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System Schematic HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
HyPerPLSS:
Development of a Single-Fluid Consumable
Infrastructure for Life Support, Power,
Propulsion, and Thermal Control

1
Dr. David Akin
Craig Lewandowski
Dr. Carol Smidts
Jinny McGill HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
Presentation Outline
Background and Concept Overview
Dr. David Akin
Chemistry, Thermodynamics, and Components
Craig Lewandowski
Reliability and Risk Analysis
Dr. Carol Smidts
Jinny McGill
System Applications
Dr. David Akin
2 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
EVA Life Support Background
Portable life support
system (PLSS) required
for unrestricted
extravehicular operations
(EVA)
Supplies oxygen, power,
cooling
~120 lbs (Earth) weight on
back
3 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
Apollo PLSS Internal Layout
4 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
Genesis of the Concept
Current PLSS recharge requires battery
replacement, water refill, high pressure oxygen
recharge, contamination control cartridge
replacement - each with external support
requirements
Observe that 2 H
2
O
2
2 H
2
O + O
2
+ heat
Hydrogen peroxide (room temperature liquid)
might be able to supply all requirements for life
support Hydrogen Peroxide PLSS
HyPerPLSS
5 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
H2O2 Requirements
Assumed requirements
0.6 kg O2
5 kg of H2O
800 W·hr of electrical
energy
88.5% => minimum mass (chemistry only)
Increased to 95% to generate enthalpy needed
by power system (thermodynamics added)
Required H2O2 mass = 10.9 kg
6 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
System Schematic
7 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
Component Description
2.10 gallon tank
Protection against freezing
Band heater
Temperature sensor
Flow adjusted with varying demand
requirements
Pump
Throttle valve
8 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
H2O2 Catalyst Bed
Significant knowledge base exists for H2O2
propulsion
SOA: Silver-based catalyst beds
General Kinetics Inc. COTS product
Silver screens
L = 3.3 in, D = 0.75 in
Ensure H2O2 decomposition by
increasing residence time
H2O2 Gas Generator
(www.gkllc.com)
9 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
Power System
Convert thermal energy to
electricity
Stirling engine
Sunpower ASC COTS system
80 W, 36% efficiency
H2O to generate temperature
gradient
Battery provides and stores
excess energy
Sunpower ASC
(Wong et.al)
10 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
Sublimator and Supply Loops
Sublimator overview
Phase changes
Heat removal
HyPerPLSS fluids
H2O phase change
Cooled streams
Water separator
Conventional supply
loops
11 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
Reliability and Risk Analysis Motivation
Inform design decisions with considerations of
reliability and risk
Increase reliability of system
Decrease risk of design
Consider hazards to equipment and crew health
Hydrogen peroxide can cause spontaneous combustion with
organic materials and is incompatible with many metals (e.g.,
iron, copper, brass, silver, zinc).
Corrosive to skin, membranes, and eyes at high
concentrations.
Vapors from concentrated solutions of hydrogen peroxide
can result in significant morbidity.
12 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
Parallel Process
Conceptual design
Reliability analyses
Failure Modes and
Effects Analysis
Fault Tree Analysis
Parallel process with
feedback between
design and analyses
Reliability and
Risk Analyses
Design
13 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
Failure Modes and Effects Analysis
Technique for reliability analysis
Describes failure causes and effect on system
Results are used to consider design changes
that may be necessary to reduce unreliability
and risk
14 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
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Failure Modes and Effects Analysis
Failure Modes
Manner of the failure
Tumer et al. (5) provides an
updated failure mode
taxonomy
Severity
Qualitative rating assigned
for the worst possible effect
MIL-STD-1629A severity
levels were modified to
differentiate between Loss of
Crew and Loss of Mission
15 HyPerPLSS Phase I Report
NIAC Phase I Fellows Meeting
U N I V E R S I T Y O F
MARYLAND
Fault Tree Construction
The top level event is the undesirable event (e.g., system
failure)
Lowest level events are basic events (e.g., component failure)
Boolean logic gates are used to communicate event effects on
the system
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MARYLAND
Fault Tree Analysis
The Boolean expression for the fault tree is
written, then expanded
This expression is simplified (i.e., Boolean
reduction) to achieve the simplest logical
expression from which the minimum cut sets can
be obtained
Birnbaum importance measure represents the
change in system risk with respect to changes in
basic event probabilities
17 HyPerPLSS Phase I Report
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Event Tree
18 HyPerPLSS Phase I Report
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MARYLAND
Quantification
Fault tree analysis gives qualitative results in the form
of cut sets; quantitative results can also be obtained
Probabilities (or frequencies) of basic events are used
to compute probability of top level events
Failure probabilities (or frequencies) can be obtained in
several ways:
Databases of component failure frequencies
Expert elicitation
Human Reliability Analysis Models (e.g., THERP)
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Scope of Analyses
Operation phases/modes for HyperPLSS include and are
not limited to:
Storage for launch
Maintenance
Power operation
Analyses thus far have focused primarily on the power
operating mode during EVA
Direct functional dependencies are considered in the
FTA; common cause failures have not been considered
20 HyPerPLSS Phase I Report
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MARYLAND
Scope of Analyses
Several system aspects are not yet modeled in detail
Electrical system
Piping system
Stirling engine
Packaging structures and insulation
Software (control system)
Failure is assumed rather than degraded states
Qualitative analyses only thus far (no probabilities or
frequencies have been applied yet)
Risk analysis has been limited to a review of the hazards
of hydrogen peroxide to health
21 HyPerPLSS Phase I Report
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FMEA Example
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Fault Tree Example
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Fault Tree: Cut Sets
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Fault Tree Example
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Comments about the Process
For systems where reliability and risk are of concern,
these analyses should be performed in parallel with
design
Such a parallel process requires that a structured
approach be taken; configuration control can become an
issue during conceptual design p