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首页> 外文期刊>International Journal of Heat and Mass Transfer >Internal convective jumping-droplet condensation in tubes
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Internal convective jumping-droplet condensation in tubes

机译：管内对流跳跃液滴凝结

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摘要

Water vapor condensation governs the efficiency of a number of industrial processes. Jumping-droplet condensation of water has recently been shown to have a 10× heat transfer enhancement compared to filmwise condensation due to the removal of condensate at much smaller length scales (∼1 µm diameter). However, the removal efficiency of jumping droplets can be limited by return to the surface due to gravity, entrainment in bulk convective vapor flow, and entrainment in local condensing vapor flow. If used appropriately, convective condensation has the potential to entrain droplets and impede their return to the surface. In this work, a comprehensive model of internal convective jumping-droplet condensation in a superhydrophobic tube has been developed for constant heat flux boundary conditions. Laminar boundary layer theory was used to model the vapor flow inside the tube with condensation modeled as vapor suction. We analyzed the effects of jumping droplet size (1 < R_d<100 µm), condensation heat flux (0 < q < 10 W/cm~2), initial jumping location axially along the tube (0 < x < 5 m) and radial position (0 < theta < 2π), entering vapor mass flux (0.05 < G < 1.5 kg/m~2 s), and pipe radius (1 mm < a < 30 cm), on droplet trajectory, overall heat transfer performance, and pressure drop. By linking droplet return with droplet jumping (multi-hop), we develop a framework to predict macroscopic droplet motion along the tube, and offer guidelines for the minimization of drag force and maximization of overall condensation heat transfer. The reduced theoretical pressure drop and enhanced heat transfer performance of convective internal jumping-droplet condensation shows potential of applicability in air-cooled condensers, and presents a framework for novel flow humidification and dehumidification technologies with appropriate design and flow separation.
机译：水蒸气冷凝控制许多工业过程的效率。与薄膜状冷凝相比，水的跳跃式液滴冷凝近来已显示出10倍的传热增强效果，这是因为以较小的长度比例（直径约1 µm）去除了冷凝物。但是，由于重力，夹带大对流蒸气流和夹带局部冷凝蒸气流而返回表面，会限制跳跃液滴的去除效率。如果使用得当，对流凝结可能会带走液滴并阻止液滴返回表面。在这项工作中，对于恒定的热通量边界条件，已经开发了超疏水管中内部对流跳跃液滴凝结的综合模型。层流边界层理论用于模拟管内的蒸汽流动，冷凝模型为蒸汽吸力。我们分析了跳跃液滴尺寸（1

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