Etude expérimentale de la faisabilité de piégeage des gaz rares par des matériaux poreux innovants

National audienc

Etude expérimentale de la faisabilité de piégeage des gaz rares par des matériaux poreux innovants

National audienc

Filtration tests of gaseous ruthenium tetroxide by sand bed and metallic filters

International audienceThis work presents laboratory tests on gaseous RuO4 filtration carried out at IRSN in Cadarache. The objective is to determine if gaseous ruthenium tetroxide can be trapped by metallic filter and sand bed filter, both elements being used in filtered containment venting systems implemented on French pressurized water reactors. The results show no ruthenium tetroxide trapping by physical or chemical adsorption but certain retention is observed resulting from its thermal decomposition into solid ruthenium dioxide. A thermodynamic analysis of the system tends to confirm this conclusion. Chemical stability of RuO4(g) has to be considered as it strongly impacts potential filtration and so potential releases. © 2019, Akadémiai Kiadó, Budapest, Hungary

Improved CFD transport and boundary conditions models for low-inertia particles

This paper presents a simple aerosol transport model together with specific boundary conditions, which can be easily implemented in a CFD code in order to calculate particulate concentrations at any point in a dilute gas-particle flow. The low-inertia of the particles considered (aerodynamic diameter less than 50 μm) enables a simplified Eulerian model to be proposed ("diffusion-inertia"), which consists of a single transport equation of aerosol concentration considering sedimentation, deviation from fluid streamlines and migration effects. Specific study of deposition has made it possible to develop a new boundary condition approach at smooth walls based on semi-empirical deposition laws, which determines the particle flux towards the wall in the boundary layer for any deposition regime and any surface orientation from the computed CFD variables. These transport and deposition models can be used for a very wide range of geometries (from elementary devices to rooms of various volumes), in industrial applications dealing with particulate contamination. In this paper, the models are validated for simple geometries, by comparing published data to the CFD results. © 2010 Elsevier Ltd

Etude de matériaux poreux de type Metal-Organic Framework pour le piégeage du ruthénium

International audienc

Capture of gazeous radionuclides in porous Metal-Organic Frameworks

International audienc

Measurement and modeling of pressure drop of HEPA filters clogged with ultrafine particles

International audienc

Influence of Pleat Deformation on Pressure Drop for a High-Efficiency Particulate Air Filter: A Small-Scale Experimental Approach

International audienceFor industrial or domestic applications, the wide range of use of pleated filters makes the understanding of their airflow behavior a major issue for designer and users. In all industrial installations dealing with radioactive matter, the containment of pollutants must be ensured. High-efficiency particulate air (HEPA) filters are used as the last purification stage before the air is rejected in the environment. These filters can be used either alone, in the case of nonsensible installation, or coupled with other filtration devices disposer before it where contamination level could be important. The prediction of their pressure drop is very important in nuclear safety to be able to anticipate any dysfunction or rupture of these devices. It has been observed that geometry of the medium has an influence on the pressure drop of a pleated filter. In the case of HEPA filters, no convincing explanation has been brought to explain their airflow behavior. The pressure drop evolution of the filtre during the clogging remains difficult to explain by assuming constant pleat geometry. Some studies show that deformation occurs during the filter use, which could induce an increaseof the available volume in the pleat and a reduction of the efficient filtration surface. The increase in computation capacity introduces nowadays the possibility to perform complex simulation, taking into account the effect of fluids on sensible devices. This can be the case for simple structural analysis or for more complex analysis such as vibration induced by gas or fluid flow. It is mostly applied to avoid breaking or deformation of safety devices,and this can also be applied to anticipate the fluid behavior of some special devices such as filters. In classical filtration application, properties of the filter are coupled with particle deposition (e.g., changes in geometry and permeability depend on the thickness of the deposit). The studies concerning mechanical properties of filters are mainly perfore for liquid filtration and clean filters. For pleated filters, the complexity of this kind of analysisremains the modification of the link between geometry, pressure drop, mechanical strength, and particle transport and accumulation inside the pleat. As a first approach, it has been chosen to combine an experimental and a numerical approach to improve the understanding of filter behavior. In this paper, the pleat deformation will be investigated using a direct nonintrusive laser measurement performed on a single pleat experiment.The rate of filtration surface lost will be estimated using these data and taken into account to evaluate the pressure drop against the filtration velocity. Results obtained show that the pleat deformation is an important parameter, which influences the geometry of the pleat