements, is that the particles in the dense suspension phase are wetted by the liquid or gas-liquid spray. The wetted particles are subsequently dried while they are following the gross solids circulation within the bed. The model considers the flow structure of the bubbling fluidized bed and the solids mixing with the aid of a hybrid model which combines semi-empirical models for bubble growth by coalescence and for bubble splitting with a CFD approach for the continuous emulsion phase surrounding the bubbles. Submodels for heat and mass transfer are used to describe the temperature and concentration fields in the vicinity of the injection nozzle and the drying process of the wetted particles with the resulting release of the vaporized injection liquid. The model was validated separately against flow structure measurements, solids tracer measurements and experiments with the injection of water and ethanol, respectively, into beds of FCC particles.

Multidimensional modelling of anaerobic granules

2005 ◽  
Vol 52 (1-2) ◽  
pp. 501-507 ◽  
Author(s):  
C. Picioreanu ◽  
D.J. Batstone ◽  
M.C.M. van Loosdrecht
Keyword(s):  
Three Dimensional ◽  
Molecular Techniques ◽  
Computational Domain ◽  
Charge Balance ◽  
Three Dimensional Model ◽  
Biofilm Model ◽  
Granule Structure ◽  
Biomass Particles ◽  
Multidimensional Modelling

A multispecies, two- and three-dimensional model was developed, based on a previously published planar biofilm model, and the biochemical structure of the ADM1. Several soluble substrates diffuse and react in the granule. Local pH is calculated from acid-base equilibria and charge balance. The model uses individual-based representation of biomass particles within the granule (biofilm), and describes spreading by an iterative pushing technique. The overall computational domain consists of one granule, and is divided into a grid with Cartesian coordinates. The number of grid elements does not limit the number of biomass particles, and it is not necessary to use grid-spreading techniques, such as cellular automata, which result in Cartesian artefacts. The model represents both microscopic and macroscopic features in granule structure, previously observed using in-situ molecular techniques, and can be effectively used to interpret these results.

Hydrodynamics Simulation of Gas-Solid Flow Field in Conveying Vessel

2011 ◽  
Vol 236-238 ◽  
pp. 1528-1531
Author(s):  
Yue Cui ◽  
Hong Gao ◽  
Jin Sheng Sun ◽  
Xu Chen
Keyword(s):  
Flow Field ◽  
Uniform Distribution ◽  
Volume Fraction ◽  
Dead Zone ◽  
Solid Volume Fraction ◽  
Three Dimensional ◽  
Gas Velocity ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Solid Flow

Flow field of gas and particles in a conveying vessel is investigated by use of a three-dimensional model combined Eulerian approach. Because of the nozzles’ arrangement in this study, the flow patterns of spouts and bubbles can be seen in the gas-solid flow field, which lead to a non-uniform distribution of gas velocity. Solid volume fraction is high near the bottom and low at the top part. The porosity rises with gas speed increasing, as well as time. An improvement is examined to remove the dead zone at the bottom, which results in particles remaining.

An Investigation on Ventilation of Building-Integrated Photovoltaics System Using Numerical Modeling

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Siu-Kit Lau ◽  
Yong Zhao ◽  
Stephen Siu Yu Lau ◽  
Chao Yuan ◽  
Veronika Shabunko
Keyword(s):  
Three Dimensional ◽  
Three Dimensional Model ◽  
Cell Temperature ◽  
Cavity Depth ◽  
Air Cavity ◽  
Building Integrated Photovoltaics ◽  
Geometric Configurations ◽  
Flow Disturbances ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

Abstract This study numerically investigates the thermal behavior and airflow characteristics of the building-integrated photovoltaic (BIPV) façade. A three-dimensional model is developed based on the typical BIPV façade. Computational fluid dynamics (CFD) with the shear stress transport (SST) κ-omega turbulent model is used in the study. The effects of geometric configurations on the BIPV cell temperature in steady state are evaluated including the sizes of the bottom and top openings and the depth of the back air cavity (or so-called cavity depth). When the sizes of the inlet and outlet openings are the same, the effects on the decrease of cell temperature are limited. By enlarging the bottom (inlet) opening, the impact of ventilation in the cavity behind is more significant and the cell temperature decreases. Cavity depth is also a vital factor affecting BIPV cell temperature. The paper identifies the optimal cavity depth of approximately 100–125 mm. Flow disturbance and a vortex may be observed at the bottom and top of the air cavity, respectively, as the cavity depth increases which negatively affects the ventilation causing these flow disturbances to increase the cell temperature. Thermal effects of environmental conditions are compared with regard to two selected BIPV configurations. The wind velocity and the attack angle also have an obvious impact on cell temperature. Ambient temperature and solar irradiance exhibit a linear relationship with BIPV cell temperature as expected.

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