DISCRETE PARTICLE SIMULATION OF FLOW PATTERNS IN TWO-DIMENSIONAL GAS FLUIDIZED BEDS

1993 ◽  
Vol 07 (09n10) ◽  
pp. 1889-1898 ◽  
Author(s):  
T. TANAKA ◽  
T. KAWAGUCHI ◽  
Y. TSUJI
Keyword(s):  
Flow Pattern ◽  
Gas Flow ◽  
Distinct Element ◽  
Flow Patterns ◽  
Particle Simulation ◽  
Two Dimensional ◽  
Particle Mixing ◽  
Central Nozzle ◽  
Discrete Particle Simulation ◽  
Gas Fluidized Beds

The flow patterns in two-dimensional gas fluidized bed were simulated numerically by the Distinct Element Method, Gas is issued through the entire width of the base with uniform velocity. Several flow patterns, such as slugging and bubbling, are observed in the results. As the gas flow rate increases, the flow pattern changes from slugging to bubbling. It is confirmed that particle mixing is promoted by bubbling. The flow pattern of bubbling is irregular in comparison with the case of gas injection through a central nozzle which was simulated in our previous study.

scholarly journals NMR Analysis Method of Gas Flow Pattern in the Process of Shale Gas Depletion Development

Geofluids ◽  
2022 ◽  
Vol 2022 ◽  
pp. 1-7
Author(s):  
Rui Shen ◽  
Zhiming Hu ◽  
Xianggang Duan ◽  
Wei Sun ◽  
Wei Xiong ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Pore Pressure ◽  
Shale Gas ◽  
Gas Flow ◽  
Continuous Medium ◽  
Slip Flow ◽  
Flow Patterns ◽  
Transitional Flow ◽  
Analysis Method ◽  
Adsorbed Gas

Shale gas reservoirs have pores of various sizes, in which gas flows in different patterns. The coexistence of multiple gas flow patterns is common. In order to quantitatively characterize the flow pattern in the process of shale gas depletion development, a physical simulation experiment of shale gas depletion development was designed, and a high-pressure on-line NMR analysis method of gas flow pattern in this process was proposed. The signal amplitudes of methane in pores of various sizes at different pressure levels were calculated according to the conversion relationship between the NMR T 2 relaxation time and pore radius, and then, the flow patterns of methane in pores of various sizes under different pore pressure conditions were analyzed as per the flow pattern determination criteria. It is found that there are three flow patterns in the process of shale gas depletion development, i.e., continuous medium flow, slip flow, and transitional flow, which account for 73.5%, 25.8%, and 0.7% of total gas flow, respectively. When the pore pressure is high, the continuous medium flow is dominant. With the gas production in shale reservoir, the pore pressure decreases, the Knudsen number increases, and the pore size range of slip flow zone and transitional flow zone expands. When the reservoir pressure is higher than the critical desorption pressure, the adsorbed gas is not desorbed intensively, and the produced gas is mainly free gas. When the reservoir pressure is lower than the critical desorption pressure, the adsorbed gas is gradually desorbed, and the proportion of desorbed gas in the produced gas gradually increases.

scholarly journals Flow patterns of shallow Palic Lake induced by the dominant winds

2012 ◽  
Vol 10 (1) ◽  
pp. 55-67
Author(s):  
Ljubomir Budinski ◽  
Djula Fabian
Keyword(s):  
Numerical Model ◽  
Flow Pattern ◽  
Coriolis Force ◽  
Wind Direction ◽  
Driving Forces ◽  
Open Water ◽  
Flow Patterns ◽  
Two Dimensional ◽  
Lake Model ◽  
Double Gyre

Studies of lake currents have highlighted that in case of stagnant waters winds are the dominant driving forces. This study is dealing with the influence of dominant winds on the flow pattern of Palic Lake. Action of steady winds of different directions has been tested on the lake by means of a two dimensional numerical model, while in addition to winds all other permanent factors like actual bathymetry, inflow and outflow as well the Coriolis force have been accounted for. The experiments have revealed that winds of different directions created corresponding characteristic flow patterns (in base plot), which were similar in cases of winds having opposite directions. However, in such cases the direction of flow was opposite. Moreover, the Palic Lake model produced the well known double-gyre flow pattern: in the coastal strip the direction of the current corresponded to the wind direction, while it was opposite in the domain of open water.

