Crude palm oil fuel for diesel-engines: Experimental and ANN simulation approaches T.F. Yusaf a, * , B.F. Yousif a , M.M. Elawad b a Faculty of Engineering and Surveying, University of Southern Queensland, Toowoomba 4350 QLD, Australia b Mechanical Engineering Department, Faculty of Engineering, University of Khartoum, Sudan article info Article history: Received 2 October 2010 Received in revised form 18 May 2011 Accepted 20 May 2011 Available online 21 June 2011 Keywords: Crude palm oil Diesel engine BSFC BP Exhaust-gas emissions abstract In the current work, the effect of using CPO (crude palm oil)eOD (ordinary diesel) blends as fuel on the performance of CI (compression ignition) engine is studied. Three different blends of CPOeOD (25%, 50% and 75%) were investigated using direct-injection, stationary diesel engine. The CPOeOD blends were preheated to about 60  C before the injection to reduce the viscosity of the blends. The experiments were conducted at variable engine speeds (1000 rpm through 3000 rpm) under fixed throttle opening. The results revealed that the CPOeOD exhibited higher torque and power output at engine speeds lower than 2000 rpm, while the BSFC (brake specific fuel consumption) was found to be higher than the OD at the same engine speeds. CPO enhanced the BSFC at higher engine speeds (above 2000 rpm). The CPOeOD blends exhibited lower emissions of NO x and higher emission of CO compared to the OD. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Fossil fuels are identified as the main source of energy for various industrial applications. However, fossil fuel reserves are rapidly diminishing, while the demand for energy worldwide is increasing. On the other hand, the damage to the environment through large quantities of green-house gases and pollutants encourages intensified research for alternative sources of energy, which is environment-friendly. Vegetable oils are found to be a potential source of energy that could substitute the fossil fuels [1e3]. From recent reported works, it has been found that vegetable oils have generally lower calorific values compare to ordinary diesel fuel, see Table 1 [4e6]. The combustion of vegetable fuels leads to a near balanced CO 2 cycle and a favorable reduction in green-house effects [4,7e12]. The high flash-point of vegetable fuels (about 198  C), as compared to liquefied fossil fuels, makes them safe to store and transport (Table 1) [4e6]. On the other hand, there is a limitation in using pure vegetable oils as fuels in internal combustion engines. The limitation is the formation of carbon deposit in the combustion chamber. This may lead to some problems such as the injector clocking and/or the valve sticking [8]. These problems are mainly occurred because of the high viscosity and the lower volatility of pure vegetable fuels compared to ordinary diesel fuel in reported works [2,3]. It has been found that the viscosity of crude palm oil (CPO) can be reduced by heating the oil in the fuel transport system. This tech- nique was adopted in the present work, and contributed to improve the combustion efficiency and the specific power, and reduce some of the exhaust gas emission components at different blendes CPOeOD ratios. Another attempt by Ref. [2] has been made to overcome the viscosity problems by using a direct-injection system and adding additives to the vegetable oil, the results showed good improvements [2]. As illustrated in Table 1 , the kinematic viscosity of ordinary diesel (OD) is 36 mm 2 /s, which is lower than the kinematic viscosity of crude palm oil (CPO) of 45 mm 2 /s. It is expected that when the CPO percentage increases, the kinematic viscosity of the blend increases as well. The Cetane rating of palm oil fuel was reported to be slightly lower than the OD, Table 1 [4e6]. Furthermore, the preheating technique was reported to be able to increase the thermal efficiency [4]. From the reported works in Refs. [5,9] biodiesel has a very high potential to replace the conventional fuel and enhance the engine performance. However, NO x concentration in the exhaust gas emission is considered to be one of the major disadvantages in using biodiesel fuels. In the present work, it was found that using CPO in the diesel engine can reduce NO x formation at certain engine operating conditions. This can be one of the main motiva- tions in reporting the current work. * Corresponding author. Tel./fax: þ61 7 4631 1373. E-mail address: yusaft@usq.edu.au (T.F. Yusaf). Contents lists available at ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy 0360-5442/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.energy.2011.05.032 Energy 36 (2011) 4871e4878