Experimental Study of Bubble Dynamics on a Micro Heater Induced by Pulse Heating

2004 ◽  
Vol 126 (2) ◽  
pp. 259-271 ◽  
Author(s):  
Y. Hong ◽  
N. Ashgriz ◽  
J. Andrews
Keyword(s):  
Experimental Study ◽  
Bubble Growth ◽  
Bubble Dynamics ◽  
Pulse Heating ◽  
Deionized Water ◽  
Nucleation Theory ◽  
Electric Pulses ◽  
Pressure Profiles ◽  
Rapid Formation ◽  
Resistive Heater

An experimental investigation of the rapid formation and collapse of bubbles formed on a micro heater (25×80 μm2) is presented. Short electric pulses in the range of 1 μs to 4 μs are applied to the resistive heater, which is immersed in deionized water and generates a heat flux of more than 750 MW/m2. A stroboscopic technique with a time resolution of 30 ns and spatial resolution of 2 μm was used to capture the dynamics of the bubble growth and collapse. From the nucleation theory, the nucleation temperatures are close to the kinetic limit of superheat and weakly depends on the heating rate. The velocity, acceleration, and the pressure profiles after the vapor sheet formation are presented.

Numerical Study of Bubble Growth on a Micro-Finned Surface

2011 ◽  
Author(s):  
Woorim Lee ◽  
Gihun Son
Keyword(s):  
Heat Transfer ◽  
Bubble Growth ◽  
Bubble Dynamics ◽  
Numerical Study ◽  
Removal Rate ◽  
Bubble Formation ◽  
Experimental Studies ◽  
Nucleate Boiling ◽  
Finned Surface ◽  
Fin Spacing

Bubble growth on a micro-finned surface, which can be used in enhancing boiling heat transfer, is numerically investigated by solving the conservation equations of mass, momentum, and energy. The bubble deformation or the liquid-vapor interface is determined by the sharp-interface level-set method, which is modified to include the effect of phase change and to treat the contact angle and the evaporative heat flux from the liquid microlayer on an immersed solid surface of a microfin. The numerical method is applied to clarify bubble growth and heat transfer characteristics on a surface including fin and cavity during nucleate boiling which have not been provided from the previous experimental studies. The effects of single fin, fin-cavity distance, and fin-fin spacing on the bubble dynamics are investigated. The micro-fin is found to affect the activation of cavity. The fin-cavity configuration is found to determine the bubble formation in a cavity. The vapor removal rate is also observed to significantly depend on the fin-fin spacing.

Review on Bubble Dynamics in Microchannel Heat Sink

2019 ◽  
Author(s):  
Sambhaji T. Kadam ◽  
Ibrahim Hassan ◽  
Ritunesh Kumar ◽  
Aziz Rahman
Keyword(s):  
Bubble Growth ◽  
Bubble Dynamics ◽  
Growth Models ◽  
Flow Boiling ◽  
Nucleation Site ◽  
Bubble Nucleation ◽  
Operating Conditions ◽  
Geometrical Parameters ◽  
Detailed Knowledge ◽  
Diffusion Controlled

Abstract Inception of the boiling, in pool or flow boiling, is the formation of the vapour bubble at active nucleation site. The bubble dynamics plays an important role in the boiling process. It is critical as it unfolds many facets especially when channel size is reduced to submicron. The detailed knowledge of the bubble dynamics is helpful in establishing the thermal and hydraulic flow behaviour in microchannel. In this paper, the bubble dynamics which include bubble nucleation at nucleation site, its growth, departure and motion along the flow in a microchannel are discussed in details. Different models are developed for the critical cavity radius are compiled and observed that they show large variation when compare. The bubble growth models are compiled and concluded that a development of more generalized bubble growth model is necessary to account for the inertia controlled and thermal diffusion controlled regions. The bubble at the nucleation site in a microchannel grows under the influence of various forces such as surface tension, inertia, shear, gravitational and evaporation momentum. Parametric variations of these forces are critically studied and reckoned that the slope of these forces seems to be reduced beyond 500 μm. Eventually, possible impact of the various factors such as operating conditions, geometrical parameters, and thermophysical properties of fluid on bubble dynamics in microchannel has been reported.

Experimental Study on Flow Boiling of Deionized Water in a Horizontal Long Small Channel

2018 ◽  
Vol 27 (2) ◽  
pp. 157-166 ◽  
Author(s):  
Qian Huang ◽  
Li Jia ◽  
Chao Dang ◽  
Lixin Yang
Keyword(s):  
Experimental Study ◽  
Flow Boiling ◽  
Deionized Water ◽  
Small Channel

Simulation of bubble growth and collapse in linear and pom-pom polymers

e-Polymers ◽  
2002 ◽  
Vol 2 (1) ◽  
Author(s):  
Uday S. Agarwal
Keyword(s):  
Bubble Growth ◽  
Bubble Dynamics ◽  
Polymer Melt ◽  
Integral Form ◽  
Polymer Chains ◽  
Bubble Collapse ◽  
Flow Strength ◽  
Branch Lengths ◽  
Programming Effort ◽  
Viscoelastic Liquids

AbstractExisting approaches to simulate the bubble growth/collapse in viscoelastic liquids use the integral form of a constitutive equation, that can additionally be analytically integrated over the radial domain. Here we represent the process by a system of simultaneous partial differential equations, with fixed and finite boundaries. This enables a direct computer implementation with commercially available software, with little additional programming effort. The involved co-ordinate transformation preferably does not correspond to the material co-ordinates. The surrounding liquid can be simulated as being a finite film or of infinite extent, with simply a change in one computational parameter. We simulate hydrodynamically induced bubble dynamics in viscolelastic liquids, and estimate the flow strength (elongational strain rate) and its possible role in flow induced scission of polymer chains in liquids experiencing bubble collapse. Calculations are also performed to evaluate the influence of backbone and branch lengths when the surrounding fluid is a branched polymer melt, using the pom-pom model to describe the rheological behavior.

scholarly journals A new bubble dynamics model to study bubble growth, deformation, and coalescence

2014 ◽  
Vol 119 (1) ◽  
pp. 216-239 ◽  
Author(s):  
C. Huber ◽  
Y. Su ◽  
C. T. Nguyen ◽  
A. Parmigiani ◽  
H. M. Gonnermann ◽  
...  
Keyword(s):  
Bubble Growth ◽  
Bubble Dynamics ◽  
Dynamics Model

An Experimental Study of Cavitation in a Mixed Flow Pump Impeller

1960 ◽  
Vol 82 (4) ◽  
pp. 929-940 ◽  
Author(s):  
G. M. Wood ◽  
J. S. Murphy ◽  
J. Farquhar
Keyword(s):  
Experimental Study ◽  
Static Pressure ◽  
Hydraulic Performance ◽  
Mixed Flow ◽  
Pump Impeller ◽  
Flow Models ◽  
Cavitation Performance ◽  
Pressure Profiles ◽  
Closed Water ◽  
Flow Pump

A mixed flow impeller design was tested with six, five, and four vanes in a closed water loop to study the effects of cavitation on hydraulic performance and the results were compared with the work of other investigators. Two idealized flow models for incipient cavitation were derived to illustrate limits of cavitation design. It was found that both vane blockage and solidity effects are important when designing for optimum cavitation performance. Data showing incidence and speed effects plus the tip static pressure profiles in cavitating and noncavitating flow are also presented.

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