Modelling post-discharge nitriding and nitrocarburising

2004 ◽  
Vol 120 ◽  
pp. 239-247
Author(s):  
T. Belmonte ◽  
C. Jaoul ◽  
H. Michel
Keyword(s):  
Steady State ◽  
Ternary System ◽  
Gas Phase ◽  
Gas Flow ◽  
State Of The Art ◽  
Active Species ◽  
Surface Phenomena ◽  
Post Discharge ◽  
Two Phase ◽  
Adsorption Surface

In this paper, the state of the art in the modelling of nitriding and nitrocarburising using late post-discharge processes is described. In a first part, interstitial diffusion in ternary system is treated. The problem of the diffusion in two-phase domains is evoked. The chemical pathways in N2-H2 and N2-CH4 post-discharges creating active species are next presented to try to identify the precursors responsible for the transport of nitrogen and carbon to the surface of the solid. Finally, attention is paid to the coupling between the gas phase and the solid. Two different approaches are proposed, either by considering a steady state or a transient gas flow. The latter requires to introduce a sequence of surface phenomena (adsorption, surface diffusion, recombination, dissolution…) that provides a rigorous way to couple processes in the gas phase and in the solid.

Experimental, Numerical, and Statistical Investigation of Two Phase Flow in a Cylindrical Perforation Tunnel

2021 ◽  
Author(s):  
Ekhwaiter Abobaker ◽  
Abadelhalim Elsanoose ◽  
Mohammad Azizur Rahman ◽  
Faisal Khan ◽  
Amer Aborig ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Statistical Analysis ◽  
Flow Rate ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Gas Flow Rate ◽  
Two Phase ◽  
Flow Through

Abstract Perforation is the final stage in well completion that helps to connect reservoir formations to wellbores during hydrocarbon production. The drilling perforation technique maximizes the reservoir productivity index by minimizing damage. This can be best accomplished by attaining a better understanding of fluid flows that occur in the near-wellbore region during oil and gas operations. The present work aims to enhance oil recovery by modelling a two-phase flow through the near-wellbore region, thereby expanding industry knowledge about well performance. An experimental procedure was conducted to investigate the behavior of two-phase flow through a cylindrical perforation tunnel. Statistical analysis was coupled with numerical simulation to expand the investigation of fluid flow in the near-wellbore region that cannot be obtained experimentally. The statistical analysis investigated the effect of several parameters, including the liquid and gas flow rate, liquid viscosity, permeability, and porosity, on the injection build-up pressure and the time needed to reach a steady-state flow condition. Design-Expert® Design of Experiments (DoE) software was used to determine the numerical simulation runs using the ANOVA analysis with a Box-Behnken Design (BBD) model and ANSYS-FLUENT was used to analyses the numerical simulation of the porous media tunnel by applying the volume of fluid method (VOF). The experimental data were validated to the numerical results, and the comparison of results was in good agreement. The numerical and statistical analysis demonstrated each investigated parameter’s effect. The permeability, flow rate, and viscosity of the liquid significantly affect the injection pressure build-up profile, and porosity and gas flow rate substantially affect the time required to attain steady-state conditions. In addition, two correlations obtained from the statistical analysis can be used to predict the injection build-up pressure and the required time to reach steady state for different scenarios. This work will contribute to the clarification and understanding of the behavior of multiphase flow in the near-wellbore region.

Quantitative Visualization of Two-Phase Flow in the Head of Plate-Fin Heat Exchanger

2014 ◽  
Author(s):  
Xincheng Tu ◽  
Sung-jun Kim ◽  
Hyoung-Bum Kim
Keyword(s):  
Heat Exchanger ◽  
Natural Gas ◽  
Gas Phase ◽  
Gas Flow ◽  
Imaging Techniques ◽  
Flow Distribution ◽  
Ccd Cameras ◽  
Two Phase ◽  
Piv Method ◽  
Quantitative Visualization

In this study, we experimentally investigated the distribution of liquid and gas flow in the head of plate-fin heat exchanger. The scale-downed model of proto-type heat exchanger was used and the air and water replaced the natural gas and liquefied natural gas. Two CCD cameras were synchronized with laser to capture the image of liquid-gas flow in the head. Advanced imaging techniques such as LIF, PIV method were used to measure the velocity field of liquid and gas flow simultaneously. The characteristics of momentum transfer process between liquid phase and gas phase are presented in the terms of ensemble averaged result. The effect of liquid mass fraction on the flow distribution was investigated. Then, we quantified the flow distribution of liquid and gas phase for different inlet nozzle configurations.

