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

2. 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

3. Blow system – CERN design

4. 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

5. Blow system – components (2)
Julabo F32-EH chiller / heater √
To heat CO2 to 30°C before venting
-35 to 150°C
150W cooling -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 √

6. 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)

7. 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

8. 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

9. 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