Simulation of Single Bubble Dynamics in Nucleate Pool Boiling Using a Conservative Level Set Method

2009 ◽  
Author(s):  
Muhammad Sajid ◽  
Rachid Bennacer
Keyword(s):  
Surface Tension ◽  
Level Set ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
Heated Wall ◽  
Nucleate Pool Boiling ◽  
Vapor Interface ◽  
Level Set Function ◽  
Conservative Level Set ◽  
Liquid Vapor

Most energy conversion systems and cooling devices employ nucleate pool boiling because of its high efficiency of heat exchange. It is a liquid-vapor phase change process associated with ebullition, characterized by cyclic growth and departure of vapor bubbles from heated wall and greatly influenced by the bubble growth mechanism. Bubble dynamics is difficult to simulate due to the difficulty of tracking the liquid vapor interface without smearing it, the discontinuity in material properties due to high density ratio and the need to take surface tension into account that introduces a jump in the pressure field. This paper focuses on the accurate representation of surface tension effects on bubble dynamics in nucleate pool boiling. The complete Navier-Stokes equations are solved and liquid-vapor interface is captured using a conservative level-set technique, curvature of interface is computed using the level set function and surface tension forces are evaluated as a body force according to the continuum surface force method. This enables us to simulate flows with large density and viscosity differences, to capture the shape of the deforming interface of the bubble while maintaining good mass conservation. The ability of the model is demonstrated with the numerical example of a growing bubble.

Force Analysis of Bubble Dynamics in Flow Boiling Silicon Nanowire Microchannels

2016 ◽  
Author(s):  
Tamanna Alam ◽  
Wenming Li ◽  
Fanghao Yang ◽  
Ahmed Shehab Khan ◽  
Yan Tong ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Bubble Growth ◽  
Bubble Dynamics ◽  
Flow Boiling ◽  
Silicon Nanowire ◽  
Bubble Nucleation ◽  
Force Analysis ◽  
Vapor Interface ◽  
Liquid Vapor

In microchannel flow boiling, bubble nucleation, growth and flow regime development are highly influenced by channel cross-section and physical phenomena underlying this mechanism are far from being well-established. Relative effects of different forces acting on wall-liquid and liquid-vapor interface of a confined bubble play an important role in heat transfer performances. Therefore, fundamental investigations are necessary to develop enhanced microchannel heat transfer surfaces. Force analysis of vapor bubble dynamics in flow boiling Silicon Nanowire (SiNW) microchannels has been performed based on theoretical, experimental and visualization studies. The relative effects of different forces on flow regime, instability and heat transfer performances of flow boiling in Silicon Nanowire microchannels have been identified. Inertia, surface tension, shear, buoyancy, and evaporation momentum forces have significant importance at liquid-vapor interface as discussed earlier by several authors. However, no comparative study has been done for different surface properties till date. Detailed analyses of these forces including contact angle and bubble flow boiling characteristics have been conducted in this study. A comparative study between Silicon Nanowire and Plainwall microchannels has been performed based on force analysis in the flow boiling microchannels. In addition, force analysis during instantaneous bubble growth stage has been performed. Compared to Plainwall microchannels, enhanced surface rewetting and critical heat flux (CHF) are owing to higher surface tension force at liquid-vapor interface and Capillary dominance resulting from Silicon Nanowires. Whereas, low Weber number in Silicon Nanowire helps maintaining uniform and stable thin film and improves heat transfer performances. Moreover, force analysis during instantaneous bubble growth shows the dominance of surface tension at bubble nucleation and slug/transitional flow which resulted higher heat transfer contact area, lower thermal resistance and higher thin film evaporation. Whereas, inertia force is dominant at annular flow and it helps in bubble removal process and rewetting.

