A Two-Phase Flow Regime Map for a Maple-Type Nuclear Research Reactor Fuel Channel: Effect of Hexagonal Finned Bundle

1997 ◽  
Vol 118 (2) ◽  
pp. 151-161 ◽  
Author(s):  
Glenn D. Harvel ◽  
J. S. Chang ◽  
V. Santhana Krishnan
Keyword(s):  
Flow Regime ◽  
Research Reactor ◽  
Nuclear Research ◽  
Phase Flow ◽  
Two Phase ◽  
Fuel Channel ◽  
Channel Effect ◽  
Nuclear Research Reactor ◽  
Regime Map ◽  
Flow Regime Map

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

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

Study of Interfacial Structures: Bubbly Flow in 1.27 cm Diameter Pipe

2002 ◽  
Author(s):  
S. Paranjape ◽  
S. Kim ◽  
M. Ishii ◽  
J. Uhle
Keyword(s):  
Flow Regime ◽  
Two Phase Flow ◽  
Bubbly Flow ◽  
Bubble Velocity ◽  
Phase Flow ◽  
Two Phase ◽  
Interfacial Structures ◽  
Radial Profiles ◽  
Regime Map ◽  
Flow Regime Map

The objective of the present research is to study the flow regime map, the detailed interfacial structures, and the bubble transport in an adiabatic air-water two-phase flow mixture, flowing upward through a vertical round pipe having 1.27 cm. inner diameter. The flow regime map is obtained by processing the characteristic signals acquired from an impedance void meter, using a self-organized neural network. The local two-phase flow parameters are measured by the state-of-the-art four-sensor conductivity probe at three axial locations in the pipe. The measured local parameters include void fraction (α), interfacial area concentration (ai), bubble frequency (fb), bubble velocity (Ub) and bubble Sauter mean diameter (Dsm). The radial profiles of these parameters and their development along the axial direction reveals the structure of the two phase mixture and the bubble interaction mechanisms.

scholarly journals Some problems of hydrodynamics of two-phase flow mixtures in minichannels

2014 ◽  
Vol 35 (2) ◽  
pp. 93-101
Author(s):  
Monika Wengel ◽  
Barbara Miłaszewicz ◽  
Roman Ulbrich
Keyword(s):  
Two Phase Flow ◽  
Early Stage ◽  
Phase Flow ◽  
Test Results ◽  
Two Phase ◽  
Key Issues ◽  
Gas Liquid Flow ◽  
Regime Map ◽  
Flow Regime Map

Abstract Gas-liquid two-phase flow in minichannels has been the subject of increased research interest in the past few years. Evaluation, however, of today’s state of the art regarding hydrodynamics of flow in minichannels shows significant differences between existing test results. In the literature there is no clear information regarding: defining the boundary between minichannels and conventional channels, labelling of flow patterns. The review of literature on the hydrodynamics of gas-liquid flow in minichannels shows that, despite the fact that many research works have been published, the problem of determining the effect of diameter of the minichannel on the hydrodynamics of the flow is still at an early stage. Therefore, the paperpresents the results of research concerning determination of flow regime map for the vertical upward flow in minichannels. The research is based on a comprehensive analysis of the literature data and on the research that has been carried out. Such approach to the mentioned above problems concerning key issues of the two-phase flow in minichannels allowed to determine ranges of occurrence of flow structures with a relatively high accuracy.

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.

An Updated Two-Phase Flow Regime Map in Active PEM Fuel Cells Based on a Force Balance Approach

2015 ◽  
Author(s):  
Lifeng Zhang ◽  
Ryan Anderson
Keyword(s):  
Fuel Cells ◽  
Pressure Drop ◽  
Flow Regime ◽  
Current Density ◽  
Water Droplet ◽  
Pem Fuel Cells ◽  
Force Balance ◽  
Two Phase ◽  
Regime Map ◽  
Flow Regime Map

The water balance in proton exchange membrane (PEM) fuel cells still remains a topic of much investigation in order to maintain satisfactory cell performance. One specific water management issue relates to the gas-liquid flows that occur when water enters the reactant flow field channels, which are typically microchannels or minichannels. Due to its unique water introduction, the Lockhart-Martinelli (LM) approach has been revised for its applicability in predicting the two-phase pressure drop in these channels where water emerges from a gas diffusion layer perpendicular to the direction of gas flow. In the revised LM approach, the Chisholm parameter C is found not to vary strongly as a function of key fuel cell operating variables (relative humidity, temperature, materials, gas stoichiometry), whereas it does vary as a function of flow regime and current density. A new flow regime map was proposed based on all pressure drop data collected from active fuel cells, where an accumulating flow regime is presented in addition to single-phase, film/droplet, and slug flow. The proposed accumulating regime is linked to water droplet dynamics, namely, water droplet emergence, growth, and detachment. A force balance approach shows when detachment will occur, which clarifies the bounds of the accumulating regime in terms of superficial gas velocity (gas stoichiometry ratio) and liquid velocity (current density). The balance considers different wetting scenarios in the channels and a range of superficial velocities of importance to PEM fuel cells.

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