Flow and Deposition Characteristics Following Chokes for Pressurized CO2 Pipelines

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Lin Teng ◽  
Yuxing Li ◽  
Hui Han ◽  
Pengfei Zhao ◽  
Datong Zhang
Keyword(s):  
Particle Size ◽  
Flow Velocity ◽  
Particle Deposition ◽  
Transport Model ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Stokes Number ◽  
Sudden Expansion ◽  
Tracking Model ◽  
Good Agreement

The relieving system using the choke valve is applied to control the pressure in CO2 pipeline. However, the temperature of fluid would drop rapidly because of Joule–Thomson cooling (JTC), which may cause solid CO2 form and block the pipe. A three-dimensional (3D) computational fluid dynamic (CFD) model considering the phase transition and turbulence was developed to predict the fluid-particle flow and deposition characteristics. The Lagrangian method, Reynold's stress transport model (RSM) for turbulence, and stochastic tracking model (STM) were used. The results show that the model predictions were in good agreement with the experimental data published. The effects of particle size, flow velocity, and pipeline diameter were analyzed. It was found that the increase of the flow velocity would cause the decrease of particle deposition ratio and there existed the critical particle size that causes the deposition ratio maximum. It also presents the four types of particle motions corresponding to the four deposition regions. Moreover, the sudden expansion region is the easiest to be blocked by the particles. In addition, the Stokes number had an effect on the deposition ratio and it was recommended for Stokes number to avoid 3–8 St.

Numerical Investigation of Deposition Characteristics of Solid CO2 During Choked Flow for CO2 Pipelines

2016 ◽  
Author(s):  
Lin Teng ◽  
Yuxing Li ◽  
Hui Han ◽  
Pengfei Zhao ◽  
Datong Zhang
Keyword(s):  
Particle Size ◽  
Flow Velocity ◽  
Particle Deposition ◽  
Transport Model ◽  
Fluid Dynamic ◽  
Flow Characteristics ◽  
Stokes Number ◽  
Sudden Expansion ◽  
Choked Flow ◽  
Tracking Model

Choke valves are applied to control the pressure in CO2 pipeline. However, the temperature of fluid would drop rapidly because of Joule-Thomson cooling (JTC), which may cause solid CO2 generate and block the pipe. In this work, a three-dimensional Computational Fluid Dynamic (CFD) model, using the Lagrangian method, Reynold’s Stress Transport model (RSM) for turbulence and stochastic tracking model (STM) for particle trajectory, was developed to predict the gas-solid CO2 flow and deposition characteristics downstream pipeline. The model predictions were in good agreement with the experimental data published in the literature. The effects of particle size, flow velocity and pipeline diameter on the fluid-particle flow characteristics were examined. Results showed that the increase in the flow velocity would cause a decrease in particle deposition ratio and there existed the critical particle size that caused the deposition ratio maximum for each velocity. The paper also presents the effects of particle motion on different deposition regions. Moreover, the main deposition region (the sudden expansion region) is the easy to be blocked by the particles. With the increase in pipeline diameter, the particle deposition ratio was decreasing. In addition, it was recommended for Stokes number to avoid 3-8 St.

scholarly journals A Numerical Study of the Effect of Particle Size on Particle Deposition on Turbine Vanes and Blades

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110178
Author(s):  
Zhengang Liu ◽  
Weinan Diao ◽  
Zhenxia Liu ◽  
Fei Zhang
Keyword(s):  
Particle Size ◽  
Particle Deposition ◽  
Numerical Study ◽  
Stokes Number ◽  
Capture Efficiency ◽  
Particle Capture ◽  
Factors Affecting ◽  
Pressure Surface ◽  
Deposition Area ◽  
Turbine Vanes

Particle deposition could decrease the aerodynamic performance and cooling efficiency of turbine vanes and blades. The particle motion in the flow and its temperature are two important factors affecting its deposition. The size of the particle influences both its motion and temperature. In this study, the motion of particles with the sizes from 1 to 20 μm in the first stage of a turbine are firstly numerically simulated with the steady method, then the particle deposition on the vanes and blades are numerically simulated with the unsteady method based on the critical viscosity model. It is discovered that the particle deposition on vanes mainly formed near the leading and trailing edge on the pressure surface, and the deposition area expands slowly to the whole pressure surface with the particle size increasing. For the particle deposition on blades, the deposition area moves from the entire pressure surface toward the tip with the particle size increasing due to the effect of rotation. For vanes, the particle capture efficiency increases with the particle size increasing since Stokes number and temperature of the particle both increase with its size. For blades, the particle capture efficiency increases firstly and then decreases with the particle size increasing.

