Mixing at transcritical conditions

两种流体化合物的混合过程是跨临界的，即两种流体（混合前）的初始状态不能明确预测混合将以单相还是两相进行。尽管在跨临界条件下的混合广泛应用于推进系统和柴油发动机，在新型CryoPower回收分裂循环发动机（RSCE）和高压过程中产生颗粒，但我们对不同机制（两相与单相混合）在混合物形成中的相关性还没有明确的认识。因此，对于如何最好地模拟跨临界混合以可靠地反映相关机制，目前还没有达成共识。关于跨临界混合过程的定量实验见解的数据可用性是罕见的。因此，本提案的主要目的是实验提供沿真实跨临界混合路径轨迹（工作包2和3）的定量混合物组成和温度偶，这在未来可以作为建模方法的定量参考。实际与理论混合路径轨迹的比较（工作包4和5）将揭示在多大程度上(i)偏离热力学平衡，（ii）相界面的退化和（iii）由于额外的热扩散和质量扩散而导致的能量和质量传输的不同速率，必须在描述跨临界混合过程的模型中考虑。定量成分/温度数据（空间分辨）将通过各种互补光学测量技术的组合提供。在很大程度上，该项目是基于现有成分或温度数据的利用，通过该提案，将补充到高价值的相关成分和温度数据对。

Mixing processes of two fluid compounds are transcritical, when the initial states of the two fluids (before mixing) do not allow a definite prediction on whether the mixing will take place in a single- or in two-phases. Though mixing at transcritical conditions is widely used in propulsion systems and diesel motors, in the novel CryoPower recuperated split cycle engine (RSCE) and high pressure processes for particle generation, we do not have a clear understanding about the relevance of the different mechanisms (two-phase vs single-phase mixing) involved into mixture formation. As a consequence, there is currently no consensus about how transcritical mixing can be modelled best in order to reliably reflect the relevant mechanisms. The data-availability on quantitative experimental insights into transcritical mixing processes is rare. Therefore, the main aim of this proposal is the experimental provision of quantitative mixture compositions and temperature couples along real transcritical mixing path trajectories (work packages 2 & 3), which in the future can serve as quantitative reference for modelling approaches. The comparison of real vs theoretical mixing path trajectories (work packages 4 & 5), will reveal to which extent (i) the departure from thermodynamic equilibrium, (ii) the degradation of a phase interface and (iii) the different rates of energy and mass transport due to the additional thermal and mass diffusion, have to be regarded in the models for the description of transcritical mixing processes. The quantitative composition/temperature-data (spatially resolved) will be provided via the combination of various complementary optical measurement techniques. To a large extend the project is based on the utilization of already existing either composition or temperature data, which through this proposal will be supplemented to high-value couples of correlated compositional and temperature data.