Abstract
The water spray cooling is widely used in many industrial processes like metallurgy, microelectronics, nuclear safety and aerospace engineering. The metallurgical industry uses spray cooling for quenching of steel and cooling of strands in continuous casting process. A parameter which has a great influence on microstructure and residual stresses in steel specimens is the heat transfer coefficient. This parameter allows to control the cooling rate and thus allows to improve and optimize productivity and quality of the products. There are many parameters affecting the heat transfer coefficient, which include the physics of the cooling process, the properties of cooling material and properties of the cooling medium. In this paper an experimental study has been made to determine the effect of water spray cooling parameters on the heat transfer from a hot metal surface. The investigated parameters are water flux, the distance of the spray nozzle from the cooling surface and the spray pressure. The experimental sample is metal cylinder of 20 mm in diameter and 20 mm long, which has been heated in a resistance heater furnace to about 530oC and then rapidly and symmetrically cooled by water spray using the full cone water nozzle. To measure the temperature inside the sample, three fast response thermocouples have been used. The heat transfer coefficient has been determined by the boundary inverse problem of heat conduction. A finite element method has been applied to solve the problem. As a result, cooling curves expressing the heat transfer coefficient as a function of surface temperature have been obtained.