Cryotank
A cryotank is a cryogenic storage facility. It is particularly characterized by good insulation without cooling.
Cryogenic tanks for gases are used, for example, as fuel tanks for motor vehicles that store fuels such as liquefied natural gas (LNG) or liquid hydrogen (LH 2 ). LNG can be stored in the vehicle tank at low pressures (2 bar) but at low temperatures (−160 ° C), LH 2 is stored at −253 ° C. An LH 2 cryotank was used in the BMW Hydrogen 7 , among others .
Since the cryotank in the vehicle does not have its own cooling system, special insulation is required. In addition, the pressure has to be limited, since the cryotank is normally not designed for the pressure at which the liquefied content has been converted back into gas (boil-off gas). In the case of hydrogen vehicle tanks, a loss of around 2% per day is assumed (according to the 2015 state of the art) if the pressure increase is not reduced by extracting gas for the engine.
Some design restrictions for cryotanks in vehicles can be found in the patent literature, for example, only boil-off gas should be withdrawn in order to minimize the cooling effect and the loss; it is withdrawn at the top point, which is additionally protected by separating plates, thus also at Cornering only gaseous fuel is taken. Special fittings ensure that the tank emits gas in almost every position and not liquid.
Whether a cryotank is required to store a liquefied gas, or whether it can be kept liquid under pressure alone, depends on the critical temperature of the gas in question. Thus require liquid propane - butane -mixtures (critical temperature at least 96 ° C), as the fuel under the designations LPG or LPG known under normal environmental conditions, only a pressure accumulator , but no cryotank.
Another application of cryotanks is the cryogenic preservation of biosamples in cryobanks .
Web links
Individual evidence
- ↑ a b Richard van Basshuysen, Fred Schäfer (Ed.), “ Handbuch Internal Combustion Engine” , 7th edition, Springer Fachmedien Wiesbaden 2015, ISBN 978-3-658-04677-4 , Section 22.1.2.3 “ Alternative gasoline ”.
- ↑ a b Patent DE 102004016135 from BMW AG “ Cryogenic tank, especially for storing hydrogen in a motor vehicle ” from October 20, 2005.
- ↑ Patent DE 10152631A “ Safety valve extraction line for a storage container for cryogenic medium ” from BMW AG from October 25, 2001.
- ↑ contribution " cryopreservation of living biological samples - Kryotechnologieplattform for Biotechnology and Medicine " Biomedical Günter R. Fuhr, Fraunhofer Institute of Technology, in St. Ingbert in " Bionics - Current research in natural sciences, engineering and the humanities ", Springer New York 2005, ISBN 3-540-21890-4 .