Thermal Design Matthieu GASQUET Cranfield University / Rutherford Appleton Laboratory Coseners House July 9th 2002 EUS consortium meeting
Feb 01, 2016
Thermal Design
Matthieu GASQUET
Cranfield University / Rutherford Appleton Laboratory
Coseners HouseJuly 9th 2002EUS consortium meeting
TopicsEUS Thermal environment & requirements
Steady State thermal analysis
Transient thermal analysisParameters Results
Conclusion
Thermal Environment(1/2)During the nominal phase (0.2 to 0.8 A.U.), heat load varies from 2200W/m2 to 34000W/m2
Graph1
33569.59094
32291.94278
30392.45598
28124.9802
25722.45326
23358.16422
21139.52701
19120.16377
17316.95835
15724.94619
14327.92072
13105.1012
12034.9331
11097.04225
10273.09432
9547.04797
8905.097225
8335.471605
7828.186102
7374.788154
6968.123634
6602.130458
6271.661639
5972.335766
5700.412054
5452.686389
5226.405191
5019.194028
4828.998405
4654.034693
4492.749255
4343.784423
4205.950065
4078.199695
3959.610471
3849.366265
3746.743359
3651.098334
3561.857713
3478.509154
3400.59391
3327.700325
3259.458259
3195.534259
3135.627406
3079.465632
3026.802635
2977.41509
2931.100228
2887.673749
2846.967979
2808.830212
2773.121282
2739.714314
2708.493582
2679.353522
2652.197863
2626.938817
2603.49642
2581.797904
2561.777137
2543.374149
2526.534712
2511.20993
2497.355922
2484.933532
2473.908033
2464.248944
2455.929788
2448.927957
2443.22455
2438.804266
2435.65529
2433.769243
2433.141116
2433.769243
2435.65529
2438.804266
2443.22455
2448.927957
2455.929788
2464.248944
2473.908033
2484.933532
2497.355922
2511.20993
2526.534712
2543.374149
2561.777137
2581.797904
2603.49642
2626.938817
2652.197863
2679.353527
2708.493582
2739.714314
2773.121282
2808.830212
2846.967979
2887.673749
2931.100222
2977.41509
3026.802635
3079.465634
3135.627404
3195.534265
3259.458259
3327.700328
3400.59391
3478.509158
3561.857713
3651.09833
3746.743359
3849.366261
3959.610465
4078.199689
4205.950065
4343.784429
4492.74925
4654.034693
4828.998405
5019.194028
5226.405191
5452.686389
5700.412054
5972.335777
6271.661646
6602.130458
6968.123634
7374.788165
7828.186113
8335.471605
8905.097238
9547.04797
10273.09431
11097.04225
12034.9331
13105.10121
14327.92075
15724.94619
17316.9583
19120.16377
21139.52701
23358.16422
25722.45326
28124.98023
30392.45598
32291.94272
33569.59094
34021.72998
Heat Load Vs Days
Days from Perihelion
Heat load (W/m2)
heat_load_time_function
DAY 133569.59094
32291.94278
30392.45598
28124.9802
DAY 525722.45326
23358.16422
21139.52701
19120.16377
17316.95835
DAY 1015724.94619
14327.92072
13105.1012
12034.9331
11097.04225
DAY 1510273.09432
9547.04797
8905.097225
8335.471605
7828.186102
DAY 207374.788154
6968.123634
6602.130458
6271.661639
5972.335766
DAY 255700.412054
5452.686389
5226.405191
5019.194028
4828.998405
DAY 304654.034693
4492.749255
4343.784423
4205.950065
4078.199695
DAY 353959.610471
3849.366265
3746.743359
3651.098334
3561.857713
DAY 403478.509154
3400.59391
3327.700325
3259.458259
3195.534259
DAY 453135.627406
3079.465632
3026.802635
2977.41509
2931.100228
DAY 502887.673749
2846.967979
2808.830212
2773.121282
2739.714314
DAY 552708.493582
2679.353522
2652.197863
2626.938817
2603.49642
DAY 602581.797904
2561.777137
2543.374149
2526.534712
2511.20993
DAY 652497.355922
2484.933532
2473.908033
2464.248944
2455.929788
DAY 702448.927957
2443.22455
2438.804266
2435.65529
2433.769243
DAY 752433.141116
2433.769243
2435.65529
2438.804266
2443.22455
DAY 802448.927957
2455.929788
2464.248944
2473.908033
2484.933532
DAY 852497.355922
2511.20993
2526.534712
2543.374149
2561.777137
DAY 902581.797904
2603.49642
2626.938817
2652.197863
2679.353527
DAY 952708.493582
2739.714314
2773.121282
2808.830212
2846.967979
DAY 1002887.673749
2931.100222
2977.41509
3026.802635
3079.465634
DAY 1053135.627404
3195.534265
3259.458259
3327.700328
3400.59391
DAY 1103478.509158
3561.857713
3651.09833
3746.743359
3849.366261
DAY 1153959.610465
4078.199689
4205.950065
4343.784429
4492.74925
DAY 1204654.034693
4828.998405
5019.194028
5226.405191
5452.686389
DAY 1255700.412054
5972.335777
6271.661646
6602.130458
6968.123634
DAY 1307374.788165
7828.186113
8335.471605
8905.097238
9547.04797
DAY 13510273.09431
11097.04225
12034.9331
13105.10121
14327.92075
DAY 14015724.94619
17316.9583
19120.16377
21139.52701
23358.16422
DAY 14525722.45326
28124.98023
30392.45598
32291.94272
33569.59094
DAY 15034021.72998
heat_load_time_function
