Increasing Liquid Flow Rate Research Articles

Computational fluid dynamics modeling of gas bubble separation efficiency in downhole separators and vertical / inclined annulus: An experimental validation and analysis

This study presents a comprehensive investigation into gas bubble separation efficiency in a vertical downhole separator using computational fluid dynamics (CFD) modeling, which is validated with experimental data. The research aims to provide detailed insights into the separation mechanisms and the factors affecting them, such as liquid velocity, gas bubble sizes, and positions. Using an Euler-Lagrange multiphase model, the behavior of individual gas bubbles within the liquid-gas mixture was simulated. The results demonstrate that separation efficiency decreases as the liquid flow rate increases. This reduction in efficiency occurs because the increased liquid flow rate drags more bubbles within the stream, making it harder for them to separate. The separation process is primarily driven by the buoyancy force acting on the bubbles and the velocity profile of the liquid flow. Smaller bubbles, which tend to be near the casing wall, separate more efficiently, while larger bubbles are predominantly located between the second and third quarters of the annulus space. The "quarters" refer to radial divisions from the casing wall to the tubing wall, with the first quarter closest to the casing wall and the fourth quarter closest to the tubing wall. The study introduces a nonlinear regression model based on the numerical results to predict liquid slug separation efficiency. This model, validated against experimental data, accurately predicts separation efficiency and offers a robust methodology for estimating the efficiency of gravity-driven gas-liquid separators. This methodology is crucial for refining separator design and improving the operational efficiency of downhole separation systems, which are vital for enhancing the performance of pumping systems in oil and gas wells. The contributions of this study include a deeper understanding of the downhole separation process, the development of a simplified model for assessing bubble separation efficiency, and the potential application of the proposed methodology to different gas-liquid separator designs and inclination angles, thereby informing the design and operation of downhole separation systems.

Gas–liquid mass-transfer characteristics during dissolution and evolution in quasi-static and dynamic processes

This study aims to understand the comprehensive behavior of the gas–liquid flow and dissolution–evolution mass transfer. A quasi-static closed-tank experiment was designed to measure the static mass-transfer coefficients of the dissolution and evolution processes using the diffusion equation. After a detailed uncertainty analysis, a dynamic ventilated-pipe experiment with different-sized orifice plates was designed to illustrate the relationship between the hydrodynamic parameters, physical structure, and gas–liquid mass-transfer characteristics. The results showed that, as the static pressure and liquid-level height increase, both the dissolution and evolution coefficients exhibit increasing trends. However, when the physical condition reaches the initial state after pressurization and depressurization, the gas absorbed by the solution cannot completely evolve from the solution; that is, the dissolution rate is always greater than or equal to the evolution rate. For the equal-diameter pipe, as the gas flow rate increases, the concentration increment decreases slightly after reaching the peak, owing to the reduction in mass-transfer time caused by the increase in liquid flow rate. In particular, the maximal dissolved concentration, an increment of 210.9 %, occurred in the double large-orifice plate with the ventilated condition, far exceeding the maximum value in the quasi-static process. Moreover, the concentration under the layout of two small-orifice plates decreases slightly, and the larger gas content enables the solution to have more gas nuclei, making it easier to induce the gas evolution. The current study provides guidance for the gas–liquid-mixture transportation and improvement of the dissolved efficiency.

New insight and experimental study of ineffective void in hydrodynamic performance of countercurrent‐flow packing column

AbstractExtensive experimental research and hydrodynamic models have been proposed to guide the design of superior packings. However, most research has concentrated on the effective void (ε − H) of packing while ignoring the ineffective void (ε − H − HL), which causes discrepancies in hydrodynamic performance compared to actual observations. This study evaluated the hydrodynamic performance under diverse conditions considering the liquid holdup (H), pressure drop (ΔP), and gas flooding velocity (uf). A novel approach to hydrodynamic model construction is introduced by incorporating an ineffective void. The results indicate that at a constant hold‐up area, liquid flow (L) and viscosity (μ) significantly influence liquid hold up, moderated by the gas velocity in the flooding area. The pressure drop rises as the viscosity, gas flow rate, and liquid flow rate increase. Notably, a considerable pressure drop initiates flooding at the bottom of the absorber. Elevated liquid flow rates and viscosities correlate with higher ineffective void values (HL) in the packing column. At low gas flow rates, the gas flow rate marginally affects HL values. However, after the flooding point was achieved, the values of HL rapidly increased as the gas flow rate increased. Moreover, a linear relationship emerges between the liquid holdup and HL, as evidenced by the consistent variation in the liquid holdup and the F‐factor. Utilizing the ineffective void yields a more accurate fit for the experimental data, reducing the average absolute relative deviation to 10.2%, 7.4%, and 10.8%, respectively.

