Optimization of hydrogen-enriched diesel/n-Amyl alcohol-fueled engine to meet emission standards through varying nozzle opening pressure and static injection timing

Important injection parameters such as fuel injection timing (FIT) and fuel injection pressure (FIP) on different piston bowl geometries substantially impact the performance, emissions, and combustion characteristics of a common rail direct injection engine. The aim of this study deals with the effects of piston bowl geometry (hemispherical bowl [HSB], troded bowl [TRB], and re-entrant bowl [REB]), FIP (200, 220, and 240 bar), and variable FIT (20, 24, and 28°bTDC) with hydrogen-diesel/1-pentanol (B20) (80% diesel and 20% pentanol) with a constant flow rate of hydrogen at 12 Lpm. Furthermore, to decrease emission standards and energy consumption, biodiesel and hydrogen are the ideal substitutes for conventional fuels. REB outperforms HSB and TRB in terms of brake thermal efficiency (5.67%) and hydrocarbon (8% reduction), increasing the FIP at full load (240 bar). However, with the increase in the FIP in the REB, a slight reduction in nitrogen oxide (NO_x) emissions (2%) is observed. With an increase in FIP in the case of REB, net heat release rate, peak pressure (in-cylinder), and rate of pressure rise all rise significantly by 3.4%, 4.2%, and 2.3%. NO_x emissions are marginally enhanced with higher FIP and advanced FIT. It is found that changing the piston shape and FIP simultaneously is a potential alternative for improving engine performance and lowering emissions.