Effects of Alcohol-gasoline Blends on Exhaust and Noise Emissions in Small Scaled Generators

The increasing industrialization and motorization of the world has led to a step rise for the demand of petroleum-based fuels. Petroleum-based fuels are obtained from limited reserves. These finite reserves are highly concentrated in certain regions of the world. Therefore, those countries not having these resources are facing energy/foreign exchange crisis, mainly due to the import of crude petroleum. Hence, it is necessary to look for alternative fuels which can be produced from resources available locally within the country such as alcohol, biodiesel, vegetable oils etc. 1 . The simple approach to the use of alcohols in spark ignition (SI) engines is to blend moderate amounts of alcohols with gasoline. The second and more technically challenging option is to use alcohols essentially neatly as engine fuel 2 . Alcohols such as methanol (CH3OH), butanol (C4H9OH) and ethanol (C2H5OH) have received considerable attention recently because they are considered as highly efficient, and low-polluting future fuels through their lean operating ability 3 . Alcohol burns cleaner than regular gasoline and produce lesser carbon monoxide, HC and oxides of nitrogen 4 . Alcohol has higher heat of vaporization; therefore, it reduces the peak temperature inside the combustion chamber leading to lower NOx emissions and increased engine power. The oxygen presence in alcohol fuel provides soot-free combustion with low particulate level. Methanol’s most desirable features its high octane quality. Methanol rates 106-115 octane numbers by the research method and 88-92 octane numbers by the motor octane method 5 . Because of these characteristics, methanol is considered to be one of the most likely alternative automotive fuels for SI engines in the foreseeable future 6 . Iso-butanol (C4H9OH) is an attractive alcohol fuel because of its high heating value compared to methanol and ethanol. Iso-butanol heating value represents 77 % of gasoline heating value, and it has the advantages of a low affinity for water solubility in blends 7 . The high octane number of iso-butanol makes it inherently adaptable as fuel for conventional spark ignition engine 8 . Various studies were performed related to the usage of alcohols-gasoline blends in spark ignition engines. The effect of methanol and butanol addition to gasoline on brake specific fuel consumption (b.s.f.c.), exhaust gas temperature, and thermal efficiency has been experimentally investigated 9 . The performance measurements show that there is an increase in b.s.f.c. when using alcohol-gasoline blends, and b.s.f.c. of a butanol-gasoline blend is less than for a methanol-gasoline blend. The experimental results show that the engine thermal efficiency was decreased when fueled with alcohol-gasoline blends. Alasfour 10 investigated the ef-