Simultaneous mapping of single bubble dynamics and heat transfer rates for SiO2/water nanofluids under nucleate pool boiling regime

Nucleate flow boiling is a liquid-vapor phase-change process associated with high heat transfer rates. A complete 3D numerical simulation of single bubble dynamics on surfaces inclined at 90°, 45° and 30° to the horizontal line and subjected to forced flow parallel to the surface is performed in this work. The continuity, momentum and energy equations are solved with finite difference method and the level-set method is used to capture the liquid-vapor interface. The heat transfer contribution of the micro-layer between the solid wall and evolving liquid-vapor interface is included in this numerical analysis. The effect of dynamic contact angle is also included. The numerical result of bubble growth and sliding distance have been compared with experimental data.

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Experimental Study of Effect of Nucleation Site Size on Bubble Dynamics during Nucleate Pool Boiling Heat Transfer

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.592-594.1596 ◽

2014 ◽

Vol 592-594 ◽

pp. 1596-1600 ◽

Cited By ~ 3

Author(s):

Abdul Najim ◽

Anil R. Aacharya

Keyword(s):

Heat Transfer ◽

Boiling Heat Transfer ◽

Bubble Dynamics ◽

Bubble Diameter ◽

Pool Boiling ◽

Growth Period ◽

Nucleation Site ◽

Hypodermic Needle ◽

Nucleate Pool Boiling ◽

Pool Boiling Heat Transfer

In this paper, effect of nucleation site size on bubble dynamics during nucleate pool boiling heat transfer in saturated water is studied experimentally. Single bubble was generated using right angle tip of a hypodermic needle as a nucleation site. The hypodermic needles were used of inner diameters 0.413mm, 0.514mm, and 0.603 mm with a constant depth of 25mm. The bubble dynamics was studied using SONY Cyber-shot DSC-H100 camera operating at 30 frames per second at atmospheric pressure and at a wall superheat of 5K. The results show that, bubble diameter, bubble height and bubble volume increases with increase in diameter of nucleation site. The bubble growth period is found to be dependent on nucleation site size, and it decreases with increase in diameter of nucleation site. This happens because as volume of vapor bubble increases, buoyancy force starts dominates the capillary force and bubble detaches earlier. Effect of nucleation site size on bubble departure diameter and bubble release frequency is also discussed.

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Numerical Simulation of Single Bubble Dynamics During Pool and Flow Boiling Conditions

Volume 2: Heat Transfer Enhancement for Practical Applications; Fire and Combustion; Multi-Phase Systems; Heat Transfer in Electronic Equipment; Low Temperature Heat Transfer; Computational Heat Transfer ◽

10.1115/ht2012-58089 ◽

2012 ◽

Author(s):

Adam Becker ◽

Marek Kapitz ◽

Stefan aus der Wiesche

Keyword(s):

Heat Transfer ◽

Bubble Dynamics ◽

Flow Boiling ◽

Three Dimensional ◽

Theoretical Data ◽

Single Bubble ◽

Transient Temperature ◽

Spatio Temporal ◽

Major Attention ◽

Single Bubble Dynamics

Complete three-dimensional numerical simulations of single bubble dynamics under pool and flow boiling conditions are carried out using the CFD code FLOW3D© based on the volume-of-fluid (VOF) method. The analyses include a numerically robust kinetic phase change model and transient wall heat conduction. The simulation approach is calibrated by comparison with available experimental and theoretical data. It is found that the observed hydrodynamics (i.e. bubble shape, departure, and deformation) are simulated very well. The comparison with high-resolution transient temperature measurements during a heating foil experiment indicates that modeling of the spatio-temporal heat sink distribution during bubble growth requires major attention. The simulation tool is employed for single bubble dynamics during flow boiling, and the agreement is excellent with published experimental data. The numerical results indicate how bulk flow velocity and wall heat transfer influence the bubble and heat transfer characteristics.

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