交错排列柱状微结构表面池沸腾换热实验研究
Experimental Study on the Pool Boiling Heat Transfer on Staggered Micro？？Pin？？Finned Surfaces

为了进一步提高交错排列柱状微结构表面的换热性能,通过改变柱状微结构中心距和形状以提高表面换热系数及临界热流密度。以FC？？72为工质,对不同的交错排列柱状微结构硅片在3种过冷度(15、25、35 K)下进行了池沸腾换热实验研究,并与同工况下光滑表面硅片的结果进行了对比。通过干腐蚀技术在硅片表面加工出宽×高为30 μm×60 μm、30 μm×120 μm的方柱微结构,中心距分别为45、60、75 μm,以及直径为38 μm、中心距为60 μm、高度分别为60 μm和120 μm的圆柱微结构。实验结果表明,临界热流密度和沸腾换热系数并非随中心距的增大呈现出单调增或减的规律。中心距为45 μm的表面在核态沸腾区具有更高的换热系数,而对于高度为60、120 μm的方柱微结构,临界热流密度最高的分别是中心距为60 μm的表面(54？？6 W/cm2)和中心距为120 μm的表面(60？？72 W/cm2)。当方柱中心距与边长之比大于等于2时,增大中心距对临界热流密度影响很小,最大增加了2％;当方柱中心距与边长之比小于2时,增大中心距对临界热流密度有显著影响,最大增加了14％。当换热面积相同时,圆柱微结构的换热性能要好于方柱微结构,并且临界热流密度相比于方柱微结构表面和光滑表面分别最大提高了13％和124％。另外,临界热流密度随着过冷度的增大而增大,同时沸腾起始点有所滞后。
In order to enhance the heat transfer performance, an experimental study on the pool boiling heat transfer was conducted at three different degrees of subcooling (15, 25, 35 K) for different staggered micro？？pin？？finned surfaces of silicon chips in FC？？72, and smooth surface was also tested for comparison. The dimensions of the silicon chips were 10 mm×10 mm×0？？5 mm (length×width×thickness), and the micro？？pin？？finned silicon surfaces were fabricated by dry etching technique. Three center？？to？？center spacings (45, 60, 75 μm) were chosen for two kinds of square micro pin？？fins of 30 μm×60 μm and 30 μm×120 μm (width×height). One center？？to？？center spacing of 60 μm was chosen for two different circular micro pin？？fins of 38 μm×60 μm and 38 μm×120 μm (diameter×height). The center？？to？？center spacing of fins was found to have significant effects on the boiling heat transfer coefficient and critical heat flux, but the influence was not monotonous. In nuclear boiling, the surface with the center？？to？？center spacing of 45 μm showed the highest heat transfer coefficient than other surface with the same fin height. The surface with the center？？to？？center spacing of 60 μm showed the highest critical heat flux (54？？6 W/cm2) for the surfaces with a fin height of 60 μm, while the surface with the center？？to？？center spacing of 75 μm showed the highest critical heat flux (60？？72 W/cm2) for the surfaces with a fin height of 120 μm. When the ratio of center？？to？？center spacing to thickness was greater than or equal to 2, the center？？to？？center spacing had slight effect on critical heat flux, and the difference was 2％ at most. However, when the ratio was less than 2, the difference reached up to 14％. Compared with square pin？？fins, circular pin？？fins showed better heat transfer performance under the same surface area, and the critical heat flux was increased by 13％ and 124％ for square micro？？pin？？finned surface and smooth surface respectively. Besides, the critical heat flux was