In mixing controlled Diesel combustion concept, mixing processes are a key phenomenon that significantly effects power, efficiency and emissions. A consequence of fuel-air-mixing is fuel phase change, which is not fully understood yet. In this study, phase change mechanisms of sprays of different n-alkanes at high pressure and temperature conditions are investigated. Mie scattering imaging is utilized to obtain the maximum liquid penetration of Diesel surrogates (hexane, heptane, decane and dodecane) injected into nitrogen atmosphere in a constant volume chamber at fuel supercritical temperature and ambient pressures ranging from sub- to supercritical. Two 1D models are utilized to predict the liquid length based on the required enthalpy for full phase change. The theoretical models are validated against experimental data to identify phase change regimes. Along with ambient conditions, fuel properties significantly influence the phase change mechanism in a spray. Especially fugacity plays an important role regarding the droplet evaporation rate.

在混合控制柴油机燃烧概念中，混合过程是严重影响功率，效率和排放的关键现象。燃料-空气混合的结果是燃料相变，这尚未完全被理解。在这项研究中，研究了在高压和高温条件下不同正构烷烃喷雾的相变机理。利用三重散射成像来获得在燃料超临界温度和范围从亚临界到超临界的环境压力下，在恒定容积室内注入氮气气氛的柴油替代物（己烷，庚烷，癸烷和十二烷）的最大液体渗透率。利用两个一维模型基于完全相变所需的焓来预测液体长度。理论模型针对实验数据进行了验证，以确定相变机制。与环境条件一起，燃料特性会显着影响喷雾中的相变机理。特别是逸度对于液滴的蒸发速率起着重要的作用。