Experimental Study of Heat Transfer Induced by a Single Vapor Bubble Growth: Influence of Liquid Subcooling

2004 ◽  
Author(s):  
Magali Barthes
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Vapor Bubble ◽  
Bubble Growth

Numerical Analysis of Vapor Bubble Growth and Wall Heat Transfer During Flow Boiling of Water in a Microchannel

2005 ◽  
Author(s):  
Abhijit Mukherjee ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Vapor Bubble ◽  
Bubble Growth ◽  
Stokes Equations ◽  
Flow Boiling ◽  
Navier Stokes ◽  
Channel Cross Section ◽  
Wall Heat Transfer ◽  
Wall Superheat

The present study is performed to analyze the wall heat transfer mechanisms during growth of a vapor bubble inside a microchannel. The microchannel is of 200 μm square cross section and a vapor bubble begins to grow at one of the walls, with liquid coming in through the channel inlet. The complete Navier-Stokes equations along with continuity and energy equations are solved using the SIMPLER method. The liquid vapor interface is captured using the level set technique. The bubble grows rapidly due to heat transfer from the walls and soon turns into a plug filling the entire channel cross section. The average wall heat transfer at the channel walls is studied for different values of wall superheat and incoming liquid mass flux. The results show that the wall heat transfer increases with wall superheat but is almost unaffected by the liquid flow rate. The bubble growth is found to be the primary mechanism of increasing wall heat transfer as it pushes the liquid against the walls thereby influencing the thermal boundary layer development.

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.

Numerical Study of the Effect of Surface Tension on Vapor Bubble Growth During Flow Boiling in Microchannels

2006 ◽  
Author(s):  
Abhijit Mukherjee ◽  
Satish G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Surface Tension ◽  
Vapor Bubble ◽  
Bubble Growth ◽  
Stokes Equations ◽  
Numerical Study ◽  
Flow Boiling ◽  
Navier Stokes ◽  
Wall Heat Transfer ◽  
Effect Of Surface

Microchannel heat sinks typically consist of parallel channels connected through a common header. During flow boiling random temporal and spatial formation of vapor bubbles may lead to reversed flow in certain channels which causing an early CHF condition. Inside the microchannels the liquid surface tension forces is expected to play an important role and impact the vapor bubble growth and corresponding wall heat transfer. In the present study growth of a vapor bubble inside a microchannel during flow boiling is numerically studied by varying the surface tension but keeping the value of contact angle constant. The complete Navier-Stokes equations along with continuity and energy equations are solved using the SIMPLER method. The liquid-vapor interface is captured using the level set technique. The fluid properties used are of water but the surface tension value is varied systematically. The effect of surface tension on bubble growth rate and wall heat transfer is quantified. The results indicate that for the range of parameters investigated surface tension has little influence on bubble growth and wall heat transfer.

Approximate Solution for the Heat Transfer Controlled Growth of a Steadily Translating Vapor Bubble

2008 ◽  
Author(s):  
Michael Shusser
Keyword(s):  
Heat Transfer ◽  
Approximate Solution ◽  
Vapor Bubble ◽  
Bubble Growth ◽  
Constant Velocity ◽  
Thermal Boundary Layer ◽  
Bubble Radius ◽  
Controlled Growth ◽  
Flow Models ◽  
Rate Comparison

Existing analytical solution for the problem of the heat transfer controlled growth of a spherical vapor bubble moving with a constant velocity under the assumptions of a thin thermal boundary layer and potential flow results in a complicated integral equation for the bubble radius and is too unwieldy to be used in multiphase flow models. The goal of this work is to suggest an approximate solution for this problem that gives correct asymptotic behavior and yields a simpler expression for the bubble growth rate. Comparison with the exact solution showed that this way a good approximation can be obtained.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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