A Dual-Fuel System to Achieve High Equivalence Ratio and High Engine Performance in Homogeneous Charge Compression Ignition (HCCI) Mode

A Dual-fuel system has been developed to achieve a large operation range with HCCI mode. The engine could run on equivalence ratio of 0.30 to 0.50 using N-heptane. A secondary fuel, iso-octane was injected at the points of equivalence ratio between 0.40 and 0.50. It's found extending operation point to equivalence ratio of 0.60. The required intake charge temperature distribution was lesser from 75° to 25°C. Maximum thermal efficiency was 46%. HC and CO emissions were improved which keep lower than 650 ppm and 0.8% correspondingly. NO_x emissions increased rapidly at high load to maximum of 500 ppm