Influence on the effect of zinc oxide and titanium dioxide nanoparticles as an additive with Calophyllum inophyllum methyl ester in a CI engine K. Nanthagopal, B. Ashok ⇑ , A. Tamilarasu, Ajith Johny, Aravind Mohan School of Mechanical Engineering, VIT University, Vellore 632014, India article info Article history: Received 30 January 2017 Received in revised form 24 April 2017 Accepted 9 May 2017 Keywords: Biodiesel Calophyllum inophyllum Nanoparticle Nano additive Titanium dioxide Zinc oxide abstract The present experimental work aims at investigating the effect of zinc oxide and titanium dioxide nanoparticles addition in Calophyllum inophyllum biodiesel in twin cylinder water cooled direct injection four stroke diesel engine. The nanofluids have been prepared from 50 ppm and 100 ppm concentrations of titanium dioxide and zinc oxide with distilled water through ulrasonication process. Four different Calophyllum inophyllum nano emulsions have been prepared with the proportions of 93% of Calophyllum inophyllum biodiesel, 5% of nanofluids of zinc oxide and titanium dioxide and 2% of span 80 using mechanical stirrer. The compression ignition engine characteristics were examined with all four Calophyllum inophyllum nano emulsions and the results were compared with conventional diesel and pure Calophyllum inophyllum biodiesel under various engine loads. The diesel engine operation with CIME nano emulsions improves brake thermal efficiency by 5–17% compared to pure CIME fuel at max- imum brake power due to large surface to volume ratio of nanoparticles which exhibit rapid evaporation and better atomization. Further, the CO and HC emissions were reduced drastically for CIME nano emul- sions compared to pure biodiesel and conventional diesel fuel. The NOx emission was lower than pure Calophyllum inophyllum biodiesel for all CIME nano emulsions but slightly higher than conventional diesel fuel. The smoke emission of diesel engine was reduced drastically for all CIME nano emulsions compared to both pure biodiesel and diesel fuels at all engine loads. Combustion characteristics of in cylinder gas pressure and heat release rate were increased by the addition of nano particles with pure Calophyllum inophyllum at all engine loads. Finally, it can be observed that the doping of nano particles with biodiesel has a very good effect on performance characteristics with notable improvement in performances and minimum emissions. Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction Increasing energy demands, depletion of fossil fuels and strin- gent emission norms urged the scientific community to search for alternate fuels such as biodiesel for diesel engine applications which bridge the gap between demand and energy source for auto- motive sector [1,2]. Moreover from an economic point of view, India spends around 80,000 Cr INR annually for purchase of fuel alone. A shift towards indigenously produced biodiesel fuels helps to reduce the expenditure and this can boost up the country econ- omy [3]. Biodiesels are readily available, bio degradable, portable, nontoxic and renewable in nature. It can be extracted from a vari- ety of natural feedstock sources and globally around 350 crops are recognized as the possible feedstock for biodiesel production. Numerous types of seeds from the plants like pongamia, jatropha, mahua, castor, etc are utilized to produce biodiesel which are non-edible in nature. These non-edible oil plants are considered as second generation feedstock due to their economically cheap and easily cultivated in many parts of the world [4,5]. Transester- ification is the most feasible and viable technique in which all non- edible oil can be brings down to diesel like properties. Calophyllum inophyllum seeds are one of the non-edible feedstock for biodiesel http://dx.doi.org/10.1016/j.enconman.2017.05.021 0196-8904/Ó 2017 Elsevier Ltd. All rights reserved. Abbreviations: BTDC, before top dead center; BSFC, brake specific fuel con- sumption; BSEC, brake specific energy consumption; BTE, brake thermal efficiency; BMEP, brake mean effective pressure; CIME, Calophyllum inophyllum methyl ester; CIME-T50, 93% Calophyllum inophyllum methyl ester + 2% span-80+ 5% nanofluid of 50 ppm TiO 2 ; CIME-T100, 93% Calophyllum inophyllum methyl ester + 2% span-80+ 5% nanofluid of 100 ppm TiO 2 ; CIME-Z50, 93% Calophyllum inophyllum methyl ester + 2% span-80+ 5% nanofluid of 50 ppm ZnO; CIME-Z100, 93% Calophyllum inophyllum methyl ester + 2% span-80+ 5% nanofluid of 100 ppm ZnO; DI, direct injection; FFA, free fatty acid; BSHC, brake specific unburned hydrocarbon; BSNOx, brake specific oxides of nitrogen emission; BSCO, brake specific carbon monoxide; CIME100, 100% Calophyllum inophyllum methyl ester; ppm, parts per million; g/ kWh, grams per kilowatt hour; EGR, exhaust gas recirculation; IT, injection timing; CA, crank angle. ⇑ Corresponding author. E-mail address: ashokmts@gmail.com (B. Ashok). Energy Conversion and Management 146 (2017) 8–19 Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman