Estudo da transferência de calor e obtenção de dados de referência para simulação numérica de sistema de resfriamento de cilindros de trabalho da laminação a quente

Abstract

Roll cooling is one of the important processes in the Hot Rolling, can highlight two points. The first is the wear of the roll, where the high temperature influence on its durability in the mill. The second is the thermal expansion of the roll where it is critical to both the shape and dimensional tolerance for the product. For the cooling is done well, it is necessary that the jets of water are conveniently distributed throughout the body and the roll pressure is adjusted according to need, ie, enough to break the film of water vapor, so that water acts directly on the roll body. Therefore, determining the coefficients and the regimes of heat transfer, which occur during the incidence of water jet on the surface at high temperature, are essential for the control system. Throughoutthis paper we present experimental and numerical studies of the effects of cooling water jet fan-shaped on a roll prototype to high temperatures ranging from 50 to 350ºC. The thermal characteristics were examined by means of cooling curves at different test conditions. The numerical analysis was performed using the inverse heat conduction. The results contributed to a better understanding of the modes of heat transfer involved during cooling of rolls heated to high temperatures, and to improve the modeling and design of cooling systems for hot rolling. The results showed that the pressure, nozzle type and the length spray jet influence the efficiency of roll cooling. Maximum value found for the coefficient of heat transfer was 6.0 kW/m2.°C, showing a 14.3% difference between the center and edge of the fan.