Characterisation of the combustion process in the spark ignition and homogeneous charge compression ignition engine

Abstract

Homogeneous charge compression ignition (HCCI) engine is a potential solution for reducing air pollution and for satisfying legal limits regarding the emissions from internal combustion engines. The HCCI engines have advantages of lower emissions of NOx and particulate matter, compared to the standard combustion modes, while on the other hand one of the major disadvantages is the difficulty of control of start of combustion, since the start of combustion is highly sensitive to the intake air temperature. Additional advantage of the HCCI engine is the abil-ity to operate with wide range of fuels. In order to demonstrate this potential in this study the HCCI mode of operation is compared to the spark ignition mode of operation. The study aims to compare and characterise two different combustion modes on the same engine with different CR and different fuels at similar operat-ing conditions. For that purpose the engine tests are performed at the same indi-cated mean effective pressures for the spark ignition and HCCI combustion mode at the same engine speed, while the tests are performed at three different engine speeds and three different loads. The measurements were performed on the ex-perimental set-up that consists of single cylinder Diesel engine modified to ena-ble operation in spark ignition and HCCI modes. The characterisation includes the comparison of in-cylinder pressure, temperature and rate of heat release ob-tained by spark ignition and homogeneous charge compression ignition combus-tion mode and presents comparisons of engine efficiencies and of emissions of HC, CO, and NOx.