1. M. Battistin – 28 th May 2010EN/CV/DC1 M. Battistin (EN/CV/DC) 28 th May 2010 Detector Cooling Project III Thermosiphon Workshop - Back-up solutions to the ATLAS ID Thermosiphon: centrifugal compressors

2. M. Battistin – 28 th May 2010EN/CV/DC2 Centrifugal oil free compressors A market survey has been launched last summer to identify alternative compressors to Haug ones: Labyrinth Membrane Oil free screw Three main lines of investigation are now active: Turbocor oil free magnetic bearing centrifugal compressor McQuay oil free magnetic bearing centrifugal compressor Another oil free gas bearing centrifugal compressor The three possibilities are and will be investigated. All of them give some concerns.

3. M. Battistin – 28 th May 2010EN/CV/DC The most promising alternative to HAUG compressors is centrifugal compressors: full oil free solution high power density (one single machine could make the work the ID cooling needs) High rotation speed (48 krpm) leads to an almost vibration less system The cost of one of this compressor is about half of the Haug one. Positive feed-backs form the market after about 10 years of industrial applications on fridge systems (mainly HVAC industry). “it is extremely reliable!!” Hermetic compressor system guarantee high leak- tightness of the process. Mandatory feature to manage the activated fluid we will have in some year. 3 Turbocor project

4. M. Battistin – 28 th May 2010EN/CV/DC4 The Turbocor solution on paper M. Battistin - EN/CV/DC15th April 2010 First calculations show that the smallest Turbocor compressor TT-300 (the one we have now) could manage 90% of the flowrate required by ATLAS ID cooling. Larger compressors are available from Turbocor (TT-400 and TT-550) and McQuay (from 1000 kW). Discharge pressure will be most probably limited to 7-8 bar a. The surface condensation will allow to gain the other 8-9 bar needed to feed the detector.

5. M. Battistin – 28 th May 2010EN/CV/DC5 Turbocor qualification process We shall qualify this compressor with our gas (R218 = C 3 F 8 ) We have bought a test bench (see picture). The system has been modified to test the compressor performances (new piping, pressure regulator and flow meter). A test area has been set-up in SMI2 (close to 298). -Test procedure -No support from Turbocor -A list of problems: Turbocor compressor has been designed to handle R134a, the standard fluid for refrigeration industry. This technology is less then 10 years old and is progressively conquering the market now. Main parameters to consider for fluid change; Compressor cooling: apparently R134a @ ≈+4°C, R218 @ ≈ - 40°C? Corrosion problems? Material compatibility problems? Control issues: shall we (you) modify the internal code? Shaft forces check; Critical components in case of fluid change; Detailed Test Procedure; The test of the compressors foresees many phases with different fluids (R134a, C3F8, blends) and will take many months to reach the full qualification. The support of the design team would be extremely important… or even fundamental: what is the guarantee of a try and error process?? Danfoss-Turbocor never answered…

6. M. Battistin – 28 th May 2010EN/CV/DC Test bench bought… 6 Evaporator Condenser Turbocor Primary water ≈20 °C 380 kW TTPTPT FTFT PTPT Cooling line Chilled water ≈6 °C 300 kW Power 80 kW

7. M. Battistin – 28 th May 2010EN/CV/DC …and modified to test the compressor 7 Evaporator Condenser Turbocor Primary water ≈12 °C 80 kW TTPTPT FTFT PTPT Cooling line Power 80 kW

8. M. Battistin – 28 th May 2010EN/CV/DC8 …McQuay answered McQuay Europe is qualifying this machines for the European power (50 Hz – 400 V) now. We were searching for support from the design team: Meeting with McQuay Europe in Rome on 22 nd of April 2010. T. Watson (Chief Engineer of McQuay USA) and L. Paolella (General Manager of McQuay Europe). T. Watson is verifying on paper the feasibility of this project. The “stone-wall” condition could critical and could limit the maximal performances of the machine. The control of the machine should be most probably modified: L. Sorabella (control specialist of McQuay could help on this point). McQuay compressors use the same technology of Turbocor. The design offices worked together to develop Turbocor in ‘90. McQuay launched more recently a series of larger compressors (more than 1 MW) using this technology. P m’ Stall Stone wall Meeting with Padova University on 26 th of May (two days ago). Prof Zilio and Prof. Cavallini. We are defining a three partners collaboration and identifying one resource dedicated to the compressor qualification project working in strict collaboration with CERN, McQuay (Italy and USA) and UniPadova. Phone conference to be organized soon.

9. M. Battistin – 28 th May 2010EN/CV/DC9 Gas bearing oil free compressor “It will be possible to design for above mentioned parameters as a one machine 1.2 kg/s which will be based on following components: High speed asynchronous motor 33 kW / 65 000 rpm (rotor: diameter 66.6 mm, active length 105 mm, materials: heat treated carbon steel, Cu, Ti), stator: outer diameter 160 mm, air cooled. Fully dynamic self acting radial & axial gas bearings (materials: Al alloy, heat treated carbon steel, graphite composite) One stage working stage containing blades impeller D=68 mm / 65 000 rpm (material: Al alloy, outer body of the spiral case carbon steel) Pressure body - galvanized carbon steel or Al alloy Frequency converter (FC)” “It will be possible to design for above mentioned parameters as a one machine 1.2 kg/s which will be based on following components: High speed asynchronous motor 33 kW / 65 000 rpm (rotor: diameter 66.6 mm, active length 105 mm, materials: heat treated carbon steel, Cu, Ti), stator: outer diameter 160 mm, air cooled. Fully dynamic self acting radial & axial gas bearings (materials: Al alloy, heat treated carbon steel, graphite composite) One stage working stage containing blades impeller D=68 mm / 65 000 rpm (material: Al alloy, outer body of the spiral case carbon steel) Pressure body - galvanized carbon steel or Al alloy Frequency converter (FC)” We are organizing a technical visit to the supplier in the next 2 weeks. Question marks: Is that a brand new design? Is the company solid enough (Haug II)? We will start debugging it in few years? …

10. M. Battistin – 28 th May 2010EN/CV/DC10 Compressors project conclusions Only centrifugal compressors give oil free guarantee and size We have a Turbocor machine but we don’t have Turbocor support We could have McQuay support but we don’t have McQuay machine Many experts already warned us on the most critical points of the qualification process. We need to identify one resource, already expert in turbomachines that could work 100% on this project in collaboration with CERN and the other partners.