A numerical model for gas flow and droplet motion in wave-plate mist eliminators with drainage channels

Calcium oxide/Calcium hydroxide can be utilized as a reaction system for thermochemical heat storage. It features a high storage capacity, is cheap, and does not involve major environmental concerns. Operationally, different fixed-bed reactor concepts can be distinguished; direct reactor are characterized by gas flow through the reactive bulk material, while in indirect reactors, the heat-carrying gas flow is separated from the bulk material. This study puts a focus on the indirectly operated fixed-bed reactor setup. The fluxes of the reaction fluid and the heat-carrying flow are decoupled in order to overcome limitations due to heat conduction in the reactive bulk material. The fixed bed represents a porous medium where Darcy-type flow conditions can be assumed. Here, a numerical model for such a reactor concept is presented, which has been implemented in the software DuMux. An attempt to calibrate and validate it with experimental results from the literature is discussed in detail. This allows for the identification of a deficient insulation of the experimental setup. Accordingly, heat-loss mechanisms are included in the model. However, it can be shown that heat losses alone are not sufficient to explain the experimental results. It is evident that another effect plays a role here. Using Bayesian inference, this effect is identified as the reaction rate decreasing with progressing conversion of reactive material. The calibrated model reveals that more heat is lost over the reactor surface than transported in the heat transfer channel, which causes a considerable speed-up of the discharge reaction. An observed deceleration of the reaction rate at progressed conversion is attributed to the presence of agglomerates of the bulk material in the fixed bed. This retardation is represented phenomenologically by mofifying the reaction kinetics. After the calibration, the model is validated with a second set of experimental results. To speed up the calculations for the calibration, the numerical model is replaced by a surrogate model based on Polynomial Chaos Expansion and Principal Component Analysis.

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A Numerical Model Coupling Reservoir and Horizontal Well-Flow Dynamics: Transient Behavior of Single-Phase Liquid and Gas Flow

SPE Journal ◽

10.2118/77096-pa ◽

2002 ◽

Vol 7 (01) ◽

pp. 70-77 ◽

Cited By ~ 2

Author(s):

Ronaldo Vicente ◽

Cem Sarica ◽

Turgay Ertekin

Keyword(s):

Numerical Model ◽

Gas Flow ◽

Horizontal Well ◽

Single Phase ◽

Transient Behavior ◽

Flow Dynamics ◽

Model Coupling ◽

Phase Liquid

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A Numerical Model Coupling Reservoir and Horizontal Well Flow Dynamics: Transient Behavior of Single-Phase Liquid and Gas Flow

10.2118/65508-ms ◽

2000 ◽

Cited By ~ 1

Author(s):

R. Vicente ◽

C. Sarica ◽

T. Ertekin

Keyword(s):

Numerical Model ◽

Gas Flow ◽

Horizontal Well ◽

Single Phase ◽

Transient Behavior ◽

Flow Dynamics ◽

Model Coupling ◽

Phase Liquid

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Simulation of the Performance of the Venturi Scrubber for an Advanced Reactor Containment Venting Conditions

Journal of Nuclear Engineering and Radiation Science ◽

10.1115/1.4044845 ◽

2019 ◽

Vol 6 (1) ◽

Author(s):

Goel Paridhi ◽

K. Nayak Arun

Keyword(s):

