A numerical study of effects of counter-current gas flow rate on local hydrodynamic characteristics of falling films over horizontal tubes

The experimental and numerical study has been conducted on the sleeve-repair welding of API 5L X65 pipeline. In order to simulate the in-service condition, the internal pressure of 45kgf/cm2 was applied using a nitrogen gas. SMAW and GTAW were applied to weld the sleeve. The macrostructure and hardness of repair welds have been examined. The finite element analysis of the multi-pass sleeve-fillet welding has been conducted to validate the experiment and investigate the effects of in-service welding conditions. The effect of gas flow rate on the hydrogen cracking was investigated. The effect of internal pressure on residual stresses and plastic strain was investigated. The allowable heat input was predicted considering the maximum temperature of inner surface of pipe and cooling rate at CGHAZ from the simulation of 1-pass sleeve-fillet welding.

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Experimental Study of the Influence of Gas Flow Rate on Hydrodynamic Characteristics of Sieve Trays and Their Effect on CO2 Absorption

Applied Sciences ◽

10.3390/app112210708 ◽

2021 ◽

Vol 11 (22) ◽

pp. 10708

Author(s):

Adel Almoslh ◽

Falah Alobaid ◽

Christian Heinze ◽

Bernd Epple

Keyword(s):

Experimental Study ◽

Pressure Drop ◽

Flow Rate ◽

Gas Flow ◽

Water System ◽

Volumetric Flow Rate ◽

Hydrodynamic Characteristics ◽

Co2 Absorption ◽

Gas Flow Rate ◽

Sieve Tray

An experimental study was conducted in the sieve tray column to investigate the influence of gas flow rate on the hydrodynamic characteristics of the sieve tray, such as total tray pressure drop, wet tray pressure drop, dry tray pressure drop, clear liquid height, liquid holdup, and froth height. The hydrodynamic characteristics of the sieve tray were investigated for the gas/water system at different gas flow rates from 12 to 24 Nm3/h and at different pressures of 0.22, 0.24, and 0.26 MPa. In this study, a simulated waste gas was used that consisted of 30% CO2 and 70% air. The inlet volumetric flow rate of the water was 0.148 m3/h. The temperature of the inlet water was 19.5 °C. The results showed that the gas flow rate has a significant effect on the hydrodynamic characteristics of the tray. The authors investigated the effect of changing these hydrodynamic characteristics on the performance of a tray column used for CO2 capture.

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Treatment of C.I Reactive Blue 160 by ozonation system

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/964/1/012030 ◽

2022 ◽

Vol 964 (1) ◽

pp. 012030

Author(s):

Pham-Hung Duong ◽

Ngoc-Han T. Huynh ◽

Yong-Soo Yoon

Keyword(s):

Flow Rate ◽

Gas Flow ◽

High Efficiency ◽

Continuous Operation ◽

Dyeing Wastewater ◽

Gas Flow Rate ◽

Batch Mode ◽

Ozonation Time ◽

Removal Efficiencies ◽

Counter Current

Abstract This study was carried out to assess the treatment ability of color, dye, and COD in the dyeing wastewater containing C.I Reactive Blue 160 by ozonation system. Both batch and continuous operating modes with concurrent and counter-current flows were investigated. The effects of the ozone gas flow rate, pH, temperature, Na2CO3 concentration, and initial dye concentration were evaluated. The decolorization, dye removal efficiencies, and mineralization ability of COD by ozonation were determined. The results indicated that ozonation had high efficiency in the treatment of dyeing wastewater containing C.I Reactive Blue 160. The treatment performance was affected by the ozone gas flow rate, pH, temperature, Na2CO3 concentration, and initial dye concentration. The removal efficiency of color, dye, and COD were 98.04%, 99.84%, and 87.31% for the treatment of 200 mg/L initial dye concentration in batch mode with 30 min ozonation time, respectively. In the continuous operation and counter-current flow, the color, dye, and COD removal efficiencies reached 97.24%, 99.76%, and 86.38% after 30 min HRT, respectively, and higher than concurrent flow. The reaction of ozone and C. I Reactive Blue 160 was the first-order reaction in both batch and continuous operation. The complete mineralization required 90 min ozonation time.

