Experimental Investigation on the Effect of Fuel Additives on Homogeneous Charge Compression Ignition (HCCI) Engine Combustion

摘要

The experimental research of homogeneous charge compression ignition (HCCI) combustion process was carried out on a 4-cylinder diesel engine. The fourth cylinder of the diesel engine was modified for HCCI combustion with additives. The influence of additives on the HCCI combustion process was investigated. The experimental results indicated that the ignition timing of the base fuel (PRF 90) which is equivalent to gasoline RON 90 without additives delays and the peak of the rate of heat release is low at steady operating conditions on HCCI combustion. Moreover, the ignition timing of the base fuel with additives advances obviously and the peak of the heat release rate increases. At the conditions with the same fuel injection quantity per cycle and the same engine speed, with the increase of the additive concentration in the fuel, the ignition and heat release timings bring forward and the peak of heat release rate increases. However, excessive additives will make the engine be prone to knock and run rudely. In addition, the experiment results indicated that the mixed additives were better than any of the single additives for HCCI fuel, causing ignition and heat release timings further advanced and the peak of heat release rate further increased at different engine speeds and steady operating conditions. Moreover, with the increase of engine speed, the influence of mixed additives on HCCI combustion was more obvious. Furthermore, the mixed additives were beneficial to improve HCCI engine misfire at the high engine speeds, making the engine operating stably.