scholarly journals Flow Patterns, Void Fraction, Pressure Drop, and Convective Heat Transfer in Gas-Liquid Two Phase Flow in Various Pipe Inclinations

2018 ◽  
Author(s):  
Afshin J. Ghajar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Convective Heat Transfer ◽  
Void Fraction ◽  
Convective Heat ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2004 ◽  
Vol 126 (3) ◽  
pp. 288-300 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406×2.032mm2 cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Features unique to two-phase micro-channel flow were identified and employed to validate key assumptions of an annular flow boiling model that was previously developed to predict pressure drop and heat transfer in two-phase micro-channel heat sinks. This earlier model was modified based on new findings from the adiabatic two-phase flow study. The modified model shows good agreement with experimental data for water-cooled heat sinks.

Void Fraction, Pressure Drop, and Flow Pattern Behavior for Two-Phase Non-Newtonian Slug Flow

2021 ◽  
Author(s):  
Faraj Ben Rajeb ◽  
Syed Imtiaz ◽  
Yan Zhang ◽  
Amer Aborig ◽  
Mohamed M. Awad ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Flow Pattern ◽  
Flow Regime ◽  
Void Fraction ◽  
Slug Flow ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Intermittent Flow ◽  
Phase Flow ◽  
Two Phase

Abstract Slug flow is one of the most common flow patterns in non-Newtonian two-phase flow in pipes. It is a very common occurrence in gas-liquid two-phase flow in the pipe. Usually, it is an unfavorable flow pattern due to its unsteady nature, intermittency as well as high pressure drop. The differences between slug flow and elongated bubble flow are not clear because usually these two types of flow combined under one flow category. In general, these two-phase flow regimes are commonly defined as intermittent flow. In the present study, pressure gradient, and wave behavior in slug flow have been investigated depending on experimental work. In addition, void fraction has been estimated regarding available superficial liquid and gas velocities. The experimental records of superficial velocities of gas and liquid for slug flow and other flow patterns is used to create flow regime map for the gas non-Newtonian flow system. The effect of investigated flow regime velocities for non-Newtonian/gas flow on pressure drop and void fraction is reported. Pressure drop has been discovered to be reduced in slug flow more than other flow patterns due to high shear thinning behavior.

CONVECTIVE HEAT TRANSFER OF AN IMPINGING OIL JET BETWEEN A TWO-PHASE FLOW AND A HOT SURFACE

2012 ◽  
Vol 22 (3) ◽  
pp. 185-205
Author(s):  
Ludovic Osmar ◽  
S. Vincent ◽  
J.-P. Caltagirone ◽  
David Reungoat ◽  
G. Mermaz-Rollet
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Oil Jet ◽  
Hot Surface

Validation of a General Heat Transfer Correlation for Non-Boiling Two-Phase Flow With Different Flow Patterns and Pipe Inclination Angles

2007 ◽  
Author(s):  
Clement C. Tang ◽  
Afshin J. Ghajar
Keyword(s):  
Heat Transfer ◽  
Void Fraction ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Heat Transfer Correlation ◽  
Two Phase ◽  
Transfer Data ◽  
Inclination Angles ◽  
Data Points

A general heat transfer correlation for non-boiling gas-liquid two-phase flow with different flow patterns and inclination angles was developed. To verify the correlation, local heat transfer coefficients and flow parameters were measured for air-water flow in a pipe for the horizontal and slightly upward inclined (2°, 5°, and 7°) positions, and all the flow patterns in the entire flow map. The test section was a 27.9 mm stainless steel pipe with a length to diameter ratio of 95. A total of 763 data points were collected for horizontal and slightly upward inclined positions by carefully coordinating the liquid and gas superficial Reynolds number combinations. The heat transfer data were collected under a uniform wall heat flux boundary condition ranging from about 1800 to 10900 W/m2. The superficial Reynolds numbers ranged from about 740 to 26000 for water and from about 560 to 48000 for air. The general heat transfer correlation was validated with the 763 data points that were experimentally collected. The validation confirmed the robustness of the general two-phase heat transfer correlation to adequately predict heat transfer data for various flow patterns and inclination angles. The accuracy of the correlation to correlate the experimental data was further explored by applying various available void fraction correlations. The performance of the correlation when applied with the different void fraction correlations were compared and appropriate recommendations are made.

Radiative-convective heat transfer for high-temperature two-phase flow around bodies

1993 ◽  
Vol 64 (3) ◽  
pp. 239-242
Author(s):  
V. E. Abaltusov ◽  
N. N. Alekseenko ◽  
V. F. Dementiev ◽  
T. N. Nemova
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase
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