Optimization of fluid characteristics in the main nozzle of an air-jet loom

2021 ◽  
pp. 004051752110395
Author(s):  
Xinlei Huang ◽  
Lee Michael Clemon ◽  
Mohammad Saidul Islam ◽  
Suvash C. Saha
Keyword(s):  
Fluid Dynamic ◽  
Three Dimensional ◽  
Sudden Expansion ◽  
Dynamic Features ◽  
Original Design ◽  
Flow Models ◽  
Air Jet ◽  
Acceleration Tube ◽  
Air Jet Loom ◽  
Fluid Characteristics

As part of the propulsion system, the fluid dynamic features of the main nozzle can immediately affect the stability and efficiency of an air-jet loom. This study aims to optimize the fluid characteristics in the main nozzle of an air-jet loom. To investigate ways of weakening the effect of airflow congestion and backflow phenomenon occurring in the sudden expansion region, the computational fluid dynamics method is employed. Three-dimensional turbulence flow models for a regular main nozzle and 12 prototypes with different nozzle core tip geometry are built, simulated, and analyzed to get the optimum performance. Furthermore, a set of modified equations that consider the direction of airflow are proposed for better estimation of the friction force applied by the nozzle. The result shows that the nozzle core tip's geometry has a significant influence on the internal airflow, affecting the acceleration tube airflow velocity, turbulence intensity, and backflow strength of the sudden expansion region, and other critical fluid characteristics as well. Several proposed models have succeeded in reducing the backflow and outperforming the original design in many different aspects. Models A-60 and C-P, in particular, manage to increase the propulsion force by 37.6% and 20.2% in the acceleration tube while reducing the maximum backflow by 57.1% and 52.2%, respectively. These simulation results can provide invaluable information for the future optimization of the main nozzle.

scholarly journals Prediction and measurement of the aerodynamic performance of a wind turbine

2018 ◽  
Vol 240 ◽  
pp. 04001
Author(s):  
Ali Cemal Benim ◽  
Michael Diederich ◽  
Fethi Gül
Keyword(s):  
Wind Turbine ◽  
Transport Model ◽  
Three Dimensional ◽  
Detached Eddy Simulation ◽  
Simulation Framework ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Shear Stress Transport Model ◽  
Flow Turbulence ◽  
Good Agreement

Aerodynamic behavior of a small wind turbine is analyzed, both experimentally and numerically. Mainly, an unsteady three-dimensional formulation is adopted, where the flow turbulence is modelled by an Improved Delayed Detached Eddy Simulation framework, using the four-equation transitional Shear Stress Transport model, as the turbulence model. A quite good agreement between the measurements and calculations is observed.

scholarly journals Assimilation of TES CO into a global CTM: first results

2006 ◽  
Vol 6 (6) ◽  
pp. 11727-11743 ◽  
Author(s):  
N. A. D. Richards ◽  
Q. Li ◽  
K. W. Bowman ◽  
J. R. Worden ◽  
S. S. Kulawik ◽  
...  
Keyword(s):  
Transport Model ◽  
Model Simulation ◽  
Three Dimensional ◽  
Model Bias ◽  
Upper Troposphere ◽  
First Results ◽  
Assimilation Scheme ◽  
Co Observations ◽  
Good Agreement