Numerical Model ◽

Pressure Drop ◽

Gas Flow ◽

Pressure Profile ◽

Absorption Efficiency ◽

Severe Accident ◽

Mitigation Measures ◽

Liquid Loading ◽

Venturi Scrubber ◽

Iodine Absorption

Abstract Post Fukushima, nuclear plants are being retrofitted with severe accident mitigation measures. For attaining depressurization of the containment and mitigate the consequences of the release of the radioactivity to the environment during a severe accident condition, filtered containment venting systems (FCVS) are proposed to be installed in existing reactors and being designed for advanced reactors. The design of FCVS is particular to the reactor type. The FVCS configuration considered in this paper comprises of a manifold of venturi scrubber enclosed in a scrubber tank along with metal fiber filter and demister for an advanced Indian reactor. This study focuses on the assessment of the design of the venturi scrubber for the reactor conditions at which venting is carried out through a numerical model. The numerical model is first validated with experiments performed for prototypic conditions. The predicted pressure drop and the iodine absorption efficiency were found to be in good match with the experimental measurements. Subsequently, the model is implemented for predicting the hydrodynamics, i.e., pressure drop, droplet sizes and distribution, and iodine absorption for prototypic conditions. The hydrodynamics, i.e., pressure profile in the venturi scrubber showed a decrease in the converging section and in the throat section. The diverging section showed decrease in recovery of pressure with the decrease in gas flow because of the increased liquid loading to the scrubber. The iodine absorption efficiency showed a value of 92% for high gas velocity which decreased to 68% for the lowest gas flow rate.

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Further Development and Studies of Gas Methods in Matrix Diffusion

MRS Proceedings ◽

10.1557/proc-333-821 ◽

1993 ◽

Vol 333 ◽

Cited By ~ 2

Author(s):

Kari Hartikainen ◽

K. Väätäinen ◽

A. Hautojärvi ◽

J. Timonen

Keyword(s):

Porous Media ◽

Numerical Model ◽

Water Flow ◽

Present Status ◽

Gas Flow ◽

Hydrodynamic Dispersion ◽

Matrix Diffusion ◽

Flow Experiment ◽

Further Development ◽

Flow Experiments

ABSTRACTThe present status of the recently introduced gas method equipment for migration studies of fractured and porous media is briefly reviewed together with advances in the experimental techniques. The conditions under which matrix diffusion can be observed in both gas flow and water flow experiments are discussed in some detail. Results for a gas flow experiment are shown, and explained with a numerical model which incorporates the effects of hydrodynamic dispersion and matrix diffusion. The necessary parameters for a corresponding water flow experiment are also briefly discussed.

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Numerical investigations on particle separation in dynamic separators

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-10-2018-0567 ◽

2019 ◽

Vol 30 (4) ◽

pp. 1677-1688 ◽

Cited By ~ 1

Author(s):

Arun Appadurai ◽

Vasudevan Raghavan

Keyword(s):

Numerical Model ◽

Gas Flow ◽

Separation Efficiency ◽

Numerical Models ◽

Particle Separation ◽

Numerical Results ◽

Particle Collision ◽

Content Type ◽

Numerical Predictions ◽

Eulerian Formulation

Purpose Dynamic separator is an equipment having a rotor and static vanes and is used to separate solids from gas-solids flow based on size. Particle separation in a dynamic separator happens due to complex interchanges between multiple forces exerted in the separation zone. Currently, there is only limited knowledge concerning the working principles of separation. This paper aims to systematically study a dynamic separator using numerical models to get insights into particle separation. Design/methodology/approach The Lagrangian–Eulerian formulation is used to simulate gas-solid flow. Multiple frames of reference using stage interpolation are used to account for rotation. Periodic symmetry in the equipment is exploited to create a simplified numerical model. The predictions from the numerical model are compared against available experimental data. Findings The numerical results indicate that only when particle collision is included, the separation efficiency trend from the experiment is matched by numerical predictions. Further, it is shown that at the same range of rotor speeds where numerical results predict increased separation efficiency, the solid pressure due to particle collision also reaches its maximum value. The gas flow and particle behavior in the separator are explained in detail. Originality/value The importance of particle collision in separation is interesting because traditionally, particle separation is assumed to be influenced by three forces, namely, centrifugal force, drag force and gravity. The numerical results, however, point to the contribution by particle collision, in addition to the above three forces.

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Analytical and Numerical Simulation of Asymmetric Converging Flow of Gas under Drill Bits in Reverse Circulation Gas Drilling

Journal of Energy Resources Technology ◽

10.1115/1.4051551 ◽

2021 ◽

pp. 1-11

Author(s):

Xu Yang ◽

Boyun Guo ◽

Tamaralayefa Timiyan

Keyword(s):

