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1
Development of CryoTel® DT Cryocooler
S. Kim1, E. Holliday1, R. Unger2, R Wiseman2
1Sunpower Inc., Athens, OH 45701 2 Consultants
ABSTRACT
A small split-type Stirling cryocooler, CryoTel® DT, has been developed for small and portable systems, where small size, light weight and low vibration signature become important. The split cold head equipped with a small passive balancer is coupled to a dual-opposed pressure wave generator in which two opposing twin pistons cancel the vibration of each other. The heat lift measured in the lab tests was 2.3 W at 77 K with 30 We of input power and 2.7 W at 77 K with 40 We, and the COP achieved a new record, 15% higher than that of the previous best efficiency CryoTel® CT. Three hermetically-sealed DT cryocoolers were built and tested in a certain customer’s facility for the qualification. The test results confirmed that the DT cryocoolers were qualified by exceeding the performance specifications and satisfying all of the other requirements. The vibration acceleration of the cold head was also measured at less than 40 mG. This paper presents the features and the performance test data of the new cryocooler.
INTRODUCTION
The CryoTel® DT is a small split-type Stirling cryocooler driven by a dual-opposed pressure wave generator that is a new addition to Sunpower’s commercial product line-up. The current CryoTel® models: the MT, CT, and GT are integral-type Stirling cryocoolers provide high performance, low cost and long life operation1,2. The CryoTel® family of cryocoolers, based on Sunpower’s innovative technologies of free piston, linear motor, and non-contact gas bearing, offers unique solutions to various applications in the market and builds a solid reputation for unrivaled performance and quality.
The new cryocooler DT is an extension of the CryoTel® family that is designed to satisfy the following major requirements as requested by a specific customer: cooling capacity (heat lift, greater than 1.5 W at 77 K), light weight (total mass, lighter than 1.5 kg), small size (outside diameter, less than 3”), and low vibration. As shown in Figure 1, a split configuration along with a dual-opposed pressure wave generator was chosen for the inherent reduction of the vibration signature. The remaining vibration of the cold head is attenuated by a small passive balancer. Subsequently, another application for higher cooling power was added by the customer, which eventually resulted in two different CryoTel® DT cryocoolers, the DT55 and the DT60.
Sunpower launched the development program in 2011 and shipped three hermetically-sealed DT cryocoolers to a customer for the qualification test in early 2012. All of them passed the test and exceeded the requirements. The hermetically-sealed CryoTel® DT55 consists of a cold head
101Cryocoolers 17, edited by S.D. Miller and R.G. Ross, Jr.©¶International Cryocooler Conference, Inc., Boulder, CO, 2012
of 39mm respectivgeneratorqualificatgeneratorfor the DF
DESIGN
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N FEATUR
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d to overcomn/displacer cylinder unc
bore size dof thermal
nt reduction, it is difficio as the bstrength. T
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ificant effogies newly CryoTel® mwas minimbe was madimized withe is also bnce is far gr
Figure 1. He
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RES
DT cryocoont cryocoolMT, since th
the MT. Sme the genebore size d
changed, thedecreases ml conductio
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bore size reTherefore fu
ons3 were port was put
developed manufacturi
mized by higde out of a h respect to being tried reater than t
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mm in lengths 1.2 kg; tically-sealed
same coldr; its total mfacturing).
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he DT was ubsequently
eral tendencdecreases me area of le
maintainingon to the be size coulduce the sizeeduction, beurther impr
erformed winto the mfor the pering processgh-precisionTi alloy, a machiningin the DFMthe requirem
sealed CryoT
h, and a presthe cold hed DT60, wd head as D
mass is 1.3 k
signed bases. The initaimed for ay, some keycy that the smaintainingeakage flowthe wall th
bore size ind become su
of the cleaecause of throvements o
with the newmanagementrformance is. The clearn machininglow conduc
g capability M processments.
Tel® DT55 a
ssure wave ead weighs which is bDT55 but akg. Further
ed upon the tial design a much smay componensmaller the the clearan
w to the boreickness of tncreases. T
ubstantial enarance as whe limitatioof the desi
w configuratt of leakagimprovemenrance betweg, coating, ction materand materiadespite co
and Controlle
generator o0.2 kg and
being builta slightly loptimizatio
Sunpower began wi
aller and lignts and critisize, the low
nce betweene size increthe cold fin
Thus, the tonough to impwell as the won of machgn are requ
tion for the ge and condnt as well aeen the pistand aligninial, and its al strength. nduction lo
er
of 55mm and the presst for the ularger presson is now in
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hining capabuired to pr
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nd 127mm sure wave upcoming sure wave n progress
chnologies aled-down ooler than ions were iciency. If
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ness at the bility and revent the
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The cold thickness
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2 102 MEDIUM-CAPACITY 50-80 K SINGLE-STAGE CRYOCOOLERS
PB
CT
Passive Balancer
Connecting Tube
Cold He
PressureWave Generat
ad
e
tor Controller
r
CONTRO
The 30mm incCT, GT, The majocomponena quad flaproviding and RS-2cold end power can
CONFIG
The wave genpressure wsingle coconfiguraconnectinthe wavepiston asscontributithe cold hexisting C
Anothead and show twoconnectinwhole unthe heat l
Figu
OLLER
controller fcluding the and MT of or differennts in small
at pack (QFPclosed loop
232 communtemperaturen be modul
GURATION
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o different eng tube versnit to fit intoift down by
ure 2. Cryo
for CryoTelenclosure. the CryoTe
nces lay in ler packagesP). Like the p temperaturenications ine, near sinuated over a
N
DT is a sphich is widerator vibratin space anich the coldeps the cold The displahe pressure
nuated with ured in the ccryocoolers.age of the sre wave genexamples: tsus the in-lo a cylindri
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oTel® DT5
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cold head wnear sinusoisive balanceless than 40
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Figure 1, 82nd generat
rcuitry and er componeball grid arrly of cryocodiode with a g control varange of po
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which is midal motioner. The vibr0 mG, whic
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0 mm long c
84.5mm × 6tion controlsoftware is
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oolers, it is D stability of
ariables suchwer control
ual-opposedr low vibrasing pistons
addition, ugh a smalland the harm
much lightern, and so itsration accelh is only 20
rrangement.tions. Figurnt with 100ng tube alloever the lat
connecting
63.5mm × ler for the identical.
