Performance studies with biomass-derived high-octane fuel additives in a two-stroke spark-ignition engine

Abstract

The intensive search for alternative fuels for spark-ignition engines has focused attention on fuels which can be derived from biomass. In this regard, orange oil and eucalyptus oil are found to be potential candidates for spark-ignition engines. Their properties are similar to gasoline in nature and they are miscible with gasoline without any phase separation. They can be used in spark-ignition engines with little engine modification as a blend with gasoline fuel. The high octane value of these fuels can enhance the octane value of the fuel when it is blended with low-octane gasoline. Hence, the knock-limited compression ratio (CR) can be further increased when these fuels are blended with gasoline. In the present work, 20% by volume of orange oil and eucalyptus oil were blended separately with gasoline and the performance, combustion and exhaust emission characteristics were evaluated at two different compression ratios. Test results indicate that the performance of fuel blends was much better than the gasoline fuel, in particular at the higher compression ratio. Hydrocarbons and carbon monoxide emission levels in the engine exhaust were considerably reduced with the fuel blends at both the compression ratios tested. Between the two fuel blends tested, eucalyptus oil blend provides better performance than the orange oil blend. The maximum percentage improvement in the brake thermal efficiency obtained with eucalyptus oil blend is about 20.5% at 2 kW, 3000 r.p.m. and CR 9 over the normal gasoline engine.