高温鋼板水スプレー冷却時の冷却特性および熱伝達率

抄録

Water-spray cooling is widely applied to forced cooling of hot steel products. A number of problems, however, still remain to be solved, including heat transfer mechanism, cooling ability, the difference of heat transfer coefficient values between the upper and lower surfaces of a horizontally placed wide plate on which spray is impinged, the effect of scale deposit on heat transfer, and so on.
In order to investigate heat transfer phenomena and cooling abilities of water-spray cooling, plate specimens of carbon steels with dimension of 22.5 to 51mm×550mm×1 000mm, heated at about 630°C, have been water-sprayed. The main results obtaind are as follows:
(1) In the water-spray cooling of the upper and lower surfaces of a horizontally placed specimen with the same water flux W, the value of the heat transfer coefficient α on the upper surface is higher than that on the lower surface in the region of test conditions.
(2) The maximum values of α of the upper and lower surfaces exist in the surface temperature of about 200°C.
(3) The following equation is applicable for describing the quantitative relation of specimen surface temperature θs [°C] and W[l/m² · min] with α [kcal/m²·h·°C].
α= A·W^0.8 · 10^B·θs
where, A and B are constant.