Numerical simulation of fluid flow and heat transfer in an industrial continuous furnace

We present a three-dimensional computational study of the transient heat transfer and turbulent fluid flow inside an arc-welding electrode continuous furnace. The model is implemented in FLUENT, a finite volume commercial code. Large difference in the length scales of the electrodes and the furnace, movement of the electrodes, and existence of various modes of heat transfer are the major factors influencing the accuracy and efficiency of the simulation. Two modeling strategies are used to overcome these difficulties. First, the electrode geometry and material composition are simplified using a thermally equivalent model. Second, the electrode movement inside the furnace is avoided by implementing time-dependent boundary conditions applied to a fixed domain. A fairly close agreement is obtained in comparing the load's temperature history against the experimental data with an absolute relative difference below 2.7%. The space between the electrode trays in the furnace is very limited. The analysis shows that the input air does not circulate effectively between the trays. This lowers the thermal efficiency of the furnace and leads to uneven treatment of the electrodes. The present study provides guidelines to improve future furnace designs.