Spray Cooling Heat Transfer and Calculation of Water Impact Density for Cooling of Steel Sheet Materials by Inverse Process Modelling

Modern steel grades require accurate temperature control during processing. The cooling section technology has to deliver prescribed cooling rates while fulfilling specific constraints, e.g. on the minimum surface temperature. For all material thicknesses, numerical cooling system set value prediction is advantageous and above 10 mm, the possible cooling rates and the experimental parameter determination are limited by physical constraints. Laboratory measurements provide quantitative experimental data on the heat transfer coefficient (HTC) depending on the cooling system parameter water impact density and the temperature difference. The desired final material properties determine temperature control and cooling rate. This information is used to predict the optimum cooling section set values for a specific cooling task. The inverse modelling calculations use a simple cooling section process model. Illustrative examples for optimum cooling of strip or sheet material using water spray cooling demonstrate the approach. Additionally, the physical limitations due to the finite heat conductivity of the strip are calculated and discussed.