Bubble Injection Research Articles

The propagation of negative pulsed discharges facilitated by artificially injected gas bubble in water

Abstract The artificial injection of bubbles into the electrode gap can effectively enhance the performance of underwater pulsed spark discharge (UPSD). It is crucial to investigate the morphology and propagation characteristics of discharges for a comprehensive understanding of bubble-stimulated UPSD. This paper presented an extensive study of negative discharges facilitated by the injected large bubble (with a diameter of 3 mm) in UPSD. The bridging effect of the bubble and the morphology and propagation of discharges were observed through the shadowgraph images captured by a high-speed camera. A numerical model was built to analyse the influence of the bubble on the initial electric field distribution between the electrodes. The characteristics of discharges were notably influenced by bubble parameters and energization conditions. Not in all cases could the bubble play the bridging effect role. The effective range of the bubble was roughly confined to a small region near the HV electrode tip. The experimental results obtained in this paper have certain guiding significance for the practical application of UPSD.

Effect of air bubble injection on the thermal performance of a vertical helical coiled tube heat exchanger: an experimental study

This study investigates the effect of air bubble injection on the thermal performance of a vertical counter-current coiled tube heat exchanger. A cylindrical PVC shell (height: 500 mm, diameter: 152.4 mm) was constructed to carry a copper coil with 11 regular turns and covered approximately 76% and 75% of the total shell height and diameter, respectively. The key operational parameters involving the shell side flow rate (2–10 L/min), the coil side flow rate (1–2 L/min), the air flow rate (0–10 L/min) and the temperature difference between the hot and cold fluids ((20 °C, 30 °C and 36 °C) were tested to determine the overall heat transfer coefficient (U). Air was injected into the shell side of the heat exchanger as bubbles with an average diameter of approximately 100 μm via a porous sparger. The results showed that air injection significantly enhanced U, with the highest improvement (158%) occurring at an air flow rate of 6 L/min, while the minimum improvement was 34%. Furthermore, the ratio of the overall heat transfer coefficient with air injection to that without air injection had its maximum value at a shell side flow rate of 6 L/min.

Optimizing gas lift for enhanced recovery in the Asmari formation: a case study of Abu Ghirab field in Southeastern Iraq

The gas lift technique applies gas bubble injection into the vertical wells to raise production. Gas and liquid rates, shifts in flow regimes, and system equilibrium influence this process. This study explores the efficient implementation of gas lift techniques to maximize production from the Asmari Formation in the Abu Ghirab Field, southeastern Iraq, using a continuous gas lift for maximum production rate by PIPESIM TM software. The results of the gas lift design for the four wells (AGCS-33, 26, 28, and 36) show that the Vogel method provided the best results for the gas lift design, and faults and facies distribution impact the gas lift injection and oil production rates. These will become evident with wells AGCS-33 and 36 as their proximity to faults will increase oil production rates with a gas injection rate limit of 7 MMSCF/d. Conversely, for wells 26 and 28, the limit will marginally rise, starting at 5 MMSCF/d. In addition, the effect of gas lift is clearly in the middle western of the crest, which shows an increasing percentage of oil production of 136.6% at minimum rate and 198.5% at maximum for the well AGCS-26, 89.7% and 105.7% for the well AGCS-36. Wellhead pressure has a significant impact on gas-lift performance, and improving gas-lift efficiency can be accomplished using an electric control valve. The feasibility of implementing gas lift in the Asmari Formation depends on the water cut, well location, and water saturation distribution within the Formation.

