Performance of diesel engine with biodiesel at varying compression ratio and ignition timing H. Raheman * , S.V. Ghadge Agricultural and Food Engineering Department, Indian Institute of Technology, Kharagpur 721302, India article info Article history: Received 29 June 2007 Received in revised form 6 March 2008 Accepted 7 March 2008 Available online 3 April 2008 Keywords: Mahua biodiesel Engine performance Varying compression ratio Injection timing abstract The performance of Ricardo E6 engine using biodiesel obtained from mahua oil (B100) and its blend with high speed diesel (HSD) at varying compression ratio (CR), injection timing (IT) and engine loading (L) has been presented in this paper. The brake specific fuel consumption (BSFC) and exhaust gas temperature (EGT) increased, whereas brake thermal efficiency (BTE) decreased with increase in the proportion of bio- diesel in the blends at all compression ratios (18:1–20:1) and injection timings (35–45° before TDC) tested. However, a reverse trend for these parameters was observed with increase in the CR and advancement of IT. The BSFC of B100 and its blends with high speed diesel reduced, whereas BTE and EGT increased with the increase in L for the range of CR and IT tested. The differences of BTEs between HSD and B100 were also not statistically significant at engine settings of ‘CR20IT40’ and ‘CR20IT45’. Thus, even B100 could be used on the Ricardo engine at these settings without affecting the performance obtained using HSD. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction The growing concern on environmental pollution caused by the extensive use of conventional fossil fuels has led to search for more environment friendly and renewable fuels. Among various options investigated for diesel fuel, biodiesel has been reported to be one of the strong contenders for reductions in exhaust emissions. Several countries including India have already begun substituting the con- ventional diesel by a certain amount of biodiesel. It was reported that engine parameters such as CR, IT and L were found to have sig- nificant effect on performance and emissions of diesel engine when run with biodiesel and its blend with diesel [1–3]. Hence, a study was undertaken at IIT Kharagpur, India to gather information on behavior of diesel engine when operated with biodiesel and its blend with diesel at varying L, CR and IT. 2. Experiments Constant speed (1500 rpm) short term engine performance (STEP) tests were conducted in a 9 kW single cylinder, naturally aspirated, four stroke, water cooled Ricardo E6 engine at varying compression ratio (18:1–20:1), injection timing (35–45° before TDC) and load (0%, 25%, 50%, 75% and 100% load corresponding to load at maximum power) using biodiesel (B100) and its blends with high speed diesel (B20, B40, B60, B80) to determine how each fuel would perform under identical engine and load conditions. 2.1. Experimental set-up The major specifications of the Ricardo engine are presented in Table 1. The CR of this engine was varied from 18:1 to 20:1 by raising or lowering the cylinder relative to the crankshaft by means of a worm wheel. The movement of the cylinder was measured by means of a micrometer fitted on the cylinder. The IT of this engine was varied with the help of a hand control lever provided with injec- tion pump assembly. The timing could be varied between 30° and 45° before TDC while the engine was running. With the comet type cylinder head, a CAV type BDN12SD12 injector was provided. The engine was coupled to a swinging field electric dynamom- eter for application of variable load and it was applied by closing the load switch with the rheostats in the weak field position. It was increased by strengthening the field by increasing the amper- age and was measured as a torque (Nm) through a microprocessor based digital indicator. The maximum load, which the engine could take at 1500 rpm was found to be 24 Nm. This was taken as 100% load for the present investigation. Accordingly, intermediate loads were calculated as 0, 6, 12 and 18 Nm to represent 0%, 25%, 50% and 75% loading conditions. 2.2. Biodiesel The biodiesel obtained from mahua oil and its blend with diesel were considered in this study. The various fuel properties of mahua biodiesel (B100) and its blends with high speed diesel (HSD) were determined as per the ASTM standards and procedures and are summarized in Table 2. It can be seen from this table that the fuel 0016-2361/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.fuel.2008.03.006 * Corresponding author. Tel.: +91 3222 283160; fax: +91 3222 282244. E-mail address: hifjur@agfe.iitkgp.ernet.in (H. Raheman). Fuel 87 (2008) 2659–2666 Contents lists available at ScienceDirect Fuel journal homepage: www.fuelfirst.com