Optimum Blending Hydrogen Ratio in Spray Combustion to Reduce Emissions of Nitrogen Oxides

This study examined the effects of adding hydrogen to flammable liquid fuel droplets on emissions. It was found that an optimal mixing ratio with hydrogen can reduce the amount of NO in the reaction zone, which is the area where the primary combustion reactions occur. N-pentane is burnt in air enriched with different amounts of hydrogen, and the effects of the amount of hydrogen in the air on the combustion and emission parameters are investigated numerically. The combustion is modelled with the PDF/mixture fraction, and standard twoequation turbulence models and thermal NO models are used for this modelling. The determination of the optimum H2 blending ratio is evaluated after the estimation results. It is evident that the addition of H2 led to an increase in spray flame temperatures. As a result, the addition of H2 increases the combustion performance of n-pentane. The emissions evaluation results show that a blending ratio of 20% H2 reduces CO emissions at the combustion’s reaction zone and also results in a decrease in the mixture fraction. There is an increase in NO emissions due to the increase in spray flame temperatures. Combustion under air conditions containing 20% H2 by volume resulted in the highest temperature levels reaching 2130 K, while the reduced NO levels decreased to approximately 11.3%. The thermal NO model, when combined with the combustion model, provides a sufficient level of agreement with the experimental data.