Numerical Model ◽

Analytical Model ◽

Gas Flow ◽

Relative Difference ◽

Structure Design ◽

Drill Bit ◽

Drill Cuttings ◽

Gas Drilling ◽

Reverse Circulation ◽

Converging Flow

Abstract Reverse circulation gas drilling has been considered to solve engineering problems such as formation water influx, wellbore instability, and excess gas requirement in gas drilling. The performance of reverse circulation gas drilling depends to a large extent on the structure design of drill bit. An analytical model and a numerical model were developed in this study to simulate the asymmetric converging flow of gas under drill bit for reverse circulation gas drilling. The two models were compared and applied to the evaluation of a drill bit structure design for bottom hole cleaning capacity of gas flow. It was found that the pressure, velocity, and specific kinetic energy given by the analytical model are slightly lower than that given by the numerical model. The relative difference between the gas flow rates given by the analytical model and the numerical model is less than 5%. For the drill bit structure design considered in this study, the gas flow energy between the short blades is much higher than that between the long blades. A gas injection rate of 10 m3/min (360 ft3/min) is expected to clean the drill cuttings between the short blades, while a gas flow rate of 28 m3/min (990 ft3/min) is required to clean the drill cuttings between the long blades. Although the numerical model gives more accurate result than the analytical model in predicting hydraulics parameters, the analytical model is recommended for evaluating drill bit structure design because of its simplicity and conservativeness.

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A 3D Numerical Investigation on Droplets Distribution in a Wave-Plate Separator

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.842.522 ◽

2013 ◽

Vol 842 ◽

pp. 522-529

Author(s):

Yong Lei Qu ◽

Shi Bu ◽

Bo Wan

Keyword(s):

Gas Flow ◽

Three Dimensional ◽

Flow Simulation ◽

Geometrical Model ◽

Turbulent Dispersion ◽

Liquid Loading ◽

Wave Plate ◽

Gas Liquid Flow ◽

Set Up ◽

Plate Separator

The gas-liquid flow in a wave-plate separator is extremely complex due to its three-dimensional characteristic. Numerical simulation accomplished by former investigators using two-dimensional model may be appropriate for the iteration of pressure drop, but they were far from accurate in prediction of removal efficiency. To fill the gap, a three dimensional geometrical model of wave-plate separator is set up in this paper, RNG k-ε model is employed to compute the gas phase flow field, and the droplet trajectories were predicted applying the Lagrangian method. The turbulent dispersion of droplets were simulated by discrete random walk model. Using the assumption of a constant liquid loading of gas flow, simulation were accomplished for six different inlet velocities and two different droplet sizes. The influence pattern of gravity together with gas velocity on droplets distribution and the overall removal efficiencies were obtained.

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Numerical Modeling of Equal and Differentiated Gas Injection in Ladles: Effect on Mixing Time and Slag Eye

Processes ◽

10.3390/pr8080917 ◽

2020 ◽

Vol 8 (8) ◽

pp. 917

Author(s):

Luis E. Jardón-Pérez ◽

Carlos González-Rivera ◽

Marco A. Ramirez-Argaez ◽

Abhishek Dutta

Keyword(s):

Numerical Modeling ◽

Numerical Model ◽

Physical Model ◽

Flow Rate ◽

Gas Flow ◽

Mixing Time ◽

Gas Injection ◽

Steel Slag ◽

Gas Flow Rate ◽

Slag Thickness

Ladle refining plays a crucial role in the steelmaking process, in which a gas stream is bubbled through molten steel to improve the rate of removal of impurities and enhance the transport phenomena that occur in a metallurgical reactor. In this study, the effect of dual gas injection using equal (50%:50%) and differentiated (75%:25%) flows was studied through numerical modeling, using computational fluid dynamics (CFD). The effect of gas flow rate and slag thickness on mixing time and slag eye area were studied numerically and compared with the physical model. The numerical model agrees with the physical model, showing that for optimal performance the ladle must be operated using differentiated flows. Although the numerical model can predict well the hydrodynamic behavior (velocity and turbulent kinetic energy) of the ladle, there is a deviation from the experimental mixing time when using both equal and differentiated gas injection at a high gas flow rate and a high slag thickness. This is probably due to the insufficient capture of the velocity field near the water–oil (steel–slag) interface and slag emulsification by the numerical model, as well as the complicated nature of correctly simulating the interaction between both gas plumes.

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