Height Of Liquid Column Research Articles

Zero-Net Liquid Flow Simulation Experiment and Flow Law in Casing Annulus Gas-Venting Wells

Under casing annulus gas venting, the annulus of the well is in a special state of zero-net liquid flow (ZNLF), leading to gas production without liquid at the wellhead, resulting in significant holdup issues. Therefore, conventional two-phase flow models cannot be used for calculation. To study the flow characteristics of ZNLF in the annulus of the well, this study established a visual experimental device with a total height of 5.4 m, an outer pipe inner diameter of 140 mm, and an inner pipe outer diameter of 72 mm. The flow characteristics of ZNLF were studied by controlling the casing pressure, initial liquid level, and bottom gas injection rate. The experimental results showed that the flow patterns of ZNLF are mainly bubbly flow and churn flow. Bubbly flow occurred at lower gas rates, while churn flow occurred at higher gas rates. In addition, the experiment found that when the gas injection rate and initial liquid column height were controlled to be the same, the liquid holdup decreased as the casing pressure increased. Analysis of the data patterns indicated that the slip velocity is related to the casing pressure. Based on the experimental results of ZNLF in the annulus, this study established standards for flow pattern transitions, holdup, and a pressure drop calculation model. The model results showed good agreement with the experimental results, with errors not exceeding ±5%.

Bioaerosol Emission from Vortex Liquids Contaminated with Escherichia coli Bacteria

Vortex fluids are often present in natural and artificial aquatic environments and are also widely used in industrial water treatment and product manufacturing processes. Vortex processes have been studied quite extensively; however, little attention has been paid to the potential release of biological aerosols to the ambient air in common situations involving microbial-contaminated vortex liquids. The model organism was Escherichia coli, a common Gram-negative coliform bacterium widely present in the aquatic and air environments. This study examines the influence of various parameters, including liquid rotation speed, column height, temperature, surface tension and vessel size, on the rate of bioaerosol formation. A commonly used single-stage bioaerosol impactor was employed to collect microbial aerosols at different process parameters under controlled laboratory conditions. The main results show that bioaerosol production increases markedly with increasing rotation speed, reaching a maximum rate at the highest value used in this project (1300 rpm). The tallness of the liquid column is strongly responsible for the bioaerosol production efficiency reaching a difference of almost one order of magnitude along the range between 45 mm (highest bioaerosol release) and 110 mm used in this research. Fluid temperature and surface tension are also very influential parameters responsible for bioaerosol generation during fluid vortex motion; corresponding results are discussed in this manuscript.

Visualized-experimental assessment on a two-phase thermosyphon loop downcomer state with wide range of filling ratios

The two-phase thermosyphon loop (TPTL), which has an excellent heat transfer performance with simple, compact structure and pump-free advantages, can effectively solve the heat transfer problem under high heat flux. It is necessary to optimize the TPTL to operate in good conditions, especially the state of the downcomer in which the liquid head is one of the critical parameters to determine the driving force of the circulation. However, in the existing studies, the flow features under high filling ratio and high heat flux were ignored in the downcomer. Since a high filling ratio has been proved to have good performance at high heat flux. Herein, the flow characteristics of the TPTL downcomer were seen and quantified using an experimental visual setup under different filling ratios in this study. Two flow features under high heat flux, for the first time, are reported: 1. two-phase flow in the downcomer at high filling ratios. 2. liquid column height oscillation under a partially liquid-filled state. According to the results, the filling ratio significantly impacts the flow characteristics of the downcomer. The TPTL downcomer state, contrary to the traditional understanding, can be partially filled with liquid but not totally filled with fluid all the time, implying that the driving force may be less than the typical assumption. TPTL with a high filling ratio can also provide a maximum gravity pressure head driving force due to the full downcomer. In addition, the bubble pump, which influences by the heat flux, also accelerates the mass flow in the TPTL. Consequently, TPTLs with a high filling ratio showed a significant thermal performance. A partially filled with the liquid phenomenon is demonstrated in moderate filling ratios, and the height of the liquid column will change as the heat flux increases, which indicates the self-regulation of TPTL. When the filling ratio is low, the liquid column height is greatly influenced by the filling ratio. The high liquid column will also give the TPTL excellent thermal performance. The ideal state of a TPTL downcomer is the downcomer filled with two-phase liquid under a high void fraction, which is realized by a high filling ratio TPTL. This paper sheds some light on the downcomer state of TPTLs to optimize the TPTL thermal performance.

