Abstract
Keywords:
Partial homogeneous charge compression ignition, Premixed fuel, Normal-heptane
Abstract
Normal-heptane is regarded as a fuel with a relatively low boiling point and good ignition characteristics for HCCI combustion. Effects of the premixed n-heptane fuel on the combustion and emission characteristics in a DI diesel engine are experimentally investigated in this work. Normal-heptane for premixed fuel is supplied by the additional fuel injection system in the intake manifold of direct injection diesel engine and the injection nozzle for directly injected fuel is equipped in the center of combustion chamber. The air temperature control system and EGR system are equipped in the intake manifold to examine the effects of various factors such as air temperature and EGR rate. From the results of this work, the rate of heat release shape for n-heptane premixing shows three-stage combustion of cool flame, HCCI combustion and diffusive combustion of a DI fuel. When the premixed n-heptane is vaporized completely by charge heating, soot is not formed during HCCI combustion of premixed fuel, and dependent on the amount of DI fuel.