Effect of next generation higher alcohols and Calophyllum inophyllum methyl ester blends in diesel engine

Abstract

Biodiesel can serve as potential alternate fuels in compression ignition engine as it leads to an effective reduction in consumption of fossil fuels. Moreover, it has been observed that biodiesel has the potential to reduce the exhaust emissions as well as their usage is sustainable in nature. However, the lower calorific value of biodiesel coupled with higher oxygen content leads to a poor performance and higher oxides of nitrogen emissions when compared to diesel fuel. Hence, in the current study, the effect of introducing higher alcohols as a blend with Calophyllum inophyllum biodiesel in order to improve the performance and reduce the oxides of nitrogen emissions. Two different higher alcohols namely n-pentanol and n-octanol are blended with biodiesel in the proportion of 10%, 20% and 30% by volume in order to evaluate the performance, emission and combustion characteristics. The blending of higher alcohols with biodiesel reduces the auto ignition quality and density of the blends. Meanwhile, the increase in the concentration of n-pentanol with biodiesel reduces the calorific value and kinematic viscosity, whereas for n-octanol the results are reversed. The fuel samples are tested in a single cylinder, constant speed engine at different loads and the results are compared with diesel and pure biodiesel. The experimental study revealed that brake thermal efficiency is 8.9% and 3.6% is higher for B70O30 (70% of biodiesel and 30% of n-octanol) and B90P10 (90% of biodiesel and 10% of n-pentanol) compare to pure Calophyllum inophyllum biodiesel. It is observed that the blending of higher alcohols with biodiesel decreases the hydrocarbon emissions 8–22% and increase the carbon monoxide emission by 16–50%. Oxides of nitrogen emission are reduced significantly by 4.1% and 6.8% for B90P10 and B90O10 respectively at full engine load condition. On the other hand, the smoke emission increases from 21 to 35% for higher alcohols addition with biodiesel. Furthermore, the combustion characteristics better for higher alcohol blends due to their higher calorific value. In general, the blending of higher alcohol with biodiesel can overcome many shortcomings of pure Calophyllum inophyllum biodiesel for diesel engine applications.