PowerPoint Presentation

Modeling and Analysis of a Heat Transport Transient Test Facility for Space Nuclear SystemsAdam WheelerDepartment of Nuclear Engineering & Radiation Health PhysicsOregon State University

March 20, 2013

OutlineIntroductionReference designVariations from the Reference DesignModeling programsSolidWorksSTELLAModelsGoalsAssumptionsResults from analysisDiscussion of resultsConclusion and future workReferences

IntroductionObjective: Develop and analyze a test facility based on a 1 to 10kWe heat-pipe cooled space nuclear reactorGoals: Design a feasible test facilityPredict steady state performance Predict transient responses Method: Use a lumped parameter model and a 3D CAD simulation program for analysisReference DesignReference system is a 1 to 10kWe reactor moduleDeveloped by a collaboration between NASA Glenn and Marshall Research Centers and Los Alamos National Laboratory

Newest Rendition of the Reference DesignHeat pipes on the outside of the reflector instead of in the coreOr heat pipes between the reflector and the fuelConductive material based radiator with heat pipe bands on the inside to spread the heat load

Variations from the Reference DesignOriginal Design1000K sodium heat pipes in core8 to 16 heat pipes from core to power convertors

Pin or plate fuel interface to heat pipesDirect energy conversion via Stirling engines or ThermoelectricsCone-shaped radiator arrayTest Facility423 to 600K water heat pipes in core simulator8 heat pipes between core & power convertor simulatorsStainless steel cylinder interface to heat pipesPower conversion thermal absorption simulator

Cylindrical radiator arrayHeat Pipe Data

Water Heat Pipe Limits

Limits to the SystemModeling ProgramsSolidWorksUsed for 3D rendering and various types of simulationsFlow Simulation package allows for heat and fluid flow in a time dependent simulationLacks computational stability and speed but can give very detailed resultsSTELLAObject oriented flow based systemGreat for modeling the transfer of some item (heat, chemicals, water, population, etc.) to another location through timeLacks accuracy and detail but is very versatile and fast(STELLA can be made more accurate but quickly reaches a diminishing return in effort and time which makes more complex programs such as STAR-CCM and FLUENT more attractive)

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SolidWorks Model Boundary ConditionsTo simulate the affects of convection, a direct heat sink boundary condition was applied which simplified the modelA heat source was placed in the core simulators heater rodsTo model the heat pipes, a custom material with very high conductance at the heat pipes operating temperatures was used along with the heat pipe operator in Flow SimulationRadiation transfer boundary conditions were placed on the outer surfaces of the model

ECSFlow Simulation Interface

Stella ModelAssumptionsAxial heat transfer is negligible in comparison to radial heat transferHeat transfer to and from sinks and sources can be done with 1D radial methodsAdiabatic boundary conditions assumed for outer edges of the system

Stella ModelCore Simulator Cross-sectionEnergy Conversion Simulator Cross-sectionSTELLA ModelSTELLA model uses three basic componentsConvertorUsed to control flow and system variables ReservoirPoints for collecting the heat passing through systemBidirectional flowForces directional flow between Reservoirs and Controlled by connections between Convertors and ReservoirsSTELLA Model

STELLA ModelThe whole thing:

Scenarios AnalyzedStartupSTELLA and SolidWorks In-Depth DiscussionOne Core Heat Pipe LostSTELLA and SolidWorks In-Depth DiscussionStaggered Core Heat Pipes LostSolidWorks Only, In-Depth DiscussionOne Bank of Radiator Heat Pipes LostSolidWorks Only, In-Depth DiscussionTwo Core Heat Pipes LostSTELLA and SolidWorks, Brief OverviewThree Core Heat Pipes LostSolidWorks only, Brief OverviewOpposite Core Heat Pipes LostSolidWorks only, Brief OverviewOne Absorber LostSolidWorks only, Brief OverviewOne Radiator Heat Pipe LostSTELLA and SolidWorks, Brief OverviewSTELLA Results: Startup Core Heat Pipes

STELLA Results: Startup Radiator Heat Pipes

SolidWorks Results: Startup Core Heat Pipes

CoreSolidWorks Results: Startup Radiator Heat Pipes

Radiator

ECSSTELLA Results: One Core HP Lost

STELLA Results: One Core HP Lost

SolidWorks Results: One Core HP Lost

SolidWorks Results: One Core HP Lost

SolidWorks Results: One Core HP Lost

Core

ECSSolidWorks Results: One Core HP Lost

RadiatorSystemSTELLA ComparisonsStartupOne Core Heat Pipe LostTwo Core Heat Pipes LostContinue the trend of startup and one core heat pipe lost scenariosOne Radiator Heat Pipe LostShowed the same trend as previous comparisons

(all scenarios were run with STELLA and the trends stayed constant throughout, but there is not enough time or room to speak on all of them)SolidWorks Results: Staggered Heat Pipes Lost

Core

ECSSolidWorks Results: Staggered Heat Pipes LostSolidWorks Results: Four Radiator Heat Pipes Lost

Core

ECSSolidWorks Results: Four Radiator Heat Pipes Lost

Radiator

SolidWorks Results: Two Core Heat Pipes Lost

CoreECSRadiatorSystem

SolidWorks Results: Three Core Heat Pipes Lost

CoreECSRadiatorSystem

SolidWorks Results: Opposite Core Heat Pipes Lost

CoreECSRadiatorSystemSolidWorks Results: One Absorber Lost

CoreECSSolidWorks Results: One Absorber Lost

RadiatorSystem

SolidWorks Results: One Radiator Heat Pipe Lost

CoreECSRadiatorSystemDiscussion of ResultsSTELLA:System is fast in responding to heat transientsTemperature changes as a result of heat pipe losses are less then 100 KThe changes in temperatures in comparison to SolidWorks are off by as much as 40 KStartup steady state is 40 K less than SolidWorksSolidWorks:Reasonably agrees with the STELLA time changes, and shows in greater detail and accuracy the temperature differences across the systemDiscussion of Results

ConclusionFuture WorkFuture work:Increasing accuracy in STELLA modelExact design specificationsCost of actually building the facilityGravity scalingFinding a functional variable heat absorption methodModel the facility using different programs to get more accurate results (STAR-CCM, FLUENT, etc.) References