RSM-Based Investigation and Optimization of Ethanol Port Injection, EGR Rate, Engine Load, and Fuel Type on Combustion Noise and Vibration in a Diesel Engine

English (OpenAlex)

Noise and vibration caused by the operating principles and structural characteristics of diesel engines are critical in terms of passenger comfort and engine components' lifespan. The use of ethanol as a dual fuel in diesel engines and carbon nanotube (CNT) additives offers an innovative approach to optimizing noise and vibration levels by improving combustion characteristics. In this study, the effects of ethanol port injection rate, exhaust gas recirculation (EGR) rate, engine load, and nanotube-enhanced fuel types on the noise and vibration characteristics of a single-cylinder diesel engine were investigated. Experiments were conducted using different ethanol rates (10-30%), EGR rates (0-20%), and fuel types (neat diesel, diesel with 25-50 ppm SWCNT and MWCNT additives), and measurements of noise and vibration levels were performed using specialized sensors and data acquisition systems. Central composite design (CCD) was used to create the experimental matrix, while response surface methodology (RSM) was used for optimization. analysis of variance (ANOVA) showed that all input parameters significantly affected noise and vibration responses, with engine load emerging as the dominant factor. As a result of global optimization, the lowest noise (93.5 dBA) and vibration (88.9 m/s2) values were obtained at a 17.7% ethanol content, 20% EGR rate, and 50 ppm SWCNT-containing fuel coded SW50 under 0% load conditions. SWCNT-blended fuels demonstrated superior performance compared to neat diesel and MWCNT-blended fuels, particularly under low load conditions. The results indicate that moderate ethanol enrichment, appropriate EGR application, and CNT-blended fuels are effective strategies for reducing engine noise and vibration. The study provides a robust statistical basis for developing advanced combustion strategies to improve noise, vibration, and harshness (NVH) performance in compression-ignition engines.