Investigating the Effects of Air Bubbles Injection Technique on the Cooling Time of Warm Drinking Water

Investigating the Effects of Air Bubbles Injection Technique on the Cooling Time of Warm Drinking Water

Experimental Analysis of Heat Transfer Enhancement in Double Tube Heat Exchanger with Air Injection

Double-tube heat exchangers are frequently utilized due to their low assemble and maintenance cost. In order to extract a large amount of thermal energy at minimum time and cost, an active method of air bubble injection was developed to increase the heat transfer rate through vertical double-tube heat. The current study explores the influence of air bubble injection on the thermal efficiency of vertical double tubes at counter flow. There were two main modes were adopted to conduct the experiments. The first mode was done without air injection (single phase). In the second mode, the air was injected into the heat exchanger's outer tube through a ring tube into the annular side of the heat exchanger. Cold water flow rate was ranged as (3, 3.5, 4, 4.5, 5 LPM) with 17°C temperature, while hot water was kept constant at (3LPM) with inlet temperature 70°C, and air was injected with (0.5, 1, 1.5, 2 LPM). Results found that overall heat transfer was enhanced by (41%), NTU (49%), effectiveness enhanced by (44%) and Nusselt number (45.2%).

Numerical simulation and model development of drag coefficient of bubbles in gas-liquid metal two-phase flow

The occurrence of a steam generator tube rupture (SGTR) accident in a lead-bismuth cooled fast reactor results in the formation of steam bubbles in the liquid lead-bismuth eutectic (LBE). This may degrade heat transfer and power transients in the reactor core due to the migration and accumulation of steam bubbles. To investigate the dynamics of steam bubbles flowing in liquid LBE, it is essential to develop an accurate model for the bubble drag coefficient. In this paper, a three-dimensional numerical model is first established to simulate the injection of high-pressure steam bubbles into a high-temperature LBE molten pool. The model is based on the CLSVOF method. By analyzing the trajectory, velocity, and diameter of bubbles, and combining them with the force equilibrium equation for bubbles, the values of the drag coefficient for bubbles are determined. On this basis, the suitability of current empirical drag models for bubble migration in LBE is evaluated. Finally, the optimal drag coefficient model is selected and further improved. Results reveal that the prediction error of the optimized model for the bubble drag coefficient in liquid LBE is within ±15 %.

Bubble linking anterior growth strategy to prepare hydrogel tubes with different range, branch and voyager function

Hydrogel tubes (HTs) represent a significant facet of hydrogel morphology. Nevertheless, the continuous, rapid, and facile fabrication of hydrogel tubes remains a formidable challenge. In this study, we introduce a novel technique named as Anterior Growth (AG) for the continuous preparation of HTs. This innovative approach employs air bubbles as guidance to direct the growth of polyvinyl alcohol (PVA) HTs crosslinked by copper ions in alkaline solution. Various factors that affect the sizes of HTs from micrometers to millimeters have been explored, including gauge of needles, air bubble volumes, injection rates, and concentrations of NaOH, copper nitrate and PVA. Single HT with various sizes can be easily fabricated by simply adjusting injection rates. The reversibility of PVA-Cu2+ crosslinking makes it possible to produce HTs with multiple branches in a convenient way by generating an orifice out of the HT wall and then repeating the growing process. Inspired by plant thigmotropism, HTs can be guided to grow along designed shapes such as different angles and patterns by combination of air bubble and silicone rubble substrates. Remarkably, this method allows HTs to serve as voyagers navigating intricate flow channels with a projected trajectory, indicating the capabilities of patterning and traversing complex channels. To further application, AG allows other materials to prepare HTs such as sodium alginate or more, showcasing excellent practical value.

Thermal enhancement of a heat exchanger of engine via U-cut and V-cut zigzag strip turbulator combined with bubble injection method

This experimental study proposes a new approach to enhance heat transfer performance inside heat exchangers of engine by tandem utilization of bubble injection and a punched zigzag strip turbulator. The side edges of the zigzag turbulator underwent two distinct geometry modifications, involving V and U shape cuts. These cuts were made at varying zigzag angles, ranging from 60° to 150° and four diffirent surface area. The potential improvement in thermal efficiency of the heat exchanger was evaluated at different inlet Reynolds number ranging from 5390 to 10,860. Based on survey results, it has been demonstrated that at a Reynolds number of 5390, the Nusselt number and friction factor increase by 48% and 154% for U-Cut with a bending angle of 150°, and by 61% and 170% for V-Cut, respectively. Hence, V-cut boasts a TEF of 1.15, representing a 6.5% improvement over U-cut. Additionally, to assess further enhancement, air bubbles with flow rate ranging 2–6 LPM were introduced to the central tube while maintaining the superior geometry. The data suggests that incorporating air bubbles can enhance heat transfer up to 142%, achieving a TEF of 1.17 at an air flow rate of 6 LPM.

