Aleksander Kopczyński Test stand for determination of the heat flux to the cold elements of cryogenic systems in case of the vacuum vessel failure Aleksander Kopczyński Ziemowit Malecha Jarosław Poliński ICEC27-ICMC 2018 Oxford, 4.09.2018
Scope Problem’s background Wroclaw University of Science and Technology test setup description Experiment methodology discussion Conclusions
Problem’s background The cryogenic vessels or fluid distribution circuits need to be protected by safety equipment against excessive pressure caused by intensive heat inflow to this elements Example of Cryogenic Distribution System (ESS) – process lines safety equipment
Problem’s background One of the heat inflow source to be considered in the safety equipment sizing is the incidental ventilation of the vacuum vessel with atmospheric air. 300 K 20-90 K 4.2 K
Problem’s background The heat flux with atmospheric air inflow to helium temperature elements has been already experimentally determined as 3.7 – 5.0 kW/m2 [1,2,3], The thermal shields are covered from external side with 30-40 layers of MLI. The heat flux through the MLI side can be expected as 0.25 kW/m2 [4]. QAir-He= 3.7-5 kW/m2 QAir-TS_Bare=??? QAir-TS_MLI=0.25 kW/m2
Problem’s background TS temperature Gas convection Condensation Air_Liq TS temperature Condensation Air_III Solid deposition
Problem’s background Schematic temperature profile during vacuum degradation failure (based on [7]), where: : I- vacuum chamber section; II- liquid deposit section; III- solid deposit section; IV- cold wall section; V- liquid cryogen section
Wroclaw University of Science and Technology cryostat Chosen physical properties of possible gases selected for the experiment Boiling temperature, K Triple point temperature, K Heat of evaporation, kJ/kg Heat of melting, kJ/kg Helium 4.23 - 20.8 Air 78.9 59.8 205.5 - Nitrogen 77.3 63.3 199 25.8 Argon 83.8 87.3 163 29.6
Wroclaw University of Science and Technology cryostat
Wroclaw University of Science and Technology cryostat Vacuum vessel Horizontal length 3600 mm Horizontal diameter 320 mm Vertical length 1900 mm Vertical diameter 506 mm Volume 530 l
Wroclaw University of Science and Technology cryostat Vacuum vessel Horizontal length 3600 mm Horizontal diameter 320 mm Vertical length 1900 mm Vertical diameter 506 mm Volume 530 l Nitrogen tank Volume 13 l
Wroclaw University of Science and Technology cryostat Cold vessel Horizontal length 3350 mm Horizontal diameter 115 mm Vertical length 820 mm Vertical diameter 172 mm Heat transfer area 1.90 m2
Wroclaw University of Science and Technology cryostat
Wroclaw University of Science and Technology cryostat
Helium vessel heat transfer measurement Isochoric change of state (8) Isobaric change of state (9)
Final remarks
Thank you for the attention!
References Lehmann, W., Zahn , G., “Safety Aspects for LHe Cryostats and LHe Transport Containers” Proceedings of International Cryogenic Engineering Conference 7, IPC Science and Technology Press, London, 1978, pp. 569-579. Will Francis, Mike Tupper, Stephen Harrison, Conformable tile method of applying CRYOCOAT™ UL79 insulation to cryogenic tanks. Harrison, S. M., “Loss of Vacuum Experiments on a Superfluid Helium Vessel” in IEEE Transactions on Applied Superconductivity, IEEE, 2002, pp. 1343-1346 G.F. Xie, X.D. Li, R.S. Wang , Study on the heat transfer of high-vacuum-multilayer-insulation tank after sudden, catastrophic loss of insulating vacuum, Cryogenics 50 (2010) 682–687 M. Chorowski, J. Fydrych, Z. Modlinski, J. Polinski, L. Tavian, J. Wach, Upgrade on risk analysis following the 080919 incident in the LHC sector 3-4, CERN/ATS/Note/2010/033 (TECH), 2010-07-01 Heidt C., Grohmann S., Süßer, M. Modeling the Pressure Increase in Liquid Helium Cryostats after Failure of the Insulating Vacuum, 2014 AIP Conf. Proc. 1573,1574-1580 Zoller C., Experimental Investigation and Modelling of Incidents in Liquid Helium Cryostats, PhD Thesis, Karlsruhe Institute of Technology, Karlsruhe