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TFAWS Paper SessionDeCoM ValidationPresented ByDeepak Patel NASA/ Goddard Space Flight CenterThermal & Fluids Analysis WorkshopTFAWS 2011August 15-19, 2011NASA Langley Research CenterNewport News, VA

1Hume Peabody Matthew Garrison Dr. Jentung KuTamara O'Connell Thermal Engineering Branch at Goddard Space Flight CenterTFAWS 2011 August 15-19, 20112Acknowledgments OutlineIntroductionThermal Analysis ToolsAnalysis casesDeveloped/Exercised 1D computer codesDeCoM/EXCELTTHFloCADCompare 1D ResultsValidate against 2D Test CaseIntegrate into ATLAS Instrument ModelConclusionProblems Encountered/ Lessons LearnedSummaryFuture Work

TFAWS 2011 August 15-19, 201133Introduction:Thermal Analysis ToolsThermal Analysis is based on a Nodal Network SchemeThermal Desktop (TD): Used for View Factors and Environmental heat calculations. A GUI (Graphical User Interface) for GMM (Geometric Math Model).Also generates SINDA (System Improved Numerical Differencing Analyzer) construct logicsFloCAD: GUI for FLUINT (Fluid Integrator) constructs.

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TFAWS 2011 August 15-19, 20114Introduction:Analysis Cases1D RadiatorSimilar area to ATLAS radiator model in Thermal Desktop (TD)1D Condenser (1D Flow)Length: 372in , Diameter: Steady state conditions, constant mass flowrate Ammonia as working fluidEnvironmentRadiative Tsink = -80CLimitationsSingle condenser lineNo evaporator/CC modeled Short condenser nodes (2 Nodes)Analysis Cases & Calculated % Area margin5Power (W)Saturation Temperature (oC)Calculated Area (in^2)ATLAS Radiator Area (in^2)% Area Margin216 -41907223215.0216161314223241.014223767223266.0ATLAS Laser Scenarios

6 inRadiatorCondenser372 in

ATLAS Radiator:The routing and the radiator are represented, in order to create a simplified 1D model (as shown below)**Cases developed for test-bed/development purposes not design5

OutlineIntroductionDeveloped/Exercised 1D computer codesDeCoMTTHFloCADCompare 1D ResultsValidate against 2D Test CaseIntegrate into ATLAS Instrument ModelConclusionProblems Encountered/ Lessons LearnedSummaryFuture Work6TFAWS 2011 August 15-19, 2011

6EXCEL/DeCoM Implementation EXCEL implementationCalculate LHP condenser performance off-line using boundary conditions similar to those from the 1D analysis cases.Project GLAS (GeoScience Laser Altimeter System) had predicted its condenser results based on EXCEL analysis similar to the one in this implementation.Tested for steady state results only.For multiple iterations, manual input is required.

DeCoM (Deepak Condenser Model) implementationCode based on FORTRAN language. Model works for transient and steady state conditionsSteady state results are produced, to compare against 1D EXCEL model.Calculate condenser fluid quality, temperature values, and fluid wall convection value.Radiator and wall temperatures are calculated by SINDA.Input DeCoM in VAR 1 of SINDA, in order for the logic to be executed at every time step.7**Equations based on Governing Theory from previous slides.TFAWS 2011 August 15-19, 201178 DeCoM/EXCEL InternalThe above diagram shows the network of nodes in the solution (code).

EXCEL/DeCoM Implementation: Nodal Network Nodal NetworkFluid Boundary NodesRadiator NodesWall NodesFluid Wall ConductorThese temperatures and conductor values are calculated by EXCEL/DeCoMWall Rad ConductorTFAWS 2011 August 15-19, 20118EXCEL/DeCoM Implementation: Calculations Flow Chart9TFAWS 2011 August 15-19, 2011

2-Phase Fluid

Subcooled Liquid

Solve for, i (as shown in Equation Slides)

YESNOInitial Conditionsi= 1 , N Read Input ValuesDetermine Fluid StageCalculate Fluid to Wall Heat Transfer ValueCalculate Fluid ParametersOutput Fluid Parameters

9TTH (Triem T. Hoang) Implementation TTH DescriptionNASA SBIR (Small Business Innovation Research) task development softwareA LHP system solver (CC, Evap, Cond, L/V Lines). Compiled library for use in SINDA. Appropriate for transient and steady state casesTTH condenser is part of an overall LHP model code. Condenser section of the code was called as a subroutine for specific computations. Independently of other components.

