A Review of HCCI Engine Using Alternative Fuels

Abstract

In today’s day and age, automotive as an industry is actively exploring alternative combustion phenomenon’s to substitute Spark Ignition (SI) and Compression Ignition (CI) systems for Internal Combustion (IC) engines. With a distinctive set of features, Homogeneous Charge Compression Ignition (HCCI) engines hold a promising position as a feasible alternative, as besides low emissions of Nitrogen Oxides (NOx) and soot, HCCI also ensures plausible merits of high volumetric efficiency. In principle, the combustion auto-ignites at multiple spots once the mixture has reached its chemical activation energy as there is no spark plug or injector to assist the combustion. The important challenges encountered in developing HCCI engines are: (i) Uncontrolled combustion and Self-ignition of the working fluid with fuel,(ii) the maximum pressure at high load operations,(iii) To rectify the problem of cold starting,(iv) reaching the emission standards and (v) to control the phenomenon of  knocking. At low engine speeds, a probable early auto-ignition can lead to knocking, while at high engine speeds, delay auto-ignition would make HCCI susceptible to misfire. The emission levels are greatly reduces by hydrogen but renders reduced power. However, lower NO_x, CO and particulate matter (PM) emissions levels can be achieved by combining hydrogen with diesel in dual-fuel mode, and the efficiency of the engine can be increased.  HCCI engines performance (i.e. emissions levels, brake thermal efficiency and combustion phasing) is usually predicted by numerical methods, which are cost effective compared to entirely relying on empirical data