Meng Xiangyu, Miao Menglan, Zhang Xuanrui, Li Yuqiang, Long Wuqiang, Bi Mingshu
School of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning 116024, China.
School of Energy Science and Engineering, Central South University, Changsha 410083, China.
Sci Total Environ. 2025 Feb 10;964:178587. doi: 10.1016/j.scitotenv.2025.178587. Epub 2025 Jan 24.
Ammonia (NH) holds promise as a carbon-free fuel. Blending it with highly reactive fuels could efficiently alleviate issues such as slow burning rates and narrow flammability ranges. Ethanol (CHOH) offers the advantage of carbon neutrality and has a high-octane rating. Ammonia cracking is an efficient way to on-line hydrogen generation, mitigating storage and transportation concerns. This work aims to research the combustion of ammonia/ethanol blends with ammonia cracking. To achieve highly accurate predictions for these fuel blends, a detailed combustion chemical kinetic mechanism with 126 species and 1453 reactions for NH, CHOH, H, and their blends was developed. This mechanism underwent extensive validation against experimental measurements reported in the literature, including laminar burning velocity (LBV) at initial temperatures ranging from 298 to 473 K, pressures from 1 to 5 atm, and equivalence ratios from 0.5 to 1.6, as well as ignition delay time (IDT) at initial temperatures from 820 to 2500 K, pressures from 1.2 to 60 atm and equivalence ratios from 0.3 to 1. Additionally, a simplified mechanism containing 73 species and 449 reactions was developed using a couple of mechanism reduction methods. The effect of adding ethanol on LBV was investigated under laminar burning conditions, and the decoupling of thermal, chemical, and transport effects was studied. Considering the complexity of fuel composition for the blends, a modified Metghalchi-Kech power law formula was performed, which exhibits a highly linear correlation with LBVs of the blended fuels when coupled with the sum of maximum mole fractions for OH/O/H/NH. Furthermore, NO and NO behaviors were also investigated for various fuel blends and initial conditions. It was found that the a higher NH cracking ratio tends to help to reduce the NO generation, and thermal NO is higher at elevated initial temperature and pressure. NO is easily produced under lean-burn condition.