ImplementationUsed as a validation tool against EXCEL/DeCoM implementation.Output steady state results only.Restricted to steady state in order to compare with EXCEL implementation.Calculates fluid temperatures, quality and heat transfer value between fluid and wall. SINDA calculates radiator temperatures.10TFAWS 2011 August 15-19, 201110FloCAD Implementation 11FloCADFloCAD with FLUINT calculates entire network with fluid nodes, wall nodes, and radiator nodes as one network. DeCoM calculates fluid node parameters based on wall node conditions (which are based on radiator nodes)Third data point for comparison to TTH & EXCEL/DeCoM Implementations for 1D.ImplementationInitial and boundary conditions similar to DeCoM/EXCEL and TTH.Lockhart-Martinelli correlation option used

PlenumSTUBEMFRSETJunctionTIEWall nodeConductorThermal Desktop FloCAD networkRadiator node

Fluid nodeTFAWS 2011 August 15-19, 201111IntroductionDevelop/Exercise 1D Computer CodesDeCoMTTHFloCADCompare 1D ResultsValidate against 2D Test CaseIntegrate into ATLAS Instrument ModelConclusionProblems Encountered/ Lessons LearnedSummaryFuture Work

Outline12TFAWS 2011 August 15-19, 2011

12Tsat = -4 CPower = 216 WTsat = 16CPower = 216 WTsat = 23CPower = 142 W13Results and Comparison 1D:Analysis Case

RadiatorCondenser1DATLAS RadiatorATLAS Radiator:The routing and the radiator is represented, in order to create a simplified 1D model (as shown adjacently)(ATLAS radiator was unfolded with the condenser to create a 1D model )TFAWS 2011 August 15-19, 201113

Results and Comparison 1D:Quality Vs. Temperature (Tsat = -4 C) 14TFAWS 2011 August 15-19, 201114Results and Comparison 1D:Quality Vs. Temperature (Tsat = 16 C) 15TFAWS 2011 August 15-19, 2011

DeCoM 16 TLDeCoM 16 XL15

Results and Comparison 1D: Quality Vs. Temperature (Tsat = 23 C) 16FloCAD/DeCoM/EXCEL have similar resultsTFAWS 2011 August 15-19, 201116

Log Scale of G value comparison between DeCoM and TTH

TFAWS 2011 August 15-19, 201117h (W/m2K)HX1LEG()x, qualityh (W/m2K) -> G (W/K)SINDAG values printed out from TTH LHP Condenser functions.Results and Comparison 1D: TTH JustificationPIPE2P routinePIPE2P routinex, qualityResults and Comparison 1D: Summary18The hand calculated length is an estimate at which all input power would be rejected.

DeCoM/EXCEL and FloCAD results are close to hand calcs in comparison to TTH condenser method.

Results show that TTH condenses much earlier than other methods.TTH code calculates the quality based on a G value from empirical data (6000 W/m2K, for Vapor).DeCoM and FloCAD calculate the quality based on a G value from the Lockhart-Martinelli correlation.

FloCAD seems to use more CPU time.DTIMEF chosen by SINDAUser must be familiar with run settings, in order to decrease the CPU time. Once the modifications were made, CPU time was ~8.0 seconds. DeCoM method is both accurate and fast.TFAWS 2011 August 15-19, 2011ImplementationPower (W)Tsat (C)CPU Time (sec)Condensation Length (in)Hand Calc216-4N/A309DECOM7.0312FloCAD30.0285TTH Condenser8.0197Hand Calc21616N/A213DECOM7.0220FloCAD26.0201TTH Condenser6.0108Hand Calc14223N/A124DECOM11.0130FloCAD7200.0 (8.0)*119TTH Condenser13.05218OutlineIntroductionDeveloped/Exercised 1D computer codesDeCoMTTHFloCADCompare 1D ResultsValidate against 2D Test CaseIntegrate into ATLAS Instrument ModelConclusionProblems Encountered/ Lessons LearnedSummaryFuture Work19TFAWS 2011 August 15-19, 2011

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GLAS DM LHP20GLAS DM LHP Test Case

