7/31/2019 Poster Carpenter Revision 10.24.12
1/1
mal and Cryogenic Testing
ms Development
penter
StateUniversity Los Angeles
ulsion Laboratory
o Urquiza Ph.D., P.E.
ct:
model, fabricate, setup, conduct and analyze thermal and
cryogenic test results for several current JPL projects.
tra Compact Imaging Spectroscopy (UCIS):
y the eective thermal conductance of a data cable to enable
optimization of tactical cryocooler use in future systems.
rborne scanning MultiSPectral Infrared instrument (AirMSPI):
nd run a test to determine whether normal operating thermal
stresses on a silica lter will result in epoxy failure and
delamination of
rs within the silica lter.
ars Atmospheric Trace Molecule Occultation Spectrometer
(MATMOS):
interface parts in Solidworks for the physical connection
between the radiator, thermal strap and load; and created a LabVIEW
data
ion graphical user interface for the test data characterizing
the cooling system thermal performance.
Sounding Oceanographic Lagrangian Observer Thermal RECharging
(SOLO TREC):
nduct testing of the accumulator portion of the power generation
subsystem for the SOLO TREC Submersible that derives its power
from
nging thermoclines of sea water. Tasks include implementing
improvements to the power generation subsystem, to increase
reliability
ime.
ce to NASA:
one of the projects will be going into space any time soon, both
AirMSPI and SOLO TREC will be utilized on active NASA missions in
the
ure. During this internship MATMOS lost its funding when NASA
pulled out of the European Space Agencys ExoMars Trace Gas
Orbiter
ated to launch in 2016. But the technology is good and the
results of the thermal vacuum test should help to sell the
technology for
rojects. UCIS is still in its infancy, but could very well end
up on a future rover, or utilizing a small space on a satellite to
conduct
ents.
e:
engineer it was my goal to quickly set up and conduct tests
pertaining to the performance of parts and systems under
working
ons. I will discuss each of my projects individually to better
illustrate my work.
Methods:
S project ts many applications, from an airborne or ground based
spectroscopy instrument to future applications in a small space
on
rcial satellites or a rover on other planets or moons. In the
current conguration it was found that there was a heat leak that
required a
tactical cryocooler to maintain the desired temperature of 150K.
This means there was an unaccounted for heat source.
etermined that this was probably through the data cable that
communicates to the exterior instruments. UCIS is currently used in
the
here in places like Death Valley, so it is safe to say there is
at least a 150K temperature dierence between the ends of the cable.
UCIS is
d as an inexpensive alternative to past por table Spectrometers,
therefore a pre made cable was used, this while saving cost meant
it
ot be designed for the specic application and properties
sought.
an un-quantied amount of copper being used sandwiched with
Kapton, a polyamide that is stable at a large range of
temperatures
s not outgas in a vacuum. This precludes the ability to
calculate the conductance based on pure material properties and
necessitates a
he working conditions to get an overall conductance of the
complete cable. This will allow the right sizing of the tactical
cryocooler in
re to keep cost and power consumption down.
Target Focus
odeling the cable in Solidworks, I designed a test that would
give me the eective conductance of the cable. Conductance is
the
t of heat (watts) over temperature drop (kelvin), therefore, I
had to nd a way to accurately measure the heat rate input in watts
and the
ature on either end of the strap. We are only interested in the
conductance so the other forms of heat transfer need to be negated
as
possible. To negate the eects of convection, the mean free path
between particles in the surrounding has to be greater than the
size
st chamber. To achieve this, a vacuum chamber at 10^-6 Torr will
give a mean free path between particles much greater than the
whole
chamber. To minimize radiation, a Multi-Layer Insulation (MLI)
blanket is used so the vast majority of radiation heat is returned
to the
is also used to block any view of the cold sensor end of the
assembly. This way we can assume that the applied watts are going
into and
the data cable.
uce the temperature dierence between the two ends, a cryocooler
is used on the sensor end of the cable. It can reach temperatures
as
0K so heat lift must be provided. To accomplish this, four 25W
heaters are used each at 50ohms. The heaters are on two dierent
circuits
ater in parallel, cutting the resistance to 25ohms per circuit,
using a 50V power supply this gives a maximum of 100W of heat per
circuit.
heat lift to maintain temperatures so much higher than the 40K
the cold head is designed for.
h thermal modeling in Solidworks, I determined that in order to
get a fairly even temperature distribution on the sensor end of the
cable,
quarter inch piece of 6061 aluminum would be sucient. For each
of the three data out plates a 5W heater would suce on a three
piece of 6061 aluminum. In all cases, a one eighth piece of 6061
aluminum is used as a compression backing using indium to
increase
mal connection then they are compression t securely
together.
