Abstract:

Homogeneous charge compression ignition (HCCI) engines have significant advantages over spark ignition (SI) and compression ignition (CI) engines due to their high thermal efficiency and low NOx emissions. However, it is difficult to control the start of combustion. In this study, the effects of the intake manifold pressure on HCCI combustion were investigated experimentally at 373 K intake temperature in a four cylinders HCCI engine, which was transformed from the SI engine. It was observed that there was an advance in the start of combustion as the manifold pressure increased. It was also observed that the change in octane number had significant effects on the start of combustion. The highest thermal efficiency was recorded as 46.38% at 120 kPa manifold pressure using RON40 fuel. The increase in the volumetric efficiency that depends on the increase in manifold pressure provided an increase in maximum cylinder pressure and heat release.

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