Experimental investigation on the impact of ammonia fuel in a low-powered CI engine - A study toward dual fuel engine approach

This study aims to operate a CRDI-equipped single-cylinder CI engine in a dual fuel mode with pilot-ignited WCB fuel and port-injected NH3 fuel. The current study experimentally investigates the influence of various AEFs on performance, combustion, and pollutant emissions of dual fuel engine at peak load (4.14 bar BMEP @ 1500 rpm) conditions with constant speed. The obtained results showed that the AEF was limited due to its inherent combustion properties. Under the aforementioned operating conditions, we achieved a maximum of 44.89% of AEF. The NH3 dual fuel engine achieves a maximum BTE of 29.33%. Moreover, in the dual fuel operation, the combustion switches from the diffusion phase with WCB operation to the rapid controlled phase as the AEF increases. The ICT reduces from 1488 to 1443 K when the AEF increases from 0% to 44.89%, respectively. Although NH3 injection notably decreased the CO2, HC, CO, and smoke emissions by 57.14%, 60.26%, 71.42%, and 67.59%, NOx emissions increased by 16.21% compared with WCB operation. The BSEC of the dual-fuel mode engine is 13.07 MJ/kW-hr, which is slightly higher than the biodiesel operation mode, 12.17 MJ/kW-hr. The maximum ICP, HRR, and ID were increased by 2.6 bar, 4.64 J/deg., and 5 CAD, and CD and combustion phasing were reduced by 9.3 CAD and 7.98 CAD, respectively. However, the turbulence within the cylinder fluctuates significantly, with a COV of IMEP reaching 5.23% at an AEF of 44.89%.