Experimental and kinetic modeling study on laminar burning velocities and ignition delay times of NH3/PODE3 blends

• Ignition delay times of NH 3 /PODE 3 blends under diverse conditions were determined. • Laminar burning velocities of NH 3 /PODE 3 blends under wide conditions were measured. • A detailed mechanism for NH 3 /PODE 3 blends has been developed and validated. • Flame instability of NH 3 /PODE 3 blends was discussed. Ammonia–polyoxymethylene dimethyl ether 3 (PODE 3 ) dual fuel mode shows great potential in enhancing ammonia combustion performance, reducing carbon-related and pollutant emissions, and promoting the widespread application of ammonia-fueled engines. In this study, the ignition delay times (IDTs) of NH 3 /PODE 3 blends were measured using a rapid compression machine (RCM) within a wide temperature (T eff ) range at elevated pressures (P eff ). Moreover, the laminar burning velocities (LBVs) of NH 3 /PODE 3 blends were determined employing a constant-volume combustion vessel at wide initial pressures, temperatures, and ammonia molar ratios (AMRs). The outcomes demonstrate that the incorporation of PODE 3 conspicuously shortens the IDTs and augments the LBVs of NH 3 . Based on these data, a detailed chemical reaction mechanism for NH 3 /PODE 3 blends has been developed, encompassing 319 species and 2015 reactions. This proposed mechanism was meticulously validated against IDTs, LBVs, and major species mole fraction profile data over an extensive spectrum of experimental conditions, covering not only pure NH 3 and pure PODE 3 but also NH 3 /PODE 3 blends with diverse ammonia fractions. The results evince a high degree of prediction accuracy when applying this mechanism, thereby corroborating the efficacy and appropriateness of the mechanism for CFD simulations in NH 3 –PODE 3 dual fuel engines. Pathway analysis and sensitivity analysis were also conducted. The results demonstrate that the H-abstraction reactions of PODE 3 by NH 2 radical, R9: PODE 3 + NH 2 =PODE 3 B + NH 3 and R10: PODE 3 + NH 2 =PODE 3 A + NH 3 , are sensitive only under the condition of AMR = 92.5 % and 1.5 MPa with respect to IDTs. The chain branching reactions, R#1: O 2 + H = O + OH, exhibits the highest sensitivity coefficients for LBV. The NNH radical plays a crucial role in both IDTs and LBVs of NH 3 /PODE 3 blends, whereas the CH 3 radical is more prominent at rich regime for LBVs. The results further indicate that increasing AMR can enhance the flame stability of NH 3 /PODE 3 blends.