Effects of diesel components on ignition and combustion characteristics of the diesel engine under different oxygen concentrations

The plateau environment would cause a series of problems, such as difficult cold start, incomplete combustion, decreased thermal efficiency and insufficient power. Although many methods have been used to solve these problems, the most critical is to start from the fuel itself, there is a necessity to investigate the design of diesel fuel composition in high altitude and oxygen-deficient environment. Therefore, this study aims to reveal the effects of different diesel components on the ignition and combustion characteristics at low oxygen concentration, and to provide a theoretical basis on fuel design strategy. An optimized DPCS model was used to develop a six-component diesel surrogate capable of reproducing the physicochemical properties of diesel fuels. Then, the KIVA-3V code coupled with CHEMKIN was established to model the ignition and combustion process and verified with the experimental results. Furthermore, the effects of different diesel components of the diesel surrogate on ignition and combustion behaviors were investigated. The results indicated that the incomplete combustion loss increased at low oxygen concentration, and the effect on IMEP was dominant. In addition, at low oxygen concentration, CA10 was delayed and affected the combustion efficiency more significantly, the combustion duration was prolonged, and the pressure rise rate was nearly linear with CA10. In addition, HMN and n-hexadecane were the predominate components affecting CA10, combustion duration, pressure rise rate and IMEP, thus it was particularly critical to adjust the proportion of these two components when designing the fuel.