On the Heat and Mass Transfer Modeling to Simulate Quenching Heat Treatment Process

In this article, discussions pertaining to a robust computational methodology to simulate the immersion quenching heat treatment process are presented.  Computational Fluid Dynamics (CFD) study carried out using the commercial CFD code AVL FIRE v2011®, performs coupled computations encompassing both the fluid domain, containing the quench bath, and the immersing solid structure(s) through a novel interface coupling procedure, which allows data exchange such as of phase change rates, convection coefficients, heat fluxes  etc across the domain boundaries. In the fluid domain, the boiling multiphase flow, triggered by the dipping hot solid part into a sub-cooled liquid bath, is handled using an Eulerian multi-fluid method.  The ensuing heat and mass transfer effects are modeled based on the different boiling modes, film or nucleate boiling regime, prevalent in the system. In the solid domain, solutions to the energy equation provide the necessary temperature evolution dynamics. Separate computational domains constructed for the quenched solid part(s) and the fluid (quenchant) flow are numerically coupled at the interface of the solid-fluid boundaries leading to a tightly coupled multi-domain system. The discussed quenching procedure is applied to a wide variety of quenching scenarios involving immersion cooling of trapezoidal blocks, engine cylinder heads and other complex structures. Results in the form of temperature evolution in the solids, volume fraction distribution in the fluid domain are compared with the experimental recordings, wherever available.  Elaborate descriptions of the numerical and physical models employed in the procedure are provided. Extended applications of the current modeling procedure are also noted.