| 论文简介 |
An experimental study of pool boiling heat transfer was conducted for two types of micro-pin-finned surfaces (The staggered micro-pin-fins with the dimensions of 30 × 30 × 60 μm3 (width × thickness × height, named PF30-60-60) and the cylindrical micro-pin-fins with the dimensions of 38 × 60 × 60 μm3 (diameter × pitch × height, named PF38-60-60)), nanowire surface and TiO2 porous surface. The experimental conditions covered three different liquid subcoolings (15K, 25K, 35K), and dielectric liquid FC-72 was used as working fluid. Micro-pin-finned surfaces have strong liquid supply capacity and small flow resistance. Therefore, micro-pin-finned surfaces were ovserved much higher critical heat flux (CHF) than that of the smooth surface (Chip S). But for the nanowire surface and the TiO2 porous surface, their very small micro/nanostructures increased the liquid flow resistance and obstructed the liquid supplement. Therefore, their CHF enhancement is not obvious compared to that of Chip S. PF38-60-60 showed the best heat transfer performance, with over 120% increase of CHF compared to Chip S and the lowest superheat in the nucleate boiling heat transfer region. The micro/nanocavities diameter of nanowire surface is consistent with the effective nucleation sites diameter. Therefore it was found an obvious increase in heat transfer coefficient. In contrast, TiO2 porous surface can not improve the heat transfer coefficient significantly because the nanocavities diameter is too small and can not be the effective nucleation sites. |
(创新港)
