1. GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Section 4.4 Heat Pipe Design and Analysis1 GLAST Large Area Telescope: Mechanical Systems Peer Review 27 March 2003 Section 4.4 Heat Pipe Thermal Design Aaron Avallon Heat Pipe Product Center Design Engineer aaron.r.avallon@lmco.com Gamma-ray Large Area Space Telescope

2. GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Section 4.4 Heat Pipe Design and Analysis2 Heat Pipe Performance Requirements Based on:Results of Overall LAT Thermal Math Model Verification Methods A: Analysis T: Test Margin is determined by: EP/Req Must be > 1.3

3. GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Section 4.4 Heat Pipe Design and Analysis3 Heat Pipe Sizing (1 of 2) All worst case pipe requirements derived from detailed thermal model hot case with the following assumptions and results –Top Flange 1 of 5 pipes failed Cumulative heat load and transport requirement calculated directly from Heat Flux (W/m) vs Length Along Pipe (mm) graph Results in a 9.2 W-m requirement for each pipe –Downspout 1 of 6 pipes failed Maximum environmental load on one radiator panel Maximum dissipation from the grid of 252 W All grid heat load must be transported to one radiator Resulting power requirement for each pipe is 40 W

4. GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Section 4.4 Heat Pipe Design and Analysis4 Heat Pipe Sizing (2 of 2) –X-LAT 1 of 6 pipes failed Cumulative heat load and transport requirement calculated directly from Heat Flux (W/m) vs Length Along Pipe (mm) graph Results in a 59.5 W-m requirement for each pipe –VCHP 1 of 6 pipes failed Maximum environmental load on one radiator panel Maximum dissipation from the LAT of 612 W to be dissipated into one radiator panel Resulting power requirement for each pipe is 94 W

5. GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Section 4.4 Heat Pipe Design and Analysis5 Heat Pipe Qual/Acceptance Tests (1 of 2) Qualification Tests –Extrusion charge optimization (VCHP only, new extrusion) –Burst: 4 * MEOP (Maximum Expected Operating Pressure) Constant Conductance Heat Pipe Acceptance Tests –Leak: Ammonia leak < 1x10 -7 scc/sec –Proof Pressure: Greater of 1.1 * MPP (Maximum Processing Pressure) or 1.5 * MEOP –Non-Condensable Gas: Verify acceptable level –Transport: Capability > 1.3 times requirement –Ammonia Charge: Mass recorded before and after charging

6. GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Section 4.4 Heat Pipe Design and Analysis6 Heat Pipe Qual/Acceptance Tests (2 of 2) Variable Conductance Heat Pipe Acceptance Tests –Leak: Ammonia leak < 1x10 -7 scc/sec –Proof Pressure: Greater of 1.1 * MPP (Maximum Processing Pressure) or 1.5 * MEOP –Transport: Capability > 1.3 times requirement –Control Gas (He/Ne) Charge Quantity: Verify correct quantity –Ammonia Charge: Mass recorded before and after charging –Wicking: Tested to insure sufficient wicking (In process test) –Control Performance: Deferred to radiator assy level

7. GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Section 4.4 Heat Pipe Design and Analysis7 Heat Pipe Structural Analysis (1 of 2) Top Flange and Downspout Heat Pipes external loads insignificant relative to internal loads due to mounting configuration – Structural integrity demonstrated by heat pipe Qual./Acceptance tests X-LAT Heat Pipe covered in X-LAT Plate structural analysis presentation VC Heat Pipe covered in Radiator Assembly structural analysis presentation, preliminary analysis covering reservoir and transition complete with the following assumptions and results: –MEOP of 377 PSI (140ºF)**(requirements changed to 490 PSI) –MPP of 882 PSI (210 ºF) –Acceleration loads of 35 G’s replace external flight loads

8. GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Section 4.4 Heat Pipe Design and Analysis8 Heat Pipe Structural Analysis (2 of 2) LocationLoading Condition YieldUltimate FOSM.S.FOSM.S. Reservoir – Inertia WeldMEOP1.53.54.01.0 Reservoir – Inertia WeldMPP1.11.61.251.7 Transition Tube – Orbital WeldMEOP1.56.74.06.2 Transition Tube – Orbital WeldMPP1.13.81.259.5 Transition Tube – Inertia WeldMEOP1.57.04.06.5 Transition Tube – Inertia WeldMPP1.13.71.259.3 Transition Tube – Inertia WeldMEOP + Acceleration 1.63.62.08.2 MEOP: Maximum Expected Operating Pressure MPP: Maximum Processing Pressure

9. GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Section 4.4 Heat Pipe Design and Analysis9 VCHP Reservoir & Radiator Sizing Reservoir Sizing: –Hot case effective sink temperature = 233 K –Cold case effective sink temperature = 193 K –Computed storage volume ratio = 1.1 (-10ºC to +15ºC) –Required reservoir volume = 75 cc

10. GLAST LAT ProjectDOE/NASA Mechanical Systems Peer Review, March 27, 2003 Section 4.4 Heat Pipe Design and Analysis10 Document Status Document TitleDocument #% CompleteRelease Status Top Flange Assy2A1570395In Review Downspout Assy2A1570595In Review X-LAT Assy2A1570495In Review VCHP Assy2A1570695In Review Reservoir Assy2A1572295In Review Wick Assy2A1572395In Review Top Flange Spec2A1569995In Review Downspout Spec2A1570195In Review X-LAT Spec2A1570095In Review VCHP Spec2A1570225Draft Top Flange ATP2A1570760Draft Downspout ATP2A1570960Draft X-LAT ATP2A1570860Draft VCHP ATP2A1571050Draft