FACILITY FOR HEAT TRANSFER MEASUREMENT FOR SATELLITE PROGRAMME

Transcription

1 FACILITY FOR HEAT TRANSFER MEASUREMENT FOR SATELLITE PROGRAMME P. P. GUPTA THERMAL SYSTEMS GROUP ISRO SATELLITE CENTRE BANGALORE

2 OUTLINE OF PRESENTATION RELEVANCE OF THE TOPIC TO SATELLITE PROGRAMME SELECTION OF TEST METHOD SPECIFICATIONS/ FEATURES OF FACILITIES MEASUREMENT TECHNIQUE EXPERIMENTAL RESULTS ACCURACY IN MEASUREMENTS OTHER TEST FACILITIES AT THERMAL SYSTEMS OF ISAC CONCLUDING REMARKS

3 POWER SYSTEMS TTC AOCE SUB-SYSTEMS OF SATELLITES GENERATION, CONDITIONING, DISTRIBUTION BATTERIES INERTIAL SYSTEMS PROPULSION SYSTEM ANTENNA STRUCTURES/ MECHANISMS THERMAL CONTROL SYSTEMS OPTICAL PAYLOADS TELESCOPE, CAMERA, DETECTORS COMMUNICATION PAYLOADS SSPAs, TWTAs, MUX/DEMUX, WAVE GUIDES, RECEIVERS, TRANSMITTERS ETC..

4 REASONS: RELIABLE EFFICIENT LONG LIFE TEMPERATURE CONTROL REQUIREMENTS OPERATIONAL/ FUNCTIONAL REQUIREMENTS DETECTOR TELESCOPE/ CAMERA CALIBRATION TARGETS TEMPERATURE CONTROL LIMITS DEPENDS ON NATURE OF THE SYSTEM MECHANICAL/ ELECTRONICS PASSIVE ANTENNA, WAVE GUIDES, STRUCTURAL ELEMENTS NATURE OF COMPONENTS USED - BATTERY TWTAs/ SSPAs/ HMCs/ ASICs PROPELLENTS

5 TYPICAL TEMPERATURE CONTROL REQUIREMENTS SUB SYSTEMS ELECTRONIC PACKAGES TTC/ POWER/ COMMUNICATION/ AOCE OPERATING TEMPERATURE RANGE IN 0 C -10 TO +50 REMARKS BATTERIES STAR SENSOR SENSORS PROPULSION SYSTEM ELEMENTS FUEL/ OX TANK ELECTROMECHANICAL SYSTEMS: WHEELS DTG SADA 0 TO +10, 0 TO +25, -10 TO TO TO TO TO TO TO TO +55 DEPENDS ON TYPE OF BATTERY SSPAs TWTA REMOTE SENSING CAMERA DETECTORS SHUNT MAGNETIC TORQUER ANTENNA -5 TO TO TO , -173, TO TO TO +95 GRADIENT <2 0 CONTROL ± 0.1 0

6 FACTORS AFFECTING THE TEMPERATURE DISTRIBUTION IN SPACECRAFT EXTERNAL LOADS SOLAR LOAD EARTH SHINE LOAD RADIATION FROM EARTH ALBEDO LOAD SOLAR RADIATION REFLECTED FROM EARTH THESE LOADS ON TO SPACECRAFT IS ALSO FUNCTION OF TYPE OF ORBIT, SHAPE OF SPACECRAFT & SPACECRAFT STABILISATION INTERNAL HEAT GENERATION ELECTRONIC DEVICES CHEMICAL REACTIONS R.F. LEAKAGES/ LOSSES MECHANICAL FRICTIONS NUCLEAR REACTIONS RADIATION EXCHANGE WITH IN THE SPACECRAFT CONDUCTION HEAT PATH WITH IN THE SPACECRAFT FOR ESTIMATING THE CONDUCTIVE COUPLING/ ISOLATION BETWEEN DIFFERENT NODES OF S/C WE NEED TO KNOW IN SPACE CONDITION THE THERMAL CONDUCTIVITY/ CONDUCTANCE OF THE MATERIALS USED IN THE SATELLITE.

