Numerical Study of Marangoni Convection around a Single Vapor Bubble during Pool Boiling

2014 ◽  
Vol 624 ◽  
pp. 262-266
Author(s):  
Chun Long Xu ◽  
Yong Chao Shi ◽  
Xiao Xing Jin ◽  
Zuo Sheng Lei ◽  
Yun Bo Zhong ◽  
...  
Keyword(s):  
Vapor Bubble ◽  
Marangoni Convection ◽  
Numerical Study ◽  
Heated Surface ◽  
Nucleate Boiling ◽  
Field Method ◽  
Phase Field Method ◽  
Heated Wall ◽  
Bubble Behavior ◽  
Earth Gravity

Boiling is known to be a very efficient mode of heat transfer in earth gravity, however, in microgravity bubble behavior is different because the buoyancy effects are replaced by surface tension effects such as Marangoni convection. The modeling of nucleate boiling with the effect of Marangoni convection in 0 g is accomplished by using Phase Field Method. Numerical simulation is carried out of single nucleating vapor bubble on a heated wall with and without Marangoni convection. The results show that the flow field consists of a major vortex that recirculates colder fluid from the upper region, pulling it toward the hot surface to the point where the bubble meets the heated surface. This type of flow pattern has been observed in various experiments.

Microscale Vapor Bubble Interactions During Subcooled Nucleate Boiling on a Heated Wire

2007 ◽  
Author(s):  
Lu Zhang ◽  
David M. Christopher
Keyword(s):  
Heat Transfer ◽  
Vapor Bubble ◽  
Boiling Heat Transfer ◽  
Nucleate Boiling ◽  
Bubble Behavior ◽  
Transfer Rates ◽  
Bubble Interactions ◽  
Heated Wire ◽  
Nucleate Boiling Heat Transfer ◽  
Transfer Mechanisms

Bubbles have been observed moving along heated wires during subcooled nucleate boiling as they are driven by Marangoni convection around the bubbles. This paper presents more detailed observations of the vapor bubble interactions and moving bubble behavior during subcooled nucleate boiling on a heated microwire. The experimental results show that moving bubbles coalesce or rebound from other bubbles and that bubbles hop on the wire. These observations show how bubble interactions significantly affect nucleate boiling heat transfer rates and how Marangoni flow plays an important role in microscale nucleate boiling heat transfer mechanisms.

Microbubble Formation in Collapsing Process of a Single Vapor Bubble Injected in Subcooled Pool

2009 ◽  
Author(s):  
Ichiro Ueno ◽  
Yasusuke Hattori
Keyword(s):  
Heat Flux ◽  
Vapor Bubble ◽  
High Speed ◽  
Narrow Range ◽  
Heated Surface ◽  
Lighting System ◽  
Vapor Bubbles ◽  
Bubble Behavior ◽  
Subcooled Liquid ◽  
Boiling Process

‘Microbubble emission boiling,’ known as MEB, is a phenomenon that emerges in a narrow range of subcooled condition with a higher heat flux than critical heat flux (CHF) accompanying with microbubble emission from the heated surface. The authors focus on the condensing process of vapor bubbles in order to comprehend the mechanism of the microbubble formation and emitting processes. In order to simplify a surely complex boiling process, the authors try to extract an interaction between the vapor bubble and the subcooled bulk in a boiling phenomenon, that is, growing and collapsing processes of a vapor bubble ejected to subcooled liquid bath. Vapor bubble is produced by vapor generate system, and ejected to a bulk of saturated distilled water at a designated degree of subcooling. The degree of subcooling is varied from 0 to 50 K. The growing/collapsing of vapor bubble behavior is detected by employing a high-speed camera at frame rates up to 50,000 fps with a back-lighting system. In the present study, the process of microbubble emission as well as the process of the irrupting vapor bubbles to the subcooled bulk is compared to that in a MEB on a thin wire.

scholarly journals Numerical study on spindle positioning using phase field method

2018 ◽  
Vol 16 (1) ◽  
pp. 016005 ◽  
Author(s):  
M Akiyama ◽  
M Nonomura ◽  
A Tero ◽  
R Kobayashi
Keyword(s):  
Phase Field ◽  
Numerical Study ◽  
Field Method ◽  
Phase Field Method ◽  
Spindle Positioning

Multi-Jet Flows Underneath Small Bubble in Nucleate Boiling of Subcooled Self-Rewetting Fluid

2013 ◽  
Author(s):  
Leping Zhou ◽  
Yuanyuan Li ◽  
Longting Wei ◽  
Xiaoze Du
Keyword(s):  
High Speed ◽  
Marangoni Convection ◽  
Heated Surface ◽  
Ccd Camera ◽  
Jet Flow ◽  
Nucleate Boiling ◽  
Jet Flows ◽  
Wall Region ◽  
Heating Wire ◽  
Butanol Solution

Jet flow phenomenon is important in enhanced nucleate boiling heat transfer processes and applications. When heater sizes scale down, jet flow can be observed due to the Marangoni convection around bubbles staying on microscale heated surface. In this paper, two fluids were employed for comparing and demonstrating the effect of Marangoni convection on bubble behaviors on micro heating wire. One was ultrapure water and the other was aqueous n-butanol solution, a self-rewetting fluid. Bubble-top jet flow for water and multi-jet flows for n-butanol solution were observed around a platinum micro heating wire by high speed CCD camera. Corresponding numerical simulation proved that it is the Marangoni convection that attracts the sub-cooled water to flow from the super-heated microlayer at the bottom to the top of a stationary bubble. For n-butanol solution, however, the Marangoni convection can induce it to flow oppositely, which causes the subcooled solution to flow onto the heated surface. The simulation for the solution is in good agreement with the experiment where the subcooled liquid nears the bubble-top flow towards the bottom of bubble or the heated surface and hence the multi-jet flows occur. The multi-jet flows can sustain for a long period and cause transient chaos at the super-heated thin liquid layer near the heated surface. The temperature around the bubble presented sharp temperature gradient and the velocity in the near-wall region is almost vertical to the wall. The experimental and numerical studies on the effect of surface tension and thus Marangoni convection are crucial to the mechanisms of subcooled nucleate boiling of fluids.

