Air Bubble Injection Research Articles

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.

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%).

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.

Study of Monoclonal Antibody Aggregation at the Air-Liquid Interface under Flow by ATR-FTIR Spectroscopic Imaging.

Throughout bioprocessing, transportation, and storage, therapeutic monoclonal antibodies (mAbs) experience stress conditions that may cause protein unfolding and/or chemical modifications. Such structural changes may lead to the formation of aggregates, which reduce mAb potency and may cause harmful immunogenic responses in patients. Therefore, aggregates need to be detected and removed or ideally prevented from forming. Air-liquid interfaces, which arise during various stages of bioprocessing, are one of the stress factors causing mAb aggregation. In this study, the behavior of an immunoglobulin G (IgG) at the air-liquid interface was investigated under flow using macro attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic imaging. This chemically specific imaging technique allows observation of adsorption of IgG to the air-liquid interface and detection of associated secondary structural changes. Chemical images revealed that IgG rapidly accumulated around an injected air bubble under flow at 45 °C; however, no such increase was observed at 25 °C. Analysis of the second derivative spectra of IgG at the air-liquid interface revealed changes in the protein secondary structure associated with increased intermolecular β-sheet content, indicative of aggregated IgG. The addition of 0.01% w/v polysorbate 80 (PS80) reduced the amount of IgG at the air-liquid interface in a static setup at 30 °C; however, this protective effect was lost at 45 °C. These results suggest that the presence of air-liquid interfaces under flow may be detrimental to mAb stability at elevated temperatures and demonstrate the power of ATR-FTIR spectroscopic imaging for studying the structural integrity of mAbs under bioprocessing conditions.

Wall shear stress measurement of turbulent bubbly flows using laser Doppler displacement sensor

A novel wall shear stress meter is developed to promote studies of frictional drag reduction by injecting air bubbles into a turbulent boundary layer. Such studies require a tool having a time resolution sufficiently high to capture the unsteady effect of turbulent characteristics due to various bubble passage patterns. The present study adopts the principle of the heterodyne interferometer to capture of time variation of wall shear stress in turbulent flow up to 500 Hz in sampling frequency. We demonstrate the performance of the tool by applying it to bubbly flows beneath a flat-bottom model ship running at 3 m/s in a towing water reservoir, where bubbles experience wavy passage around a few Hz in frequency. The data obtained by the proposed shear stress meter agree well with Dean's formula for single-phase turbulent channel flow. The scattering of the data across three trials is sufficiently small, at approximately 3 %. This high reproducibility is a great advantage over conventional direct measurements, which have low reproducibility and a large scatter of the data of approximately 15 %. The obtained results represent reasonable drag reductions by injecting bubbles with different void fractions. We also evaluate histogram of the wall shear stress fluctuation to characterize the effect of drag reduction by unsteady passage of bubbles.

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.

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.

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.

An Examination of Air-Bubble Injection Mechanisms for Optimising Heat Transfer in Industrial Applications

An Examination of Air-Bubble Injection Mechanisms for Optimising Heat Transfer in Industrial Applications

Enhancement of heat transfer in a vertical shell and tube heat exchanger using air injection and new baffles: Experimental and numerical approach

Vertical shell and tube heat exchangers play a critical role in many industrial processes, and their importance lies in their high heat transfer efficiency, versatility, compact size, easy maintenance, and longevity. To improve the hydrothermal performance, this research investigates the influences of air bubbles injection inside the shell with disc and ring baffles with circular holes, which is the first time to be addressed. The experiments used a fixed oil mass flow rate with 0.23 kg/s inside the tube sides and various cold water flow rates on the shell side within the 0.15–0.23 kg/s range. Three baffles’ configurations, such as single segmental (SSB), disc and ring (DRB), and disc and ring with circular holes (DRCHB), were investigated with different volume flow rates of air bubbles injection in the shell experimentally. A numerical model is performed and validated for the three baffles shapes. The performance parameters such as number of transfer units, effectiveness, heat transfer coefficient, pressure drop, and performance evaluation criterion are studied. The experimental findings showed that efficacy improved with the increase of the cold-water mass flow rates, whereas the DRCHB baffle shape with air injection)10 × 10−5 m3/s(achieved the highest effectiveness with an enhancement rate of 202% to 231%. The DRCHB configuration with maximum air injection has the highest values of the number of transfer units, heat transfer coefficient, and performance evaluation criterion compared to the other baffles configurations moreover, the pressure drop is the smallest in this case DRCHB without air injection. The numerical results showed that both novel configurations (DRB and DRCHB) have more uniform velocity and temperature distributions compared to the segmental baffles, which may effectively increase the hydrothermal performance.

