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Patent 2111831 Summary

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(12) Patent Application: (11) CA 2111831
(54) English Title: IMPROVED COOLING MEDIUM FOR USE IN A THERMAL ENERGY STORAGE SYSTEM
(54) French Title: AGENT DE REFROIDISSEMENT AMELIORE POUR SYSTEME DE STOCKAGE D'ENERGIE THERMIQUE
Status: Dead
Bibliographic Data
(51) International Patent Classification (IPC):
  • C09K 5/06 (2006.01)
  • C09K 5/04 (2006.01)
  • F25D 3/00 (2006.01)
(72) Inventors :
  • WILSON, DAVID PAUL (United States of America)
  • THOMAS, RAYMOND HILTON PERCIVAL (United States of America)
  • LI, CHIEN CHI (United States of America)
(73) Owners :
  • ALLIEDSIGNAL INC. (United States of America)
(71) Applicants :
(74) Agent: GOWLING LAFLEUR HENDERSON LLP
(74) Associate agent:
(45) Issued:
(86) PCT Filing Date: 1992-06-24
(87) Open to Public Inspection: 1993-01-07
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/US1992/005368
(87) International Publication Number: WO1993/000412
(85) National Entry: 1993-12-17

(30) Application Priority Data:
Application No. Country/Territory Date
07/722,428 United States of America 1991-06-27
07/899,722 United States of America 1992-06-23

Abstracts

English Abstract

2111831 9300412 PCTABS00019
The present invention provides a cooling medium for use in a
thermal energy storage system comprising water, a guest molecule and
a surfactant having a critical micelle concentration in an amount
less than about twice said critical micelle concentration.
Preferably the critical micelle concentration is less than about
1x10-3M and more preferably between 1x10-4M and 1x10-6M. A
thermal energy storage unit which uses said cooling medium and a
process for using said thermal energy storage unit are also disclosed.


Claims

Note: Claims are shown in the official language in which they were submitted.



-9-
I CLAIM:

1. A thermal energy storage system having a crystallizer
compartment containing a clathrate forming cooling medium, a means
for circulating the cooling medium through a heat exchanger and a
means for lowering the temperature in said crystallizer
compartment; the improvement comprising:
using as said clathrate forming cooling medium a mixture
comprising water, a guest molecule and a surfactant in an amount
which is less than about twice the upper value of said
surfactant's critical micelle concentration range; wherein said
amount is about 200 ppm or less.

2. The thermal energy storage system of claim 1 wherein
said surfactant is used in an amount up to about said
surfactant's critical micelle concentration.

3. The thermal energy storage system of claim 1 wherein
said critical micelle concentration is between about 1x10-4M and
about 1x10-8M.

4. The thermal energy storage system of claim 1 or 3
wherein said guest molecule is selected from the group consisting
of hydrochlorofluorocarbons and hydrofluorcarbons.

5. The thermal energy storage system of claim 1 or 3
wherein said guest molesule is a hydrochlorofluorocarbon s?
from the group consisting of 1,1-dichloro-1-flurorethan?
chlorod1fluoromethane.

6. The thermal energy storage system of c?
wherein the surfactant is alkyl dimethyl benz?
octaphenyl phosphoric acid.

7. The thermal energy storage system ?
wherein the amount of said surfactant used is le?
ppm.


-10-
8. A process for thermal energy storage wherein a cing
medium is induced to form a clathrate, and heat is removed from
the surroundings to melt the clathrate; the improvement
comprising:
using as said cooling medium a mixture comprising water; a
guest molecule and a surfactant having a critical micelle
concentration less than about 1x10-3M in an amount less than twice
the upper value of said critical micelle concentration range;
wherein said amount is about 200 ppm or less.

9. The process of claim 8 wherein said surfactant has a
critical micelle concentration between about 1x10-4M and about 1x10
8M.

