Ahmad Adib Rosyadi  Jeongyeon Choi  Ardhika Setiawan  Ocktaeck Lim

Vol. 31,  No. 4, pp. 330-338, Dec.  2025
10.7464/ksct.2025.31.4.330

Ammonia concentration Dual-fuel combustion Combustion characteristics heat release rate

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This study experimentally examines the influence of ammonia substitution ratio on the combustion behavior of a dual-fuel diesel engine. In the proposed configuration, ammonia was supplied through the intake manifold, while diesel served as the pilot fuel, directly injected into the combustion chamber. Experiments were conducted under constant engine speed and load conditions, with systematic variations in the ammonia energy fraction. Key combustion parameters, including in-cylinder pressure, heat release rate (HRR), ignition delay (ID), and combustion duration, were analyzed to assess the effects of ammonia concentration. The results reveal that increasing the ammonia fraction leads to an extended ignition delay and slower combustion rates, primarily attributed to the low reactivity of ammonia. Nevertheless, at moderate substitution levels, the heat release pattern becomes smoother, and the peak cylinder pressure remains within an acceptable range. Furthermore, higher ammonia content tends to lower the combustion temperature, potentially contributing to a reduction in NOx emissions. These findings demonstrate that ammonia can be effectively utilized as a partial substitute for diesel fuel when its ratio is carefully optimized. Nevertheless, the results remain constrained by the fixed SOI, constant-load operation, and the absence of boost or EGR, indicating that further optimization and wider operating conditions must be explored in future studies.