A SIMULATE MODEL FOR ANALYZING THE EFFECT OF ENGINE DESIGN PARAMETERS ON THE PERFORMANCE AND EMISSIONS OF SPARK IGNITION ENGINES

A mathematical and simulation model has been developed to simulate a spark ignition engine operation cycle. The programme written from this simulation model and modified so can be used to assist in the design of a spark ignition engine for alternative fuels as well as to study many design parameters such as the effect of engine design parameter like stroke and diameter of the cylinder on the performance and exhaust emissions of spark ignition engines. In this paper, the description of three type of engines design parameters according to (stroke/diameter) which are called under square, square and over square engines using three type of fuel (gasoline, LPG, CNG) singly have been taken. The variations of power output, thermal efficiency, specific fuel consumption, ignition delay, temperature of exhaust gases, heat loss and the exhaust emissions (CO2, CO, NO, O2) by volume, were calculated for each type of engine and then comparing the results to investigate how to increase engine efficiency and reduce exhaust emissions. The accuracy of the present model is confirmed by comparison with experimental result that have established by previous literatures and the results were agreement with literatures. The main results obtained from the present study shows that, the square engines (S/D=1) can be considered as most efficient, modern and suitable design for engines running by gasoline and alternative fuels like LPG and CNG, because of higher power output due to the suitable piston area for pressure distribution. The area of flame front which may create higher combustion qualities and higher thermal efficiency through faster burning and lower overall chamber heat loss, also, the potential of the square engines (S/D=1) for indicate specific fuel consumption was 4% improved