The Effect of Gasoline-Bioethanol Blends to The Value of Fuel’s Octane Number

. A fuel gasoline engine classified based is octane number, test for octane number using CFR engine with RON (Research Octane Number) ASTM D 2699 and MON (Motor Octane Number) ASTM D 2700. Bioethanol can booster octane number if blended to gasoline. A fuel to a higher octane can be run at a higher compression ratio without causing detonation or knocking engine. Compression is directly related to thermodynamic efficiency but to blended bioethanol can decrease the heating value of the fuel. The design engine on the market had compression ratio specified and needed octane number minimum specified. The experimental using CFR engine and using fuel gasoline in the market with blended bioethanol start from 5% -20% and analysis the relationship octane number after blended bioethanol with value compression ratio gasoline engine at the market. The objective of this research was the effect of blended bioethanol of varying gasoline forward octane number. The effect of blended bioethanol of gasoline between 5%-20% could increase to 11% of gasoline octane 88, 2% of gasoline octane 98.


Introduction
Bioethanol can booster octane number if blended to gasoline. A fuel to a higher octane can be run at a higher compression ratio without causing detonation or knocking engine. Compression is directly related to thermodynamic efficiency but to blended bioethanol can decrease the heating value of the fuel. The design engine on the market had compression ratio specified and needed octane number minimum specified. The development technology engine for vehicle and motorcycle heading towards increasing compression ratio (CR) for optimum performance and improved engine thermal efficiency SI engine. The blended ethanol can reduce of engine knocking tendency [1][2][3].
The effectiveness increasing octane number with blended bioethanol to vary gasoline would to determine percentage bioethanol blend. As a biofuel, bioethanol can be used as a fuel substitution for gasoline. Bioethanol is a natural product and manufactured by the fermentation of plants containing sugar and starch. Characteristic physical and chemical of bioethanol near to gasoline. Using bioethanol-gasoline blended fuel can ease off the air pollution [4]. Increase ethanol content can increase the octane number, but decrease heating value [5]. Octane number is important parameter test for an effect to combustion, to decrease the octane number of combustion SI Engine can occur knocking. Two methods for measure octane number with research octane number and motor octane number of CFR engine [6,8]. The experimental test was using gasoline varying with octane number 88, 92, 98, and 5%, 10%, 15%, 20% bioethanol blends from the market in Indonesia.
Hence, the current work aims at presenting the result on the effect of different percentages of bioethanol blends with 3 types of gasoline fuel on the value of fuel's octane number that would be useful for preventing knocking on the engine.

Materials and Methods
This experiments used fuels of bioethanol and three kind gasoline from the market in Indonesia. At the heart of the CFR engine lies the variable compression cylinder and sleeve assembly by which the knock characteristics of unknown fuels can be determined. Varying the compression ratio by manipulating the cylinder height during engine operation produces various levels of knock intensity, making it possible to compare unknown fuels to reference fuels with known octane values. Cylinder height is correlated to a compression ratio which can then be directly correlated to a specific octane value as per ASTM method specifications [6,8]. The figure 1 appeared blended bioethanol from 0%, 5%, 10%, 15%, 20% of gasoline 88 can increase value research octane number namely: 0%, 3%, 5%, 9%, 11%. The effect of blended bioethanol with gasoline will more significance for characteristic octane number if the base gasoline had lower octane number.

Conclusion
The effect of bioethanol blending on fuel showed an increase in the octane number values for all three fuels tested in this research. The significant increase occurred when using the gasoline 88 blended with 20% volume of bioethanol. The RON (Research Octane Number) value's is increased to 11%, while the MON (Motor Octane Number) is increased to 12% of the previous value. The increase in octane value itself is due to the bioethanol's octane number which is higher than the octane number of gasoline.
The increase in octane number value is obviously also increased its AKI (Anti Knocking Index) values. This indicates that bioethanol should be able to help avoid knocking on the engine when added in the fuel.