ANALYSIS OF DEVELOPMENT OF HCCI FUEL COMBUSTION ENGINE

When gas prices increase, more attention on environment, air pollution and climatic changes revived research interest on use of alternative fuel sources. Due to emission standards, the generally important researches carry out in the field of ICE, on Diesel engines, and fuel consumption. One way to reach this goal is to using new combustion concepts, such as Homogeneous Charge Compression Ignition. Homogeneous Charge Compression Ignition (HCCI) engines promise high thermal efficiency as compression-ignition direct-injection (CIDI) engines (an advancement of existing diesel engine), and producing ultra-low oxides of nitrogen (NOx) with exhaust gas recirculation (EGR) and particulate matter (PM) emissions, since HCCI has increased HC and CO emissions. HCCI engines incorporate with the best features of both spark ignition (SI) gasoline engines and CIDI engines. In SI engine, the charge is well mixed which minimizes particulate emissions, and CIDI engine it is compression has no throttling losses, which leads to high efficiency. There is no direct control method for auto ignition time. The common way to controlling the ignition timing in HCCI combustion engine is by varying engines parameters, which can affect the combustion. By the principle of using dilute, premixed charge that reacts and burns volumetrically throughout the cylinder as it is compressed by the piston. HCCI combustion is depending upon by controlling the pressure, temperature and composition of the fuel air mixture so that it spontaneously ignites in the engine. Engine and car manufacturers are experiencing the demand concerning fuel efficiency and low emissions from both consumers and governments. Homogeneous charge compression ignition (HCCI) is an alternative combustion technology that is cleaner and more efficient than the other types of combustion. Although the thermal efficiency and NO𝑥 emission of HCCI engine are greater in comparison with traditional engines, HCCI combustion has several main difficulties such as controlling of ignition timing, limited power output, and weak cold-start capability. In this study a literature review on HCCI engine has been performed and HCCI challenges and proposed solutions have been investigated from the point view of Ignition Timing that is the main problem of this engine. HCCI challenges are investigated by many IC engine researchers during the last decade, but practical solutions have not been presented for a fully HCCI engine. Some of the solutions are slow response time and some of them are technically difficult to implement. So it seems that fully HCCI engine needs more investigation to meet its mass-production and the future research and application should be considered as part of an effort to achieve low-temperature combustion in a wide range of operating conditions in an IC engine.