1. Pixel Upgrade, CO2 cooling Upgrade Workshop FNAL 8 November 2011 8 November 20111Hans Postema - CERN

2. Why CO2? Radiation hard Not electrically conductive, non corrosive Not flammable, not toxic Has excellent thermodynamic properties for micro- channels. Low dT/dP Low mass Low liquid/vapour density ratio Low viscosity High latent heat High heat transfer coefficient Environmental friendly 28 November 2011Hans Postema - CERN

3. Pressure advantage Intuitively, higher pressures seem a disadvantage but: Gas flow at higher pressures needs smaller pipe diameters Pressure drops due to flow become less significant, allowing smaller pipes Small pipes can easily support the required pressures 38 November 2011Hans Postema - CERN

4. Why is evaporative CO 2 cooling good for HEP detectors? CO 2 allows small tubing Why? Large latent heat & Low viscosity & High pressure Allow high pressure drop Allow low flow Low pressure drop Lower pressure drop Allow very small tubing Liquid Viscosity Temperature (ºC ) (Pa*s) Better CO 2 C3F8C3F8 1e-4 2e-4 3e-4 4e-4 5e-4 -40-20 0 20 Latent Heat of Evaporation (KJ/kg) Better CO 2 C3F8C3F8 Better CO 2 C3F8C3F8 0 100 200 300 -40-20 0 20 Temperature (ºC ) 8 November 2011Hans Postema - CERN4

5. CO 2 allows small tubing Why? Large latent heat & Low viscosity & High pressure Allow high pressure drop Allow low flow Low pressure drop Lower pressure drop Allow very small tubing Latent Heat of Evaporation (KJ/kg) Better CO 2 C3F8C3F8 Better CO 2 C3F8C3F8 0 100 200 300 -40-20 0 20 Temperature (ºC ) Liquid Viscosity Temperature (ºC ) (Pa*s) Better CO 2 C3F8C3F8 1e-4 2e-4 3e-4 4e-4 5e-4 -40-20 0 20 Why is evaporative CO 2 cooling good for HEP detectors? 8 November 20115Hans Postema - CERN

6. CO 2 allows small tubing Why? Large latent heat & Low viscosity & High pressure Allow high pressure drop Allow low flow Low pressure drop Lower pressure drop Allow very small tubing Latent Heat of Evaporation (KJ/kg) Better CO 2 C3F8C3F8 Better CO 2 C3F8C3F8 0 100 200 300 -40-20 0 20 Temperature (ºC ) Liquid Viscosity Temperature (ºC ) (Pa*s) Better CO 2 C3F8C3F8 1e-4 2e-4 3e-4 4e-4 5e-4 -40-20 0 20 Why is evaporative CO 2 cooling good for HEP detectors? But with very high heat transfer capability! 8 November 20116Hans Postema - CERN

7. CO 2 systems in HEP 2 CO 2 cooling systems have been developed for HEP detectors so far. – AMS-TTCS (Tracker Thermal Control System) Q= 150 watt T=+15 o C to -20 o C Operating in space since 20 May 2011 – LHCb-VTCS (Velo Thermal Control System) Q=1500 Watt (2 parallel systems of 750 W) T= +8 o C to -30 o C Operating at -30 o C since 3 years! Both systems are based on the 2PACL principle invented at NIKHEF 8 November 20117Hans Postema - CERN

8. AMS on the ISS 8 November 2011Hans Postema - CERN8

9. VTCS Locations 9 LHCb experimental cavern 55 m transfer tube Evaporator Passive tubing only Cooling Plant All active hardware Transfer tube Concentric assembly 8 November 2011Hans Postema - CERN

10. Baseline concept The LHCb system has a perfect track record, no need to modify the concept 3 years of low temperature operation with no problems at all CMS system has 8 times higher power Bigger pumps and suitable heat exchangers exist on the market 8 November 2011Hans Postema - CERN10

11. Temperatures FPIX and BPIX request different temperatures LHCb concept can not provide 2 temperatures without further research LHCb system includes a backup cooling system The LHCb backup system can run at a different temperature – Virtually the same as 2 cooling plants In CMS, minimal temp. -20 C limited by condensation on the insulation of the supply line 8 November 2011Hans Postema - CERN11

