1. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH Design of the thermosiphon Test Facilities Thermosiphon Cooling Review A. MORAUX PH Dpt / DT Group CERN SEPTEMBER 1 st 2009

2. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 2 Summary  Interests and proposal overview  Thermodynamic cycle  Operating conditions  Design parameters  System integration  Control requirements  Critical Issues  Conclusion Evaporator Condenser

3. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 3 Interests for a gravity-driven cooling concept  Provide a natural circulation of the fluid  Avoid working components in the main circuit  Access refrigeration units in the surface and make maintenance easier  Substitute a compressor stage by the pit height using hydrostatic pressure difference  Suction pressure of the compressors is not a limit anymore

4. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 4 Process Diagram 13.5 Bar +20.0 C 13.5 Bar -25.0 C 0.59 Bar -48.0 C 0.8 Bar +20.0 C 80 m PIT SURFACE CAVERN

5. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 5 Cycle of the cooling system Operation at -40°C (evaporation temperature in the boiling channel)

6. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 6 Operating Conditions  Purging and filling the system  Start-up  Nominal operating conditions with 0.1 kW loop  Nominal operating conditions with full power

7. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 7 Design parameters: Test sections and Mass flow (1/4) Evaporation temperature [°C] Nominal power load [kW] Outlet quality Inlet quality Latent heat [kJ/kg] Mass flow rate [g/s] -402.00.90.58106.358.8 -252.00.90.48100.847.2 02.00.90.2490.333.5 -250.10.90.48100.82.3 -350.10.90.55104.52.7 mass flow rate baseline under different operating conditions Nominal operation

8. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 8 Design parameters: Vessel and Piping (2/4)  Frictional Pressure drops ♦Pipe length = 200 m ♦DN25 Downward pipe Δp = 0.005 bar ♦DN50 Upward pipe Δp = 0.041 bar  Hydrostatic Δp over 80m ♦Downward pipe Δp = 12.9 bar ♦Upward pipe Δp = 0.049 bar  Storage vessel ♦Usefull volume 600 L ♦Approximative internal diameter and length: 0.8 m, 1 m ♦Heat pickup in the tank: 250 W @ -48°C

9. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 9 Design parameters: Chiller (3/4) Evaporation temperature [°C] +15+100-10-20-25-30-40 Condensation temperature [°C] 13.48.2-2.3-13-24.1-29.7-34.7-48.6 Required power for 0.1 kW loop operation: around 2 kW @ -48 °C

10. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 10 Design parameters: Chiller (4/4) Evaporation temperature [°C] +15+100-10-20-25-30-40 Condensation temperature [°C] 13.48.2-2.3-13-24.1-29.7-34.7-48.6 Required power for 2x 1 kW loop operation: around 12 kW @ -48 °C

11. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 11 System integration  Surface (SUX1) ♦Vessel: 2 m 2 ♦Chiller: 4 m 2 ♦Working space: 6 m 2  Pit (PX15)  Cavern (USA15) SUX 1 PIT

12. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 12 System integration  Surface (SUX15)  Pit (PX15) ♦Two pipes between surface and cavern ♦Bypass at the bottom of the pit ♦Bypass height: 2 to 4m  Cavern (USA15)

13. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 13 System integration  Surface (SUX15)  Pit (PX15)  Cavern (USA15): Installation scheme to be defined ♦Test sections: around 6 m 2 ♦Distribution racks, filter: 2 m 2 ♦Control cabinet: 1 m 2

14. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 14 Control Requirements  Control system based on CERN UNICOS framework  Around 115 Input/output splitted between surface and cavern  Supervision & Operation layer facilities  Data archiving system  Non redundancies required for the test facilities

15. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 15 Service requirements  Surface ♦Water distribution ♦Electrical power (chiller + control system) ♦Compressed Air ♦Ethernoet Network  Cavern ♦Electrical power (heaters + control system + test sections evaporator) ♦Compressed air ♦Ethernet Network

16. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 16 Critical issues  Low pressure in part of the system (return gas pipe + vessel)  Very low leak rate requirements  Avoid evaporation in the liquid line  Avoid elbows on the pipes This means ♦Important risks analysis to perform before purchasing ♦Rigorous quality insurance ♦Well prepared on-site tests campaign

17. EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH 17 Conslusion and Next steps Gravity-driven cooling systems are appealing but the feasibility needs to be demonstrated first and studied with precision First actions  Build the 1:8 scale test facility for autumn to perform test with C3F8  Focus on risks assessment and quality assurance (welding, …)  Sharp component selection Long term:  Perform process simulation at the first test facility scale  Provide a model reflecting real dynamics to simulate the process off-line and test design parameters and control strategies