NASA Technical Reports Server (NTRS) 20130013661: CryoCube-1: A Cryogenic Fluid Management CubeSat

2.6 MB·English

by  NASA Technical Reports Server (NTRS)

KEA
CryoCube-1:
A Cryogenic Fluid
Management CubeSat
Jared Berg
CryoCube Project Intro
KSC ENGINEERING
AND TECHNDLDGY:
• CubeSat platform
• Cryogenic fluid management
experiments
- Fluid location sensing
- Slosh characterization
- Cryogenic fluid transfer
• Cooperative effort between
private industry and NASA
• SLI: Design, fabrication,
major component
procurement
• KSC: Analysis, radio
communications hardware
• Principle Investigators
- Jared Berg- NASA
- Phil Putman- Sierra Lobo
2
CryoCube Project Intra
KSC ENGINEERING
AND TECHNOLOGY
• CryoCube-1 (CC-1)
- Liquid oxygen (LOX) working
fluid
- Solid-to-gas generator
- Low temperature experiment
tank
• Instruments
- Cryo-Trackersensor
- In-tank camera
• Features
Combination sun shield I solar
cell array
- Magnet-torquer attitude control
- Majority commercial off the shelf
(COTS) components
• Selected for CubeSat Launch
Initiative (CSLI)
- Launch manifested 2014
3
CryoCube Project Intro
• Goal: Analyze thermal performance of CC-1
Reduce experiment tank temperatures into regime appropriate for LOX
condensation(< 119 K@ 1 MPa)
• Passive cooling only
• Lowweight
Oxygen Phase Plot
• Small size 1o.o
.. _
L
• Investigate design f f -- v / -/ / - / ~/- .-,;-.-;:-·~-
sensitivity to I I --- I ~ ·--
- I I
material and optical
1.00
aca. r-
properties
!. liquid Operating
.........
! Region ..........
..,....,....-
•:I 1-
• Determine effects of •
~··
! /~
different orbit a.
0.100
parameters
• Develop preliminary
operational
0.0100
guidelines 100. 120. 140.
Temperature (K)
4
Energy Balance
KSC ENGINEERING
AND TECHNOLOGY
• Radiation follows Stefan-Boltzmann relation q = EaAI1T4
Albedo
Solar
IR
a =Average albedo of Earth
G= Solar radiation q =Earth IR
5 1R
p = Earth view angle A=Area
at= Solar absorptivity of top Et =Emissivity of top
Ka =Albedo factor (0.664 + 0.521 p- 0.203 p2) T =Temperature
ab =Solar absorptivity of bottom cb = Emissivity of bottom 5
Considerations
• Angular size of Earth
- Like having face 10" away from
55" TV and trying not to look
2Q =136oat h = 500 km
- High relative temperature (250K)
- Sun shield ineffective for Earth IR
• Reflections
- Reflective insulation bounces
radiation into unwanted areas
- Complicated arrangements hard to
visualize mentally
• Materials comparison
- Intuitive "best" choice may not be
optimal
- Absorption and re-emission
6
Design Space
• Actuated doors
- Must expose tank directly to deep space
- Permanently exposed tank absorbs too much Earth IR
Active doors can open in eclipse, closed rest of orbit
- Optical properties of inside and outside of
• Shield
- Rounded edges
- Single regular shield will not block Earth IR
- Large shield, middle mounted tank?
- Double shield?
- Shields can reflect radiation back onto tank
• Tank
- Round or cylindrical?
- Effectiveness of fins
• Isolation between segments
- Material
- Length
7
Current Design
KSC ENGINEERING
AND TECHNOLOGY
• Cylindrical tank
- Better view factor than sphere
- Number of fins optimized
• Double shield
- Blocks all Earth IR in eclipse
- Small stowage space
• Active doors
- Open during eclipse
- Adaptable behavior
- Requires power and control
• Isolation
- Long G-10 standoffs separate
structure
- Multi-layer insulation (MLI)
MLI
between segments
- More complicated structure
8
Results
KSC ENGINEERING
AND TECHNOLOGY
• Pseudo-steady state reached at 100,000-120,000 s from 293K
• Below 119K limit
• Slight cooling trend continues asymptotically
T•nk Chllldown
116.2
290
116
280
115.8
11
270 115.6
I \
260 115.4 ~
\ I \
250 115.2 \ I \
115
240 \ I \
114.8
230 \ I \
\ 114.6
~B.; 222100 \ ~ie~l- 111144..42 \ \ \ I I I \ \ \ I I I
E.E~, 129000 \" ~ 11131.48 \ \ I I \ \ I I
f" 180 ~ 113.6 \ \ I
113.4
\ I \ I
170 I'\ 113.2 \ / \ v
160 \ ..... 113 \ / /
150 112.8 \ / /
\.~-.. 112.6
140 / \ /
'- 112.4
130 \/ \ /
120 ~ ""' -- - ,.. ..... ..... 1-o.. 11121.22 v
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0 22.0 24.0 26.0 28.0 30.0 32.0 111.8
31 31.5 32 32.5 33
Time (hours)
Time (hours)
9
Future Work
• Model refinement
- Adjusting materials, conductors, and geometry based on prototype testing
- Adding additional components
- Adding fully-coupled fluid system model of gas generator system to capture
condensation (Feasibility determined by hand calcs)
• Testing
- Precisely measure heat loads and parasitic sources
- Determine coefficients for contact conduction
• May reduce conduction but increase radiation
- Qualify systems for vacuum operation
• Validation
- Full system testing in vacuum chamber
- Check model accuracy
- Refine margins
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