7 MATERIALS USED IN SATELLITE METALLIC MATERIALS ALUMINIUM ALLOYS MAGNESIUM ALLOYS STAINLESS STEEL OFHC COPPER TITANIUM ALLOY BERYLLIUM COPPER COPPER BRAID INSULATING MATERIALS CFRP FRP G10 VESPEL TEFLON KEVLAR SILICA

8 MATERIALS USED IN SATELLITE COMPOSITES ALUMINIUM HONEYCOMB CORE WITH ALUMINIUM FACE SHEET ALUMINIUM HONEYCOMB CORE WITH CFRP FACE SHEET VARIOUS TYPES OF ADHESIVES THERMAL INTERFACE MATERIALS ECOTHERM TC8 CHOTHERM INDIUM FOIL SIL PAD SIGRAFLEX

9 MATERIALS USED IN SATELLITE LIST OF OTHER THERMAL MATERIALS FOR SATELLITE (WHOSE THERMAL CONDUCTIVITY IS NOT IMPORTANT) MLI MATERIAL ALUMINISED MYLAR ALUMINISED KAPTON POLYESTER NET SILICA WOOL BETA CLOTH THERMAL CONTROL COATINGS BLACK WHITE ALUMINIUM PAINT METALLISED FILMS/ SURFACES OPTICAL SOLAR REFLECTOR (OSR) ALUMINIUM COATINGS SILVERISED TEFLON GERMANIUM

10 THERMAL CONDUCTIVITY/ CONDUCTANCE THERMAL CONDUCTIVITY THE TIME RATE OF HEAT FLOW, UNDER STEADY STATE CONDITIONS, THROUGH A UNIT AREA PER UNIT TEMPERATURE GRADIENT IN THE DIRECTION PERPENDICULAR TO THE AREA. THERMAL CONDUCTANCE WHEN OTHER MODES OF HEAT TRANSFER THROUGH A MATERIAL ARE PRESENT IN ADDITION TO CONDUCTION, THE RESULTS OF THE MEASUREMENTS WILL REPRESENT THE APPARENT OR EFFECTIVE THERMAL CONDUCTIVITY OF THE TESTED MATERIAL OR ANOTHER TERM THERMAL CONDUCTANCE CAN BE USED. OR SIMPLY THERMAL CONDUCTANCE CAN BE DEFINED AS THE TIME RATE OF HEAT FLUX THROUGH A UNIT AREA OF A BODY INDUCED BY UNIT TEMPERATURE DIFFERENCE BETWEEN THE BODY SURFACES.

11 THERMAL CONDUCTIVITY MEASUREMENT TECHNIQUES STEADY STATE BASED ON THE HEAT FLUX ACROSS THE SAMPLE AND TEMPERATURE DIFFERENCE BETWEEN THE EDGES OF THE SAMPLE UNDER STEADY STATE CONDITION BY FOURIER S LAW. RADIAL HEAT FLOW AXIAL ROD COMPARATIVE GUARDED HEAT FLOW METER TRANSIENT METHOD BASED ON THE RATE OF RISE OF TEMPERATURE AGAINST TIME DUE TO THE THERMAL PERTURBANCE. LASER FLASH HOT WIRE HOT DISK

12 SELECTION OF TEST METHOD/ FACILITY MATERIALS TO BE TESTED METAL/ NON METAL/ COMPOSITES SIZE OF SAMPLES CONDUCTIVITY RANGE TEMPERATURE RANGE TEST ENVIRONMENT ACCURACY

13 SCHEMATIC OF A TYPICAL COMPOSITE PANEL STEADY STATE GUARDED HEAT FLOW METER METHOD IS SELECTED

14 GUARDED HEAT FLOW METER METHOD AS PER THE ASTM E 1530, GUARDED HEAT FLOW METER METHOD IS DEFINED AS: A SAMPLE OF THE MATERIAL TO BE TESTED IS HELD UNDER A REPRODUCIBLE COMPRESSIVE LOAD BETWEEN TWO POLISHED METAL SURFACES, EACH CONTROLLED AT A DIFFERENT TEMPERATURE. THE LOWER CONTACT SURFACE IS PART OF A CALIBRATED HEAT FLUX TRANSDUCER. AS HEAT FLOWS FROM THE UPPER SURFACE THROUGH THE SAMPLE TO THE LOWER SURFACE, AN AXIAL TEMPERATURE DIFFERENCE ACROSS THE SAMPLE ALONG WITH THE OUTPUT FROM THE HEAT FLUX TRANSDUCER, THERMAL CONDUCTIVITY OF THE SAMPLE CAN BE DETERMINED WHEN THE THICKNESS IS KNOWN.

