Characterisation of fuel volatile compounds using a new ionic microsensor

International audienceThe "Intermal combustion engines" project of the DIVA (Diagnostique Industriel et Vehicules Avances) [Industrial Diagnostics and Advanced Vehicle) research centre, funded by Region Picardie, aims to develop a real-time system capable of modifying the operating parameters of a diesel engine so as to optimise its pollutant emissions and fuel consumption

Processes of the formation of large unconfined clouds following a massive spillage of liquid hydrogen on the ground

International audienceBecause of hydrogen low volumetric energy content under its gaseous form, transport and storage of liquid hydrogen will certainly play a major role in any future hydrogen economy. One of the obstacles to the expected development use of hydrogen is the poor state of knowledge on explosion risks in the event of an extensive spillage. INERIS set up a large-scale experiment to study the mechanisms of the formation of the gas cloud resulting from such a spillage and the associated mixing process and turbulence effects

Synthese d'oligoisobutenes telecheliques #alpha#-phenol : etude de leur modification par reaction de Mannich en vue de la preparation de produits amphiphiles

CNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Liquefied gas over water : an experimental approach at medium scale to assess gas/water interactions and vapor dispersion

International audienceThis medium-scale experiment allowed validating a measuring setup that permits to assess the behaviour of spilled hazardous liquid/liquefied gases over water. Only the spills of liquefied gas hâve been discussed. It appears that most of the gas vaporization occurs below the water line in the mixing cône produced when the jet pénétrâtes vertically into the water. The température of the emitted vapors at the water surface could be estimated and is shown to be significantly différent from the boiling point in some cases. Thus the dispersing cloud may be less cold and less dense than it would be expected for a cloud vaporizing from a still pool spreading at water surface. The physical process observed in our experiment is not taken into account by common conséquence models, which usually considerthat liquefied gas form a boiling pool at water surface. We thus expect that thèse conséquence models used for safety studies would give conservative results when mixing under water is important, since it can be expected that a lighter cloud would lead to shorter safety distances. Anyway, it is clear from the atmospheric measurements that the cloud is very dense close to the source, even though the ambient flow (turbulence and mean wind velocity) has not shown to be disturbed by the présence of the cold cloud of nitrogen - used as a substitute to LNG in the experiments - at this scale. Otherwise it was verified that the visible part of a cloud and its flammable part do not usually match, as the size of the visible cloud strongly dépends on cloud and air températures and relative humidity. Globally, thèse experiments suggest that release conditions - over water, under water, impinging water surface,...- strongly détermine the actual hazardous areas. Thèse trials can be seen as a first expérimental step towards large-scale experiments of liquefied gas releases at sea needed to assess the behaviour of large hazardous dense clouds over water and to validate accidentai dispersion models

Measuring the flow and the turbulence in a harsh environment using a modified Mc Caffrey gauge

International audienceConsidering that many laboratory measurement techniques devoted to fluid mechanics are difficult to implement in field, especially for combustion and explosions, the present authors developed during the last 2 decades, a special type of Mc Caffrey gauges to measure the flow and the turbulence in those harsh situations (figure 1). Especially a fully embedded version is now under development and the initial work about this innovation is evoked. In this paper, the theory underpinning this technique is presented together with some technical details. Limitations are given and comparisons with reference techniques (hot wire in air jets) are presented

Some fundamental combustion properties of “cryogenic” premixed hydrogen air flames

International audienceBecause of the emergence of the U.E. “green deal” and because of the significant implication of national and regional authorities throughout Europe, the “hydrogen” economy is emerging. And with it, numerous questions and experimentations. One of them, perhaps a key point, is the storage and transport of hydrogen. Liquid hydrogen in cryogenic conditions is a possibility already used in the space industry but under a lot of constrains. What may be acceptable in a well-controlled and restrained domain may not be realistic in a wider application, closer to the public. Safety should be ensured and there is a need for a better knowledge of the flammable and ignition properties of the “cold” hydrogen mixtures following a cryogenic spillage for instance to select adequate ATEX equipment. The purpose of PRESLHY project [4] is to investigate the ignition, fire and explosion characteristics of cryogenic hydrogen spillages and to propose safety engineering methods. The present work is part of it and addresses the measurement of the laminar burning velocity (Sl), flammability limits (FL), minimum ignition energy (MIE)… of hydrogen air mixtures at atmospheric pressure but down to -150°C. To do this, a special burner was designed with details given inside this paper together with the experimental results. It is found that the FL domain is reduced when the temperature drops, that MIE increases slightly and Sl decreases

La sécurité du captage et du stockage du CO2 : un défi pour les industries de l'énergie

National audienceL'accumulation de CO2 dans l'atmosphère induite notamment par les systèmes de production d'énergie qui utilisent des énergies fossiles est largement jugée responsable du réchauffement climatique. Une solution à court et moyen terme a été proposée qui consiste à capter à la source le CO2 dans les fumées de combustion (ou l'extraire du combustible avant combustion), puis à le transporter jusqu'à des zones de stockage géologique. La mise en oeuvre pratique soulève cependant bien des difficultés dont la sécurité. On s'interroge en particulier sur l'effet de fuite massive sur les canalisations de transport, en ayant en tête la tragédie du lac Nyos en Afrique qui a fait 1800 victimes. On présente dans ce document des résultats d'expériences consacrées à la caractérisation de ces fuites. Des moyens d'essais tout à fait originaux ont été mis en place, dont en particulier un réservoir de 2m3 capable de contenir du CO2 en phase dense (comme prévu dans les canalisations de transport), à une pression plus grande que 70 bar, reliée à une canalisation de dépotage permettant des rejets jusqu'à un diamètre d'orifice de 2 pouces. L'installation pourvue de thermocouples, de capteurs de pression et d'un système de pesée a permis de mesurer avec précision les débits massiques et l'état du fluide à l'orifice. Par ailleurs, le nuage formé à l'extérieur a été examiné en détail, dont en particulier la répartition des températures et des concentrations. A fort débit, l'incidence des forces de pesanteur se manifeste de manière nette, ce qui laisse augurer d'une très faible propension à la dispersion

Dynamics of vented hydrogen-air deflagrations

International audienceThe use of hydrogen as an energy carrier is a real perspective for Europe since a number of breakthroughs now enable to envision a deployment at the industrial scale. However some safety issues need to be further addressed but experimental data are still lacking especially about the explosion dynamics in realistic dimensions. A set of hydrogen-air vented explosions were thus performed in two medium scale chambers (1m3 and 10m3). Homogeneous mixtures were used (10% to 30% vol.). The explosion overpressure was measured inside the chamber and outside on the axis of the discharge from the vent. The incidence of the external explosion is clearly seen. All the results in this paper and the predictions from the standards differ greatly meaning that a significant effort is still required. It is the purpose of the French project DIMITRHY to help progressing