he use of instead of
DSP-based f +/- 0.1 K, h as target l. Cooling
d pressure ation. The
sharing a the split
l diameter monics of r than the vibration eration of 0% of the
The cold re 2 and 3 0mm long owing the tter brings
tube
3 103THE DEVELOPMENT OF CRYOTEL® DT CRYOCOOLER
Fig
PERFOR
The ranging frdesigned CryoTel®optimizedvarious pelong and power, an
The side of Fiload tempCarnot, athe CT. TDT55 remThe inputinput pow
The Ddown to 3of the DTas it is de
gure 3. Cryo
RMANCE
CryoTel® from 5 to 15
for the fir® family. Ld for the Derformance two differe
nd the DT60test results igure 4 indiperature reaachieves 23%The performmains incomt power req
wer is over 3DT60 lifts 232.1 K as shT55, but theesigned for.
oTel® DT5
TEST RES
cryocooler5 W at 77K.rst model, tikewise, the
DT55, even tests were p
ent sizes of p0 up to 40 Wof each of
icates that thaches down % at 77 K, mance mapmparable ov
quired to lift3 W. 2.7 W at 77hown in figu performancThe heat lif
Figure
5 in in-line
SULTS
rs, MT, CT All membethe CT, hoe DT55 andthough the
performed inpressure wa
We. f the DT cryhe DT55 lifto 32.4 K. which is 1
p curves at ver the widt 1 W at 77
7K with 40 ure 5. The ece map curvft at 90K wi
e 4. CryoTel®
arrangemen
T, and GT ers have the
olding the pd the DT60e DT60 wan the lab usiave generato
yocoolers afts 2.3 W at The percen5 % higherthe right-h
de range of K is only 1
We input pefficiency cves confirmith 40 We in
® DT55 perf
nt with 150
offer differe same-sizeplace of thecryocooler
s designed ing a cold heors; the DT
are shown in77 K with
ntage of ther than that o
hand side cof input pow15 We, and
power, and turve of the
m that the DTnput power
formance Te
mm long c
rent coolingcold head, e best efficrs have the
for higher ead, a conne55 accepts
n Figure 4 30 We inpuCOP to Caof the previonfirm thaters and opethe heat lift
the no-loadDT60 is sli
T60 offers hr is over 3.5
est Data
connecting t
g power cawhich was ciency cryosame-size ccooling po
ecting tube oup to 30 W
and 5. The ut power, anarnot efficieious best crt the perforerating tem
ft at 90 K wi
d temperaturightly lowerhigher cooliW.
tube
apabilities originally
ocooler of cold head, ower. The of 100mm
We of input
left-hand nd the no-
ency, % of ryocooler, rmance of
mperatures. ith 30 We
re reaches r than that ing power,
4 104 MEDIUM-CAPACITY 50-80 K SINGLE-STAGE CRYOCOOLERS
CONCLU
Sunpcryocoolewas dramunits havavailable
REFERE 1. Unge
Engin 2. Unge
51, A 3. Gide
Asso
USION
power has er driven bymatically love passed th
in 2013.
ENCES er, R., Keiterneering, Voler, R., “The Amer. Institueon, D., SAGociates, Athen
Figure
successfully a dual-op
owered whihe qualifica
r, D., “The dl. 49B, Amerdevelopment
ute of PhysicsGE User’s Gns, OH, 2011
e 5. CryoTel®
ly developpposed presile maintaination tests
developmentr. Institute oft of the Cryos, Melville, N
Guide, Stirlin1.
® DT60 Perf
ped the Crssure wave ning the unof a certain
t of the Cryof Physics, MoTelTM LT NY (2006), pg, Pulse-tub
formance Te
ryoTel® Dgenerator.
nrivaled pen customer
oTelTM famelville, NY (and GT,” Ad
pp. 1719-172be and Low-
est Data
DT, a smalThe vibrati
erformance. r and the n
mily of coole(2004), pp. 1dv. in Cryog25. T Cooler M
ll split-typeion of the c
The pre-pnew product
ers,” Adv. in 401-1404.
genic Enginee
Model Classic
e Stirling cold head
production ts will be
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ering, Vol.
cs, Gedeon
5 105THE DEVELOPMENT OF CRYOTEL® DT CRYOCOOLER