1. Status of MHD/Heat Transfer Analysis for DCLL US-ITER TBM Meeting February 14-15, 2007 Rice Room, Boelter Hall 6764, UCLA Thermofluid / MHD group Presented by Sergey Smolentsev

2. Layout Conclusions from the previous MHD/Heat Transfer analysis for DCLL MHD phenomena and scaling analysis for poloidal ducts New analysis for the DCLL DEMO blanket Status of DCLL-related R&D

3. Conclusions from the previous analysis, 1 Many results for DCLL had been obtained prior to the External Review Meeting at ORNL (Aug. 15-16, 2006) The analysis covered MHD/Heat Transfer issues for DCLL DEMO and ITER TBM 20-page TBM Tech. Note SS2, Rev. 1, S. Smolentsev, “Heat Transfer Analysis for DEMO, ITER H-H and D-T”

4. Conclusions from the previous analysis, 2 High exit temperature (700  C) is achievable FCI provides reasonable MHD pressure drop reduction. The design window appears to be very narrow. Reference parameters:  SiC =100 S/m and k SiC =2 W/m-K Serious concerns still remain on the PbLi-Fe interface temperature and FCI ΔT Heat transfer is very sensitive to changes in the PbLi flows. Complex MHD phenomena, including 2-D MHD turbulence, buoyancy-driven flows etc., should be taken into account DEMO

5. Conclusions from the previous analysis, 3 Both ITER scenarios in normal (and even abnormal) conditions look to be acceptable, i.e. all restrictions on the FCI ΔT and the PbLi-Fe interface T can be easily met Flow/heat transfer phenomena in DEMO and ITER are expected to differ significantly, both qualitatively and quantitatively ITER H-H and D-T

6. Summary of MHD/Heat Transfer phenomena in DCLL A.Formation of high- velocity near-wall jets B. 2-D MHD turbulence in flows with M-type velocity profile C. Reduction of turbulence via Joule dissipation D. Buyoncy driven flows E. Strong effects of MHD flows and FCI properties on heat transfer DEMO E g D B  =500  =100  =5 AC

7. Scaling analysis for poloidal ducts for ITER and DEMO ITER D-TDEMO Re=30,50061,000 Ha=6350Ha=11,640 Ha/Re=0.208Ha/Re=0.190 N=1320N=2217 Gr=7.22x10 9 Gr=3.52x10 12 r=11.1r=70.3 Gr/Re=2.36x10 5 Gr/Re=5.76x10 7 Ha/Gr=8.80x10 -7 Ha/Gr=3.31x10 -9 a/b=0.55a/b=1.0 L/a=50L/a=18 The lack of neutrons and reduced PbLi exit temperature in ITER (470  C) are the main reasons why ITER flow physics differs from that in DEMO The most pronounced differences are expected in regard to buoyancy-driven flows, which are significantly more intensive under DEMO conditions Smartly designed sub-module experiment in ITER may result in data, which can be extrapolated to DEMO conditions (see N. Morley) ITER versus DEMO

8. New analysis for DEMO, 1 New dimensions New SHF and NWL New PbLi and He inlet/outlet T More detailed distributions for He flows 5, 2.5, 10 and 15 mm FCI Front, 1 st and 2d return ducts 225 210 Cross-sectional area of the DCLL blanket with dimensions SHF = 0.58 MW/m 2 NWL = 3.08 MW/m 2 PbLi T in/out = 500/700  C He T in/out = 350/450  C What is new ?

9. New analysis for DEMO, 2 A.Effect of the FCI thickness on the MHD pressure drop: t FCI =2.5, 5, 10 and 15 mm;  SiC =100 S/m B.Effect of  SiC on the MHD pressure drop:  SiC =5-500 S/m; t SiC =5 mm C.Heat transfer for the “ reference ” case (t sic =5 mm,  SiC =100 S/m, k SiC =2W/m-K, U front =5.8 cm/s, U rtrn =3.1 cm/s) for the front and two return ducts D.Heat transfer for the “ reduced  SiC ” case (t sic =5 mm,  SiC =20 S/m, k SiC =2W/m-K) for the front duct E.Heat transfer for the “ turbulent ” case (reference case parameters but the flow is turbulent) for the front duct S.Smolentsev, “Upgrades of MHD/Heat Transfer Analysis for DCLL DEMO, TBM Tech. Note TBM-SS3, 21 p., Feb.05, 2007 What has been done?

