The Advanced Stirling Radioisotope Generator (ASRG) will enable various missions such as small body sample return, atmospheric missions around Venus, as well as long - duration deep space missions. Analysis of the temperature distributions are performed on an Advanced Stirling Convertor, and the results are compared with available experimental measurements. This analysis includes applied environmental conditions that are similar to those that will be experienced while the convertor is in operation. The applied conditions represent a potential mission profile including pre-takeoff sterilization, launch, transit, and return. The results focus on the anticipated peak temperatures of the magnets in the linear alternator. These results confirm that the ASC can support future missions to deep space targets, extreme environment landers, as well as more conventional goals

Dyson, Rodger W.

Reid, Terry V.

Objectives of this work are: (1) Assist the Science Mission Directorate in developing technologies for space missions. (2) Explore the capability of computational modeling to assist in the development of the Advanced Stirling Convertor. (3) Baseline computational simulation with available experimental data of the ASC. (4) Calculate peak external pressure vessel wall temperatures and compare them with anticipated values. (5) Calculated peak magnet temperature inside the ASC over a range of operational scenarios

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National Aeronautics and Space Administration
Thermal Performance Expectations of the 
Advanced Stirling Convertor Over a Range of 
Operating Scenarios
Presented at the 8th International Energy Conversion Engineering Conference
Nashville, TN
July 25 – 28, 2010
Terry V. Reid
Rodger W. Dyson
Thermal Energy Conversion Branch
NASA Glenn Research Center
Cleveland Ohio
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
https://ntrs.nasa.gov/search.jsp?R=20110011189 2019-08-30T15:25:19+00:00Z
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National Aeronautics and Space Administration
OBJECTIVE
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
- Assist the Science Mission Directorate in developing technologies
for space missions.
- Explore the capability of computational modeling to assist in the
development of the Advanced Stirling Convertor.
- Baseline computational simulation with available experimental
data of the ASC.
- Calculate peak external pressure vessel wall temperatures and
compare them with anticipated values.
- Calculated peak magnet temperature inside the ASC over a range
of operational scenarios.
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BACKGROUND
- Radioisotope power system are an effective source of power for missions
that are far from the sun.
- Radioisotope power systems provide on-board power for various deep
space missions.
Pioneer  Includes explorations of Jupiter and Saturn
Voyager  Includes explorations of Neptune
Cassini  Includes explorations of Saturn’s rings
Galileo  Includes explorations of Jupiter
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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National Aeronautics and Space Administration
BACKGROUND
Kuiper Belt Object Orbiter Advanced Stirling Radioisotope Generator
- Deep space probe configurations have been examined to explore
the Kuiper Belt
- Configuration includes 140W ASRG.
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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National Aeronautics and Space Administration
BACKGROUND
ASRG Testing at the NASA GRC Stirling Lab
Advanced
Stirling
Convertor
- 140 W ASRG currently tested at NASA GRC.
- ASRG is equipped with two ASC convertors.
- Testing includes different hardware versions of ASC
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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- Node Count: 374 processors, 160 channel Clos
network
- Fiber optic 1.28 Gb/s Bi-Directional, 600 ns 
latency
- Chip Design: AMD Opteron 250 & 850, 2- & 4-
Way
- Peak Floating Point Performance: 1.795 
TeraFlops
- Total Memory: 4 Terabytes, Total Disk: 31.5 
TeraBytes
•Utilizes 75 KVA Power and 20 Ton Cooling
CLUSTER
NASA GRC Cluster with Myrinet
Fiber Optic  Communications
8-port “leaf “ level of switching 
in Clos network
128 port Myrinet Clos fiber 
Optic network switch
Clos Network
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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MODEL
- Stirling cycle occupies head of the device. Hot-end temperature (from heat input
 red) and cold-end temperature (from heat removal blue) results in displacer
and piston motion.
- Cyclic motion of piston moves a magnet adjacent to an alternator, creating an
electric field.
- 2D (750,000 grid points); 3D (8.2 million grid points)
Free-Piston
Stirling Linear
Alternator
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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METHODOLOGY
1) Run simulation using steady Navier Stokes equations until solution
is converged.
Boundary conditions
• Net heat input (or hot-end temperature) on the heater head.
• Heat removal (or cold-end temperature) at the cold side adapter flange.
• Heat generation due to linear alternator losses (operating convertor).
• Radiating external wall to a remote environment at a temperature 25 C
lower than the cold-end temperature.
2) Run unsteady Navier Stokes equations for 10 cycles until solution is
time periodic.
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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BOUNDARY CONDITIONS
Heat input: Ranges from 180 to 208 Watts.
Heat rejection at CSAF: Removal rate up to 150 W.
Coil Heat generation: Aimed at simulating linear alternator losses
during the conversion of mechanical power to electrical power.
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
Net Heat Input
QNET
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BOUNDARY CONDITIONS
Linear Alternator Losses
Eddy Losses
Hysteresis Losses
Applied all losses in computational model as heat generation terms in LA coil
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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RESULTS – Comparison with lab data
Free-Piston
Stirling
Linear 
Alternator
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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RESULTS – Varying coil heat generation
Free-Piston
Stirling
Linear
Alternator
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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RESULTS – Varying cold-end temperature
Free-Piston
Stirling
Linear
Alternator
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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RESULTS – Various operating conditions
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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RESULTS – Various operating conditions
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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National Aeronautics and Space Administration
SUMMARY
- When conditions from the operating ASC-E were applied to the
computational model, the calculated peak pressure vessel exterior
wall temperature was within 1.5 C of the test article.
- A 1 Watt increase in coil heat generation rate resulted in a 1.4 C
increase in peak temperature on the pressure vessel external surface.
- As the cold end temperature is increased, the ∆T between the peak
PV wall and the cold-end decreases when coil heat generation is
kept constant.
- While further enhancements are planned, the computational model
should have enough fidelity to investigate the complex internal flow
physics and heat transfer in the ASC-E2.
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGEMENTS
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National Aeronautics and Space Administration
ACKNOWLEDGMENTS AND DISCLAIMER
TITLE
OBJECTIVE
BACKGROUND
CLUSTER
MODEL
METHODOLOGY
BOUNDARY CONDITIONS
RESULTS
SUMMARY
ACKNOWLEDGMENTS
The authors would like to thank the Science Mission Directorate,
and the Radioisotope Power System Program office, in addition to
numerous others.
The information contained in this presentation was generated at the
NASA Glenn Research Center
Any opinions, findings, results, conclusions, or recommendations
expressed in this presentation are those of the authors and do not
necessarily reflect the views of the National Aeronautics and Space
Administration.


Thermal Performance Expectations of the Advanced Stirling Convertor Over a Range of Operating Scenarios

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