Effect of methanol concentration on combustion and vibro-acoustic behaviour of a single-cylinder diesel engine fuelled with waste fried oil biodiesel-methanol-diesel ternary fuel blends at lower compression ratio

Many studies explored the performance, emission, and combustion characteristics of the ternary fuel blends; however, the noise and vibration levels of the engine fueled with ternary fuel blends are not much explored. So, in this study, the influence of methanol concentration in ternary fuel blends (waste fried oil biodiesel (B)-diesel (D)-methanol (M)) on combustion and vibro-acoustic behavior is explored in a single-cylinder diesel engine. Three ternary blends were prepared by varying biodiesel and methanol ratios. The experiments are carried out by varying the engine load at a lower compression ratio of 17:1. Vibro-acoustic measurements were taken using a triaxial accelerometer on the cylinder head and two microphones. Ternary blends with 10% and 30% methanol increased cylinder pressure by 3.46% and 3.38% at peak load, respectively, compared to diesel. At mid-load, 10% and 20% methanol blends exhibited 4.1% and 1.23% higher cylinder pressure. Ternary blends with higher methanol concentrations significantly increased the rate of pressure rise. B20M30D50, B30M20D50, and B40M10D50 showed RoPR increases of 5.81%, 13.103%, and 5.66%, respectively. Methanol concentrations above 10% increased acceleration amplitudes across all accelerometer directions. Higher noise pressure levels were observed near the intake and exhaust manifolds, likely due to their proximity to fluid-induced noise sources.