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Investigation of Multiphase Flow in Porous Media Around Perforation Tunnel Near Wellbore Region, Experimental and Numerical Study

10.1115/omae2021-62915 ◽

2021 ◽

Author(s):

Abadelhalim Elsanoose ◽

Ekhwaiter Abobaker ◽

Faisal Khan ◽

Aziz Rahman ◽

Amer Aborig

Keyword(s):

Porous Media ◽

Multiphase Flow ◽

Flow Rate ◽

Gas Flow ◽

Numerical Study ◽

Flow In Porous Media ◽

Dominant Factor ◽

Porous System ◽

Gas Flow Rate ◽

Pressure Buildup

Abstract Understanding the behavior of the multiphase flow in the porous media near the wellbore region is essential for increasing wells’ productivity and oil recovery. In this paper, an experimental and numerical study of multiphase flow in porous media near a perforation tunnel is presented. The effect of properties on the flow, such as porosity and permeability, are crucial for increasing oil and gas production. Two-phase flow through a cylindrical porous media with a perforation tunnel samples experimentally and numerically tested. Five sandstone samples were created at Memorial university labs, the sample dimensions are 30.48 cm high, 15.54 cm diameter, and a perforation tunnel has a 25.54 cm depth and 2.54cm diameter. The air and water injected into the sample radially at different flow rates, the water flow rate ranged from 1 to 3 LPM, and the air 3 to 9 LPM. The simulation carried out using ANSYS-Fluent 18.1 commercial software simulates the Volume Of Fluid method VOF coupled with the different turbulent models used to simulate the flow. The results showed that the porous media’s pressure buildup is greatly affected by the gas flow rate and its permeability. The wellbore pressure and porosity have more negligible effect on the pressure buildup profile in the porous media. The dominant factor for the breakthrough of a fluid in a core sample is the gas flow rate. Incorporating the gas flow in a porous system will reduce hydrostatic pressure loss, and less time is required to activate the breakthrough time.

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Numerical Study of Transport and Reaction Phenomena in GaN Vapor Phase Epitaxy

Heat Transfer: Volume 3 ◽

10.1115/ht2005-72337 ◽

2005 ◽

Author(s):

D. Cai ◽

L. L. Zheng

Keyword(s):

Heat Transfer ◽

Temperature Distribution ◽

Vapor Phase ◽

Flow Rate ◽

Gas Flow ◽

Numerical Study ◽

Vapor Phase Epitaxy ◽

Mixing Process ◽

Gas Flow Rate ◽

Geometric Conditions

A vapor phase epitaxy (VPE) system has been designed to grow high quality gallium nitride layers under the deposition temperature of 990°C and the pressure range of 200–800 Torr. For the better understanding of the deposition mechanism of GaN layers, a numerical model that is capable of describing multi-component fluid flow, gas/surface chemistry, conjugate heat transfer, thermal radiation, and species transport, has been developed to help in design and optimization of the epitaxy growth system. The vacuum area between heaters and reactor tube is simulated as a solid body with small thermal conductivity and totally transparent to radiative heat transfer. Simulation results were compared to the experimental data to examine the temperature distribution achieved inside the growth reactor. To optimize operating parameters, the reaction mechanism for GaN in the VPE system has been identified, and the comprehensive computational simulations have been performed to study the temperature distribution, species mixing process, ammonia decomposition process and GaN deposition rate distribution on the substrate. Parametric studies have been performed to investigate the effects of operational and geometric conditions, such as temperature, reacting/carrier gas flow rate and distance between the substrate and the nozzle, on species mixing process and GaN deposition uniformity. The relationship between gas flow rate and III/V ratio achieved on the substrate will be established.

