Thermal interaction which is caused by explosive boiling of water droplet in contact with hot molten tin was investigated, paying attention on the influences of the tin tempera-ture T
tin and the water temperature T
water together with the impact Weber number We. The results were summarized as follows. (1) Ttin, of lower boundary of thermal interaction zone (TIZ) is almost constant at about 290°C for a larger We than about 70, independent of T
water. (2) The corresponding contact interface temperature is around 275°C and almost agrees with (27/32) T
crit, or the spontaneous nucleation temperature, where T
crit=647 K (=374°C). (3) T
tin of upper TIZ boundary increases from around Tcrit to above 500°C as Twater decreases. (4) Twater of upper TIZ boundary is about 80°C. (5) For the woodsmetal-water system, in spite of a very low melting point of 78°C, the woodsmetal temperature of lower TIZ boundary rises up to about 350°C because of a low thermal conductivity of woodsmetal. (6) The Leidenfrost temperature is about 195°C for water droplet on solid tin, which has a melting point of 232°C, and appreciably lower than Ttin of lower TIZ boundary.
In conclusion, the present results support the spontaneous nucleation temperature concept by Fauske & Henry, as far as extremely energetic thermal interaction is concerned.
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