scholarly journals Numerical Simulation of Gas-Particle Two-Phase Flow in a Nozzle with DG Method

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Duan Maochang ◽  
Yu Xijun ◽  
Chen Dawei ◽  
Qing Fang ◽  
Zou Shijun
Keyword(s):  
Flow Field ◽  
Gas Phase ◽  
Mass Fraction ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Governing Equations ◽  
Two Phase ◽  
Dg Method ◽  
The Impact

In this paper, the discontinuous Galerkin (DG) method is applied to solve the governing equations of the dispersed two-phase flow with the two-fluid Euler/Euler approach. The resulting governing equations are simple in form and the solution process is very natural. The characteristics of the gas-particle two-phase flow in an engine nozzle are mainly analyzed, and the impacts of the particle mass fraction and particle size on the flow field and engine performance are evaluated. Because of the addition of particles, the gas flow field undergoes significant modifications. Increase in the mass fraction leads to a significant thrust loss in the gas phase, and the impact of the particles on the gas phase could be substantial. Therefore, a quantitative study of thrust loss in the nozzle due to the particle impact is made. It is found that the gas thrust in the two-phase flow is reduced, but the total thrust of the two-phase flow increases to a certain extent.

Effect of Bubble Size and Angle of Tapered Upriser Pipe on the Effectiveness of a Two Phase Lifting Pump

2009 ◽  
Author(s):  
P. Hanafizadeh ◽  
M. H. Saidi ◽  
A. Zamiri ◽  
A. Karimi
Keyword(s):  
Gas Phase ◽  
Flow Rate ◽  
Bubble Size ◽  
Gas Flow ◽  
Bubble Diameter ◽  
Design Parameters ◽  
Two Phase ◽  
Bubble Distribution ◽  
Improved Performance ◽  
Different Diameters

Two phase lifting pumps are devices with the ability of lifting liquid phase by injecting the gas phase. Parameters which affect the performance of these pumps are divided into two groups. The first group contains design parameters such as diameter of the pipe, tapering angle of the upriser pipe and the submergence ratio which is the ratio of immersed length to the total length of the upriser. The second group includes operating parameters, such as the gas flow rate, bubble diameter, bubble distribution and inlet gas pressure. In this research, the performance of two phase lifting pump is investigated numerically for different submergence ratios and different diameter of the upriser pipe. For this purpose the two phase pump with a riser length of 914 mm and different diameters (6, 8 and 10 mm), and seven tapering angles (0°, 0.25°, 0.5°, 1°, 1.5°, 2° and 3°) are numerically modeled and analyzed. Different submergence ratios are used, namely: 0.4, 0.6 and 0.8. The numerical results are compared with the existing experimental data in the literature showing a reasonable agreement. The results indicate that decrease in size of the bubble diameter increases mass flow rate of liquid at constant submergence ratios. The present study reports the improved performance of this pump with decrease in bubble size and increase in angle of tapered upriser pipe. Moreover, the results show that the tapered upriser pipe with 3° tapering angle gives the highest efficiency at nearly all submergence ratios. Further, the highest efficiency of the pump is shown to be at the largest submergence ratio, namely 0.8.

Compressibility Effects in the Gas Phase for Unsteady Annular Two-Phase Flow in a Microchannel

2006 ◽  
Author(s):  
Alexandru Herescu ◽  
Jeffrey S. Allen
Keyword(s):  
Shock Wave ◽  
Gas Phase ◽  
High Speed ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Flow Behavior ◽  
Flow Section ◽  
Phase Flow ◽  
Two Phase ◽  
Gas Liquid Flow

High speed microscopy experiments investigating two-phase (gas-liquid) flow behavior in capillary-scale systems, that is, systems where capillary forces are important relative to gravitational forces, have revealed a unique unsteady annular flow with periodic destabilization of the gas-liquid interface. Standing waves develop on the liquid film and grow into annular lobes similar with those observed in low-speed two-phase flow. The leading face of the lobe will decelerate and suddenly become normal to the wall of the capillary, suggesting the possibility of a shock wave in the gas phase at a downstream location from the minimum gas flow section. Visualization of the naturally occurring convergent-divergent nozzle-like structures as well as a discussion on the possibility of shock wave formation are presented.

