Thermal Control Design

J.D. Huang (黃正德 )Mechanical Engineering SectionNational Space Program Office

April 14, 2005

Contents

• Key Requirements• Thermal Information• Geometric Mathematical Model• Assumptions• Thermal Analysis Cases• Thermal Analysis Results • Conclusions

Key TCS Requirements

• Passive thermal control– The thermal control should be achieved through passive elements, as

thermal blankets, insulation, and surface finishes.– Materials should be selected for low-outgassing characteristics.

• Thermal margin– For components that have no thermal control or have passive control

only, an uncertainty margin of 5.

• Heaters– If thermostats are used, the thermostat shall be redundant.– Each heater shall be provided with a ground-commandable override

capability.– Each heater shall be sized to control to 5 deg C above its minimum

allowable temperature or to control the component at its minimum allowable temperature with 25% excess control authority.

Thermal Information - Attitude

• Altitude : 400 ~ 800 km• Beta angle : -90 ~+90 deg• Attitude : Normal mode, Safehold mode,

Orbit Control mode

Thermal Information- Temperature Limits

Payload Operating (°C) Non-operating (°C)GPS Occ. Rx : -20 to +60 -30 to +70GPS Occ. Ant. -125 to +105 -125 to +105TBB -10 to +50 -20 to +70TBB Ant. -125 to +105 -125 to +105TIP -10 to +50 -10 to +50SSR/PC -10 to +40 -25 to +40

BUSPower

Battery -5 to +30 -5 to +30BCR+PDU -25 to +50 -35 to +60Solar Array -100 to +105 -100 to +105

C&DHSBFC -20 to +65 -45 to +70IIU -20 to +65 -45 to +70Mass Memory -20 to +65 -45 to +70

ADCS Operating (°C) Non-operating (°C)Torque Rods -30 to +40 -50 to +61Reaction Wheel -10 to +50 -35 to +61Sun Sensor -95 to +80 -105 to +90Earth Sensors -40 to +40 -40 to +61IRU (3-axis) -25 to +55 -25 to +55Magnetometer -60 to +50 -60 to +50GPS Rx. -10 to +40 -25 to +40GPS Ant. -55 to +71 -55 to +71

TT&C Hybrid -10 to +40 -25 to +40

Diplexer -10 to +40 -25 to +40Transceiver -10 to +40 -25 to +40

Thermal information-Temperature Limits (Continued)

Propulsion Operating (°C) Non-operating (°C)Latching Valve +7 to +55 +7 to +55Press. Transducer +7 to +55 +7 to +55Thruster +7 to +55 +7 to +55Tank +7 to +55 +7 to +55Filter +7 to +55 +7 to +55Fill Drain Valve +7 to +55 +7 to +55

Thermal information-Temperature Limits (Continued)

Thermal Information- Power Dissipation

Power Dissipation (W) Component Normal Mode Safehold Mode Orbit Control Mode

Payload Daytime Eclipse Daytime Eclipse Daytime Eclipse GPS Occ. Rx. 16 16 0 0 0 0

TBB 4 4 0 0 0 0 TIP 5 5 0 0 0 0

SSR/PC 10 10 0 0 0 0 GPS OCC. Ant. 0 0 0 0 0 0

TBB Ant. 0 0 0 0 0 0

Power Dissipation (W) Component Normal Mode Safehold Mode Orbit Control Mode

Bus Daytime Eclipse Daytime Eclipse Daytime Eclipse Power - Battery 0 17 0 17 0 17

BCR+PDU 2 2 2 2 2 2 C&DH- SBFC 8 8 8 8 8 8

IIU 6 6 6 6 6 6 Mass Memory 4 4 4 4 4 4

TT&C- Hybrid 0 0 0 0 0 0 Diplexer 0 0 0 0 0 0

Transciver 13 13 13 13 13 13 ADCS- Torque Rods 0.06 0.06 0.075 0.075 0 0

Reaction Wheel 2 2 2 2 2 2 Sun Sensor 0.1 0.1 0.1 0.1 0.1 0.1

Earth Sensor 0.35 0.35 0 0 0.35 0.35 IRU (3-axis) 0.8 0.8 0 0 0.8 0.8

Magnetometer 0.2 0.2 0.2 0.2 0.2 0.2 GPS Rx. 5 5 0 0 5 5

Propulsion- Tank 0 0 0 0 0 0 Latching Valve 1.2 1.2 1.2 1.2 1.2 1.2

Press. Transducer 0 0 0 0 0 0 Thruster 0 0 0 0 0 0

Filter 0 0 0 0 0 0 Fill Drain Valve 0 0 0 0 0 0

Thermal Information- Power Dissipation (Continued)

Geometric Mathematical Model

• Internal model

Battery

GPS Occ.

Tank

C&DH

TIP

PDU

RWS-B

and

L-B

and

z

x

y

Torq

ue R

od

yx

z

SSR/PCTBB

ADCS GPS RX

BCR

LACHVALVE

MLI

Radiator

Geometric Mathematical Model (Continued)

• External model • Orientation (Normal Mode)

• Orientation (Safe-hold Mode)

Eclipse

Sun

SunOrientation

RotationRate=2 rev./orbit

Earth

Eclipse

Sun

EarthOrientation

Earth

Assumptions

• +Y and –Y side solar panels will be deployed to 90 deg from the stowed condition and decoupled from the spacecraft bus.

• Thermal capacitance of each component is assumed to be 900 (J/kg°C) x mass (kg).

• Contact conductance of battery is assumed to be 200 (W/m2°C) and Others are 30 (W/m2°C).

• RCS tank is isolated ( 0.01 W/°C ) from deck and covered with MLI to reduce the internal radiation coupling with other components.

• Heat conductions between deck and the side panels are through eighteen(18) M4 screws with the value of conductance of 0.76 (W/m2°C).

Thermal Analysis Cases

Altitude(km)

Beta Angle (deg)

Thermo-optical

Properties

Thermal Envir.

Thermal Design

Normal Operating

Mode

400 0, ±45, ±90

EOL Hot Radiator sizing

BOL Cold Heater power check

600 0, ±45, ±90

EOL Hot Radiator sizing

BOL Cold Heater power check

800 0, ±45, ±90

EOL Hot Radiator sizing

BOL Cold Heater power check

Safe-hold Mode

400 0, ±45, ±61 ,±90

BOL Cold Heater power sizing

600 0, ±45, ±61 ,±90

BOL Cold Heater power sizing

800 0, ±45, ±61 ,±90

BOL Cold Heater power sizing

Thermal Analysis Results-Radiator & Required Heater Power

Radiator Area (m2)

0.42 Normal Operating,400 km, Hot CaseBeta Angle = 0o

Required Heater Power (W)

Environment Condition

Tank Battery

Normal Operating Mode

0.74 11.0 Normal Operating,800 km, Cold CaseBeta Angle = 90o

Safe-hold Mode 0.9 17.2 Safe-hold mode,800 km, Cold CaseBeta Angle = 61o

Thermal Analysis Results-Temperature Prediction

• The worst hot and cold temperatures for Normal Operating. Temperature (°C)

Predicted Operating Limit

Non-operatingLimit

Margin

Tmin. Tmax. Tmin. Tmax. Tmin. Tmax.

Tmin. Tmax.

GPS Occ. Rx 10.1 28.8 -20.0 +60.0 - - 30.1 31.2

TBB 7.3 26.2 -10.0 +50.0 - - 17.3 23.8

TIP 6.9 25.5 -10.0 +50.0 - - 16.9 24.5

Battery 1.0* 21.6 -5.0 +30.0 - - 6.0 8.4

Tank 7.0* 20.1 +2.0 +55.0 - - 5.0 34.9

C&DH 9.1 28.1 -20.0 +65.0 - - 29.1 36.9

PDU 3.3 22.0 -25.0 +50.0 - - 28.3 28.0

Receiver 12.9 31.3 -10.0 +40.0 - - 22.9 8.7

Reaction Wheel

5.9 24.5 -10.0 +50.0 - - 15.9 25.5

IRU 14.7 33.2 -25.0 +55.0 - - 39.7 21.8

Environment Condition

Normal Operating,800 km, Cold CaseBeta Angle = 90o

Normal Operating,400 km, Hot CaseBeta Angle = 0o

* Temperature controlled by heater

Thermal Analysis Results-Temperature Prediction (Cont’)

• The worst hot and cold temperatures for Safe-hold Mode.Temperature (°C)

Predicted OperatingLimit

Non-operatingLimit

Margin

Tmin. Tmax. Tmin. Tmax.

