a b s t r a c tSafety studies for production and use of hydrogen reveal the importance of accurate prediction of the overpressure effects generated by delayed explosions of accidental high pressure hydrogen releases. Analysis of previous experimental work demonstrates the lack of measurements of turbulent intensities and lengthscales in the flammable envelope as well as the scarceness of accurate experimental data for explosion overpressures and flame speeds. AIR LIQUIDE, AREVA STOCKAGE ENERGIE and INERIS join in a collaborative project to study un-ignited and ignited high pressure releases of hydrogen.The purpose of this work is to map hydrogen flammable envelopes in terms of concentration, velocity and turbulence, and to characterize the flame behaviour and the associated overpressure. These experimental results (dispersion and explosion) are also compared with blind FLACS modelling.
The process of carbonitriding is similar to the process of carburization yet with additional ammonia to increase the hardness of the metal surface. Carbonitriding is performed at approximately 850°C-880°C, which is lower compare to carburizing and low pressure (10-50 mbar). The process consists of two stages: decomposition of ammonia and diffusion of "activated nitrogen", and decomposition of acetylene and diffusion of carbon. The decomposition of acetylene is a very complex phenomenon, depending on the temperature, pressure and residence time (the time of presence of acetylene in a furnace). Different reaction products form: small molecules (H 2 , CH 4 , C 2 H 4 , C 6 H 6 , etc.), fine-crystalline graphite (the one that diffuses into the metal surface), polycyclic aromatic hydrocarbons (PAHs), soot etc. The current investigation is based on detailed kinetic modeling (using Chemkin 17.1) of the acetylene decomposition in the atmosphere of a reactor. For this modeling three different comprehensive mechanisms from the literature are considered: the mechanism of K. Norinaga (including 227 species, 827 reactions), the mechanism of T. Bensabath (including 364 species, 1245 reactions) and the mechanism of C. Saggese (including 350 species, more than 10,000 reactions). Comparison of simulation results with experimental data from the literature showed good agreement, demonstrating their applicability for modeling of industrial process. A parametric study suggests the best parameters for acetylene decomposition in a furnace.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.