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How to reduce cooling duties in CLIC

How to reduce cooling duties in CLIC. M. Nonis EN/CV CLIC Workshop 2014 - 4 th February 2014 . Outline. Original design Principles Constraints Open issues Possible optimizations on cooling Variation on temperature at exit of cooling towers Location of cooling towers

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How to reduce cooling duties in CLIC

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  1. How to reduce cooling duties in CLIC M. Nonis EN/CV CLIC Workshop 2014 - 4th February 2014

  2. Outline • Original design • Principles • Constraints • Open issues • Possible optimizations on cooling • Variation on temperature at exit of coolingtowers • Location of coolingtowers • Variation of temperature range • Water treatment • Conclusions Aknowledgements: G Peon CLIC Workshop 2014 - M. Nonis

  3. Preamble (or disclaimer?) This presentationisrather qualitative than quantitative and does not have the objective of covering all possible options. Figures shown are eithercalculated, or deductedusingsomescalingparameter. Examples are on coolingsystemsfor the main tunnel. The objective is to launch the discussion on some possible changes and seewhetherthey are acceptable for CLIC or not. Then, specific cases mightbestudied in more detail. CLIC Workshop 2014 - M. Nonis

  4. Original design: general principles • CLIC facilities have been divided into 5 major cooling sectors according to: • Functional and operational requirements • Thermal loads • Dimensions, geographical distribution: • Facilities (Drive beam injector building) • HVAC and cooling plants (keep reasonable size) • Environmental impact (no cooling towers on surface Points) • Further (sub)separation possible during detailed design. Ref: M Nonis - CLIC Cost & Schedule WG – 24.2.2011 CLIC Workshop 2014 - M. Nonis

  5. Design principles: constraints • Distribution loads between air and water: 10% -90% • Minimize space occupancy in main tunnel. • Main cooling circuit in tunnel embedded in concrete. • No cooling towers on surface Points, all cooling towers centralized in Prevessin. CLIC Workshop 2014 - M. Nonis

  6. Cooling: sectors 1, 2 & 5 Sector 2 Sector 5 (both sides) Sector 1 CLIC Workshop 2014 - M. Nonis

  7. Cooling: sectors 3 & 4 Sector 4 (UTRs, dumps, loops) Sector 3 CLIC Workshop 2014 - M. Nonis

  8. Cooling open issues • Available space in tunnel for main pipes/ducts and equipment: • Booster pumps location; • Bypass valves, manifolds (available space, balancing of circuit); • Connection to drains. • Available space in shafts. • Optimising location of primary stations wrt shafts availability. Ref: M Nonis - CLIC Cost & Schedule WG – 24.2.2011 CLIC Workshop 2014 - M. Nonis

  9. Cross section cooling major issues • Missing items: • fire fighting, • compressed air, • chilled water Manifold DN500 Bypass, connection to drain Ref: M Nonis - CLIC Cost & Schedule WG – 24.2.2011 CLIC Workshop 2014 - M. Nonis

  10. Main coolingparameters * Average water consumption at CERN: 750 m3/h CLIC Workshop 2014 - M. Nonis

  11. Possible optimisations in cooling • Whatcanbedonedifferently to improveoperationcostor pending issues? • At whichcost or drawback? • What do we gain? CLIC Workshop 2014 - M. Nonis

  12. 1. Variation T out fromcoolingtowers • Followwet bulb temperature variation through the day/months to reduce water temperature at exit of coolingtowers, thereforereduce the flow rate needed on primary circuit. • Extend the primary circuit to UTRC • Regulatetemperature of secondary circuit via a 3-way valve. • Optimum working point does not coincidewith the lowest possible approach • Regulation on temperature more difficult 38 - 45 °C 10 - 25 °C 47 °C Circuit 3 - Q1=4’600 - 6’342 m3/h 27 °C

  13. 1. Variation T out fromcoolingtowers • Missing items: • fire fighting, • compressed air, • chilled water • Cons: • Creationof cooling station in the UTRCs • Complexityin operation • Additionalpipes (primary circuit) in the main tunnel • Prons • Lowerelectrical power requested (15%) • Bypass and manifold, connection to drain simplified • Primary circuit combinedwithfirefighting network (tbc) Add circuit 3 – ND350 – in tunnel Manifold DN250 Primary circuit CLIC Workshop 2014 - M. Nonis

  14. 2. Modify location of coolingtowers Group circuits in differentway….each station closer to user Gain in electricalconsumption (few %) Loseoperationalflexibilitybetweenindependentsystems (e.g. maintenance). CLIC Workshop 2014 - M. Nonis

