HCCI Combustion of Hydrogen, Carbon Monoxide and Dimethyl Ether

Homogeneous charge compression ignition (HCCI) combustion enables higher thermal efficiency and lower NOx emission to be achieved in internal combustion engines when compared with conventional combustion systems. Control of proportion of high cetane number and low cetane number fuels is an effective technique for controlling ignition timing and load in HCCI combustion.

The aim of this paper is to analyze the characteristics of the HCCI combustion of hydrogen, carbon monoxide and dimethyl ether (DME) in a single cylinder engine. A mixture of hydrogen and carbon monoxide with a composition of 67% hydrogen and 33% carbon monoxide called methanol-reformed gas (MRG) was used as the low cetane number fuel and DME as the high cetane number fuel. Both MRG and DME can be reformed from methanol in endothermic reactions. The endothermic reactions make waste heat recovery in fuel reforming possible by using the heat from the exhaust gases. Experiments were conducted in which the proportion of the fuels, equivalence ratio and compression ratio were varied to control ignition timing.

The results show that the HCCI combustion of hydrogen, carbon monoxide and dimethyl ether has a high thermal efficiency over a wide operating range. HCCI combustion has a high power output that is comparable to that of SI combustion despite lean combustion conditions, because of the high thermal efficiency.