Study on HCCI Combustion Fueled with DME

A 2135 C.I. engine was modified to work at the DME HCCI combustion mode with compression ratio of 16.5. The experimental results showed that DME HCCI combustion could give almost zero NO_x emission and smokeless behaviors. Within the narrow range of A/F ratio, CO emission decreased with the increase of engine load, while little variation in HC emissions presented. The HCCI combustion of DME gives an obvious two-stage combustion characteristic. Since the early ignition of DME (28° CA BTDC), the engine can be operated with a limited low-medium loads. In order to control the ignition timing and extend the operating range, LPG was added in DME to lowering the cetane number or introducing CO_2 into the intake fresh air. The results showed that these two approaches could effectively control the HCCI combustion and extend engine operating range.