Transient boiling flow instabilities in a multi-channel upflow system

1977 ◽  
Vol 10 (3) ◽  
pp. 175-188 ◽  
Author(s):  
S. Kakaç ◽  
T. N. Veziroğlu ◽  
N. Özboya ◽  
S. S. Lee
Keyword(s):  
Flow Instabilities ◽  
Boiling Flow ◽  
Transient Boiling

Transient boiling flow in 5 × 5 rod bundle under non-uniform rapid heating

2018 ◽  
Vol 340 ◽  
pp. 447-456 ◽  
Author(s):  
Hiroki Takiguchi ◽  
Masahiro Furuya ◽  
Takahiro Arai ◽  
Kenetsu Shirakawa
Keyword(s):  
Rapid Heating ◽  
Rod Bundle ◽  
Boiling Flow ◽  
Transient Boiling

Active Flow Instability Control for Transient Two-Phase Electronics Cooling

2010 ◽  
Author(s):  
Tie Jun Zhang ◽  
Yoav Peles ◽  
John T. Wen ◽  
Michael K. Jensen
Keyword(s):  
Active Control ◽  
Flow Instability ◽  
Cooling System ◽  
Flow Instabilities ◽  
Future Research ◽  
Two Phase ◽  
Control Schemes ◽  
Boiling Flow ◽  
Flow Oscillations ◽  
Two Phase Cooling

Because of increasing power densities, refrigeration systems are being explored for two-phase cooling of ultra high power electronic components. Flow instabilities are potential problems in any two-phase refrigeration cooling system especially in transient applications. Oscillatory two-phase flow in a boiling channel can trigger transition to the critical heat flux (CHF). Active control methods can help better dynamic thermal management of electronic systems, even though transient two-phase boiling flow mechanisms are complicated. This paper presents a framework for the transient analysis and active control of pressure-drop flow instabilities under varying imposed heat loads. The first part of the paper is to study the external effects on boiling flow characteristics and the boiling oscillatory flow responses to transient heat load changes. Then based on the theoretical analysis of boiling flow oscillations, a set of active control schemes are developed and studied to suppress flow oscillations and, therefore, to increase the CHF. With the available control devices (i.e., inlet valve and supply pump), different active control schemes are studied to improve the transient two-phase cooling performance. Finally, a discussion is included to address potential future research.

Suppression of Two-Phase Flow Instabilities in Parallel Microchannels by Using Synthetic Jets

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Ruixian Fang ◽  
Jamil A. Khan
Keyword(s):  
Two Phase Flow ◽  
Flow Boiling ◽  
Synthetic Jets ◽  
Flow Instabilities ◽  
Phase Flow ◽  
Microchannel Flow ◽  
Two Phase ◽  
Boiling Flow ◽  
Parallel Microchannels ◽  
Flow Reversals

Two-phase flow instabilities in microchannels exhibit pressure and temperature fluctuations with different frequencies and amplitudes. An active way to suppress the dynamic instabilities in the boiling microchannels is to introduce synthetic jets into the channel fluid. Thus, the bubbles can be condensed before they clog the channel and expand upstream causing flow reversal. The present work experimentally investigated the effects of synthetic jets on microchannel flow boiling. An array of synthetic jets was introduced into the microchannel flow. The strength and frequency of the jets were controlled by changing the driving signals of the piezoelectric driven jet actuator. It is found that the bubbles were effectively condensed inside the jet cavity. The boiling flow reversals were notably delayed by the synthetic jets. Meanwhile, the pressure fluctuation amplitudes were suppressed to some extent. It was also observed that synthetic jets can help to uniformize the heat sink temperature distribution.

Numerical Solution for Transient Conjugate Two-Phase Heat Transfer With Heat Generation in the Pipe Wall

2002 ◽  
Vol 124 (6) ◽  
pp. 1213-1218 ◽  
Author(s):  
Yuri V. Fairuzov ◽  
Hector Arvizu
Keyword(s):  
Heat Transfer ◽  
Numerical Solution ◽  
Heat Generation ◽  
Two Phase ◽  
Convective Boiling ◽  
Wall Superheat ◽  
Boiling Flow ◽  
Rigorous Model ◽  
Two Phase Heat Transfer ◽  
Transient Boiling

A method developed earlier for modeling conjugate two-phase heat transfer in flashing flows was used to obtain a numerical solution for transient boiling flow in heated pipes or channels. Two criteria of applicability of the solution obtained were proposed and numerically tested using a more rigorous model, which accounts for the effects of heat conduction with heat generation in the wall and forced convective boiling. The solution obtained provides a simple and reliable alternative to more rigorous methods for modeling transient two-phase flow in heated channels when the material of the wall bounding the flow has a high thermal conductivity and the wall superheat is small.

Sign in / Sign up

Export Citation Format

Share Document