1 / 22

Update on wound-truss carbon fiber structures: Optimization, tests and simulations

Update on wound-truss carbon fiber structures: Optimization, tests and simulations. Claudio BORTOLIN (CERN) Enrico DA RIVA (CERN) Corrado GARGIULO (CERN) Manuel GOMEZ MARZOA (CERN) WG4 Meeting - 16 th October 2012. Contents. D08 prototype: test data post-processing

stormy
Download Presentation

Update on wound-truss carbon fiber structures: Optimization, tests and simulations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Update on wound-truss carbon fiber structures: Optimization, tests and simulations Claudio BORTOLIN (CERN) Enrico DA RIVA (CERN) Corrado GARGIULO (CERN) Manuel GOMEZ MARZOA (CERN) WG4 Meeting - 16thOctober 2012 WG4 Meeting - 16th October 2012

  2. Contents • D08 prototype: test data post-processing • Prototype optimization • Design parameters • Stave calculations • Cooling fluid calculations • D08 prototype: simulation • D09 prototype: preliminary tests with water • General conclusion WG4 Meeting - 16th October 2012

  3. Data post-processing • D08 water tests -> Stave thermal resistance calculation • From Silicon to water, two thermal resistances can be defined: • Water tests allow recalculation of HTC: RtConv RtCond-Stave Water Silicon Pipe inner wall Laminar & Gnielinski WG4 Meeting - 16th October 2012

  4. Two-phase C4F10 tests: overview • Inlet vapor quality: • Superheating at stave outlet: T = const x = const • Mass flow rate calculation: 1 p [bar] where L is latent heat [kJ kg-1]: 3 3’ 2 4 Qstave[W] • Usually: h [kJ kg-1] WG4 Meeting - 16th October 2012

  5. D08: water vs. C4F10 @0.3 W cm-2 Evaporative cooling system performs as good as single-phase water WG4 Meeting - 16th October 2012

  6. D08: water vs. C4F10 @0.5 W cm-2 • Results independent of the mass flow rates. • Controlling the vapor quality at the inlet/outlet is very important. • Almost subcooled liquid at the stave inlet! WG4 Meeting - 16th October 2012

  7. D08: C4F10 tests discussion • Two extreme cases: • Low vapor quality at the stave entrance: subcooled liquid entering stave? • ꜛ m, ꜛ HTC, but ꜛΔp. Since pOut = constant, ꜛpInlet, ꜛTsat-Inlet, ꜛΔTFluid • Low vapor quality at the stave entrance: saturated liquid entering stave? • Mass flow rate too low: superheated vapor at stave outlet WG4 Meeting - 16th October 2012

  8. Data post-processing • D08 C4F10 tests: HTC prediction and flow characterization • Pool boiling or convective boiling? HTC predicted through Rt 0.3 W cm-2 0.5 W cm-2 *Assumedsmooth pipe. Forcorrelations, powerisassumedto be distributeduniformlyaroundthecooling pipe. Used Cooper (1984) and Liu-Winterton (1991) correlationsfor HTC. WG4 Meeting - 16th October 2012

  9. Design parameters • Preliminary calculations: • Heat transfer path: • Si-glue • Glue-wrapping CF • Wrapping CF-CF sleeve • Heat distribution within CF sleeve • CF sleeve-cooling pipe • Cooling pipe-fluid 5 4 6 2 3 1 • Materials: • Carbon Fiber: • Wrap fiber: K13D-2U CF: kFiber ~ 450 W m-1 K-1 ; kTransv ~ 1.2 W m-1 K-1 • Carbon Paper: kFiber ~ 550 W m-1 K-1 ; kTransv ~ 1.2 W m-1 K-1 • Glue: k ~ 1 W m-1 K-1 • Pipe (Polyimide): k= 0.12 W m-1 K-1 , OD = 1.5 mm, wall 35 µm thick • Silicon: k = 150 W m-1 K-1 WG4 Meeting - 16th October 2012

  10. Stave calculations • 0. D08 prototype • Decrease stave width to 15.5 mm • Increase CF width to 1.75 mm • Increase CF width to 1.90 mm • Increase CF thickness to 100 µm • Decrease number of fibers to 40 • Increase wrap angle to 40 deg • Increase wrap angle to 60 deg • Increase glue thickness to 200 µm and decrease its th. cond. to 0.5 W m-1K-1 • Increase pipe outer diameter to 2.5 mm • New prototype (D09) Strategy: estimate the ΔT that every part of the structure will introduce. WG4 Meeting - 16th October 2012

