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ROCSAT-2 Thermal Design Description ISUAL(AP, SP, CCD and AEP) is thermally isolated from the payload platform to reduce the platform’s thermal distortion. The locations of the AEP and IRU had changed in the CDR phase. ISUAL has the independent thermal control to keep the temperatures within their limits. Thermostat controlled heaters are used on ISUAL units to keep the temperatures within their limits in ASH mode. Thermal control devices such as the radiator, MLI and heater are used to maintain the temperatures within their operating/non- operating limits.
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ROCSAT-2
Critical Design ReviewISUAL Thermal Interface Design / Analysis Report
Jeng-Der (J.D.) Huang (黃正德 )Tsung-Yao (Andy) Chen (陳宗耀 )
Jih-Run (J.R.) Tsai (蔡志然 )
ROCSAT-2
Contents
• Thermal Design Description
• Thermal Analysis Assumptions
• Configuration
• Power Dissipation
• Thermal Analysis Results
• Results Discussion
• Thermal Hardware Description
• Issues and Concerns
ROCSAT-2Thermal Design Description
• ISUAL(AP, SP, CCD and AEP) is thermally isolated from the payload platform to reduce the platform’s thermal distortion.
• The locations of the AEP and IRU had changed in the CDR phase.
• ISUAL has the independent thermal control to keep the temperatures within their limits.
• Thermostat controlled heaters are used on ISUAL units to keep the temperatures within their limits in ASH mode.
• Thermal control devices such as the radiator, MLI and heater are used to maintain the temperatures within their operating/non-operating limits.
ROCSAT-2
The internal heat dissipations of ISUAL units used orbit-averaged values. The predicted interface temperatures are unit radiator temperatures for
worst hot and cold cases. The units are thermally isolated from the payload platform with interface
conductance value of 0.064 W/°C. The heat of each unit part is conducted through the screws with
conductance values of 0.76 W/°C for M4 type screw and 0.6 W/°C for M3 type.
The conductance between the lens and lens/CCD assembly of CCD Imager is 0.02 W/°C.
The Spectrophotometer filter is insulated from the ring with conductance value of 0.002 W/°C.
Thermal Analysis Assumptions
ROCSAT-2Configuration
STR
Array Photometer
Spectrophotometer
CCD ImagerAEP
RSI
IRU
ROCSAT-2Configuration (Continued)
AEP
IRU
RSI
Spectrophotometer
Array Photometer
CCD Imager
STR
ROCSAT-2
• Nominal hot (operating)
Power Dissipation
Power Dissipation (W) Phase Number 1 2 3 4 5 6 7 8 9 10 11 12 13 Mean
CCD Imager 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9
Spectrophotometer 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4
Array Photometer 11.9 11.9 11.9 4.8 4.8 4.8 4.8 4.8 4.8 4.8 11.9 11.9 11.9 7.7
AEP 25.4 25.4 25.4 22.6 22.6 22.6 22.6 22.6 22.6 22.6 25.4 25.4 25.4 23.7
ROCSAT-2
• Nominal cold (stand-by)
Power Dissipation (Continued)
Power Dissipation (W) Phase Number 1 2 3 4 5 6 7 8 9 10 11 12 13 Mean
CCD Imager 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9 7.9
Spectrophotometer 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4 2.4
Array Photometer 4.8 4.8 4.8 4.8 4.8 4.8 4.8 4.8 4.8 4.8 4.8 4.8 4.8 4.8
AEP 22.6 22.6 22.6 22.6 22.6 22.6 22.6 22.6 22.6 22.6 22.6 22.6 22.6 22.6
ROCSAT-2
• ASH mode
Power Dissipation (Continued)
Power Dissipations (W)Phase Number 1 2 3 4 5 6 7 8 9 10 11 12 13 Mean
CCD Imager 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Spectrophotometer 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Array Photometer 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
AEP 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
ROCSAT-2
• Radiator area requirement
Thermal Analysis Results
Area(cm2)
CCD Imager 265.0 Spectrophotometer 18.6 Array Photometer 152.0
AEP 934.0
ROCSAT-2
Thermal Analysis Results- Radiator and Heater Locations
Radiator(Heater with 4 thermostats imbedded)
Array Photometer
Radiator(Heater with 4 thermostats imbedded)
CCD Imager
AEP
RadiatorRadiator(Heater with 4 thermostats imbedded)
Spectrophotometer
ROCSAT-2
Thermal Analysis Results (Continued)
(129, -417, 744)
(129, -417, 540)
(129, -487, 407)
(129, -741, 539)
(129, -741, 679)
(129, -651, 769)
(129, -521, 853)
Z
Y
• AEP Radiator Coordinates (Provided by Astrium)
Unit: mm
ROCSAT-2
• Orbit averaged heater power requirement
Thermal Analysis Results (Continued)
Set-point (C) Nominal Hot(W)
Nominal Cold(W)
ASH Mode (W) Nominal
mode ASH
mode
CCD Imager - - 1.8 - -25.0/-20.0*
Spectrophotometer - - 0.4 - -25.0/-20.0* Array Photometer - - 2.7 - -25.0/-20.0*
AEP - - - - -
*Set-point of Thermostat: -25 3 C / -20 3 C, dead-band 4 C
ROCSAT-2
• Predicted interface temperatures for nominal hot case
Temperature (oC) Predicted Operating Non-Operating Margin
Min. Max. Min. Max. Min. Max. Min. Max.
