Bubble Breaker Research Articles

Numerical and Orthogonal Study on Optimization Analysis of Structure Parameters of Bubble Breaker for Electrical Submersible Pump System

Abstract Under slug flow conditions, electrical submersible pumps (ESPs) show a low efficiency due to Taylor bubbles, which cause pressure surging and gas pockets and the further deterioration of pressure boosting ability. In this study, a novel downhole bubble breaker is designed for mitigating the impact in ESP under slug flow conditions. The computational fluid dynamics-population balance model (CFD-PBM) coupled approach was used to calculate the bubble breaker's average bubble diameter to evaluate its efficiency. Meanwhile, experimental studies were conducted and compared with numerical results. Also, matlab and DIP-image technology was used to calculate the bubble diameter. Compared with experimental results, the simulation results agree well. Furthermore, the novel bubble breaker's performance was studied by orthogonal approach. The best result of range analysis is A2B3C4D1E4 (α = 30 deg, L = 300 mm, R = 2:1, vsg = 0.2 m/s, and vsl = 0.08 m/s), and sensitively analysis results present that the range of impact intensity are A (inlet angle) > E (superficial gas velocity) > B (total length) > D (superficial liquid velocity) > C (ratio of the gas–liquid channel). The optimal structure's bubble diameters are all less than that of the original structure, with a superficial gas velocity range of 0.2–0.6 m/s. The downstream bubble diameter of the optimal bubble is about 31.6% lower than the original structure at the maximum value point.

The Influence of Temperature and Gas Flow Rate on the Formation CaCO3 Vaterite Phase

CaCO3 powder is much needed in the industry. CaCO3 vaterite phase is widely used as raw material in the pharmaceutical and cosmetic industries. PCC can be synthesized from natural limestone. Indonesia has abundant limestone reserves and has a very high purity1. In this study, the synthesis of CaCO3 powder was carried out at 29 °C and 40 °C by carbonation method without and by using gas bubble breakers. Characterization of CaCO3 with SEM and XRD shows the formation of calcite and vaterite phases. The formation of the vaterite phase CaCO3 is very sensitive in the changes of temperature and CO2 gas flow rate. The formation of a vaterite phase without a gas bubble breaker is increased linearly. In contrast to the gas bubble breaker the formation of vaterite is saturated after a CO2 gas flow rate of 2.3 lt/min.

One-dimensional interfacial area transport for bubbly two-phase flow in vertical 5 × 5 rod bundle

For the modeling of the interfacial structure characteristics, an experiment of vertical adiabatic air-water flow has been conducted under an atmosphere pressure condition. The experimental facility is composed of 5 × 5 rods arranged on a square pitch in a square casing with 9.5 mm outside rod diameter and 12.6 mm pitch, simulating a prototypic rod bundle in nuclear reactors. The miniaturized four-sensor conductivity probe has been developed to allow for the experimental measurement in the small flow channel. Extensive data are acquired for one-dimensional flow parameters including axial development of void fraction, interfacial area concentration and gas velocity. The effect of a prototypic spacer grids with mixing vanes on the flow structure has been discussed at various flow conditions based on the experimental data. Two competing effects, “swirling effect” and “bubble breaker effect”, are identified. The effect vanishes out within a short distance from the space grid. A drift-flux correlation is developed for predicting void fraction of adiabatic bubbly two-phase flow in a vertical rod bundle. Existing interfacial area correlations are tested and Hibiki-Ishii correlation (2002b) is recommended as most accurate correlation to predict the interfacial area concentration. It is expected that the newly obtained data in the 5 × 5 rod bundle is useful for developing the interfacial area transport equation and benchmarking a computational code.

Experimental studies on retention of iodine in a wet scrubber

In order to develop an iodine scrubbing model for nuclear severe accidents, experimental data on filtration efficiency of a wet scrubber for gaseous molecular iodine are collected to improve understanding of the basic mechanisms involved in iodine chemical scrubbing. A bubble column reactor 1.5 m high and 0.2 m in diameter equipped with an injection nozzle and a bubble breaker is used to investigate retention under relevant flow regimes. Scrubber is loaded with a scrubbing solution containing sodium hydroxide and sodium thiosulphate, no irradiation is provided. Retention efficiency is found to be strongly dependent on flow regime and on residence time as models predict. It was found that jet-like injection has a strong effect on filtration efficiency introducing a significant dependence on iodine initial concentration in gas phase believed to be due to nozzle hydrodynamics.

The effect of mesh-type bubble breaker on two-phase vertical co-flow

The influence of a mesh-type bubble breaker in a two-phase vertical co-flow is experimentally investigated using high-speed imaging. A range of liquid and gas flow rates were considered that correspond to the gas-to-liquid flow rates ratios (GLRs) from 0.05 to 39.6 covering bubbly, slug and churn flow regimes. The mesh-type bubble breaker was found to be effective in reducing the size of nozzle-generated bubbles in two-phase co-current vertical flow. The bubble size reduction by 50%-70% is observed in the presence of the mesh-type bubble breaker compared to that without a bubble breaker. The results also show that at a given GLR, the mesh-type bubble breaker delayed the flow regime transition compared to that without a bubble breaker. A Froude number correlation was proposed to predict the mean bubble size downstream of the bubble breaker for the bubbly flow regime, which accurately predicted the bubble size over a range of bubble breaker parameters. It is observed that the geometry of the bubble breaker influence the two-phase flow regime transition. At low liquid flow rates, small pore size of the breaker was found to be effective. This effect diminishes at higher liquid flow rate due to the elongation of the bubbles by the liquid inertia. The results also show that a longer bubble breaker located closer to the bubble generating nozzle is the most effective in producing bubbly flow over a longer range of gas-liquid flowrates ratios.

