Is there anyone who has information about the heat flux in case of vacuum loss on cryogenic surfaces?
2 Comments
Bernd Gottschlich
August 1, 2008
Known is the paper of W. Lehmann at ICEC 7 1978 of measurements at Forschungszentrum Karlsruhe and the report of Dr. Schrawer in Gas Aktuell 22 – 1981 regarding Measurements of Messer Griesheim.
Unfortunately, the heat flux valves for not superinsulated wetted LHe-surfaces differ about factor 10 in both experiments. In particular for me, it would be interesting to get heat flux valves for shielded transfer lines at 4.5K and also at higher temperatures (40-80K). The problem for long transfer lines is the max. distance between safety valves, which will be necessary because of the pressure drop on the way to the safety valve.
The calculation with too high heat flux valves leads to a reasonable number of safety valves, especially for small tube diameters. If someone is interested in the above mentioned reports, I can send them to him/her by fax.
* Loss of Cavity Vacuum Experiment at CEBAF by M. Wiseman, et al., Adv. Cryo. Eng. Vol. 39A, Plenum Press NY 1994, pp. 997 for work on bare 2 and 4K surfaces. and
* CEBAF Cryounit Loss of Vacuum Experiment by M. Wiseman, et al., App. Cryo. Tech., Vol. 10, Plenum Press NY 1990, pp. 287 for work on an MLI insulated 4K surface.
You should also look to the Compressed Gas Association pamphlets. For example, Pressure Relief Device Standards—Part 3—Stationary Storage Containers for Compressed Gases, CGA S-1.3.
There is also an interesting graph on pg. 270 of Technology of Liquid Helium, NBS Monograph 111, edited by R. H. Kropschot, et. al. that would be helpful.
2 Comments
Bernd Gottschlich
August 1, 2008Known is the paper of W. Lehmann at ICEC 7 1978 of measurements at Forschungszentrum Karlsruhe and the report of Dr. Schrawer in Gas Aktuell 22 – 1981 regarding Measurements of Messer Griesheim.
Unfortunately, the heat flux valves for not superinsulated wetted LHe-surfaces differ about factor 10 in both experiments. In particular for me, it would be interesting to get heat flux valves for shielded transfer lines at 4.5K and also at higher temperatures (40-80K). The problem for long transfer lines is the max. distance between safety valves, which will be necessary because of the pressure drop on the way to the safety valve.
The calculation with too high heat flux valves leads to a reasonable number of safety valves, especially for small tube diameters. If someone is interested in the above mentioned reports, I can send them to him/her by fax.
Pat Kelley
August 1, 2008Try the following references:
* Loss of Cavity Vacuum Experiment at CEBAF by M. Wiseman, et al., Adv. Cryo. Eng. Vol. 39A, Plenum Press NY 1994, pp. 997 for work on bare 2 and 4K surfaces. and
* CEBAF Cryounit Loss of Vacuum Experiment by M. Wiseman, et al., App. Cryo. Tech., Vol. 10, Plenum Press NY 1990, pp. 287 for work on an MLI insulated 4K surface.
You should also look to the Compressed Gas Association pamphlets. For example, Pressure Relief Device Standards—Part 3—Stationary Storage Containers for Compressed Gases, CGA S-1.3.
There is also an interesting graph on pg. 270 of Technology of Liquid Helium, NBS Monograph 111, edited by R. H. Kropschot, et. al. that would be helpful.