Interface Tracking Simulation for Subcooled Flow Boiling Using VOSET Method

This article presents a numerical simulation on subcooled flow boiling at a high-pressure condition. An interface tracking method, VOSET, was used to handle the moving interface, and conjugate heat transfer between the wall and the fluid was included in the numerical model. In order to consider the evaporation on the microlayer below a growing bubble, a depletable micorlayer model was employed. Our simulation illustrated typical processes of subcooled boiling flow including bubble sliding, coalescence, detachment and annihilation, and revealed many mechanisms in increasing the heat transfer coefficient. A transition in flow regime from isolated bubbly flow to elongated bubbly flow was reproduced by our simulations. The void fraction obtained by time-averaging the volume fraction of the vapor phase under various flow conditions was analyzed.

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Flow Pattern Analysis and Heat Transfer Characteristics During Subcooled Flow Boiling in a Rectangular Microchannel on ZnO Microrod Surface

Journal of Heat Transfer ◽

10.1115/1.4052434 ◽

2021 ◽

Vol 143 (12) ◽

Author(s):

Yuhao Lin ◽

Junye Li ◽

Jia Sun ◽

Wei Li ◽

Yanlong Cao

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Flow Pattern ◽

Titanium Surface ◽

Flow Boiling ◽

Bubbly Flow ◽

Heat Transfer Characteristics ◽

Rectangular Microchannel ◽

Subcooled Flow Boiling ◽

Subcooled Flow

Abstract The combination of microstructured surface and microchannel flow boiling is expected to solve the thermal management problems of high-heat-flux devices. In this study, the experimental investigation of subcooled flow boiling in a high aspect ratio, one-sided heating rectangular microchannel was conducted with de-ionized water as the working fluid. ZnO microrods were synthesized on the titanium surface to be used as the heated surface compared with the bare titanium surface. A facile image tool is utilized to process the flow patterns photographed by a high-speed camera, which is analyzed with the heat transfer characteristics. The flow pattern of isolated bubbly flow reveals the large number of nucleation sites formed on the microrod surface but the heat transfer performance deteriorates with increasing mass flux because of the smaller bubble area and weaker nucleation. With increasing heat flux, the flow pattern changes from isolated bubbly flow to alternating bubbly/slug flow and alternating slug/annular flow. The latter flow pattern is confirmed to bring a higher heat transfer coefficient due to the larger area of thin-film evaporation. Compared with the bare surface, a higher heat transfer coefficient is achieved on the ZnO microrod surface for up to 37% due to the more nucleate sites and strengthened convective evaporation. Therefore, this surface might be suitable for heat dissipation in the watercraft or aerospace industry considering the low density, strong intensity, and corrosion resistance of titanium.

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Experimental investigation and comparison of subcooled flow boiling of TiO2 nanofluid in a vertical and horizontal tube

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406212466765 ◽

2012 ◽

Vol 227 (8) ◽

pp. 1742-1753 ◽

Cited By ~ 21

Author(s):

E Abedini ◽

A Behzadmehr ◽

H Rajabnia ◽

SMH Sarvari ◽

SH Mansouri

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Transfer Coefficient ◽

Turbulent Flows ◽

Base Fluid ◽

Volume Fraction ◽

Flow Boiling ◽

Horizontal Tube ◽

Subcooled Flow Boiling ◽

Subcooled Flow

In this study, variations of local heat transfer coefficient are obtained in subcooled flow boiling conditions for water/TiO2 nanofluid in a vertical and horizontal tube. The results for the base fluid are compared with the predictions of the well known Shah correlation and Gnielinski formula for laminar and turbulent flows for single-phase forced convection and also with Chen correlation for subcooled flow boiling. A good agreement between the results is realized. At the subcooled regime, heat transfer coefficient of nanofluid is less than that of the base fluid and it decreases by increasing nanoparticle concentration for both of the channels; however, addition of the nanopraticles into the fluid causes that the vapor volume fraction increases.

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Experimental Study on Local Subcooled Flow Boiling Heat Transfer in a Vertical Mini-Gap Channel

ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2016-7959 ◽

2016 ◽

Author(s):

Jun-ye Li ◽

Zhao-zan Feng ◽

Carolyn Coyle ◽

Thomas J. McKrell ◽

Jacopo Buongiorno ◽

...

Keyword(s):

Heat Transfer ◽

Experimental Study ◽

Heat Transfer Coefficient ◽

Test Section ◽

Flow Boiling ◽

Bubbly Flow ◽

Local Heat Transfer ◽

Local Heat ◽

Subcooled Flow Boiling ◽

Subcooled Flow

An experimental study of subcooled flow boiling in a high-aspect-ratio, one-sided heating rectangular mini-gap channel was conducted using deionized water. The local heat transfer coefficient, onset of nucleate boiling, and flow pattern of subcooled boiling were investigated. The influence of heat flux and mass flux were studied with the aid of a high-speed camera. The results show that the flow pattern was mainly isolated bubbly flow when the narrow microchannel was placed vertically. The bubbles generated at lower mass fluxes were larger and did not easily depart, forming elongated bubbly flow and flowing upstream. The thin film evaporation mechanism dominated the entire test section due to the elongated bubbles and transient local dryout as well as rewet. The local heat transfer coefficient near the exit of the test section was larger.

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