Heat Transfer and pressure drop characteristics of two-phase flow in helical coils

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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Single- and Two-Phase Flow Pressure Drop and Heat Transfer in Tubes

10.1007/978-3-030-87281-6 ◽

2022 ◽

Author(s):

Afshin J. Ghajar

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Two Phase Flow ◽

Phase Flow ◽

Two Phase ◽

Flow Pressure

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A Multiobjective Parameter Study of Two-Phase Flow Channel Design

ASME 2020 Heat Transfer Summer Conference ◽

10.1115/ht2020-9041 ◽

2020 ◽

Author(s):

Nicholas A. Evich ◽

Nicholas R. Larimer ◽

Mary I. Frecker ◽

Matthew J. Rau

Keyword(s):

Heat Transfer ◽

Pressure Drop ◽

Two Phase Flow ◽

Circular Cross Section ◽

Parameter Study ◽

Phase Flow ◽

Two Phase ◽

Flow And Heat Transfer ◽

High Heat Transfer ◽

Manufacturing Techniques

Abstract Advanced manufacturing techniques have improved dramatically in recent years and design freedom for engineered components and systems has never been greater. Despite these advancements, the majority of our design tools for thermal-fluids systems are still rooted within traditional architectures and manufacturing techniques. In particular, the complex nature of two-phase flow and heat transfer has made the development of design methods that can accommodate these complex geometries enabled by new manufacturing techniques challenging. Here, we investigate a new design method for two-phase flow systems. We conduct a multiobjective parameter study considering two-phase flow and heat transfer through a single channel with a circular cross section. To increase our design degrees of freedom, we allow the channel to increase or decrease in cross-sectional area along its flow length, but constrain the channel inlet and outlet to a constant hydraulic diameter. Maximizing heat transfer and minimizing pressure drop are the two design objectives, which we evaluate using two-phase heat transfer correlations and the Homogeneous Equilibrium Model. We find that using small expansion angles can greatly reduce two-phase flow pressure drop and also provide high heat transfer coefficients when compared to straight channel designs. We present a set of feasible designs for varying input heat fluxes, liquid mass flow rates, and channel orientation angles and show how the ideal expansion channel angle varies with these operational conditions.

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Numerical investigation on heat transfer and pressure drop characteristics of coupling transcritical flow and two-phase flow in a printed circuit heat exchanger

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2020.119557 ◽

2020 ◽

Vol 153 ◽

pp. 119557 ◽

Cited By ~ 2

Author(s):

Zhao-Rui Peng ◽

Qiu-Yun Zheng ◽

Jie Chen ◽

Si-Cong Yu ◽

Xin-Rong Zhang

Keyword(s):

Heat Transfer ◽

Heat Exchanger ◽

Pressure Drop ◽

Numerical Investigation ◽

Two Phase Flow ◽

Phase Flow ◽

Two Phase ◽

Printed Circuit ◽

Transcritical Flow

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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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