Results of Heat Transfer Coefficient Estimation during the Quenching of Cylindrical Samples in Aqueous Solutions

Summary The paper presented the results of the heat transfer coefficient estimation in the process of two-dimensional axially symmetric quenching of cylindrical steel samples in aqueous 40  C solutions. One aqueous solution had 5% and the other one 25% of Aquatensid BW. Such solutions allow the rate of cooling of steel quenching less than the one in clean water, and higher than the one in thermal oils. The experimental setup consisted of quenching three dimensionally different cylindrical probes into two different quenchants. The position of the thermocouples inside each probe, the aqueous solution streaming around the probe and the construction of the cooling bath conditioned the thermodynamic setting of the problem. The mathematical setting of the problem was based on thermodynamic assumption of two-dimensional axially symmetric, nonlinear and nonstationary heat conduction. The position of the thermocouples conditioned the inverse way of the problem solving and it led to an approximate estimation of an unknown heat transfer coefficient. During the task solving the compute model used the experimental results of the temperature measurements for the minimisations of the square deviation between the calculated and measured temperatures in one position and moment of time. The analysis of the obtained results during the quenching of cylindrical probes in aqueous solutions was compared to the results obtained when quenching in