Experiments on capacitance based liquid flow meter with parallel channels used in two-phase

A new flow meter has been proposed to measure liquid mass flow rate in a two-phase system. Irrespective of the input flow, the proposed system transforms incoming stream into laminar stratified flow. This configuration offers a promising avenue for assessing liquid flow rates in a two-phase system by leveraging measurements of liquid column height. Extensive performance assessments have been conducted for different vapour and liquid flows. Since the fluid properties are taken into consideration for designing the system, the temperature dependence on the performance of the flow meter also has been studied. The outcome of these studies has yielded a robust correlation between the actual liquid flow rate and the value deduced from the observed liquid column height. The correlation developed between the actual liquid flow rate and that determined from the height of fluid was accurate with an error of ± 3.8 %. It is also found that this flow meter is capable enough to determine the changes in flow conditions with temperature and would provide flow measurements within an error of ± 4 %. This novel two-phase flow meter not only advances the precision of liquid mass flow rate measurements but also demonstrates its adaptability in accommodating changing flow conditions, particularly those driven by temperature dynamics. The findings presented herein underscore the potential of this innovative flow meter as a reliable tool for accurate flow rate determination in diverse industrial applications such as cryogenics, superconductivity, etc.

Experimental and numerical study of a condensation-driven dilution refrigerator

Dilution refrigerators are widely used in the fields of condensed-matter physics and quantum technology. For small cooling power applications, condensation-driven dilution refrigerator utilizes a condensation pump to achieve 3He cryogenic circulation and has advantages of compact structure, small 3He usage, and convenient operation. Related published research mainly focused on the overall system performances, and in-depth thermodynamics and fluid dynamics analyses are lacking. In this paper, a condensation-driven dilution refrigerator was experimentally studied and corresponding numerical simulations were performed. The results of experiments and simulations were compared and analyzed. In the experiments, lowest no-load temperature was 84.4 mK. The experimental cooling power was 1.91 μW @100 mK with a still heating power of 280 μW and the corresponding COP and second-law efficiency of the dilution cold cycle at 100 mK reached 0.0068 and 2.4% with the high temperature of 452 mK, respectively. The experiments also revealed that the charged mixture amount had a certain influence on the performance. With the help of simulations, the heat leak to the mixing chamber was estimated and certain intrinsic features of the cycle were enlightened. The heat leak and Kapitza resistance in the mixing chamber are possibly the main reasons for the differences between experimental and simulation results. Extended study based on the simulation also showed how flowrate variation changed the liquid column height difference and how the requirement of gas circulation and liquefaction set the limit on the minimum still temperature.

Experimental investigation on extraction of shallow geothermal energy by flexible two-phase closed thermosyphons: Effect of geometric parameters

This study investigates the thermal performance of three super-long flexible thermosyphons (SFTSs) fabricated using metal corrugated-pipe under shallow geothermal conditions, aiming to uncover enhanced heat-transfer methods applicable to this innovative design. Field tests are conducted for SFTSs, each with a length of 52.5 m, under various cooling conditions in a drilling environment. The effects of evaporator dimensions and corrugated-pipe shape on the start-up and steady-state thermal performance of SFTSs are also discussed. The results indicate that the whole liquid pool of all SFTSs boils during start-up, even with an initial liquid column height of 15 m. The SFTS with the lower-diameter evaporator demonstrates better thermal performance during both start-up and steady-state operations, with an increase of approximately 31.8% in the heat transfer power under optimal conditions within the test parameters. Moreover, the helicon-shaped corrugated-pipe evaporator provides better thermal performance for SFTSs than the U-shaped corrugated-pipe evaporator, thus resulting in an increase in the heat transfer power by approximately 5.5% under optimal conditions. The maximum heat transfer power achieved in this study is approximately 1227 W when the inlet temperature of cooling water is 3 °C and the flow rate of cooling water is 4500 mL/min, demonstrating the potential of super-long flexible thermosyphon in extracting shallow geothermal energy. These results provide valuable insights into the heat-transfer and enhancement mechanisms of geothermal thermosyphons.

