Quantification of a Single Gas Bubble Growth in Solvent(s)–CO2–Heavy Oil Systems With Consideration of Multicomponent Diffusion Under Nonequilibrium Conditions

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Yu Shi ◽  
Daoyong Yang
Keyword(s):  
Growth Rate ◽  
Heavy Oil ◽  
Bubble Growth ◽  
Bubble Radius ◽  
Motion Equation ◽  
Liquid Volume ◽  
Gas Bubble ◽  
Viscous Term ◽  
Proposed Model ◽  
Nonequilibrium Conditions

A mechanistic model has been developed and validated to quantify a single gas bubble growth with considering multicomponent gas diffusion in solvent(s)–CO2–heavy oil systems under nonequilibrium conditions. Experimentally, constant-composition expansion (CCE) experiments are conducted for C3H8–CO2–heavy oil systems under equilibrium and nonequilibrium conditions, respectively. Theoretically, the classic continuity equation, motion equation, diffusion–convection equation, real gas equation, and Peng–Robinson equation of state (PR EOS) are integrated into an equation matrix to dynamically predict gas bubble growth. Also, the viscous term of motion equation on the gas phase pressure is included due mainly to the viscous nature of heavy oil. The newly proposed model has been validated by using the experimentally measured gas bubble radius as a function of time with good accuracy. Combining with the experimental measurements, the critical nucleus radius and gas bubble growth are quantitatively predicted with the newly proposed model. Effects of mass transfer, supersaturation pressure, mole concentration of each component, liquid cell radius, and pressure decline rate on the gas bubble growth are examined and analyzed. In general, gas bubble growth rate is found to increase with an increase of each of the aforementioned five parameters though the contribution of individual component in a gas mixture to the bubble growth rate is different. A one-step pressure drop and the unlimited liquid volume surrounding a gas bubble are considered to be the necessary conditions to generate the linear relationship between gas bubble radius and the square root of time.

The quasi-static growth of CO2 bubbles

2014 ◽  
Vol 741 ◽  
Author(s):  
Oscar R. Enríquez ◽  
Chao Sun ◽  
Detlef Lohse ◽  
Andrea Prosperetti ◽  
Devaraj van der Meer
Keyword(s):  
Boundary Layer ◽  
Growth Rate ◽  
Early Phase ◽  
Bubble Growth ◽  
Bubble Radius ◽  
Combined Effects ◽  
Gas Bubble ◽  
Final Phase ◽  
Concentration Boundary ◽  
Bubble Detachment

AbstractWe study experimentally the growth of an isolated gas bubble in a slightly supersaturated water–CO2 solution at 6 atm pressure. In contrast to what was found in previous experiments at higher supersaturation, the time evolution of the bubble radius differs noticeably from existing theoretical solutions. We trace the differences back to several combined effects of the concentration boundary layer around the bubble, which we disentangle in this work. In the early phase, the interaction with the surface on which the bubble grows slows down the process. In contrast, in the final phase, before bubble detachment, the growth rate is enhanced by the onset of density-driven convection. We also show that the bubble growth is affected by prior growth and detachment events, though they are up to 15 min apart.

Effects of Bubble Growth and Solidification Rate on Pore Formation in Solid

2012 ◽  
Author(s):  
P. S. Wei ◽  
S. Y. Hsiao
Keyword(s):  
Growth Rate ◽  
Contact Angle ◽  
Solidification Front ◽  
Bubble Growth ◽  
Pore Formation ◽  
Solidification Rate ◽  
Bubble Radius ◽  
Abel Equation ◽  
Spherical Cap ◽  
Factors Affecting

The shapes of a pore in solid resulted from entrapment of a tiny bubble by a solidification front are predicted in this work. Pore formation and its shape in solid are one of the most critical factors affecting properties and microstructure, in materials. For simplicity without loss of generality, the tiny bubble is considered to have a spherical cap. From a geometrical analysis, the contact angle of the bubble cap on the solidification front or the pore shape in solid is found to be governed by the Abel equation of the first kind. The pore becomes closed by imposing a finite bubble growth rate-to-solidification rate ratio which can produce a minimal bubble radius at the contact angle of 90 degrees. Closure of a pore resulted from a greater solidification rate than bubble growth rate, as accepted in the literature, is incorrect.

Prediction Model for Bubble Contact Circle Diameter on Heating Wall

2010 ◽  
Author(s):  
De-qi Chen ◽  
Liang-ming Pan
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Bubble Growth ◽  
Bubble Radius ◽  
Growth Time ◽  
Heating Wall ◽  
Contact Circle ◽  
Proper Values ◽  
Circle Diameter ◽  
Contact Diameter

Phenomenal and theoretical analysis about the evolution of bubble contact circle diameter during bubble growing is presented in current paper; and it is found that bubble contact diameter is dependent on bubble growth rate and bubble radius strongly. By analyzing experimental data from open literature, the relation between dimensionless bubble contact diameter, kw, and dimensionless bubble growth time, t+, is obtained; based on this, a model relative to dimensionless bubble growth rate, dR+/dt+, and dimensionless bubble radius, R+, is proposed for prediction of bubble contact diameter. With proper values for coefficients, aw and nw, this model can well predict experimental data of bubble circle contact diameter in published literatures, with an error within ±20%.

Understanding gas bubble trauma in an era of hydropower expansion: how do fish compensate at depth?

