Comparison and analysis of the combustion process of three combustion modes of an ethanol - diesel direct injection engine

Abstract

A diesel engine was modified into an ethanol - diesel direct injection engine. Diesel was injected through the engine’s original pump injection system, whereas ethanol was injected through an installed electronic controlled injection system. 100% of ethanol injection at 240°CA (referred to as B100), 50% of ethanol injection at 240°CA and 50% injected subsequently with diesel at 344°CA (referred to as B50L50) and 100% of ethanol injection with diesel at 344°CA (referred to as L100) were the three combustion modes. Based on test data, a 3D combustion chamber model was established for the analysis of the combustion modes. The result showed that B50L50 had the earliest combustion starting point, the highest combustion pressure and maximum average temperature in the cylinder, the largest maximum cumulative heat release and sufficient combustion. In addition, NO generation was the highest but the soot generation during the initial combustion period was not the highest even though it was high. The soot generation of B100 was the highest. For L100, the combustion starting point was the latest, after burning was severe, cylinder pressure and maximum temperature were lower, NO and soot generation were the lowest, but CO generation was the highest, comparatively.