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Status of MHD/Heat Transfer Analysis for DCLL
US-ITER TBM MeetingUS-ITER TBM Meeting
February 14-15, 2007
Rice Room, Boelter Hall 6764, UCLA
Thermofluid / MHD group
Presented by Sergey Smolentsev
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
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”
Conclusions from the previous analysis, 2
• High exit temperature (700C) is achievable • FCI provides reasonable MHD pressure drop reduction.• The design window appears to be very narrow.
Reference parameters: SiC=100 S/m and kSiC=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
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
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
-0.15 -0.1 -0.05 0 0.05 0.1 0.15R adia l d istance, m
400
800
1200
1600
Tem
pera
ture
, C
lam inar flow m odelturbulent flow m odel
DEMO
E
g
DB
=500
=100
=5
A C
Scaling analysis for poloidal ducts for ITER and DEMO
ITER D-T DEMO
Re=30,500 61,000
Ha=6350 Ha=11,640
Ha/Re=0.208 Ha/Re=0.190
N=1320 N=2217
Gr=7.22x109 Gr=3.52x1012
r=11.1 r=70.3
Gr/Re=2.36x105 Gr/Re=5.76x107
Ha/Gr=8.80x10-7 Ha/Gr=3.31x10-9
a/b=0.55 a/b=1.0
L/a=50 L/a=18
•The lack of neutrons and reduced PbLi exit temperature in ITER (470C) 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
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, 1st and 2d return
ducts
225
210
210
Cross-sectional area of theDCLL blanket with dimensions
SHF = 0.58 MW/m2
NWL = 3.08 MW/m2
PbLi T in/out = 500/700CHe T in/out = 350/450C
What is new ?
New analysis for DEMO, 2
A. Effect of the FCI thickness on the MHD pressure drop: tFCI=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; tSiC=5 mm
C. Heat transfer for the “reference ” case (tsic=5 mm, SiC=100 S/m, kSiC=2W/m-K, Ufront=5.8 cm/s, Urtrn=3.1 cm/s) for the front and two return ducts
D. Heat transfer for the “reduced SiC” case (tsic=5 mm, SiC=20 S/m, kSiC=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?
New analysis for DEMO, 3
FCI: 2.5 mm FCI: 5.0 mm FCI: 10.0 mm FCI: 15.0 mm
Front duct. SiC=100 S/m.
Effect of the FCI thickness on the velocity profile
New analysis for DEMO, 4
SiC=500 S/m SiC=200 S/m SiC=50 S/m SiC=5 S/m
Front duct. tFCI=5 mm.
Effect of SiC on the velocity profile
New analysis for DEMO, 5
FCIthickness
mm
Maximum velocity in the
parallel gap
Maximum velocity in the Hartmann gap
Maximum jet velocity
Velocity at the duct center
2.5 4.2 0.07 6.7 0.07
5 3.0 0.04 5.0 0.08
10 2.1 0.03 3.5 0.21
15 1.7 0.01 2.8 0.35
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
Maximumvelocity in the
parallel gap
Maximum velocity in the Hartmann gap
Maximum jet velocity
Velocity at the duct center
500 8.0 0.15 8.7 0.15
200 4.4 0.08 6.4 0.08
100 3.0 0.04 5.0 0.08
50 1.8 0.03 3.5 0.20
20 1.0 0.01 2.3 0.45
5 0.5 0.01 1.4 0.8
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 tSiC on the velocity profile
New analysis for DEMO, 6
Rwall
Rgap
RFCIRFCI
~
“True” parameter, which describes the FCI effectiveness as electric insulator, is its “electrical resistance,” i.e. tFCI/SiC
R is the MHD pressure drop reduction factor Circuit analogy
Electric current path
Effect of SiC and tSiC on the MHD pressure drop
New analysis for DEMO, 7
0 1 2 3 4Polo ida l d istance , m
500
550
600
650
700
750
Pb
Li b
ulk
tem
pe
ratu
re, C
Reference caseFront duct1st re turn duct2d return duct
2-D MHD and 3-D Heat Transfer computations for the DEMO blanket,including PbLi front and two return ducts. Reference case. Laminar flow.
Computedvelocity profile
Cross-sectional temperaturedistribution at 1 m from the bottom
Bulk temperature alongthe flow path
Reference case. MHD & Heat Transfer
New analysis for DEMO, 8Reference case. Temperature distribution in the poloidal ducts
X=0.2 m X=0.8 m X=1.4 m X=1.8 m
Fro
nt
1st r
etu
rn2d
ret
urn
-0.15 -0.1 -0.05 0 0.05 0.1 0.15R adia l d istance, m
400
800
1200
1600
Te
mp
era
ture
, C
Tem perature dropacross the FC I
-0.15 -0.1 -0.05 0 0.05 0.1 0.15R adia l d istance, m
400
500
600
700
800
900
Te
mp
era
ture
, C
Tem perature dropacross the FC I
-0.15 -0.1 -0.05 0 0.05 0.1 0.15R adia l d istance, m
400
500
600
700
800
Te
mp
era
ture
, C
Tem perature dropacross the FC I
New analysis for DEMO, 9
Reference case. Summary of Heat Transfer data
Duct Max FCI
ΔT, front
Max FCI
ΔT, side
Max PbLi-Fe T, front
Max PbLi-Fe T, side
front 140 K 500 K 480C 600C
1st R 200 K 200 K 490C 520C
2d R 200 K 200 K 490C 520C
New analysis for DEMO, 10
Reduced SiC (20 S/m) case. Front duct. FCI ΔT. Interface T. FCI 3 FCI 1, 2 Interface 3 Interface 1, 2
200 K 220 K 495C 560 C
New analysis for DEMO, 11
Turbulent case. Front duct. FCI ΔT. Interface T.
FCI 3 FCI 1, 2 Interface 3 Interface 1, 2
240 K 220 K 495C 560 C
New analysis for DEMO, 12
Case Max FCI
ΔT, front
Max FCI
ΔT, side
Max PbLi-Fe T, front
Max PbLi-Fe T, side
Ref. 140 K 500 K 480C 600C
Red.
200 K 220 K 495C 560C
Turb. 240 K 220 K 495C 560C
Comparison for the three cases. Front duct
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
New analysis for DEMO, 14
Suggested modifications in the FCI design (S. Malang)
FCI 1FCI 2
PbLi
A. Double layer FCI B. Goffered FCI
Reduces ΔT in the FCI
More stress tolerance
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)
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)
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