On the Dependence of Surface Tension of Liquids on the Curvature of the Liquid−Vapor Interface

2001 ◽  
Vol 105 (5) ◽  
pp. 1050-1055 ◽  
Author(s):  
Vladimir B. Fenelonov ◽  
Gennady G. Kodenyov ◽  
Vitaly G. Kostrovsky
Keyword(s):  
Surface Tension ◽  
Vapor Interface ◽  
Liquid Vapor

scholarly journals Moses Effect (Deformation of Diamagnetic Liquid/Vapor Interface by Magnetic Field): Physics and Applications

2019 ◽  
Author(s):  
Edward Bormashenko
Keyword(s):  
Magnetic Field ◽  
Surface Tension ◽  
Experimental Techniques ◽  
Magnetic Memory ◽  
Self Healing ◽  
Near Surface ◽  
Vapor Interface ◽  
Macroscopic Properties ◽  
Liquid Vapor

Deformation of the surface of diamagnetic liquid by magnetic field is called the “Moses Effect”. Physics and applications of the direct and inverse Moses effects are reviewed. Experimental techniques enabling visualization of the effects are surveyed. Impact of magnetic field on micro- and macroscopic properties of liquids is addressed. Influence of the surface tension on the shape of the near-surface dip formed in a diamagnetic liquid by magnetic field is reported. Floating of diamagnetic bodies driven by the Moses effect is treated. The effect of the “magnetic memory of water” in its relation to the Moses Effect is discussed. The dynamics of self-healing of near-surface dips due to the Moses Effect is considered.

Electrohydrodynamic effects on bubble dynamics during nucleate pool boiling under the leaky dielectric assumption

2022 ◽  
Vol 34 (1) ◽  
pp. 013606
Author(s):  
Jing-Da Yao ◽  
Kang Luo ◽  
Jian Wu ◽  
Hong-Liang Yi
Keyword(s):  
Bubble Dynamics ◽  
Pool Boiling ◽  
Nucleate Pool Boiling ◽  
Leaky Dielectric

The Role of Surfactant Adsorption Rate in Heat and Mass Transfer Enhancement in Absorption Heat Pumps

2000 ◽  
Author(s):  
Michael S. Koenig ◽  
Gershon Grossman ◽  
Khaled Gommed
Keyword(s):  
Mass Transfer ◽  
Surface Tension ◽  
Heat And Mass Transfer ◽  
Heat Pumps ◽  
Surfactant Adsorption ◽  
Relaxation Rates ◽  
Dynamic Surface ◽  
Vapor Interface ◽  
Enhanced Absorption ◽  
Liquid Vapor

Abstract The importance of heat and mass transfer additives in absorption chillers and heat pumps has been recognized for over three decades. However, a universally accepted model for the mechanisms responsible for enhanced absorption rates has yet to be proposed. The Marangoni effect — an instability arising from gradients in surface tension at the liquid-vapor interface — is generally accepted as the cause of the convective flows that enhance transfer rates. Certain surfactant additives can significantly improve absorption rates and thus reduce the overall transfer area required by a given machine. Any means available that can increase the efficiency and acceptability of absorption machines is to be welcomed, as this technology provides an alternative to vapor compression systems which is both environmentally friendly and more versatile with regards to energy sources. This study investigates the rate at which a surfactant additive adsorbs at a liquid-vapor interface. The residence time of the falling liquid solution in an absorber is quite short. An effective additive must not only reduce the surface tension of the solution; it must do so quickly enough to cause the Marangoni instability within the short absorption process time. The entrance region of an absorber features a freshly exposed interface at which no surfactant has adsorbed. A numerical model is used to analyze surfactant relaxation rates in a static film of additive-laced solution. Kinetic parameters for the combination of the working pair LiBr-H2O and the additive 2-ethyl-1-hexanol are derived from data in the literature for static and dynamic surface tension measurements. Bulk, interfacial and boundary parameters influencing relaxation rates are discussed for surfactant adsorption occurring in the absence of absorption, as well as for concurrent adsorption and stable vapor absorption. Initial solution conditions and absorption driving force are shown to impact the potential for instability in the effect they have on the rate of interfacial additive adsorption.

Sign in / Sign up

Export Citation Format

Share Document