Investigation of the role of methane injection timing and pressure on engine performance, emissions and environmental impact in a diesel engine

Methane diesel dual-fuel engines are gaining increasing interest because they offer lower emissions and higher efficiency compared to conventional single-diesel fuel engines. However, due to the low combustion efficiency and combustion stability of the methane-diesel dual-fuel application, there are still unresolved issues that need to be addressed. In this study, the effects of methane gas injection timing and pressure on engine performance and exhaust emissions are investigated in order to overcome problems related to the application of methane gas in dual-fuel engines. Additionally, the environmental and economic impacts of the exhaust emissions resulting from combustion are analyzed. The study is conducted with 5 different methane gas injection timings (25, 35, 45, 55, and 65 degrees after TDC) and 4 different methane gas injection pressures (1 bar, 1.5 bar, 2 bar, and 2.5 bar). In the experiments, the engine torque (5 Nm) and operating speed (1850 1/min) are kept constant. The results show that increasing the methane gas injection pressure (GIP) from 1 bar to 2.5 bar and delaying the methane gas injection timing (GIT) from 25° aTDC to 65° aTDC leads to an average reduction of 8.5% in SFC values and a 4% increase in thermal efficiency compared to diesel operation. Similarly, increasing GIP and delaying GIT results in an average reduction of 46% in NO emissions and an average reduction of 48% in soot emissions.