Experimental Research on Combustion Characteristics of PCCI–DI Engine Fueled with Dimethyl Ether

Abstract

The use of clean alternative fuel and new combustion mode is one of the most effective methods of further reduction of NOx and smoke emissions at diesel engine. High thermal efficiency and ultra-low NOx and PM emission of engine in HCCI combustion mode can be realized at low and medium load. However, some problems such as hard control of ignition timing and narrow operating range still exist.For the sake of expanding the operating range of HCCI (Homogeneous Charge Compression Ignition) engines and explore the scientific methods to realize the ultra-low emission with DME (Dimethyl Ether) as alternative fuel. Experimental Research on the characteristics of PCCI-DI (Partial Premixed Charge Compression Ignition – Direct Injection) combustion is carried out on a single cylinder and naturally aspirated direct injection diesel engine. Results indicate that PCCI-DI DME engine has lower peak cylinder pressure and lesser rise rate of pressure. The engine also shows up an obvious two-stage heat-release characteristic. Compared with HCCI DME engine, peak value of two heat-releases reduces, the position of the first peak almost has no change and the position of the second peak shifts to the position later than TDC (Top Dead Center).