Numerical study of rising Taylor bubbles driven by buoyancy and additional pressure

The Taylor bubble driven by buoyancy and additional pressure is in a non-equilibrium state, which bubble and liquid flow have an accelerated tendency of rising, and the bubble behavior is significantly different with the Taylor bubble in stagnant liquid. In order to understand the dynamic properties of such bubbles, a numerical study was conducted using the coupled level-set and volume-of-fluid (CLSVOF) method combined with the stress-blended eddy simulation (SBES) model. The research results indicated that, due to the additional pressure, the difference between the bubble pressure head and the liquid column height is larger than zero, the pressure gradient force acting on the liquid column is greater than the force of gravity, this makes the bubble have an accelerating upward trend. The bubble shape and liquid film thickness are closely related to the relative bubble velocity, the correlation between dimensionless liquid film thickness and Reynolds number of relative bubble velocity was proposed. In addition, the article analyzed the influence mechanism of bubble shape, which is determined by the stress state of the fluid surrounding the bubble. Under the additional pressure, the axial stress on the bubble top increases significantly, while the radial stress remains almost invariable, which makes the bubble shape gradually become thinner.

Effect of liquid column on process stability and weld formation under ultra-high power fiber laser-arc hybrid welding of thick plates

Liquid column was a common problem in ultra-high power fiber laser-arc hybrid welding (UHLAHW) process, which has an adverse effect on the welding stability and weld formation. Hence, the influence of welding parameters on the behavior of liquid column was investigated systematically, including laser arc recombination process, laser power, and welding speed. As a result, the violent rising liquid column under laser was suppressed markedly after arc addition. However, it was hard to restrain liquid column upturn when laser power was extremely high, because the huge recoil pressure and shear force between metal vapor/plasma and molten pool could increase the upward momentum of melt. Besides, the height of liquid column and volume of spatters were directly influenced by welding speed, due to the welding line energy could significantly influence the flow of melt on the front of keyhole. By optimizing the welding process, the liquid column could be controlled, thereby significantly improving the welding process stability. Finally, a sound weld bead with qualified weld formation and 15.82-mm penetration was produced when the laser power was 21 kW and welding speed was 1.2 m/min under UHLAHW process. This work provides technical guidance for achieving stable welding process and qualified weld formation for thick plates.

Effects of heat source configuration on the welding process and joint formation in ultra-high power laser-MAG hybrid welding

Ultra-high power laser-MAG hybrid welding technology provides an effective method for joining thick plates with high-quality and efficiency. Heat source configuration of laser and arc was verified to play a vital role in conventional hybrid welding process. In this paper, ultra-high power laser-MAG hybrid welding was utilized to weld 20 mm thick Q235 steel for clarifying the effect of heat source configuration on welding process and joint formation. By high-speed photography, welding process was systematically recorded including hybrid plasma morphology, droplet orientation-transfer and molten pool flow. Subsequently, the joint formation was further analyzed via dynamic behaviors of liquid column and keyhole. Results exhibited that a stable arc characteristic and smooth molten pool flow was formed under HM (ultra-high power laser and MAG-leading) mode. Besides, the enlarged and stabilized keyhole would inhibit the height of liquid column and formation of spatters. Finally, a sound weld joint without “ant-colony-like defect” joint formation and 15.82 mm penetration was produced in HM mode. This work provides an effective method and reference for realizing thick plate single pass weldments in the practical industry.

A Novel Computational Model of the Dynamic Response of the Evaporating Liquid-Vapor Interface in a Capillary Channel

A computational model is developed to investigate the dynamic response of an evaporating meniscus during the capillary flow between vertical parallel plates. A previously developed arbitrary Lagrangian-Eulerian (ALE) model was extended to directly track the formation and evolution of the evaporating meniscus during spontaneous liquid penetration within a capillary channel. The two-dimensional time-dependent conservation equations for mass, momentum, and energy were solved in a finite-volume framework implemented on a moving and deforming grid. The sharp interface tracking method developed here enables direct access to the flow variables and transport fluxes at the meniscus with no need for averaging techniques. The model was validated by comparing the predicted dynamic response of the capillary height subject to interfacial evaporation against theoretical results. The effects of wall spacing and liquid superheat on the capillary flow and the evaporation rate were studied. It was found that thermal diffusion adjacent to the meniscus has a critical effect on the evaporation rate, and neglecting it leads to significant overprediction of the evaporation rate. Results show that, in general, inclusion of evaporation causes a reduction of the liquid column height compared to the non-evaporating case. It was also observed that the equilibrium capillary height is inversely proportional to the liquid superheat. Analyses of the transient regime show that evaporation tends to dampen the oscillatory flow regime compared to the non-evaporating meniscus case.

