1. Final Presentation CO2 as potential medium for detector-cooling at CERN
Members of project:
Christian Brosch
Andreas Maier
Tamara Bubeck
Persons in support:
Prof. Dr. Ing. Walter Czarnetzki
Dr. Ing. Friedrich Haug

2. Table of contents Overview of test ridge and installed components
(including the cycling process)
Improvements
Results for the measurement (α – coefficient)
Maximum error estimation
Summary
Prospects

3. Overview Test ridge (schematic)5 6 4 3 2 1
New „brick“

4. Assembly of ridge

5. Cyclic process: Compression 1 24 3 2
State 1 2
Temperature Ti [°C]
-36,7
105
Pressure pi [bar]
11,2 35
Enthalpy hi [kJ/kg]
435
556
Entropy si [kJ/kg]
2,03
2,23
Compression

6. One-way-valve Compressor Oil separator
Cyclic process: Compression 1 2
One-way-valve
Compressor
Oil separator

7. Cyclic process: Compression 1 2
Data Compressor
max. power absorption 3,2 kW
weight: 49 kg
max. high pressure: 43 bar
cooling rating: 6058 W
Oil separator returns ca. 98% of the exhaust oil back to compressor
One-way-valve avoid back flow of oil or CO2
Pressure control valve opens at 40 bar to avoid damages

8. Cyclic process: Condensation: 2 31 4 3 2
State 2 3
Temperature Ti [°C]
105
Pressure pi [bar] 35
34,6
Enthalpy hi [kJ/kg]
556
200,3
Entropy si [kJ/kg]
2,23
1,03
Condensation

9. Condensor (secondary circuit)
Cyclic process: Condensation: 2 3
Condensor (secondary circuit)
Cooling medium: R404a
Refrigeration capacity: 4,0-8,7 kW(adjustable)
Cooling compressor: Bock HGX22P
Heat exchanger: plate heat exchanger
water cooled

10. Cyclic process: Expansion 3 41 4 3 2
State 3 4
Temperature Ti [°C]
-36,7
Pressure pi [bar]
34,6
11,2
Enthalpy hi [kJ/kg]
200,3
Entropy si [kJ/kg]
1,00
1,03
Expansion

11. Cyclic process: Expansion 3 4
Expansion valve
Coriolis mass flow meter
Pre-heating

12. Cyclic process: Expansion 3 4
Coriolis mass flow meter Expansion valve to expand CO2 gas Pre-heating (0,75 kW) to adjust the starting point of measurement in two phase area and vapor quality factor
Mass Flow
Accuracy in %
100 kg/h
260 kg/h

13. Cyclic process: Evaporation 4 13 2
State 4 1
Temperature Ti [°C]
-36,7
Pressure pi [bar]
11,2
Enthalpy hi [kJ/kg]
200,3
435
Entropy si [kJ/kg]
1,03
2,03
Evaporation

14. Cyclic process: Evaporation 4 1
Testsection
After-heating

15. Cyclic process: Evaporation 4 1
Components of Testsection:
length 5,5 meter
Copper tube
inner diameter 14mm
outer diameter 16mm
5 heating elements each 1000 Watt
4 heating elements each 250 Watt
Thermal conductive paste SI-setral-HSC/N
PT100 surface sensors for measuring outside tube temperature
Aluminum sheet
Isolation stone wool, λ = 0,038W/(mK) at 50°C; ( Steel ≈ 50W/(mK) )
After-heating to make sure that CO2 is completely evaporated before entering the compressor

16. Location of sensors for surface temperature
OT4
OT3
OT2
OT1

17. Measurement „bricks“ Material: AlCuMgPb
Pressure sensor: SHD-U_25 transmitter 0-25 bar(Testsection)
or SHD-U_40 transmitter 0-40 bar Accuracy: ± 0,5%
Temperature sensor: PT100A 15/ Accuracy:±0,1K

18. Improvements

19. More effective Isolation
get off the aluminum tape
Fix aluminum sheet to avoid heat
losses

20. Heat loss because of convection
Application over all heating coils
Heat convection to the copper pipe is more effective and faster

21. Heat loss because of convection
Q=α·A·(TW-TF)
discrepancies caused by convection as well as small parts radiation
 A total loss of 13 W

22. New aluminum brick after pre-heating
Application of pressure transmitters and fluid temperature sensors in „Aluminium bricks“ to define conditions in entrance of test-section

23. Current measurement The heating coils were connected in three-phase
Every phase gets his own current measurement , so current will be added in total
Modification of cables in the switching cabinet

24. New oil separator Two possible solutions: better oil separator
99% separation efficiency
activated carbon filter
 99 +% separation efficiency
cost ca. 250€
cost ca. 2000€

25. DAQ

26. Data acquisition

27. Results of measurement

29. 1,3 kW
2,3 kW

30. Results for the α - coefficient
q = 19,9 kW/m2
m = 85 kg/h

31. Maximal error estimation
The maximum error of heat transfer coefficient can be calculated by: Accuracy of measurement intruments:
Instruments
Measurand
Accuracy
AT20 B10 ∆U
±1,5 %
PT100A 15/10 ∆T
± 0,1K
 for max. heat capacity : 5,5 kW ∆α =18 %

32. Oscillation of the system

34. Summary improvement of isolation Modification of data acquisition
Oscillation of the „whole system“
 insufficient cooling medium: R404a
Long delivery times

35. Prospects Decision for more efficient oil separator
Extensive performance tests
Development of flow visualization
Measurements of flow stability according CMS constraints
 Next project group starts in april

36. Thank you for your attention
Any questions left?