Thermal Desktop Model4831OD=0.127Fluid = Propylene

Wall to Radiator I/F:Width = , NuSilTest # Power(W)Tsat (oC)Tsink(oC) 11206.5-100.021247.2-100.01/8 Al radiator3 mil Kapton on front and blankets on back.Model Correlation 2D: GLAS LHP Test Case & SetupNOTE: Test values, and its results have been extracted from the document: GLAS Final Test Report of DM LHP TV TestingTemperature sensor location (data point from which TLL was measured.) Liquid LineTFAWS 2011 August 15-19, 201120Twall = -86.84 Cw/ 0.125 thickness21DeCoM implementationApproximate length of the condenser was used, based on scaling, as shown in previous slide.Liquid line was also approximated to be starting from the TLL sensor Location. Only the condenser outlet temperature was compared, due to the lack of temp. sensor data.Test data vs. DeCoM : steady state resultsmFLOW*Cp*Tavg equates to ~1.9W, which may be the result of parasitic heat leak from the system. (1.9W is the amount of subcooling greater then the test data)Modified power shows the temperature differences are less then a 1C.Possible factors for this heat leak, resulting in power/temperature differencesMechanical support structure.Transport lines insulation (modeled assumed to be perfectly insulated)

GLAS Condenser Test Results vs. DeCoM ResultsPower (W)Tsat (C)Tsink (C)TEST LL TEMP (C)DeCoM LL TEMP (C)1206.5-100.0-23.0-20.491247.2-100.0-20.0-17.38Model Correlation 2D: ResultsTavg = ~2.6CModified (W) oC(118) -22.23(122) -19.05TFAWS 2011 August 15-19, 201121OutlineIntroductionDeveloped/Exercised 1D computer codesDeCoMTTHFloCADCompare 1D ResultsValidate against 2D Test CaseIntegrate into ATLAS Instrument ModelConclusionProblems Encountered/ Lessons LearnedSummaryFuture Work22TFAWS 2011 August 15-19, 201122Requirements for ATLAS model integrationSource code available for distribution and/or modificationMust not be detrimental to model runtime. Method validated against test data and hand calculations. Selected methodTTH is not easily distributable or modifiable. Based on the work performed (explicitly for condenser, and 1D model) further validation of the condenser subroutine is required. FloCAD take longer to calculate.If model is not well configured, it may take longer, else the difference is shown in previous 1D analysis slide.One of the drawbacks, is that it requires a licenseDeCoM is distributable, accurate and fast.

Therefore, DeCoM was chosen to be used as the code to predict the ATLAS laser radiator performance.23Integrate into ATLAS Instrument Model:Method SelectionTFAWS 2011 August 15-19, 20112324ATLAS radiator thermal designSize the radiator (Lowest TLaser, Highest QLaser, Hot Environment)Size the radiator heater (Highest/Lowest QLaser , Cold Environments) Heater is sized to prevent condenser fluid from freezing.Integrate into ATLAS Instrument Model:Method Integration

Condenser lineRadiatorInletOutletNuSil I/F between pipe and radiator.** Condenser routing is preliminary39.368.7Al HC PanelCond L = 325, OD = 2 x 2 NodesTFAWS 2011 August 15-19, 20112425

Integrate into ATLAS Instrument Model:Temperature MapsTest Case: -4 C / 212 WLowest TLaser, highest QLaser Hot Beta 0oCurrently no gradient requirements are set. Temperature maps are produced for STOP analysis purposes.Orbit DayOrbit Shadow ExitTemperature, C

A1A

A1A2A

Subcooling cancelation occurs when some amount of heat leaks from the vicinity of 2-phase into subcooling region. Points on the maps, represent phase change (A,A) and subcooling cancelation (1A,2A, 1A) locations. Points are graphically represented in the next slides.2526Integrate into ATLAS Instrument Model:Quality vs. Temperature (TSAT = -4.0 C , 212W)

A1A2AA1A Radiator experiences both shadow and day environments in HB00 orbit. (below is the graphical representation of HB00 orbit)

Shadow (OS)Day (OD)VehicleTFAWS 2011 August 15-19, 20112627

B1B2B3BIntegrate into ATLAS Instrument Model:Quality vs. Temperature (TSAT = 16.0 C , 212W)Highest QLaser , CB90 for cold environments.Subcooling cancelation points occur due to heat leak from the adjoining 2-Phase section of the condenser line.Condenser Length (in)

B2B1B3BTFAWS 2011 August 15-19, 20112728

C1C2CIntegrate into ATLAS Instrument Model:Quality vs. Temperature (TSAT = 23.0 C , 142W)Lowest QLaser ,CB90 for cold environments.2-phase section for this case is minimal, therefore the subcooling temperature increases significantly (at noted locations) Condenser Length (in)