Computer Models
ee data out cables are then hung from manganin wires. At
Cryogenic temperatures which are 150K or below, silicon diodes
provide the
mperature reading using phosphor bronze wires to minimize heat
leak. By curve tting the resistance change across the diode as
a
n of temperature, curves have been developed to get temperature
readings. By applying a known current, then reading the voltage
he diode, the resistance can be determined, (R=V/I) input that
into the cur ve function and an accurate temperature reading is
generated.
ecting the diodes to a Lakeshore temperature reader these
temperatures are read constantly with the right curves applied. By
placing
on diode at each of the edges of the kapton/copper cable the
temperatures can be monitored. After the sensor end is stabilized
at
nd the data out ends at 300K. The voltage is read across the
resistance heaters and also from either side of an installed shunt
resistor of
ute known resistance. The actual current can be determined for
each heater by dividing the voltage over the shunt by its known
ce. By squaring the current and multiplying by the resistance of
the heaters the power can be determined. By adding up these powers
in
iding by the temperature dierence the eective conductance is
determined.
Test Setup
time I set up the experiment and measured the resistance of each
of the data out heater circuits, I found that there was an increase
of
ce of 9ohms from the manganin wire. This would not be a lot
except that the 5W heaters I had on hand were only 25ohms of
resistance.
the stage for large joule heating losses through the manganin
wire that would be impossible to accurately predict if it was going
into
e or not. So 500ohm resistors were ordered to be
over-nighted.
ings are as follows
ctive Conductance is:
K) Conductance
009897
010112525
012046678
009959191
owing data shows the results from the eective conductance test.
The heater power (W) is calculated by P=I^2 R using the current
y reading the voltage across a shunt resistor than dividing that
by the known resistance of the shunt. The heaters are at 300K
roughly
mperature where there resistances should be the same as measured
at room temperature.
data and graphs:
150k data point this is the data from two dierent days and also
hours apart.
ductance and total power through the strap vary only slightly
supporting the integrity of the data. The dierence in conductance
of the
st stabilized readings is = 7.36x10^-4(mW/K)
erence in total heat is = 0.599(mW)
g readings periodically it was possible to check the convergence
of the change in temperature on zero.
a denite convergence but not at zero, looking at the sensor
plate there is a slight temperature increase that is tapering o as
shown.
e sensor plate stabilized the data out ends of the cable should
converge towards zero.
ctive conductance at the time of data collection for this period
changed by 2.09x10^-4(W/K) or 0.046% therefore even without
total
ation this is fairly accurate. The total power also changed by
2.76x10^-4(W) or 0.0038%, unless a greater accuracy then that is
desired
nt is good.
170K:
For this data point the temperature change over time converged
nicely towards zero leading me to believe it was a good data point.
Unfortunatelyas demonstrated by the up oscillations of the data
that the transient eects had not subsided making this an outlying
data point.
180K
For this data point the temperature change over time converged
nicely towards zero conrming the accuracy of the data.
Airborne scanning MultiSPectral Infrared instrument
(AirMSPI):
This project utilizes a specially made silica lter. The lters
are on layers between the silica glass. The whole thing is epoxied
together using an
epoxy with a similar clarity and refractive index as the silica.
It was found through calculations that, due to the dierence in
coecients of thermalexpansion thermal stresses would form. The
operating temperature of the sensor is 200K at that temperature
using the listed specications for the
epoxy and silica there was a chance that the lter would
delaminate. These specications where for properties at room
temperature and probablyhave an unspecied factor of safety,
therefore a test would let us know for sure if delamination would
occur under operating conditions.
Test SetupI created the through ports into the vacuum chamber,
cables and connections for the heaters and the silicon diodes. I
also tested the system for
control because we wanted only to test the ability of the lter
to handle the thermal stress of the operating temperatures not that
of an abrupt
temperature change. After an eective dry run, the lter was
incorporated and I ran the test again with a slow cool down and
warm up.
Test Setup
After plotting the results of the temperatures over time the
lter was sent to be checked with an electron microscope. It did not
delaminate, thebest case for everyone involved.
Test Results
Using the same setup we also categorized the conductance of a
exible strap made of pyrolytic graphite sheet (PGS). Conductance is
temperature
dependent and also is inuenced by the temperature dierence. It
was necessary to test the strap at dierent stabilized temperatures
using thedierence of the two ends of the strap as the normalizing
factor, then applying a heat load to the bottom to create a larger
temperature dierence
and taking the measurement after stabilization of temperature
occurred again.
Test Setup
Mars Atmospheric Trace Molecule Occultation Spectrometer
(MATMOS):
Project Components
The purpose of this test is to determine if the empirical
results match the calculated results of a passive cooler designed
for MATMOS. By using amulti stage passive cooler that radiates to
cold space, the change in temperature between any two sides of a
stage limited to maximize conduc-
tance, this is a state of the art cooler that needs no external
power. The polished surfaces are to reect the heat from the planet
and the higheredge is extra insurance that the sun never shines
directly on the cooling manifold if there is a wobble in the orbit
of the satellite.
I modeled the exible straps and their connectors and modied the
cold head attachment above. Also interfaced with six Lakeshore
devices of fourto eight channels reading silicon diodes placed
strategically throughout the test system , sixty channels from an
Agilent reading thermocouple
temperatures and voltages across the heaters and shunt
resistors. Using these I programed the data writing virtual
instrument to calculate thepowers and the current for eight heater
circuits. This LabVIEW project was my focus for a LabVIEW course
that culminated in me passing the
Certied LabVIEW associate developers (CLAD) exam o ered on
lab.