Modeling, Simulation, and Membrane Wetting Estimation in Gas-Liquid Contacting Processes Including Shell-Side Reaction: Biogas Upgrading Using DEA Solution.

The basic principles of a steady-state mass transfer model and the resistance-in-series film model are assessed with the aid of a series of experiments in a gas-liquid contact membrane mini-module (3 M Liqui-Cel MM-1.7 × 5.5) using an aqueous solution of diethanolamine (DEA) of 0.25 M (mol/L) for biogas upgrading. Experimental data show that CO2 removal may exceed 67% and reach 100% in combination with the highest possible recovery of CH4 when employing biogas flow rates in the range of 2.8 × 10-5 - 3.6 × 10-5 m3/s and solvent flow rates within 0.47 × 10-5 - 0.58 × 10-5 m3/s. For the experimental data set, a correlation has been developed, effectively interpolating CO2 removal with the gas and liquid flow rates. The wetting values calculated are concentrated close to each other for the same liquid flow rate without considerably depending on the gas flow rate, especially when applying the Hikita-Yun (reaction rate-shell-side correlation) compared with the Hikita-Costello pair. Furthermore, the calculated wetting diminishes with increasing liquid flow rate, a result that is consistent with previous modeling attempts and relevant literature indications. The assumption of enhanced mass transfer in the liquid-filled part of the membrane pores due to the reaction is scrutinized, leading to objectionable computational wetting values. It is shown that for a concentration of DEA equal to 0.25 M the Hatta numbers and the enhancement factors are not equal in the whole reaction path; thus, the choice of the shell-side correlation has an appreciable impact on the overall analysis, especially for the determination of the wetting values.

Experimental study on the spray characteristics of an internal-mixing gas-liquid injector

To determine the spray characteristics of internal-mixing gas-liquid injector under various operating conditions, the experimental facilities for spraying are established. By means of high-speed camera, laser particle size analyzer and PIVlab, the effects of gas and liquid flow conditions on the spray characteristics, such as position of jet impingement, spray angle, breakup length, velocity distribution and droplet size, have been investigated in detail. Experimental results demonstrated that there are two types of atomization for this injector, namely impact atomization and aerodynamic atomization. The impingement position of the liquid jets is outside of the injector exit. Alternatively, no impingement occurs between the jets. The spray angle increases with the increase of liquid flow rate, and decreases with the increase of gas flow rate. The breakup length decreases with the increase of the liquid or gas flow rate. The higher the liquid flow rate, the greater the velocity distributed along the axial and radial direction. However, the effect of gas flow rate on the velocity along the axial and radial directions acts differently at different spatial position. An increase in the liquid flow rate causes the droplet diameter to increase first and then decrease. The droplet size will decrease when the gas-liquid momentum ratio increases.

Experimental and Numerical Study of Hydraulic Characteristics and Pressurization Deterioration Mechanism of a Three-Stage Mixed-Flow Electrical Submersible Pump Under Gas-Liquid Condition

Abstract Electrical submersible pump (ESP) is extensively utilized in industrial sectors such as petroleum, chemical, and nuclear energy. However, ESPs experience pressurization deterioration due to the high gas volume fraction (GVF), resulting in the pressurization failure. In this paper, a three-stage mixed-flow ESP with closed impeller structure is detailed analysis. The interstage hydraulic characteristics and pressurization deterioration mechanism of the mixed-flow ESP are investigated at various rotational speeds and inlet conditions by combining experimental and simulation. The population balance model (PBM) and renormalization group (RNG) k − ε model are employed. As the liquid flowrate increases, the ESP experiences a “three-stage” downward trend in pressurization. It is discovered that the first booster stage has a lower inflow velocity and flow separation degree compared to the subsequent booster stages, resulting in a greater liquid-phase pressurization capacity. The gas–liquid pressurization exhibits a wave-shaped downward trend due to significant deterioration in stage-wise pressurization when the liquid flowrate is low. Once the inlet gas volume fraction (IGVF) reaches the first critical GVF, the gas aggregates on the impeller's suction surface are removed at the impeller outlet, creating an annular air mass, which creates a chaotic vortex absorbing the fluids' kinetic energy.

