A multi-component surrogate of commercial diesel for trans-critical and supercritical injections study

摘要

The supercritical diesel combustion concept is expected to increase the engine efficiency and reduce the harmful emissions. The investigations of diesel trans-critical and supercritical injections are the basis to understand this new diesel combustion concept. In order to numerically study the trans/supercritical injection characteristics of commercial diesel, the critical temperature of real commercial diesel was experimentally measured and the method to calculate the critical point of multi-component mixture was verified. A six-component surrogate of commercial diesel was formulated by a model-based surrogate formulation method. The comparisons between the predicted properties of six-component surrogate and the measured data of real commercial diesel were conducted. The results show that the surrogate can emulate many temperature-independent properties (cetane number, lower heating value, critical temperature and distillation temperature) and the temperature-dependent properties (density, viscosity, surface tension and thermal conductivity) with extreme small deviation. These properties have significant effect on sub/trans/supercritical injections of the commercial diesel. In addition, the surrogate was applied to simulate the diesel trans-critical injection with the continuous Euler method. The predicted liquid and vapor penetration have excellent agreement with the measured values.