Diez d.l. Rios Ramos, N.

Hering, W.

Onea, A.

Perez-Martin, S.

Stieglitz, R.

English

KITopen

KIT – The Research University in the Helmholtz AssociationInstitute for Neutron Physics and Reactor Technologywww.kit.eduNumerical investigations of temperature distribution in an AMTEC test cell and comparison with experimental dataA. Onea, W. Hering, S. Perez-Martin, N. Diez d.l. Rios Ramos, R. Stieglitz11th PAMIR International Conference, July 1 – 5, 2019, Reims, France2 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyOutlineIntroductionAMTEC test cellNumerical model (ANSYS CFX)Numerical results and comparison with experimental dataConclusions3 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyIntroductionCSP concept* of  solar tower plant with Na as HTF and AMTEC technology as topping cycle  R&D on materials and componentsCSP & AMTEC system for SEP***W. Hering et al. – Europ. Ph. J.  33, 03003 (2012)** Hering et al., PAMIR 2016***N. Diez, PhD KIT, 2018***Developed in the frame of the Helmholtz Energy Material Characterization Platform (HEMCP) and Helmholtz Alliance on Liquid Metal Technology (LIMTECH) ATEFA (AMTEC TEst FAcility)*** successfully operated up to 700°C -> experimental data (T) availablePrimary mirrorSecondarymirrorReceiver4 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyMotivationCFD model: Only one study reported so far#Development of a CFD model for AMTEC cell - thermodynamics- thermal radiation in sodium vapor - (later): sodium condensation model- (later): electrical modelValidation of CFD data with the experimental data from ATEFAStudies for AMTEC power improvementDecrease parasitic losses (thermal radiation)Investigation of new cell configurationsModels for calculation of AMTECThermal model*Electric model** (2D)* Tournier et al. – CONF 970115 (1997)** Tournier, El-Genk – J.A.Electrochem. 29 (1999)*** Tournier, El-Genk – JTHT 13 (1999)# Lee et al., HMT 53 (2017)Pressure loss model***Electrochemical model***5 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyAMTEC (Alkali metal-to-energy converter)Heinzel et al., KEM 59, 1991 Flat temperature profile withabrupt fall at the condenser wall due to condensation6 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyAMTEC test cellInstrumentation: Type K thermocouples (up to 1000°C)- BASE: max. error: ± 3.5 °C- Condenser: max. error: ± 3.7 °C7 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of Technology- No sodium condensation- Location of the inner BASE/feedthroughs and cooling system implemented as “best approximate”Numerical model (ANSYS CFX)*P. Breton - 3rd S.M. Sodium/fuel interaction FR ,1976** F. Richter - The Physical Properties of SteelsNa inletNa outletBASE: solid domain, CC: porous and solid domains, sodium side: vapor, condenser: solid domain (SS), air: gasGrid: ~ 5.3 Mio cells (Hexa: ~2 Mio., Tetra ~2.6 Mio)Na vapor (data from SAS-SFR*) defined as gas/steam with temperature dependent propertiesAir properties implemented as temperature dependentSteel specific heat capacity and thermal conductivity as temperature dependent** Na: laminar flow, MFR = 1 g/hAir: turbulent flow (SST TM), Re number: ~3300Temperature field at BASE implemented from experimental data from ATEFA8 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyNumerical model (ANSYS CFX)Heat transfer by radiation and conduction dominant vs. convective HTAll inner surfaces considered gray and diffuseHeat transfer: Thermal energy modelMonte Carlo radiation modelSpectral model: GrayScattering model: isotropicHistories: 100000-500000Components (walls, ceramic) emissivities implemented from literatureas temperature dependentSodium vapor radiation data (absorption, scattering) from Hattori et al.Surfaces: diffuse emittersImbalances << 1 %Residuals: ~ 10-4 - 10-59 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyNumerical resultsTemperature distribution along the height of the condenserTE SN04 SN06 SN07 SN08 SN10 SN11 SN10ASN10BExp. 197 167.1 166.7 161.6 151.6 138.1 181.1 213.3CFD 220.3 196.4 180.7 165.7 164.5 163.1 186.9 214.9PD[%] 11.8 17.5 8.4 2.5 8.5 18.1 3.2 1TE SN04 SN06 SN07 SN08 SN10 SN11 SN10ASN10BExp. 222 176.1 174.8 175.8 163.6 137.8 206.6 236.3CFD 207.9 209.9 198.3 186 184.2 185.6 203 242PD[%] 6.3 19.1 13.4 5.8 12.6 34.7 1.7 2.4TBASE = 500°CTBASE = 600°C*N. Diez, PhD KIT, 20185mm 10mm10 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyTemperature distributionTBASE = 500°C TBASE = 600°C11 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyTemperature distribution in the cellLinear temperature decrease in the vapor domain, but notemperature decay at the wallSignificantly lower temperature in the current collector (meshin CC and flow)Good agreement between experiment and numerical modelin the bulk vapor regionZ[m]0.1150.080.0612 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyAxial temperature distributionThe pattern of the axial temperature distribution at the BASE is extendingthrough the BASE-condenser space (quasi no convective effect)The pattern is continuously smoothed while approaching the wall -> discontinuous sodium film occuring on the condenser wallSignificant influence of the CC and current feedthroughs on temperatureTBASE = 500°C TBASE = 600°C13 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyVelocity field in Na and airTBASE = 500°C TBASE = 600°CTBASE = 600°C14 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyConclusionsCFD model developed for sodium vapor flow considering thermal radiation within an AMTEC cellGood agreement obtained between experimental data and numericaldata in the bulk vapor domain.CFD model overpredicts up to 20% the experimental data observed at the condenser due to the lack of consideration of a sodiumcondensation model in the numerical approach and to the fact that theposition of the inner cell and of the cooling system are „bestapproximate“The differences observed at the wall are not constant, due to the factthat the condensation film is probably disrupted and not uniformThe sodium temperature distribution in the vapor has a linear decay upto the condenserThe current collector and current feedthroughs have a significantinfluence on the temperature profile in the BASE-condenser region15 Institute for Neutron Physics and Reactor TechnologyKarlsruhe Institute of TechnologyThank you for your attention!

Numerical investigations of temperature distribution in an AMTEC test cell and comparison with experimental data

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Numerical investigations of temperature distribution in an AMTEC test cell and comparison with experimental data

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