Small‐scale measurement of fracture toughness of muddy marine sediments via bubble injection

AbstractMuddy marine sediments are elastic materials in which bubbles grow and worms extend their burrows by fracture. Bubble growth and burrowing behavior are dependent on the stiffness and fracture toughness (KIc) of these muds. This article describes a custom laboratory apparatus to measure the fracture toughness of muddy, cohesive sediments using a bubble injection method. The system induces fracture in sediment samples by incrementally injecting air through a needle inserted into the sediment. The increasing pneumatic pressure is monitored until it drops abruptly, indicating bubble formation. Fracture toughness is then calculated from the peak pressure at which fracture occurred, following cavitation rheology methods developed for soft gels. The system has produced measurements that compare well to previous data but with better spatial resolution, allowing for characterization of spatial heterogeneity on small scales.

Heat transfer augmentation in a double pipe heat exchanger by tandem utilization of bubble injection and novel magnetic turbulators methods

For the purpose of enhancing the thermal efficiency of double-tube heat exchangers, a new technique has been implemented. By integrating a vibrating turbulator and bubble injection technique, this innovative method produces an added turbulence effect. This research aims to experimentally assess the thermal efficiency of employing two active methods concurrently. Different parameters were analyzed, including water flow rates ranging from 0.5 to 4 kg/min and bubble injection flow rates varying from 2 to 6 l/min, to investigate the effects on heat transfer and pressure drop with and without the magnetic turbulator. The results suggest that by incorporating bubble injection, adopting the magnetic turbulator, and simultaneously utilizing both methods, there is a significant improvement in heat transfer. In optimal scenarios, the heat transfer coefficient is amplified by 150.3% through the injection of bubbles, 328.8% through the implementation of magnetic turbulator, and 586.2% when both techniques are employed in tandem. In comparison to the smooth tube, the friction factor ratios were 6.7, 1.6, and 7.8 times higher in the specified cases. The findings indicated that the concurrent utilization of both techniques can yield an added impact on heat transfer. Ultimately, the integrated approach demonstrated a noteworthy thermal enhancement factor value of 3.49.

Abstract WMP39: Incorporation of Automated Robotic Transcranial Doppler to Screen for Patent Foramen Ovale and Quantify Right to Left Shunt Severity in the Evaluation of Ischemic Stroke Patients for Stroke Etiology at a Comprehensive Stroke Center

Background: Patent foramen ovale (PFO) as a source of right-left shunting (RLS) is a recognized risk factor for recurrent stroke in young patients. Current standard care for RLS diagnosis includes transthoracic echocardiography (TTE), transesophageal echocardiography (TEE) and manual transcranial Doppler (TCD) which have disadvantages. The purpose of this retrospective review is to evaluate incorporation of an automated robotic TCD (rTCD) into the standard evaluation for RLS as cause of stroke, as prior studies have indicated higher sensitivity and quantification of RLS size to direct cardiology referral for potential PFO closure. Methods: Between Dec 2021-Oct 2022, 200 stroke patients age <65 were included in this retrospective review. Average age was 55.7 ± 11.1 yrs. All patients had standard TTE and an rTCD (NovaSignal) with saline bubble injection at rest and Valsalva strain for assessment of RLS performed by echo and ultrasound technicians. Neurologists read results, including RLS shunt severity using the Spencer Shunt Grading scale (0-5), where Grade 3-5 is considered large. Results: The rate of positive RLS shunt using rTCD was 55.5% (n=111), of which 23.5% (n=47) were Spencer grade 3+ or higher. No bone window rate was 8.5% (n=17), which is lower than reported manual TCD rates. There were no rTCD RLS shunt negative patients who had a positive TTE or TEE. Of patients who had positive rTCD (n=14) and TTE with bubble, only 5 TTE’s were positive (35.7% sensitivity). Of rTCD positive patients (n=23) who also had TEE with bubble, only 11 were positive (48% sensitivity). And of 15 rTCD Grade 3+ RLS, only 11 TEE with bubble were positive (73% sensitivity). Conclusion: We successfully replaced rTCD for TTE with bubble to screen for RLS on patients who were admitted with a stroke or TIA, with the following advantages. Non-TCD technicians could be trained to perform the tests with accuracy. rTCD was more sensitive in detecting RLS than TTE with bubble. Quantification of RLS severity identified stroke patients with potentially higher risk of recurrence, prioritized to more aggressive medical management and cardiology referral for TEE and potential PFO closure.

