Transcript Document

Carbon Dioxide and Moisture
Removal System
Team Organization
• Advisor: Dr. John Graf, NASA ECLSS
• Jessica Badger
– Project Coordinator
– Aerogels
• April Snowden
– Researcher
– Carbon nanotubes
08-14-02
• Dennis Arnold
– Team Leader
– Aerogels
• Julia Thompson
– Researcher
– Honeycomb structures
Coeus Engineering
2
Overview
• Space Launch Initiative Program
• Current RCRS Design (Recap)
• Carbon Dioxide/Moisture Removal System
(CMRS) Design Requirements
• Materials Researched
– Honeycomb structures
– Carbon nanotubes
– Aerogels
• Project Specialization
– Pressure drop Analysis through aerogel
• Summary/Conclusions
08-14-02
Coeus Engineering
3
Space Launch Initiative Program
• Focuses on the future of
exploration and
development of space
• Creation of 2nd Generation
Reusable Launch Vehicle
(RLV)
– Lower payload cost to less
than $1,000 per pound
– Incorporate latest
technology for CO2 removal
08-14-02
Coeus Engineering
4
Current RCRS Design
• 12 layered CO2 adsorbent “beds”
– 6 layers per bed
• Alternating active and inactive layers
– Active layers remove CO2
– Inactive layers exposed to vacuum to
release CO2
• Dimensions: 3 ft x 1 ft x 1.5 ft
• Removes ≈ 0.62 lbs CO2/hour
– 7 member crew
– Requires 26 lbs of solid amine
chemical
– Requires flow rates of 20 - 40 cfm
08-14-02
Coeus Engineering
5
Airflow Diagram of RCRS Layer
• 4 bead-filled foam
chambers per layer
• Retaining screens
– Prevent beads from
entering main air
stream
– 8 screens per layer
– Inlet and outlet
– Create large pressure
drop due to blockage
at outlets
08-14-02
Coeus Engineering
6
Specific RCRS Components
• Ion-Resin Beads
– Copolymer of polystyrene and
divinylbenzene
– ≈ .3mm diameter
– Extremely porous
– Coated surface area:
250-350 m2/cm3
• Aluminum Puffed Duocell
Foam
– Houses ion-resin beds
– Structural rigidity
– Heat transfer properties
08-14-02
Coeus Engineering
7
Solid-Amine Chemicals
•
•
•
•
CO2 and H2O “loosely” bond to solid-amines
Can be “coated” onto certain materials
Air + solid-amine reaction produces heat
Common alkanolamine CO2 adsorbents:
– monoethanolamine (MEA)
– diethanolamine (DEA)
– methyldiethanolamine (MDEA)
08-14-02
Coeus Engineering
8
Julia Thompson
CMRS Requirments
Honeycomb Structures
08-14-02
Coeus Engineering
9
CMRS Design Requirements
• Maximize solid-amine surface area
• Maximize structural rigidity
• Maximize heat transfer from active to
inactive beds
• Minimize pressure drop through each
bed
08-14-02
Coeus Engineering
10
Materials Researched
Structural Rigidity
&
Heat Transfer
Surface Area
&
Pressure Drop
Aluminum
Honeycomb
Carbon Nanotubes
&
Aerogels
08-14-02
Coeus Engineering
11
Overview of Honeycombs
• Packed or joined
together in hexagonal
manner
• High strength and
rigidity to weight ratios
• Commonly used in
sandwiched structures
– Airliner floors
– Airplane wings
– Motorcycle helmets
08-14-02
Coeus Engineering
12
Use of Honeycomb in CMRS
• Applied in directional
air/fluid flow control
and/or energy absorption
• Available in various
Aluminum alloys
– 2024-T81P
• Varied cell sizes
– 1/4”
• Perforated
– Allows three-dimensional
air flow
– Improves heat removal
08-14-02
Coeus Engineering
13
Use of Honeycomb in CMRS
• Grade C: Alloy 2024-T81P
– Perforated
– Hardened
– Chemically treated for erosion protection
• 3 lbs/ft3
• Total weight of honeycomb in system = 5 lbs
• 30 in2 surface area per cubic inch
– more surface area = more heat removed
08-14-02
Coeus Engineering
14
Use of Honeycomb in CMRS
• Structural Rigidity
– Grade C honeycomb
provides more
structural rigidity than
Grade B.
– T81 more rigid than T3
• Airflow
– 3 dimensional
– More air in contact with
solid amine
08-14-02
Coeus Engineering
15
Honeycomb vs. Duocell Foam
• Heat transfer not a
problem
• Strength tests
– Layers must be built,
pressurized.
