The fusion program in the Karlsruhe Institute of Technology (KIT) leads the R&D of the DEMO helium-cooled pebble bed (HCPB) breeding blanket within the work package breeding blanket (WPBB) of the Eurofusion Consortium in the European Union (EU). A new design of the HCPB breeder zone, with a layout inspired by a nuclear reactor fuel rod arrangement, was developed recently and called the fuel-breeder pin concept. In addition, a mock-up (MU) of this fuel-breeder pin was designed and manufactured at KIT in order to test and validate its thermal–hydraulic performance. This paper reports on the results of the first experimental campaign dedicated to the fuel-breeder pin MU testing that was performed in the Helium Loop Karlsruhe (HELOKA) facility. The paper presents: (i) the integration of the fuel-breeder pin MU into the HELOKA loop including considerations of the experimental set-up, (ii) an overview of the plan for the experimental campaigns, and (iii) a discussion of the experimental results with a focus on aspects relevant for the validation of the thermal–hydraulic design of the HCPB breeder zone

Abou-Sena, Ali

Ghidersa, Bradut Eugen

Hernandez, Francisco A.

Lux, Martin

Rey, Joerg

Schlindwein, Georg

Zhou, Guangming

English

Ghidersa, Bradut-Eugen

Hernández, Francisco A.

KITopen

Experimental Thermal–Hydraulic Testing of a Mock-Up of the Fuel-Breeder Pin Concept for the EU-DEMO HCPB Breeding Blanket

