Experimental Study on Local Heat Transfer during Quenching Process by Slot Nozzles

Abstract

Abstract Quenching is widely used in industrial applications. The heat is transferred from the ingots by spray or jet cooling at the secondary cooling zone. In this research work, the effort is focused on the influence of jet inclination on heat transfer in the boiling process, as well as the influence of heat transfer rate by changing the jet velocity through experimental work using Nicrofer sample under 850 ˚C. Different angles of the jet (25°, 45°, 65°, 90°) and flow velocities (3.5 m/s, 4.8 m/s, 7.8 m/s, 12.0 m/s) were arranged in these experiments respectively. The results indicated that due to the strong cooling effect of jet quenching the Leidenfrost point was not captured. Both the jet angle and jet velocity played important roles in promoting the cooling process. The smaller the jet angle, the faster the quenching rate. The angle of 25° presented the most optimum cooling effect. The higher the jet velocity, the shorter the cooling time. For the maximum jet velocity in this experiment v=12.0m/s, DNB-temperature even was not identified.