Abstract
Keywords:HCCI, Direct Injection, Natural Gas, PCCI, Dual Fuel
Homogeneous Charge Compression Ignition (HCCI) is an internal combustion process that is difficult to implement in a production setting due to the lack of direct control over combustion timing. A direct injector has been adapted to a single cylinder research engine to initiate and control the combustion of a pre-mixed natural gas charge by introducing a stratified charge near top dead center. N-heptane is used as the direct injected fuel as its low autoignition temperature allows for a predictable ignition delay of the main charge. The effect of the pilot charge on combustion timing, stability, and severity is investigated, as well as the extension of the load range of the engine.