Heat Load Vs Days
Days from Perihelion
Heat load (W/m2)
EUS thermal requirements (1/2)The Radiator Area is limited by the footprint of the EUS casing (1.4m x 0.4m = 0.56m2)
Coatings, and in particular multilayer coatings applied on mirrors have to be maintained in a reasonable range of temperature ( below 100C )
The EUS should be cooled as much as possible with a passive control system because of the limited mass and power budget ( also more reliable):Radiators, Multi Layer Insulation, Thermal control coatings,
EUS thermal requirements (2/2)A small part of energy has to reach the detector ( few Watts)Materials used for mirror and structure have to be thermally stable:
Steady State analysis (1/3)Assumptions:
Based on the worst hot case: 34000 W/m2Radiator temperature fixed to 50 CMirrors and Heat Stop temperature fixed to 61 CNo view factors between the heat shield and the radiators
Steady State analysisGrazing incidence telescope
M1 absorptivity0,10M2 absorptivity0,70rastering mirror absorptivity0,25total heat absorption on M1 (W)10,23total heat absorption on M2 (W)61,24total heat absorption on rastering mirror (W)0,66heat load coming from the rastering mirror to the slit 1,97Minimum Total radiator area (m2)0,125
Telescope design(2/2)Off-axis design
The off-axis design is the most challenging one from a thermal point of view
M1 absorptivity0,10heat stop absorptivity0,70heat stop transmissivity0,05M2 absorptivity0,83total heat absorption on M1 (W)26,30total heat absorption on heat stop (W)165,69total heat absorption on M2 (W)9,82heat load coming from M2 to the slit 2,01Minimum Total radiator area (m2)0,349
Transient simulationBased on the Off-axis telescope designMade with ESARAD/ESATAN and I-DEASThe simulation is based on the nominal phase orbit ( 0.2 to 0.8 A.U)The heat load is applied to the heat shield and the primary mirrorThere is no physical contact between the heat shield and the rest of the spacecraft
The geometric model (1/2)Different parts have been modeled:The heat shield The telescope casingThe mirrors and the heat stopThe radiators for the primary mirror and the heat stop
The geometric model (2/2)The area of the radiator has been fixed to the results given by the worst hot case steady state calculation:0.39 m2 for the M1 radiator area0.01 m2 for the heat stop radiator area
Model descriptionDifferent coatings are applied on each face of the parts to control the temperature
Thermal strategies
Three parameters have been studied in this simulation:
the emissivity of the telescope casing and heat shield
The absolute conductance between M1 and its radiator
The absorptivity of M1
Results (1/4)M1 temperature without radiator:
Results (2/4)M1 temperature with a conductance of 0.5 W/C between the radiator and M1, a high emissive coating and M1 either lowly or highly absorptive:
Results (3/4)M1 temperature with a low emissive coating on the heat shield, M1 lowly absorptive, and a conductance of 50 W/C.
Results (4/4)M1 temperature with a high emissive coating (MLI) on the telescope, M1 either lowly or highly absorptive, and a conductance of 50 W/C
Comments With a good absolute conductance and a large radiator, it seems that the thermo-optical properties of M1 dont have a big impact on its temperature.With a high emissive coating on the telescope casing and heat shield, the maximum temperature limit is in the requirements, but it is oscillating a lot.
Comments necessary to put heat switches or Variable conductance heat pipe to control the temperature with a better accuracy
Temperature (C)Absolute Conductance (W/K)-2000.01-200.0100.5101.0150100
Graph2
0.01
0.01
0.5
1
100
Conductance VS Temperature
Conductance VS Temperature
Feuil1
-2000.01
-200.01
00.5
101
150100
Feuil1
Conductance VS Temperature
Feuil2
Feuil3
Future workHeat shield thermal analysis and designDetailed analysis of the temperature mapping on M1Variable conductance heat pipe implementationParametric study of the model with Radiator area
conclusionImportance of heat shield thermal properties and mechanical mounting.The off-axis design seems feasible from a thermal point of view provided that:the heat shieldis conductively isolatedthe required thermo-optical properties (alpha and epsilon) are achieved on the heat shield at the elevated temperaturesthe required radiator area is accommodated the necessary thermal links are provided between the M1 mirror and its radiator