Enhanced heat transfer of flow boiling combined with jet impingement

作者: Jinjia Wei*, Yonghai Zhang,Jianfu Zhao, Dong Guo
发表/完成日期: 2013-01-01
期刊名称: Interfacial Phenomena and Heat Transfer. 2013. 1(1): 13-28.
期卷: 1(1)
The experiment was made at flow boiling heat transfer of FC-72 on micro-pin-finned chips with jet impingement. The experimental conditions cover two different liquid subcooling degrees (25, 35 K), three different crossflow velocities (Vc = 0.5, 1, 1.5 m/s), and three different jet velocities (Vj = 0, 1, 2 m/s) in the direction perpendicular to chip surface. The dimension of the silicon chips is 10 mm × 10 mm × 0.5 mm (length × width × thickness) on which four kinds of micro-pin-fins with the dimensions of 30 × 30 × 60 µm3, 50 × 50 × 60 µm3, 30 × 30 × 120 µm3, 50 × 50 × 120 µm3 (width × thickness × height, named PF30-60, PF50-60, PF30-120, PF50-120) were fabricated using the dry etching technique. A smooth surface (named chip S) was also tested for comparison. The results have shown that flow boiling combined with jet impingement gives a large heat transfer enhancement compared with pool boiling and flow boiling. It has been also found that micro-pin-finned surfaces enhance heat transfer compared with the smooth surface. For all chips, the maximum qCHF increases in the order of chips S, PF50-60, PF30-60, PF50-120, PF30-120, and qCHF increases with crossflow or jet velocities. The maximum allowable heat flux qmax is given by the qCHF if Tw,CHF < 85◦C and by q at Tw = 85◦C, if Tw,CHF > 85◦C. Effects of liquid subcooling, surface structure, and boiling heat transfer mode on maximum allowable heat flux were also investigated in the present experiment, and the combination of these influence factors of maximum allowable heat flux exerts a synergistic effect. The maximum allowable heat flux of chip S is 15.1 W/cm2 at ∆Tsub = 25 K by pool boiling, and the maximum allowable heat flux of micro-pin-fins by crossflow–jet combined boiling in the experiment is 167 W/cm2, which is 11.06 times as large as that for the smooth surface without additional flow
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