2020 ◽  
Vol 77 (3) ◽  
pp. 556-563 ◽  
Author(s):  
Naomi K. Pleizier ◽  
Charlotte Nelson ◽  
Steven J. Cooke ◽  
Colin J. Brauner
Keyword(s):  
Bubble Growth ◽  
Gas Bubble ◽  
Hydroelectric Dams ◽  
Dissolved Gas ◽  
Empirical Relationships ◽  
Lethal Effects ◽  
Exposed Fish ◽  
Total Dissolved Gas ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
The Relationship

Hydrostatic pressure is known to protect fish from damage by total dissolved gas (TDG) supersaturation, but empirical relationships are lacking. In this study we demonstrate the relationship between depth, TDG, and gas bubble trauma (GBT). Hydroelectric dams generate TDG supersaturation that causes bubble growth in the tissues of aquatic animals, resulting in sublethal and lethal effects. We exposed fish to 100%, 115%, 120%, and 130% TDG at 16 and 63 cm of depth and recorded time to 50% loss of equilibrium and sublethal symptoms. Our linear model of the log-transformed time to 50% LOE (R2 = 0.94) was improved by including depth. Based on our model, a depth of 47 cm compensated for the effects of 4.1% (±1.3% SE) TDG supersaturation. Our experiment reveals that once the surface threshold for GBT from TDG supersaturation is known, depth protects rainbow trout (Oncorhynchus mykiss) from GBT by 9.7% TDG supersaturation per metre depth. Our results can be used to estimate the impacts of TDG on fish downstream of dams and to develop improved guidelines for TDG.

Collective Effects on the Growth of Vapor Bubbles in a Superheated Liquid

1984 ◽  
Vol 106 (4) ◽  
pp. 486-490 ◽  
Author(s):  
G. L. Chahine ◽  
H. L. Liu
Keyword(s):  
Collective Behavior ◽  
Bubble Growth ◽  
Theoretical Study ◽  
Pressure Field ◽  
Bubble Radius ◽  
Significant Inhibition ◽  
Collective Effects ◽  
Superheated Liquid ◽  
Vapor Bubbles ◽  
Bubble Interaction

The problem of the growth of a spherical isolated bubble in a superheated liquid has been extensively studied. However, very little work has been done for the case of a cloud of bubbles. The collective behavior of the bubbles departs considerably from that of a single isolated bubble, due to the cumulative modification of the pressure field from all other bubbles. This paper presents a theoretical study on bubble interaction in a superheated liquid during the growth stage. The solution is sought in terms of matched asymptotic expansions in powers of ε, the ratio between rb0, a characteristic bubble radius and l0, the interbubble distance. Numerical results show a significant inhibition of the bubble growth rate due to the presence of interacting bubbles. In addition, the temperature at the bubble wall decreases at a slower rate. Consequently, the overall heat exchange during the bubble growth is reduced.

scholarly journals Sales Growth Rate Forecasting Using Improved PSO and SVM

2014 ◽  
Vol 2014 ◽  
pp. 1-13 ◽  
Author(s):  
Xibin Wang ◽  
Junhao Wen ◽  
Shafiq Alam ◽  
Xiang Gao ◽  
Zhuo Jiang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Decisive Role ◽  
Convergence Speed ◽  
Classification Model ◽  
Support Vector ◽  
Local Optimum ◽  
Sales Growth ◽  
Local Optima ◽  
Proposed Model ◽  
Forecasting Performance

Accurate forecast of the sales growth rate plays a decisive role in determining the amount of advertising investment. In this study, we present a preclassification and later regression based method optimized by improved particle swarm optimization (IPSO) for sales growth rate forecasting. We use support vector machine (SVM) as a classification model. The nonlinear relationship in sales growth rate forecasting is efficiently represented by SVM, while IPSO is optimizing the training parameters of SVM. IPSO addresses issues of traditional PSO, such as relapsing into local optimum, slow convergence speed, and low convergence precision in the later evolution. We performed two experiments; firstly, three classic benchmark functions are used to verify the validity of the IPSO algorithm against PSO. Having shown IPSO outperform PSO in convergence speed, precision, and escaping local optima, in our second experiment, we apply IPSO to the proposed model. The sales growth rate forecasting cases are used to testify the forecasting performance of proposed model. According to the requirements and industry knowledge, the sample data was first classified to obtain types of the test samples. Next, the values of the test samples were forecast using the SVM regression algorithm. The experimental results demonstrate that the proposed model has good forecasting performance.

Nuclei and Cavitation

1970 ◽  
Vol 92 (4) ◽  
pp. 681-688 ◽  
Author(s):  
J. William Holl
Keyword(s):  
Bubble Growth ◽  
Scale Effects ◽  
Gas Bubbles ◽  
Gas Content ◽  
Gas Bubble ◽  
Cavitation Nuclei ◽  
The Stability

This paper is a review of existing knowledge on cavitation nuclei. The lack of significant tensions in ordinary liquids is due to so-called weak spots or cavitation nuclei. The various forms which have been proposed for nuclei are gas bubbles, gas in a crevice, gas bubble with organic skin, and a hydrophobic solid. The stability argument leading to the postulation of the Harvey model is reviewed. Aspects of bubble growth are considered and it is shown that bubbles having different initial sizes will undergo vaporous cavitation at different liquid tensions. The three modes of growth, namely vaporous, pseudo, and gaseous are presented and implications concerning the interpretation of data are considered. The question of the source of nuclei and implications concerning scale effects are made. The measurement of nuclei is considered together with experiments on the effect of gas content on incipient cavitation.

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