Study of the effect of wall temperature and oxidant structure on temperature distribution and NO emission in non-premixed combustion furnace

The aim of this study was to investigate the effect of thermal condition of the furnace wall and oxidant structure on the NOx emission and temperature distribution inside the non-premixed combustion furnace. For this purpose, non-premixed combustion furnace simulations have been performed using OpenFOAM software. In numerical simulations, the standard k-ε turbulence model, modified EDC combustion model, DO radiation model and GRI3.0 chemical kinetic are used. In order to analyze the results of numerical simulations, chemical calculations using well stirred reactor have also been considered. According to the obtained results, increasing the furnace wall temperature to reach thermal insulation conditions leads to a significant increase in the average and maximum temperature inside the combustion chamber and leads to the transition from flameless combustion regime to high temperature regime. In addition, the replacement of carbon dioxide with nitrogen leads to a significant reduction in combustion chamber temperature due to the physical and chemical differences between the two species. According to the results, increasing the furnace wall temperature, despite reducing the heat loss, leads to a significant increase in the amount of NOx in the high temperature combustion regime. The use of CO2 instead of N2 as an oxidizer can be considered as a way to reduce heat loss while reducing the amount of NOx emitted from the non-premixed combustion furnace.