Effects of the gap size on the flow pattern maps in a mini-gap annular channel

Pipathattakul, Manop; Mahian, Omid; Dalkılıç, Ahmet Selim

doi:10.1016/j.expthermflusci.2014.06.006

Cited by 9 publications

(6 citation statements)

References 13 publications

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“…This paper is a continuation of the authors previous work, some relevant examples of the investigation of flow visualization in rectangular and annular channels are shown in Ref. [12][13][14][15]. They conducted experiments to visualize the flow patterns of single-and two-phase flows in small gap channels.…”

Section: Experimental Apparatus and Proceduresmentioning

confidence: 93%

Experimental and numerical investigations of heat transfer and flow characteristics of cross-cut heat sinks

Chingulpitak

Chimres

Nilpueng

2016

International Journal of Heat and Mass Transfer

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Section: Experimental Apparatus and Proceduresmentioning

confidence: 93%

Experimental and numerical investigations of heat transfer and flow characteristics of cross-cut heat sinks

Chingulpitak

Chimres

Nilpueng

2016

International Journal of Heat and Mass Transfer

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“…Bubble generation requires a mass of latent heat and transports energy from a hot region to a cold liquid in subcooled flow boiling [8]. Subcooled flow boiling is applied to many fields, such as pulsating heat pipes, refrigeration, nuclear, electronic cooling, biological engineering, and aerospace [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Subcooled Flow Boiling in a Threaded Tube and Investigation of Heat Transfer and Bubble Behavior

Lei,

Wang,

Xie

et al. 2023

Energies

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Three-dimensional subcooled flow boiling of R134a in a threaded tube was numerically simulated at the conditions of 200~400 kW/m2 heat flux, 3~20 K inlet subcooling, and 0.2~0.6 m/s inlet velocity. The bubble behavior in the horizontal threaded tube with 0.581 mm thread tooth height was observed. The effect of heat flux, inlet subcooling, and inlet velocity on bubble departure diameter and heat transfer coefficient were explored. The results presented the whole growth process of five kinds of bubbles. It was found that the bubbles either collapsed in cold liquid after leaving the heating wall or grew along the axial direction and contacted the heating wall. And there was no bubble sliding during the growth. In addition, the most important and special characteristic of bubble behavior in threaded tubes was the phenomenon of the bubble passing through the cavity. The coalescence and breakup behavior occurred after the bubble passed through the cavity. According to the discussions of the departure diameter and heat transfer coefficient, it was inferred that the bubble departure diameter increased with the increase of heat flux from 200~400 kW/m2 and subcooling from 3~20 K while decreasing with the increase of inlet velocity from 0.2~0.6 m/s. And due to the influence of the threaded tube structure, there are special points in the change of bubble departure diameter. The heat transfer coefficient of the bubbles in the threaded tube was higher than the smooth tube, which was increased by 1.5~12.5%. The heat transfer coefficient increased with the increase of heat flux and subcooling and is closely related to the bubble departure diameter.

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“…Subcooled boiling as an efficient heat transfer method has been applied in many fields; for example, commercial refrigeration, the electronics industry, nuclear power and the aerospace industry [1][2][3][4][5]. During subcooled flow boiling, the bubble with non-zero velocity typically slides along the heating wall until departure and annihilation.…”

Section: Introductionmentioning

confidence: 99%

“…As reviewed above, the bubble sliding characteristics and dynamics of R134a during subcooled flow boiling flow are not reported and clearly understood; thus, the bubble sliding characteristics and bubble sliding dynamics of R134a have been investigated to better understand the bubble sliding for heat transfer enhancement in this paper. In addition, the gap structure is used as a fluid channel because of the sufficient heat transfer in small spaces and its application in refrigeration systems and nuclear fields [3,23]. The study's purpose is to investigate the bubble velocity, bubble departure diameter, sliding distance and bubble sliding dynamics under the conditions of 0.2 to 0.8 m/s inlet velocities.…”

Section: Introductionmentioning

confidence: 99%

Bubble Sliding Characteristics and Dynamics of R134a during Subcooled Boiling Flow in a Narrow Gap

Wang

Xie

et al. 2023

Mathematics

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The numerical method was used to study bubble sliding characteristics and dynamics of R134a during subcooled flow boiling in a narrow gap. In the numerical method, the volume of fraction (VOF) model, level set method, Lee phase change model and the SST k − ω turbulent model were adopted for the construction of the subcooled flow boiling model. In order to explore bubble sliding dynamics during subcooled flow boiling, the bubble sliding model was introduced. The bubble velocity, bubble departure diameter, sliding distance and bubble sliding dynamics were investigated at 0.2 to 5 m/s inlet velocities. The simulation results showed that the bubble velocity at the flow direction was the most important contribution to bubble velocity. Additionally, the bubble velocity of 12 bubbles mostly oscillated with time during the sliding process at 0.2 to 0.6 m/s inlet velocities, while the bubble velocity increased during the sliding process due to the bubble having had a certain inertia at 2 to 5 m/s inlet velocities. It was also found that the average bubble velocity in flow direction accounted for about 80% of the mainstream velocities at 0.2 to 5 m/s. In the investigation of bubble sliding distance and departure diameter, it was concluded that the ratio of the maximum sliding distance to the minimum sliding distance was close to two at inlet velocities of 0.3 to 5 m/s. Moreover, with increasing inlet velocity, the average sliding distance increased significantly. The average bubble departure diameter obviously increased from 0.2 to 0.5 m/s inlet velocity and greatly reduced after 0.6 m/s. Finally, the investigations of the bubble sliding dynamics showed that the surface tension dominated the bubble sliding process at 0.2 to 0.6 m/s inlet velocities. However, the drag force dominated the bubble sliding process at 2 to 5 m/s inlet velocities.

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Effects of the gap size on the flow pattern maps in a mini-gap annular channel

Cited by 9 publications

References 13 publications

Experimental and numerical investigations of heat transfer and flow characteristics of cross-cut heat sinks

Experimental and numerical investigations of heat transfer and flow characteristics of cross-cut heat sinks

Numerical Simulation of Subcooled Flow Boiling in a Threaded Tube and Investigation of Heat Transfer and Bubble Behavior

Bubble Sliding Characteristics and Dynamics of R134a during Subcooled Boiling Flow in a Narrow Gap

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