Droplets on Inclined Plates: Local and Global Hysteresis of Pinned Capillary Surfaces

Local contact line pinning prevents droplets from rearranging to minimal global energy, and models for droplets without pinning cannot predict their shape. We show that experiments are much better described by a theory, developed herein, that does account for the constrained contact line motion, using as example droplets on tilted plates. We map out their shapes in suitable phase spaces. For 2D droplets, the critical point of maximum tilt depends on the hysteresis range and Bond number. In 3D, it also depends on the initial width, highlighting the importance of the deposition history.Comment: 5 pages, 5 figures, accepted for publication in Phys. Rev. Let

Size distribution prediction of nanoparticle agglomerates in a fluidized bed

Nanoparticles have acquired considerable attention from academia and industry due to their unique properties arising from the large surface area to volume ratio. A promising method to process these particles is fluidization. Furthermore, it is worth knowing that nanoparticles fluidize as clusters called agglomerates, formed by the relatively strong adhesion forces among the individual particles (1). These agglomerates are large, highly porous fractal structures; thus, easy to access but extremely fragile. During fluidization, agglomerates move, collide, break, reform, deform, and combine, which make them suitable for a wide range of applications. Nanopowders can fluidize with bubbles or uniformly, which show different dynamics that might affect the morphology of the fluidized agglomerates. In order to better understand the dynamic behaviour of the system, it is crucial to know the agglomerate size distribution within the fluidized bed. Therefore, we developed a model based on a simple force balance to predict the agglomerate size distribution, which enables the optimization of processing methods. Please click Additional Files below to see the full abstract

Heterogeneously Catalyzed Continuous-Flow Hydrogenation Using Segmented Flow in Capillary Columns

Segmented flow in standard GC capillary columns, with a heterogeneous Pd catalyst on the walls, gave rapid information about catalytic processes in them. The residence time and conversion was monitored visually, greatly simplifying bench-scale optimization. Examples show the benefits of the elimination of pore diffusion and axial dispersion. Further, we demonstrated how to quickly identify deactivating species in multistep synthesis without intermediate workup

Two-phase segmented flow in capillaries and monolith reactors

Monolith reactors are attracting more and more attention as alternatives for both threephase slurry reactors [1-3] and trickle-bed reactors [4,5]. From a fluid mechanical point of view, the operating mode depends on the size of the straight parallel channels. In large channels the fluid trickles downwards along the channel walls and the gas travels through the channel in the channel core. In smaller channels, the dominant flow pattern is a segmented slug flow or bubble-train flow of alternating bubbles and slugs, where the bubbles span all but the complete channel cross-section. In the beginning of this chapter, criteria to predict the different multiphase flow regimes are briefly reviewed, and the remainder of the chapter deals with the segmented flow pattern. For the trickle-flow or film-flow pattern, the interested reader is referred to Chapter 13