Thermal analysis of a heat pipe assisted passive cooling system for spent fuel pools

Passive cooling is a promising way to remove the decay heat and ensure the security of Spent Fuel Pool (SFP) at emergency conditions. A potential scheme of the passive cooling system consisting of bundles of large separate heat pipes is presented. A numerical model of the heat pipe is established. The model considered the pool boiling effect in the evaporator and self-adjusting of liquid column height in the downcomer. Influences of evaporator outlet vapor quality and corresponding flow resistance are studied. The model shows reasonable agreement with experimental data. Thermal performance and flow features with different working fluids, namely ammonia, water and R134a, under various conditions are analyzed. It is found that there is a minimum condenser height to activate the passive cooling system. Elevate the condenser helps to enhance the system performance when the downcomer is fully liquid filled. But when the downcomer is partially liquid filled, elevation of condenser provides little benefit. Besides, the cooling system functions well in a wide filling ratio range. Increase of filling ratio leads to growth of liquid column height in the downcomer. When the liquid column height comes to the maximum value, the cooling system shows the best heat transfer performance. In long distance heat transport applications, cooling system with water as the working fluid performs poorly. To balance between security and thermal performance, R134a is a better choice for the SFP passive cooling system than ammonia and water.

Design and analysis of smoke flow visualization apparatus for wind tunnel

In the present study, the design and analysis of smoke generator are done for the low-speed wind tunnel. The wind tunnel fan is fitted with the Variable Frequency Drive to produce the wind speed in the range of 3 to 32 m/s with fan speed of 150 to 1500 rpm. The design of smoke generator was done according to Preston Sweeting mist generator principle corresponding to the free stream velocity of 3 m/s. A controlled smoke generator consisting of kerosene reservoir, controlled heater, blower, liquid column height adjustment mechanism, valves etc. was designed and fabricated. The smoke generator produced the smoke at the rate of 154 cm3/s which was close to the design flow rate of 149 cm3/s. To supply the required quantity of smoke in the wind tunnel, the smoke rake of NACA 0010 profile was developed and installed in the rapid contraction section of the wind tunnel to achieve the streamlined flow. The parametric studies were done on the smoke generator at different power inputs and its effects were studied on smoke temperature, smoke discharge and boiling time of the kerosene. The flow visualization was carried out on NACA 0015 airfoil model and the images were captured to examine the flow physics around them under different operating conditions.

Method and Application of Reducing Pressure and Increasing Production in Nanometer Porous Coal Seam

Objectives: In order to deeply analyze the feasibility of reducing pressure and increasing production of coalbed methane wells in nano-porous coal seams and clarify the principle of well selection. Methods: The sensitivity of bottom hole flowing pressure to coalbed methane production is analyzed by establishing productivity equation in stable production period of coalbed methane wells. Combined with the numerical simulation method, the drainage and production effect of L-1 well in the Block A is simulated after reducing the flowing pressure at the bottom of the well. Results: The results show that for CBM wells that have been put into production, the effect of increasing the production can be achieved by reducing the bottom hole flowing pressure, and when the bottom hole flowing pressure is large, reducing the bottom hole flowing pressure can obtain a larger increase in gas production. The cumulative gas production of Well L-1 can be increased by 110x104m3 compared with the previous measures, and the increase rate can reach 85%. Conclusion: Combining with the pressure-reducing and increasing production wells in the Block A, the applicable conditions for pressure-dropping and increasing production to increase the production of CBM wells are proposed, that is, continuous and stable drainage and production, and there is a certain height of liquid column between the moving liquid level and the coal roof before operation.

