Modeling Ammonia-Hydrogen-Air Combustion and Emission Characteristics of a Generic Swirl Burner

Abstract

The combustion process of both pure NH3 and a NH3/H2 fuel blends is here analyzed using two kinetics processors, i.e., Chemkin-Pro-and CANTERA: detailed kinetic mechanisms have been tested and compared in terms of laminar flame speed and ignition delay time (IDT) with the aim to identifying the most suitable ones for the evaluation of NOx emissions. The generic swirl burner being used in Cardiff University's Gas Turbine Research Center has been considered as validation test case. In addition, this paper presents an experimental campaign followed by a computational fluid dynamics (CFD) approach for the assessment of NOx emission using axisymmetric Reynolds-Averaged Navier–Stokes (RANS) simulations, leading to a significant reduction of the computational time. Different pressures and mass flow rates are evaluated to understand correlations of NOx formation for pollutants reduction purpose. A direct comparison between experimental and numerical results is carried out in terms of flow field, flame shape, and NOx emissions. Results show that the increase in pressure from 1.1 bar to 2 bar results in reduction of NOx emissions from 2515 ppmv to 885 ppmv, also indicating guidelines for using a simplified RANS analysis, which leads to improved computational efficiency, allowing wide sensitivity and optimization analysis to support the design development of an industrial combustion system.