Alternative Fuels for Spark Ignition Engines

ABSTRACT

In order to reduce the atmospheric pollution emitted by automobiles, control devices are being incorporated in the vehicles in many countries. This has resulted in a reduced vehicle mileage to the extent of about fifteen percent. Without the introduction of new technology, any further reduction in emission levels would be expected to extract payment in the form of further fuel economy losses. It is, therefore, worthwhile to look into the suitability of “clean” burning fuels for use in internal combustion engines and assess their potential for reducing engine exhaust emissions. So the investigation of alternative fuels becomes very necessary.

In this work three types of fuels are investigated: Alcoholic fuels, gaseous fuels and liquid fuels.

Their properties were inserted in a computer program which was specially designed to calculate the performance of a spark ignition engine over wide range of operating conditions (design and off-design). The design operating variable namely compression ratio, advance angle, engine speed and spark advance were chosen for each fuel based on the physical and chemical properties and the resulting fuel-engine interactions such as mixing, flammability and knock. The resulting performance includes power, specific fuel consumption and thermal efficiency. Their variation with equivalence ratio, engine speed and spark advance was calculated and plotted in the figures and briefly mentioned in the conclusions.

The engine variables including temperature, pressure and volume were calculated at different points of the cycle. Hence the P-V and the P-rc diagrams were drawn for the different alternative fuels. These diagrams are considered unique contribution to the characterization of alternative fuels.