Experimental and Numerical Study of the Effects of Asymmetric Micro Ratchets on Pool Boiling Performance

2013 ◽  
Author(s):  
Lance Brumfield ◽  
Sunggook Park
Keyword(s):  
High Performance ◽  
Numerical Study ◽  
Heated Surface ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Industrial Applications ◽  
Heat Fluxes ◽  
Working Fluid ◽  
High Heat Flux ◽  
Central Processing

Nucleate boiling is an attractive method for achieving high heat flux at low superheat temperatures. It is frequently used for industrial applications such as heat exchangers and is being considered to cool advanced central processing units (CPU) which produce heat fluxes on the order of 1 MW/m2 and are becoming increasingly less efficient to cool via forced conduction of air. The issues with implementing nucleate boiling as a cooling mechanism lies in the difficulty of quantifying the complex and numerous mechanisms which control the process. A comprehensive nucleate boiling model has yet to be formulated and will be required in order to safely and reliably cool high performance electronics. Spatially periodic systems with localized asymmetric surface structures (ratchets) can induce directed transport of matter (liquid/particles) in the absence of net force. It was hypothesized that ratchets may enhance pool boiling heat transfer by aiding in the removal of vapor which forms on the heated surface. Therefore, experiments on pool boiling using asymmetric micro ratchets of various geometries, with FC-72 as the working fluid, were investigated. Additionally, various numerical pool boiling simulations were performed using FLUENT to better understand the underlying physical principles behind pool boiling.

A New Method for Estimating Bubble Diameter At Different Gravity Levels for Nucleate Pool Boiling

2021 ◽  
Author(s):  
Sandipan Banerjee ◽  
Yongsheng Lian ◽  
Yang Liu ◽  
Mark Sussman
Keyword(s):  
Heat Transfer ◽  
Growth Rate ◽  
Vapor Bubble ◽  
Bubble Growth ◽  
Bubble Diameter ◽  
Nucleate Boiling ◽  
New Method ◽  
Space Applications ◽  
Earth Gravity ◽  
Micro Gravity

Abstract Nucleate boiling has significant applications in earth gravity( in industrial cooling applications) and micro-gravity conditions (in space exploration, specifically in making space applications more compact). However, the effect of gravity on the growth rate and bubble size is not yet well understood. We perform numerical simulations of nucleate boiling using an adaptive Moment-of-Fluid (MoF) method for a single vapor bubble (water or Perfluoro-n-hexane) in saturated liquid for different gravity levels. Results concerning the growth rate of the bubble, specifically the departure diameter and departure time have been provided. The MoF method has been first validated by comparing results with a theoretical solution of vapor bubble growth in super-heated liquid without any heat-transfer from the wall. Next, bubble growth rate, bubble shape and heat transfer results under earth gravity, reduced gravity and micro-gravity conditions are reported and they are in good agreement with experiments. Finally, a new method is proposed for estimating the bubble diameter at different gravity levels. This method is based on an analysis of empirical data at different gravity values and using power-series curve fitting to obtain a generalized bubble growth curve irrespective of the gravity value. This method is shown to provide a good estimate of the bubble diameter for a specific gravity value and time.

Vapor Bubble Formation, Forces, and Induced Vibration: A Review

2016 ◽  
Vol 68 (3) ◽  
Author(s):  
Manoj Kumar Gupta ◽  
Dharmendra S. Sharma ◽  
Vikas J. Lakhera
Keyword(s):  
Vapor Bubble ◽  
Flow Boiling ◽  
Heated Surface ◽  
Bubble Formation ◽  
Spherical Shape ◽  
Nucleate Boiling ◽  
Nucleation Site ◽  
Formation Mechanisms ◽  
Subcooled Boiling ◽  
Two Phase

Bubble-induced vibration has become vital during recent investigation and advancement in the area of multiphase boiling. The induced vibration phenomenon can be understood with the help of proper and detailed understanding of vapor bubble formation, growth, collapse, and interaction with the surface. The growth mechanism for the formation of bubbles under nucleate boiling conditions is theoretically investigated. This paper also discusses the dynamics of vapor bubbles during flow in subcooled boiling conditions. In the part of the vapor bubble formation, the characteristics of a bubble emerged from the heated surface at a single nucleation site along with the flow boiling phenomena have been considered for analysis. The bubble is considered to be of spherical shape and detached from a heated surface due to the formation of a microlayer of liquid. The fluid is supposed to be static far away from a vapor bubble. Using well-known models of bubble formation and detachment, equations considering various forces acting over a single bubble have been derived. These equations monitor bubble characteristics in a definite manner according to the derived differential equation for energy conservation developed for the two-phase flow system. To illustrate this phenomenon, two bubble formation mechanisms, inertia-controlled and heat transfer-controlled growth have been considered. The present investigation discusses the governing equations for the bubble growth rate, bubble size and frequency, forces, and the well-known Rayleigh's equation. Also, the vibration characteristic has been reviewed, and the two phenomena, i.e., subcooled boiling induced vibration (SBIV) and flow-induced vibration (FIV) have been discussed in brief. The present review paper aims to reveal the latest evaluation done in the area of bubble-induced vibration and to ascertain the contributions made until now as well as the solution to the upcoming issues.

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