Experimental investigation of formation mechanisms and rearrangement phenomena of reactive-inert particle layers in cross-flow filters in gas cleaning applications

横流或壁流式过滤器如今是废气后处理中的标准组件，并通过去除灰分和烟灰颗粒来减少内燃机的颗粒排放。在由于层形成而达到临界压降之后，过滤器被再生。烟灰颗粒通过连续（C-NO2）或不连续（O2）反应被氧化。这导致层破裂。颗粒结构可分离并沿过滤器通道沿着输送。在该工艺中，均匀层的沉积图案可以导致沟道填充。颗粒层的破碎行为是一个决定性的过程，取决于层的组成和烟灰反应性。整个项目的目的包括结构化的调查之间的关系的颗粒层的反应性和惰性颗粒和重排过程（层破碎-再悬浮-运输）的颗粒结构在O2-以及NO2为基础的再生在一个模型过滤器通道。在第一个项目阶段，开发了一个实验装置，在该装置中，可以在模型过滤器通道中研究基于O2的再生过程中再悬浮颗粒结构的重排过程。层破碎，团聚体的再悬浮和运输的观察在整个通道长度与高速摄像机和分析的再悬浮位置，团聚体的大小和速度。开发的方法和现有的知识再悬浮过程作为基础的目标，在第二个供资期内定义。因此，第二个项目阶段的目标是从根本上研究烟尘反应性（高反应性与低反应性）和烟尘分散性以及氧化气体（NO2与O2）对壁流式过滤器中重排过程的影响。随后使用所得到的结果来阐明从文献中得到的沉积模式在壁流式过滤器中的不一致性取决于所使用的氧化气体（连续再生（NO2）均匀层;不连续再生（O2）通道填充）。假设追求的是，它不是氧化气体，但基本的粒子技术过程，决定重排行为。通过对工艺参数（例如流速、温度）的确定性调整和生成具有已知成分（活性惰性比）的颗粒层，所获得的知识还可以扩展到其他应用领域，例如具有改变的烟灰反应性和废气中烟灰浓度的新开发燃料。这提供了一个基本的理解过程中发生的过滤灰和烟灰颗粒。

Cross-flow or wall-flow filters are nowadays a standard component in exhaust gas aftertreatment and reduce particulate emissions from internal combustion engines by removing ash and soot particles. After reaching a critical pressure drop due to the layer formation, the filter is regenerated. The soot particles are oxidized by a continuous (C-NO2) or discontinuous (O2) reaction. This results in a layer break-up. Particulate structures can be detached and transported along the filter channel. In this process, the deposition pattern of the homogenous layer can result in a channel filling. The break-up behavior of the particle layer is a decisive process that depends on the layer composition and the soot reactivity. The aim of the overall project consists of the structured investigation of the relationship be-tween the particle layer of reactive and inert particles and the rearrangement processes (layer break-up – resuspension - transport) of particulate structures during O2- as well as NO2-based regeneration in a model filter channel. In the first project phase, an experimental setup was developed in which the rearrangement processes of resuspended particulate structures during O2-based regeneration can be investigated in a model filter channel. The layer break-up, resuspension and transport of agglomerates is observed over the entire channel length with a high-speed camera and analyzed in terms of resuspension location, agglomerate size and velocity. The developed methods and existing knowledge on the resuspension processes serve as a basis for the objectives de-fined in the second funding period. The goal of the second project phase is therefore to fundamentally investigate the influence of soot reactivity (high reactive vs. low reactive) and soot dispersity as well as the oxidation gas (NO2 vs. O2) on the rearrangement processes in a wall-flow filter. The resulting findings are subsequently used to elucidate the inconsistency from the literature that the resulting deposition patterns in a wall-flow filter are dependent on the oxidation gas used (continuous regeneration (NO2) homogenous layer; discontinuous regeneration (O2) channel filling). The hypothesis is pursued that it is not the oxidation gas but the fundamental particle-technological processes that determine the rearrangement behavior. Through the defined adjustment of process parameters (e.g. flow velocity, temperature) and the generation of particle layers with known composition (reactive inert ratio), the knowledge obtained can also be extended to other fields of application, e.g. newly developed fuels with altered soot reactivities and soot concentrations in the exhaust gas. This provides a fundamental understanding of the processes occurring during the filtration of ash and soot particles.