Test Research on the Knock of a Common-Rail Diesel Engine Fueled with Diesel-Methanol Dual-Fuel

Abstract

Experiments were conducted on a diesel-methanol dual-fuel (DMDF) engine modified by a six-cylinder, turbo-charged, inter-cooled diesel engine. According to the number of diesel injection, the experiments are divided to two parts: the single injection mode and double injection mode. The results show that, at the double injection mode, the maximum of pressure rise rate is small and the engine runs smoothly, however, knock still occurs when the co-combustion ratio (CCR) is big enough. Under knock status, the power density of the block vibration concentrating at some special frequencies rises dramatically, and the special frequency of single injection mode (about 4.1 kHz) is lower than that of double injection mode (7–9 kHz). The cylinder pressure oscillations of knock status are very different from the non-knock status. Under knock status, cylinder pressure oscillations become more concentrated and fiercer at some special frequencies, and the same as the block vibration. The special frequency of single injection mode (3–6 kHz) is lower than that of double injection mode (above 9 kHz).