トンネル型多孔面のプール沸騰特性に及ぼす諸因子の影響

抄録

Heat transfer performance of aluminum porous surfaces with fine tunnel structures is investigated experimentally. We have made eight types of porous surfaces (Al: No.1~6 and Cu: No.7~8 as reference). Porous surface No.4 has similar specification with THERMOEXCEL and is used as a reference surface as well as smooth surface. Fluorine-based refrigerant HFE-7000 is used as a working fluid. Absolute pressures cited are 0.10MPa, 0.14MPa, 0.18MPa, respectively. Porous surfaces No.1 has a large number of nucleation points that is more than 300 at low superheat region of 0.1Mpa. On the other hand, it is about 10 for smooth surface and about 40 for reference surface No.2. Furthermore, we do not observe any hysteresis for No.1. Porous surface No.2 has the highest heat transfer performance among tested aluminum surfaces. The heat transfer is higher than 11 times of smooth surface and 6.5 times of reference porous surface No.4 at 80kW/m2 of 0.14MPa. Optimum fin pitch of porous surface seems to be around 300μm. When the fin height is too large compared with standard specification, heat transfer performance is significantly lowered. There is no significant difference in heat transfer performance. On the other hand, there is a notable difference in performance between copper and aluminum porous surfaces at the high heat flux region. Although heat transfer coefficient of copper porous surface increases with increment of heat flux, that of aluminum porous surface comes to an upper limit for increasing heat flux.