Tmin. Tmax.

Tmin. Tmax.

GPS Occ. Rx 0.7 1.4 - - -30.0 +70.0 30.7 68.6

TBB 0.3 1.9 - - -20.0 +70.0 20.3 68.7

TIP 0.7 1.8 - - -10.0 +50.0 10.7 48.8

Battery 1.0* 5.0 -5.0 +30.0 - - 6.0 25.0

Tank 7.0* 12.0 +2.0 +55.0 - - 5.0 43.0

C&DH 7.7 9.3 -20.0 +65.0 - - 27.7 56.2

PDU 2.7 3.8 -25.0 +50.0 - - 27.7 46.9

Receiver 11.8 13.2 -10.0 +40.0 - - 21.8 27.4

Reaction Wheel

4.7 5.8 -10.0 +50.0 - - 14.7 44.8

IRU 0.5 1.5 - - -25.0 +55.0 25.5 54.1

Environment Condition

Safe-hold Mode,800 km, Cold Case

Beta Angle = 61

Safe-hold Mode,400 km, Cold Case

Beta Angle = 61

* Temperature controlled by heater

Thermal Analysis Results-Temperature Plots

• Normal Hot, H=400 km, =0o • Normal Hot, H=800 km, =0o

0 10 20 30 40 50 60 70 80 90Time (min.)

10

15

20

25

30

35

40

Tem

pera

ture

(C

)

TankBatteryGPS Occ.SSR/PCTBBTIP

Daytime

Daytime

Eclipse

0 10 20 30 40 50 60 70 80 90 100Time (min.)

10

15

20

25

30

35

40

Tem

pera

ture

(C

)

TankBatteryGPS Occ.SSR/PCTBBTIP

Daytime

Daytime

Eclipse

Thermal Analysis Results-Temperature Plots (Continued)

(10 Orbits)

• Normal Hot, H=400 km, =90o • Normal Hot, H=800 km, =90o

0 100 200 300 400 500 600 700 800 900Time (min.)

-10

-5

0

5

10

15

20

Tem

pera

ture

(C

)

TankBattery

GPS Occ.SSR/PCTBBTIP

0 100 200 300 400 500 600 700 800 900 1000Time (min.)

-10

-5

0

5

10

15

20

Tem

pera

ture

(C

)

TankBattery

GPS Occ.SSR/PCTBBTIP

(10 Orbits) (10 Orbits)

Thermal Analysis Results-Temperature Plots (Continued)

• Normal Cold, H=800 km, =90o• Normal Cold, H=800 km, =0o

0 10 20 30 40 50 60 70 80 90 100Time (min.)

-10

-5

0

5

10

15

20

25

30

Tem

pera

ture

(C

)

TankBattery

GPS Occ.SSR/PCTBBTIP

0 100 200 300 400 500 600 700 800 900 1000Time (min.)

-10

-5

0

5

10

15

20

25

30

Tem

pera

ture

(C

)

Tank

Battery

GPS Occ.SSR/PC

TBB

TIP

(10 Orbits)

Thermal Analysis Results-Temperature Plots (Continued)

• Safe-hold Mode, H=800 km, =0o

0 100 200 300 400 500 600 700 800 900 1000Time (min.)

-10

-5

0

5

10

15

20

25

30

Tem

pera

ture

(C

)

Tank

Battery

GPS Occ.SSR/PC

TBB

TIP

• Safe-hold Mode, H=800 km, =61o

0 100 200 300 400 500 600 700 800 900 1000Time (min.)

-10

-5

0

5

10

15

20

25

30

Tem

pera

ture

(C

)

Tank

Battery

GPS Occ.SSR/PC

TBB

TIP

(10 Orbits) (10 Orbits)

Conclusions

• For both normal operating and safe-hold modes, all worst hot and cold predicted temperatures are within the operating/non-operating temperature ranges with proper margins.

• The total required radiator areas on the side panels are 0.42 m2.

• The total maximum required heater powers are 11.74 W for the normal operating mode and 18.1 W for safe-hold mode.

• The predicted radiator areas and heater powers can be reduced if less power consumption is required.

• All the thermal analysis results will be updated again if further design information is given.