3-D Numerical analysis on heating process of loads within vacuum heat treatment furnace

A 3-D numerical heat transfer model integrated with an intelligent PID temperature control subroutine has been developed and employed in the computational simulation of the heating process of typical load within vacuum heat treatment furnace. The transient temperature field within the load was obtained and the relationship among thermal hysteresis time, maximal temperature difference, heating temperature and heating rate was analyzed in detail. The results indicate that the maximal temperature difference within the load, as well as the thermal hysteresis time, decreases with preheating temperature, and increases with heating rate. A set of qualitative relationship guiding the design of thermal schedule for vacuum heat treatment was proposed and thus an optimum heating process was achieved, which could not only reduce the heating time considerably, but also save energy effectively. The simulated heating curves on certain points fitted well with experimental ones, which validated the numerical model used in this study.