Computationally efficient alternative to a full-scale transient simulation of a reheating furnace

Abstract: Reheating of steel slabs in a reheating furnace is an intermediate step in the long and complicated process of steel making. Reheat furnaces heat the slabs to about 1200 \ub0C, which makes the steel suitable for hot rolling. During this reheating process temperature uniformity within the slab is very important. A detailed understanding of the reheating process is hence, important both from the perspective of product quality and energy use. Unfortunately, the extreme conditions inside the furnace do not allow for a detailed experimental investigation. Numerical tools like Computational Fluid Dynamics are useful in such situations, but full-scale transient models often lead to unpractically high computational costs. In this paper, a Truncated Transient Slab Model is validated, which is capable of predicting the transient behaviour of the slab during reheating in a computationally efficient way. This is accomplished by coupling two different models: a steady-state model of the complete furnace and a transient model of the truncated domain around a single slab. The truncated domain replicates the flow conditions of a full-scale transient model in a much smaller domain. The advantage of this modelling approach when compared to full-scale transient models is a significant reduction in simulation time (just 4 days) while maintaining a high grid resolution. Compared to the experiments, the simulations have an average accuracy of 4\u20135% for the entire range of reheating temperatures (28\u2013 1200 \ub0C) for both the slab surface and the core. The error on the slab drop-out temperature was about 2% at a measured temperature 1185 \ub0C