First and second law analysis of a heat exchanger equipped with perforated wavy strip turbulator in the presence of water-CuO nanofluid

For the first time, three alternative techniques were used in this research to enhance the thermal performance of a double pipe heat exchanger: the air bubble injection method, the use of a perforated wavy strip turbulator, and the use of Nano fluids as the working fluid. Distinct bubble injection flow rates ranging 2–6 LPM and turbulators with variable hole diameter ratio (D/L) were used in the experiments. Working fluids have included water, air/water, CuO-water, and air/CuO-water with different volume fractions ranging 0.25 % to and 1 %. Based on the findings, the use of Nano fluid, the PWST and bubble injection method increased the heat transfer by 56, 53 and 14.1 %, respectively. Also, the simultaneous employment of these three techniques increases heat transfer and exergy losses up to 2.15 and 1.82 times greater than those of plain pipe, respectively. The double pipe heat exchanger equipped with a perforated wavy strip turbulator with a hole diameter ratio of 6 and bubble injection with m˙a = 6 LPM was chosen as the best-case utilizing net profit per unit transferred heat load (ηp) and thermal performance factor (TEF). In this case, the maximum amount of ηp and TEF are equal to 2.124 × 10−9 and 1.24, respectively.

Temperature lowering of liquid nitrogen via injection of helium gas bubbles improves the generation of parahydrogen-enriched gas.

The para spin isomer of hydrogen gas possesses high nuclear spin order that can enhance the NMR signals of a variety of molecular species. Hydrogen is routinely enriched in the para spin state by lowering the gas temperature while flowing through a catalyst. Although parahydrogen enrichments approaching 100% are achievable near the H2 liquefaction temperature of 20 K, many experimentalists operate at liquid nitrogen temperatures (77 K) due to the lower associated costs and overall simplicity of the parahydrogen generator. Parahydrogen that is generated at 77 K provides an enrichment value of ~51% of the para spin isomer; while useful, there are many applications that can benefit from low-cost access to higher parahydrogen enrichments. Here, we introduce a method of improving parahydrogen enrichment values using a liquid nitrogen-cooled generator that operates at temperatures less than 77 K. The boiling temperature of liquid nitrogen is lowered through internal evaporation into helium gas bubbles that are injected into the liquid. Changes to liquid nitrogen temperatures and parahydrogen enrichment values were monitored as a function of helium gas flow rate. The injected helium bubbles lowered the liquid nitrogen temperature to ~65.5K, and parahydrogen enrichments of up to ~59% were achieved; this represents an ~16% improvement compared with the expected parahydrogen fraction at 77 K. This technique is simple to implement in standard liquid nitrogen-cooled parahydrogen generators and may be of interest to a wide range of scientists that require a cost-effective approach to improving parahydrogen enrichment values.

Ischemic Stroke Post-Transradial Chemoembolization

AbstractTransarterial chemoembolization is one of the approved locoregional treatment options for hepatocellular carcinoma. The procedure is safe; however, stroke may happen as one of the rarest complications. Our patient is a 68-year-old male who underwent transradial chemoembolization to treat hepatocellular carcinoma, who then developed ischemic stroke on postoperative day 1. The possible causes of stroke in our patient will be presented with review of the literature. Although rare, stroke post-chemoembolization can happen. The presence of intratumoral shunt or inadvertent injection of air bubbles in a coexisting right-to-left shun or the use of transradial approach can increase the risk of stroke.

