IOSR Journal of Engineering (IOSRJEN) www.iosrjen.org ISSN (e): 2250-3021, ISSN (p): 2278-8719 Vol. 04, Issue 05 (May. 2014), ||V3|| PP 36-41 International organization of Scientific Research 36 | P a g e Performance Characteristics of a Gasohol Fueled S.I Engine. Laminu S. Kuburi, David O. Obada, Ibraheem A. Samotu, Chike V. Chira Obinna A. Osuchukwu and M. Jeremiah. Department of Mechanical Engineering, Ahmadu Bello University, Zaria, Nigeria. Abstract: - Ethanol is a renewable fuel which has the added advantage of improving performance in typically knock-limited operating regions due to the higher octane rating of the fuel. Ethanol was synthesized from groundnut seeds using fermentation method. An experiment was then designed to run a gasoline engine. In this work, the effect of ethanol addition to gasoline on the performance characteristics of a spark ignition engine at various speeds was established. Gasoline was blended with 20 – 80% of the extracted ethanol in an interval of 20%. Results of the engine test indicated that blending ethanol in a proportion of 40% with gasoline can be used as a supplementary fuel in modern spark ignition engines as it is expected to achieve optimum performance on the engine. Keywords: - Ethanol, Gasoline, performance, Spark ignition engine. I. INTRODUCTION While ethanol is an attractive option for offsetting dependence on petroleum based gasoline, the differences in fuel properties between gasoline and ethanol can significantly alter engine performance [1], [2], [3]. Due to the different molecular structure of ethanol, the stoichiometric air-fuel ratio of ethanol is substantially different than gasoline and the air and fuel controllers must target different values for ethanol blends. Ethanol also has a different laminar flame speed than gasoline; therefore, the rate at which flames propagate during combustion will differ depending on the fuel ethanol content and combustion phasing will be directly affected. In addition, as a result of its higher octane rating, ethanol has a higher resistance to knock than gasoline. Ethanol fuel is ethanol (ethyl alcohol), the same type of alcohol found in alcoholic beverages. It can be used mainly as a biofuel alternative to gasoline, and is widely used by flex-fuel light vehicles in Brazil, and as oxygenate to gasoline in the United States. Together, both countries were responsible for 89% of the world’s ethanol production in 2008 [4]. As noted by Blume [5], the following are the key reasons for which ethanol is attractive as a substitute to gasoline: Ethanol is 98% pollution free; biodegradable; renewable; there is no carbon left when ethanol burns in cars; ethanol does not cause climate change; and all the by-products in the production of ethanol are edible and nontoxic, providing a very good source for animal feedstock. Methanol has also been proposed as a fuel for internal combustion and other engines mainly in combination with gasoline. Historically, methanol was first produced from pyrolysis of wood. Presently, methanol is usually produced using methane as a raw material. Both methanol and ethanol burn at lower temperatures than gasoline, and both are less volatile, making engine starting in cold weather more difficult. Using methanol as a fuel in spark ignition engines can offer an increased thermal efficiency and increased power output due to its high octane rating (114) and high heat of vaporization. However, its low energy content of 19.7 MJ/kg and stoichiometric air fuel ratio of 6.42:1 mean that fuel consumption will be higher than hydrocarbon fuels [6]. Ethanol (CH 3 CH 2 OH) is more reactive than hydrocarbon fuels, such as gasoline. Since it is an alcohol, its molecular structure shows a polar fraction due to the hydroxyl radical and a non polar fraction in its carbon chain. That explains why ethanol can be dissolved in both gasoline (non polar) and in water (polar). Due to its short carbon chain, the properties of ethanol polar fraction overcome the non polar properties. The formation of hydrogen bridges in ethanol molecule results in higher boiling temperature in comparison to that of gasoline. Ethanol is less toxic than methanol – another alcohol used as fuel. The simple structure of ethanol molecule makes it suitable for spark ignition internal combustion engines operation. The high octane number of ethanol allows for higher compression ratios in comparison to gasoline fuelled engines [7] .In Brazil, ethanol is produced from sugar-cane, a renewable energy source. Sugar cane molasses contains about 40% sucrose, which hydrolysis by an enzyme called invertase produces glucose or fructose. The enzyme is elaborated by brewer’s yeast. Ethanol is formed by glucose (C 6 H 12 O 6 ) fermentation in the presence of another enzyme called zymase. This is shown in the equations below; C 12 H 22 O 11 + H 2 O xC 6 H 12 O 6 + (2-x) C 6 H 12 O 6 0 ≤ x ≤ 1 ………. (1) C 6 H 12 O 6 2C 2 H 5 OH + 2CO 2 ……………………………….... (2)