LAT Ground Cooling. The function of the LAT Ground Cooling System is twofold: 1. To provide cooling in lieu of radiators for all ground operations.

Size: px

Start display at page:

Download "LAT Ground Cooling. The function of the LAT Ground Cooling System is twofold: 1. To provide cooling in lieu of radiators for all ground operations."

Luke McBride
5 years ago
Views:

1 The function of the LAT Ground Cooling System is twofold: 1. To provide cooling in lieu of radiators for all ground operations. 2. To provide additional cooling/heating capacity during LAT thermal vacuum testing to reduce cycle times. 3. Test requirements are defined in: LAT Test Thermal Requirements LAT-TD (5/21/03) Document needs to be updated.

2 LAT Test Thermal Requirements LAT-TD (5/21/03) Test Location / Config. Purpose Thermal Req. Cooling Method Dur. Cal Unit Beam Test SLAC End Station A/ sideways / 1x4 array with CU ACD LAT science calibration CU Control Temperature stable at 17+/-1 C (TBR) Glycol-cooled chill plates mounted to Grid/ natural convection for E-Boxes 60 days In-Air Muon Survey SLAC Bldg 33/NRL LAT +Z sideways and upright No radiators Cosmic-ray muon survey of TKR positions LAT Control Temperature stable at 17+/-1 C (TBR) Glycol-cooled chill plates mounted to Grid / forced air on E-Boxes 5 days Airborne Cosmic Ray Test* Airplane / upright in shipping container Integrated sensor, electronics, software system test in orbital particle env. TKR max temp < 30 C; No stability req Glycol-cooled chill plates mounted to Grid / forced air on E-Boxes 3 hr -when LAT is on at cruising altitude EMI/EMC Compatibility Test EMI Chamber at NRL; LAT upright; No radiators Verify LAT EMI requirements TKR max temp < 30 C; No stability req Glycol-cooled chill plates mounted to Grid / forced air on E-Boxes 8 hr (TBR) Thermal Balance Test NRL T-Vac Chamber LAT +Z sideways Radiators integrated Thermal model validation over operating range LCT between -10 C and 17 C (TBR) Radiative cooling to cold walls ~14 days T-Vac w/ Muon Survey NRL T-Vac Chamber / +Z sideways LAT perf verif over operating range Geant 4, FEA model validation LCT at (TBR): 10 C +/-1 C 0 C +/-1 C 17 C +/-1 C Radiative cooling to cold walls GN 2 chill plates mounted to Grid 20 days Aliveness Test Various locations Electronics aliveness No stability req / ambient temp deg C (TBR) No cooling (TBR) / LAT thermal capacitance absorbs heat load < 30-min LPT Vibe table, shipping container, T-Vac stand, observatory, acoustic chamber Functional test TKR max temp < 30 C No stability req Forced air in E-box volume 2-hr CPT SLAC Bldg 33/NRL LAT upright No radiators Full functional test and sensor calibration TKR max temp < 30 C No stability req Glycol-cooled chill plates on Grid Forced air on E-Boxes 5 days

3 The LAT Ground Cooling will be used at all times when the LAT instrument must be functional for more than about 2 hours (E-boxes approach AT limit).

4 The LAT Ground Cooling System will be used when only the electronics boxes are operational for more than 4 hours (E-boxes approach AT limit).

5 During LAT level thermal vacuum cycling, additional GRID cooling/heating capacity can significantly decrease cycle times (simplified one node model). LAT Transients Temperature Change rate Half Cycle Time Temperature Change Rate, K/hr Half-Cycle Time, hr Thermal Mass = 939,000 J/K Q (radiators) = 1200 W HEX Capacity, W

6 During LAT level thermal vacuum cycling, additional GRID cooling/heating capacity can significantly decrease cycle times (simplified one node model). Trasient Cooldown - One Lumped Node Qconv = 0 Qconv = 1000 W Qconv = 2000 W mcp = 939,000 J/K Qrad = 1200 W Temperature, C Time, hours

7 X-LAT Plate Heat Exchanger Heat Pipes (6) Ground cooling tube

8 GRID Heat Exchanger Attachment point of GRID Heat Exchangers (2)

9 Heat Transfer Media 3M Fluorinert Electronic Liquids have been used as heat transfer media for numerous applications including direct contact cooling, automated testing, etching and CVD. Characteristcs of these liquids are: High dielectric strength Thermal and chemical stability Wide range of boiling points Good materials compatibility Non-flammable Low toxicity (practically non-toxic) Zero Ozone Depletion Potential (ODP) High global warming potential (GWP) [Must minimize emissions] Long atmospheric lifetime [Must minimize emissions]

10 Heat Transfer Media Water

11 Heat Transfer Media

Test Readiness Review

GLAST Large Area Telescope Gamma-ray Large Area Space Telescope LAT Thermal Vacuum Test Test Readiness Review Jesse Armiger Thermal Vacuum Test Director Naval Research Laboratory Thermal Vacuum Test 1