Sounding Oceanographic Lagrangian Observer Thermal RECharging
(SOLO TREC):
The Solo Trec completed a successful year and half o the coast
of Hawaii of continuous dives measuring the salinity down to 500m
of the oceanthen transmitting the data on each resur face three
times a day. This generation will utilize wing-like structures to
direct the dives covering more
area and providing a much higher resolution study of the oceans
salinity than the current thirty thousand probes being utilized for
this function.With an improved power generation subsystem t his
generation should prove extremely eective. It uses phase changing
materials (PCM)
formulated for various freezing points down to the four degrees
Celsius found at ve hundred meter depths. The freezing and melting
of thematerials pushes on a exible membrane, in return pushing
hydraulic uid through a one way valve into an accumulator. The
accumulator consists
of a contained piston with nitrogen on one side and the
hydraulic uid on the other. The hydraulic uid compresses the
nitrogen up to 3000psi,
when the vehicle needs power it releases some of the built up
pressurized hydraulic uid to drive a generator, the hydraulic uid
then travels intoan unpressurized reservoir waiting to be pulled
into the PCM tube to start the cycle again.
An increase in eciency for this generation comes from the use of
open cell aluminum foam cylinders touching the outer walls of the
vehicle. Byboring a hole through the center and placing the
membrane containing the PCM in the center, there is a better heat
transfer from the ocean to the
PCM. Being the PCM only changes volume by 10% its increase
pushes into the open cells of the foam further increasing the area
of contact for heattransfer and displacing the hydraulic uid. One
issue with this well t hought out system is the leak of nitrogen in
the accumulator across the piston
into the hydraulic uid over time. The nitrogen being
compressible would decrease the eciency of the whole system. To
determine the impactthis phenomena may have, a power generation
subsystem was built using a pump instead of the PCM to build up
pressure. By running this
through thousands of repetitions we can measure the amount of
nitrogen that leaks into the hydraulic uid.
Testing Rig
My part was to maintain the testing system and to install the
motor and pump to simulate the PCMs. To make this work properly,
the right pump
and motor needed to be used. The rst two pumps blew o rings and
leaked, the next motor was not strong enough to get up to the
pressuresneeded. The third pump used a dierent viscosity of
hydraulic uid meaning the system needed to be drained, cleaned and
relled with a
homogeneous viscosity of hydraulic uid, in case the viscosity
played a part in the nitrogen leak rate. The working system is at
the momentrunning well thanks to the hard work of all involved. The
nitrogen leak appears to be minimal.
Acknowledgements:
I would like to thank Jose Rodrigues for his direction and
expertise. Dean Johnson for his ever smiling demeanor and coee
brewing. Jack Johnsonfor his enthusiasm and fantastic projects.
Scott Leland for his help and wealth of information and stories.
Russ Sugimura for his camaraderie and
technical writing help. Howard Tseng and Jason Kempenaar for
their friendship and in depth knowledge of the thermal world.
ArthurNa-Nakornpanom for his stories and insights on OCO2, Dr.
Helen Boussalis for the opportunities and support that has opened
so many doors for
me. Jenny Tieu for her belief and dedication in nding me a
mentor. My family for their enthusiasm and supporting me through
all the ext ra hours.
And a special thanks to my mentor Eugenio (Keno) Urquiza for his
guidance and personal tutelage, may his new endeavor be extremely
successful.Also to the Space Grant and everyone involved in the
NASA URC program, especially those at Space Center who have helped
guide and push myknowledge and research skills.
0
0.002
0.004
0.006
0.008
0.01
0.012
0.014
1 45 1 50 1 55 1 60 1 65 1 70 1 75 1 80 1 85
Conductance(W/K)
ColdEndTemperature (K)
Conductance W/K
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
1 45 1 50 1 55 1 60 1 65 1 70 1 75 1 80 1 85
AppliedHeatWarmEn
d(W)
ColdEndTemperature (K)
Watts
Experience:
Flora:
Fauna:
Thermal and Cryogenic Testing Systems Development
SPACE Center; NASA-URC
Kalind Carpenter
Graduate Student in Mechanical Engineering
California State University, Los Angeles
Jet Propulsion Laboratory
Program: Minority Student Programs; Education Office
JPL Mentors:Eugenio Urquiza
This work is supported by the NASA University Research Center
(URC) Grant No. URC NCC NNX08BA44A in
collaboration with Jet Propulsion Laboratory. Special thanks to
our SPACE Center Director, Dr. Helen Boussalis.
Heat Leak:
Temp (K) Watts
150 1.483956593
160 1.437933664
170 1.565345354
180 1.200082555
http://instrumentsystems.jpl.nasa.gov/projects/matmos/
http://www.greencleaningideas.com/2010/05/nasas-solo-trec-robotic-diver-gets-powered-by-changing-ocean-temperatures/
