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Accidental gas explosions represent an ever-present hazard for process industries handling flammable gases and liquids. There is also an increasing danger of vandals and terrorists using improvised explosive devices in industrial areas neighboring highly populated residential areas. The consecutive pressure wave generation and propagation can result in unacceptable risk exposition of citizens and infrastructures. Therefore, it is necessary to define design rules of protective barriers mitigating the effect of blast wave.

Gaseous explosion models generally assume the gas mixture to be uniform. However, in a real explosion, the vapor cloud may not be homogeneous, and repartitioning of the reactivity inside the cloud can be subject to wide spatial variations. In this work, experimental tests were run to study the flame propagation and acceleration in nonuniform mixtures. Experiments were performed in a long vertical confined tube with a square cross section, composed of four equal sections. A gate valve separated the tube into two parts, and the composition of the gases was different on each side of the valve. The opening of the valve permitted the mixing of gases by molecular diffusion. For nonuniform mixtures, a mode of propagation identical to that seen in uniform mixtures was observed; however, a third phase of propagation was found, in which the flame velocity increased strongly. This increase occurred with higher hydrogen concentration in an upward-propagating flame. A concentration gradient can appreciably modify the trajectory and acceleration of a flame. Here, however, the incidence of pressure effects remained modest, since the combustion was confined and the final pressure depended mainly on the quantity of reactants available. © 2009 American Institute of Chemical Engineers Process Saf Prog, 2009.

This paper was presented at the Seventh International Conference of Hydrogen Safety (ICHS 2017) in Hamburg on 11-13 September 2017. The paper summarises the results from a blind-prediction study for models developed for estimating the consequences of vented hydrogen deflagrations. The work is part of the project Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations (HySEA). The scenarios selected for the blind-prediction entailed vented explosions with homogeneous hydrogen-air mixtures in a 20-foot ISO container. The test program included two configurations and six experiments, i.e. three repeated tests for each scenario. The comparison between experimental results and model predictions reveals reasonable agreement for some of the models, and significant discrepancies for others. It is foreseen that the first blind-prediction study in the HySEA project will motivate developers to improve their models, and to update guidelines for users of the models. The paper is a deliverable from the project “Improving hydrogen safety for energy applications through pre-normative research on vented deflagrations”, or HySEA (www.hysea.eu), which receives funding from the Fuel Cells and Hydrogen Joint Undertaking (FCH JU) under grant agreement no. 671461. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme and United Kingdom, Italy, Belgium and Norway.

The authors report three cases of psychotic complications of cardiac surgery. A review is made from literature and an inventory of psychological and organic factors implicated in this pathology. These complications are still frequent (up to 50% for Braceland, and 70% for Rabiner and al.). For Blacher there is an almost universal "psychosis" in by-pass surgery and frequent "hidden psychosis" (they are ignored and denied both by the staff and the patient). They are caused by the emotional stress, intensive care unit syndrome, or personal vulnerability. The symbolism of the heart and the personality of the cardiac patient are also in cause. Neurologic accidents, hypoxy, embolisms, are now less frequent. The collaboration of a psychiatrist with the cardiologic staff is mandatory. With this collaboration not only psychiatric complications but also somatic morbidity and mortality would be reduced.