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/m 2 over 90% of FW / 0.5 MW/m 2 over 10% of FW First wall surface = 1.94 m X 0.64 m = 1.25 m 2 Power from radiative flux = 0.4 MW Nuclear heating power = MW Total power handled by the module = 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’ = kg/s (Cp = 5192 J/Kg K)

Pressure losses along in/out pipes from HEX to TBM Why keeping the SiC insert? 40 m/s (52 m/s) Re = 5x10 5 Friction coefficient (Petukhov corr) = kPa in coax (4.5 kPa w/o SiC) hydraulic diameter: m

Pipes length L = 80 m x 2 (in / out) 10 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 turn 0.5k 90 turn 2k 90 Y conv 8k Coaxial piping conv / div in transporter 8k x 2 30% flow split 2k 90 turn 2k turn 0.5k 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 ( 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 kg/s Initial design configuration: m pitch 16 channels per section kg/s total mass flow m x 5 channel length v = 16.1 m/s h = 1375 W/m 2 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/m 2 K to ensure T FW max < 550 C

20mm x 20 mm channels: m pitch 16 channels per section v = 24.2 m/s h = 2000 W/m 2 K dp = 9.4 kPa 10mm x 15 mm channels: m pitch 32 channels per section v = 32.3 m/s h = 2750 W/m 2 K dp = 29 kPa 10mm x 10 mm channels: m pitch 32 channels per section v = 48.4 m/s h = 4000 W/m 2 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 = 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 = MPa (0.6% of total inlet pressure)

ComponentReference pressure dropEnhanced performance In / Out pipes0.11 MPa (1.375%) Flow distribution0.04 Mpa (0.5%) (0.28%) 1 FW and manifolds0.225 Mpa (2.8%)0.144 MPa (1.8%) 2 Top, bottom and grids0.05 Mpa (0.6%) (0.28%) 3 Total0.515 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 v 2 (use higher value to be conservative)