Presentations

Effect of inhomogeneity of combustion chamber has been thought as one of the way to avoid dramatically generating heat in HCCI Combustion. The purpose of this research is to investigate the effect of inhomogeneity, especially thermal stratification, HCCI Combustion fueled with DME, n-Butane, n-Heptane and iso-Octane. Thermal stratification is made in Combustion Chamber of Rapid Compression Machine with pre-mixture by buoyancy effect. The Pre mixture is adiabatic compressed and on that process, in cylinder gas pressure and two-dimensional chemiluminescence images are measured and analyzed.

The Homogeneous Charge Compression Ignition (HCCI) engine is possible to achieve high thermal efficiency and low emissions. One of the main challenges with HCCI engines is structuring the systems to control combustion phasing, crank angle of 50% heat release (CA50), for keeping high thermal efficiency and avoiding an excessive rate of pressure rise which causes knocking, when operating conditions vary. Though some HCCI combustion control systems, for example Variable Valve Timing System and Variable Compression Ratio System, have been suggested, these control systems are complex and heavy.

The purpose of this study was to gain a better understanding of the effects of in-cylinder gas temperature stratification on reducing the pressure-rise rate in HCCI combustion. HCCI combustion was investigated using an optically accessible engine and direct visualization of the combustion chemiluminescence. The engine was fueled with Di-Methyl Ether. Computational work was conducted on the gas compression and expansion strokes in HCCI engine with simple 0-dimensinal multi-zones model.