15 FEATURES OF EQUIPMENT GUARDED HEAT FLOW METER TECHNIQUE MEASUREMENT AT CRYOGENIC & ELEVATED TEMPERATURES IN HIGH VACUUM OR IN INERT GAS OR IN ATMOSPHERIC ENVIRONMENTS VARIETY OF SAMPLE SIZES & SHAPES CONTACT PRESSURE ON THE SAMPLE NO SENSORS ON SAMPLE PC BASED AUTO CONTROLLED OPERATION & DATA ANALYSIS

16 SPECIFICATIONS OF THE THERMAL CONDUCTIVITY INSTRUMENT TYPE : STEADY STATE GUARDED HEAT FLOW METER METHOD THERMAL CONDUCTIVITY MEASUREMENT RANGE : 0.1 TO 30 W/mK TEMPERATURE RANGE : C TO C ENVIRONMENT : VACUUM > 10-5 TORR OR INERT GAS CONTACT PRESSURE : VARIABLE UP TO 25 Kg FORCE SAMPLE SIZE : 50, 70 & 100 mm SQUARE X 40 mm THICKNESS (MAX) 50 mm CIRCULAR X 40 mm THICKNESS (MAX) ACCURACY : ± 3 TO ± 8% REPEATABILITY : < ± 3% IN SITU THICKNESS MEASUREMENT GAUGE LN 2 COOLING FOR HEAT SINK WITH TEMPERATURE CONTROL FACILITY PC BASED AUTO CONTROL OPERATION & DATA ANALYSIS

17 VIEW OF THERMAL CONDUCTIVITY EQUIPMENT

18 INTERNAL VIEW : TEST ZONE DETAILS

19 SCHEMATIC BLOCK DIAGRAM OF THE FACILITY VACUUM GAUGES TURBO MOLECULAR PUMP MECHANICAL PUMP ELECTRONIC CONSOLE CONTROLS INTERFACES POWER SUPPLIES ELECTRICAL, PNEUMATIC AND LN 2 FEED - THROUGHS THICKNESS GAUGE MEASURING ASSEMBLY LN 2 CONTROLLED CRYOGENIC HEAT SINK OPERATING AND DATA ANALYSIS SOFTWARE CONTROL COMPUTER PERIPHERALS ACCESSORIES FOR USE INSIDE MEASURING ASSEMBLY LIQUID CELL PASTE CELL POWDER CELL PURGE GAS SUPPLY VACUUM ENCLOSURE LN 2 SUPPLY LN 2 CONTROLS

20 TEST ASSEMBLY WITH HFM

21 TEST SECTION SCHEMATIC HEAT SINK SPACER TOP HEATER UPPER PLATE Tu TEST SAMPLE Tm LOWER PLATE REFERENCE SAMPLE GUARD HEATER Tg HEAT FLUX METER T L BOTTOM HEATER SPACER HEAT SINK

22 BASIC APPROACH HEAT SINK SPACER TOP HEATER UPPER PLATE Tu TEST SAMPLE Tm LOWER PLATE REFERENCE SAMPLE T L BOTTOM HEATER SPACER HEAT SINK AT THERMAL EQUILIBRIUM, Q = [(T U T M ) / (R S + R int )] R S = [(T U T M )/Q] R int (1) WHERE, R S = THERMAL RESISTANCE OF THE TEST SAMPLE (m 2 K/W) R int = TOTAL INTERFACE RESISTANCE BETWEEN SAMPLE AND SURFACE PLATES (m 2 K/W) Q = HEAT FLUX THROUGH THE TEST SAMPLE (W/m 2 ) PLEASE NOTE THE ACTUAL SAMPLE TEMPERATURE NOT MEASURED

23 BASIC APPROACH.. Contd HEAT SINK SPACER TOP HEATER UPPER PLATE Tu TEST SAMPLE Tm LOWER PLATE REFERENCE SAMPLE T L BOTTOM HEATER SPACER HEAT SINK R S = d/λ (2) WHERE, WHERE, d = SAMPLE THICKNESS (m) λ = THERMAL CONDUCTIVITY (W/mK) Q = N (T M T L ) (3) N = REFERENCE CALORIMETER HEAT TRANSFER COEFFICIENT COMBINING EQUATIONS (1) AND (3) R S = F[(T U T M ) / (T M T L )] R int (4) R S = F( T S / T r ) R int EQUATION (4) IS A STRAIGHT LINE EQUATION & F = (1/N) IS THE PROPORTIONALITY CONSTANT

24 EQUIPMENT CALIBRATION WITH DIFFERENT SAMPLES R S = F( T S / T r ) R int A, B, C & D ARE DIFFERENT CALIBRATION SAMPLES

25 CALIBRATION AT DIFFERENT TEMPERATURES

26 TEST RESULTS - VESPEL 0.42 Thermal Conductivity (W/mK) Measured Data Literature Data Temperature ( 0 C) TEMPE RATUR E ( 0 C) MEASU RED K (W/mK) LITERA TURE K (W/mK) % DIFFER ENCE

