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Second Meeting of the Material Budget & Engineering Working Group. feasibility of CO2 cooling with existing CMS pipework. Re-use cooling pipes. Cooling pipes are installed as bottom layer on the vac-tank. Covered by a vast amount of ECAL and Tracker cables.
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Second Meeting of the Material Budget & Engineering Working Group feasibility of CO2 cooling with existing CMS pipework Hans Postema (CERN)
Re-use cooling pipes • Cooling pipes are installed as bottom layer on the vac-tank. • Covered by a vast amount of ECAL and Tracker cables. • Covered by a vast amount of Tracker optical fibres. • Re-installation of pipes will require an extremely long shutdown. Hans Postema (CERN)
YB0 with cables Hans Postema (CERN)
Inside the Vac-tank Hans Postema (CERN)
YB0 and PP1 view Hans Postema (CERN)
YB0, tower, balcony Hans Postema (CERN)
PP1 to tower routing Hans Postema (CERN)
All routes, Z+ view Hans Postema (CERN)
Top view UX cavern Hans Postema (CERN)
Summary of tubes • Between Tracker and PP1 3 m of tube with ID 10 mm, can easily be replaced • Between PP1 and Tower, 20 m of tube with ID 12 mm • Between Tower and Cooling station 20-40 m of tube with ID 14 mm • All tubes are soft copper with 1 mm wall thickness • Tubes can run either 10 m up or down with respect to the Tracker Hans Postema (CERN)
CMS ladder dimensions 1mm ID Tube Q = 40 Watt Tube length = 2.5 meter 1 CMS ladder : 1.25 meter length Cooling
CMS, use of existing tubes • CMS pipes = 14mmID • 18kW =>1 liquid line & 6 vapor lines • 1 loop assembly = 7 tubes • 6 loop assemblies = 42 tubes for 108 kW • 450 ladders per loop assembly • 3150 ladders in total • Shut-down and start-up difficult due to low allowed pressure of Cu-tubing 12.7bar = - 33’C 10 m static height: dP=1bar~2’C dT 120 g/s, 18kW 6 tubes 13.9bar Dcooling=1mmID Q=40W TCO2=-30’C MF= 0.26 g/s dP= 600 mbar dP@50m=150mbar~0.3’C dT 450x Liquid CO2 P=17.9 bar T=-38’C 14.5bar 1 tube 17.9bar 17.7bar Dcapillary=0.5mmID x 5m dP=3.2bar 120 g/s liquid = 200mbar
Pressures • Elastic limit of soft copper 16 mm pipe corresponds to about 70 bar. • CO2 boiling point -20 C at 20 bar, thus moderate pressure during operation. • At +25 C, CO2 boils at 65 bar, this requires further investigation into a system with low pressure startup capability. Hans Postema (CERN)