Investigation of the effect of air turbulence intensity on NOx emission in non-premixed hydrogen and hydrogen-hydrocarbon composite fuel combustion

In this paper, the effect of air turbulence intensity on NO formation in the combustion of mixed hydrogen-hydrocarbon fuel is numerically studied. The fuels used in this study are 100% H2, 70% H2 + 30% CH4, 10% H2 + 90% CH4 and 100% CH4. Finite volume method is utilized to solve the governing equations. The obtained results using realizable k-ε and β-PDF models show good agreement with other numerical and experimental results. The results show that increasing air turbulence intensity decreases NO concentration in the flame zone and at the combustor outlet. With increasing air turbulence intensity, maximum decreasing of NO at the combustor outlet is for the case of pure hydrogen fuel. It is also found that adding hydrogen to methane rises the peak temperature of the flame.

► The increase of air turbulence intensity (ATI) decreases NO formation. ► By increasing ATI, NO formation is higher at higher hydrogen percentage. ► Pure hydrogen fuel have the highest peak temperature reduction by increasing ATI.