A Review of Ammonia Combustion and Emissions Characteristics in Spark-Ignition Engines and Future Road Map

Ammonia (NH<sub>3</sub>) is gaining recognition as a viable “green” transportation fuel due to its zero-carbon characteristic, its high energy density and its widespread availability. However, NH<sub>3</sub> has a high auto-ignition temperature, resulting in potential emissio...

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Bibliographic Details
Main Authors: Vikas Sharma, Angad Panesar, Guillaume de Sercey, Steven Begg
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Energies
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Online Access:https://www.mdpi.com/1996-1073/18/1/41
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Summary:Ammonia (NH<sub>3</sub>) is gaining recognition as a viable “green” transportation fuel due to its zero-carbon characteristic, its high energy density and its widespread availability. However, NH<sub>3</sub> has a high auto-ignition temperature, resulting in potential emissions of NO<sub>x</sub> and unburned NH<sub>3</sub>. Addressing combustion challenges requires innovative solutions, such as the application of combustion promoters to enhance NH<sub>3</sub> combustibility. This review article focuses on the compatibility of NH<sub>3</sub> as a fuel for spark-ignition (SI) engines, examining its combustion under various modes including pure NH<sub>3</sub> combustion, gasoline blends, NH<sub>3</sub>/hydrogen (H<sub>2</sub>) blends, and NH<sub>3</sub>/natural gas blends in single or dual-fuel configurations. The formation of nitrogen oxides (NO<sub>x</sub>) and slip-NH<sub>3</sub> is explored to understand emissions species such as NO and N<sub>2</sub>O. Additionally, the article highlights the limitations of NH<sub>3</sub> as a fuel for SI combustion. The comprehensive discussion provided in this review aims to fill a critical gap in the literature regarding NH<sub>3</sub>’s feasibility as a zero-carbon fuel for SI engines, particularly in the maritime sector. By offering insights into NH<sub>3</sub> combustion characteristics and emissions profiles, the article seeks to provide a roadmap for leveraging NH<sub>3</sub> as a suitable non-carbon fuel to decarbonize the marine sector and advance global sustainability goals.
ISSN:1996-1073