A two-phase flow model for the cooling of steel by water sprays

Abstract

Bao Steel in Shanghai, P.R.. China, are one of the country's major producers of steel by the continuous casting process. As the hot steel is drawn from the casting machine, it solidifies from its edges inwards. To complete the process of solidification and cool the hot steel, jets of water are sprayed onto the surface of the steel. In this study we consider a two-phase flow model for the heating and vaporisation of the water drops. We concentrate in particular on the non-monotonicity in the measured heat transfer from the steel as a function of the steel temperature. The result of the model is that the vaporisation of a single drop has first to be considered and the resulting behaviour governs the mass and momentum transfer between the two phases. Some simple solutions are then derived for the resulting system of ordinary differential equations. It. appears that, when a vapour layer is present, a Stefan-type problem must be solved to determine the thickness of this layer.