Optimisation of Karanja/Jatropha-Methanol emulsification variables and their engine evaluation Avinash Kumar Agarwal a, * , Vikas Katiyar b , Kushagra Singh a a Engine Research Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, India b Environmental Engineering and Management Program, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, India article info Article history: Received 6 July 2015 Received in revised form 14 March 2016 Accepted 29 April 2016 Keywords: Emulsified fuels Performance Emissions Methanol Jatropha Karanja abstract Vegetable oil based emulsified fuels have emerged as an attractive option for existing diesel engines. The issues such as higher viscosity and exhaust emissions such as oxides of nitrogen (NO X ), particulate matter (PM) are associated with straight vegetables oils (SVO), which can be potentially eliminated by making SVO emulsions, without worrying about PM-NO x trade-off. In this study, emulsions were prepared, where methanol was used as a dispersed phase and SVOs (Jatropha and Karanja) were used as contin- uous phase. A non-ionic commercial surfactant ‘Sorbitan monooleate’ also known as ‘Span ® 80’ was added and the mixture was stirred by a mechanical stirrer to produce emulsified fuel. Effect of several process variables such as surfactant concentration, stirrer speed and stirring duration on emulsion stability were optimised. The optimum surfactant concentration, stirrer speed, and stirring duration were determined for Methanol-Jatropha/Karanja emulsions. Emulsified fuels had important fuel properties comparable to baseline mineral diesel. These emulsions were blended with diesel in 1:3 proportions and evaluated in a single cylinder diesel engine for their performance and emissions characteristics. Per- formance and emission characteristics of emulsified blends followed a trend, which was related to methanol concentration in the dispersed phase of the emulsions. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Worldwide there is an increasing concern over combustion- generated pollutants such as particulate matter (PM), oxides of nitrogen (NO x ), carbon monoxide (CO) and total hydrocarbons (THC). This has forced the regulatory agencies worldwide to implement stringent emission regulations in different parts of the world to tackle the pollution at source. Diesel engines are widely used because of their high thermal efficiency, reliability, adapt- ability and cost effectiveness in long-term. However, they are one of the main source of pollutants such as PM and NO x in the environ- ment. It is difficult to comply with stringent emission norms for PM and NO x only by improving combustion chamber design and in- jection systems. It is accepted widely that clean combustion in diesel engines can be achieved by engine improvements, in addi- tion to fuel reformulation. Oil crisis in 1970 had forced many countries to explore using alternate fuels as a partial replacement of fossil fuels [1]. These alternate fuels should be renewable, sustainable, efficient, cost- effective and locally available in order to be commercially viable, environment friendly and acceptable. Biofuels, such as ethanol/ methanol, straight vegetable oils (SVO) and biodiesel are gaining prominence from energy security and environmental preservation point of view because these fuels can provide large-scale employ- ment in rural areas of developing countries since their processing can be done in rural areas itself, without the need for transporting them long distance. This therefore eliminates transportation cost for distribution [2]. In addition, large dependence of developing economies on imported fuel leads to significant economic stress on their foreign exchange reserves [3]. According to an estimate, India alone imported ~189 MMT crude oil during FY 2013e2014, valued at US$ 140 billion, which caused a huge burden on the exchequer [4]. Demand for crude oil is continuously rising every year. Each 1 US$ increase in crude oil price increases India's petroleum import bill by ~620 million US$/year [5]. In such a scenario, diesel fuel production from locally available resources is an attractive option in developing countries to fulfill demand for transportation fuels in future. Using vegetable oils and their derivatives is an effective option for reducing burden on imported petroleum fuels. India has * Corresponding author. E-mail address: akag@iitk.ac.in (A.K. Agarwal). Contents lists available at ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene http://dx.doi.org/10.1016/j.renene.2016.04.092 0960-1481/© 2016 Elsevier Ltd. All rights reserved. Renewable Energy 96 (2016) 433e441