Investigation of Diesel/Natural Gas RCCI Combustion Using Multiple Reaction Mechanisms at Various Engine Operating Conditions
Past experimental studies conducted by the current authors on a 13 liter 16.7:1 compression ratio heavy-duty diesel engine have shown that diesel /natural gas Reactivity Controlled Compression Ignition (RCCI) combustion targeting low NOx emissions becomes progressively difficult to control as the engine load is increased due to difficulty in controlling reactivity levels at higher loads. For the current study, CFD investigations were conducted using the SAGE combustion solver in Converge with the application of Rahimi mechanism. Studies were conducted at a load of 5 bar BMEP to validate the simulation results against RCCI test data. In the low load study, it was found that the Rahimi mechanism was not able to predict the RCCI combustion behavior for diesel injection timings advanced beyond 30bTDC. This behavior was found at multiple engine speed and load points.