CCD Imager 15.5 16.3 -20.0 30.0 - - 35.5 13.7 Spectrophotometer 10.2 10.8 -20.0 30.0 - - 30.2 19.8 Array Photometer 12.3 13.3 -20.0 30.0 - - 32.3 16.7
AEP 34.4 41.4 -40.0 50.0 - - 74.4 8.6
Thermal Analysis Results (Continued)
ROCSAT-2
• Predicted interface temperatures for nominal cold case (stand-by mode)
Temperature (oC) Predicted Operating Non-Operating Margin
Min. Max. Min. Max. Min. Max. Min. Max.
CCD Imager 9.3 10.0 -20.0 30.0 - - 29.3 20.0 Spectrophotometer 1.1 1.8 -20.0 30.0 - - 21.1 28.2 Array Photometer 5.5 6.9 -20.0 30.0 - - 25.5 23.1
AEP 17.4 20.7 -40.0 50.0 - - 57.4 29.3
Thermal Analysis Results (Continued)
ROCSAT-2
• Predicted interface temperatures for ASH case
Thermal Analysis Results (Continued)
Minimum temperature (oC) Predicted Operating Non-operating Margin
Min. Max. Min. Max. Min. Max. Min. Max.
CCD Imager -25.0 -20.0 - - -35.0 40.0 10.0 60.0 Spectrophotometer -25.0 -20.0 - - -35.0 40.0 10.0 60.0 Array Photometer -25.0 -20.0 - - -35.0 40.0 10.0 60.0
AEP -37.6 -33.0 - - -55.0 55.0 17.4 88.0
ISUAL instruments are thermally controlled by thermostats in ASH mode.
ROCSAT-2
• CCD Imager, Spectrophotometer and Array Photometer survival heaters are controlled by thermostats instead of thermistors, and the dead-bands (the difference between lower and upper temperature set-points) for the thermostats are all 5C.
• The top extended surface of the AEP is used as the radiator, and ISUAL total radiator areas are 0.143 m2.
• Both worst hot and cold predicted temperatures of ISUAL are within the maximum and minimum operating/non-operating limits with proper margins by applying radiators and heaters.
• CCD Imager and Spectrophotometer have more detailed internal thermal models and these can improve the accuracy of interface temperature predictions.
Results Discussion
ROCSAT-2Thermal Hardware Description
• The thermal filler “Cho-Them” should be applied between the AEP box and radiator to increase the interface thermal conductance.
• Silver-Teflon SSM (Second Surface Mirror) radiator is applied on unit surfaces to radiate unit waste heat to the space.
• The ISUAL MLI design has been completed, and the MLI drawings for AEP, CCD Imager, Spectrophotometer and Array Photometer were made by NSPO. These drawings should be reviewed by UCB and then Astrium.
ROCSAT-2CCD Imager MLI Drawing
ROCSAT-2
CCD Imager MLI Drawing(Continued)
ROCSAT-2Spectrophotometer MLI Drawing
ROCSAT-2Array Photometer MLI Drawing
ROCSAT-2AEP MLI Drawing
ROCSAT-2
• Current analysis results are based on very limited unit thermal information. The more detailed analysis must be performed after the following information are given by UCB.
More detailed mass break down for each unit Clear power profile for each unit in nominal, stand-by, and survival modes Heat transfer paths inside the units, especially in some critical parts such as lens, filters, etc. Lens (instrument-controlled) heater operations (i.e., on/off, temperature set point, etc.) CCD thermoelectric cooler thermal capability
• NSPO is only responsible for ISUAL unit thermal interface control based on the unit internal thermal information given by UCB, and UCB should be responsible for ISUAL unit internal design and thermal performance.
Issues and Concerns