  11. Stave calculations: conclusion • 0. D08 prototype • Decrease stave width to 15.5 mm • Increase CF width to 1.75 mm • Increase CF width to 1.90 mm • Increase CF thickness to 100 µm • Decrease number of fibers to 40 • Increase wrap angle to 40 deg • Increase wrap angle to 60 deg • Increase glue thickness to 200 µm and decrease its th. cond. to 0.5 W m-1K-1 • Increase pipe outer diameter to 2.5 mm • New prototype (D09) WG4 Meeting - 16th October 2012

  12. Cooling fluid calculations • Convection pipe wall-fluid: • Several HTCs considered • Stave height = 5 mm, fiber wrap angle = 23 deg • Heat transfer area inner pipe wall only below 180-η angle at sleeve. HTC variation Increase pipe section Decrease pipe section WG4 Meeting - 16th October 2012

  13. Stave optimization • Stave: • Improvements without increasing mat. budget: • Reduce stave thickness to 15 mm • Increase wrap angle (eventually, use HC Plate) • Improvements increasing mat. budget: • Increase CF width • Increase carbon fiber thickness • Cooling fluid: • Increasing pipe diameter reduces ΔTPipe-Ref , but increases mat. budget (espec. single phase) • Little improvement when increasing HTC pipe-fluid • Further considerations: • Single-phase or Two-Phase? • Fluid? • For better understanding heat transfer mechanisms, CFD simulation was updated • D08 prototype modeled and simulated. WG4 Meeting - 16th October 2012

  14. D08 prototype simulation: model • UPDATED CFD Model: • Symmetric (only a sector of stave modeled) • Imposed HTC fluid-wall at the pipe inner wall. HTC = 1700 W m-2 K-1 • Results shown for Twater = 15 °C and q’ = 0.3 W cm-2 • Natural convection with ambient air is included HTC = 10 W m-2 K-1 (also included top part) • Thermal conductivity CF: anisotropic: solver did not cope with such different values • Th. Cond used: different, but analytical calculations show no influence in transversally to CF Geometry views of the model. • Carbon Fiber: • Wrap fiber: K13D-2U CF: kFiber ~ 450 W m-1 K-1 ; kTransv ~ 40W m-1 K-1 • Carbon Paper: kFiber ~ 550 W m-1 K-1 ; kTransv ~ 40W m-1 K-1 WG4 Meeting - 16th October 2012

  15. D08 prototype simulation: results Temperature of the silicon: WG4 Meeting - 16th October 2012

  16. D09 prototype: design parameters • Comments: • 54 fibers (thermal “bridges”): p ~ 3 mm • Gluing defects found near the connections (inlet/outlet stave end). • All the results for these tests are preliminary. D09 prototype geometrical parameters. WG4 Meeting - 16th October 2012

  17. D09 prototype: gluing defects • Gluing defects found near the connections (inlet/outlet stave end) • Heater is there detached from the silicon • Hotspot appeared after the 10 L h-1 , 0.3 W cm-2 test. Inlet/Outlet First hotspot because gluing defect. 10 L h-1, 0.3 W cm-2 case. Second hotspot appears (heater detaches from silicon). 5 L h-1, 0.3 W cm-2 case. Hotspot location 5 L h-1, 0.3 W cm-2 case. WG4 Meeting - 16th October 2012

  18. D08 vs D09 water test@0.3 W cm-2 WG4 Meeting - 16th October 2012

  19. D08 vs D09 water test@0.5 W cm-2 • Conclusion: • The gluing defects make difficult to analyze how the D09 performs vs D08. • Preliminary results suggest the behavior is quite similar in both, with D08 performing slightly better. WG4 Meeting - 16th October 2012

  20. Water tests: results WG4 Meeting - 16th October 2012

  21. General conclusion • Post-processing data allows to understand the thermal resistance of the prototype. • Through analytical calculations + simulations, an optimal design can be reached. • It is very important to quantify the influence of the manufacturing process (CF wrapping, gluing…) on the final result. • Guarantee nice gluing: increasing glue thickness a low impact thermally. • Gluing in vacuum: prevent from having voids in the glue layer. • The solution with a high conductivity plate is attractive if the material budget from the D08-like structures keeps increasing. • Tests with squeezed pipes will require a low pressure/leak-less system WG4 Meeting - 16th October 2012

  22. Update on wound-truss carbon fiber structures: Optimization, tests and simulations Claudio BORTOLIN (CERN) Enrico DA RIVA (CERN) Corrado GARGIULO (CERN) Manuel GOMEZ MARZOA (CERN) WG4 Meeting - 16thOctober 2012 WG4 Meeting - 16th October 2012

More Related