AIR BUBBLE ENCAPSULATION OF EUKARYOTIC CELLS AND THERAPY FAILURES

Background: The purpose of this manuscript is to introduce a newly discovered potential dangers of air bubbles used for therapeutic or diagnostic purposes into the human body.At present, the injection of air bubbles into the human body for diagnostic purpose is viewed positively by the medical/scientific community. In Vitro experiments are presented whereby cells isolation by air bubbles could interfere with chemotherapy treatments.Methods: Author’s own saliva sample was spitted out onto the center of a clean 25X75x1mm glass slide. The sample was placed and focused on the viewing platform of a video microscope. A toothpick was used to harvest inner cheek cells and gently transfer onto the spitted out sample. After focusing, areas were selected showing floating cells and air bubbles. Different laminar levels were observed by cells migrating at different levels.While microscopically observing the sample, the glass slide was disturbed by finger tapping, the aim to induce bubble bursting.Results: Deformed cells were observed when adhering to the outer surface of air bubbles. Additionally, undeformed cells seen at two distinct perpendicular layers when trapped within the floating bubbles. Noticed was a selective attraction of cells by the outer edge of the floating bubbles. Cells attached to the bubble’s edge were being deformed and attracted to each other. Cells were also observed passing unattracted when in a separate laminar flow under the floating bubble. The provocative tapping causing air bubbles to cavitate and burst.Conclusions: The bursting of an air bubble is not the only factor in floating eukaryotic cells deformation. In this manuscript video microscopy and still images are introduced demonstrating a newly found horizontal flat parallel energy field in the periphery of the oxygen bubble. This energy is evident in the free-floating air bubble interface as cheek eukaryotic cells adhere only to the flat round edge of a bubble. Cells are attracted, adhered to each other, and deformed by their own intrinsic attraction. Once the bubble bursts, cells and debris are dispersed, with cells adherence partially disturbed. Cell deformations persisting. It could be hypothesized that cancer cells trapped at different laminar layers inside the bubble be refractory to external chemotherapy agents thus retaining their cancer characteristics.

Early Outcomes of an Artificial Endothelial Replacement Membrane Implantation After Failed Repeat Endothelial Keratoplasty.

The purpose of this study was to report the outcomes of a novel artificial endothelial replacement membrane implant for treating corneal edema after failed repeat endothelial keratoplasty (EK). This was a retrospective interventional case series. Patients with chronic corneal edema underwent removal of the EK graft and implantation of an artificial endothelial replacement membrane (EndoArt, EyeYon Medical, Israel) several months after 2 or more Descemet stripping endothelial keratoplasty procedures. The implant was secured to the posterior corneal surface using an air-gas bubble. Outcome measures included corrected distance visual acuity (logMAR), central corneal thickness, device-related complications, and ocular discomfort. Five eyes of 5 patients underwent EndoArt implantation. Six months after surgery, the synthetic endothelial replacement membrane was well-centered and adherent to the posterior corneal surface, with improvement in central corneal transparency in all patients. Corrected distance visual acuity increased from mean 1.26 ± 0.25 (logMAR) preoperatively to 0.74 ± 0.44 (logMAR) postoperatively (P = 0.06). Central corneal thickness significantly decreased from a mean of 805 ± 135 μm (excluding the EK graft) preoperatively to 588 ± 60 μm (excluding the EndoArt) postoperatively (P = 0.015). No severe device-related complications developed after surgery, although most patients required more than 1 air-gas bubble injection to achieve complete implant adhesion. All patients experienced preoperative reduction in subjective ocular pain. Synthetic endothelial replacement membrane implantation improves central corneal transparency and visual acuity in patients with failed EK and guarded prognosis for repeat keratoplasty. No significant implant-related adverse events occurred after surgery.

