Abstract
ABSTRACT:
Alternative fuels are an actual solution for improving ecological performances of internal combustion engines. This possibility is considered a low cost/short term outcome. The application has been demonstrated by the actual applications of Liquefied Natural Gas (LPG). The large differences on heat release during a working cycle among different alternative fuels are leading to significant differences of the mechanical output. The simple change of the fuel may be not enough for running applications because of the differences in mechanical output due to different heat release rates of different fuels. The applications may be more extensive if mechanical performances can be maintained. If alternative fuels are a solution for ecological aspects then mechanical solutions can be considered due to their advantages like, simple technology, low mass, efficiency. An alternative that was abandoned because of consumption and emissions, but not for its mechanical performances is the two stroke engine. The paper has the main objective to demonstrate the opportunity to evaluate the solution of two stroke engines with direct injection of alternative and performance compensation by supercharging rate. The analyse process is conducted using the WAVE software that is based on 1D, anisentropic and transient flow and energy balance for the cylinder. The emission simulation is based on a two -zone model for the combustion process. In order to analyse the proposed objective, a gasoline engine with a given geometry is considered working under the 4 and 2 stroke principles. The two stroke solution is evaluated for performance and emissions using alternative fuels. The mechanical differences are compared and the compensation process using supercharging is analysed evaluating also the emissions. The analysis sustains the conclusion that two stroke engines may be considered as high performance simple solutions for using alternative fuels. Mechanical differences for different fuels may be compensated by supercharging.