Study on the Combustion Characteristics of Ammonia/Hydrogen Fuel Jet Ignition in Marine Engines

To break through the limitations ol ammonia combustion in engines and promote elficient and rapid combustion ol ammonia, a method lor igniting ammonia lucl using a hydrogen jet llame is proposed. By supplying hydrogen to the active pre-combustion chamber and premixing ammonia/hydrogen luel in the inlet tract, stable and efficient combustion ol ammonia in a large bore marine engine is achieved. The ellects ol inlet gas temperature, hydrogen addition ratio and main combustion chamber equivalent ratio on the ignition characteristics ol the ammonia-hydrogen lucl arc investigated based on numerical simulation methods and improved Otomo ammonia/ hydrogen mechanism. Results show that jet llamcs can develop the thermodynamic environment and high active heat jets required lor combustion in the main combustion chamber. At an equivalence ratio ol 0. 4 and no hydrogen addition, thin combustion ol ammonia-lueled engines can be achieved at an inlet temperature ol 450 K. Jet ignition has a more signilicant effect on flame development at lower hydrogen addition ratios; increasing the hydrogen addition ratio to 10. 0% advances the combustion phase by 18°, but there is an increased risk of detonation; at an inlet temperature of 320 K and a hydrogen addition ratio of 2. 5%, the main combustion chamber can ignite normally at a minimum equivalence ratio of 0. 45, but there is a slight increase in indicated thermal efficiency as combustion approaches the theoretical air-fuel ratio. The combustion mode of active prc-combustion chamber hydrogen jet ignition shows promising potential for achieving efficient and fast combustion in ammonia engines. © 2024 Xi'an Jiaotong University. All rights reserved.