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Loads on the 5 K shield

Loads on the 5 K shield. lead to increase on static not the same MLI !. provide thermal intercepts on the many penetrations! couplers x 8 (9) leads cables Shield surface provides surface for thermal strapping with small braids. What is the price to pay @ 2K?.

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Loads on the 5 K shield

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  1. Loads on the 5 K shield lead to increase on static not the same MLI! • provide thermal intercepts • on the many penetrations! • couplers x 8 (9) • leads • cables • Shield surface provides • surface for thermal • strapping with small braids 5K Thermal Shield

  2. What is the price to pay @ 2K? • From Tom Cryo spreadsheet (Feb07) • 2K: 11.4 (1.7 s + 9.7 d) @ 700 W/W • 5K: 15.0 (10.6 s + 4.4 d) @ 200 W/W • 40K: 153.5 (59.2 s + 94.3 d) @ 16 W/W • Sum 14.4 kW plug power for each module (no overcapacity) • If all 5K load goes into 2K “as is” • Plug power increased by 56% • Need to provide same efficient radiation shield for the 2K mass, with at least 10 layers MLI protecting the 2K cold mass • If only radiation flow into 2K (consider factor 2 increase for worse MLI protection) and all conduction intercepted • Plug power increased by 15% • 5K thermalizaton for 3 posts, 8-9 couplers, HOM, leads, cables 5K Thermal Shield

  3. Metric of comparison • Range of effect on plug power (operation cost) is 15% to 55% under rather optimistic conditions given the many penetrations that the module has to the 2 K environment, and located at different positions along the transverse section (top support, side couplers) • Main difference with LHC case • Couplers would not support weight of bulky braids • To be on the lower side we need anyway a 5K cryo circuit for 90% of the conduction heat removal • What is the metric for the comparison of this operating cost hit? • The presence of the 5 K shield is in the module capital cost • if any, still questionable if many thermalization are needed 5K Thermal Shield

  4. 5 K thermal anchors 5K Thermal Shield

  5. Modeling issues • Exchanging info with Norihito to decide simulation comparison metrics • INFN: Type III ANSYS Model • Used for transient cooldown simulations • 2 Shields + HeGRP / No vessels • Non linear material data • Convective time dependent heat load on integrated piping • Used so far to benchmark previous cooldown models • Not all conduction paths included (no couplers yet) • KEK: STF Model 5K Thermal Shield

  6. MLI • CERN data used so far • From r.t. to neglibible temperatures using 30 layers MLI • 1 W/m2 • From 80 K to neglibible temperaturs using 10 layers MLI • 0.05 W/m2 • Taking out 5 K shield how many layers of MLI? • What shielding efficiency? 5K Thermal Shield

  7. From J.Weisend book • From Cry 3 DWGs • 30 MLI sheets in 24 mm, 32 layers/inch • 10 MLI sheets in 9 mm, 28 layers/inch • In literature (“perfect installation of best blanket material”) • 200 mW/m2 from r.t. 30 layers • 20 mW/m2 for 77 K 10 layers • 50 mW/m2 for 77 K 5 layers • Should we use? • 1 W/m2 30lay from r.t. • 50 mW/m2 10lay from 77K • 100 mW/m2 5lay from 77K 5K Thermal Shield

  8. Shield temperature variations • Th is the hot boundary temperature 5K Thermal Shield

  9. Validating model results 5K Thermal Shield

  10. Thermal loads and boundaries 5K Thermal Shield

  11. Exploring max gradient during cooldown 5K Thermal Shield

  12. Gradient on 70 K shield 5K Thermal Shield

  13. Heat flow on 70 K pipe during cooldown 5K Thermal Shield

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