1. M. Battistin – 1 st September 2009 EN/CV/DC 1 M. Battistin (EN/CV/DC) 1 st October 2009 ATLAS cooling Group - Thermosiphon solution for ATLAS ID cooling consolidation

2. M. Battistin – 1 st September 2009 EN/CV/DC 2 HAUG compressors show technical limits PR thermal screen others 4 liquid lines 4 gas lines 6 Haug compressors condenser liquid tank pneumatic valve manual valve manual valve dummy load mixed water Sub-cooler BPR pixel 6 X SCT manual valve pneumatic valve ATLAS requested to evaluate a possible alternative to the present compressor station. The main reasons are: Reliability: many failures registered in the present compressors Cleanliness: wear of components obliges to an important filtering process Leaks: developing with time due (in part) to vibrations UX15 USA15

3. M. Battistin – 1 st September 2009 EN/CV/DC 3 Alternative compressors? ATLAS cooling group (J. Godlewski, D. Giugni, M. Battistin) has launched an extended research of alternative solution on the present HAUG Compressors: Oil Free Screw Compressors. Labyrinth Piston Compressors Membrane Compressors Centrifugal Compressors

4. M. Battistin – 1 st September 2009 EN/CV/DC 4 The thermosiphon solution PR thermal screen others 4 liquid lines 4 gas lines condenser liquid tank pneumatic valve manual valve manual valve dummy load Heater BPR pixel 6 X SCT manual valve pneumatic valve A gravity driven circulation (thermosiphon) could be a solution. The thermo-siphon solution could provide: Reliability: no active component in the system Cleanliness: no wear of components Leaks: reduction of connection points and no vibrations Low temperature Chiller UX15 USA15 Surface This solution has the advantage to manage a wide spectrum of blends (C3F8- C2F6 for instance) without mechanical modification on the circuit or new verification of the compressors efficiency.

5. M. Battistin – 1 st September 2009 EN/CV/DC 5 A low efficiency cycle A B C D E F E1E1 G The low efficiency of the system is compensated by the extremely simplicity of the installation: no active equipments are installed in the process in contact with the detector.

6. M. Battistin – 1 st September 2009 EN/CV/DC 6 P&I of the installation -55 °C = 400 mbar -67 °C = 200 mbar -40 °C = 850 mbar -30 °C = 1300 mbar -25 °C = 1670 mbar Return DP = 90 mbar 2 kW 6 kW

7. M. Battistin – 1 st September 2009 EN/CV/DC 7 The fridge cascade Primary Water 25°C Cooling source is the primary water coming form the cooling towers: ≈25 °C Two fridge systems in cascade takes the temperature to -70 °C. The first stage uses R404a and the second stage R23. The second stage cools down a small liquid brine circuit R134a used to condensate the C3F8 in the condenser of the thermo siphon circuit. The condensed C 3 F 8 falls in the liquid receiver due to gravity. First Chiller (R404a) Second Chiller (R23) -30°C-70°C -67°C Condenser Liquid receiver Brine (R134a)

8. M. Battistin – 1 st September 2009 EN/CV/DC 8 Power requirements Primary Water 25°C A 280 kW chiller evaporating @ -70°C requires about 300 kW compressor motor power and 100 m3/h of primary water consumption form the cooling tower. The present evaporative cooling systems evaporates 60 kW @ -20°C requires 5 compressors running (110 kW) and 24 m3/h of water form the mixed water circuit (TRANE chiller). The mixed and chilled water production for ATLAS requires 4 TRANE chillers (2 for mixed water and 2 for chilled water). The overall cooling power is 4.800 kW @ 0°C. They have 1.600 kW compressors motor and requires about 1000 m3/h of primary cooling water form the cooling towers. TRANE Chiller 0°C Mixed or chilled Water 6 or 12°C

9. M. Battistin – 1 st September 2009 EN/CV/DC 9 Many possible suppliers The fridge cascade shall be: 1)Fully redundant (2 x 100% or 3 x 60% solutions can be adopted) 2)Highly reliable (proven performances and MTBF) 3)Automatic (the control system will be independent to the thermo siphon one) We will search for fully industrial hand-key solutions realized by reliable company with a proven list of similar installation realized in the past. We are now in the Market Survey (MS) phase. The visit to the companies premises will be part of the selection criteria of the MS. The Invitation to Tender (IT) will be sent to the selected companies only. The long list is: Axima Refrigeration (D), Axima (CH), Angelantoni (I), Froid Seicar (F), Mayekawa Europe (B), Clauger (F), others are going to be selected

10. M. Battistin – 1 st September 2009 EN/CV/DC 10 Visit to Angelantoni on June 29 th 2009 Clear previous experience on refrigeration for industry: 1)Brine chilling units, package design, air-cooled or water-cooled, refrigerating capacities from 30 to 800 kW, temperature range from 0°C to – 80°C. 2)Refrigerating systems for harmful gas or vapors condensation, to avoid environment pollution, custom-designed according to Customer requirements, capacity range from 30 to 2.000 kW, temperature range from 0°C to – 80°C. The budget estimation for a cooling unit 280 kW @ -70°C is around 1.500 k€ The ID cooling consolidation needs about 200 kW @ -60°C. 14.0 m 8.0 m 5.0 m ≈1.500 k€

11. M. Battistin – 1 st September 2009 EN/CV/DC 11 Space could be a problem

12. M. Battistin – 1 st September 2009 EN/CV/DC 12 There is a minimal power required to run the system The liquid temperature increases form the surface to the cavern due to the environmental thermal load. The final (cavern) temperature increases with the mass flow. There is a minimal mass flow required to avoid the temperature increases more than the saturation one. There is a minimal cooling power we need to condensate the minimal flow rate required. A minimum requirement is around 2 kW@ -60 C

13. M. Battistin – 1 st September 2009 EN/CV/DC 13 Conclusions Gravity driven circulation evaporative cooling systems seems a promising technology to replace the compressors in the evaporative cooling systems. It is foreseen to install a test bench in PX15; the design parameters of this test bench installation fit with ATLAS IBL cooling needs. We are working to build a very small scale test bench to validate the first design assumptions in bdg 191. Perfluorocarbon blends solutions could be adopted to the thermo- siphon to improve the performances. Azeotropicity could be a problem. We are ready to start the purchase phase of this project.