CFD modeling of droplet permeability in fluidized beds

The deposition of droplets of size [5–22] μm on the surface of particles in a gas–solid fluidized bed has been investigated employing a one-way coupled CFD-DEM modeling. In this approach the gas phase is solved as a continuum and the free-droplets are solved as Lagrangian objects, while solid particles are assumed to be stationary and act as an obstacle for the fluid flow. In this way, it was possible to calculate the deposition factor, defined as the ratio of droplets deposited on the surface of the particles to the number of droplets injected into the domain as a function of the droplet Stokes number and particle Reynolds number. An empirical correlation was developed that describes the deposition factor as a function of the operating conditions, which is valid for the inertial regime where effects of Brownian motion can be neglected. The final goal of this investigation is to employ the developed correlation in a larger scale CFD-DEM model describing a polymerization fluidized bed reactor operated in condensed mode, i.e. by injecting liquid into the gas–solid suspension through the gas distributor plate or via nozzles in order to improve the heat management. In this kind of modeling the free-droplets phase is described as a continuum and the deposition rate of droplets determines the amount of liquid on the particle surface, which affects for the hydrodynamic (i.e. formation of liquid bridges between particles) and thermal behavior (i.e. liquid evaporation, kinetic and subsequent cooling effect) of the system

Atrial fibrillation history impact on catheter ablation outcome. Findings from the ESC-EHRA Atrial Fibrillation Ablation Long-Term Registry

Background Atrial fibrillation (AF) promotes atrial remodeling that in turn promotes AF perpetuation. The aim of our study is to investigate the impact of AF history length on 1-year outcome of AF catheter ablation in a cohort of patients enrolled in the Atrial Fibrillation Ablation Registry. Methods We described the real-life clinical epidemiology, therapeutic strategies, and the short- and mid-term outcomes of 1948 patients (71.9% with paroxysmal AF) undergoing AF ablation procedures, stratified according to AF history duration (= 2 years). Results The mean AF history duration was 46.2 +/- 57.4 months, 592 patients had an AF history duration = 2 years (mean 75.5 +/- 63.5 months) (P = 2 years (34.0%) (P = 0.037). AF history duration >= 2 years, overall ablation procedure duration, hypertension, and chronic kidney disease were all predictors of recurrences after the blanking period. Conclusions In this multicenter registry, performing catheter ablation in patients with an AF history >= 2 years was associated with higher rates of AF recurrences at 1 year. Since cumulative time in AF in not necessarily equivalent to AF history, its role remains to be clarified.Cardiolog

ALICE upgrades during the LHC Long Shutdown 2

International audienceA Large Ion Collider Experiment (ALICE) has been conceived and constructed as a heavy-ion experiment at the LHC. During LHC Runs 1 and 2, it has produced a wide range of physics results using all collision systems available at the LHC. In order to best exploit new physics opportunities opening up with the upgraded LHC and new detector technologies, the experiment has undergone a major upgrade during the LHC Long Shutdown 2 (2019–2022). This comprises the move to continuous readout, the complete overhaul of core detectors, as well as a new online event processing farm with a redesigned online-offline software framework. These improvements will allow to record Pb-Pb collisions at rates up to 50 kHz, while ensuring sensitivity for signals without a triggerable signature