Abstract:

Homogeneous charge induced ignition (HCII) combustion can achieve low emissions and high efficiency. However, the gasoline ratio of HCII combustion at medium and high load is limited by rough combustion. In this paper, a lower compression ratio was utilized to relieve the rough combustion at medium and
high load. This strategy was verified by experiments on a heavy-duty multi-cylinder engine. The results show that by reducing the compression ratio from 18 to 16 the peak in-cylinder pressure is effectively reduced and the gasoline ratio range can be obviously extended. Thus, the combustion and emission characteristics of HCII at medium and high load are noticeably improved. The reduction of soot emissions at specific operating conditions can be close to 50%. These results also have reference value for other dual fuel engines.

Key words: internal combustion engine, homogeneous charge induced ignition (HCII), rough combustion, compression ratio;, gasoline ratio, emission