scholarly journals Dynamics of bubble growth during boiling at microgravity

2021 ◽  
Vol 2119 (1) ◽  
pp. 012170
Author(s):  
F Ronshin ◽  
A Sielaff ◽  
L Tadrist ◽  
P Stephan ◽  
O Kabov
Keyword(s):  
Heat Transfer ◽  
Bubble Growth ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Heated Surface ◽  
Space Station ◽  
Growth Dynamics ◽  
Special Focus ◽  
Transfer Processes ◽  
Microgravity Conditions

Abstract The purpose of this investigation is to study the mechanisms of boiling heat transfer in microgravity conditions. The RUBI (Reference mUltiscale Boiling Investigation) is an experiment where the basic phenomena of boiling heat transfer processes on a heated surface are investigated on the ISS (International Space Station). The special focus is paid to the coupling of macroscopic bubble dynamics from nucleation, growth and detachment combined with the microscopic phenomena in the thin films and micro layers on the heater, underneath the boiling bubbles. The image treatment program has been developed in order to extract the bubble volume as well as the contact angle from the experimental images. The first data of the bubble growth dynamics have been obtained and analysed.

Advances in Understanding of Pool Boiling Heat Transfer—From Earth on to Deep Space

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Vijay K. Dhir
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
Space Station ◽  
Nucleate Boiling ◽  
International Space ◽  
Pool Boiling Heat Transfer ◽  
Fundamental Understanding

In this work, the effectiveness of the numerical simulations in advancing fundamental understanding of bubble dynamics and nucleate pool boiling heat transfer is discussed. The results of numerical simulations are validated with experiments on ground, in parabolic flights and on the International Space Station (ISS). As such validation is carried out when the level of gravity is varied over seven orders of magnitude. It is shown that reduced gravity stretches the length and time scales of the process and generally leads to degradation of rate of heat transfer associated with nucleate boiling.

scholarly journals Predicting Critical Heat Flux With Multiphase CFD: 4 Years in the Making

2017 ◽  
Author(s):  
Emilio Baglietto ◽  
Etienne Demarly ◽  
Ravikishore Kommajosyula
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Bubble Dynamics ◽  
Flow Boiling ◽  
Heated Surface ◽  
Force Balance ◽  
Modeling Framework ◽  
Lift Off ◽  
Limiting Condition

Advancement in the experimental techniques have brought new insights into the microscale boiling phenomena, and provide the base for a new physical interpretation of flow boiling heat transfer. A new modeling framework in Computational Fluid Dynamics has been assembled at MIT, and aims at introducing all necessary mechanisms, and explicitly tracks: (1) the size and dynamics of the bubbles on the surface; (2) the amount of microlayer and dry area under each bubble; (3) the amount of surface area influenced by sliding bubbles; (4) the quenching of the boiling surface following a bubble departure and (5) the statistical bubble interaction on the surface. The preliminary assessment of the new framework is used to further extend the portability of the model through an improved formulation of the force balance models for bubble departure and lift-off. Starting from this improved representation at the wall, the work concentrates on the bubble dynamics and dry spot quantification on the heated surface, which governs the Critical Heat Flux (CHF) limit. A new proposition is brought forward, where Critical Heat Flux is a natural limiting condition for the heat flux partitioning on the boiling surface. The first principle based CHF is qualitatively demonstrated, and has the potential to deliver a radically new simulation technique to support the design of advanced heat transfer systems.

Thermal Bubble Dynamics Under the Effect of Acoustic Vibration

2009 ◽  
Author(s):  
Xiaopeng Qu ◽  
Huihe Qiu
Keyword(s):  
Heat Transfer ◽  
Acoustic Field ◽  
Vapor Bubble ◽  
Boiling Heat Transfer ◽  
High Speed ◽  
Bubble Dynamics ◽  
Acoustic Vibration ◽  
Micro Electro Mechanical System ◽  
Mems Technology ◽  
Enhanced Boiling

The effect of acoustic field on the dynamics of micro thermal bubble is investigated in this paper. The micro thermal bubbles were generated by a micro heater which was fabricated by standard Micro-Electro-Mechanical-System (MEMS) technology and integrated into a mini chamber. The acoustic field formed in the mini chamber was generated by a piezoelectric plate which was adhered on the top side of the chamber’s wall. The dynamics and related heat transfer induced by the micro heater generated vapor bubble with and without the existing of acoustic field were characterized by a high speed photograph system and a micro temperature sensor. Through the experiments, it was found that in two different conditions, the temperature changing induced by the micro heater generated vapor bubble was significantly different. From the analysis of the high speed photograph results, the acoustic force induced micro thermal bubble movements, such as forcibly removing, collapsing and sweeping, were the main effects of acoustic enhanced boiling heat transfer. The experimental results and theoretical analysis were helpful for understanding of the mechanisms of acoustic enhanced boiling heat transfer and development of novel micro cooling devices.

Simulation of Nucleate Boiling With Interfacial Temperature Gradients and Sharp Interface

2018 ◽  
Author(s):  
Isaac Perez-Raya ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Contact Line ◽  
Growth Rates ◽  
Bubble Growth ◽  
Heated Surface ◽  
Nucleate Boiling ◽  
Bubble Nucleation ◽  
Heat Fluxes ◽  
Temperature Gradients ◽  
Interfacial Temperature

Effective heat transfer techniques benefit the development of nuclear and fossil fuel powered steam generators, high power electronic devices, and industrial refrigeration systems. Boiling dissipates large heat fluxes while keeping a low and a constant surface temperature. However, studies of the fluid behavior surrounding the bubble and the heat transfer near the contact-line are scare due to difficulties of flow visualization, chaotic conditions, and small length scales. The preset study shows the simulation of bubble growth over a heated surface from conception to departure. The computation of mass transfer with interfacial temperature gradients leads to proper bubble growth rates. Models to include the interface sharpness uncover the dynamic and thermal interaction between the interface and the fluid. Results indicate that the nucleation of a bubble (in water at 1 atm with 6.2 K wall superheat) has an influence region of 2Db (where Db is the departure bubble diameter). In addition, results reveal a thin thermal film near the interface that increases the heat transfer at the contact-line region. Numerical bubble growth rates compare well with experimental data on single bubble nucleation.

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