scholarly journals Radioisotope measurements of the liquid-gas flow in the horizontal pipeline using phase method

2018 ◽  
Vol 180 ◽  
pp. 02032
Author(s):  
Robert Hanus ◽  
Marcin Zych ◽  
Marek Jaszczur ◽  
Leszek Petryka ◽  
Dariusz Świsulski
Keyword(s):  
Gas Phase ◽  
Gas Flow ◽  
Spectral Density Function ◽  
Phase Method ◽  
Two Phase ◽  
Cross Spectral Density ◽  
Flow Investigation ◽  
Phase Liquid ◽  
Gamma Absorption ◽  
Classical Cross

The paper presents application of the gamma-absorption method to a two-phase liquid-gas flow investigation in a horizontal pipeline. The water-air mixture was examined by a set of two Am-241 radioactive sources and two NaI(Tl) scintillation probes. For analysis of the electrical signals obtained from detectors the cross-spectral density function (CSDF) was applied. Results of the gas phase average velocity measurements for CSDF were compared with results obtained by application of the classical cross-correlation function (CCF). It was found that the combined uncertainties of the gas-phase velocity in the presented experiments did not exceed 1.6% for CSDF method and 5.5% for CCF.

Experimental Study on the Fluctuation Characteristics of Pressure Drop and Mass Flux of the Two-Phase Flow in Narrow Channel

2013 ◽  
Author(s):  
Deqi Chen ◽  
Qinghua Wang ◽  
Zhengang Duan ◽  
Liang-ming Pan
Keyword(s):  
Liquid Phase ◽  
Pressure Drop ◽  
Gas Phase ◽  
Flow Rate ◽  
Mass Flux ◽  
Gas Flow ◽  
Working Fluid ◽  
Phase Flow ◽  
Two Phase ◽  
Liquid Mass

In this paper the study focuses on a visual investigation on the gas-water two-phase flow in a vertical circular narrow channel with 2 mm inner diameter under atmospheric pressure. Experiments were carried out with different working conditions, including different gases as gas-phase working fluids such as nitrogen, air, carbon dioxide and argon, and the gas flow rate, Q, varied between 0 ml/s (single liquid phase flow) to 9.0 ml/s, and the liquid mass flux, G, varied between 581.3 kg/m2s to 3201.8 kg/m2s. The influence of liquid mass flux, gas flow rate as well as Eo number and Mo number (using these two non-dimensional parameters to specify the effect of gas-phase properties) on the fluctuation of pressure drop and mass flux were investigated in this study. It is found that the pressure drop increases along with increasing liquid-phase flow rate with identical other working conditions, and the corresponding flow patterns are slug flow even though the liquid-phase flow rates are different. However, the pressure drop decreases at first and then increases along with gas-phase flow rate, with constant liquid flow rate (liquid mass flux), and the corresponding flow patterns include slug flow, slug-annular flow and annular flow. Based on the experimental result, it is also found that the smaller Eo number and Mo number of the gas-phase working fluid, the smaller the fluctuations of the pressure drop and mass flux would be due to the gas-phase working fluid is different.

Two-Phase, Two-Component Critical Flow in a Venturi

1972 ◽  
Vol 94 (1) ◽  
pp. 147-151 ◽  
Author(s):  
R. V. Smith
Keyword(s):  
Gas Phase ◽  
Gas Flow ◽  
Critical Flow ◽  
Flow Conditions ◽  
Transfer Coefficients ◽  
Two Phase ◽  
One Dimensional ◽  
Flow Equations ◽  
Heat Transfer Coefficients ◽  
Wide Range

This paper reports the results of an analytical and experimental investigation whose object was to test the hypothesis that the flow of the gas phase controls critical and near critical two-phase flow for cases where the gas flow is essentially in separate streams. The results substantiate the hypothesis. The analytical results also indicate that one dimensional flow equations with reasonably accurate estimates for the droplet size and for the drag and heat transfer coefficients will adequately describe critical and near critical flow over a wide range of flow conditions.

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