Effects of air–fuel ratio on combustion performance enhancement and emission reduction of the methanol–diesel dual‐fuel engine

Abstract GT‐Power software was employed to model a methanol–diesel dual‐fuel engine operating at 1800 rpm for investigating the effects of the methanol air–fuel ratio (AFRm) in the intake port on engine combustion and emission performance. Eight AFRm values were selected for analysis: 15, 20, 25, 30, 35, 40, 45, and 50. Torque was used as the output signal to manage diesel injection mass by the controller. Research findings indicate that by maintaining constant engine torque and leveraging the complementary energy release of methanol and diesel fuel, fluctuations in brake power and efficiency caused by variations in AFRm remain below 2%. Increasing AFRm alters the composition of the methanol–air–diesel mixture, resulting in higher trapped AFR and induced AFR within the cylinder. The increased density of the combustion mixture elevates cylinder pressure and heat release rate, leading to higher temperatures throughout the system, particularly in the cylinder. A combination of elevated temperatures, increased oxygen content, and greater diesel injection results in 52.29% and 10.59% increases in NO x and CO 2 emissions, along with 6.51% and 15.87% decreases in CO and HC emissions. Second‐order regression equations were established for cylinder peak pressure, brake efficiency, BFSC, NO x , CO, CO 2 , and HC to demonstrate the influence of AFRm on these parameters visually. Confirmation test results indicate that the errors between simulated values and predicted values from the fitting curves remain within 1%. Due to the inherent limitations of one‐dimensional simulation and simplified chemical reaction mechanisms in GT‐Power, the predicted results may deviate from actual engine behaviour.