被膜金属円柱の浸漬冷却特性

（被膜による急冷促進とその限界）

抄録

Monde and Mitsutake [1] recently proposed a new idea for immersion cooling that the quench starts when the surface heat flux q(t) during the immersion cooling reaches exactly the critical heat flux q_c at a critical time t_c* depending on a couple of solid and liquid. This time t_c* during immersion cooling of liquid nitrogen (LN₂) appears t_c* = 1.4 ~ 2.4 ms for some rare sphere solids. Monde and Mitsutake [2] expand their idea for the immersion cooling of Al sphere coated by a thin Teflon film and explain the reason that the temperature at which its quench occurs, shifts to higher temperature with increase in the thickness of Teflon. This study firstly focuses on the short period of time immediately after the immersion of a cylinder coated by thin film into a liquid and then derives an exact solution for the temperature during the immersion cooling. It reveals for about 10 ms after a contact of the Cu cylinder coated by Stycast with liquid Nitrogen(LN₂) that the temperature for the cylinder is uniformly kept at a constant temperature, while the surface temperature on Stycast contact with LN₂ drops at a moment of their contact until a certain temperature which is determined by both initial temperatures of the cylinder and LN₂ before their contact and then the temperature in Stycast film largely changes with time. In addition, the quench starts within the time of t_c* = 10 ms, after the immersion of the Cu cylinder coated by Stycast into LN₂．The mechanism that the coated film makes the temperature, at which the quench starts, higher, is clearly explained.