Ammonia Combustion Enhancement

The use of ammonia as a fuel has been recognized as a promising way for various energy and power devices toward carbon neutrality. However, significantly different combustion characteristics of ammonia from conventional fossil fuels pose great challenges to its applications. Among them, the extremely low combustion reactivity of ammonia can lead to poor flame stability and low combustion efficiency, which consequently hinders its direct utilization in existing combustion devices. Therefore, this chapter focuses on the challenge and reviews the emerging attempts in which enhancement strategies have been proposed and tested in laboratory burners or real-scale combustors. Details of the combustion enhancement strategies, such as reactive fuel-cofiring, fuel-cracking, pre-heating, oxygen-enrichment, and combustion auxiliary technologies have been introduced from theoretical, diagnostic, numerical, and technical aspects. These state-of-the-art progresses greatly enable a deeper mechanistic understanding of ammonia combustion enhancement strategies and further development of clean and efficient ammonia combustion technologies, thus facilitating applications of ammonia in practical combustion devices, such as internal combustion engines, aero-engines, land-based gas turbines, furnaces, and boilers.