Numerical Analysis for Heat and Mass Transfer of Granular Flow in a Duct by the Discrete Particle Simulation

2009 ◽  
Author(s):  
Tomohiko Yamaguchi ◽  
Kuniyasu Kanemaru ◽  
Satoru Momoki ◽  
Toru Shigechi ◽  
Ryo Fujiwara
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Energy Equation ◽  
Continuous Phase ◽  
Particle Simulation ◽  
Two Dimensional ◽  
Discrete Particle ◽  
One Dimensional ◽  
Discrete Particle Simulation ◽  
Dimensional Simulation

The solid-gas or liquid-gas two phase flow has many industrial applications such as spray drying, pollution control, transport systems, fluidized beds, energy conversion and propulsion, material processing, and so on. Though the solid-gas multiphase flow has been studied experimentally and numerically, the transport phenomena have not been cleared due to its complexity, computational time and economical costs for the hardware. In this study the heat and mass transfer of solid-gas collision dominated flow is analyzed by the Discrete Particle Simulation (DPS), a kind of the Dispersed Element Method (DEM)[1]. This method describes the discrete phase and the continuous phase by Lagrange and Euler methods respectively, and has been used to simulate the multiphase flow of various geometrical systems. In order to analyze the thermal field we took account of the energy equation and heat conduction between colliding particles. The heat transfer rate is summation of conductive heat transfer and convective heat transfer. Furthermore, the fluid flow has a two dimensional velocity profile, because the void fractions are analyzed as two dimensions. But momentum space has not been resolved by the two dimensional simulation. We call this method, the quasi two-dimensional simulation in this paper. To obtain the temperature distribution of the continuous phase the energy equation is solved in addition to the momentum equations. We treated the interaction between continuous and discrete phases as one and two way couplings. The positions, the momentum and the temperature information of particles and the velocity and the temperature distribution of the fluid were obtained as functions of time from results of these numerical simulations. When the hot air that is suspending small glass particles flows in a duct from bottom up, we traced the particles and got the temperature distribution of fluid and compared with the former results of one-dimensional flow. At the beginning, the cooler particles decrease the fluid temperature near the bottom of the vessel. The temperature profile of the particles obtained by the one-dimensional simulation is as same as quasi two-dimensional simulation. After 0.5 second the particles cool the downstream air. At 1.2 second, particles do not decrease the air temperature because the temperatures of particles are close to the inlet temperature of the air.

The Study of Exhausting Accumulated Liquid in Upward Inclined Pipe Using a Swirl Tool

2019 ◽  
Author(s):  
Zhenqiang Xie ◽  
Xuewen Cao ◽  
Fachun Liang ◽  
Jun Zhang
Keyword(s):  
Flow Pattern ◽  
Cross Section ◽  
Centrifugal Force ◽  
Annular Flow ◽  
Gas Flow ◽  
Swirling Flow ◽  
Flow Patterns ◽  
Gas Production ◽  
Gas Velocity ◽  
The Cross