Modeling and numerical investigation on the effects of filling ratio in a large separate heat pipe loop

Large separate heat pipe is a potential selection to establish the passive cooling system to remove decay heat from the Spent Fuel Pool. In this system, heat pipes are expected to work properly and effectively for a long time without human intervention. Due to the physical dimensions and structures, flow patterns, and fluid distribution in large-scale heat pipes differ from those in conventional ones. Based on the condensation flow patterns, a flow condensation model is presented. Then, a separate heat pipe model considering filling ratio effects is developed. Using the new model, the mean absolute errors of simulation are 5.5% (water), 5.1% (ammonia), and 4.3% (R134a). While in the conventional condensation model, these errors are 29.4%, 9.7%, and 10%. It is found that the influence of filling ratio varies with working fluids. For water heat pipe, the optimal filling ratio is about 17%. Higher or lower filling ratios lead to degradation of heat transfer capacity. For R134a or ammonia, the optimal filling ratio is a range, about 20% to 70%. The boundary of the range relates to both evaporator outlet vapor quality and heat pipe downcomer liquid column height.

Modeling cavitation bubble dynamics in an autoinjector and its implications on drug molecules

The collapse of cavitation bubbles induced by abrupt acceleration of the syringe in an autoinjector device can lead to protein aggregation. The details of bubble dynamics are investigated using an axisymmetric, three-dimensional simulation with passive tracers to illustrate the transport of protein molecules. When a bubble near the syringe wall collapses, protein molecules are concentrated in the re-entrant jet, pushed towards the syringe wall, and then spread across the wall, potentially leading to protein adsorption on the syringe wall and aggregation. This phenomenon is more prominent for bubbles positioned closer to the bottom wall, growing to a larger maximum radius. The bubble’s maximum radius decreases with the bubble’s distance from the syringe wall and air gap pressure, and increases with an increase in liquid column height and nucleus size. The strain rate induced by the bubble collapse is not large enough to unfold the proteins. When the re-entrant jet impacts the bubble surface or syringe wall, the bubble breaks up, generating smaller bubbles with high surface concentration of protein molecules, potentially inducing aggregation in the bulk. The bubble dynamics are influenced by dimensionless distance of the nucleus from the wall, normalized by maximum bubble radius (γ). The re-entrant jet velocity increases with γ, while the maximum liquid pressure, typically 100∼1000 bar, first decreases and then increases with γ. For a cloud of cavitation bubbles, i.e., closely clustered bubbles, coalescence of bubbles can occur, leading to a higher peak pressure at collapse.

The Interface Motion and Hydrodynamic Shear of the Liquid Slosh in Syringes.

Interface motion and hydrodynamic shear of the liquid slosh during the insertion of syringes upon autoinjector activation may damage the protein drug molecules. Experimentally validated computational fluid dynamics simulations are used in this study to investigate the interfacial motion and hydrodynamic shear due to acceleration and deceleration of syringes. The goal is to explore the role of fluid viscosity, air gap size, syringe acceleration, syringe tilt angle, liquid-wall contact angle, surface tension and fill volume on the interface dynamics caused by autoinjector activation. A simplified autoinjector platform submerged in water is built to record the syringe and liquid motion without obstruction of view. The syringe kinematics is imported to the simulations based on OpenFOAM InterIsoFoam solver, which is used to study the effects of various physical parameters. The simulations agree with experiments on the air-liquid interface profile and interface area. The interfacial area and the volume of fluid subject to high strain rate decrease with the solution viscosity, increase with the air gap height, syringe velocity, tilt angle and syringe wall hydrophobicity, and hardly change with the surface tension and liquid column height. The hydrodynamic shear mainly occurs near the syringe wall and entrained bubbles. For a given dose of drug solution, the syringe with smaller radius and larger length will generate less liquid slosh. Reducing the air volume and syringe wall hydrophobicity are also helpful to reduce interface area and effective shear. The interface motion is reduced when the syringe axis is aligned with the gravitational direction.

