A mathematical model of the compression, combustion, and expansion phases of the divided chamber spark ignition engine is reported here. This model has been developed in an attempt to combine as many as possible the basic characteristics of the divided chamber spark ignition engine combustion. It is used to compare the predicting performance and emission levels when operating the engine with hydrogen, alcohol and isooctane fuels. A procedure for incorporating simple kinetic mechanisms for NO formation and CO oxidation is built into the model.
The divided chamber engine is treated as a pair of two thermodynamic sub-systems (prechamber and mainchamber systems)coupled by mutual mass flow. The results obtained are related to such important practical questions as the effect of prechamber volume ratio, connecting orifice size, fuel type and degree of charge stratification, on predicting performance and emission levels. This study shows that the divided chamber engine performance and emission levels are strongly affected by these design parameters. The results also indicated that improvement in engine performance and emission levels have been fulfilled when using hydrogen and alcohol fuels than that with isooctance.
Moreover, two stage combustion results in a loss of power compared to conventional spark ignition engine. This might be more compensated in practice. The reasons for this power loss and possible means of compensating are discussed here.