Development of a first-principles hybrid model for large-scale reheating furnaces

•A first-principles hybrid model for large scale reheating furnaces is developed.•The model combines the advantages of the classical zone method and CFD.•The model can correctly respond to transient operating conditions.•The model is capable of real time simulation. This paper details the development of a first-principles hybrid model capable of simulating transient thermal performances of a large scale reheating furnace. In particular, the new modelling approach combines the advantages of the classical zone method of radiation analysis and Computational Fluid Dynamics (CFD) in a robust manner, and overcomes the difficulties of incorporating three-dimensional flow field within a zone method based model. The developed model has been validated with comprehensive experimental data collected during an instrumented bloom trial period that includes a long production delay. The results suggest that the model predictions were in good agreement with the actual measurements, and that the model was able to respond correctly with respect to the encountered production delay during the trial.