Modified Model for Improved Flow Regime Prediction in Internally-Grooved Tubes

2013 ◽  
Author(s):  
Darin J. Sharar ◽  
Nicholas R. Jankowski ◽  
Avram Bar-Cohen
Keyword(s):  
Flow Regime ◽  
Performance Improvement ◽  
Annular Flow ◽  
Tube Flow ◽  
Two Phase ◽  
Modified Model ◽  
Transition Criteria ◽  
Two Phase Heat Transfer ◽  
Regime Map ◽  
Flow Regime Map

The absence of phenomenological insights and accurate flow regime models makes it difficult to predict the improved effectiveness of internally-grooved tubes for two-phase heat transfer. A re-interpretation of available data and flow regime maps is used to suggest that performance improvement is a result of early transition to Annular flow. A modified flow regime map, with a newly-developed Stratified-Wavy to Annular transition criteria for internally-grooved tubes, is shown to increase regime prediction accuracy by 27% relative to the traditional, smooth tube flow regime prediction.

On the Application of Macro-Pipe Two-Phase Heat Transfer Correlations and Flow Regime Maps to Mini-Channels

2006 ◽  
Author(s):  
Avram Bar-Cohen ◽  
Ilai Sher ◽  
Emil Rahim
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flow Regime ◽  
Annular Flow ◽  
Negative Slope ◽  
Two Phase ◽  
Heat Transfer Correlations ◽  
Two Phase Heat Transfer ◽  
Flow Regime Maps

The present study is aimed at evaluating the ability of conventional “macro-pipe” correlations and regime transitions to predict the two-phase thermofluid characteristics of mini-channel cold plates. Use is made of the Taitel-Dukler flow regime maps, seven classical heat transfer coefficient correlations and two dryout predictions. The vast majority of the mini-channel two-phase heat-transfer data, taken from the literature, is predicted to fall in the annular regime, in agreement with the reported observations. A characteristic heat transfer coefficient locus has been identified, with a positive slope following the transition from Intermittent to Annular flow and a negative slope following the onset of partial dryout at higher qualities. While the classical two-phase heat transfer correlations are generally capable of providing good agreement with the low-quality annular flow data the quality at which partial dryout occurs and the ensuing heat transfer rates are not predictable by the available macro-pipe correlations.

Electrohydrodynamic atomization two-phase flow regime map for liquid hydrocarbon under pulsed electric fields with co-gas flow

2008 ◽  
Vol 66 (1-2) ◽  
pp. 94-98 ◽  
Author(s):  
J.S. Chang ◽  
C. Ayrault ◽  
D. Brocilo ◽  
D. Ewing ◽  
G.D. Harvel ◽  
...  
Keyword(s):  
Flow Regime ◽  
Electric Fields ◽  
Gas Flow ◽  
Pulsed Electric Fields ◽  
Liquid Hydrocarbon ◽  
Phase Flow ◽  
Two Phase ◽  
Regime Map ◽  
Flow Regime Map ◽  
Co Gas

Experimental Study of Flow Patterns and Regimes of Condensation in Horizontal Three-Dimensional Micro-Fin Tubes

2003 ◽  
Author(s):  
Qinghua Chen ◽  
R. S. Amano ◽  
Mingdao Xin
Keyword(s):  
Flow Regime ◽  
Annular Flow ◽  
Plug Flow ◽  
Three Dimensional ◽  
Flow Patterns ◽  
Smooth Tube ◽  
Flow Transition ◽  
Regime Map ◽  
Fin Tubes ◽  
Flow Regime Map