Performance of Inclined Baffle Column for Pectin Continuous Extraction Process from Cocoa Peel (Theobromacacao)

Pectin from cocoa peel was successfully prepared by extraction method in the bubble column reactor. The process could be carried out in batch and continuous, with co-current or counter current flow. Bubble pipe reactor with inclined baffle is expected to reduce the problem from gas flow patterns, jagged sloping bulkhead serves as a bubble breaker that could replace mechanical stirrer. In this study the reactor column sloping bulkhead was used as extractor to recover pectin in the cocoa peel by citric acid (1 N) solvent. Cocoa peel paste and citric acid were entered to the top of the column at 1 : 1 rate ratio by streamed using dosing pump. Nitrogen gas as a medium stirrer flowed counter current from the bottom of the column. Once extraction was completed, the liquid then precipitated by acid alcohol. Pectin solids were washed with alcohol (96%). The temperature of extraction process is maintained at 70° C. The residence time in the column material was determined by feed flow rate (cocoa paste and citric acid), and the volume of suspension that remains in the reactor (V). Residence time equation obtained is: t = (7045.86G -0.1275 )/L. The yield of yellowish white precipitate reached up to 5.2973% and methoxyl concentration reached 5,21% for 72 minutes. The experiment shows that the continuous extraction process of pectin in baffle columns is better than batch process.

An educational software tool to teach hyper‐heuristics to engineering students based on the bubble breaker puzzle

ABSTRACTThis paper presents an educational software tool to teach Artificial Intelligence (AI) techniques, specifically Hyper‐heuristics, to Engineering students. This tool is based on the “Bubble Breaker” puzzle, an addictive game consisting in an M × M matrix of colored bubbles. These balls, when forming sets of two or more same colored balls, can be popped and cleared out. Thus, this puzzle can be solved by setting many different low‐level heuristics and applying a global search procedure (i.e., evolutionary algorithm) that conforms a robust hyper‐heuristic technique. The hyper‐heuristic decides what low‐level heuristics are the best, and the sequential way in which they have to be applied to gain the highest score. This approach has proven an interesting method to teach AI techniques, since simple heuristics, evolutionary algorithms, and its combination are studied in an increasing manner. © 2014 Wiley Periodicals, Inc. Comput Appl Eng Educ 23:277–285, 2015; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.21597

Ethanol resistive microbubble test: a modification of the stable microbubble test used to predict respiratory distress syndrome.

The stable microbubble (SM) test on gastric aspirate obtained at birth proved useful in identifying infants who would develop respiratory distress syndrome (RDS). This test involves only the count of stable microbubbles of < or = 15 microns in diameter. Larger bubbles (> 15 microns in diameter) are not necessary for the test and may interfere with stable microbubble counting. The aims of the present study were to determine: (i) if larger bubbles could be selectively removed by adding ethanol, a potent bubble breaker; and (ii) if the predictive value of this modified test, the ethanol resistive microbubble (ERM) test, on the development of RDS was similar to that of the SM test. Varying amounts of different concentrations of ethanol-water solutions were added to the top of the bubble crop generated by the SM test procedure, and the mean counts of stable microbubbles and larger bubbles in five regions were calculated. A volume of 10 microL of 47.5% ethanol was effective in defoaming larger bubbles generated by the SM test procedure without altering the stable microbubble counts. When concurrently performed on 43 samples of gastric aspirate obtained at birth from infants of less than 35 weeks gestation, the RDS predictive value of the ERM test was similar to that of the SM test. It was concluded that the ERM test may serve as an alternative to the SM test.

Heat transfer and hydrodynamic studies on two- and three-phase fluidized beds of floating bubble breakers

Heat transfer characteristics in three-phase fluidized beds of floating bubble breakers have been studied in a 0.142 m I.D. x 2.0 m high Plexiglas column fitted with an axially mounted cylindrical heater. Effects of the liquid and gas velocities, the particle size, the volume ratio of floating bubble breaker to particles on phase holdup, the vertical bubble length, and the heat transfer coefficient have been determined. In the bubble-coalescing regime, the heat transfer coefficient in three-phase fluidized beds having the volume ratio V f/ V s of 10–15% produced a maximum increase in heat transfer coefficient of about 20% in comparison to that in the bed without floating bubble breakers. Also, bubble length and gas-phase holdups exhibited their maximum and minimum values at a volume ratio of 10–15%. The heat transfer coefficient in three-phase fluidized beds of floating bubble breakers can be estimated from the surface renewal model with isotropic turbulence theory. Heat transfer coefficients expressed in terms of the Nusselt number have been correlated with the particle Reynolds number and the volume ratio of floating bubble breakers to particles.

BUBBLE CHARACTERISTICS IN THREE PHASE FLUIDIZED BEDS OF FLOATING BUBBLE BREAKER

Abstract The local bubble phase holdup and vertical bubble length in three phase fluidized beds and the beds of floating bubble breaker have been studied in a 15.2 cm-ID pyrex glass column The effects of liquid velocity (1–9 cm/s), gas velocity (2–12 cm/s), particle size (1–6 mm) and the volume ratio of the floating bubble breaker to solid particles (0–30 %) on bubble properties at the different bed heights have been determined The bubble phase holdup increased with gas velocity, volume ratio of floating bubble breaker to solids and particle size along the bed height but decreased with liquid velocity. The vertical bubble length increased with gas velocity along the bed height but decreased with liquid velocity, particle size and the volume ratio of floating bubble breaker to solid particles The local bubble phase holdup and the vertical bubble length have been correlated with the experimental variables as well as dimension less groups of Froude and Weber numbers.