12. Redundant concept For CMS at point 5 we propose 2 identical systems, A and B – only one design needs to be made and debugged FPIX runs on A, BPIX runs on B Different temperatures for FPIX and BPIX without problem If one plant fails or needs maintenance, BPIX and FPIX can both run on either of the two cooling plants but in this exceptional case, they have to agree, on a common temperature. 8 November 2011Hans Postema - CERN12

13. Quality starts with a simple concept. For AMS the 2PACL method was invented – Simple to operate, self stabilizing cooling system. – Minimum amount of actuators and control. 2PACL successfully applied in LHCb-Velo. – Passive in detector cavern – All active components in the distant accessible cooling plant – 1 primary control (P7 accumulator pressure = detector temperature) The 2-Phase Accumulator Controlled Loop (2PACL)

14. Schematic - full 20 July 2011Hans Postema - CERN14

15. Plant P&I 8 November 2011Hans Postema - CERN15

16. LEWA pumps Latest contact with LEWA pumps Enquiry for their lowest temperature options Price estimates for various pump types On photo, special pump for -50 C operation 30 August 2011Hans Postema - CERN16

17. SWEP CO2 Heat exchanger 8 November 2011Hans Postema - CERN17

18. CORA 2kW – control system Control system (1) 8 November 201118Hans Postema - CERN

19. CORA 2kW – control system Alarm diagnostic Alarm list + email & SMS alarm notification Control system (2) 8 November 201119Hans Postema - CERN

20. 1. Setup Setup is made of 8 U-shaped copper tube sections brazed together following procedure studied in previous paragraph 16m long in total, 1.8l, same copper tube as for CMS PIXEL cooling pipes (14mm OD – EN13348) Equipped with a pressure sensor (+DAQ), a manual pump (static hydraulic pressure) and a volumetric scale. 20 Certification procedure Pipe mock-up study Jérôme DAGUIN - PH/DT/PO

21. 21 Elastic limit: 124bar Certification procedure Pipe mock-up study Plastic deformation of the pipe Elastic deformation of the pipe Jérôme DAGUIN - PH/DT/PO Results

22. Results: Rupture pressure 22 Pipe rupture: 247bar Certification procedure Pipe mock-up study Jérôme DAGUIN - PH/DT/PO

23. Copper tube test Very large diameter results in very low flow speed Measure 2-phase flow behavior in horizontal, vertical and inclined tubes Measure the heat exchange between supply and return lines Measure heat pick-up through the insulation 30 August 2011Hans Postema - CERN23

24. Long transfer lines studies - Status 07/07/2016Jérôme DAGUIN - PH/DT/PO24 Piping installed – 2 lines of 65m – 14mmOD tubes: 14,7l of CO 2. Safety pressure test done (90bar) and OK. DAQ commissioning: – All sensors (14 PTs and 28 TTs) installed and cabled. – Software ready (labview based interface). – Noisy acquisition card needs to be replaced. » Measurement can already start with software patch or noisy cards. Cooling plant chiller will be ready in the next weeks. Insulation to be installed when first test and commissioning done.

25. Long transfer lines studies – Tests planning Step #1: Circulation tests at room temperature line1. – Debugging and playing with the flow (0 to 15g/s). Install the first layer of insulation. Step #2: Circulation tests at low temperature line1. – Playing with the flow (0 to 15g/s), the temperature (-20)C to +20°C) and the power (0 to 650W). Step #3: Circulation tests with the two lines at low temperature. – Playing with the flow (0 to 15g/s), the temperature (-20)C to +20°C) and the power (0 to 650W). Install the second layer of insulation. Step #4: Circulation tests at low temperature line1. – Playing with the flow (0 to 15g/s), the temperature (-20)C to +20°C) and the power (0 to 650W). Step #5: Circulation tests with the two lines at low temperature. – Playing with the flow (0 to 15g/s), the temperature (-20)C to +20°C) and the power (0 to 650W). 07/07/2016Jérôme DAGUIN - PH/DT/PO25

