Homogeneous Charge Compression Ignition (HCCI) Combustion of Diesel Fuel with External Mixture Formation

The current direction of most published diesel HCCI research is mixture preparation using the direct injection – system, referred to as internal mixture formation. The alternative to the internal mixture formation is, predictably, external mixture formation. The key to the external mixture formation with diesel fuel is proper preparation. In this study a fuel vapouriser was used to achieve excellent HCCI combustion in a single cylinder air-cooled direct injection diesel engine. No modifications were made to the combustion system. In the present investigation a vaporized diesel fuel was mixed with air to form a homogeneous mixture and inducted into the cylinder during the intake stroke. To control the early ignition of diesel vapour-air mixture, cooled EGR technique was adopted. Experiments were conducted with diesel vapour induction without EGR and with 10%, 20% and 30% EGR. The results are compared with conventional diesel fuel operation (Dl @ 23 deg bTDC and 200 bar nozzle opening pressure). The combustion, emission and performance parameters were analyzed. The results obtained from this study shows that NOx emissions reduce by 95% and smoke emissions by 83%. The observed trend was matching with the research findings of other external mixture formation studies.