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.

Study of Lateral Merger of Vapor Bubbles During Nucleate Pool Boiling

2004 ◽  
Vol 126 (6) ◽  
pp. 1023-1039 ◽  
Author(s):  
A. Mukherjee ◽  
V. K. Dhir
Keyword(s):  
Heat Transfer ◽  
Bubble Dynamics ◽  
Nucleate Boiling ◽  
Three Dimensions ◽  
Navier Stokes ◽  
Wall Heat Transfer ◽  
Navier Stokes Equation ◽  
Simple Method ◽  
Multiple Bubbles ◽  
Energy Equations

In the present work the bubble dynamics and heat transfer associated with lateral bubble merger during transition from partial to fully developed nucleate boiling is studied numerically. Complete Navier–Stokes equation in three dimensions along with the continuity and energy equations are solved using the SIMPLE method. The liquid vapor interface is captured using the Level-Set technique. Calculations are carried out for multiple bubble mergers in a line and also in a plane and the bubble dynamics and wall heat transfer are compared to that for a single bubble. The results show that merger of multiple bubbles significantly increases the overall wall heat transfer. This enhanced wall heat transfer is caused by trapping of liquid layer between the bubble bases during merger and by drawing of cooler liquid towards the wall during contraction after merger. Good agreement with data from experiments is found in bubble growth rate and bubble shapes obtained from numerical simulations.

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.

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.

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.

Study on Subcooled-Forced Flow Boiling Heat Transfer and Critical Heat Flux of Solid-Water Two-Phase Mixture

1999 ◽  
Author(s):  
Yasuo Koizumi ◽  
Hiroyasu Ohtake ◽  
Manabu Mochizuki
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Critical Heat Flux ◽  
Liquid Layer ◽  
Boiling Heat Transfer ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Forced Flow ◽  
Superheated Liquid ◽  
Flow Boiling Heat Transfer

Abstract The effect of solid particle introduction on subcooled-forced flow boiling heat transfer and a critical heat flux was examined experimentally. In the experiment, glass beads of 0.6 mm diameter were mixed in subcooled water. Experiments were conducted in a range of the subcooling of 40 K, a velocity of 0.17–6.7 m/s, a volumetric particle ratio of 0–17%. When particles were introduced, the growth of a superheated liquid layer near a heat trasnsfer surface seemed to be suppressed and the onset of nucleate boiling was delayed. The particles promoted the condensation of bubbles on the heat transfer surface, which shifted the initiation of a net vapor generation to a high heat flux region. Boiling heat trasnfer was augmented by the particle introduction. The suppression of the growth of the superheated liquid layer and the promotion of bubble condensation and dissipation by the particles seemed to contribute that heat transfer augmentation. The wall superheat at the critical heat flux was elevated by the particle introduction and the critical heat flux itself was also enhanced. However, the degree of the critical heat flux improvement was not drastic.

Study on onset of nucleate boiling with screw tube for fusion reactor application

2021 ◽  
Author(s):  
Ji Hwan Lim ◽  
Minkyu Park
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
High Heat ◽  
Transfer Mechanism ◽  
High Heat Flux ◽  
Heat Transfer Mechanism ◽  
System Parameters ◽  
Smooth Tubes

Abstract The onset of nucleate boiling (ONB) is the point at which the heat transfer mechanism in fluids changes and is one of the thermo-hydraulic factors that must be considered when establishing a cooling system operation strategy. Because the high heat flux of several MW/m2, which is loaded within a tokamak, is applied under a one-side heating condition, it is necessary to determine a correlative relation that can predict ONB under special heating conditions. In this study, the ONB of a one-side-heated screw tube was experimentally analyzed via a subcooled flow boiling experiment. The helical nut structure of the screw tube flow path wall allows for improved heat transfer performance relative to smooth tubes, providing a screw tube with a 53.98% higher ONB than a smooth tube. The effects of the system parameters on the ONB heat flux were analyzed based on the changes in the heat transfer mechanism, with the results indicating that the flow rate and degree of subcooling are proportional to the ONB heat flux because increasing these factors improves the forced convection heat transfer and increases the condensation rate, respectively. However, it was observed that the liquid surface tension and latent heat decrease as the pressure increases, leading to a decrease in the ONB heat flux. An evaluation of the predictive performance of existing ONB correlations revealed that most have high error rates because they were developed based on ONB experiments on micro-channels or smooth tubes and not under one-side high heat load conditions. To address this, we used dimensional analysis based on Python code to develop new ONB correlations that reflect the influence of system parameters.

scholarly journals Effect of Metal Foam Insert Configurations on Flow Boiling Heat Transfer and Pressure Drop in a Rectangular Channel

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4617
Author(s):  
Sanghyun Nam ◽  
Dae Yeon Kim ◽  
Youngwoo Kim ◽  
Kyung Chun Kim
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Mass Flux ◽  
Test Section ◽  
Boiling Heat Transfer ◽  
Metal Foam ◽  
Flow Boiling ◽  
Rectangular Channel ◽  
Saturation Pressure ◽  
Two Phase

Heat transfer under flow boiling is better in a rectangular channel filled with open-cell metal foam than in an empty channel, but the high pressure drop is a drawback of the empty channel method. In this study, various types of metal foam insert configurations were tested to reduce the pressure drop while maintaining high heat transfer. Specifically, we measured the boiling heat transfer and pressure drop of a two-phase vertical upward flow of R245fa inside a channel. To measure the pressure and temperature differences of the metal foam, differential pressure transducers and T-type thermocouples were used at both ends of the test section. While the saturation pressure was kept constant at 5.9 bar, the steam quality at the inlet of the test section was changed from 0.05 to 0.99. The channel height, moreover, was 3 mm, and the mass flux ranged from 133 to 300 kg/m2s. The two-phase flow characteristics were observed through a high-speed visualization experiment. Heat transfer tended to increase with the mean vapor quality, and, as expected, the fully filled metal foam channel offered the highest thermal performance. The streamwise insert pattern model had the lowest heat transfer at a low mass flux. However, at a higher mass flux, the three different insert models presented almost the same heat transfer coefficients. We found that the streamwise pattern model had a very low pressure drop compared to that of the spanwise pattern models. The goodness factors of the flow area and the core volume of the streamwise patterned model were higher than those of the full-filled metal foam channel.

Calcium Carbonate Scale Formation During Subcooled Flow Boiling

1997 ◽  
Vol 119 (4) ◽  
pp. 767-775 ◽  
Author(s):  
S. H. Najibi ◽  
H. Mu¨ller-Steinhagen ◽  
M. Jamialahmadi
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Calcium Carbonate ◽  
Flow Boiling ◽  
Fluid Velocity ◽  
Nucleate Boiling ◽  
Operating Conditions ◽  
Initial Surface ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow

Scale deposition on the heat transfer surfaces from water containing dissolved salts considerably reduces fuel economy and performance of the heat transfer equipment. In general, this problem is more serious during nucleate boiling due to the mechanisms of bubble formation and detachment. In this study, a large number of experiments were performed to determine the effect of fluid velocity, initial surface temperature, and bulk concentration on the rate of calcium carbonate deposition on heat transfer surfaces during subcooled flow boiling. A physically sound prediction model for the deposition process under these operating conditions has been developed which predicts the experimental data with good accuracy. Two previously published models are also discussed and used to predict the experimental data.

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