CO2 Cooling Research @ IPNL Nick Lumb, 28/01/09

Programme 2009 Jan – April: Build blow system based on NIKHEF / CERN design Cooling power ~144 W (PIX layer 1 circuit) May – Sept: Build re-circulating system based on VELO design Cooling power ~1 kW

Blow system – CERN design

Blow system – components (1) Liquid CO2 bottle √ Air Liquide, 50 l Mass flow meter √ Rheonik RHM 015 Swagelok metering valve √ To adjust the flow rate Swagelok proportional relief valve √ To adjust the back pressure (CO2 temp.) Heat exchanger Home built concentric tube, 2.8 m heat exchange length

Blow system – components (2) Julabo F32-EH chiller / heater √ To heat CO2 to 30°C before venting -35 to 150°C 150W cooling power @ -20°C, 2kW heating power Re-use in re-circulating system (accumulator) Test capillary √ To be provided by Hans 1.5 mm o.d., 76 micron wall thickness Contacts for low voltage current source (heating) Pressure gauges √ Commercial fridge (isolate test capillary from environment) √ Temperature sensors + read-out √ Miscellaneous Swagelok connectors √ Pipe insulation √

Re-circulating system Condenser Pump Heat exchanger Restrictor 2-Phase Accumulator Heat in Heat out 1 2 3 4 5 6 P7 P4-5 Long distance The 2-Phase Accumulator Controlled Loop (2PACL) B. Verlaat (NIKHEF)

Main extra items needed beyond blow system Gear pump E.g. Gather type 1mx-x/12-11 Minimum pulsing Being tested by B. Verlaat Condenser Could re-use Louvain 2kW chiller Re-use blow system heat exchanger? Or buy one (SWEP B12H/1P-SC-U) Two-phase accumulator Re-use Julabo heater / cooler Need to buy / make pressure vessel Bart rule of thumb: pressure vessel 1.5 x volume of rest of system

Re-use of concentric tube exchanger Will blow system exchanger be big enough? Heat transfer calcs for 2-phase flow not elementary! Excel sheet For blow system, pipes 12x10 and 6x4, flow rate 1cc/s: can get away with length ~2m For Louvain chiller: Flow max. = 35 l/min. C6F14 Require 1 kW cooling power at CO2 temp. -10°C Assume chiller operates at -23°C → Heat exchange length needed ~2.8m Pressure drop (~2 bar) may be a problem

Conclusion Starting to build blow system Hope to have it ready with full temperature read-out by end April Will then build re-circulating system Tool for testing heat transfer options for PIX and eventually Si strip tracker