Prediction and Comparison of the Effect of N-butanol and Ethanol Addition to the Biodiesel-diesel Fuel Mixture on the Performance and Emissions Characteristics of a Diesel Engine

The main objective of this research is to study the effects of n-butanol and ethanol addition to the biodiesel-diesel fuel mixture on the performance and emission characteristics of a CI engine. The experimental tests were performed on a diesel engine. The RSM (Response Surface Methodology) method was used to develop mathematical models based on experimental data. According to the results, the addition of butanol and ethanol to the fuel mixture generally reduces the brake power and torque up to 16%.  However, with a further increase in biodiesel percentage with the addition of ethanol and butanol to the fuel mixture, the power and torque were improved slightly. Also, the addition of alcohols to the fuel mixture increases the BSFC by 5 to 9%. On the other hand, the addition of ethanol and n-butanol along with increasing the percentage of biodiesel in the fuel mixture could improve the BSFC, especially at higher RPMs. Comparing fuel mixtures containing ethanol and n-butanol, it was observed that the BSFC values in the case of using normal butanol are less than ethanol. According to the results, with the addition of ethanol and n-butanol, the carbon monoxide emission increases by 7 to 12%. However, it was improved in higher RPMs. The results also showed that ethanol-containing mixtures emitted more CO than that n-butanol-containing mixtures. According to the results by the addition of ethanol and n-butanol to the diesel-biodiesel fuel blends, the emission of nitrogen oxides is reduced by an average of 11% compared to the diesel-biodiesel mixture. However, the addition of ethanol to the fuel blends produces more NOx than that of n-butanol, especially at high engine speeds.