• Manufacturing of
layers
– Weld/Bond plates to
core
– Filling with chemical
• Less area taken up by
aluminum structure
08-14-02
Coeus Engineering
16
April Snowden
Carbon Nanotubes
Aerogels
08-14-02
Coeus Engineering
17
Carbon Nanotube Attributes
• 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
08-14-02
•
•
•
•
•
Super strength
Low weight
Stability
Flexibility
Good heat
conductance
• Large surface area
Coeus Engineering
– 300-800 m2/cm3
18
Carbon Nanotube
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
08-14-02
Coeus Engineering
19
Carbon Nanotube Possible Uses
• Transistors & diodes
• Field emitters for flatpanel displays
• Cellular-phone signal
amplifiers
• Ion storage for batteries
• Materials strengthener
– Polymer composites
– Low-viscosity composite
08-14-02
Coeus Engineering
20
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
– Replace aluminum Duocell foam with
aluminum/carbon nanotube composite
08-14-02
Coeus Engineering
21
Aerogel Attributes
• Critically evaporated gel
• Lightest solid known
• Almost transparent
solid
08-14-02
Coeus Engineering
22
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
08-14-02
Coeus Engineering
23
Aerogels as High Surface
Area Materials
• Up to 99% air
• Pore size
– Range from
3 nm to 50 nm
– Average about 20 nm
– Allows O2 and N2 molecules to flow through
• Effective surface area: 300 – 400 m2/cm3
• Possible Use
– Replace ion resin beads
08-14-02
Coeus Engineering
24
Ion-Resin Beads / Carbon
Nanotubes / Aerogels
Properties
Surface Area
Ion Resin
Beads
Carbon
Nanotubes
Aerogels
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
08-14-02
Coeus Engineering
25
Dennis Arnold
New Design Plan
Analysis of New Design
08-14-02
Coeus Engineering
26
Project Specialization
• Focused on use of aerogels in CMRS
– Time constraints
– Amount of readily available information
– Nanotubes are in early development
stages
– NASA currently researching nanotubes
08-14-02
Coeus Engineering
27
Aerogels Replacing Beads
• Issue of pressure drop through chambers full
of aerogel
• Discussed issue with Dr. Noel Clemens
– Aerogels would result in lack of sufficient airflow
– Decided NOT to replace the beads with aerogel
• Decided to keep the beads, replace screen
• Concluded to research replacing the mesh
screen with a thin slice of aerogel
08-14-02
Coeus Engineering
28
Aerogels Replacing Mesh Screen
• Air flow is choked by
the beads at the outlet
retaining screen
08-14-02
Coeus Engineering
29
Aerogels Replacing Mesh Screen
• Theoretically, air flows around the beads and
through the aerogel slice without blockage
08-14-02
Coeus Engineering
30
Aerogel Pressure Drop Analysis
• Start with Darcy’s Law:
KPA
Q
L
Q = volumetric flow rate
K = permeability
A = area perpendicular to flow
L = length of flow across medium
∆P = Change in pressure across medium
08-14-02
Coeus Engineering
31
Pressure Drop Analysis (Cont)
• Rearranged into slope-intercept form:
 P  1  Q 

  
 L  K A
• Which resembles
m = slope
b = y-intercept
08-14-02
y  mx  b
Coeus Engineering
32
Pressure Drop Analysis (Cont)
• Estimated
slope from
figure
• Slope = 1/K
08-14-02
Coeus Engineering
33
Pressure Drop Analysis (Cont)
• Solving Darcy’s law for ∆P:
QL
P 
KA
Q = 20 cfm
L = 0.15 x 21/2 in.
⃘
A = 3 ft. x 1.25 in. x Cosine 45
K = 1.8 x 106 g/cm3 – s2
∆P = 3.7 in H2O
08-14-02
Coeus Engineering
34
Pressure Drop Analysis (Cont)
Pressure Drop Through Bed and Headers
Pressure Drop (in H2O)
12
10
8
Bed A Data
Bed B Data
6
4
2
0
0.0
10.0
20.0
30.0
40.0
Flow Rate (CFM)
08-14-02
Coeus Engineering
35
Jessica Badger
Summary
Conclusions
08-14-02
Coeus Engineering
36
Summary
• Heat Transfer and Structural Rigidity
– Replace aluminum puffed foam with perforated
honeycomb (2024 - T81P)
– Cell size = 0.25”
– Provides 3-D airflow through bed
– Adds strength and rigidity due to high strength-to-weight
ratios
– Allows the beads to be more densely packed into the
structure
– Heat removed via radiation
– Rate at which heat is removed is comparable for both
perforated honeycomb and puffed foam
08-14-02
Coeus Engineering
37
Summary (cont)
• Surface Area & Pressure Drop
– Studied carbon nanotubes and aerogels for ways to
replace ion resin beads
– Considered filling each perforated honeycomb cell
with solid-amine coated aerogel
– Air would not be able to flow through
– Needed a new design strategy
– Decided to use thin slice of aerogel to replace outlet
retaining screens
– Pressure drop for single slice of aerogel was comparable to
entire RCRS bed
– Needed more recent aerogel permeability data
08-14-02
Coeus Engineering
38
Conclusions
• Replace aluminum puffed foam with
perforated honeycomb
• Further investigate aerogel properties
and possible use
• Research previous option of carbon
nanotubes for solid-amine housing
08-14-02
Coeus Engineering
39
Special Thanks!!
•
•
•
•
•
Dr. John Graf
Dr. Ronald O. Stearman
Dr. Noel Clemens
Dr. Arlon Hunt & Dr. Ulrich Schubert
Marcus Kruger
08-14-02
Coeus Engineering
40
Questions?
•
•
•
•
•
•
•
•
Preguntas?
Questionne?
Bопрос?
Kwestie?
Ninau?
Swali?
Spørsmål?
Förhöra?
Please visit our website at www.ae.utexas.edu/~juliat
08-14-02
Coeus Engineering
41