Numerical study of the effect of fuel injection timing on the ignition delay, performance parameters and exhaust emission of gas/dual fuel diesel engine using Computational Fluid Dynamics

Today, due to the various usage of compression ignition engines in urban transportation, as well as the need to reduce exhaust emissions and control fuel consumption, the use of alternative fuels has become common in diesel engines. Gaseous fuel is one of the most common alternative fuels that can be used in diesel engines. The utilization of alternative fuels in compression ignition engines requires the study of the combustion quality and the type of flammable mixture formation in the combustion chamber. Fuel injection parameter play a significant role in the combustion quality of dual-fuel diesel/gas engines. The injection timing and gaseous fuel mixing percentage together are among the parameters associated with fuel injection. In order to investigate the effect of fuel injection timing on the combustion quality of dual-fuel diesel / gas engines, a study was conducted. In this research, dual-fuel diesel engine is evaluated at two different speeds using the CFD method. To this research, three modes were selected for the fuel IT: BTDC 22°, BTDC 18° and BTDC 14° and three modes for gaseous fuel mixing percentage: 90%-10%, 85%-15% and 75%-25%. The results of numerical studies showed that with increasing fuel injection timing in a diesel / gas dual-fuel engine, the combustion chamber temperature and cylinder pressure peak (PCP) was increased. Increasing the IT also increased the ignition delay, diesel Knocking and distanced the PCP curve from TDC. The IMEP and output torque increased by 16% as the PCP increased. As the mass flow rate of pilot fuel increased, the ignition delay decreased, causing the PCP to fall. The output torque and indicator power decreased by 17% and 70% respectively. Reducing the fuel IT at high speed, the indicator power improved and the emission results showed that the IT advancing increased the NOx and CO2 by 31% and 16% respectively, indicating improved combustion quality in the dual-fuel diesel engine.