Transcritical injection is of relevance to many areas of science and engineering. In all applications, one of the most controversial issue is the prediction of the transition point from two-phase to single phase mixing. In this work, we have analysed the applicability of recent transition models, e.g. the Knudsen criterion developed originally for propulsion applications, to analyse the formation and development of mixing layers of carbon dioxide and different organic solvents. Results show that global equilibrium models fail to predict the experimental behaviour reported in the literature and exhibit an inconsistent trend among the different organic solvents/CO₂ mixtures. This implies that initial conditions alone are not sufficient to determine the evolution of the mixing layer. As a consequence, research efforts should be directed to the accurate description of the coupled energy and mass diffusive fluxes both at the liquid–gas interface and in the surrounding gaseous mixing layer.

跨临界注入与科学和工程学的许多领域都息息相关。在这项工作中，使用平衡模型检查了二氧化碳和有机溶剂的混合层，并使用了最近开发的理论对气液界面进行了分析。结果表明，这些模型无法预测文献中观察到的实验行为。因此，研究工作应针对热，动量和质量扩散通量的完整描述，以及将直接数值模拟用于研究这些复杂的混合层。