Assessing the impact of Ricinus communis L. biodiesel–butanol blends, nano-additives and fuel injection timing on CI engine vibration and noise levels

The aim of this study is to experimentally investigate the vibro-acoustic behavior of a single-cylinder compression ignition engine fuelled with ternary blends of Ricinus communis L. biodiesel, n-butanol and graphene oxide nanoparticles with special emphasis on the effect of injection timing. Experiments were performed at injection timings of 21°, 23° and 25° bTDC. The vibration velocity of the engine was measured by Laser Doppler Vibrometry and the noise characteristics were evaluated based on sound pressure level measurements. The vibro-acoustic responses of the fuel blends studied were comparatively evaluated at different injection timings. With the injection timing advanced, the diesel vibration velocity was reduced from 0.843 m/s to 0.467 m/s. Among the blends of nanoparticles, the D65B20nB15 + 75 ppm NPs blend produced a minimum vibration velocity of 0.156 m/s at 25° bTDC, which is 81.5% lower than that of diesel at 21° bTDC. The D70B20nB15 blend showed vibration reductions of 22.0%, 19.7% and 66.6% at 21°, 23° and 25° bTDC respectively. The sound pressure levels also decreased from 70.37 dB to 58.33 dB with advanced injection timing. The minimum RMS noise of 54.20 dB was achieved for D65B20nB15 + 75 ppm NPs at 25° bTDC. The results show that the fuel composition combined with the optimization of the injection timing can have a significant influence on the vibration and noise characteristics of the engine. Of the conditions tested, the D65B20nB15 + 75 ppm NPs at 25° bTDC provided the best overall vibro-acoustic response, suggesting it can be used to reduce engine vibration and noise under the experimental conditions studied.