Impact of alcoholegasoline fuel blends on the exhaust emission of an SI engine Mustafa Canakci a, b , Ahmet Necati Ozsezen a, b, * , Ertan Alptekin a, b , Muharrem Eyidogan c a Department of Automotive Engineering, Kocaeli University, 41380 Izmit, Turkey b Alternative Fuels R&D Center, Kocaeli University, 41275 Izmit, Turkey c Automotive Technology Program, Vocational School, Karabuk University, 78050 Karabuk, Turkey article info Article history: Received 9 February 2012 Accepted 29 September 2012 Available online Keywords: Gasoline Ethanol Methanol SI engine Emissions abstract In this study, the effect of ethanolegasoline and methanolegasoline blends on the engine performance and combustion characteristics has been investigated experimentally. In the experiments, a vehicle having a four-cylinder, four-stroke, multi-point injection system SI engine was used. The tests were performed on a chassis dynamometer while running the vehicle at two different vehicle speeds (80 km/h and 100 km/h), and four different wheel powers (5, 10, 15, and 20 kW). The measured emission values with the use of E5, E10, M5, and M10 have been compared to those of pure gasoline. The experimental results revealed that when the test engine was fueled with ethanolegasoline or methanolegasoline blends, CO, CO 2 , unburned HC and NO x emissions decreased for all wheel powers at the speed of 80 km/h. However, when the vehicle speed was changed to100 km/h, more complex trends occurred in the exhaust emissions for the fuel blends, especially for the wheel power of 15 kW. It was also seen that the airefuel equivalence ratio increased with the increase of ethanol and methanol percentages in fuel blends when compared to pure gasoline case. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Energy diversity is a vital factor for economic growth and environmental protection. Building a strong base of energy resources is necessary for concern the efforts which are made to search a potential alternate. Both ethanol and methanol can be produced from various biomass resources. It should be noted that methanol can be only produced from natural gas due to economic reasons [1e3]. Ethanol and methanol have low cetane number which may lead insufficient self-ignition quality for direct use of these alcohols in unmodified diesel engines. The key property of ethanol and methanol is their high octane number. The addition of ethanol or methanol to gasoline raises the octane value of gasoline and reduces engine knock, without affecting the efficiency of the catalytic converter [4]. Indeed, when Henry Ford designed his first automobile (Model T), it was built to run on both gasoline and pure ethanol [5]. In the past, ethanol had not been used widely due to its insufficient production and high production cost. But, nowadays, increasing global concern due to air pollution caused by internal combustion engines has generated much interest on the environ- mental friendly alternative fuels. So far, experimental studies [6e9] have been claimed that the ethanol or methanol blended fuels reduce exhaust emissions compared to gasoline fueled engine. Generally, in these studies, the reductions in the exhaust emissions have been associated with the oxygen content in ethanol and methanol. It is well-known that the physical and chemical properties of ethanol or methanol are completely different from those of gasoline. Especially, their energy contents are lower than that of gasoline, both on mass and volume basis. This property shows that the engine will need more amount fuel when it is fueled with ethanol or methanol blends to produce the same power output in a gasoline-fueled engine. This case will change airefuel ratio in the cylinder and exhaust emission levels. One of the most important properties of methanol or ethanol is the oxygenated atoms in their molecular compounds which provide significant reduction in the CO and HC emissions, but it may be adversely affect NO x emissions. Methanol has a heat of vaporization that is about 3 times higher than gasoline; ethanol has higher heat of vaporization about 2.5 times (see Table 1). It can be considered that the mixture temperature will be influenced because of the cooling effect from the vaporization of ethanol or methanol, Abbreviations: bsfc, brake specific fuel consumption; CO, carbon monoxide; CO 2 , carbon dioxide; E5, 5% ethanol þ 95% gasoline (vol%); E10, 10% ethanol þ 90% gasoline (vol%); HC, hydrocarbons; M5, 5% methanol þ 95% gasoline (vol%); M10, 10% methanol þ 90% gasoline (vol%); NO x , nitrogen oxides; SAE, Society of Auto- motive Engineers. * Corresponding author. Department of Automotive Engineering, Kocaeli University, 41380 Izmit, Turkey. Tel.: þ90 262 3032288; fax: þ90 262 3032203. E-mail address: nozsezen@kocaeli.edu.tr (A.N. Ozsezen). Contents lists available at SciVerse ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene 0960-1481/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.renene.2012.09.062 Renewable Energy 52 (2013) 111e117