25/3/2009Detector Cooling Project Meeting I1 Running consolidation activities of ALICE Detector Cooling Systems A.Tauro

25/3/2009Detector Cooling Project Meeting I2 ALICE cooling performance The ALICE cooling systems have been widely commissioned over the last two years. Extensive knowledge of the systems was gained at all levels: EN-CV, ALICE TC and subdetectors communities Some systems have undertaken (major) modifications, discussed and agreed by the ALICE TC and EN-CV The operational performances of the ALICE cooling systems are generally in line with the specifications We want anyway to profit of this long shutdown to fix some 2 nd order importance problems The collaboration with EN-CV is for us vital. One proof is the (almost) daily interaction with Jose and the invaluable feedback from Michele’s group

25/3/2009Detector Cooling Project Meeting I3 Problem observed: bubbling effect In certain places the water pressure is < 50 mbar This produces bubbles inside the pipes, and an audible noise in the range of some Hz Potentially dangerous: increases the flow resistance due to bi-phase liquid Increasing the tank pressure solves the problem but then makes the startup impossible (need to kick up the pressure in order to get rid of the air in the pipe) Solution: switch from startup tank pressure (e.g. 350 mbar) to running mode (e.g. 500 mbar) time

25/3/2009Detector Cooling Project Meeting I4 standby Pump down to 350 mbar ~ 10’ run Return to 500 mbar Outlet & Reservoir PressureLoop Pressures (A-side) stop & initiate startup start circulation pump L.Musa Solution adopted 2008 (TPC) Time needed to pump down to 350 mbar: 10’ Low vacuum capacity during run - tank is at ‘high’ pressure

25/3/2009Detector Cooling Project Meeting I5 Upgrade 2009 (TPC and TRD) New vacuum pump –Minimize stand-by time before startup Back-pressure valve before the tank –Fast variation of the return pressure in case of leak (valve opens) Increase thermal uniformity covers/bus-bars (TPC) –Increase flow and heater power of a factor >3 (4 loops) –Re-route cooling lines close to detector (reduce siphons) Optimize res-rods cooling (TPC) –Inherently small flow, susceptible to environment (cavern temperature, nearby heated, not well insulated lines) –New loop and heat exchangers

25/3/2009Detector Cooling Project Meeting I6 RR cooling plant TPC To RR 0.3l/min TPC res-rods upgrade RR cooling plant TPC cooling plant TPC Heat exchanger To RR New loop 0.3l/min 3~5l/min

25/3/2009Detector Cooling Project Meeting I7 TOF/PHOS/ITS consolidation activities TOF: improve temperature uniformity –Increase flow, monitor detector pressures (in, out) PHOS: circulation at -30° to check condensation SPD: –Increase efficiency and reduce bubbling effect Installation of new heat exchanger between tank and pump in order to further lower down the C4F10 temperature –Improve monitoring Installation of P,T sensors on each individual line in the proximity of the detector, both for the liquid and the gas phase SSD: –Re-routing lines on the miniframe to reduce siphons

25/3/2009Detector Cooling Project Meeting I8 Re-routing of SSD pipes View of the Miniframe

25/3/2009Detector Cooling Project Meeting I9 Other consolidation activities Switching local → remote: –Last Command (even very old) is sent and executed, loops potential risk –Solution: “double” synchronization (like CMS): copy the commands sent in local control mode into the registers used for remote (PVSS) control. –First script (FW C&V upgrade) made by O.Holme (EN-ICE), will be tested today at 10h30 (TPC) Better description warning/alarm words –The warning/alarm bit-by-bit description will be made available in a new SCY file

25/3/2009Detector Cooling Project Meeting I10 Summary of ALICE cooling systems consolidation activities 2009 WhereWhatHowWhen TPC/TRD Reduce bubbling effectBack-pressure valveWks TPC/TRD Improve vacuum powerAdditional vacuum pumpWks TPC res-rods Improve efficiencyAdditional cooling loop Wks (plant modif.) New pipes laid down wk 12 TPC covers/ bus-bars Improve thermal uniformity New heatersWks Re-route cooling linesIn progress TOF Improve thermal uniformityIncrease flowIn progress SSD Reduce siphonsRe-route linesDone SPD Improve efficiency and reduce bubbling effect New heat exchanger btw pump and tank Done Improve monitoringP,T sensorsApr.09