Sea Ice Formation, Glacial Melt and the Solubility Pump Boundary Conditions in the Ross Sea

AbstractSeasonal formation of Dense Shelf Water (DSW) in the Ross Sea is a direct precursor to Antarctic Bottom Water, which fills the deep ocean with atmospheric gases in what composes the southern limb of the solubility pump. Measurements of seawater noble gas concentrations during katabatic wind events in two Ross Sea polynyas reveal the physical processes that determine the boundary value properties for DSW. This decomposition reveals 5–6 g kg−1 of glacial meltwater in DSW and sea‐ice production rates of up to 14 m yr−1 within the Terra Nova Bay polynya. Despite winds upwards of 35 m s−1 during the observations, air bubble injection had a minimal contribution to gas exchange, accounting for less than 0.01 μmols kg−1 of argon in seawater. This suggests the slurry of frazil ice and seawater at the polynya surface inhibits air‐sea exchange. Most noteworthy is the revelation that sea‐ice formation and glacial melt contribute significantly to the ventilation of DSW, restoring 10% of the gas deficit for krypton, 24% for argon, and 131% for neon, while diffusive gas exchange contributes the remainder. These measurements reveal a cryogenic component to the solubility pump and demonstrate that while sea ice blocks air‐sea exchange, sea ice formation and glacial melt partially offset this effect via addition of gases. While polynyas are a small surface area, they represent an important ventilation site within the southern‐overturning cell, suggesting that ice processes both enhance and hinder the solubility pump.

Energy, exergy, and economic (3E) analysis of air bubbles injection into plate heat exchangers

Energy, exergy, and economic (3E) analysis of air bubbles injection into plate heat exchangers

Recurrent Transient Ischemic Attacks in a Patient with Multiple Pacemaker Leads

Venous complications-specifically, stenosis and thrombosis-are both well-known complications of transvenous implantation of pacemakers and defibrillators. Although they are a well-recognized phenomenon, these complications are rarely of clinical significance. One of the most concerning complications is the development of superior vena cava (SVC) syndrome. Studies have found that the incidence of SVC syndrome varies from 1 in 3,100 to 1 in 650 patients. The azygos-hemiazygos venous system is the most commonly observed collateral. We report a case of a 71-year-old female patient who presented with stroke-like symptoms during the injection of agitated saline bubbles while performing an echo and was found to have an unusual venous collateral circulation formed as a result of brachiocephalic and SVC obstruction from multiple pacemaker leads. Our patient's clinical presentation was extremely unique, and we did not find any cases during our literature search reporting a similar presentation. Multiple collaterals formed between the brachiocephalic and subclavian veins, and bilateral pulmonary veins in our patient allowed the injected air bubbles from the venous system to reach the left side of the heart and eventually the cerebrovascular system, resulting in these transient ischemic attacks. These attacks eventually resolved as the air bubbles were dissolved and washed away by the continuous blood flow. It is advisable to monitor the patient for possible venous stenosis and SVC syndrome after any device insertion during regular device follow-up appointments.

Temporary Pupil Occlusion and Retrolenticular Air Bubble Injection for Descemet Membrane Endothelial Keratoplasty in Vitrectomized Unicameral Eyes.

The aim of this study was to describe a surgical method that can be easily and safely performed during Descemet membrane endothelial keratoplasty in patients who had previously undergone pars plana vitrectomy with transscleral fixation of the intraocular lens. This report reviewed 2 Descemet membrane endothelial keratoplasty procedures performed in patients with vitrectomized unicameral eyes. The proposed technique is characterized by the temporary suture of the pupillary aperture to block the forward flow of vitreous humor and prevent the abrupt loss of air tamponade due to backward movement of the air bubble into the vitreous cavity. At the same time, another air bubble is injected behind the scleral-fixated intraocular lens to induce forward movement of the iris-intraocular lens diaphragm through buoyancy. Thus, the depth of the anterior chamber is reduced, allowing easier unscrolling of the Descemet membrane endothelial keratoplasty lenticule. Pupil closure and buoyancy of the air bubble allow the anterior chamber to be separated from the inflow of vitreous cavity fluid and maintained adequately shallow. During the keratoplasty, the graft is then easily unscrolled without the support of the capsular diaphragm. Postoperatively, the air bubble is maintained in the anterior chamber for a sufficient period. Nd:YAG laser suture lysis is performed after complete absorption of the air bubble during outpatient follow-up. Temporary pupil occlusion and retrolenticular air bubble injection provide a stable surgical approach in challenging cases of postvitrectomized unicameral eyes.