Thermal performance enhancement in a double tube heat exchanger using combination of bubble injection and helical coiled wire insert

In this experimental study, a novel approach combining a helical coiled wire (HCW) turbulator and bubble injection (BI) method has been employed to synergistically improve the heat transfer efficiency of double tube heat exchanger. The thermal-frictional characteristics were evaluated by investigating different parameters, including the bubble injection flow rate ranging from 2 to 5 l/min and HCW pitch ranging from 2.5 to 10 mm. For all cases, the thermal enhancement factor (TEF) is employed to determine the optimal configurations. The experimental findings indicate that the introduction of bubble injection, the implementation of the HCW turbulator, and the simultaneous utilization of both methods result in an enhancement of heat transfer by 66 %, 78 %, and 156 % respectively. However, it should be noted that the usage of these methods also leads to an increase in pressure drop. Also, the findings indicate that the integration of two methods yields favorable outcomes in terms of thermal performance when compared to their individual functions. In the optimal scenario, the TEF has the potential to reach a maximum value of 1.28. Furthermore, in order to obtain a more precise comprehension of the relationship between TEF and the parameters under investigation, an empirical equation have been derived and presented.

Enhancing control of air bubbles in water flows through laser-based surface wettability patterning

Air bubble injection has been a widely studied method for reducing frictional drag in fluid flows, especially in the marine industry. However, the lack of control over air bubble stability, size, and shape has hindered its widespread adoption. This study investigates the use of laser-based surface wettability modification techniques to address these challenges by enhancing control over air bubble behavior in water flows. We processed metal plates using nanosecond laser and chemical immersion to create wettability patterns consisting of regions of either superhydrophobicity or superhydrophilicity. Water tunnel experiments were conducted to observe the behavior of air bubbles over these different wettability patterns. The results revealed that surface wettability can be used to control the size and spatial distribution of air bubbles, which can enhance the energy cost-benefit of drag reduction methods in the marine industry. Moreover, this research offers new insights into the potential of laser-based surface wettability modification as a solution for improving the control of air bubble behavior in large-scale applications.

Numerical investigations on the effect of bubble injection on heat transfer of natural convection in laminar flows

AbstractIt was found that the injection of bubbles into liquid can effectively improve heat transfer efficiency, so it is important for industrial applications to investigate the effect of bubble injection on heat transfer. The effect of bubble injection on natural convective heat transfer in steady laminar flows in a vertical channel is investigated using the volume of fluid (VOF) method, and the effects of bubble diameter, Eötvös number (Eo), bubble arrangement, and bubble distance from a hot wall on the heat transfer between the hot wall and liquid are studied, respectively. The results show that bubble injection can effectively improve the heat transfer between the hot wall and liquid; an increase in bubble diameter and Eo can improve the enhancement effect of heat transfer and can expand the enhancement area of heat transfer; the closer to the hot wall a bubble is, the better the enhancement of heat transfer is; and the spacing and arrangement of bubbles also have important effects on the heat transfer between the hot wall and liquid. The comparison shows that the enhancement of heat transfer is the best for the vertical arrangement of double bubbles, which increases the local heat transfer coefficient by 3.2 times. The enhancement of heat transfer generated by bubble injection is related to the degree of disturbance of the local liquid phase caused by bubble injection. The more strongly the local liquid is disturbed, the thinner the local temperature boundary layer becomes, and the better the enhancement of heat transfer is.

Drag reduction in turbulent channel flow by gas perfusion through porous non-hydrophobic and hydrophobic interfaces: Part I

Skin-friction drag in liquid flows can be reduced by several methods including bubble injection into the near-wall region, air layer creation, air cavities, and applied super-hydrophobic coatings. The first three of these methods each has major drawbacks. In the fourth method, the depletion of the trapped air pockets on the super-hydrophobic surfaces (SHSs) in turbulent flows may cause a significant drag increase. To improve FDR in turbulent flows, a novel method is investigated that perfuses air through a porous medium with and without a hydrophobic treatment. A set of experiments has been conducted in a recirculating water tunnel at downstream-distance-based Reynolds numbers to 8.2million. The test model was a flat porous plate and the total wall shear stress was measured by a load cell apparatus. Air was perfused through such interfaces at mass flow rates to 50 L/min. It is noted that downstream persistence is not an issue with this technique as long as perfusion occurs near uniformly along the surface. The results showed that the method with maximum airflow exhibited a total drag reduction of around 10–25% with an untreated surface and about 20–30% with a treated surface.