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本文利用小尺度光滑芯片(10 mm×10 mm×0.5 mm),通过控制加热电流方法,在北京落塔进行了持续3.6 s有效微重力时间的过冷池沸腾实验研究。在低热流和中等热流区,微重力条件下可以观察到稳态或准稳态池沸腾现象,传热特性基本维持不变;在中等热流区域,气泡的横向合并会引起合并后的大气泡表面剧烈震荡,进而引发合并大气泡从加热表面脱落。在高热流密度区,微重力条件下加热表面很快形成半球形状并几乎完全覆盖其表面的聚合大气泡;随后,由于高过冷液体冷凝作用,聚合大气泡收缩为半椭球形状,界面也变得更为光滑,且完全覆盖了加热表面,壁温曲线明显升高,可能提前发生临界热流或转变为膜态沸腾,导致微重力条件下沸腾换热显著恶化。
In this paper, a small-scale smooth chip (10 mm × 10 mm × 0.5 mm) was used to conduct a subcooled-pool boiling experiment with an effective micro-gravimetric time of 3.6 s at the falling tower in Beijing by controlling the heating current method. The steady-state or quasi-steady-state pool boiling phenomenon can be observed under the conditions of microtherm and low heat and moderate heat flow, and the heat transfer characteristics remain unchanged. In the middle heat flow area, the horizontal mergence of bubbles will cause the surface of the combined large bubble Severe shocks, which in turn lead to the merger of large bubbles from the heating surface. Under the conditions of high heat flux density and microgravity, the surface of the polymer is heated to a hemispherical shape and almost completely covers the surface of the polymer. Then, due to the condensation of the supercooled liquid, the polymer bubble shrinks to a semi-ellipsoidal shape, Becomes smoother and completely covers the heating surface. The curve of the wall temperature is obviously increased, and the critical heat flow may be preformed or transformed into membrane boiling, resulting in a significant deterioration of boiling heat transfer under microgravity.