26. João Noite PH-CMX-DS BPix Tube With Bends Boundary Conditions Range: Temperature, T setpoint = -10°C and -20°C Mass Flow, m = 0.35 to 1.72g/s Mass Flux, G = 255 to 1114kg/m 2.s Heat Load, Q = 48.93 to 226.07W Heat Flux, q = 1.97 to 9.1kW/m 2 Fixed Outlet Vapor Quality, x out ≈ 0.50 Theorectical Models: Single-Phase Flow Pressure Drop: Darcy-Weisbach with Colebrook Friction Factor Heat Transfer Coefficient: Dittus-Boelter Two-Phase Flow Pressure Drop & Heat Transfer Coefficient: CO 2 Evaporation Inside Tubes; Lixin Cheng, Gherhardt Ribatski, Jesús Moreno Quibén, John R. Thome, 2006 Model Boundary Conditions Range Tube Diameter: 0.6 to 10mm CO 2 Saturation Temperature: -28 to +25°C Mass Flux: 50 to 1500kg/m 2.s Heat Flux: 1.8 to 46kW/m 2 BPix Tube Mock-up Mock-up Tube Data: Material: SS 304L Length = 5650 mm Inner Diameter = 1.41 mm Wall Thickness = 50μm Surface Roughness ≈ 15μm Nr. of Bends = 18x 90° Bend Radius ≈ 3 mm Electrical Resistance ≈ 4.15Ω Sensorx [m] Tin0 S10.32 S21.14 S31.945 S42.845 S53.66 S64.565 S75.385 S85.95 m, T in P in P out V.A -+-+ S8S1S2 S3 S4 S5 S6S7

27. João Noite PH-CMX-DS Test Conditions: Q = 177.94W q = 7.16kW/m 2 m = 1.23g/s G = 800kg/m 2.s Pin = 22.42Bar Tin= -17.89°C Xout = 0.53 Test Results: ΔP = 3.35Bar ΔT = 7.0°C Theory Results: ΔP = 2.60Bar ΔT = 5.78°C A B D M I SLG S SW Two Phase Tests TEST 14

28. Test conclusions (1) CO 2 is an outstanding cooling fluid for small and long channels. 1.4mm ID & 5.65m Length Tube @ -20°C & 150W → ΔP = 2.6Bar & ΔT = 6.3°C. Numbers will be improved as the detector tube is foreseen to be 1.5mm ID. The influence of tube bends in this r/d ratio does not affect significantly the overall ΔP. Tests show that the ΔP difference between experimental and theory is small indicating that the CO 2 bulk temperature is well predicted. Higher heat loads require more mass flow which will increase ΔP and ΔT 8 November 2011Hans Postema - CERN28

29. Test conclusions (2) As shown in tests, ΔP increase will flood the first section of the evaporator with sub- cooled liquid. Sub-cooled liquid influences detector temperature gradient and has much lower HTC when compared with 2-Phase. Tests at low mass flow show high influence of environmental heat due to poor insulation of test section. Evaporator tube should pass trough DC-DC converters and Port Cards before entering the Detector. Detector flow regime should be Annular for optimum HTC. Burn tests indicate that Dryout boundary region is well predicted in the flow pattern map, however its HTC seems to be overestimated at heat fluxes lower than 9kW/m². 8 November 2011Hans Postema - CERN29

30. New FPIX loop layout 8 November 2011Hans Postema - CERN30 Courtesy: Kirk Arndt

31. BPIX loop layout 8 November 2011Hans Postema - CERN31

32. Converging concepts All loops start with a capillary to minimize flow difference between on-off operating conditions DC-DC converter and opto converters at the beginning of the loop to start boiling and enter the annular flow regime Detector tube optimized for acceptable temperature gradient Return line of larger diameter to avoid unnecessary temperature gradient 8 November 2011Hans Postema - CERN32

33. Next Step - BPix Full Loop P in V.A - S6 S1 S2 S3S4 S5 T out m T in P in + V.A - DC-DC Converter & PC Tube Length = 2400 mm Inner Diameter = 1.8 mm Wall Thickness = 100μm Electrical Resistance ≈ Ω + Detector Tube Material: SS 304L Length = 5650 mm Inner Diameter = 1.41 mm Wall Thickness = 50μm Electrical Resistance ≈4.15Ω Detector Supply & Return Tube Length = 2400 mm Inner Diameter = 1.8 mm Wall Thickness = 100μm T in S1 T in S6 T out S2 S3 S4 S5 T out P out João Noite PH-CMX-DS Sensorx [m] SUPPLYTin,Pin0 DC-DC & Port Cards Tin0.41 S10.435 S20.885 S31.365 S41.845 S52.325 S62.77 Tout2.8 DETECTOR Tin5.74 S15.765 S26.55 S37.695 S48.84 S59.985 S611.35 Tout11.375 RETURNTout,Pout14.755 33

