scholarly journals Numerical Investigation on Single Bubble and Multiple Bubbles Growth and Heat Transfer During Flow Boiling in A Microchannel Using the VOSET Method

2019 ◽  
Vol 31 (4) ◽  
pp. 381-393 ◽  
Author(s):  
Kaikai Guo ◽  
Huixiong Li ◽  
Yuan Feng ◽  
Jianfu Zhao ◽  
Tai Wang
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Flow Boiling ◽  
Single Bubble ◽  
Multiple Bubbles

Numerical investigation of thermal performance of key components of electric vehicles using nucleate boiling

2021 ◽  
pp. 1-33
Author(s):  
Shyamkumar P.I. ◽  
Suneet Singh ◽  
Atul Srivastava ◽  
Milan Visaria
Keyword(s):  
Heat Transfer ◽  
Bubble Dynamics ◽  
Cooling System ◽  
Flow Boiling ◽  
Rectangular Channel ◽  
Nucleate Boiling ◽  
Single Bubble ◽  
Scavenging Effect ◽  
Multiple Bubbles ◽  
Straight Flow

Abstract An efficient thermal management system is desirable for improving the performance of key components of electric vehicle (EV), such as battery packs and Insulated-Gate Bipolar Transistors (IGBTs). This paper investigates the application of single bubble nucleate boiling heat transfer in battery and IGBT component cooling pack. A semi mechanistic flow boiling model, which combines four main sub-models i.e. phase change model, micro-region model, Marangoni model, and contact angle model is developed to get the insight of various subprocesses like bubble inception, growth, departure, scavenging effect while the bubble departs and condensation. For model validation, simulations are carried out for single bubble flow boiling in a vertical rectangular channel and compared against the experimental data available in the literature. Thereafter, simulations are carried out for the battery and IGBT cooling pack to understand the physical phenomena associated with nucleate boiling in such systems. The choice of a single vapor bubble vis-à-vis multiple bubbles has been based on the objective of validating the developed numerical model. An enhancement of ∼30% in heat transfer is achieved for both battery and IGBT components when the system is subjected to a nucleate boiling cooling regime as compared to a conventional single-phase convection cooling system. Nusselt number variation due to the single bubble movement along the coolant path is studied in detail for both serpentine-shaped cooling path in a battery and straight flow path in an IGBT. Moreover, the influence of Reynolds number over bubble dynamics is analyzed.

Numerical Investigation of Flow Boiling in a Manifold Microchannel Heat Sink With Conjugate Heat Transfer

2019 ◽  
Author(s):  
Zhichuan Sun ◽  
Yang Luo ◽  
Junye Li ◽  
Wei Li ◽  
Jingzhi Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Investigation ◽  
Heat Sink ◽  
Conjugate Heat Transfer ◽  
Flow Boiling ◽  
High Heat Flux ◽  
Microchannel Heat Sink ◽  
Two Phase ◽  
Boiling Process ◽  
Manifold Microchannel

Abstract The manifold microchannel heat sink receives an increasing number of attention lately due to its high heat flux dissipation. Numerical investigation of boiling phenomena in manifold microchannel (MMC) heat sinks remains a challenge due to the complexity of fluid route and the limitation of numerical accuracy. In this study, a computational fluid dynamics (CFD) approach including subcooled two-phase flow boiling process and conjugate heat transfer effect is performed using a MMC unit cell model. Different from steady-state single phase prediction in MMC heat sink, this type of modeling allows for the transient simulation for two-phase interface evolution during the boiling process. A validation case is conducted to validate the heat transfer phenomenon among three phases. Besides, this model is used for the assessment of the manifold dimensions in terms of inlet and outlet widths at the mass flux of 1300 kg/m2·s. With different ratios of inlet-to-outlet area, the thermal resistances remain nearly stable.

