Homogeneous Charge Compression Ignition Engines

Abstract

Reducing exhaust emissions and increasing the fuel economy of internal combustion engines are of global importance. To meet the demand of economy, energy conservation, less environmental harmful exhaust emissions, especially carcinogenic NOx and responsibility for a greenhouse effect CO2 and higher thermal efficiency present generation engines must be characterized by low fuel consumption, high thermal efficiency, reliability, low price and low cost of usage. Homogeneous charge compression ignition (HCCI) combustion is an alternative to current engine combustion systems; it has the potential nearly to eliminate engine-out NOx emissions while producing diesel- like engine efficiencies, when a pre mixture of gas-phase fuel and air is burned spontaneously and entirely by an auto ignition process. However, due to the absence of an immediate means of stable operation over a wide range of conditions and transient control have proven challenging and have so far prevented commercialization. HCCI engines can operate on gasoline, diesel fuel and most alternative fuels. HCCI combustion is achieved by controlling the temperature, pressure and composition of the fuel and air mixture so that it can spontaneously ignite. This control system is fundamentally more challenging than using a spark plug or fuel injector to determine ignition timing as used in SI and DI engines respectively.