DCLL ½ port Test Blanket Module

thermal-hydraulic analysis

Presented by

P. Calderoni

March 3, 2004 UCLA

Input parameters for the ½ port module (Wong, Sawan March 2005):

Surface heat flux q’’ = 0.3 MW/m2 over 90% of FW / 0.5 MW/m2 over 10% of FW

First wall surface = 1.94 m X 0.64 m = 1.25 m2

Power from radiative flux = 0.4 MW

Nuclear heating power = 0.913 MW

Total power handled by the module = 1.313 MW

Power transferred to He cooling (40% of total) = 0.6 MW

Total heat balance

If inlet / outlet He temperature are fixed at 360 C and 440 C the needed cooling mass flux m’ = 1.265 kg/s (Cp = 5192 J/Kg K)

Pressure losses along in/out pipes from HEX to TBM

Why keeping the SiC insert?

A

mv

40 m/s (52 m/s)

Re = 5x105

hD

LfK

vKp

2

2

Friction coefficient (Petukhov corr) = 0.013

8 kPa in coax

(4.5 kPa w/o SiC)

hydraulic diameter:0.086 m

Pipes length L = 80 m x 2 (in / out)

10 m

18 m

18 m

40 m

Pressure losses = 0.11 Mpa (1.375% of inlet pressure)

Side View Back View

90 Y split

8k

30% flow split

2k

turn0.5k

90 turn

2k

90 Y conv 8k

Coaxial piping conv / div in transporter

8k x 2

30% flow split

2k90 turn

2k

turn0.5k

Pressure losses in back-plate distribution circuit

up down

Top, grid plates

FW L to R pass

FW R to L pass

Bottom, grid plates

Pressure losses = 0.04 Mpa

(0.0225 MPa w/o SiC)

0.5 % of inlet pressure (0.28 %)

First Wall

Grid Plate

Vertical He I/O Manifold

Grid Plate He Manifold

Pressure losses in first wall cooling channels

[ DEMO design ]

0.442 kg/s

0.442 kg/s

0.055 kg/s

0.055 kg/s

Initial design configuration:

0.024 m pitch

16 channels per section

0.884 kg/s total mass flow

1.255 m x 5 channel length

v = 16.1 m/s

h = 1375 W/m2 K

dp = 3.6 kPa

20 mm

30 mm

38 mm

For q = 0.3 MW/m2 the heat transfer coefficient needs to be at least 4000 W/m2 K to ensure TFW

max < 550 C

20mm x 20 mm channels:

0.024 m pitch

16 channels per section

v = 24.2 m/s

h = 2000 W/m2 K

dp = 9.4 kPa

10mm x 15 mm channels:

0.014 m pitch

32 channels per section

v = 32.3 m/s

h = 2750 W/m2 K

dp = 29 kPa

10mm x 10 mm channels:

0.014 m pitch

32 channels per section

v = 48.4 m/s

h = 4000 W/m2 K

dp = 75 kPa

Heat transfer could be enhanced by squared ribs perpendicular to the flow on the high heat flux side, as suggested by S. Sharafat (1 x 1 mm ribs with a 6.3 mm pitch) instead of smaller channel dimension.

With similar heat transfer coefficient the ribbed channels configuration generates 64% of the total pressure losses than the smaller smooth channels.

Preliminary results from 2-D simulation of He flow in the FW channels and manifolds by G. Sviatoslavsky show pressure drops that are a factor of 3 higher than those evaluated with Petukhov’s correlation for the channels only.

Estimated total pressure drop in FW = 0.225 MPa (2.8% of inlet pressure)

Cost?Efficiency at high heat flux?Reliability?

Pressure losses in top, bottom and grid plates (design not finalized)

0.38 kg/s (30% of total flow) is diverted to cool all structures other than the FW.

If a channel geometry similar than the FW is assumed a pressure loss of 10 kPa can be used as a first approximation for each cooling plate

Estimated total pressure losses = 0.050 MPa(0.6% of total inlet pressure)

Component Reference pressure drop

Enhanced performance

In / Out pipes 0.11 MPa (1.375%)

Flow distribution 0.04 Mpa (0.5%) 0.0225 (0.28%) 1

FW and manifolds 0.225 Mpa (2.8%) 0.144 MPa (1.8%) 2

Top, bottom and grids 0.05 Mpa (0.6%) 0.0225 (0.28%) 3

Total 0.515 Mpa (6.4%) 0.3 MPa (3.75%)

Summary

1. Eliminate SiC insert from He coaxial pipe (suggested)

2. Use ribs to enhance heat transfer (questionable)

3. Without a finalized design a lower boundary for pressure losses could be found by scaling the FW losses with v2 (use higher value to be conservative)