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FORMATION OF NANOLITER BUBBLES IN MICROFLUIDIC T-JUNCTIONS

NANO ◽

10.1142/s1793292010002086 ◽

2010 ◽

Vol 05 (03) ◽

pp. 175-184 ◽

Cited By ~ 3

Author(s):

JING FAN ◽

YUXIANG ZHANG ◽

LIQIU WANG

Keyword(s):

Liquid Phase ◽

Flow Rate ◽

Formation Process ◽

Relative Velocity ◽

Gas Flow ◽

Numerical Study ◽

Bubble Formation ◽

Pressure Variation ◽

Width Ratio ◽

Gas Flow Rate

A numerical study on nanoliter bubble formation process in microfluidic T-junctions is conducted. The simulated bubble sequence agrees well with experiments. The pressure and velocity distribution in liquid phase, and streamlines of relative velocity of liquid to bubbles are obtained. We also studied pressure variation at the junction and gas flow rate for the first several bubbles, and illustrated the special impact of channel width ratio on bubble formation process. Finally, we derived the critical nondimensional gas pressure above which bubbles can be generated.

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Numerical Study on Bubble-Melt Two-Phase Flows in the Production Process of Aluminum Foams

Materials Science Forum ◽

10.4028/www.scientific.net/msf.704-705.796 ◽

2011 ◽

Vol 704-705 ◽

pp. 796-803

Author(s):

Hong Liu ◽

Mao Zhao Xie ◽

Jun Rui Shi ◽

Hong Sheng Liu

Keyword(s):

Flow Rate ◽

Gas Flow ◽

Reference Frames ◽

Numerical Study ◽

Fluid Model ◽

Bubble Diameter ◽

Functional Materials ◽

Gas Flow Rate ◽

Aluminum Foams ◽

Two Phase

Aluminum foams, as a representative of metallic foams, are a kind of very useful and promising functional materials. This paper reports progress in three-dimensional numerical simulations of gas bubble-metallic melt turbulent flows during the foaming process of aluminum foams, in which air is injected into molten aluminum composites and the melt is mechanical stirred by a pitched-blade impeller with an inclined shaft. The bubble-melt two phase flow in the tank is described with an Eulerian-Eulerian two fluid model, the impeller flow region is simulated based on the Multiple Reference Frames (MRF) method. Influences of gas flow rate, impeller rotation speed and initial bubble diameter on the characteristics of the liquid flow field and gas fraction distribution are examined. Computational results show that bubbles tend to accumulate behind the impeller blades and have an approximately uniform distribution near the top surface of the liquid. Gas holdup values are increased with increasing the impeller speed and gas flow rate and decreased with the bubble diameter.

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Absolute and convective instabilities in counter-current gas–liquid film flows

Journal of Fluid Mechanics ◽

10.1017/jfm.2014.667 ◽

2014 ◽

Vol 763 ◽

pp. 166-201 ◽

Cited By ~ 19

Author(s):

Rajagopal Vellingiri ◽

Dmitri Tseluiko ◽

Serafim Kalliadasis

Keyword(s):

Liquid Film ◽

Flow Rate ◽

Gas Flow ◽

Absolute Instability ◽

Gas Flow Rate ◽

Convective Instabilities ◽

Budget Analysis ◽

Non Local ◽

Counter Current ◽

Good Agreement

AbstractWe consider a thin liquid film flowing down an inclined plate in the presence of a counter-current turbulent gas. By making appropriate assumptions, Tseluiko & Kalliadasis (J. Fluid Mech., vol. 673, 2011, pp. 19–59) developed low-dimensional non-local models for the liquid problem, namely a long-wave (LW) model and a weighted integral-boundary-layer (WIBL) model, which incorporate the effect of the turbulent gas. By utilising these models, along with the Orr–Sommerfeld problem formulated using the full governing equations for the liquid phase and associated boundary conditions, we explore the linear stability of the gas–liquid system. In addition, we devise a generalised methodology to investigate absolute and convective instabilities in the non-local equations describing the gas–liquid flow. We observe that at low gas flow rates, the system is convectively unstable with the localised disturbances being convected downwards. As the gas flow rate is increased, the instability becomes absolute and localised disturbances spread across the whole domain. As the gas flow rate is further increased, the system again becomes convectively unstable with the localised disturbances propagating upwards. We find that the upper limit of the absolute instability region is close to the ‘flooding’ point associated with the appearance of large-amplitude standing waves, as obtained in Tseluiko & Kalliadasis (J. Fluid Mech., vol. 673, 2011, pp. 19–59), and our analysis can therefore be used to predict the onset of flooding. We also find that an increase in the angle of inclination of the channel requires an increased gas flow rate for the onset of absolute instability. We generally find good agreement between the results obtained using the full equations and the reduced models. Moreover, we find that the WIBL model generally provides better agreement with the results for the full equations than the LW model. Such an analysis is important for an understanding of the ranges of validity of the reduced model equations. In addition, a comparison of our theoretical predictions with the experiments of Zapke & Kröger (Intl J. Multiphase Flow, vol. 26, 2000, pp. 1439–1455) shows a fairly good agreement. We supplement our stability analysis with time-dependent computations of the linearised WIBL model. To provide some insight into the mechanisms of instability, we perform an energy budget analysis.

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SCIENTIFIC AND ENGINEERING PRINCIPLES OF EFFICIENT FUEL USE AND ENVIRONMENTALLY FRIENDLY GAS COMBUSTION IN STOVE PLATES. PART 1. MODERN STATE-OF-THE-ART AND DIRECTIONS FOR IMPROVEMENT THE GAS BURNING IN DOMESTIC GAS COOKERS

Energy Technologies & Resource Saving ◽

10.33070/etars.3.2017.01 ◽

2017 ◽

pp. 3-18 ◽

Cited By ~ 1

Author(s):

B.S. Soroka ◽

V.V. Horupa

Keyword(s):

Natural Gas ◽

Flow Rate ◽

Gas Flow ◽

Renewable Energy Sources ◽

Combustion Process ◽

Orifice Diameter ◽

Firing Process ◽

Gas Flow Rate ◽

Gas Combustion ◽

Gas Stoves

Natural gas NG consumption in industry and energy of Ukraine, in recent years falls down as a result of the crisis in the country’s economy, to a certain extent due to the introduction of renewable energy sources along with alternative technologies, while in the utility sector the consumption of fuel gas flow rate enhancing because of an increase the number of consumers. The natural gas is mostly using by domestic purpose for heating of premises and for cooking. These items of the gas utilization in Ukraine are already exceeding the NG consumption in industry. Cooking is proceeding directly in the living quarters, those usually do not meet the requirements of the Ukrainian norms DBN for the ventilation procedures. NG use in household gas stoves is of great importance from the standpoint of controlling the emissions of harmful components of combustion products along with maintenance the satisfactory energy efficiency characteristics of NG using. The main environment pollutants when burning the natural gas in gas stoves are including the nitrogen oxides NOx (to a greater extent — highly toxic NO2 component), carbon oxide CO, formaldehyde CH2O as well as hydrocarbons (unburned UHC and polyaromatic PAH). An overview of environmental documents to control CO and NOx emissions in comparison with the proper norms by USA, EU, Russian Federation, Australia and China, has been completed. The modern designs of the burners for gas stoves are considered along with defining the main characteristics: heat power, the natural gas flow rate, diameter of gas orifice, diameter and spacing the firing openings and other parameters. The modern physical and chemical principles of gas combustion by means of atmospheric ejection burners of gas cookers have been analyzed from the standpoints of combustion process stabilization and of ensuring the stability of flares. Among the factors of the firing process destabilization within the framework of analysis above mentioned, the following forms of unstable combustion/flame unstabilities have been considered: flashback, blow out or flame lifting, and the appearance of flame yellow tips. Bibl. 37, Fig. 11, Tab. 7.

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