Advanced Stirling Convertor Testing at GRC · 2013-08-22 · Advanced Stirling Convertor Testing at...
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www.nasa.gov Advanced Stirling Convertor Testing at GRC Presented by: Nick Schifer Sal Oriti Thermal Energy Conversion Branch NASA Glenn Research Center May 1, 2013 https://ntrs.nasa.gov/search.jsp?R=20130014472 2020-04-09T01:57:45+00:00Z
Transcript of Advanced Stirling Convertor Testing at GRC · 2013-08-22 · Advanced Stirling Convertor Testing at...
www.nasa.gov
Advanced Stirling Convertor Testing at GRC
Presented by:
Nick Schifer
Sal Oriti
Thermal Energy Conversion Branch
NASA Glenn Research Center
May 1, 2013
https://ntrs.nasa.gov/search.jsp?R=20130014472 2020-04-09T01:57:45+00:00Z
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Background
Advanced Stirling Radioisotope Generator
• Next generation radioisotope-fueled power system
• Lockheed Martin Space Systems is System Integration Contractor
• Suitable for deep-space or other missions without solar power
• Two dual-opposed free-piston Stirling convertors
• > 20% thermal-to-electric conversion at system level
• 1st use of dynamic energy conversion in space
• Necessitates demonstration of conversion technology long-term performance
ASRG System Schematic
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Background
Advanced Stirling Convertor
• Designed and Manufactured by Sunpower, Inc.
• Development initiated in 2004 via NASA technology development contract
• 6 stages of development:
1. ASC-0
2. ASC-1
3. ASC-1HS
4. ASC-E - First Engineering Unit design
5. ASC-E2 - Engineering Unit design with high-temp heater head
6. ASC-E3 - Pathfinder for Flight Unit production
ASC-E3 as-built hardware
Technology Development
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Test Methodology
Three types of tests are performed:
1. Performance Mapping
• Simulate range of expected operating temperatures
• Max/Min thermal input, max/min sink temperature
2. Durability Tests
• Demonstrate and quantify margin of ASC design
• Start/stop cycling, static acceleration, launch vibration, overstroke
3. Extended Operation
• Goal : 10s of thousands of hours
• 24/7, unattended operation
Implementation
• Electric heat source for heat input
• Laboratory circulator for heat rejection
• Automated data system
• Automated shutdown routines
• Thermocouples, thermistors for temperature
• Power meters for voltage, current, power
• LabView data acquisition software
ASC Operation Schematic
Electric Heat
Source
Cold End
Hot End
Alternator
Fluid Flow
Electrical Output
Thermal Input
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Test Article Design
Previous test article designs needed improvement :
• Unify convertor test configuration between Sunpower and GRC locations
• Reduce thermal insulation losses
• Eliminate radiation heat transfer paths for more accurate finite element modeling
• Improve temperature measurements for more accurate modeling
• Improve electric heat source life
Heaters protruded through insulation
ASC-E2 Test Article Deficiencies
Air gaps (radiation heat transfer)
Square housing (non-axisymmetric)
Limited life heat source (~2500 hrs)
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ASC-E3 Test Article
Heater lead wires (small conduction path)
ASC-E3 Test Article External View
ASC-E3 Test Article Internal View
Compressible insulation Circular form factor
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Improvements:
• Minimized heater lead losses
• Circular, axisymmetric insulation
• Air gaps filled with compressible insulation
• Longer life heat source (better cartridge fit, lower heat flux)
• Additional temp measurements throughout
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Gap-Filling Insulation
Thermocouple Locations
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• Auxiliary thermocouples are required for thermal model
• Embedded in insulation before assembly – more accurate placement
• Aligned with isotherms to reduce disturbance of object temperature
Example auxiliary thermocouple installed in
microporous insualtion piece
Placed along an isotherm to reduce local
temperature disturbance
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ASC-E3 Temperature Measurements
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7 kHz
7 kHz
Alternator
Power Meter
Heat Distributor
Heater Power
Meter
V+
V-
I
AC Bus
Power Meter V+
V-
I Piston
Position
Sensor
Processor
PID Temp Controller
DC Power Supply
Pearson Coils
Net Heat Input
(calc)
AC Power Supply
(variable freq.)
High-rate voltage
and current
waveform archival
Capacitor
Load
High-rate piston
position
waveform
archival
V-
V+
Alternator Housing Temp
Surface TCs
Thermistors
Cold End Temp
TC probes
Thermistors
Hot End Temp
TC probes
Heat Source Temp
TC probes
ASC-E3 Performance Measurement Instrumentation
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ASC-E3 Test Station
ASC-E3 Test Station
Circulators Cold-end temp control
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• Simultaneous operation of a pair of convertors
• Vertical orientation
• Independent operating condition control
2 Convertors Side-by-side
Vertical orientation
Test Rack Data acquisition
Monitoring Operating point control
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ASC-E3 Data Archival and Processing
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• Centralized storage of data from all test stations
• All parameters measured and recorded every 2 seconds
• 5-minute-window average point stored each hour
• Dynamic data sampled and stored at 7 kHz
• Operator notes stored in an event log
Test Rack
Data Server
6TB array
RAID5
2-sec data
5-min avgs
Event log
20 TB array
RAID5
Daily Transfer
Ethernet
7 kHz data
50 GB/hr
Matlab plotting script
• Automated 24-hr plot generation
• User-customizable plotting options
• Automatic population of operator notes on time axis
• Automatic plot naming and storage
• Engineers can examine plots to analyze
performance
Daily
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75
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90
95
100
#2
Alt
FT
Pw
r(W
e)
0 5 10 15 20 2560.0
65.0
70.0
75.0
80.0
85.0
90.0
95.0
100.0
Hours
#1
Alt
FT
Pw
r(W
e)
ASC-E3 #1 & #2Sat 2013-Mar-09 00:00:00Sat 2013-Mar-09 23:59:58
#1 Alt FT Pwr(We)
#2 Alt FT Pwr(We)
National Aeronautics and Space Administration
ASC-E3 Operational Data
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ASC-E3 #1 & #2 runtime each > 2,000 hrs
• No instabilities observed over a range of operating conditions
• No signs of heat source failure
• Daily 2-second data plots show steady operation
0
10
20
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60
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90
100
#2 A
lt F
T P
wr(
We)
0 200 400 600 800 1000 1200 1400 1600 1800 20000
10
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90
100
Hours
#1 A
lt F
T P
wr(
We)
ASC-E3 #1 & #2
Fri 2013-Jan-25 11:43:00
Thu 2013-Apr-11 06:00:00
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Plot of hourly 5-minute averages over 1,800 hours
Various operating conditions
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ASC Operation Summary
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ASC Model # Units Total Runtime Status
ASC-0 4 92,000 Ongoing
ASC-1 2 3,700 Ongoing
ASC-1HS 2 11,000 Complete
ASC-E 4 100,000 Ongoing
ASC-E2 8 54,000 Ongoing
ASC-E3 2 4,000 Ongoing
Total = 263,900
