Evolution and optimization of ammonia spray mixture formation under engine-like conditions

Zhang, Junqing, Zhou, Zhichao, Deng, Jingwei, Li, Xing, Huang, Hongyu, Chen, Danan, Valera-Medina, Agustin ORCID: https://orcid.org/0000-0003-1580-7133 and Li, Jun 2026. Evolution and optimization of ammonia spray mixture formation under engine-like conditions. Applied Thermal Engineering 301 , 131673. 10.1016/j.applthermaleng.2026.131673

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Abstract

In quest to decarbonize mobility, ammonia is increasingly recognized as a promising zero‑carbon alternative fuel. However, its practical application in compression-ignition engines is currently limited by special physicochemical properties, such as high latent heat of vaporization and narrow flammability limits, which pose significant challenges to high-quality mixture formation and combustion stability. This study investigates the spatiotemporal mixing characteristics of liquid ammonia spray under various parameters using constant-volume combustion chamber experiments and large eddy simulation using a non-equilibrium phase change model. The results demonstrate that the non-equilibrium model significantly improves the prediction accuracy. The split injection strategy enhances the mixing effectiveness of liquid ammonia spray. During the dwell period, the liquid core evaporates rapidly, increasing the combustible mixture ratio. However, the high evaporation rate of ammonia can lead to over-dilution in the later stages of spray development, forming extensive low-equivalence-ratio regions. Increasing injection pressure significantly enlarges the combustible mixture volume, which is beneficial for high-load conditions, but also accelerates the transition of the mixture below the lean flammability limit. Consequently, more precise control of ignition timing is required when implementing split injection or increasing injection pressure. This study reveals that balancing “enhancing mixing” with “preventing over-dilution” is critical for optimizing liquid ammonia spray mixture formation, providing guidance for the injection strategies of ammonia engines.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Engineering
Additional Information:	RRS policy applied
Publisher:	Elsevier BV
ISSN:	1359-4311
Date of First Compliant Deposit:	10 June 2026
Date of Acceptance:	26 May 2026
Last Modified:	10 Jun 2026 15:30
URI:	https://orca.cardiff.ac.uk/id/eprint/187460

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