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- 2011 (9) (entfernen)
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Eingeladener Vortrag
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COMSOL Multiphysics® was used as a tool for the better understanding of the evolution of flow patterns during the induced ignition of gases. A simplified model was developed for the scope, by coupling the weakly compressible Navier Stokes module and the convection and conduction module. The current paper presents the results of the performed simulations.
Beim begehrten Kunststoff Teflon führt kein Weg an einem komplexen Herstellungsprozess vorbei, der aufgrund der besonderen Eigenschaften des Ausgangsstoffes spezieller sicherheitstechnischer Anforderungen bedarf.
Comsol Multiphysics unterstützte Wissenschaftler in der Auslegung der Produktionsanlagen bei der Identifizierung von Gefahrenquellen.
The temperature and gas concentrations in a
newly established pine-wood debris pile of 20 m × 15 m ×
6 m in dimensions (approximately 400 tons of fresh weight
material) were monitored for 150 days. Temperature was
measured at ten different positions within the pile, while
concentrations of CO2, O2, CO and CH4 were taken at four
different representative locations. The pile was characterized
by a strong temperature increase within the first 10–
12 days of storage. Results of the gas analysis in this period
suggest that the temperature increase was caused by microbial
processes. In particular, reduced oxygen concentration
and almost complete absence of methane indicate mainly
aerobic respiration processes. Effects of weather conditions
on the temperature/gas distribution and time evolution are
also discussed in the paper.
Prevention of the explosion of acetylene cylinders involved in fire: experiments and simulations
(2011)
In order to assess the effectiveness of water cooling of acetylene cylinders involved in fire, a total of 13 bonfire tests with 8.9-, 10
and 50-l-cylinders were performed. During the experiments the pressure
in the cylinder and the temperature at different locations within the porous material and on the Shell surface as well as the flame temperature were measured. Overall 8 burst tests were performed, in order to determine the times to explosion for the cylinders. Cylinders failed not later than 15 minutes from the ignition of the bonfire, often with generation of a fireball. During the other 5 tests, the fire was extinguished before the expected burst and the cylinder was cooled with water. In 2 of the 5 extinction experiments, the explosion of the cylinder could be prevented. Noticeably, in one case the on-set of the decomposition of acetylene had already been observed, before the cooling was started. In spite of that, the cooling was still effective. The interpretation of the current results and of the data from previous tests with 40-l-cylinder suggests that single acetylene cylinders involved in fire might be saved by cooling, if their pressure does not exceed a value of about 45 bara. The recorded values of pressure and temperature were used to develop and validate a mathematical model for the prediction of the heat transfer in acetylene cylinders during the exposure to fire and the afterward cooling. The predictions agreed well with the experimental results.