Phase Change Cells. T. Shane Topham, Gail Bingham, Harry Latvakoski, Mike Watson

Transcription

1 Phase Change Cells T. Shane Topham, Gail Bingham, Harry Latvakoski, Mike Watson 1

2 Outline Phase change cell introduction Summary of ISS phase cell experiments Flight cell design improvements and ground test results 2

3 Need for Orbital Temperature Reference Phase transition cells for absolute temperature reference are key components of future climate monitoring missions Mission requirement: an SI-traceable standard for absolute spectrally resolved radiance in the infrared with high accuracy (0.1 K 3σ brightness temperature Each of the interferometers carry, on-orbit, phase transition cells for absolute temperature, with SI traceability [1]. Because temperature uncertainty will only be one of the contributors to the 0.1 K requirement, absolute temperature uncertainty will need to be lower, on the order of 0.01 K or better 3

4 Phase Transitions as Thermal References ITS90 Phase Change Materials T 90 /K t 90 / C Material State Uncertainty mk Traditional Triple Point of Water Cell Hg Triple pt 0.2(0.1) H 2 O Triple pt 0.05 (0.03) Ga Melt pt 0.2 (0.03) Large volume of PCM Long melt times Deep re-entrant wells Fragile containers Detailed manual heating and cooling procedures Practical absolute uncertainty, ~0.2 mk or better [2,3] 4

5 SDL Phase Change Program History VEGA Intl. approached to collaborate on gallium eutectic work Vega Results show Ga eutectics as viable PCMs for calibrations ESTO office begins funding support to speed development to benefit CLARREO with space qualification results Launch opportunities delayed by Russian Calibration Institute approvals with ties to VEGA Hardware returned on Soyuz to IBMP and then to SDL (2004) Initial internal studies of potential for NPOESS started (2006) SDL & IBMP agree to perform ISS testing of PCM cells. FY1 FY2 FY3 FY4 SDL IR&D program SDL starts IR&D program to get ISS tests with PCM cells and patent technology Hardware Launched on Soyuz, ISS experiments conducted 5

6 Mini Orbital Temperature Reference (MOTR) Flight 1 Experiment Design for ISS PCM temperature controlled by 2 TECs and a temperature-controlled heater enclosure Heat exhausted to cabin through forced ventilation Automated experiment data stored on CF card, removable only on ground Expanding bellow PCM container ~1 ml volume Re-entrant sensor well Sensor PCM TEC 6

7 Flight 1 Experiment Data Analysis 19 on-orbit melt curves Temperature calibration from bath post-flight Multiple similar data sets obtained prior to and after flight Use average in plotted window as melt curve temperature Temperature ( C) Flight Melt Curves smoothed to 2.2 minutes[4] Time from start of melt cycle (hrs) 7

8 MOTR Data Collection Timeline SDL Predelivery(1) 3 hr Melt Temperature Averages (C) Moscow Delivery SDL Predelivery SDL Predelivery (2) Moscow Delivery Moscow Pre-launch (1) Moscow Pre-launch (2) ISS Flight Moscow Postflight(1) Moscow Postflight(2) SDL Postflight Temp Trend(1) Temp Trend(2) SDL Post ReCal /10/2010 2/26/2011 9/14/2011 4/1/ /18/2012 5/6/ /22/2013 6/10/ /27/2014 Data Collection Date Moscow Pre-launch ISS Flight Moscow Post-flight SDL Postflight No continual drift trends observed over 4 years of melt data, indicating PCM contamination not a factor All data sets are within 6 mk. Individual point within a given set vary by < ±1.5 mk 8

9 Summary of All MOTR Data Sets All Data Sets Melt Temperature ( C) SDL Predelivery(1) SDL Predelivery (2) Moscow Delivery Moscow Pre-launch (1) Moscow Pre-launch (2) ISS Flight Moscow Postflight(1) Moscow Postflight(2) SDL Postflight Temp Trend(1) Temp Trend(2) SDL Post ReCal Melt Sequence Number ISS Data: Average Melt Temperature = C Standard Deviation = C ALL Data: Average Melt Temperature = C Standard Deviation = C Within ~0.6 mk 9

10 Orbital PCM Reference Value Criteria Stable, reliable PCM containment Miniaturized assembly Includes multiple PCMs to improve calibration knowledge Capable of reliably and repeatably freezing and melting PCMs Capable of accurately measuring temperature during melting to within 10 mk absolute error Capable of tracking blackbody temperature to within a few mk 10

11 Transfer of Calibration Calibration: During a recalibration the TEC is powered and the PCM is controlled to a different temperature than the thermal surface to melt the PCM. Temperature data collected during the melt allows recalibration of the PCM sensor. PCM Sensor TEC Thermal Surface (What you really want to measure) Transfer: When the TEC is not powered it acts as a thermal link to the thermal surface. If adequately insulated it will come to equilibrium with the thermal surface. The PCM sensor can be compared to thermal surface sensors readings.

