The Effects of Premixed Ratios on the Performance and Emission of PPCCI Combustion in a Single Cylinder Diesel Engine

Abstract

In diesel engines simultaneous reduction of NOx and Particulates (PM) is a challenging task for researchers. Different strategies, such as retarding injection timing, increasing injection pressure, employing common rail fuel injection system, pilot injection, multi-injection, pre-mixed charge compression ignition (PCCI), Homogeneous Charge Compression Ignition (HCCI), EGR, and after treatment devices are adopted to reduce the NOx and PM emissions. In this work an attempt is made to reduce NOx and PM using partially premixed charge compression ignition (PPCCI) combustion mode with diesel as fuel in a single cylinder diesel engine. Part of the fuel is injected into the intake manifold to form homogeneous premixture beforehand and the premixture is burnt in the cylinder with the balanced quantity of fuel directly injected into the cylinder by a conventional injection system. The premixed fuel ratio (Rp) was varied from 25%, 50%, and 75%. The Premixed ratio (Rp) is defined as the ratio of the energy of premixed fuel to the total energy supplied. Due to homogenous lean operation, significant reductions of NOx and smoke are achieved.