34. BPix Full Loop DC-DC Converter Tube Supply / Return TubeDetector Tube João Noite PH-CMX-DS Sensorx [m] Tin0 S10.025 S20.475 S30.955 S41.435 S51.915 S62.36 Tout2.39 Sensorx [m] Tin0 S10.025 S20.81 S31.955 S43.10 S54.245 S65.61 Tout5.635 34

35. CO 2 cooling support To support the CO 2 cooling projects in particle physics several test systems are under development: Cora (CO 2 Research Apparatus) – Fixed test plant for CERN based research (0-2kW, +20 to -35ºC) Marco (Multipurpose Apparatus for Research on CO 2 – Fully automatic (User friendly) CO 2 test system for general use (0-1kW, +20 to -45ºC) – Base design for future on detector cooling plants (Atlas IBL, Belle-2) Traci (Transportable Refrigeration Apparatus for CO 2 Investigation) – Small test system for laboratory use – New simplified 2PACL concept to reduce cost and complexity (0-200W, +20 to -40ºC) 35 Traci Cora Marco

36. Fermilab CO 2 plant 20 June 2011VERTEX 2011 - Hans Postema - CERN36

37. Cooling System Temperature Control Cooling System uses three on/off condensing units and a trim heater to control temperature Simon Kwan, Erik Voirin37 CMS CO2 Cooling Test Stand Test Results

38. Cooling System Capacity Test Run Test Heater at 5000W for several hours – System remained stable at the temperature set point. – Temperature stayed within 0.05 o C of set point – Only needed to run a single condensing unit -20 o C temperature set point Condensing unit #3 ran solo during the capacity test System has cooling capacity to spare (or backup units) Simon Kwan, Erik Voirin38 CMS CO2 Cooling Test Stand Test Results

39. Cooling System Disruption Tests Temperature set point change test – Showed maximum temperature overshoot of 0.4 o C (even on cool down from room temperature) Load change test – Simulates the turning on/off of some of the detectors electronics Simon Kwan, Erik Voirin39 CMS CO2 Cooling Test Stand Test Results

40. Cooling System Disruption Tests Run test heater at a specific load, immediately apply increase (or decrease) load. – System remained stable within 0.2 o C of set point. – One temperature overshoot then back to set point in ~10 minutes – Overshoot appears somewhat proportional to load change: 0.1 o C error per 1000W load change Largest changes tested is 4000W  2000W  4000W Simon Kwan, Erik Voirin40 CMS CO2 Cooling Test Stand Test Results

41. Cooling Success Not only a matter of selecting the right fluid A concept that uses the maximum amount of industrial experience and industrial technology assures maximum reliability Design the system keeping the very limited access in mind. Only components of outstanding quality should be used, fluids can be expensive, refurbishments too 20 June 2011VERTEX 2011 - Hans Postema - CERN41

42. Tentative schedule Freeze concept – Dec 2011 Design ready – April 2012 Start purchasing components – Jan 2012 Construction completed – Dec 2012 Commissioning completed – Jul 2013 Ready for installation in UXC – Aug 2013 – This schedule is definitely very aggressive 20 July 2011Hans Postema - CERN42

43. CMS Pixel CO2 Collaborators CERN CMS/DT/Nikhef – Jerome Daguin, Joao Noite, Hans Postema, Paola Tropea, Bart Verlaat, Lucasz Zwalinski FNAL – Simon Kwan, Richard Schmitt, Erik Voirin Lyon – Nick Lumb, Jean Christophe Ianigro Perdue University – Kirk Arndt PSI/ETHZ – Willi Bertl, Robert Becker 8 November 2011Hans Postema - CERN43

44. Conclusions The concept for the full cooling system is now becoming established The concept for the plant is mostly defined Engineering, design and component selection have started Layout for FPIX and BPIX are converging towards the optimum Measurements of the full in-detector loop for the BPIX will start soon Control part requires major effort, support from the DT group is crucial It is important to do more measurement to determine the heat transfer between chip and cooling tube 20 June 2011VERTEX 2011 - Hans Postema - CERN44