1. 1 Nikhef Activities on CO 2 Cooling Bart Verlaat, Nikhef Introduction meeting with FOM director W. van Saarloos 1 Picture: LHCb-VELO evaporator

2. CO 2 cooling @ Nikhef (1) Evaporative CO 2 cooling is very promising for detectors: –Need small tubing (5-10x lower mass than conventional cooling systems) –Excellent heat transfer properties (5-10x higher than conventional systems) –Due to high system pressure more design freedom (pressure losses not significant) –CO 2 is very safe and clean to work with. Since 10 years Nikhef is developing CO 2 cooling systems. Other experiments (HEP and others) are investigating this Nikhef technology for their thermal control.

3. CO 2 cooling @ Nikhef (2) Nikhef has developed a new cooling principle called 2PACL. (2-Phase Accumulator Controlled Loop) The 2PACL concept is a mix of technologies from different “kitchens” (Space, refrigeration, central heating and fire fighting) CO 2 fire extinguisher Refrigeration system Central heating system Satellite thermal control

4. CO 2 systems in HEP 2 CO 2 cooling systems have been developed for HEP detectors so far. –AMS-TTCS (Tracker Thermal Control System) {Build by NLR} Q= 150 watt T=+15ºC to -20ºC –LHCb-VTCS (Velo Thermal Control System) {build in house} Q=1500 Watt T= +8ºC to -30ºC Both systems are based on the 2PACL principle invented at Nikhef. Default technology for Atlas and CMS upgrade Promising for future satellite cooling (NLR) 4 AMS

5. HX 100ºC What we actually do: Replace the burner heat by the detector heat. Place all the hardware in the “heated room” away from the detector Place the radiator in a refrigerator Replace water by CO 2 to boil at sub-zero temperatures Introduce a heat exchanger between the supply and return line, to make the CO 2 boiling. Replace the expansion vessel by a more sophisticated accumulator from satellite cooling systems. Varying the pressure in the accumulator and let the CO 2 boil at any temperature you want. From central heating to 2PACL cooling Central heating system 2PACL Cooling system Result: 2PACL is an easy to control cooling principle which is accurate, low mass and passive in the detector

6. 6 Evaporator section Component box on satellites exterior Heat exchanger Pump Evaporator tube TTCS Space radiator The AMS-Tracker Thermal Control System (AMS-TTCS) AMS Accumulator

7. 7 Evaporator The VTCS cooling plant CO 2 rack Velo Module with cooling block The LHCb-Velo Thermal Control System (LHCb-VTCS)

8. The cooling tube temperature is: –Easy to control –Very stable –Independent of primary cooler temperature 8 Accumulator temperature = Cooling tube temperature Accumulator temperature = Cooling tube temperature Temperature of space radiator LHCb-VTCS Temperature of the chiller Temperature (ºC) 1 orbit (~1.5h) Time AMS-TTCS 0 -10 -20 -30

9. CO 2 developments for future HEP experiments bverlaat@nikhef.nl 9 The Dutch C 1 O 2 flu is becoming pandemic; The whole world is getting infected…………. Compressor plant in CERN-Cryolab Blow-system in IPN-Lyon Blow-system in Karlsruhe 2PACL system in RWTH-Aachen Blow system in CERN-DT CMS Blow system in SLAC 2PACL system in Nikhef Atlas

10. CO 2 2PACL Lab Cooler Demand for: Mass flow Enthalpy Pressure Demand for: Power Supplies: Power Supplies: Massflow Enthalpy Pressure Supplies: Temperature Pressure Voltage Supplies data: HTC Pressure drop CHF Dry out PC with PVSS to control the cooler and experiment 2PACL with PLC Test box with experiment Power supply Supplies: Cold Demand for: Temperature Cryostat 10

11. Conclusions 11 CO 2 cooling works very well in AMS and LHCb. It has a promising future to become a HEP detector default. Auke-Pieter’s Mantra adopted in CMS