Experimental investigation on combustion, noise, vibrations, performance and emissions characteristics of diesel/n-butanol blends driven genset engine

Several emerging economies, including India, use diesel widely to produce electric power. This is accomplished through millions of small or medium sized generators driven by diesel engines. These engine-alternator combinations, or gensets, are extremely noisy, generate vibrations, and pollute air. There is a pressing need to find alternatives to diesel for such applications. Diesel-alcohol blends (diesohols) could be such alternatives. However, not much effort has been made till so far to evaluate their noise, vibration, emissions, performance, and combustion characteristics. This work fills such a gap by comprehensively investigating the efficacy of four different diesel/n-butanol blends. For this, a single-cylinder 4-stroke naturally aspirated direct injection diesel genset engine was operated at a fixed rpm and at six different load conditions. Detailed measurements of combustion noise, exhaust noise, total noise from the engine, engine vibrations, emissions (NOx, HC, CO, and smoke), engine pressure, and fuel consumption were made. Data from these measurements were used to establish inter-relationships between engine's noise, vibration, emission, combustion and performance parameters. Linkages between these parameters, and key physical and chemical properties of test fuels were explored. Results show that noise and vibration characteristics of test diesohols are somewhat better especially at lesser loads. However, this trend reverses at higher loads. Analyses of results show strong correlation between combustion noise, rate of pressure rise, and vibration characteristics of test fuels. This work provides a detailed phenomenological explanation for such correlations in terms of fuel properties. Diesohols were also found to perform better for CO, NOx, and smoke emissions. However, the same may not be said for hydrocarbon emissions and engine efficiency particularly for diesohols with high n-butanol content. Finally, this work establishes that blends of n-butanol and diesel are viable alternatives for diesel for genset applications.