Numerical study on effect of nozzle diameter on plate cooling in run out table of hot plate rolling process

The design of cooling systems for running hot steel plates has received much attention because the mechanical and/or metallurgical properties of final products are greatly influenced by the cooling capacity of the system. Thus many steel makers have largely concentrated on simply increasing the cooling water supply capacity of the system. Some researchers believe that plate cooling is a type of thermal communication between the hot plate and the cooling water or the atmosphere, so they have emphasized the importance of thermal conditions such as the cooling water temperature or air humidity. Actually the cooling process is governed by the basic physics of boiling heat transfer between the hot steel plate and the cooling water. Therefore steel makers should be more concerned about the influence of the design parameters of cooling facilities on the boiling phenomenon rather than the simple increase of the cooling water flow rate. In this study, when the diameter of the nozzle supplying cooling water is changed, its effect on boiling heat transfer has been investigated numerically. The average heat flux, the Leidenfrost-steam-layer thickness, the temperature drop and so on were investigated according to nozzle diameter.