Comparative study of natural ester oil and mineral oil on the applicability of the immersion cooling for a battery module

The immersion cooling for lithium-ion batteries based on insulating oil has gained a great deal of interest and research, while most of them still lie in the exploratory phase with numerical and model-scale experimental efforts, and applicable cooling mediums as well as the cooling mechanisms are still inconclusive. In this paper, an oil-immersed cooling system for a battery module is designed to verify the feasibility of natural ester oil by comparing with the currently popular mineral oil. The thermal behaviors of the battery module immersed in static and dynamic insulating oils are discussed. It is found that both mineral oil and natural ester oil can efficiently decrease the battery temperature and limit the temperature difference among the batteries to less than 2 °C. For both insulating oils, the cooling effect increases with increasing liquid flow rate, but this improvement gradually weakens. With increasing Reynolds numbers, the forced convection replaces the natural convection as the dominant mechanism, especially in the natural ester oil-based system where the forced convection dominates even in the entire Re range. The comparative results demonstrate that natural ester oil can serve as a potential candidate for the battery immersion cooling.

An experimental investigation on CCFL characteristics during gas/low surface tension liquid counter-current two-phase flow in a small-scaling PWR hot leg typical geometry

A sharp increase in world energy demands which further results in another large progress in the development of nuclear energy establishes comprehensive developments on corresponding mitigation studies. Therefore, as a scenario of accident called LOCA is fundamentally considered, the related phenomena, i.e., the counter-current flow followed by flooding in the primary circuit of PWR, is of a great importance. The present work investigates characteristics of the flooding during a pair of gas/low surface tension liquid counter-current two-phase flow in a complex conduit representing a down-scaled of PWR hot leg typical geometry. Visual observations were obviously carried out to observe the flow phenomenology, while flow parameters were frequently varied. A typical result reveals that the gas flow rate to initiate the flooding decreases with the increase of liquid flow rate. Moreover, exhibiting locations of the onset called locus, a front flooding tends to occur during relatively low liquid flow rates while the higher liquid flow rates exhibit another flooding namely rear flooding. Accordingly, the present investigation provides a package of valuable information on a particular understanding towards the flooding characteristics to overcome the efforts on promoting safety managements on the operation of nuclear power plants..

Analysis of biological mechanism of blood flow containing nanoparticles through an arterial stenosis

ABSTRACT This article aims to discuss the flow of nanoparticles in the blood through a stenosed artery in the presence of a magnetic field and periodic body acceleration. The overlapping shape of stenosis is chosen to show the impact of blood flow. The Bingham plastic fluid model is utilized to capture the non-Newtonian behavior of blood in the stenosed artery under diseased conditions. The resultant equations are solved analytically using the regular perturbation method. The impact of various emerging parameters on velocity, flow rate, effective viscosity, and wall shear stress are presented through graphs and discussed in detail. It is noticed that liquid velocity and flow rate increase whereas effective viscosity decreases with an increase in slip velocity and Womersley’s frequency parameter. It is also noted that liquid velocity and flow rate are decreased by enhancing the Lorentz force. The increase in body acceleration enhances fluid velocity.

A new look to the old solvent: Mass transfer performance and mechanism of CO2 absorption into pure monoethanolamine in a spray column

The most mature CO2 capture technology is absorption of monoethanolamine (MEA) in packed or spray columns. Typically, an aqueous 30 wt.% MEA solution is used. High MEA concentrations are believed to hinder mass transfer rate due to high viscosity of MEA. We worked, for the first time, on the effects of using pure MEA on overall mass transfer coefficient (KGɑ) and absorption efficiency in a spray column by varying several operational parameters. Image analysis results suggested that interfacial area increased with increasing liquid flow rate. As a result, KGɑ increased. As opposed the belief in literature, KGɑ also increased with increasing MEA concentrations. The highest KGɑ was obtained in this work (11.7 kmol·m−³∙kPa−1∙h−1) is around one order of magnitude higher than most literature studies. Having more MEA molecules on the surface of the droplets led to higher KGɑ. In addition, it was shown that absorption efficiency was largely determined by inlet CO2 to MEA molar ratio. 13C NMR spectra results revealed that similar levels of carbamate were formed for MEA concentrations up to 70 wt.%. A simplified analysis on regeneration heat duty showed that decreasing water amount can lead to 3–10 fold decrease in reboiler energy duty.