During condensation of R134a the flow patterns inside two three-dimensional (3-D) micro-fin tubes with different fin geometries were investigated. The flow patterns and their transitions were visibly observed and recorded. The experimental findings revealed the following results: a comparison of the condensation flow patterns in the 3-D microfin tubes with those in smooth tubes revealed no qualitative differences. The mist flow and the mist-annular flow that appeared in the smooth tube entrance region were not observed in 3-D micro-fin tubes. In the maps of the Mandhane flow regime and the Soliman flow regime, the area of annular flow region of the 3-D micro-fin tube extends towards lower Fr number range in the Soliman map and smaller vapor velocity range in the Mandhane map when compared with that of a smooth tube. The criterion of the flow regime transition between the annular flow and wavy flow decreases from Fr = 7 to Fr = 2 in the Soliman flow regime map. However, no significant effect on the criterion for the plug flow transition was observed. The experimental data points of plug flow in the 3-D micro-fin tubes were also obtained in the same regime of smooth tube in Mandhane flow regime map. The Soliman flow regime map indicates the criterion for plug flow transition to be Fr = 0.4.

A Study of Flows Over Microgrooves for Different Flow Pattern

2006 ◽  
Author(s):  
Q. Chen ◽  
R. S. Amano
Keyword(s):  
Flow Regime ◽  
Annular Flow ◽  
Plug Flow ◽  
Flow Patterns ◽  
Smooth Tube ◽  
Flow Transition ◽  
Number Range ◽  
Regime Map ◽  
Fin Tubes ◽  
Flow Regime Map

During condensation of R134a the flow patterns inside two three-dimensional (3-D) micro-fin tubes with different fin geometries were investigated. The flow patterns and their transitions were visibly observed and recorded. The experimental findings revealed the following results: a comparison of the condensation flow patterns in the 3-D micro-fin tubes with those in smooth tubes revealed no qualitative differences. The mist flow and the mist-annular flow that appeared in the smooth tube entrance region were not observed in 3-D micro-fin tubes. In the maps of the Mandhane flow regime and the Soliman flow regime, the area of annular flow region of the 3-D micro-fin tube extends towards lower Fr number range in the Soliman map and smaller vapor velocity range in the Mandhane map when compared with that of a smooth tube. The criterion of the flow regime transition between the annular flow and the wavy flow decreases from Fr = 7 to Fr = 2 in the Soliman flow regime map. However, no significant effect on the criterion for the plug flow transition was observed. The experimental data points of plug flow in the 3-D micro-fin tubes were also obtained in the same regime of smooth tube in Mandhane flow regime map. The Soliman flow regime map indicates the criterion for plug flow transition to be Fr = 0.4.

Experimental Study of Flow Regime Map in 5×5 Rod Bundle

2017 ◽  
Author(s):  
Hang Liu ◽  
Quanyao Ren ◽  
Liangming Pan ◽  
Takashi Hibiki ◽  
Wenxiong Zhou ◽  
...  
Keyword(s):  
Flow Regime ◽  
Gas Flow ◽  
Regime Transition ◽  
Rod Bundles ◽  
Flow Rates ◽  
Flow Regime Transition ◽  
Transition Criteria ◽  
Measured Flow ◽  
Regime Map ◽  
Flow Regime Map

In relation to development of the flow regime criteria for rod bundles, this paper provides an experimental flow regime map and compares the experimental map with the existing flow regime transition criteria for vertical rod bundles so far. An experiment of vertical adiabatic air-water flow was conducted under an atmosphere pressure conditions. The experiment facility was composed of 5×5 rod arranged on a square pitch in a square shell with 9.5 mm outside diameter and 12.6 mm pitch. A total of 242 data sets were acquired consisting of superficial gas flow rates, 0.02–8.69 m/s, and superficial liquid flow rates, 0.02–2.13 m/s. A new flow regime map was obtained and the flow regime transition model for rod bundles was validated by the measured flow regime map. A fairly good agreement with some discrepancies has been obtained between the existing flow regime transition criteria and measured flow regime maps for rod bundles.

Two-phase flow regime map predictions under microgravity

AIChE Journal ◽  
1988 ◽  
Vol 34 (1) ◽  
pp. 137-139 ◽  
Author(s):  
S. B. Reddy Karri ◽  
V. K. Mathur
Keyword(s):  
Flow Regime ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Regime Map ◽  
Flow Regime Map
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