Water Cooling in Direct Chill Casting : Part 1, Boiling Theory and Control

The intensity of the water cooling in direct chill casting affects the process heat flow and therefore performance of the casting process. The intensity depends on the boiling behaviour on the ingot surface. The basic mechanisms of boiling, the different boiling modes (nucleate, unstable film and stable film boiling) and application to DC casting are discussed. The published effects of water compositional and physical factors (flow rate, temperature etc) on cooling intensity and the methods used to measure these effects are reviewed. A newly developed technique for quantifying heat transfer coefficients and heat fluxes for DC water sprays and new results on the effect of composition, temperature and flow rate are reported. Practical implications for controlling the effect of water cooling on DC casting are suggested.