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X-Ray Calorimeter ~ Concept Presentation ~

X-Ray Calorimeter ~ Concept Presentation ~. Thermal Mike Choi February 17, 2012. Power Dissipation*. *Edit Grid. ^ I f the MEB is operating during standby mode, it consumes 36W and can be subtracted from heater needs one-for-one. Power Dissipation*.

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X-Ray Calorimeter ~ Concept Presentation ~

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  1. X-Ray Calorimeter ~ Concept Presentation ~ Thermal Mike Choi February 17, 2012

  2. Power Dissipation* *Edit Grid ^If the MEB is operating during standby mode, it consumes 36W and can be subtracted from heater needs one-for-one.

  3. Power Dissipation* *30% margin added, except cryocooler, for thermal analysis ^If the MEB is operating during standby mode, it consumes 36W and can be subtracted from heater needs one-for-one.

  4. Temperature Requirements

  5. Orbit Thermal Environment • L2 provides excellent thermal environment for passive (radiative) cooling • Earthshine and moonshine negligible • Thermal disturbances • Sun angle changes due to ±20º roll and ±45º pitch • Seasonal variation of solar irridiance • Charged particles environment requires electrically conductive thermal coatings

  6. Thermal Design Concept All Components Enclosed in MLI Enclosure which shades components from sunlight Separate Sunshield Supported by Mechanical Structure Not Needed Because There Is No Passive Cooling Radiator for Cold Detectors (e.g., IXO XGS CCDs Required -80ºC) Low absorptance and Emittance Coating on MLI Outer Cover Minimizes Effect of Sunlight (MLI Includes a Kevlar Layer for Micrometeoroid Protection) Heat Pipes Transfer Heat from Components to Radiators Electronics Boxes Thermally Isolated from Equipment Deck *ADR CE and CFEE Require ±1˚C Stability

  7. Thermal Model -- Radiator Locations CCHP Evaporator Below Condenser -- Reflux Mode Cryocooler Radiator E-Box Radiator E-Box Radiator ADR CE and CFEE Radiator S/C is notional 1 g in ground testing CCHP: constant conductance heat pipe

  8. Thermal Model -- Radiator Locations Cryocooler Radiator MLI Enclosure E-Box Radiator ADR CE and CFEE Radiator MLI Enclosure

  9. Thermal Block Diagram NS43G Paint NS43G Paint NS43G Paint EB Radiator Cryocooler Radiator ADR CE Radiator CCHPs (Ammonia) CCHPs (Ammonia) CCHPs (Ammonia) CCHPs (Ammonia) CCHPs (Ammonia) 209 W (Peak Power Mode) CCHPs (Ammonia) 363 W (Peak Power Mode) 298 W (Peak Power Mode) Cryostat Shields Motor Mount Cold Head Cryocooler Compressor ADR Control E-Box CFEE Harness Cryocooler Control E-Box DEEP MEB Harness Operating Mode Heaters Survival Heaters

  10. Heat Pipe Selection • Constant conductance heat pipes (CCHP) transport heat from cryocooler compressor motor mount and electronics boxes to radiators • Loop heat pipe (LHP) is not considered although it reduces survival heater power significantly and does not gravity issue in ground testing because of following reasons • LHP is expensive (~$106); CCHP is less expensive (~$104) • L2 orbit provides a stable thermal environment for radiators on anti-sun side • CCHP has redundancy

  11. Thermal Coating Selection • Electrically conductive thermal control coatings have flight heritage • Radiators have NS43G yellow paint which has a high emittance (0.9) • Flown on WIND, POLAR, MAP, etc. • Radiators not exposed to sunlight so that solar absorptance is not a factor • MLI outer covers exposed to sunlight have silver conductive composite coating (ITO/SiOx/Al2O3/Ag) which has a low absorptance (0.08 at BOL) and high emittance (0.6) • Flown on WIND, IMAGE, FastSat, etc.;

  12. Operational Heaters • Operational heaters and thermostats attached to exterior of cryocooler compressor motor mount • Set point of primary heater circuit thermostats is 6ºC open/3ºC closed • Set point of redundant heater circuit thermostats is 3ºC open/0ºC closed • Operational heaters and thermostats attached to exterior of electronics boxes (except ADR CE and CFEE) and filter wheel mechanism • Set point of primary heater circuit thermostats is -4ºC open/-7ºC closed • Set point of redundant heater circuit thermostats is -7ºC open/-10ºC closed • Operational heaters and thermistors attached to exterior of ADR CE and CFEE • Primary heaters controlled by proportional or PID controller to 29ºC±0.25ºC • Redundant heaters set point is 0.5ºC lower

  13. Survival Heaters • Survival heaters and thermostats attached to exterior of cryocooler compressor motor mount • Set point of primary heater circuit thermostats is -44ºC open/-47ºC closed • Set point of redundant heater circuit thermostats is -47ºC open/ -50ºC closed • Survival heaters and thermostats attached to exterior of electronics boxes, including ADR CE and FEE, and filter wheel mechanism • Set point of primary heater circuit thermostats is -24ºC open/-27ºC closed, except for filter wheel mechanism • Set point of redundant heater circuit thermostats is -27ºC open/ -30ºC closed, except for filter wheel mechanism • For filter wheel mechanism, set point of primary heater circuit thermostats is -9ºC open/-12ºC closed, except • For filter wheel mechanism, set of redundant heater circuit thermostats is -12ºC open/-15ºC closed

  14. CCHP to Cryocooler and Radiator Interfaces Radiator Spreader CCHPs To Top of Cryocooler Hot Side To Bottom of Cryocooler Hot Side CryocoolerMotor Mount (~20 cm x ~20 cm) 1. Heat Transport Capacity of This Concept is Doubled from Single Evaporator Design. 2. Redundant CCHP Not Shown. 3. Actual bends of CCHP will not be as sharp as shown.

  15. Radiator Sizes 1.0005 m2 0.7888 m2 0.6324 m2

  16. Temperature Predictions *Operational mode heaters maintain components above minimum operating temperature limit so that they won’t require warm-up time to do science.

  17. Heater Power Predictions *Operational mode heaters maintain components above minimum operating temperature limit so that they won’t require warm-up time to do science.

  18. Heater Power Predictions for Louver Option #1

  19. Heater Power Predictions for Louver Option #2

  20. Radiator Sizes for Louver Option #1

  21. Radiator Sizes for Louver Option #2

  22. Mass Estimates/TRL

  23. Mass Estimates/TRL for Louver Option #1

  24. Mass Estimates/TRL for Louver Option #2

  25. Conclusions and Recommendations • Thermal design meets temperature requirements and have sufficient margin • Radiator locations and CCHP routing allow CCHP operate in reflux mode to overcome gravity issue in ground testing • If spacecraft could provide 355 W survival heater power, louvers are not needed • Thermal louver Options #1 (~$200K) and #2 (~$100K) reduce survival heater power to 149 W and 246 W, respectively, if needed • Mechanical support structure is needed for radiators • ADR CE and FEE require temperature stability and should be away from other electronics, and located close to their own radiator to minimize CCHP length • Kevlar of MLI enclosure provides micrometeoroid protection for electronics boxes, CCHPs, harness, etc.

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