694 J SCI IND RES VOL 70 AUGUST 2011 Journal of Scientific & Industrial Research Vol. 70, August 2011, pp. 694-698 *Author for correspondence Tel.: +91 11 26591260; Fax: +91 11 26591121 E-mail: lmdasgroup@gmail.com Comparative study of performance and emissions characteristics of a diesel engine fueled with jatropha and karanja biodiesel Lalit Prasad 1 , Subhalaxmi Pradhan 2 , C S Madankar 2 , L M Das 1 * and S N Naik 2 1 Centre for Energy Studies, 2 Centre for Rural Development and Technology, Indian Institute of Technology Delhi, New Delhi 110 016, India Received 04 May 2011; revised 14 June 2011; accepted 16 June 2011 This study presents extraction of oil by mechanical expeller and solvent extraction technique from jatropha and karanja seeds. Physico-chemical properties of extracted oil, jatropha oil methyl ester (JOME) and karanja oil methyl ester (KOME) were tested for their suitability in diesel engine. Mechanical extraction efficiency with expeller developed by IIT Delhi was found to be better (jatropha, 87%; karanja, 86%) as compared to traditional expeller (67-69%). Induction periods (oxidation stability) at 110°C were found to be: JOME, 1.76; and KOME, 2.24 h. Calorific value of JOME (38.65 MJ/kg) and KOME (40.75 MJ/kg) was comparatively lower to base diesel (44.50 MJ/kg). Comparative performance (brake thermal efficiency, brake specific fuel consumption) and emission (CO, THC, NO x and smoke opacity) characteristics were tested in 4.4 kW, single cylinder, compres- sion ignition engine with constant speed (1500 rpm). Keywords : Biodiesel, Esterification, Oxidation stability, Transesterification Introduction Biodiesel as an alternate diesel fuel has attracted considerable attention around the world due to its renewable, biodegradable, eco-friendly and non-toxic nature 1,2 . Different tree borne non-edible oil seeds (jatropha, karanja, mahua, simaruba, castor and neem) have been identified as a potential source for biodiesel production in India. Crude oil consumption has continued to rise @ 4.8% per annum since 2005 3 . A National Mission on Biodiesel identified Jatropha curcas as the most suitable tree-borne oilseeds 4 . Indian approach to biofuels is based solely on non-food feedstocks to be raised on degraded or wastelands, thus avoiding a possible conflict of fuel vs food security 5 . One of the major technical issues facing biodiesel is its susceptibility to oxidation upon exposure to oxygen in ambient air 6 .Stability of karanja oil methyl ester (KOME) has been improved by adding different antioxidants 7-9 [tert-butylated hydroxy toluene (BHT), tert-butylated hydroxyanisole (BHA), pyrogallol (PY), propyl galate (PrG) and tert-butyl hydroxyl quinone (TBHQ)]. Oxidation stability describes degradation tendency of biodiesel and is of great importance in the context of possible problems with engine parts. During degradation, main oxidation products (peroxides and hydroperoxides) form shorter-chain compounds such as low molecular weight acids, aldehydes, ketones and alcohols 10-11 . This study presents oil extraction from jatropha and karanja seeds by solvent extraction and mechanical expression designed and fabricated by IIT Delhi 12 , preparation of biodiesel [jatropha oil methyl ester (JOME) and KOME] and physico-chemical analysis of oil as well as methyl ester, besides comparative performance and emission study of biodiesel blends (B15) of JOME and KOME and diesel in single cylinder compression ignition (CI) engine. Experimental Section Oil Extraction and Characterisation Jatropha and karanja seeds were collected from IIT campus, New Delhi, India. Seeds were cleaned manually to remove all foreign materials, sun dried and then dried in hot air oven till free from moisture. Seeds were decorticated manually to obtain kernel. For oil content determination 13 , grounded samples were extracted by soxhlet apparatus using petroleum ether (b.p. 60-80°C).