Heat Transfer Analysis during Water Spray Cooling of Steel Rods

A mathematical model has been developed to predict the rod cooling behavior of steel rods under the action of water sprays in the precooling system of a Stelmor machine. The main objective of this work was to study the influence of operation parameters such as rod size, rod speed, rod temperature at the finishing mill, water flow-rate and spray cooling sequence on the final temperature distribution within the rod before it enters into the transformation conveyor. This heat transfer analysis indicates that the spray cooling sequence affects, considerably, the temperature distribution inside the rod. Besides, water flow-rate failures in the spray cooling system disturb drastically its cooling efficiency. Finally, reheating phenomena which go from 150 to 200°C at rod surface are predicted. The calculations were validated with in situ experimental measurements carried out at HyLSA's (Puebla Plant) Stelmor machine. Very good agreement was found between predicted and experimentally measured rod surface temperatures.