The growth of vapour bubble in a superheated liquid between two phase turbulent flow

2010 ◽  
Vol 88 (5) ◽  
pp. 317-324 ◽  
Author(s):  
S. A. Mohammadein ◽  
A. F. Abu-Bakr
Keyword(s):  
Thermal Diffusivity ◽  
Turbulent Flow ◽  
Present Model ◽  
Bubble Radius ◽  
Superheated Liquid ◽  
Superheated Water ◽  
Vapour Bubble ◽  
Two Phase ◽  
Special Cases ◽  
Growth Problem

In this paper, the growth of a vapour bubble in superheated water for two-phase turbulent flow is studied. The growth problem is formulated by mass and momentum equations under physical assumptions between two finite boundaries. The analytical solution is obtained in terms of the vapour bubble radius. The bubbly growth is affected by thermal diffusivity, superheating, and the Péclet number. The fact that the scale of the bubble is larger than the scale of the turbulence in the mixture surrounding the growing bubble is considered. The previous models of growth for laminar flow are obtained as a special cases of the present model for some values of the parameters a, b, n, and φ0, respectively.

Growth of a vapour bubble in a viscous, superheated liquid in two-phase flow

2015 ◽  
Vol 93 (7) ◽  
pp. 769-775 ◽  
Author(s):  
S.A. Mohammadein ◽  
K.G. Mohamed
Keyword(s):  
Pressure Difference ◽  
Growth Process ◽  
Bubble Radius ◽  
Initial Pressure ◽  
Superheated Liquid ◽  
Necessary Condition ◽  
Physical Parameters ◽  
Vapour Bubble ◽  
Two Phase ◽  
The Given

This paper presents the growth of a vapour bubble in a viscous, superheated liquid. The problem is solved analytically using the Plesset and Zwick method after modifying the pressure difference to include a multiple quantity of the initial pressure difference, its coefficient b giving the necessary condition for the growth process. Relations between the initial and final times in terms of the given physical parameters are derived. The bubble radius is proportional to the thermal diffusivity, the initial pressure difference and its coefficient, while it is inversely proportional to the surface tension, the dynamic viscosity, and the initial void fraction. Moreover, for b = 1 × 10−2, better agreement is achieved to some experimental data than some previous theoretical works, for the initial superheated conditions at 2.1, 3.1, and 4.5 K.

The growth of vapour bubbles in superheated water between two finite boundaries

2001 ◽  
Vol 79 (7) ◽  
pp. 1021-1029 ◽  
Author(s):  
S A Mohammadein ◽  
RA Gab El-Rab
Keyword(s):  
Void Fraction ◽  
Bubble Growth ◽  
Bubble Velocity ◽  
Superheated Water ◽  
Vapour Bubble ◽  
Growth Problem ◽  
Good Agreement

The paper analyses the behaviour of vapour-bubble growth between finite boundaries. The Plesset and Zwick theory is modified by assumptions that are different than those studied before. The growth problem is solved analytically in terms of initial bubble velocity and initial void fraction. The results are compared with those obtained from previous theories and experiment. Good agreement is obtained for certain values of the initial void fraction and the initial bubble velocity. PACS No.: 47.50Dz

scholarly journals Effect of Heat Transfer on the Growing Bubble with the Nanoparticles/Water Nanofluids in Turbulent Flow

2021 ◽  
Vol 8 (1) ◽  
pp. 95-102
Author(s):  
Ahmed K. Abu-Nab ◽  
Ali F. Abu-Bakr
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Turbulent Flow ◽  
Bubble Growth ◽  
Bubble Dynamics ◽  
Pure Water ◽  
Theoretical Data ◽  
Superheated Liquid ◽  
Two Phase ◽  
The Mathematical Model

This paper is devoted to study the effect of heat transfer on the temperature distribution in a superheated liquid during the growth of vapour bubbles immersed in different types of nanoparticles/water nanofluids between two-phase turbulent flow. The mathematical model is formulated and solved analytically depending on Scriven's theory and using the modification of the method of the similarity parameters between two finite boundaries. The characteristics of vapour bubble growth and temperature distribution are obtained by using the thermo-physical properties of nanoparticles nanofluids. The results indicate that the nanoparticle volume concentration reduces the bubble growth process under the effect of heat transfer. The better agreements are achieved, for bubble dynamics in turbulent nanofluid using the appropriate numerical and theoretical data for the values of concentration rate of nanoparticles χ=0,0.2,0.4. The temperature distribution surrounding the regime of bubble growth in pure water is more intensive than in other cases of Al2O3/H2O, Fe3O4/H2O and CuO/H2O nanofluids in turbulent flow. A Comparison of the current solution with previous works is carried out and discussed.