C1C2CTFAWS 2011 August 15-19, 20112829ATLAS Radiator Heat Data Tabular data shows that physics of the radiator is satisfied. All energy is balanced.2P power does not match the input powerIn a phase change (2P to liquid), some amount of heat from liquid phase (node) is leaked back into the 2P (node), and there is a decrease or increase in 2P power depending on the direction of the leak. Integrate into ATLAS Instrument Model:Radiator Heat Imbalance( - ) Heat Leaving Radiator( + ) Heat Entering RadiatorT-4C (Orbit Shadow Exit) 212WHB00T-4C (Orbit Day) 212WCondenser2P (two-phase)212WCondenser2P210WSubcooled Liquid21WSubcooled Liquid15WATLAS8WATLAS2WSAP338WSAP363WSC Backload7WSC Backload7WSPACE-585WSPACE-596WHeat Imbalance0WHeat Imbalance0WT16C 212W (CB90)T23C 142W (CB90)Condenser2P220WCondenser2P147WSubcooled Liquid45WSubcooled Liquid42WATLAS3WATLAS5WSAP346WSAP272WSC Backload0WSC Backload0WSPACE-615WSPACE-466WHeat Imbalance0WHeat Imbalance0WSolar, Albedo, Planet ShineTFAWS 2011 August 15-19, 201129DeCoM integration into ATLASThe CPU time difference of before and after the Code integration was negligible, difference is less then 1sec.ResultsMinimum liquid line temperatureResults help size the radiator heater power required in order to keep ammonia from freezing.The last column in the table indicates an approximate amount of heat rejected to the radiator in the subcooled phase.

30Temperature CaseLiquid Line Temperature (oC)Q (W)-4.0 C (least condensed)-32.0021.00-4.0 C (most condensed)-24.0015.0016.0 C-39.0046.0023.0 C-60.0048.00Integrate into ATLAS Instrument Model:SummaryTFAWS 2011 August 15-19, 201130OutlineIntroductionDeveloped/Exercised 1D computer codesDeCoMTTHFloCADCompare 1D ResultsValidate against 2D Test CaseIntegrate into ATLAS Instrument ModelConclusionProblems Encountered/ Lessons LearnedSummaryFuture Work31TFAWS 2011 August 15-19, 201131Problems Encountered / Lessons LearnedDeCoM / EXCELProperty calculations in EXCEL differed from DeCoMProperty vs. temperature plots had to be generated to obtain equation of the lines. Radiator temperatures were modeled as wall temperatures.Had to create iterative equations to calculate radiator temperatures.Reading Thermal Desktop valuesReading/editing node temperatures, conductor heat rates, and modify the conductance values, was learned.Printing quality and temperature valuesA WRITE statement (FORTRAN Language) was implemented. Temperature and quality results did not match EXCELEXCEL property Vs. temperature plot equations were applied to the code.

FORTRAN programming language was learned from this exercise. 32TFAWS 2011 August 15-19, 20113233TTH Problems EncounteredIntegrating with the Thermal Desktop modelFull understanding of the softwares limitations was required.A library file was inserted to call condenser subroutine for fluid calculationsFloCAD Problems EncounteredNodal Network was unclearAn understanding of tanks and plenums was required.Correlation method similar to that of EXCEL and FORTRANParameter to call the Lockhart-Martinelli method had to be appliedCPU time usage was too high (as shown in the 1D results slide)User input is required, and must be familiar with run settings in order to decrease the CPU time. Problems Encountered / Lessons LearnedTFAWS 2011 August 15-19, 20113334SummaryUnderstand and develop a condenser Model set of equationsCompare three possible solution methods for a 1D simplified radiator and condenser (1D flow).Correlate the DeCoM method against test data from GLAS LHP.Implement the DeCoM into ATLAS thermal model and provide radiator temperature predictions. TFAWS 2011 August 15-19, 201134Future WorkDeCoM Future PossibilitiesPackage the code as a subroutine.Including user manual for use on other projects.Better integration with generic SINDA models.Return of USER requested internal Parameters. (e.g. quality) Allow user defined node lengths (currently only 2)Investigate DeCoMs response to quick transient changes in environment or due to loadCheck validity of FloCAD and TTH against the 2D test case. Correlation against various other LHP test data, will validate the method even further, making it more reliable. Properties other then Ammonia needs to be built-into the code. Alternate correlation schemes to Lockhart-MartinelliIntegrate option for multiple condenser lines35TFAWS 2011 August 15-19, 201135

36Condenser effects on the RadiatorEnjoy this small clip of DeCoM in its workings.TFAWS 2011 August 15-19, 201136BACKUPSymbols & Acronyms37Subscripts

Superscripts

AcronymsSINDA: Systems Improved Numerical Differencing Analyzer)FLUINT: Fluid Integrator)SC:SubCooledLL:Liquid LineLHP:Loop Heat PipeSTOP:Structural-Thermal-Optical PerformanceTFAWS 2011 August 15-19, 201137