Enhanced boiling structures based on the concept of separate liquid-vapor (L-V) pathways rely on the motion of the bubbles departing from the nucleating regions (NRs) to induce a macroconvective liquid jet impingement flow over adjacent non-boiling regions. Heat transfer in the non-boiling regions can be improved by incorporating microchannels which act as feeder channels (FCs) that also improve liquid directionality towards the NR. We hypothesize that the single-phase flow characteristics in the developing region of the FC contribute to the boiling enhancement and explore the interplay between the FC length, developing flow length, and departure bubble diameter. FC lengths shorter than the developing flow length benefit from the enhancement due to developing boundary layers over their entire length. However, FC lengths shorter than the departure bubble diameter suffer from bubble interference while FC lengths that are considerably longer than the developing flow length exhibit lower heat transfer rates in the fully developed region. This hypothesis was verified by conducting pool boiling experiments with four feeder channel lengths between 1 mm and 3 mm using HFE-7000, PP1, PP1C, and water. Three distinct regions: (i) interfering bubble, (ii) efficient L-V pathways, and (iii) diminished jet were identified to explain the boiling performance enhancement. This analysis will be beneficial in the pursuit to enhance critical heat flux (CHF) and heat transfer coefficient (HTC) on surfaces utilizing macroconvection mechanisms during boiling with different liquids.Enhanced boiling structures based on the concept of separate liquid-vapor (L-V) pathways rely on the motion of the bubbles departing from the nucleating regions (NRs) to induce a macroconvective liquid jet impingement flow over adjacent non-boiling regions. Heat transfer in the non-boiling regions can be improved by incorporating microchannels which act as feeder channels (FCs) that also improve liquid directionality towards the NR. We hypothesize that the single-phase flow characteristics in the developing region of the FC contribute to the boiling enhancement and explore the interplay between the FC length, developing flow length, and departure bubble diameter. FC lengths shorter than the developing flow length benefit from the enhancement due to developing boundary layers over their entire length. However, FC lengths shorter than the departure bubble diameter suffer from bubble interference while FC lengths that are considerably longer than the developing flow length exhibit lower heat transfer rates i...

中文翻译：

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宏观对流增强池沸腾过程中发展流长度与气泡离开直径之间的相互作用

基于分离的液-气 (LV) 路径概念的增强沸腾结构依赖于气泡从成核区域 (NR) 离开的运动，以在相邻的非沸腾区域上产生宏观对流液体射流冲击流。非沸腾区域的传热可以通过加入微通道来改善，这些微通道充当进料通道 (FC)，也可以改善液体向 NR 的方向性。我们假设 FC 发展区域的单相流动特性有助于沸腾增强，并探索 FC 长度、发展流动长度和离开气泡直径之间的相互作用。由于在其整个长度上发展边界层，FC 长度短于发展流动长度受益于增强。然而，短于离开气泡直径的 FC 长度会受到气泡干扰，而远大于发展流动长度的 FC 长度在完全发展的区域表现出较低的传热率。该假设通过使用 HFE-7000、PP1、PP1C 和水对四个长度介于 1 毫米和 3 毫米之间的进料器通道进行池沸腾实验得到验证。确定了三个不同的区域：(i) 干扰气泡、(ii) 有效的 LV 通路和 (iii) 射流减少，以解释沸腾性能的增强。该分析将有助于在不同液体沸腾期间利用宏观对流机制提高表面的临界热通量 (CHF) 和传热系数 (HTC)。基于分离的液-气 (LV) 路径概念的增强沸腾结构依赖于气泡从成核区 (NR) 出发的运动，以在相邻的非沸腾区上产生宏观对流液体射流冲击流。非沸腾区域的传热可以通过加入微通道来改善，这些微通道充当进料通道 (FC)，也可以改善液体向 NR 的方向性。我们假设 FC 发展区域的单相流动特性有助于沸腾增强，并探索 FC 长度、发展流动长度和离开气泡直径之间的相互作用。由于在其整个长度上发展边界层，FC 长度短于发展流动长度受益于增强。然而，