<p>Flow boiling in the microchannel is a promising way of high heat flux removal. Although slug and annular flows are the most commonly-seen flow patterns, few numerical studies were conducted towards the annular flow due to its complex nature. Utilizing the VOF method and phase change model, the three-dimensional numerical investigation of annular flow boiling is carried out with water as the working fluid. The tested cross-section aspect ratio (AR) is 0.125, 0.25, 0.5, 1, 2, 4, and 8. The channel is heated from the bottom and side walls while the top wall is adiabatic. The dominated heat transfer mechanism during annular flow in microchannel is convective evaporation and thinner liquid film contributed to better heat transfer performance. For AR ≥ 1, the Nusselt number firstly increased then went down, with the peak value at AR = 2, which attributes to the thinnest liquid film and less liquid accumulated at the corners. Compared the cases of AR＞1 and AR＜1, because the microchannel with AR＜1 had two longer walls, the evaporation rate was tremendously higher. Consequently, the channel with an aspect ratio of 0.5 showed the best heat transfer performance in the current study.</p><p>KEYWORDS: Numerical simulation, Microchannel flow boiling, Annular flow, Aspect ratio</p>

Numerical Simulation of Annular Flow Boiling in Microchannel

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

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