THREE DIMENSIONAL PORE SCALE STUDY OF HEAT AND MASS TRANSFER IN AN AEROTHERMAL PHASE CHANGE THERMAL PROTECTION SYSTEM USING FOAM STRUCTURE

Aerodynamic heating seriously affects the safety of hypersonic vehicles, which is an urgent problem to be solved. In this work, an aerothermal phase change thermal protection system using foam structure arranged inside aircraft skin is put forward. Firstly, considering the characteristics of aircraft skin, the three-dimensional foam structures, with and without skeleton micropores, is reconstructed. Then, the effects of liquid water mass flow rate and micropores in the foam structure on heat and mass transfer in the aerothermal phase change thermal protection system are investigated. Results show that the aircraft skin temperature decreases fast and then slowly to a platform, with an increase in liquid water mass flow rate. The heat transfer in the foam structure also increases fast and then slowly to a platform, with an increase of liquid water mass flow rate, while the pressure drop for the foam structure increases linearly with an increase in liquid water mass flow rate. The comprehensive heat transfer performance of liquid water flowing along micropores is better than that of liquid water flowing without micropores and vertical to the micropores. The discovery of the above phenomenon helps design a good aerothermal phase change thermal protection system.

Process intensification in a cross-flow rotating packed bed for evaporative cooling of water

Cooling towers are essential devices in any chemical processing industry, air conditioning, petrochemicals, power generation units among others where an enormous amount of waste heat is generated continuously. To cool the equipment, water is generally considered a suitable coolant as it is easily available, non-degrading in nature and can be reused multiple times, and also has a high heat capacity. In this experimental study, the performance evaluation of a packed bed contactor under centrifugal field is done for evaporative cooling of water by an unsaturated gaseous stream wherein the two phases come in contact in a cross-current mode. Rotating packed beds (RPB) are acclaimed Higee (high gravity) devices utilized in process intensification. Here, the action of terrestrial gravity (as in conventional devices) is altered by strong centrifugal acceleration (∼100–1000g). Higee devices have a great impact on the mass transfer rates leading to a drastic reduction in the equipment volume. The performance evaluation is done in terms of evaporation rate of water and thermal efficiency of the Higee contactor and the effect of operating parameters were examined as well. With increase in the gas flow rate and rotational speed there is an increase in the evaporation rate from 0.012 - 0.034 kg/min. There is a minute reduction in the evaporation rate with the increase in liquid flow rate. The maximum and minimum values of thermal efficiency of the contactor in the study are 0.20 and 0.37 respectively. The study depicted that rotating packed beds are cost and time effective and technically feasible for evaporative cooling of water.

Experimental investigation of the particle growth mechanism and influencing factors during granulation process by pyrohydrolysis in fluidized bed

Particle growth kinetics during the pyrohydrolysis of pickling waste liquor in fluidized bed has an important influence on the metal oxide recovery. This study innovatively investigates the particle growth mechanism by combining granulation characteristics in fluidized bed and collision behavior between droplet and heated spherical particle, and then explores the effect of operating parameters on particle growth and powder properties adhered on the surface in the fluidized bed at 800 ℃. The results indicated that the particle growth mechanism was highly dependent on the bed temperature. When T < 100 ℃, it was mainly based on the direct droplet deposition on the surface; at 100 ℃< T < 300 ℃, droplet deposition and powder collision adhesion together promoted particle growth; when T > 300 ℃, the powder adhesion by inertia collision was dominant. The change in particle growth mechanisms was attributed to the liquid-solid interactions. The increasing particle temperature promoted rebound and breakup of droplets after impacting with the particles and then led to fine powder formation in the bed gaps. However, the increase of liquid viscosity was beneficial for the direct adhesion of droplets to the particle surface and accelerated particle growth. The results also found that operating parameters had a significant effect on the granulation characteristics. The coating layer thickness, powder size and porosity all increased with bed temperature. When the bed temperature is 800 ℃, the size of powder and bed particles both increased with the concentration of Fe3+ but decreased with the atomized gas velocity. However, the increase in liquid flow rate led to slower particle growth because of the increase in superheated vapor volume.