Abstract. We present results from the first assimilation of carbon monoxide (CO) observations from the Tropospheric Emission Spectrometer (TES) into a global three-dimensional (3-D) chemistry and transport model (CTM). A sequential sub-optimal Kalman filter assimilation scheme (Khattatov et al., 2000) was applied to assimilate TES CO profiles during November 2004 into the GEOS-Chem global 3-D CTM. The assimilation results were compared with MOPITT and MOZAIC observations. The assimilation significantly improves model simulation of CO in the middle to upper troposphere, where the MOPITT versus model bias was reduced by up to two-thirds. Assimilation results show higher levels of CO in the southern tropics, consistent with MOPITT observations. We find good agreement between the TES assimilated model estimates of CO and in situ measurements from the MOZAIC program, which shows a negative bias of up to 10 ppbv in middle and upper tropospheric TES CO. The results demonstrate how assimilation can be used for non-coincident validation of TES CO profile retrievals.

scholarly journals Computational Simulation of Deposition in a Cooled High-Pressure Turbine Stage With Hot Streaks

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Robin Prenter ◽  
Ali Ameri ◽  
Jeffrey P. Bons
Keyword(s):  
High Pressure ◽  
Particle Deposition ◽  
Particle Temperature ◽  
Computational Simulation ◽  
Stokes Number ◽  
Navier Stokes ◽  
Inlet Temperature ◽  
Turbine Stage ◽  
High Pressure Turbine ◽  
Tracking Model

Ash particle deposition in a high-pressure turbine stage was numerically investigated using steady Reynolds-averaged Navier-Stokes (RANS) and unsteady Reynolds-averaged Navie-Stokes (URANS) methods. An inlet temperature profile consisting of Gaussian nonuniformities (hot streaks) was imposed on the vanes, with vane cooling simulated using a constant vane wall temperature. The steady case utilized a mixing plane at the vane–rotor interface, while a sliding mesh was used for the unsteady case. Corrected speed and mass flow were matched to an experiment involving the same geometry, so that the flow solution could be validated against measurements. Particles ranging from 1 to 65 μm were introduced into the vane domain, and tracked using an Eulerian–Lagrangian tracking model. A novel particle rebound and deposition model was employed to determine particles' stick/bounce behavior upon impact with a surface. Predicted impact and capture distributions for different diameters were compared between the steady and unsteady methods, highlighting effects from the circumferential averaging of the mixing plane. The mixing plane simulation was found to generally under predict impact and capture efficiencies compared with the unsteady calculation, as well as under predict particle temperature upon impact with the blade surface. Quantitative impact and capture efficiency trends with the Stokes number are discussed for both the vane and blade, with companion qualitative distributions for the different Stokes regimes.

scholarly journals Ultra-violet absorption cross sections of isotopically substituted nitrous oxide species: <sup>14</sup>N<sup>14</sup>NO, <sup>15</sup>N<sup>14</sup>NO, <sup>14</sup>N<sup>15</sup>NO and <sup>15</sup>N<sup>15</sup>NO

2004 ◽  
Vol 4 (3) ◽  
pp. 2333-2378
Author(s):  
P. von Hessberg ◽  
J. Kaiser ◽  
M. B. Enghoff ◽  
C. A. McLinden ◽  
S. L. Sorensen ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Cross Sections ◽  
Transport Model ◽  
Three Dimensional ◽  
Isotopic Fractionation ◽  
Ultra Violet ◽  
Field Studies ◽  
Chemical Transport Model ◽  
Uv Absorption Spectroscopy ◽  
Good Agreement

Abstract. The isotopically substituted nitrous oxide species 14N14NO, 15N14NO, 14N15NO and 15N15NO were investigated by ultra-violet (UV) absorption spectroscopy. High precision cross sections were obtained for the wavelength range 181 to 218 nm at temperatures of 233 and 283 K. These data are used to calculate photolytic isotopic fractionation constants as a function of wavelength. The fractionation constants were used in a three-dimensional chemical transport model in order to simulate the actual fractionation of N2O in the stratosphere, and the results were found to be in good agreement with field studies.

scholarly journals <i>HydrothermalFoam</i> v1.0: a 3-D hydrothermal transport model for natural submarine hydrothermal systems

