DCLL ½ port Test Blanket Module thermal-hydraulic analysis

1. DCLL ½ port Test Blanket Module thermal-hydraulic analysis Presented by P. Calderoni March 3, 2004 UCLA

2. Total heat balance 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/m2over 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 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)

3. Pressure losses along in/out pipes from HEX to TBM 40 m/s (52 m/s) Re = 5x105 8 kPa in coax (4.5 kPa w/o SiC) Why keeping the SiC insert? hydraulic diameter: 0.086 m Friction coefficient (Petukhov corr) = 0.013

4. Pipes length L = 80 m x 2 (in / out) Pressure losses = 0.11 Mpa (1.375% of inlet pressure) 10 m 18 m 40 m 18 m

5. Back View Side View turn0.5k Pressure losses in back-plate distribution circuit 90 turn 2k 30% flow split 2k up down Coaxial piping conv / div in transporter 8k x 2 Top, grid plates FW L to R pass FW R to L pass Bottom, grid plates 90 Y conv 8k 90 Y split 8k Pressure losses = 0.04 Mpa (0.0225 MPa w/o SiC) 0.5 % of inlet pressure (0.28 %) 30% flow split 2k 90 turn 2k turn0.5k

6. Pressure losses in first wall cooling channels Grid Plate First Wall Vertical He I/O Manifold Grid Plate He Manifold [ DEMO design ]

7. 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 0.442 kg/s 0.055 kg/s 20 mm 30 mm For q = 0.3 MW/m2 the heat transfer coefficient needs to be at least 4000 W/m2 K to ensure TFWmax < 550 C 38 mm 0.055 kg/s 0.442 kg/s

8. 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. 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 Cost? Efficiency at high heat flux? Reliability? 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 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 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)

9. 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)

10. Summary • Eliminate SiC insert from He coaxial pipe (suggested) • Use ribs to enhance heat transfer (questionable) • 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)