Modelling of gas-liquid-solid distribution in the cocurrent three-phase moving bed

The three-phase moving bed reactors (TMBRs) can supply a potential solution for the multi-phase reactions with deactivating catalysts to realize Online Catalyst Replacement (OCR). In this work, computational fluid dynamics (CFD) simulations were employed to investigate the flow behavior of each phase in a cocurrent TMBR. The Euler-Euler multi-phase flow model and two different liquid-solid force models were employed to describe the dense-phase particle flow and liquid-solid interaction, respectively. The results revealed that the solid flow rate increased due to the gas-liquid flow, but radial solids distribution had not changed significantly. The effect of gas-liquid flow on the solid volume distribution was mainly reflected in the wall and inlet region, which led to lower solid volume fraction and higher granular temperature in the local area. Meanwhile, compared with trickle beds, with the increasing gas flow rate or decreasing liquid flow rate, both the liquid holdup and flow dead zone decreased in TMBRs. With the increase in liquid flow rate, the effect of liquid migration (from the wall to the center) on the liquid distribution was weakened. Besides, due to the competition between the pressure gradient force and gas-liquid drag force, the variations of volume and velocity of each phase depended on operating conditions, which were divided into three typical ranges. The gas-liquid-solid distribution could significantly advance the understanding of flow behaviors in TMBRs, based on which the reactor development could be further promoted.

Dynamics of bubble formation in yield stress fluids in parallelized microchannels

The bubble formation in yield stress fluids in parallelized microchannels is investigated experimentally. Nitrogen and Carbopol gel are used as the dispersed and continuous phases, respectively. Due to the feedback effect of the downstream microchannels, the uniformity and stability of bubble formation strongly depends on the properties of gels and operating conditions. The effect of yield stress on the interface evolution during bubble formation is investigated under different mass factions of Carbopol (0.2 %, 0.13 %, 0.05 %) and flow rates of gas (0.1–400 mL·min−1) and liquid (0.03–0.2 mL·min−1). The activation rate of parallel microchannels for bubble production increases with the decrease in the concentrations of Carbopol. The increase of liquid flow rate and the decrease of gas flow rate benefit the uniformity of bubble formation frequency. However, under the double-channel bubble-generation flow pattern, reducing the liquid flow rate significantly improves the stability of bubble formation.

Experimental investigation on dynamic behaviour of bubbles emerging from micro‐capillary orifice in a flow channel

AbstractThe flow phenomenon of liquid with bubbles is widespread in various industrial fields, which determines the mass transfer characteristics of the equipment. In this work, the dynamic behaviour of bubbles emerging from micro‐capillary orifice in a flow channel was studied by a visualization experiment, while the effects of gas flow rate and liquid flow rate on these processes of bubble growth, departure, and inrush were explored. The experimental results showed that one bubble formation cycle can be divided into three stages: Waiting, departure, and inrush, as well as the dynamic behaviour of bubble emerging from micro‐capillary orifice in a flow channel, were significantly affected by gas flow rate and liquid flow rate. At a higher gas flow rate, the growth time and the departure time were shorter, as well as the departure volume of the leading bubble and the inrush volume of the trailing bubble were smaller, while the transverse longitudinal ratio fluctuated more violently, and the swing amplitude of the bubble centroid was greater. With an increasing liquid flow rate, the growth time, the departure time, and the inrush time shortened, while the departure volume of the leading bubble decreased and the fluctuation of the bubble centroid weakened. These findings are conducive to improving the performance of the equipment by optimizing the design of the aerator to regulate the dynamic behaviour of bubbles.