Combined Energetic and Exergetic Performance Analysis of Air Bubbles Injection into a Plate Heat Exchanger: An Experimental Study

This paper aims to give a comprehensive energetic-exergetic performance analysis on the impacts of injecting-submillimeter of air bubbles into both sides of cold and hot water streams before the entrance port of a corrugated plate heat exchanger (C-PHE) having ten plates within counterflow configuration. Hence, optimize the energy and exergy effectiveness at different operating conditions for counter and parallel fluid flow configurations. Hot streams were studied in seven flow rates ranging from 280 L/h to 880 L/h with a regular step of 100 L/h, and constant hot water temperature and cold-water stream of 50 °C and 290 L/h, respectively. Hence, the air was discharged with four flow rates ranging between 150 and 840 L/h. The obtained results showed the vital role of the ABI technique in enhancing the NTU and effectiveness by 59% and 18.6%, respectively, for CWS. The entropy generation was reduced to 0.038 W/K and the augmentation entropy generation number to 0.087 at the low airflow rate for CWS, which are the main parameters for evaluating the EGM. These two parameters increase the Witte-Shamsundar-efficiency to a maximum value of 98.6% at the same operating conditions. Moreover, the exergy effectiveness was enhanced to a maximum value of 80.9% at a high ABI flow rate and low volumetric rate of the hot stream at CWS. The thermo-economic assessment has been carried out, which revelers the positive effects of ABI on the combined energetic and exergetic performance on both sides, i.e., hot and cold sides.

Study of an air bubble curtain along a wall in water and radiated noise mitigation

The injection of air bubbles into the liquid phase of a freestream flow has several impacts on the flow structure, which depends on the volume and size of the bubbles. This work experimentally investigates the characteristics of air bubble injection into freestream flow using three different injector models. The effects of the bubble curtain on the sound wave attention are studied. A wide range of air injection rates from 2 to 50 standard liters per minute is injected into the freestream water at Froude numbers (Fr) of 50.5, 70.7, and 90.9. The injector model is placed on the sidewall, which is where the bubble curtain is generated. High-speed cameras and an image processing technique are used to visualize and quantify the projected void fraction (PVF) of air bubbles. The sound measurement system consists of two hydrophones. The first hydrophone projects sound waves at discrete frequencies ranging from 17 to 50 kHz, and the second receives the transmitted sound waves. The bubble PVF is observed to increase with the air injection rate as the Froude number increases. There is no significant increment in the thickness of the bubbly curtain when the air injection rate or Froude number increases. The different air injector models produce various air bubble flow patterns, and model II provides the highest PVF. The bubble curtain greatly suppresses sound waves at all frequency ranges. However, the sound attenuation rate varies along the frequency range. The insertion loss increases depending on the PVF of the bubbles, freestream velocity, and frequency range. At a high Froude number of 90.9, the increased air injection rate does not affect the insertion loss. Model II has a relatively higher insertion loss rate at frequencies >26 kHz.

Experimental investigation of the effect of air bubbles injection on the performance of a plate heat exchanger

• Air is injected in cold water to enhance the performance of plate heat exchanger . • A first PHEX performance test at various air and hot water flow rates is reported. • NTU and effectiveness are enhanced by up to 12.4 and 14.6 %, respectively. • Entropy generation rate increases up to 4.1 W/K with air bubble injection. • Witte-Shamsundar efficiency reaches a maximum of 96.9% for lowest water flow rate. Injection of sub-millimeter scale air bubbles into liquid flows has been recognized recently as an effective method for thermal performance enhancement of heat exchangers. However, no studies have been reported so far on air injection into the cold liquid stream of plate heat exchangers (PHEX). This approach is investigated experimentally in the present study for the first time in PHEXs to map the energetic and exergetic performance characteristics of a typical PHEXs in terms of the number of transfer units (NTU), effectiveness, entropy generation number, augmentation entropy generation number, rational effectiveness, and Witte-Shamsundar efficiency. Air (150–840 L/h) and hot water (280–880 L/h) streams are mixed in a T-junction mixing chamber before entering the PHEX as a two-phase flow. The results show a remarkable increase in NTU by up to 12.4% due to injected air bubbles, whereas the effectiveness increases by up to 14.6%. On the other hand, considerable increments in entropy generation rate are noticed, reaching a maximum of 4.1 W/K, but this increment was less than 3 folds for most examined cases. Overall, the Witte-Shamsundar efficiency, representing the combined energetic-exergetic performance, reached a maximum of 96.9% at air and hot water flow rates of 350 and 280 L/h, respectively.

The Performance of the U Shape Double pipe heat exchanger under effect of using Active Techniques.

The main aim from this research experimentally studied the effect of external power effect like use the active technique which is represented as an air bubble injection on shell side of of U shape double pipe heat exchanger and in this investigations was used a suitable U shape heat exchanger with different position angle of the U shape Exchanger like position (U shape , ? Inverse U shape ) in additionally used a system which has all the equipments that measuring flow rates and parameters, the vortex generation due to the curvature of bending shell and tube has strong effect to increase the performance of exchanger. The results with this injection inside the shell side demonstrated that the optimize position of exchanger with best performance of parameter was with (?) Inverse and the exchanger enhancement was (24.4%) due to the different shape of diffuser which was used it with inverse U shape exchanger. the air bubble injection as active technique it suggested that the effect cause by the bubble increment the agitation of flow and due to the motion of fluid and air as mixing turbulence flow motion and increased the heat transfer rate and performance parameter of exchanger .