Two-phase R1234yf flow inside horizontal smooth circular tubes: Heat transfer, pressure drop, and flow pattern

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.

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Boiling heat transfer, pressure drop, and flow pattern in a horizontal square minichannel

International Journal of Heat and Fluid Flow ◽

10.1016/j.ijheatfluidflow.2019.108433 ◽

2019 ◽

Vol 78 ◽

pp. 108433 ◽

Cited By ~ 2

Author(s):

Daisuke Jige ◽

Norihiro Inoue

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Flow Pattern ◽

Boiling Heat Transfer ◽

Transfer Pressure

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

Journal of Electronic Packaging ◽

10.1115/1.1756589 ◽

2004 ◽

Vol 126 (3) ◽

pp. 288-300 ◽

Cited By ~ 16

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.

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CO2 and R410A flow boiling heat transfer, pressure drop, and flow pattern at low temperatures in a horizontal smooth tube

International Journal of Refrigeration ◽

10.1016/j.ijrefrig.2006.08.007 ◽

2007 ◽

Vol 30 (1) ◽

pp. 166-178 ◽

Cited By ~ 68

Author(s):

C.Y. Park ◽

P.S. Hrnjak

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Flow Pattern ◽

Low Temperatures ◽

Boiling Heat Transfer ◽

Flow Boiling ◽

Smooth Tube ◽

Flow Boiling Heat Transfer ◽

Transfer Pressure

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Numerical Studies on Non-Boiling Two-Phase Flows in Microtubes and Microchannels: A Review

ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels: Parts A and B ◽

10.1115/fedsm-icnmm2010-30276 ◽

2010 ◽

Cited By ~ 1

Author(s):

V. Talimi ◽

Y. S. Muzychka

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Flow Pattern ◽

Research Literature ◽

Heat Transfer Characteristics ◽

Liquid Slug ◽

Two Phase Flows ◽

Two Phase ◽

Numerical Studies ◽

Slug Flows

Numerical studies on the hydrodynamic and heat transfer characteristics of two-phase flows in small tubes and channels are reviewed. These flows are gas-liquid and liquid-liquid slug flows. The review is categorized into two groups of studies: circular and non-circular channels. Different aspects such as slug formation, slug shape, flow pattern, pressure drop and heat transfer are of interest. According to this review, there are some large gaps in the research literature, including pressure drop and heat transfer in liquid-liquid slug flows. Gaps in research are also found in applications of non-circular ducts, pressure drop and heat transfer in meandering microtubes and microchannels for both of gas-liquid and liquid-liquid two-phase flows.

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