2020 ◽  
Vol 13 (12) ◽  
pp. 6547-6565
Author(s):  
Zhikui Guo ◽  
Lars Rüpke ◽  
Chunhui Tao
Keyword(s):  
Transport Model ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Pure Water ◽  
Three Dimensional ◽  
Hydrothermal Systems ◽  
Dynamic Simulations ◽  
Flow Models ◽  
Wide Range ◽  
Submarine Hydrothermal Systems

Abstract. Herein, we introduce HydrothermalFoam, a three-dimensional hydro-thermo-transport model designed to resolve fluid flow within submarine hydrothermal circulation systems. HydrothermalFoam has been developed on the OpenFOAM platform, which is a finite-volume-based C++ toolbox for fluid-dynamic simulations and for developing customized numerical models that provides access to state-of-the-art parallelized solvers and to a wide range of pre- and post-processing tools. We have implemented a porous media Darcy flow model with associated boundary conditions designed to facilitate numerical simulations of submarine hydrothermal systems. The current implementation is valid for single-phase fluid states and uses a pure-water equation of state (IAPWS-97). We here present the model formulation; OpenFOAM implementation details; and a sequence of 1-D, 2-D, and 3-D benchmark tests. The source code repository further includes a number of tutorials that can be used as starting points for building specialized hydrothermal flow models. The model is published under the GNU General Public License v3.0.

scholarly journals Study and Analysis on the Influence Degree of Particle Settlement Factors in Pipe Transportation of Backfill Slurry

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1780
Author(s):  
Chonghao Wang ◽  
Deqing Gan
Keyword(s):  
Particle Size ◽  
Flow Velocity ◽  
Sedimentation Rate ◽  
Transport Model ◽  
Mining Area ◽  
Particle Sedimentation ◽  
Slurry Concentration ◽  
Proposed Model ◽  
Influence Degree ◽  
Tracking Module

In this study, we developed a pipeline transport model to investigate the influence of particle sedimentation factors on slurry transportation through pipelines. The particle tracking module of the software was used to simulate the transport process, and the influences on the sedimentation rate were analyzed considering the slurry concentration, particle size, and flow velocity. The established model exhibited small calculation errors. In addition, the results revealed that the proposed model is reliable for calculating the degree of influence of various factors on particle sedimentation. The effect of the particle sedimentation rate on the pipeline slurry was explored considering the particle size, slurry concentration, and flow velocity. The sedimentation rate was positively related to particle size and adversely related to the slurry concentration and flow velocity. Indeed, study on the sedimentation rate requires considering a reasonable range of particle sizes, preparing a slurry with an appropriate concentration, and adjusting an appropriate flow velocity. Numerical simulations were performed using the filling data as the background for a sample mining area. The experimental results showed optimal slurry concentration and particle size of 60% and 25.25 µm, respectively.

scholarly journals <i>HydrothermalFoam</i> v1.0: a 3-D hydro-thermo-transport model for natural submarine hydrothermal systems

2020 ◽  
Author(s):  
Zhikui Guo ◽  
Lars Rüpke ◽  
Chunhui Tao
Keyword(s):  
Transport Model ◽  
Numerical Models ◽  
Fluid Dynamic ◽  
Pure Water ◽  
Three Dimensional ◽  
Hydrothermal Systems ◽  
Dynamic Simulations ◽  
Flow Models ◽  
Wide Range ◽  
Submarine Hydrothermal Systems

Abstract. Herein, we introduce HydrothermalFoam, a three dimensional hydro-thermo-transport model designed to resolve fluid flow within submarine hydrothermal circulation systems. HydrothermalFoam has been developed on the OpenFOAM platform, which is a Finite Volume based C++ toolbox for fluid-dynamic simulations and for developing customized numerical models that provides access to state-of-the-art parallelized solvers and to a wide range of pre- and post-processing tools. We have implemented a porous media Darcy-flow model with associated boundary conditions designed to facilitate numerical simulations of submarine hydrothermal systems. The current implementation is valid for single-phase fluid states and uses a pure water equation-of-state (IAPWS-97). We here present the model formulation, OpenFOAM implementation details, and a sequence of 1-D, 2-D and 3-D benchmark tests. The source code repository further includes a number of tutorials that can be used as starting points for building specialized hydrothermal flow models. The model is published under the GNU General Public License v3.0.

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