27 TEST RESULTS STAINLESS STEEL 19 Thermal Conductivity (W/mK) Measured Data Literature Data Temperature ( 0 C) TEMPERA TURE ( 0 C) MEASU RED K (W/mK) LITERAT URE K (W/mK) % DIFFERE NCE

28 TEST RESULTS - PYREX 1.30 Thermal Conductivity (W/mK) Measured Data Literature Data TEMPER ATURE ( 0 C) MEASU RED K (W/mK) LITERA TURE K (W/mK) % DIFFERE NCE Temperature ( 0 C)

29 REPEATABILITY OF MEASURED DATA TEMPERA TURE ( 0 C) RUN 1 K (W/mK) RUN 2 K (W/mK) % DIFFERE NCE PYROCERAM TEMPERATURE ( 0 C) RUN 1 K (W/mK) RUN 2 K (W/mK) % DIFFERENCE VESPEL

30 ACCURACY IN MEASUREMENTS DEPENDS ON THERMAL RESISTANCE OF THE SAMPLE IT ASSUMES R INT REMAINS SAME FOR REFERENCE AND TEST SAMPLES. PRESSURE ON STACK MINIMISES THIS ERROR. ACCURACY IS HIGHEST WHEN R INT IS SMALL COMPARED TO R S R INT IS MINIMISED BY POLISHED METAL SURFACE AND HEAT TRANSFER COMPOUND MINIMUM T THAT PRODUCES ACCURATE RESULTS IS 5 0 C LOW TEMPERATURE LOW RESISTANCE (LTLR), LTHR, HTLR & HTHR HEAT FLUX METERS ARE DESIGNED. SAMPLE THICKNESS IS SELECTED TO ACHIEVE DESIRED R S FOR THE BEST RESULTS.

31 ACCURACY IN MEASUREMENTS..Contd. TEMPERATURE MEASUREMENT SAMPLE THICKNESS MEASUREMENT EDGE LOSSES - FROM SAMPLE TO GUARD ESTIMATED ACCURACIES ARE: 0.1 TO 0.2 W/mK ± 8% 0.2 TO 1.5 W/mK ± 6% 1.5 TO 30 W/mK ± 3%

32 LIST OF OTHER TEST FACILITIES AVAILABLE AT THERMAL/ ISAC THERMAL ANALYSIS SYSTEM DSC, TGA, TMA & DMA THERMAL CONSTANTS MEASURING EQUIPMENT (LFA) UV/ VIS/ NIR SPECTROPHOTOMETER FTIR SPECTROPHOTOMETER OPTICAL PROFILOMETER MULTIPLE BEAM INTERFEROMETER INFRARED EMISSOMETER SOLAR SPECTRUM REFLECTOMETER INFRARED THERMAL IMAGING SYSTEM

33 LIST OF OTHER TEST FACILITIES AVAILABLE AT THERMAL/ ISAC TEMPERATURE SENSORS CALIBRATION FACILITY FACILITY FOR CALORIMETRIC TESTS CRYOGENIC CHAMBER FOR EMITTANCE MEASUREMENT THERMAL COMPARATOR MLI THERMAL CONDUCTANCE MEASUREMENT FACILITY HIGH TEMPERATURE VACUUM DEGASSING FURNACE DILATOMETER FOR LOW THERMAL EXPANSION MEASUREMENT OF LONGER SPECIMENS

34 LIST OF OTHER TEST FACILITIES AVAILABLE AT THERMAL/ ISAC IR SIMULATION FOR TVP/ TBT TESTS SOLAR SIMULATION THERMAL BALANCE TEST FACILITY Ø 9m TVC THERMAL DATA ACQUISITION & CONTROL FACILITY Facilities-1.ppt

35 CONCLUDING REMARKS ALL THE TEST AND MEASUREMENT FACILITIES REQUIRED ARE AVAILABLE UNDER ONE ROOF AT ISRO SATELLITE CENTRE, BANGALORE. FOR EVALUATING/ CHARACTERIZING THE THERMAL CONTROL MATERIALS. FOR CONDUCTING THE THERMAL BALANCE TEST FOR VALIDATING THE THERMAL DESIGN OF THE SATELLITE THERMAL CONTROL SYSTEM. FOR CARRYING OUT THE THERMOVACUUM PERFORMANCE TESTS ON VARIOUS SATELLITES.

36 THANK YOU