Experimental Investigation on Compound Combustion of Partial Premixed Charge Compression Ignition -Direct Injection Engine Fueled with Dimethyl Ether

摘要

In order to enlarge the operating range at HCCI (Homogeneous Charge Compression Ignition) mode and explore the scientific methods to realize the ultra-low emission with DME ( Dimethyl Ether) as alternative fuel. Experimental investigation on the realization 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. The method to achieve the PCCI-DI mode is that feeding part of DME into intake pipe to produce Pre-mixed homogeneous mixture and injecting the other part of the DME fuel into the combustion chamber by the original fuel injection device in the late stage of compression stroke. Results indicate that the engine can be operated at a wider range of speeds and loads at PCCI-DI mode. The brake thermal efficiency increases and NO_X emission reduces. However, HC and CO emission increase. It is also indicated from experiments that NO_X, HC and CO emission increase with an increase of DME premixed quantity. Furthermore, the optimum fuel supply advance angle for PCCI-DI mode could be delayed 6~8°CA on the base of DME DI mode.