Effect of next generation higher alcohols and Calophyllum inophyllum methyl ester blends in diesel engine K. Nanthagopal a , B. Ashok a, * , B. Saravanan b , Shane Mathew Korah a , Snehith Chandra a a School of Mechanical Engineering, VIT University, Vellore 632014, India b Indian Institute of Technology Hyderabad, India article info Article history: Received 26 July 2017 Received in revised form 16 November 2017 Accepted 21 January 2018 Keywords: Calophyllum inophyllum Biodiesel Methyl ester Higher alcohol n-pentanol n-octanol 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 in- crease in the concentration of n-pentanol with biodiesel reduces the calorific value and kinematic vis- cosity, 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 8e22% and increase the carbon monoxide emission by 16e50%. 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. © 2018 Elsevier Ltd. All rights reserved. 1. Introduction Fossil fuel depletion and stringent emission norms are the alarming factors that lead to a search for an alternate renewable energy source in the diesel engine applications. Diesel engines are considered to be a vital power source in the field of automotive, commercial, agriculture and construction sectors due to its high torque capability, durability and high-efficiency characteristics. However, the exhaust emissions from diesel engine such as NOx, smoke are higher than its counterpart and this could affect the human health and the environment in a serious manner (Rahman et al., 2014). Similarly, the usage of diesel engine power source keeps on increasing which leads to increase the atmospheric pollution and weakens the fossil fuel resources. To overcome the limitation of fossil fuel reserves, uncertainty in the oil price, global warming issues, toxic pollutants and problem in finding the oil suppliers are the factors that motivate various nations to derive an alternate energy source in the power sectors. Such kind of alternate energy source must be affordable, renewable in nature, availability and provides almost clean operation in diesel engines. In recent years, alternative fuels have shown a potential energy source due to its sustainable methods of production from various biological sources and the properties of the fuels is suitable for diesel engine * Corresponding author. E-mail address: ashokmts@gmail.com (B. Ashok). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro https://doi.org/10.1016/j.jclepro.2018.01.167 0959-6526/© 2018 Elsevier Ltd. All rights reserved. Journal of Cleaner Production 180 (2018) 50e63