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Eingeladener Vortrag
- nein (34)
100 mm of PUR-foam give satisfying results in terms of
thermal properties. The non-pressure testing methods gives reliable and repeatable results. Bending modulus of laminates does not change until the first damage occurs. After that, the bending modulus decreases by 50 % but max. stress is still higher than at room temperature.
Figure 10 illustrates the theoretical results from the simplified model considered, together with the experimental data. These results and measurements are presented one next to the other, in order to facilitate the validity analysis of the proposed simulation methodology.
These results illustrate that the trends are comparable for both sets of data, that is, a similar range is obtained for all of the variables reported. A lower pressure is generated in chamber 5, which is attributed to the shorter length of this chamber. However, such increase in pressure does not correspond exactly to the difference of lengths, as the ratio of lengths would cause a differential pressure of 2.3/1.23 = 1.86, while the ratio of average pressures is on the order of 2. That is, there is an incremental, which is associated to the maximum height attained by the fluid in the chamber. The major difference between both sets of data, the experimental and theoretical, is that the theoretical do not include much of the noise and random oscillations reported in the experimental data. Such noise, however, is of very low amplitude, in comparison with the maximum values attained. The practical applications of these results could be in the area of chamber design, so that the effects of the length of the chambers be taken into account. That is, such greater lengths for the fluid in the chamber would involve larger pressures and consequently, greater stresses. However, the analysis should include an overall perspective, that is, the shortening of the chambers would imply an increase in the number of chambers, for a certain total payload, and the superposition effect of pressures, should be considered. On the other hand, the analysis could be extended to characterize the effects of the distribution of the lengths of the different chambers along the axis of the tanker, as the different resulting forces could have different effects on the pitch response of the road tanker.
The importance of tanks for storing cryogenic fluids in the energy industry is increasing because of ongoing political conflicts and the implementation of more environmentally friendly energy sources. Key representatives for the application of cryogenic tanks are natural gas in the form of Liquefied Natural Gas (LNG) and hydrogen, e. g. in the form of Liquefied Hydrogen (LH2), for which significantly higher transport capacities can be achieved with the same transport volume using cryogenic storages than with storages based solely on overpressure.
What applies to all cryogenic transported fluids in common is their condition that must be maintained. Hence heat flows into the preserved fluid must be minimized. Thermal super Insulations (TSI) based on e. g. multilayer insulations (MLI), perlites, and vacuum are utilized for this purpose and have already proven themselves in similar applications. However, for the use of tanks for cryogenic fluids in the transport sector, there is insufficient knowledge regarding the course and consequences of incidents, which is due to the still short period of use and the few documented incidents, hence few investigations carried out in this field. Typical scenarios in the transport sector represent car accidents with collisions, fires, and their combination, which are associated with extraordinary loads on the tank.
The focus of this study is to investigate the behavior of TSI as a result of their thermal exposure to a heat source representing a fire. It is worth mentioning that this could lead to an increase of the heat flux into a tank by several orders of magnitude, and to permanent damage of the TSI, ultimately rapid release of flammable gas as well as a Boiling Liquide Expanding Vapour Explosion (BLEVE). For this purpose, a high temperature thermal vacuum chamber (HTTVC) has been developed that allows thermal loading of MLI or perlites in a vacuum and simultaneous measurement of heat flow through this TSI. The HTTVC is designed to represent realistic insulation conditions and to withstand thermal loads from typical design fires.
The HTTVC was applied to investigate TSI based on MLI and vacuum. It is shown that the thermal stress caused permanent damage to the TSI, with shrinkage, phase change, pyrolysis, and condensation being significant damage mechanisms. The results are relevant for the evaluation of accident scenarios and can thus contribute to the improvement of TSI and the development of emergency measures for the protection of persons and infrastructures.
In-service inspection Atucha
(2011)
Gefahrguttanks werden primär gegen betriebliche Belastungen dimensioniert. Unfallbelastungen spielen hierbei keine Rolle. In der Vergangenheit gab es immer wieder einige katastrophale Unfälle, die nicht nur materielle Schäden zur Folge hatten sondern bei denen auch Todesopfer zu beklagen waren. Zur Ermittlung möglicher Sicherheitsreserven werden Untersuchungen zum Abtrag auslegungsüberschreitender Belastungen durchgeführt. Mit dem Grenzlasttragverfahren steht ein leistungsfähiges Analysewerkzeug zur Verfügung, mit dem nichtlineare Beanspruchungsszenarien bewertet werden können. Der Vergleich der numerischen mit den experimentellen Ergebnissen zeigt dies eindeutig.
Transport safety depends in great extent of what happens to the cargo once the carrying vehicle derails or rollovers. The exposure of tanks to direct fire is a condition that potentially involves catastrophic consequences. Studying the behavior of the contained fluid under these drastic circumstances, is critical to develop methods and techniques to mitigate the serious consequences of many mishaps. In this paper, the experimental potentials of a Particle Image Velocimetry data acquisition system are described, for providing experimental data that could be used to calibrate mathematical models. As an example of the situations that need to be modelled, an experiment is described concerning the effect of the boundary conditions and protecting devices, on the rate of variation of pressure and temperature of the fluid in a tank exposed to a direct fire. In this regard, the results emphasize the importance of equipping the vessels with both thermal insulation and safety valves.