Self-Ignition of Diesel Sprays and Its Dependence on Fuel Properties and Injection Parameters

The self-ignition process in diesel engines is influenced by many parameters, which are partially interrelated. In order to separate the influence of basic parameters, a special high-pressure, high-temperature vessel has been designed that allows injection in short intervals under defined and repeatable conditions. The evaluated parameters include: cetane number, viscosity and volatility, vaporization behavior, and ignition improving additives. In addition to other factors, the investigations showed that the cetane number itself is not sufficient to characterize the self-ignition properties especially of heavy fuels and fuels containing ignition improvers. Additionally, the influence of injection parameters was evaluated, including injection quantity, pressure level, and nozzle design.