Numerical optimization of natural gas composition effects on dual-fuel diesel engine performance and emissions

In this paper a three-dimensional modeling of a Natural Gas (NG)-diesel dual fuel engine with the effect of different NG composition injection has been discussed. In order to do this, four NG composition produced by Pars, Ghasho, Kangan and Khangiran refineries have been considered. First, Computation Fluid Dynamics (CFD) model has been validated with experimental data. During optimization, objective functions include minimum indicated specific fuel consumption (ISFC), indicated torque (IT) and break mean effective pressure BMEP have been considered by TOPSIS method. Engine performance parameters and pollutant emission has been discussed in this paper. Finally, best NG composition refinery has been obtained based on numerical and optimization analysis. The highest and lowest values of pressure is related to combination of Khangiran and Ghasho refineries with 12.8 and 11.4 MPa, respectively. Also, with an 8 % reduction of methane in composition, maximum incylinder pressure decreases by 4 %. Therefore, Khangiran gas has a higher temperature than other gas compounds due to more methane species. The maximum temperature for Ghasho Refinery occurs at ATDC and near +1 degrees CA, while for other gas compositions occur at BTDC and near -2 degrees CA. The gas composition in Khangiran, Kangan, and Pars shows that the maximum combustion temperature depends on the amount of CH4. Optimal conditions during engine performance have been obtained related Kangan refinery and Khangiran and Ghasho refineries are listed second and third gas composition.