KIT – University of the State of Baden-Wuerttemberg andNational Research Center of the Helmholtz AssociationIntroductionExperimental Thermal-hydraulic Testing of a Prototypical Mock-up of the Fuel-breeder Pin Concept for the EU-DEMO HCPB Breeding BlanketSummaryAli Abou-Sena, Bradut-Eugen Ghidersa, Guangming Zhou, Joerg Rey, Francisco A. Hernández, Martin Lux, Georg SchlindweinKarlsruhe Institute of Technology (KIT), GermanyObjectives To (i) perform a proof-of-concept testing of a Prototypical Mock-Up (PMU) of the HCPB Fuel-breederPin with relevant manufacturing technologies under the HCPB operating conditions, and (ii) use theexperimental data to evaluate the PMU thermal-hydraulic performance (e.g. cooling capability) and tovalidate the CFD thermal-hydraulic calculations. The focus is on the annular gap (between tritium breeder and neutron multiplier) for the return flow andconsidering the possibility of enhancing the heat transfer by increasing the surface roughness. This poster presents: (i) the integration of the fuel-breeder Pin PMU into the HELOKA loop, (ii) the test matrix and the planned experimental campaigns, and (iii) the experimental results with focus on aspects relevant for the validation of the thermal-hydraulic design of the HCPB breeder zone. The experimental testing of the Pin PMU with the first insert (smooth surface roughness) was successfully completed in March 2022. In the next experimental campaigns, the second insert (with middle rough surface) and third insert (with high rough surface) will be tested. The previous Breeder Unit (BU) has two U-shaped cooling plates with many small cooling channels (5 × 3 mm2 cross sections), leading to a large pressuredrop and hence a large circulating power for the coolant; in addition to a lower efficiency of the power plant. In 2017, a new design of the BU, namely Fuel-breeder Pin, was introduced by the design team of the Helium Cooled Pebble Bed (HCPB) Breeding Blanket. The relevant analyses revealed that the Fuel-breeder Pin concept produced a pressure drop significantly lower than that produced by the previous BU design.This work has been carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No 101052200 — EUROfusion). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commissi n. Neither the European Union nor the European Commission can be held responsible for them.Experimental Results TC-1 to TC-8 are on outer / inner surface of Tube-4. TC-9 to TC-12 are on the outer surface of Tube-3. TC-13 to TC-16 are on the outer surface of Tube-2. TCs-17, 18, 19 are inside Tube-2 near the heaters. TC-20, TC-21 for helium inlet/outlet temperatures. TC-22, 23, 24, 25 are on the insulation surface.Fig. 1: The CAD design of the Fuel-breeder Pin Mock-up.532 mm≈ 2000 mmFeed-throughsfor TCsFlange-1Pipe-1Reducer-1Reducer-2Tee-junction-1Flange-2 Flange-3Feed-throughsfor heatersPipe-2Reducer-3 Elbow-1InsertPipe-2a (TC-21)Flange-4Support-1Pipe-1b (DP-1)Helium9 1011 1213 1415 1617 18 195 63 4871 2Tube-1Tube-2Tube-3Tube-422 2324 25InsulationTube-4Tube-3Tube-2Pressure MeasurementsExperimental Setup Temperature Measurements Absolute pressure sensor at the inlet of the mock-up. Differential pressure sensor to measure the pressure difference across inlet/outlet of the mock-up. Mass flow meter (consists of flow orifice, differential pressure sensor, absolute pressure sensor & TC).Mass Flow MeasurementPin Mock-upVacuum vesselConnection inlet pipeConnection outlet pipeInlet flangeOutlet flangeSupport structurePin Mock-up covered by thermal insulationOutlet pipeInlet pipeThermocouplesVacuum vesselSupport structureProtection cylinder The fuel-breeder pin PMU is tested in the Helium Loop Karlsruhe (HELOKA) facility that can provide the HCPB blanket-relevant conditions (helium at 300°C and 8 MPa pressure ). The PMU was installed in the HELOKA Test Section 1 vacuum vessel and connected with the loop pipes via 2 connection pipes (inlet & outlet). The design, manufacture and installation of the connection pipes were performed by an industrial contractor. The pipes were designed to withstand a helium pressure of 110 bar and helium temperature up to 550°C. After installing the mock-up, a leak test was performed for the connection flanges. The mass flow rate is calculated according to ISO 5167-1 from the measured pressure difference across a flow orifice and from the characteristics of the flowing helium. Helium density is determined using the measured absolute pressure and temperature.Fig. 6: Experimental values of Nusselt number (Nu) are compared with the correlations’ values. Fig. 3: Pin PMU after installing thermal insulation.Fig. 2: Pin PMU is installed inside vacuum vessel. Fig. 4: The numbers indicate the thermocouples locations.Case No.Mass flow rate [g/s]Heaters Power [W]Re118 - 195282900 -29702 7933 10594 13255 1592627 - 287924325 -46007 11898 15889 198710 23881137 - 3810565700 -606012 158613 211714 265015 31831646 - 4713207200 -740017 198218 264619 331220 3979Test Matrix It is planned to test the Pin PMU with three different inserts as follows: (i) insert 1 with hydraulically smooth surface, (ii) insert 2 with middle rough surface, and (iii) insert 3 with high rough surface.  Table 1 shows the test matrix implemented in testing the first insert. Each case was tested two times (2 runs). Figure 5 shows the assembly of the first insert with the other parts.Fig. 5: The first insert assembly. 0 2 4 6 8 10 12 14 16 18 20296298300302304306308310312314316 1st-run Inlet T 2nd-run Inlet T 1st-run Oulet T 2nd-run Outlet TTemperature (°C)Case number0 2 4 6 8 10 12 14 16 18 20 220,00,10,20,30,40,50,60,70,80,91,0 1st Run 2nd RunQ_Helium / Heaters PowerCase number2000 3000 4000 5000 6000 7000 800005101520253035404550Nusselt number (Nu)Reynolds number (Re) Experimental values Foust & Christian [1] McAdams [2] Davis [3] Wiegand [4]0 2 4 6 8 10 12 14 16 18 2078,078,579,079,580,080,581,081,582,0 1st Runs 2nd RunsPressure at mass flow meter (bar)Case number0 2 4 6 8 10 12 14 16 18 20 22294296298300302304306308310312314 1st Run 2nd RunTemperature at mass flow meter (°C)Case number0 200 400 600 800 1000 1200 1400 1600376380384388392396400404408412416420424428Insert 1 Run 20R: 63 g/s & 3979 WTemperature (°C)Time (s) TC-9 TC-10 TC-11 TC-12 TC-13 TC-14 TC-15 TC-16 TC-17 TC-18 TC-19Case 200 200 400 600 800 1000 1200 1400 1600296297298299300301302303304305306307308Insert 1 Run 20R: 63 g/s & 3979 WTemperature (°C)Time (s) TC-1 TC-2 TC-3 TC-4 TC-5 TC-6 TC-7 TC-8Case 20SOFT 2022Abstract #416Poster Session 3  The experimental Nusselt (Nu) values calculated from the experimental measurements and the relevant heat transfer equations are plotted versus the Reynolds (Re) numbers in Fig. 6. The Nu correlation by Davis [3] gives the best agreement with the experimental Nu values. Correlations by Wiegand [4] and McAdams [2] give lower values than the experimental ones.Experimental Nu Values vs. Correlations[1] Foust A.S., Christian G.A., “Non-boiling heat transfer coefficients in annuli”, American Institute of Chemical Eng. 36, p. 541-554, (1940). [2] McAdams W.H., Heat Transmissions 3rd ed., p. 241-244, (1954).[3] Davis E.S., “Heat transfer and pressure drop in annuli”, Transactions of ASME, p. 755-760, (1943).[4] Wiegand J.H. et al., “Discussion on annular heat transfer coefficients for turbulent flow”, American Institute of Chemical Eng. 41, p. 147-153, (1945).Fig. 12: Steady state temperatures of TC-9 to TC-19. Foust & Christian [1]:Nu = 0.04 a Re0.8 Pr0.4 / (a + 1)0.2a : annular diameter ratio.McAdams [2]:Nu = 0.03105 a0.15 (a - 1)0.2 Re0.8 Pr1/3 (μ / μw)0.14μw : viscosity at wall temperature.Davis [3]:Nu = 0.038 a0.15 (a - 1)0.2 Re0.8 Pr1/3 (μ / μw)0.14Wiegand [4]:Nu = 0.023 a0.45 Re0.8 Prn (μ / μw)0.14n = 0.2Fig. 11: Steady state temperatures of TC-1 to TC-8. Fig. 10: Pressure used for mass flow calculation.Fig. 9: Temperature used for mass flow calculation. Fig. 8: Heat absorbed by helium divided by heaters power. Fig. 7: The inlet and outlet helium temperatures.Table 1: Test matrix. 

Experimental thermal-hydraulic testing of a prototypical mock-up of the fuel-breeder pin concept for the EU-DEMO HCPB breeding blanket

https://publikationen.bibliothek.kit.edu/1000154508/150062216

Experimental thermal-hydraulic testing of a prototypical mock-up of the fuel-breeder pin concept for the EU-DEMO HCPB breeding blanket

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