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A single cylinder direct injection (DI) diesel engine is modified to run in HCCI-DI mode using a novel in-cylinder dual injection strategy. In this present investigation effect of 2nd injection timing, premixed equivalence ratio and exhaust gas recirculation (EGR) on combustion and emission behavior is studied. Based on the characteristics of combustion, performance and emission behavior, 2nd injection timing is optimized at a constant split ratio (80%) and engine speed (1500 rev/min). Premixed equivalence ratio was varied (up to 0.38) at the optimized 2nd injection timing condition. It is identified that 2nd injection timing and premixed equivalence ratio play an important role in controlling the occurrences of all combustion parameters of HCCI-DI combustion. EGR was introduced in the cylinder to understand its effect on various combustion parameters and emission behavior.

Homogeneous Charge Compression Ignition (HCCI) combustion was studied as a means of reducing PM and NOx emission simultaneously while maintaining high thermal efficiency and lower fuel consumption. An innovative low cost dual injection strategy is developed to investigate HCCI-DI combustion. This study is focused on the effect of fuel properties and cetane number on HCCI-DI combustion to understand the combustion and emission behavior of a direct injection HCCI engine using double injection strategy with blends of n-heptane and isooctane as fuel. A comparison is also made to understand the behavior and benefits of HCCI-DI combustion over the conventional combustion system. All experiments were carried out at a constant speed of 1350 rev/min and at zero, 15% and 30% of the full load conditions to avoid high knock intensity for high cetane fuel which occurs beyond this operating load condition.