Comparison of performance and emission characteristics of homogeneous charge compression ignition with conventional compression ignition engine

The performance and emissions of homogeneous charge compression ignition (HCCI) diesel engines were analysed at varying intake air temperatures (Ti) and compared with conventional diesel engines. HCCI engines featured outside fuel–air mixing systems. Diesel was used as a fuel for the testing of port fuel injection pressure (two bars, four bars, and six bars), as well as intake temperature Ti (60 °C, 80 °C, 100 °C, 120 °C, and 140 °C). The outcomes of the experiments presented that both Ti and port fuel injection pressure had a substantial impact on the fuel–air mixture. Up to 120 °C, the blending of air and fuel had a proportionate effect on Ti. When heated above 120 °C, it caused significant knocking and emissions. The Brake thermal efficiency of HCCI is similar to that of diesel engine when HCCI engine operated at an intake air temperature of 120 °C and injection pressure of 4 bar where as in other modes it less than the efficiency of diesel engine. The nitrogen oxide emissions were significantly reduced in the all HCCI engine mode operations compared to diesel engine. The minimum emissions were engine when HCCI engine operated at an intake air temperature of 120 °C and injection pressure of 4 bar. The smoke opacity was significantly reduced in the all HCCI engine mode operations compared to diesel engine. The minimum emissions were engine when HCCI engine operated at an intake air temperature of 120 °C and injection pressure of 4 bar. The HC and CO emissions of HCCI engine at all conditions were slightly higher than the diesel engine. But, the minimum emissions were obtained when HCCI engine operated at an intake air temperature of 120 °C and injection pressure of 4 bar without knocking. Finally, it is concluded that HCCI engine operated at an intake air temperature of 120 °C and injection pressure of 4 bar will give the optimized perform ace and emission characteristics when compared to diesel engine.