Condensation Heat Transfer Model: A Comparison Study of Condensation Rate Between a Single Bubble and Multiple Rising Bubbles

2021 ◽  
Author(s):  
Fadi Alnaimat ◽  
Omar Alhammadi ◽  
Bobby Mathew
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Thermal Energy ◽  
Transfer Rate ◽  
Single Bubble ◽  
Condensation Rate ◽  
Experiment Data ◽  
Multiple Bubbles ◽  
Total Thermal Energy ◽  
Good Agreement

Abstract The main objective of this work is to develop a numerical model to analyze heat transfer and condensation of a rising spherical bubble. The model included the bubble shrinkage during condensation, which can be utilized to analyze the bubble’s total energy loss, raising velocity, and condensation rate of a single bubble compared to multiple bubbles with the same total thermal energy. The equations of motion, heat, and mass transfer were developed. The model results were verified with the bubble condensation experiment data in the literature, in which they exhibited a good agreement. For the validation, the model results were compared with bubble condensation experiment data in the literature, which showed a good agreement with the experimental results. The dynamic term of the model is developed using the force balance on a gravity-driven bubble, including hydrodynamic drag force and gravity/buoyancy force, which acting with and against the bubble’s motion direction. For the thermal part of the model, a condensation correlation has been adapted to represent the Nusselt number as a function of Reynolds number (Re), Jakob number (Ja), and Prandtl number (Pr). A MATLAB code is developed in order to calculate the instantaneous velocity, the radius, and the mass loss of the vapor bubble in each time step. Moreover, the fundamental behavior for a single bubble and multiple bubbles was investigated in various initial conditions under the same total thermal energy. The effects of the initial bubble radius and the temperature difference between the liquid and vapor phases were analyzed for both scenarios in order to examine the condensation rate. It was found that the thermal behavior of the condensing bubble can be improved by forcing the bubble to collapse into sub bubbles, which will increase the total interfacial area and the rising velocity. Farther, due to generated sub bubbles, the resultant velocity increased the turbulency and the heat transfer rate accordingly. This study can lead to improve the heat transfer rate and allow for more intensive research to enhance the condensation rate.

A Numerical Study of Single Bubble Dynamics During Flow Boiling

2004 ◽  
Author(s):  
Ding Li ◽  
Vijay K. Dhir
Keyword(s):  
Heat Transfer ◽  
Bubble Dynamics ◽  
Numerical Study ◽  
Flow Boiling ◽  
Forced Flow ◽  
Single Bubble ◽  
Horizontal Line ◽  
Vapor Interface ◽  
Single Bubble Dynamics ◽  
Liquid Vapor

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.

Computational Study of Saturated Flow Boiling Within a Microchannel in the Slug Flow Regime

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Mirco Magnini ◽  
John R. Thome
Keyword(s):  
Heat Transfer ◽  
Slug Flow ◽  
Flow Boiling ◽  
Periodic Regime ◽  
Liquid Slug ◽  
Modeling Framework ◽  
Saturated Flow ◽  
Bubble Liquid ◽  
Continuous Stream ◽  
Multiple Bubbles

This paper presents a fundamental study of the flow dynamics and heat transfer induced by a slug flow under saturated flow boiling in a circular microchannel. Numerical simulations are carried out by utilizing the commercial CFD solver ansys fluent v. 14.5, with its built-in volume of fluid (VOF) method to advect the interface, which was improved here by implementing self-developed functions to model the phase change and the surface tension force. A continuous stream of bubbles is generated (by additional user-defined functions) by patching vapor bubbles at the channel upstream with a constant generation frequency. This modeling framework can capture the essential features of heat transfer in slug flows for a continuous stream of bubbles which are here investigated in detail, e.g., the mutual influence among the growing bubbles, the fluid mechanics in the liquid slug trapped between two consecutive bubbles, the effect of bubble acceleration on the thickness of the thin liquid film trapped against the channel wall and on other bubbles, and the transient growth of the heat transfer coefficient and then its periodic variation at the terminal steady-periodic regime, which is reached after the transit of a few bubble–liquid slug pairs. Furthermore, the results for a continuous stream of bubbles are found to be quite different than that of a single bubble, emphasizing the importance of modeling multiple bubbles to study this process. Finally, the outcomes of this analysis are utilized to advance a theoretical model for heat transfer in microchannel slug flow that best reproduces the present simulation data.

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

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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