12 Orbital 3 PCM Cell Design Phase-change cell with three cavities to be used for on-orbit temperature calibration Secondary cap (SS 304) Redundant welds contain PCM Threaded primary cap (SS 304) Phase-change material ~0.3 ml Thermistor Ga C GaSn C GaIn C Thermistor locator (Teflon) Cell body (SS 304) 12

13 Bath Bi-phase Equilibria Temperatures Gallium-Tin Calibration Bath Data Temperature, C PCM Freezing Cells PCM Melting Bi-phase Equilibrium Temperature PCM Avgerage Bi-Phase Equilibrium Temp ( C) Bi-phase Equilibrium Temperature for 3 Individual Cells Tested ( C) Ga , , GaSn , , Bath GaIn , , Time, hours Gallium bi-phase equilibria were within <1 mk of the ITS90 Ga fixed point at Most eutectic melt temperatures are reported to >10 mk absolute accuracies 13

14 SDL Vacuum Chamber Test Setup Circulated Liquid Cooled Base Outer Block Thermistor Inner Block Thermister Cell Mount Plate Surface Heater Block Isolator Copper Block PCM Cell Outer Rad Shield Inner Rad Shield TEC Vacuum Chamber Unpowered PCM Cells equilibrated to within 2.5 mk of Inner Block Thermistors at 24 C and at 1 C. Agrees with thermal model delta of ~2 mk equilibrium 14

15 Thermal Model of a Ga Melt Curve Condition: Blackbody at K Temp sensor between orange and red nodes Piece of the melting gallium Thermistor will read somewhere between these cell nodes 15

16 Gallium Gradients vs. Melt Time Gradients in cell and duration of melt vary with heating power applied. Mid-melt offsets in measurements agree with thermal model (~45-75 mk) 16

17 Ga Melt Point Repeatability TEC heating with constant current Copper block held at constant 8.5 ±0.01 C Melt durations very consistent Plateau mid-point repeatability ~2 mk 17

18 GaIn Melt Point Repeatability Melt durations varied by ~13% Inconsistency possibly due to small constant current variations in the TEC Mid-points group to ~5 mk Clear correlation between mid-point temperatures and melt durations 18

19 GaSn Melt Point Repeatability Melt durations varied by ~20% Inconsistency possibly due to small constant TEC variations Mid-points group to ~5 mk Clear correlation between mid-point temperatures and melt durations 19

20 Conclusions Orbital testing of Ga phase transitions showed no change in melt point under 0G conditions and verified long-term repeatability of melt curves SDL improvements of design include smaller cells and addition of two new melt temperatures for GaSn and GaIn eutectics SDL ground testing of cells with Ga and eutectics demonstrates 2-3 mk repeatability of three melt temperatures Ground testing and thermal modeling improve understanding of: thermal gradients within cells and their effect on interpretation of melt curves true bi-phase equilibrium temperatures of melt materials Questions? 20

21 References 1. Committee on Earth Science and Applications from Space: A community Assessment and Strategy (2007). Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, pp , ISBN Fluke Corporation,Hart Scientific Division, 5901 Series Triple Point of Water Cells 2005, [Revised 10/ D-EN-N Rev B]. 3. Mangum B. W. & Furukawa G. T. (Eds.). Guidelines for Realizing the International Temperature Scale of 1990 (ITS-90), NIST Technical Note 1265, August Topham T.S., Bingham G.E., Latvakoski H., etal., Observational study: microgravity testing of a phase-change reference on the International Space Station, npj Microgravity 1, Article number (2015), doi: /npjmgrav GE Sensing, Thermometric Ultrastable Probe Thermistors, SP series Datasheet, [copyright 2006]. 6. Heraeus, Platinum Resistance Temperature Detector, M 222 Datasheet, document name Index B, [June 2010]. 21

22 Additional Slides

23 Sealed Cells vs. Pressure Dependence of Fixed-Point For contamination issues PCM containers must be sealed 1 atm pressure changes melt temperature of water by 10 mk [3] Container must allow PCM expansion without changing fixedpoint temperature Flexible container: -No internal voids -PCM can expand container -PCM vacuum filled -complex filling -complex container -moving parts Rigid container: -PCM filled at 1 atm -Internal gas voids compress as PCM expands -location of voids in space?

24 SDL Temperature Sensor Testing Heraeus PRT and GE thermistor excellent size and long term stability [5,6] GE Thermistors tracked standards PRT ±3mK, with calibration improvement to ~1mK Heraeus PRTs tracked ±10-15mK (worse than larger wire PRTs) Heraeus shock resistance 40g at 10-2kHz Heraeus M222 PRT Drift 0.04% 1000hrs 2.1 x 2.3 mm (mk) GE SP60 Thermistor 1.5 mm 3.2 mm Drift 0.02% /yr Bath Cycling of 4 SP60 Thermistors

25 Ga Melts of Various Lengths 1-2 hour melt curves are ~50-60 mk higher than melt point at center of melt due to cell thermal gradients Agrees with thermal models which predict ~50-80mK. Longer melts within 5 mk of true melt temperature 25

26 GaSn Melts of Various Lengths 1-2 hour melts are only ~30-40 mk above eutectic melt point 26

27 GaIn Melts of Various Lengths 1 hour melts are 50 mk above eutectic melt point >5 hour melt was within 5 mk of eutectic melt point when it was stopped 27

28 Supercooling Behaviors Ga and eutectics cool below their melt points after reaching temperatures well above as liquids. 28

29 GaIn Behavior Improvements Tested in bath at slower ramp rates Ga rich mixture shows slightly less supercooling 29

30 Acknowledgements Russian Academy of Sciences IBMP for launch and flight support VNIIOFI (Andrey Burdakin) for Gallium eutectic investigations and preparation training NASA Earth Science and Technology Office (ESTO) for funding support NASA Langley s CLARREO team for CORSAIR work Questions? 30