Abstract The problem of accumulated liquid is very common in wet gas gathering pipelines which varies with the topography, this phenomenon is much more serious especially in upward inclined pipelines. The existence of accumulated liquid at the bottom of the pipeline would decrease the area of the cross section that gas flows through. This makes the gas velocity fluctuate unpredictably and even results in shocks and blocks in pipelines which may cause danger in the safety management of oil and gas production. Swirl tool is a kind of rigid tool which can transfer different flow patterns to a flow pattern similar to annular flow and it has been successfully used to exhaust accumulated liquid in oil fields. However, the mechanism of swirling flow generation in a swirl tool is not fully understood and few researchers have explained how the annular-similar flow decays. In this paper, the formation mechanism of swirling flow in a swirl tool is analyzed using a physical method. The flow pattern transfer procedure and distribution of gas and liquid in the cross section of the pipeline in the swirl tool is simulated with FLUENT (a commercial CFD code). Following the swirling flow formation analysis, the decay of the annular-similar flow from the outlet of the swirl tool is also simulated with FLUENT (a commercial CFD code). Also, the effects of different superficial gas velocities and different liquid rates on the decay of the annular-similar flow are studied with the swirl tool fixed at the bottom of the upward inclined pipeline. The results show that the formation of swirling flow in a swirl tool is mostly affected by the geometric structure of the swirl tool. The centrifugal force is the main force which transfers different flow patterns to a flow pattern similar to annular flow. The centrifugal force that acts on liquid is larger than that of gas since the density of the liquid is much bigger than gas. The annular-similar flow starts to take shape in the swirl tool after the first thread pitch, but the annular-similar flow is nonuniform. After about three thread pitches, the annular-similar flow becomes uniform with liquid surrounding the inner wall of the pipe and gas flowing in the core region of the pipe. The distance of the annular-similar flow sustains longer when the superficial gas velocity increases which means the decay of the swirling flow is slower. Since sufficient liquid rate is critical to maintain annular-similar flow after the tool when the gas flow rate is fixed, the distance of the annular-similar flow goes longer if there is a little increase in liquid rate.

Modelling study of flue gas flow pattern with pressure, amount and shape variation catalytic converter

2020 ◽  
Vol 1 (103) ◽  
pp. 5-17
Author(s):  
A. Ghofur ◽  
H. Isworo ◽  
R. Subagyo ◽  
M. Tamjidillah ◽  
R. Siswanto ◽  
...  
Keyword(s):  
Flow Pattern ◽  
Gas Flow ◽  
Catalytic Converter ◽  
Flow Patterns ◽  
Gas Absorption ◽  
Exhaust Gas ◽  
Shape Variation ◽  
Turbulence Flow ◽  
Converter Design ◽  
Practical Implications

Purpose: The purpose of this study is to analyse the modelling of exhaust gas flow patterns with variations in pressure, number, and shape of filters on the catalytic converter. Design/methodology/approach: The research method used is a simulation using ANSYS, which starts by creating a converter catalytic model with pressure variations: (0.5-1.5 atm), number of filters: (2-5), and the form of filter-cut/filter-not-cut. Findings: The decrease in velocity is caused by non-uniform velocity in the exhaust gas flow that occurs when passing through a bend in the filter-cut that serves as a directional flow to create turbulence. Filter-cut type tends to have fluctuating pressure, turbulence flow pattern shape so that contact between filter and exhaust gas is more effective. Based on the analysis of flow patterns, the speed and pressure of the 5 filter-not-cut design at a pressure of 0.5 are the best, while at pressure (1-1.5 atm) the type 5 filter-cut is the best. Research limitations/implications: This study is limited to filter-not-cut and filter-cut types with variations in the number of filters: 2, 3, 4, and 5, and the inlet pressure between 0.5-1 atm. Practical implications: The practical implications of this study are to find a catalytic converter design that has advantages in the effectiveness of exhaust gas absorption. Originality/value: The results show that the filter-not-cut and filter-cut types have the best effectiveness in the number of 5 filters. Filter-not-cut at the pressure of 0.5 atm and filter-cut at pressure (1-1.5 atm).

Experimental and Model Investigations on Gas Mixing Behaviors of Spout-fluid Beds

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Wenqi Zhong ◽  
Mingyao Zhang ◽  
Baosheng Jin ◽  
Rui Xiao
Keyword(s):  
Flow Pattern ◽  
Flow Rate ◽  
Gas Flow ◽  
Flow Patterns ◽  
Gas Mixing ◽  
Gas Flow Rate ◽  
Dense Region ◽  
Tracer Gas ◽  
Gas Dispersion ◽  
Fluid Bed

