Two-Phase Flow Patterns and Flow-Pattern Maps: Fundamentals and Applications

Comparison of various definitions of threshold diameters for microscale channels: (a) water and (b) CO2 by Cheng and Mewes (42)

(a) Schematic of flow patterns in vertical upward gas-liquid cocurrent flow; (b) schematic of flow patterns in horizontal gas-liquid cocurrent flow (1)

Schematic of flow patterns and the corresponding heat transfer mechanisms for upward flow boiling in a vertical tube (1-2)

Schematic of flow patterns and the corresponding heat transfer mechanisms and qualitative variation of the heat transfer coefficients for flow boiling in a horizontal tube (1-2)

Schematic of flow patterns for horizontal gas-liquid cocurrent flow in condensation (49)

The Baker (6) flow-pattern map for horizontal gas-liquid cocurrent flow

The Hewitt and Roberts (5) flow-pattern map for vertical upward gas-liquid cocurrent flow

The Taitel and Dukler (7) flow-pattern map for horizontal gas-liquid cocurrent flow: coordinates of curves A and B are Fr versus X, coordinates of curve C are K versus X, and coordinates of curve D are T versus X

The Kattan–Thome–Favrat flow-pattern map (solid lines) (10-12) compared to the Steiner map (9) (dashed lines) evaluated for R410A at Tsat=5°C in a 13.84mm internal diameter tube at different heat fluxes (36). (A stands for annular flow, I stands for intermittent flow, M stands for mist flow, S stands for stratified flow, and SW stands for stratified-wavy flow. The stratified to stratified-wavy flow transition is designated as S-SW, the stratified-wavy to intermittent/annular flow transition is designated as SW-I∕A, the intermittent to annular flow transition is designated as I-A, and so on.)

The flow-pattern map of Wojtan (18-19) for R22 at Tsat=5°C in a 13.84mm internal diameter tube at G=100kg∕m2s and q=2.1kW∕m2 and the corresponding prediction of heat transfer coefficients (dashed line) based on the map (D stands for the dryout region, slug stands for slug flow, and others have the same meanings as in Fig. 9)

The CO2 flow-pattern map of Cheng (22-23) evaluated for the test condition of Yun (52): Deq=2mm, G=1500kg∕m2s, Tsat=5°C, and q=30kW∕m2 and the corresponding prediction of heat transfer coefficients (dashed line) (B stands for bubbly flow and others have the same meanings as in Figs.  9, 10)

The probabilistic flow map with time fraction curve fits for R134a at 10°C and a mass flux of 50kg∕m2s in a six-port microchannel (data obtained from Niño (53)) by Jassim and Newell (54)

Photographs of flow patterns in a 1.1mm diameter test section of Triplett (47)

Comparison between the experimental flow patterns observed by Triplett (47) for a 1.1mm diameter circular test section to the experimental flow-regime transition lines of Damianides and Westwater (101) based on a 1mm diameter circular test section

Comparison of the predicted flow-regime boundaries of the Ullmann and Brauner (122-123) flow map in a horizontal 1mm tube to the experimental data of Triplett (47), where εG is the cross-sectional void fraction and EoD is the Eotvös number

Wedge flow regime: (a) drying bubble, (b) consecutive images of a hybrid bubble, and (c) lubricated bubble, observed by Cubaud and Ho (94)

Flow patterns in a 0.509mm microchannel for R245fa at 35°C and 500kg∕m2s, observed by Revellin and Thome (90-92) at the exit of a microevaporator channel

Flow-pattern observations With experimental transition lines for R134a, D=0.5mm, L=70.7mm, Tsat=35°C and ΔTsub=5°C using laser plotted in two different formats: (a) flow-pattern observations with transition lines and (b) flow-pattern map by Revellin and Thome (91-92).

Proposed flow-pattern categories in two-phase flow across a tube bundle: (a) bubbly, (b) intermittent, (c) annular, (d) stratified, (e) stratified-spray from Grant and Chisholm (135), and (f) intermittent downward flows, (g) falling film and (h) churn from Xu (134) shown by Ribatski and Thome in Refs. 125-126.

The Coleman and Garimella (144) flow-regime map for R134a condensation in a 4.91mm circular tube

Video images of condensing R-134a at 300kg∕m2s, 500kg∕m2s, and 800kg∕m2s in a smooth tube by Liebenberg and Meyer (136) superimposed on the map of El Hajal (16)

Schematic flow patterns of highly viscous Newtonian fluid two-phase flow in vertical channels: B—bubble flow, S—slug flow, F—froth flow, and A—annular flow observed by Dziubinski (175)

Schematic of the three-zone evaporation model for elongated bubble flow regime by Thome (212)

Comparison of the predicted frictional pressure gradients by the Moreno-Quibén and Thome model to the experimental frictional pressure gradients for R410A at D=8mm, Tsat=5°C, G=350kg∕m2s and q=6–9kW∕m2, where 94.12% of the data were predicted within ±30%(34-36)

Comparison of predicted frictional pressure gradient by the CO2 pressure drop model of Cheng (22) to the experimental data of Bredesen (218) at the experimental conditions: G=400kg∕m2s, Tsat=−10°C, D=7mm, and q=9kW∕m2

Comparison of the predicted pressure drop gradients by the probabilistic model and the measured values for R134a at 10°C in six-port microchannels by Jassim and Newell (54)