I’m trying to find data on what happens when a 100 Liter LHe storage dewar experiences a catastrophic failure such as a sudden loss of vacuum. If anyone has any info on this subject, it would be very helpful.
1 Comment
Jonathan Demko
August 1, 2008
Below is some information from a previous study on this subject I worked on:
Lehman and Zahn [1] performed a series of experiments in which outside air was admitted to the vacuum space and the heat transfer was determined from boil-off measurements. The peak values for heat flux were reported to be 0.6 W/cm2 and 3.8 W/cm2 for the insulated and uninsulated cases respectively.
Bartenev et.al. [2] studied the vacuum failure process experimentally by letting helium gas enter the vacuum space at different flow rates. Measured values for peak heat fluxes were 0.95 – 1.93 W/cm2 for superinsulated tests and 0.3 – 0.63 W/cm2 for tests on a dewar with a copper nitrogen shield. This paper showed that the loss of vacuum is less severe for a helium leak than for an air leak.
1. Lehman, W. and Zahn, G, “Safety aspects for LHe transpot containers,” Proceedings of the 7th Annual International Cryogenic Engineering Conference, July 4-7, 1978, London
2. Bartenev, V.D., Datskov, U. A. and Zel’dovich, A.G., “Study of the Processes of Insulation Failure in Helium Cryostats,” CRYOGENICS, Vol.26, May 1986.
1 Comment
Jonathan Demko
August 1, 2008Below is some information from a previous study on this subject I worked on:
Lehman and Zahn [1] performed a series of experiments in which outside air was admitted to the vacuum space and the heat transfer was determined from boil-off measurements. The peak values for heat flux were reported to be 0.6 W/cm2 and 3.8 W/cm2 for the insulated and uninsulated cases respectively.
Bartenev et.al. [2] studied the vacuum failure process experimentally by letting helium gas enter the vacuum space at different flow rates. Measured values for peak heat fluxes were 0.95 – 1.93 W/cm2 for superinsulated tests and 0.3 – 0.63 W/cm2 for tests on a dewar with a copper nitrogen shield. This paper showed that the loss of vacuum is less severe for a helium leak than for an air leak.
1. Lehman, W. and Zahn, G, “Safety aspects for LHe transpot containers,” Proceedings of the 7th Annual International Cryogenic Engineering Conference, July 4-7, 1978, London
2. Bartenev, V.D., Datskov, U. A. and Zel’dovich, A.G., “Study of the Processes of Insulation Failure in Helium Cryostats,” CRYOGENICS, Vol.26, May 1986.