Estimation of heat transfer coefficient during quenching steel in water

Abstract

The paper presents the process of two-dimensional axisymmetric quenching of cylindrical samples in water at 40 °C. Experimental work consists of quenching three dimensionally different cylindrical probes. The dimensions of the probes are: ø25x50, ø50x150 and ø75x225 mm. Three measuring points are 1.5 mm below the cylinder surface positioned at the cylinder height, whereas the fourth measuring point is in the center of gravity of the cylinder. The quenching was conducted in strict controlled rate of water flow at the cylinder head. The problem of the task belongs to inverse problems of heat conduction, or ill posed problems, so that the solution to the problem leads to a sufficiently accurate estimate of the unknown heat transfer coefficient, imposed on the outer surface of the cylinder. Computer model solutions use experimental results of temperature measurements to minimiže errors between computer calculations and measured temperature values in the same place. The selected solution algorithm is a hybrid algorithm that consists of a combination of three different algorithms of solution, connected into a single unit.