10. New analysis for DEMO, 3 FCI: 2.5 mmFCI: 5.0 mmFCI: 10.0 mmFCI: 15.0 mm Front duct.  SiC =100 S/m. Effect of the FCI thickness on the velocity profile

11. New analysis for DEMO, 4  SiC =500 S/m  SiC =200 S/m  SiC =50 S/m  SiC =5 S/m Front duct. t FCI =5 mm. Effect of  SiC on the velocity profile

12. New analysis for DEMO, 5 FCI thickness mm Maximum velocity in the parallel gap Maximum velocity in the Hartmann gap Maximum jet velocity Velocity at the duct center 2.54.20.076.70.07 53.00.045.00.08 102.10.033.50.21 151.70.012.80.35 Effect of the FCI thickness on the jet velocity, velocity at the duct center and in the gap. Front duct.  SiC =100 S/m.  SiC S/m Maximum velocity in the parallel gap Maximum velocity in the Hartmann gap Maximum jet velocity Velocity at the duct center 5008.00.158.70.15 2004.40.086.40.08 1003.00.045.00.08 501.80.033.50.20 201.00.012.30.45 50.50.011.40.8 Effect of the FCI electrical conductivity on the jet velocity, velocity at the duct center and in the gap. Front duct. 5 mm FCI. *All velocities in the tables are scaled by the mean velocity, i.e. 5.8 cm/s Effect of  SiC and t SiC on the velocity profile

13. New analysis for DEMO, 6 R wall R gap R FCI ~ “True” parameter, which describes the FCI effectiveness as electric insulator, is its “electrical resistance,” i.e. t FCI /  SiC R is the MHD pressure drop reduction factorCircuit analogy Electric current path Effect of  SiC and t SiC on the MHD pressure drop

14. New analysis for DEMO, 7 2-D MHD and 3-D Heat Transfer computations for the DEMO blanket, including PbLi front and two return ducts. Reference case. Laminar flow. Computed velocity profile Cross-sectional temperature distribution at 1 m from the bottom Bulk temperature along the flow path Reference case. MHD & Heat Transfer

15. New analysis for DEMO, 8 Reference case. Temperature distribution in the poloidal ducts X=0.2 mX=0.8 mX=1.4 mX=1.8 m Front 1 st return 2d return

16. New analysis for DEMO, 9 Reference case. Summary of Heat Transfer data DuctMax FCI ΔT, front Max FCI ΔT, side Max PbLi-Fe T, front Max PbLi-Fe T, side front140 K500 K 480  C600  C 1 st R200 K 490  C520  C 2d R200 K 490  C520  C

17. New analysis for DEMO, 10 Reduced  SiC (20 S/m) case. Front duct. FCI ΔT. Interface T. FCI 3FCI 1, 2Interface 3Interface 1, 2 200 K220 K 495  C560  C

18. New analysis for DEMO, 11 Turbulent case. Front duct. FCI ΔT. Interface T. FCI 3FCI 1, 2Interface 3Interface 1, 2 240 K220 K 495  C560  C

19. New analysis for DEMO, 12 CaseMax FCI ΔT, front Max FCI ΔT, side Max PbLi- Fe T, front Max PbLi- Fe T, side Ref.140 K500 K 480  C600  C Red.  200 K220 K 495  C560  C Turb.240 K220 K 495  C560  C Comparison for the three cases. Front duct

20. New analysis for DEMO, 13 Temperature drop across the FCI and the maximum PbLi-Fe interface temperature is a concern Thermal stress analysis should be performed for different flow conditions and FCI thicknesses If the stress is too high, changes in the FCI design will be needed Realistic maximum allowable interface temperature should be determined based on the corrosion/deposition considerations CONCLUSIONS

21. New analysis for DEMO, 14 Suggested modifications in the FCI design (S. Malang) FCI 1 FCI 2 PbLi A. Double layer FCIB. Goffered FCI Reduces ΔT in the FCI More stress tolerance

22. Status of DCLL-related R&D, 1 Two turbulence models for LM flows in a blanket have recently been developed. S. Smolentsev & R. Moreau, Modeling quasi-two-dimensional turbulence in MHD ducts flows, Proc. 2006 Summer Program, CTR, Stanford University, 419-430 (2006) Scaling analysis for the PbLi flows in poloidal ducts (ITER and DEMO) has been performed (presented by N. Morley)

23. Status of DCLL-related R&D, 2 Differential reduced-scale MHD sub- module has been proposed for testing in ITER (presented by N. Morley and C. Wong) Manifold experiment and complimentary modeling are in progress (presented by K. Messadek and M. Ni)

24. Status of DCLL-related R&D, 3 A problem for testing the pressure equalization effect has been formulated, and first 3-D runs started with HIMAG Discussions on the initialization of the FCI/Heat Transfer experiment are in progress (K. Messadek & S. Smolentsev) New round of studies for buoyancy driven flows in DCLL (2-D and 3-D) has been started