Modeling and simulation of load heating in heat treatment furnaces

The simulation of heat transfer in heat treatment furnace is of great importance for the prediction and control of the ultimate microstructure and properties of workpieces. In this paper a hybrid method based on numerical simulation and analytical equations are proposed to calculate the radiation, convection and conduction heat transfers in heat treatment processes. In the radiation model view factor between the furnace and workpieces, among workpieces are calculated by the exposed surface area over the total surface area. In the conduction model workpieces are classified into lumped capacitance and massive objects. And workpieces are further classified into three basic shapes: sphere, cylinder and sheet for the application of Fourier differential equation. Natural and forced convections are solved by analytical algorithms for aligned and staggered load patterns. Other thermal terms such as gross heat input, heat storage in the furnace, heat storage in load, heat loss from the walls and openings, shell cooling and so on, are included in the furnace model. The optimization of workpiece loading and the thermal schedule are achieved. Two case studies are given for the validation of the models.