Utilization of renewable and sustainable diesel/methanol/n-butanol (DMB) blends for reducing the engine emissions in a diesel engine with different pre-injection strategies

In the face of the severe energy crisis and environmental crisis, actively finding and using alternative fuels rationally is one of the main ways to alleviate energy shortage and environmental pollution. Biomass fuels are alternative fuels with good development prospects. The addition of oxygenated biofuels can reduce the soot emission, but increase the nitrogen oxides (NOx) emission. Multiple injection strategies can be used to reduce the NOx emission. Therefore, this paper was mainly aimed at the parameters investigation of a medium-speed marine four-stroke diesel engine fueled with diesel/methanol/n-butanol (DMB) blended fuel. The effects of pre-injection (including pre-injection fuel timing (PT) and pre-injection fuel mass ratio (PMR)) on the engine combustion, performance, and emission parameters were obtained. In addition, an orthogonal test design was used to optimize the PT and PMR to determine the optimal combination. The simulation results showed that advancing PT and increasing PMR could increase cylinder pressure, which was increased by about 9.8%-14.57%. However, it decreased the cylinder temperature, and shorten ignition delay (ID) and combustion duration (CD). In addition, the use of the pre-injection strategies could reduce the emissions of the engine pollution, in which the emission of NOx was reduced by about 46.43%-87.18%, and the emission of hydrocarbons (HC) was reduced by about 24.05%-38.03%. However, the brake specific fuel consumption (BSFC) increased. The optimal combination parameters of PT and PMR obtained by orthogonal test design were -45 degrees CA and 0.3. At this point, the peak cylinder pressure was 8.83 MPa, the BSFC was 304.46 g/(kW center dot h), and the NOx emission was 168.74 ppm. Therefore, this study could provide some theoretical foundations for the optimization of fuel injection strategy coupled with the oxygenated fuels combustion process.