Abstract Pool boiling heat transfer of saturated FC-72 under atmospheric pressure was studied for porous lattice structures fabricated using the Selective Laser Melting (SLM) technique. The substrates possess repeating geometry of octet-truss unit cell and were varied with unit cell sizes of 2.0 mm, 3.0 mm and 5.0 mm and structure heights of 2.5 mm, 5.0 mm and 10.0 mm. In comparison with a plain surface, the porous structures show significant enhancement in nucleate boiling heat transfer coefficients and delay of Critical Heat Flux (CHF). The enhancement is attributed to the increased surface area, increased nucleation site density and capillary-assisted suction of the porous structure. The porous structure allows sustained liquid replenishment which delayed the hydrodynamic choking and CHF significantly. The best performing substrate with the 3-mm unit cell size and 5-mm structure height has an average nucleate boiling heat transfer coefficient of 1.35 W/cm2·K, which is 2.81 times that of the plain surface at 0.48 W/cm2·K. Heat transfer mechanisms are proposed for the different heat flux levels of the porous structures based on visual observations. The boiling patterns are classified as low, mid, high and very-high heat flux levels. At high heat flux level, two separate modes of stable and unstable boiling patterns are observed. For the stable boiling pattern, there are distinct bubble departure and liquid replenishment pathways, thus allowing a good convection flow. However, for the unstable boiling pattern, there is major liquid–vapor counter-flow, which disrupts the orderly liquid replenishment pathway.

中文翻译：

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使用选择性激光熔化产生的多孔晶格结构增强饱和池沸腾

摘要 针对使用选择性激光熔化 (SLM) 技术制造的多孔晶格结构，研究了饱和 FC-72 在大气压下的池沸腾传热。基板具有八位组桁架单元格的重复几何形状，单元格尺寸为 2.0 毫米、3.0 毫米和 5.0 毫米，结构高度为 2.5 毫米、5.0 毫米和 10.0 毫米。与平坦表面相比，多孔结构在核沸腾传热系数和临界热通量 (CHF) 延迟方面表现出显着增强。增强归因于增加的表面积、增加的成核位点密度和多孔结构的毛细管辅助抽吸。多孔结构允许持续的液体补充，这显着延迟了流体动力阻塞和 CHF。具有 3 毫米晶胞尺寸和 5 毫米结构高度的最佳性能基板的平均核沸腾传热系数为 1.35 W/cm2·K，是 0.48 W/cm2·K 时平面的 2.81 倍. 基于目视观察，针对多孔结构的不同热通量水平提出了传热机制。沸腾模式分为低、中、高和非常高的热通量水平。在高热通量水平下，观察到稳定和不稳定沸腾模式的两种不同模式。对于稳定的沸腾模式，有明显的气泡离开和液体补充途径，从而允许良好的对流流动。然而，对于不稳定的沸腾模式，存在主要的液-气逆流，这破坏了有序的液体补充途径。