Transcript Document

Carbon Dioxide and Moisture
Removal System
NASA ECLSS
July 17, 2002
Team Organization
• Jessica Badger
– Project Coordinator
– Honeycomb structures
• April Snowden
– Team Leader
– Aerogels
• Julia Thompson
– Researcher
– Carbon nanotubes
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• Dennis Arnold
– Researcher
– Honeycomb structures
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Overview
• Space Launch Initiative Program
• Current RCRS Design
– Solid Amine Technology/Ion Resin Beads
• Carbon Dioxide/Moisture Removal System
(CMRS) Design Requirements
• Coeus Engineering’s Design Process
• Possible Designs
– Honeycomb structures
– Carbon nanotubes
– Aerogels
• Future Work
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Space Launch Initiative Program
• Focuses on the future of
exploration and
development of space
• Creation of 2nd Generation
Reusable Launch Vehicle
(RLV)
– Reduce risk of crew loss to
1 in 10,000 missions
– Lower payload cost to less
than $1,000 per pound
– Incorporate latest
technology for CO2 removal
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Current RCRS Design
• 11 layered CO2 adsorbent “beds”
• Alternating active and inactive beds
– Active beds remove CO2
– Inactive beds exposed to vacuum
release CO2
• Dimensions: 3 ft x 1 ft x 1.5 ft
– 70% beds
– 30% controls/valving
• Removes ≈ 0.62 lbs CO2/hour
– 7 member crew
– Requires 26 lbs of solid amine
chemical
– Requires flow rate of 40 cfm
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Current RCRS Design
• Ion resin beads
– Copolymer of
polystyrene and
divinylbenzene
– Sometimes made from
Acrylic
– ≈ 3mm diameter
– Extremely porous
– Coated surface area:
250-350 m2/cm3
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Current RCRS Design
• Hamilton Standard produces solid amines
used in RCRS
• Solid amine chemicals
– CO2 and H2O “loosely” bond to solid amines
– Reaction produces heat
– Common alkanolamine CO2 adsorbents:
– monoethanolamine (MEA)
– diethanolamine (DEA)
– methyldiethanolamine (MDEA)
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Current RCRS Design
• Active/Inactive beds interlayered
– Active beds pressurized and
heated
– Inactive beds cold and
exposed to vacuum
– Large pressure and
temperature gradients
• Aluminum Puffed Duocell
Foam
– Houses ion-resin beds
– Structural rigidity
– Heat transfer properties
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Current RCRS Design
• Channeled air flow
– Each bed contains 4
bead-filled foam
chambers
• Retaining screens
– Prevent beads from
entering main air
stream
– 8 screens per layer
– Create large pressure
drop
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CMRS Design Requirements
• Maximize solid-amine surface area
• Minimize pressure drop through each
bed
• Maximize structural rigidity
• Maximize heat transfer from active to
inactive beds
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Design Process
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Honeycomb Structures
• Packed or joined
together in hexagonal
manner
• Lightweight
• High strength and
rigidity to weight ratios
• Commonly used in
sandwiched structures
– Airliner floors
– Airplane wings
– Motorcycle helmets
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Honeycomb Structures
• Applied in directional
air/fluid flow control
and/or energy absorption
• Available in 5052 and
5056 Aluminum alloys
• Varied cell sizes
– 1/16” - 3/8”
• Can be perforated
– Allows air flow
– Improves heat removal
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Honeycomb Structures
• Various grades can be exposed to
temperatures up to 430 oF
• 5 lbs/ft3
• .0015 nominal thickness
• Provides for about 30.38 in2 surface area per
cubic inch
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Honeycomb Structures
• If coated with chemical,
surface area not
comparable to that of
beads
• Would provide
structural rigidity
• Would provide heat
transfer
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Carbon Nanotubes
Enter the World of
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What is it?
• Discovered by
Sumio Iijima in 1991
• High-resolution
transmission
electron microscopy
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• Fullerene-related
structures
• Consists of
graphene cylinders
closed at either end
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Types of Carbon Nanotubes
• Single-walled
carbon nanotube
– Single sheet of
carbon atoms
– 1 < d < 3 nm.
• Multi-walled carbon
nanotube
– Multiple sheets of
carbon atoms
– d > 3 nm.
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Attributes of Carbon Nanotubes
• Diameter
– Size of nanometers
– 1/50,000th of a human
hair
• Length
– Several micrometers
– Largest is ~ 2 mm
• Each nanotube is a
single molecule
– Hexagonal network of
covalently bonded
carbon atoms
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Super strength
Low weight
Stability
Flexibility
Good heat
conductance
• Large surface area
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– 300-800 m2/cm3
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Mechanical Properties
• Extremely strong
– 10-100 times stronger than steel per unit weight
• High elastic moduli
– About 1 TPa
• Flexible
– Can be flattened, twisted, or bent around sharp
bends without breaking
• Great performance under compression
• High thermal conductivity
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Possible Uses
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Transistors and diodes
Field emitters for flat-panel displays
Cellular-phone signal amplifiers
Ion storage for batteries
Materials strengthener
– Polymer composites
– Low-viscosity composite
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Potential Use for CMRS
• Coat nanotubes with solid amine
– Maximize surface area
• Eliminate mesh retaining screen
– Carbon nanotubes fixed to housing structure
– No need for beads
– Minimize pressure drop
• Nanotube structure to channel air
– Replace aluminum Duocell foam with
aluminum/carbon nanotube composite
– Coat carbon nanotubes with solid amine and fit
into honeycomb or Versacore structure
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What is an Aerogel?
• Critically evaporated gel
• Lightest solid known
• Almost transparent
solid
• Great insulator
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The History of Aerogels
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Samuel Stephens Kistler
A friendly little wager
First publication: Nature 1931
Little done until late 1970’s
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Aerogels as Support Structures
• Young’s modulus:
• Tensile strength:
• Density:
106 – 107 N/m2
16 Kpa
≥ 0.003 g/m3
• Support 1500 times
their own weight
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Aerogels as Insulation
• Examples of use:
– Modern refrigerators
– Mars rover
• 39 times better than best
fiberglass insulation
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Aerogels as High Surface
Area Materials
• Up to 99% air
• Pore size
– Range from
3 nm to 50 nm
– Average about 20 nm
• Effective surface area:
300 – 400 m2/cm3
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Aerogels and Coeus Engineering
• Recap
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Strong
Lightweight
High surface area
Does not require a screen
• Can the aerogel be coated?
• Different base materials
• Place inside honeycomb
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Carbon Nanotubes / Aerogels
Properties
Ion Resin
Beads
Carbon
Nanotubes
Aerogels
Surface Area
250-350
m2/cm3
300-800
m2/cm3
300-400
m2/cm3
Young's
Modulus
N/A
1 TPa
106-107 Pa
Tensile
Strength
N/A
30 GPa
(max)
16 kPa
Cost
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Future Plans
• Wrap-up research
– Nanotubes
– Aerogels
– Carbon nanofoam
• Prepare cost analysis
• Compare and contrast research findings
– Confer with John Graf
• Decide on a final recommendation
• Final presentation and final report
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Special Thanks!!
• Dr. John Graf
• Dr. Ronald O. Stearman
• Marcus Kruger
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Questions?
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Preguntas?
Questionne?
Bопрос?
Kwestie?
Ninau?
Swali?
Spørsmål?
Förhöra?
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