CFD modeling of a flameless furnace: comparative evaluation of turbulent combustion models with two software on a HPC platforms

Object of this study is a HEC furnace (High Efficiency Combustion) of a semiindustrial scale, equipped with a pair of NFK burners, of 1 MWt power fed by natural gas, for which was conducted in campaign of IFRF measures. The experimental data, required for the model validation, and the specifications the application, were provided by the CSM Materials Development Center. The computer code ANSYS Fluent CFD has been made available by the ENEA Centre Research, while the STAR-CCM+ code has been made available in version POD (Power On Demand) from CD-Adapco. The computing resources and its technical support were provided by the computing infrastructure HPC (High Performance Computing) which belong to CRESCO/ENEAGRID and his staff. This computing infrastructure was realized by ENEA using a programs national and European research. The analyzed burners have a strong jet central air, preheated to high temperature, and two side weak jets of fuel at room temperature. For these types of furnaces were already developed some RANS models, based on the approach that has been taken as a reference for the modeling implemented. The scope of this work was to compare different turbulent combustion models based on the approach RANS and compare the results obtained with the two different simulative platforms. For both software, starting from the available technical drawings, furnace and burner geometry of lances were created. In particular, one of the applications involves the use of regenerative burners NFK in the reheating furnaces of the steel industry. The present work is part of a research between the University of Sannio, ENEA Portici Research Center (National Agency for New Technologies, Energy and Sustainable Economic Development), Arcades, the Development Center CSM materials and CD-Adapco Company. The goal is the development of a CFD model finalized to the prediction of operation of the furnaces operating in scheme flameless by the use of two of different simulation platforms. One of the planning techniques most used for the alternative combustion systems development is the CFD simulation applied to the reagents systems; the numerical simulation of turbulent reactive flows has realized meaningful progress due to the improvement in the modeling of physical systems. The development of robust and efficient numerical algorithms, the evolution of the available processing power and the introduction of detailed kinetic schemes able to describe accurately the chemistry of the processes, applied on the real system, allow the CFD simulation to observe phenomena not otherwise easily measured. Therefore, the CFD simulation versatility makes itself an extremely important tool, both in the design of new equipment, both for their subsequent optimal run. A deepen description of a turbulent combustion system represents an extremely complex task and an accurate representation of the chemical phenomena requires the use of kinetic models that include hundreds of thousands of species and reactions. In addition, there is to take into account the difficulty of modeling the interaction between the turbulent flows and chemical reactions in a combustion chamber.