Steady-state tracer gas measurements were carried out to study the gas mixing behaviors in a spout-fluid bed with a cross section of 0.3 m x 0.03 m and height of 2 m. Two different tracer gases were simultaneously injected, one was injected into the spouting gas flow and the other was injected into the fluidizing gas flow. Radial tracer gas concentrations at various bed elevations under different flow patterns were measured. The mechanism of gas mixing was discussed based on the racer gas concentrations and the flow patterns recorded by a high-resolution digital CCD camera. It was found that gas mixing in spout-fluid beds was due to both convection and dispersion. A three-region mixing model was developed to describe the gas mixing in the spout-fluid bed. The spout jet region and the boundary region were modeled with a mass transfer model; the annular region was modeled with a dispersion model. Effects of spouting gas and fluidizing gas flow rate on the gas exchange between the spout jet and the annular dense region, and the gas dispersion in the annular dense region were examined with flow patterns. The results showed that increase in spouting gas velocity and fluidizing gas flow rate could both promote the gas mixing in spout-fluid beds. The gas-solid flow pattern transited from internal jet to spouting to spout-fluidizing, and the gases were better mixed. But the gases became poorly mixed when the flow pattern transited from stable flow to instable flow.

An Inlet Area for Particle Mixing in a Two-Dimensional Fluidized Bed Using a CFD-DEM Model

2013 ◽  
Vol 467 ◽  
pp. 367-373
Author(s):  
Sumol Sae Heng Pisitsungkakarn
Keyword(s):  
Fluidized Bed ◽  
Distinct Element ◽  
Two Dimensional ◽  
Mixing Index ◽  
Minimum Fluidization Velocity ◽  
Fluidization Velocity ◽  
Particle Mixing ◽  
Minimum Fluidization ◽  
Superficial Gas Velocity ◽  
Dem Model

Fluidized beds are widely used in many industries since they are effective in mixing process. The distinct element method (DEM) has recently received more attention for investigating the phenomena of multiphase flow because the technique is effective in gathering detailed information on the complex phenomena without physically disturbing the flows. A CFD-DEM model has been developed for calculating the minimum fluidization velocity and particle mixing in a two-dimensional fluidized bed. In this research, the inlet area on the particle mixing was investigated. From the result, it was indicated that the developed CFD-DEM model was performed adequately in predicting the phenomena in a two dimensional fluidized bed. The minimum fluidization velocity predicted by the developed model agreed well with the theory and correlation of Grace. Based on Lacey mixing index, it was found that the mixing index increased with an increase in time and superficial gas velocity. In addition, the inlet area of 20% gave a good mixing.

scholarly journals Experimental Investigation of Two-Phase Flow Patterns in a Vertical to Horizontal Bend Pipe Using Wire-Mesh Sensor

2021 ◽  
Vol 71 (12) ◽  
pp. 18-33
Author(s):  
Lokman A. Abdulkareem ◽  
Veyan A. Musa ◽  
Raid A. Mahmood ◽  
Ezideen A. Hasso
Keyword(s):  
Flow Pattern ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Flow Rates ◽  
Tomographic Images ◽  
High Range

The air-water two-phase flow plays an important role in many applications of industry fields. Usually, a 90-degree bend is used to connect pipes for changing the direction of flow which influences the two-phase flow pattern. In this paper, the effect of 90-degree bend under different ranges of gas and liquid superficial velocities on the two-phase flow patterns in the horizontal pipe located after the bend was experimentally investigated, and then results were presented and compared in a two-phase flow pattern map. Also, tomographic images and probability density functions were used to capture the cross-section void fraction and its distribution for the two-phase flow patterns. The results revealed that at low liquid and gas flow rates, a stratified-wavy flow pattern was observed as a dominant flow pattern. While the wavy-annular and semiannular flow patterns were observed at a high range of gas flow rates in the horizontal pipe. The results also showed that at the high range of liquid flow rate, bubbly, plug, slug, stratified-wavy, and wavy-annular flow patterns were observed in the horizontal pipe when the gas flow increased. The tomographic images and probability density functions gave good agreement with the experimental observations and results.

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