Ammonia marine engine design for enhanced efficiency and reduced greenhouse gas emissions

Xinyi Zhou; Tie Li; Run Chen; Yijie Wei; Xinran Wang; Ning Wang; Shiyan Li; Min Kuang; Wenming Yang

doi:10.1038/s41467-024-46452-z

Ammonia marine engine design for enhanced efficiency and reduced greenhouse gas emissions

Nat Commun. 2024 Mar 7;15(1):2110. doi: 10.1038/s41467-024-46452-z.

Authors

Xinyi Zhou^{1

2

3}, Tie Li^{4

5}, Run Chen^{1

2}, Yijie Wei⁶, Xinran Wang², Ning Wang², Shiyan Li^{1

2}, Min Kuang⁷, Wenming Yang⁸

Affiliations

¹ State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
² Institute of Power Plants and Automation, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
³ Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore.
⁴ State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai, People's Republic of China. litie@sjtu.edu.cn.
⁵ Institute of Power Plants and Automation, Shanghai Jiao Tong University, Shanghai, People's Republic of China. litie@sjtu.edu.cn.
⁶ National Engineering Research Center of Special Equipment and Power System for Ship and Marine Engineering, Shanghai, People's Republic of China.
⁷ Faculty of Maritime and Transportation, Ningbo University, Zhejiang, People's Republic of China.
⁸ Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore. mpeywm@nus.edu.sg.

Abstract

Pilot-diesel-ignition ammonia combustion engines have attracted widespread attentions from the maritime sector, but there are still bottleneck problems such as high unburned NH₃ and N₂O emissions as well as low thermal efficiency that need to be solved before further applications. In this study, a concept termed as in-cylinder reforming gas recirculation is initiated to simultaneously improve the thermal efficiency and reduce the unburned NH₃, NO_x, N₂O and greenhouse gas emissions of pilot-diesel-ignition ammonia combustion engine. For this concept, one cylinder of the multi-cylinder engine operates rich of stoichiometric and the excess ammonia in the cylinder is partially decomposed into hydrogen, then the exhaust of this dedicated reforming cylinder is recirculated into the other cylinders and therefore the advantages of hydrogen-enriched combustion and exhaust gas recirculation can be combined. The results show that at 3% diesel energetic ratio and 1000 rpm, the engine can increase the indicated thermal efficiency by 15.8% and reduce the unburned NH₃ by 89.3%, N₂O by 91.2% compared to the base/traditional ammonia engine without the proposed method. At the same time, it is able to reduce carbon footprint by 97.0% and greenhouse gases by 94.0% compared to the traditional pure diesel mode.

Abstract

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