高温固体浸漬冷却中の急速冷却開始条件に関する新提案　急速冷却開始熱流束と限界熱流束の関連

抄録

Quenching for high temperature material with liquid is a familiar cooling technique that has been used for a long period to quench metals. Nevertheless, it is no exaggeration to say that the factors that determine the onset of rapid cooling remain unknown. One of the reasons for this is that the phase change during cooling is an unsteady phenomenon with a very short transition time from film boiling to nucleate boiling. This study first focuses on the short period of time immediately after the immersion of a hot solid into a liquid, and derives an exact solution for the heat flux between the solid and liquid under the condition that the heat transfer from the solid to the liquid during this time is dominated by heat conduction. A new proposal is made that the initial temperature of the solid at which the surface heat flux q(t) reaches exactly the critical heat flux qc during immersion cooling at a critical time tc* (Eq. (1)) defined for the cooling water temperature is the temperature at which quench begins. This proposal is applied to the other results of previous studies on the quench temperature during immersion cooling of three different geometries, i.e., sphere, cylinder and plate, and its validity is discussed.