Abstract

Numerical modeling based on volume of fluid (VOF) method is conducted and experimentally validated for the two-phase flow and heat transfer in a loop thermosyphon for wide filling ratios. The results show that, under the 87% filling ratio, the loop is dominated by bubbly flow and sub-cooled flow boiling, with sensible heat transfer enhanced by bubble pumping effect, which is beneficial for wobbling, tilting, and mobile applications to avoid evaporator dry-out. Under the 64% filling ratio, geyser boiling instability occurs. A train of bubble-liquid intermittently passes the loop summit under the collaboration of buoyancy, gravity, viscous, and surface tension forces, causing intense flow and temperature oscillations, enhancing both latent and sensible heat transfer. Under the 38% filling ratio, the characteristic flow patterns are churn flow, mist flow, and film condensing, leading to highly efficient latent heat transfer.

摘要

进行了基于流体体积（VOF）方法的数值建模，并针对宽填充比的环路热虹吸管中的两相流动和传热进行了实验验证。结果表明，在87％的填充率下，环路以气泡流和过冷流沸腾为主导，并通过气泡泵送作用增强了显热传递，有利于摆动，倾斜和移动应用以避免蒸发器变干。在64％的填充率下，发生间歇沸腾不稳定性。在浮力，重力，粘性和表面张力的共同作用下，一连串的气泡-液体间歇地通过回路顶峰，从而引起强烈的流动和温度波动，从而增强了潜热和显热的传递。在38％的填充率下，特征流型为搅动流，