Abstract As a substitute to petroleum-derived diesel, biodiesel has high potential as a renewable and environment friendly energy source。 For petroleum importing countries the choice of feedstock for biodiesel production within the geo- graphical region is a major influential factor。 Crude rice bran oil is found to be good and viable feedstock for biodiesel production。 A two step esterification is carried out for higher free fatty acid crude rice bran oil。 Blends of 10, 20 and 40 % by vol。 crude rice bran biodiesel are tested in a variable compression ratio diesel engine at compression ratio 15, 16, 17 and 18。 Engine performance and exhaust emission parameters are examined。 Cylinder pressure-crank angle variation is also plotted。 The increase in compression ratio from 15 to 18 resulted in 18。6 % decrease in brake specific。84467

fuel consumption and 14。66 % increase in brake thermal efficiency on an average。 Cylinder pressure increases by 15 % when compression ratio is increased。 Carbon monoxide emission decreased by 22。27 %, hydrocarbon decreased by

38。4 %, carbon dioxide increased by 17。43 % and oxides of nitrogen as NOx emission increased by 22。76 % on an aver- age when compression ratio is increased from 15 to 18。 The blends of crude rice bran biodiesel show better results than diesel with increase in compression ratio。

Keywords: Crude rice bran biodiesel, Variable compression ratio, Engine performance, Cylinder pressure, Exhaust Background

Fossil fuels are the major source of energy worldwide。 The cheaper cost of diesel as an automotive fuel com- pared to gasoline has received increased attention, which further has resulted in the increase of on road mid-size diesel vehicles (Sedan and Hatchback class)。 This increase in number of vehicles on road along with uncontrolled emissions from motor vehicles has majorly affected the concentration of air pollution, raising serious environ- mental issues。

The leading cause of death worldwide is air pollution according to WorldHealth Organisation (WHO)。The

2014 version of the Ambient Air Pollution (AAP) (AAP 2014) in cities database released by WHO ranks New Delhi (National capital of India) as the most polluted city in the world。 New Delhi has the worst air conditions in the world measuring the concentration of air pollution at 153 micrograms per cubic meter (µg/m3) of air, which is far much greater than normally considered safe air (31– 60 µg/m3)。 Also half of the top 20 most polluted cities in world are in India only。 With the continuous increase in energy demands, concentration of air pollution and lim- ited availability of fossil fuels, the need for alternative environmental friendly renewable sources of energy have comeintofocus。Beingbiodegradable,non-toxicand

  environmental friendly in nature, biodiesel has received

*Correspondence: mohitvasudeva@hotmail。com

1 Mechanical Engineering Department, Baddi University of Emerging Sciences and Technology, Baddi, India

Full list of author information is available at the end of the article

increased attention as an alternative renewable source。 Oils and fats are the major sources of biodiesel produc- tion(BalatandBalat2008;Schuchardtaetal。 1998)。

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Vegetable oils can be introduced in engine directly, how- ever due to high viscosity it results in poor atomization, injection and combustion problems。 In order to reduce viscosity of the vegetable oils, trans-esterification is car- ried out (Fukuda et al。 2001; Ma and Hanna 1999; Gerpen 2005; Leung et al。 2010)。