Ozone membrane contactor to intensify gas/liquid mass transfer and contaminants of emerging concern oxidation

A tubular porous borosilicate membrane contactor was investigated for ozone gas/water mass transfer and the removal of contaminants of emerging concern (CECs) in water. Ozone gas/water contact occurs on the membrane shell-side, which is coated with a photocatalyst (TiO2-P25), as the ozone gas stream is fed from the lumen side and permeates through the pores generating micro-sized ozone bubbles uniformly delivered to the annular reaction zone where the contaminated water to be treated flows. Under continuous flow, water pH at 3.0 and temperature at 20 ºC, the volumetric mass transfer coefficient (KLa) ranged from 3.5 to 9.0 min−1 and improved with the increase of gas flow rate (QG, 1.5-fold from 0.15 to 1.0 Ndm3 min−1) and liquid flow rate (QL, 2.0-fold from 20 to 50 L h−1), due to enhanced turbulence on the membrane shell-side and annular zone. The mass transfer efficiency was more pronounced as the QG decreased and the QL increased, which is advantageous for large-scale applications. The main resistances to ozone transfer were in the water phase boundary layer (53–76%) and in the membrane (24–47%; kM = (1.14 ± 0.01) × 10−4 m s−1). For an ozone dose of 12 g m−3 and residence time of 3.9 s, removals ≥ 80% were achieved for 13 of 19 CECs spiked in demineralized water (each 10 µg L−1), demonstrating the applicability of this membrane contactor for ozonation treatment. Photocatalytic ozonation (O3/UVC/TiO2) did not significantly improve the treatment performance due to the low residence time inside the contactor.

Effect of blade packing structure and high-frequency ultrasound on micromixing efficiency enhancement in an RPB reactor

In this study, a rotating packed bed (RPB) reactor equipped with angled blade packings and high-frequency ultrasonic transducers with a frequency of 1.7 MHz was used to enhance micromixing efficiency. In order to investigate the effect of packing structure, blade packings with angles of 0°, 30°, 45°, and 60° to the radial axis of the bed were made. The operational parameters were rotational speed, liquid flow rate and volumetric ratio. All the experiments were performed in the absence and presence of ultrasound. The results showed that the segregation index (Xs) decreases as the rotational speed and liquid flow rate increases, while it increases with an increase of volumetric ratio. Blade packing with an angle of 45° has had the greatest effect on enhancing the micromixing efficiency, and blade packings with an angle of 30° and 60° had the same efficiency and were in the next priority. According to the results, the use of angled blade packing had a much greater effect on enhancing the micromixing efficiency compared to the ultrasound.

Simultaneous desulfurization and denitrification of flue gas enabled by hydrojet cyclone

Boiler flue gas in the chemical industry contains SO2 and nitrogen oxides (NOx). These flue gases not only pollute the environment, but also seriously endanger human health. In this work, we studied the process of jet atomization and swirl enhancement. Then we constructed a miniaturized hydrojet cyclone. After that, we proposed a new type of flue gas purification technology to achieve integrated and efficient desulfurization and denitrification. All studies were based on combining the liquid jet field with the three-dimensional swirl field to increase the mass transfer area of the gas and liquid phases. The industrial sideline test results showed that the gas purification efficiency increased with the increase of inlet velocity and absorption liquid flow rate, Efficiency is always above 80%. Increasing the concentration of activator could significantly improve the desulfurization efficiency by 27%. Increasing the concentration of oxidant was beneficial to denitrification, and the maximum denitrification efficiency of methyldiethanolamine (MDEA) was 98.2%. Overall, this technology can not only help enterprises save maintenance and treatment costs, but also protect the environment by avoiding the harm caused by flue gas pollution.

Amaranth wastewater treatment by intensified ozonation in a rotating zigzag bed

This study investigated the treatment of amaranth wastewater by ozone (O3) in a rotating zigzag bed (RZB), in which a high gravity environment was created to intensify O3 mass transfer and enhance the degradation of amaranth. The degradation effect of amaranth was evaluated in terms of decolorization rate of the wastewater and removal rate of chemical oxygen demand under various operating conditions. Intermediate products of amaranth degradation were also investigated to elucidate the degradation mechanisms of amaranth. Results show that the degradation efficiency generally increased with increase in initial pH, rotational speed of RZB, initial O3 concentration, gas flow rate but declined with increase in both liquid flow rate and initial amaranth concentration. The decolorization rate of the wastewater reached 92.8 % within a liquid retention time of several seconds in the RZB, suggesting that RZB can significantly enhance the mass transfer rate of O3 into liquid and thus improve the degradation efficiency of amaranth.