THE MECHANISM OF RAISING AND QUANTIFICATION OF SPECIFIC HEAT FLUX AT BOILING OF NANOFLUIDS IN FREE CONVECTION CONDITIONS

2017 ◽  
pp. 25-34
Author(s):  
V.N. Moraru
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Capacity ◽  
Specific Heat ◽  
Chemical Properties ◽  
Heating Surface ◽  
Physical Models ◽  
Superheated Liquid ◽  
Two Phase ◽  
Boiling Process

The results of our work and a number of foreign studies indicate that the sharp increase in the heat transfer parameters (specific heat flux q and heat transfer coefficient _) at the boiling of nanofluids as compared to the base liquid (water) is due not only and not so much to the increase of the thermal conductivity of the nanofluids, but an intensification of the boiling process caused by a change in the state of the heating surface, its topological and chemical properties (porosity, roughness, wettability). The latter leads to a change in the internal characteristics of the boiling process and the average temperature of the superheated liquid layer. This circumstance makes it possible, on the basis of physical models of the liquids boiling and taking into account the parameters of the surface state (temperature, pressure) and properties of the coolant (the density and heat capacity of the liquid, the specific heat of vaporization and the heat capacity of the vapor), and also the internal characteristics of the boiling of liquids, to calculate the value of specific heat flux q. In this paper, the difference in the mechanisms of heat transfer during the boiling of single-phase (water) and two-phase nanofluids has been studied and a quantitative estimate of the q values for the boiling of the nanofluid is carried out based on the internal characteristics of the boiling process. The satisfactory agreement of the calculated values with the experimental data is a confirmation that the key factor in the growth of the heat transfer intensity at the boiling of nanofluids is indeed a change in the nature and microrelief of the heating surface. Bibl. 20, Fig. 9, Tab. 2.

LIMITATIONS OF THE STOCHASTIC APPROACH IN TWO-PHASE TURBULENT FLOW CALCULATIONS

1996 ◽  
Vol 6 (2) ◽  
pp. 211-225 ◽  
Author(s):  
Keh-Chin Chang ◽  
Wen-Jing Wu ◽  
Muh-Rong Wang
Keyword(s):  
Turbulent Flow ◽  
Stochastic Approach ◽  
Two Phase

scholarly journals Model of a turbulent flow of a two-phase liquid with an uneven distributed phase concentration in a horizontal pipe

2021 ◽  
Vol 1047 (1) ◽  
pp. 012021
Author(s):  
Kh Sh Ilhamov ◽  
D Z Narzullaev ◽  
Sh T Ilyasov ◽  
B A Abdurakhmanov ◽  
K K Shadmanov
Keyword(s):  
Turbulent Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Phase Concentration ◽  
Phase Liquid

Heat Transfer in Porous Media Heated From Above With Evaporation, Condensation, and Capillary Effects

1983 ◽  
Vol 105 (3) ◽  
pp. 485-492 ◽  
Author(s):  
K. S. Udell
Keyword(s):  
Stable State ◽  
Superheated Liquid ◽  
Phase Zone ◽  
Two Phase ◽  
Water Steam ◽  
Zone Length ◽  
Compressed Liquid ◽  
Pressure Lowering ◽  
Darcy’S Equations ◽  
Convection Dominated

Heat and mass transfer characteristics of a sand-water-steam system heated at the top and cooled at the bottom were studied. It was found that at steady-state conditions the system segregated into three regions. The top region was conduction-dominated with the voids containing a stationary superheated steam. The middle region was convection-dominated, nearly isothermal, and exhibited an upward flow of the liquid by capillary forces and a downward flow of steam due to a slight pressure gradient. The bottom portion contained a stationary compressed liquid and was also conduction dominated. The length of the two-phase convection zone was evaluated through the application of Darcy’s equations for two-phase flow and correlations of relative permeabilities and capillary pressure data. The model was in excellent agreement with the observed results, predicting a decreasing two-phase zone length with increasing heat flux. The thermodynamics of the two-phase zone were also analyzed. It was found that the vapor phase was in a superheated state as described by the Kelvin equation for vapor pressure lowering. Also, it was evident that the liquid must also be superheated for thermodynamic equilibrium to result. A stability analysis demonstrated that the superheated liquid can exist in an unconditionally stable state under conditions typical of porous systems. The degree of liquid superheat within the two-phase zone of these experiments was obtained.

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