Efficient Prediction of Heat Transfer during Quenching based on a Modified Reynolds-Colburn Analogy

This work presents a study aiming to efficiently predict local rates of heat transfer during quenching of steel pieces in production lines. Laboratory thermal analysis was carried out to determine the heat flux evolution in Jominy-end quenched samples from 850°C(1562°F) and cooled down with an impacting oil jet at 60°C(140°F). The corresponding shear stress and pressure at the solid surface were calculated from the numerical solution of the continuity and Navier-Stokes equations under steady state conditions and isothermal fluid flow. A modified Reynolds-Colburn analogy is proposed in the present work. This analogy postulates a relationship between the heat flux at the solid surface and the sum of the shear stress and pressure imposed over this surface by the fluid flow when heat transfer is absent. The coefficients of this relationship were determined from a regression analysis using the computed fluid flow quantities and the measured heat flux. A high correlation between these variables encourages further studies to generate a data base of these relationships using different types of metal, a wider range of fluid velocity, and different quenchants. Therefore, heat flow can be accurately and efficiently predicted in complex quenching systems via simulation of isothermal fluid flow followed by application of these semi-empirical relationships.