  15. 3. Coolingtowers on surface Points • Eachsectoriscooled by a dedicatedcoolingtowerlocated in the surface point. • Concerned surface points will serve 2 sectors to maximizeredundancies. • Make up from local network. (50 m3/h) CLIC Workshop 2014 - M. Nonis

  16. 3. Coolingtowers on surface Points CLIC Workshop 2014 - M. Nonis

  17. 3. Coolingtowers on surface Points • Cons: • Strongerenvironmentalimpact (outside CERN) • Bigger surface needed for installation • Impact on shaft dimensions? • Prons • Smallerpipe diametersin tunnel • Lowerelectrical power requested (25%) • No need for booster pumps • Bypass and manifold, connection to drain simplified • Balancing of circuit simpler and more reliable • Missing items: • compressed air, • Fire fighting • Chilled water Add circuit 3 – ND350 – in tunnel Manifold DN250 Fire fighting? CLIC Workshop 2014 - M. Nonis

  18. 4. Temperature range increase • Increase of temperaturedifferencebetweeninlet and outlet; on primarysidekeep constant the range in the coolingtowers of 20 K: • Recoverenergy to beusedinternally at CERN if it matches runschedule. • For a 5 K increase: • T out = 52 °C acceptable for the equipment? • Decrease of flow rates ~20% in concerned circuits. • No change of size to be able to copewhenheatrecovery not running • Decrease of electrical power for primarypumps >20% 45 °C 45 °C 50 °C 52 °C 25 °C Circuit 3 - Q1=6’342 m3/h Q2=5’073 m3/h 27 °C CLIC Workshop 2014 - M. Nonis

  19. 4. Temperaturerange increase • Cons: • Higherinstallation cost • Pending issues not solved • Prons • Lowerelectrical power requested (20%) • Lowermake up water consumption (20%) • Wasteheatrecoverywill help acceptance of the project. • Missing items: • fire fighting, • compressed air, • chilled water Manifold DN500 Bypass, connection to drain CLIC Workshop 2014 - M. Nonis

  20. 5. Water treatment • Water treatment proportional to make up: • Treatment against scaling, fouling, corrosion • Biocide and biofilm treatment Raw water (300 μS/cm) make up to compensate evaporation and discharge 30 μS/cm Dischargewater(850 μS/cm)to prevent accumulation of dissolved salts System to recycle water beforereject Discharge water from the circuit Disconnection tank Demineralised water to the circuit Concentrate to the waste water Ultra filtration Filter at the size of the bacteria Reverse osmosis Softener

  21. 5. Water treatment • This is a totally new proposalunderstudy • tests and assessment of the results to bedone. • (Possible) Cons: • Investmentcost to beevaluatedwithexpectedlifetime of the system • Impact on operationof the recylcing system to ensure full performance. • Prons • Decrease of water consumption, >50% • Decrease of use of chemicals and biocide • Decrease of rejected water volumes…….(waste water drain) • Compliance with new laws on water reject in France and Switzerland The companyensuresthatitiseconomicallyinteresting (severalhundredskCHFoverall) in operationcost: tbcwith respect to CERN costs.

  22. Summing up

  23. Ventilation DB Injector building • 11 MW - modular solution, every 50-100 mtrsaccording to precisionrequested. • Optimize ventilation if temperatureshigherthan 25 °C accepted: passive cooling (e.g.: no cooling of air installed no chilled water). Onlyheating in winterinstalled. • Acceptable for a working place if for a limitednumber of workinghourstemperature >26 °C . Would 100 hrsbe acceptable? • Basic requirement: • Good solarprotection(colors, glazing) • Good thermal isolation of the building. • Ventilation during night • Additional option: building partially underground shallincrease the thermal inertia of the building wouldlimit the maximum temperature at ~28 °C also in Summer. • Othersystems to increase thermal inertia (puits canadiens, dephaseurs) CLIC Workshop 2014 - M. Nonis

  24. Conclusions • All data presented are to be considered as first estimate, several details/information missing. • Most critical technical point at present to solve: available space in tunnels. • Some of the solutions can be combined together • Use of cooling towers in surface points is highly recommended. CLIC Workshop 2014 - M. Nonis

  25. THANK YOU FOR YOUR ATTENTION CLIC Workshop 2014 - M. Nonis

  26. Main cooling parameters 1/2 CLIC Workshop 2014 - M. Nonis

  27. Main cooling parameters2/2 CLIC Workshop 2014 - M. Nonis

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