Design of Portable Air Purge Level Transmitter with Built-in Calibration Feature

In almost all the process industries level is the prominent process parameter which is being monitored and controlled. For level measurement a wide variety of level sensors are available. For level measurement of chemically corrosive liquids or liquids containing suspended solids, specific sensors are used. In such applications, the direct contact of sensor with the fluid is avoided. Air purge or bubbler pipe is the most suitable level measurement method in such cases. In this method, compressed air is forced through the bubbler pipe which is placed in the level measurement tank. This compressed air/gas emerges from the other end of the tube in the form of bubbles. The pressure in the pipe is equal to the head pressure created by the height of liquid column in the tank. The conventional air purge level measurement method has limitations like lack of portability and non-electrical output. This also consumes more power, lacks in scheduled measurement and requires recalibration for the changes in the range. To overcome these limitations a novel portable programmable air purge level transmitter is designed in this paper. The designed system consists of an on board compressor to improve the portability. The electrical output is obtained using MEMS pressure sensor which is mounted on the top of the bubbler pipe. The electrical signal given by the MEMS pressure sensor is converted to standard output using Microcontroller and Signal Conditioning Unit. The system is made programmable using keyboard and display interface to microcontroller. Due to this recalibration and scheduled measurement is possible and this results in reduced power consumption.

Modeling of liquid rise in twisted yarns

This article presents a mathematical model of liquid transport in twisted yarns, considering that yarn twist determines the pore configuration that ultimately decides the extent to which wicking takes place in a yarn. It is shown that that the equilibrium wicking height of liquid initially increases with the increase of packing density of yarn due to higher capillary pressure resulting from reduction of pore size. A further increase of packing density causes a reduction in equilibrium wicking height. The earlier theory of pore geometry in yarns has been modified by including fibre contacts in yarn cross-section for more realistic estimate of pore shape factor and pore size. Unlike previous studies, the present model is derived through a probabilistic arrangement of fibres in yarns and does not assume any theoretical arrangement. The model developed in this work is found to predict the complete experimental results quite satisfactorily for three structurally disparate variants of polyester filament yarns. Highlights Introducing probabilistic theory for fibre contacts into pore geometry to modify previous theories on pore characteristics Pore size and pore shape factor collectively influence the liquid column height, which varies with packing fraction (or twist) Modified theory of pore geometry predicts an inverted ‘U’ shape curve of wicking as per experimental evidences

Visual detection of trace lead(II) using a forward osmosis-driven device loaded with ion-responsive nanogels

A simple and portable thermometer-type device based on forward osmosis-driven liquid column rising is developed for visual detection of trace Pb2+. The device consists of a top indicator tube, a chamber loaded with Pb2+-responsive poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (PNB) smart nanogels and a bottom semipermeable membrane. Upon the recognition of Pb2+, PNB smart nanogels undergo a Pb2+-induced hydrophobic to hydrophilic transition, which simultaneously causes the increase of osmotic pressure inside the device. Driven by this osmotic pressure difference, more Pb2+ solution flows into the device, causing the rise of the liquid column in the indicator tube, which can be directly observed by naked eyes. The relationship between the change of liquid column height and the Pb2+ concentration is investigated for the quantitative detection of Pb2+. With the proposed forward osmosis-driven device, trace Pb2+ as low as 10−10 M in aqueous solutions can be detected. This method provides a novel and simple strategy for the visual detection of trace Pb2+.

Thermal analysis and effects study of evaporator exit vapor quality in a separate heat pipe

A separate heat pipe is a kind of wickless heat pipe in which flow boiling occurs in the evaporator and flow condensation occurs in condenser. The evaporator and condenser can be installed in different places. Working fluid circulates in the heat pipe due to static pressure difference between the evaporator and condenser. The separate heat pipe is a high efficiency heat transfer device which can transport heat for a long distance without considerable losses. It is becoming more and more widely used in various fields, such as heat recovery, solar energy collection, air conditioning, passive cooling and so on. In the present study, a numerical model for a separate heat pipe is established and verified with experimental results. Reasonable agreement with MAE of 3.94% between the model and experimental data is obtained. Further studies depict that vapor quality at evaporator exit varies from 0.1 to 1 and shows great self-adjustment ability under different working conditions. Due to the self-adjustment, the separate heat pipe can maintain its heat transfer performance in the charge range of 0.55 m–1.35 m. And this range is strongly affected by both vapor quality at evaporator exit and liquid column height in the downcomer.