Homogeneous Diesel Combustion with External Mixture Formation by a Cool Flame Vaporizer

The homogeneous Diesel combustion is a way to effect a soot and nitrogen oxide (NO_x) free Diesel engine operation. Using direct injection of Diesel fuel, the mixture typically ignites before it is fully homogenized. In this study a homogeneous mixture is prepared outside of the combustion chamber by a Cool Flame Vaporizer. At first the specification of the vaporizer is given in this paper. To determine the composition of the vaporizer gas an analysis using gas chromatography/mass spectroscopy (GC/MS) was made. The results give an idea of the effects on engine combustion. Followed by, the vaporizer was adapted to a single-cylinder Diesel engine. To adapt the engine's configuration regarding compression ratio and inlet temperature range a zero dimensional engine process simulation software was utilized. The engine was run in different operating modes. The test results with external mixture formation were compared with two low temperature Diesel combustion strategies based on direct fuel injection: the Premixed Charge Compression Ignition (PCCI) and the Late Low Temperature Combustion (LLTC).