10. The process of claim 9 wherein said surfactant is alkyl
dimethyl benzyl ammonium salt of octaphenyl phosphoric acid.

11. The process of claim 18 wherein the amount of said
surfactant used is less than 200 ppm.

12. A cooling medium for use in a thermal energy storage
system comprising water, a guest molecule and a surfactant having
a critical micelle concentration in an amount is less than about
twice the upper value said critical micelle concentration range;
wherein said amount is about 200 ppm or less.

13. The cooling medium of claim 22 wherein said critical
micelle concentration is less than about 1x10-3M.

14. The cooling medium of claim 23 wherein said critical
micelle concentration is between about 1x10-4M and about 1x10-?M.
.

15. The cooling medium of claim 24 wherein the surfactant
is alkyl dimethyl benzyl ammonium salt of octaphenyl phosphoric
acid.


-11-
I CLAIM:

16. A thermal energy storage system having a crystallizer
compartment containing a clathrate forming cooling medium, a means for
circulating the cooling medium through a heat exchanger and a means for
lowering the temperature in said crystallizer compartment; the improvement
comprising:
using as said clathrate-forming cooling medium a mixture comprising
water, a guest molecule and a surfactant having a critical micelle
concentration and the amount of surfactant is less than twice the upper
values of the surfactant's critical micelle concentration range; wherein
the surfactant is not Zonyl FSN.

17. The thermal storage system of claim 16 wherein the critical
micelle concentration of the surfactant is less than the lower value of the
critical micelle concentration of Zonyl FSN.

18. The thermal energy storage system of claim 16 wherein said
surfactant's critical micelle concentration is less than about 10-3M.

19. The thermal energy storage system of claim 16 wherein said
critical micelle concentration is between about 1x10-4M and about 1x10-8M.

20. A process for thermal energy storage wherein a cooling medium is
induced to form a clathrate, and heat is removed from the surroundings to
melt the clathrate; the improvement comprising:
using as said cooling medium a mixture comprising water, a guest
molecule and a surfactant having a critical micelle concentration less than
about 1x10-3M in an amount less than twice the upper value of said critical
micelle concentration range.

21. The process of claim 20 wherein said surfactant has a critical
micelle concentration between about 1x10-4M and about 1x10-?M.

22. A cooling medium for use in a thermal energy storage system
comprising water, a guest molecule and a surfactant having a critical
micelle concentration range with an upper limit of less than 1x10-3M and
present in an amount is less than about twice said critical micelle
concentration range.

Description

Note: Descriptions are shown in the official language in which they were submitted.


WO93/~4t2 2 ~ 31 PCI~/US!~2/0!;368

.

I~RO~:D COOLIN~ P~EI)IlJM FOR IJ8~ l A
.,
T~R~ ENERGY 8TORAG~ ~Y8?EM
~ This application is a continuatisn-in-part of
`,5 Application Serial No. 722,428, filed on June 27, 1992.

. B~ck~Qun~ Q~_~h~ Invent on
Thermal energy storage 5ystems contain a`cooling
~ medium, which is frozen during the off peak, evening
r hours. During ~he daytime, heat from the s~rrounding
.~ 1~ area is us~d to ~elt the cooling mediu~. The ramoval
of heat to drive the decomposition causes the
surrounding ar~a to b~come cool~r.
U.S. Patent No. 4,540,501 discloses a the ~ al
energy stor~ge system which u~es clathrates as the
cooling ~ediu~. Clathrates are hydrates which use a
non-sto~chio~etric number o~ uater molecules per guest
molecule. Th~ guest moleculQ f~lls th~ interior of the
lattice, stabilizing the clathrat~. This stabilization
allows the watex lattic~ ~ructure to form at
te~peratures si~nificantly higher than the temperature
of ice fo~mation (0C). The ~uest ~ol~cul~ must be
highly insoluble in water, and must have a molecular
~ize which is 1~8 than 7 ~.
The halogenated hydrocarbons which are used as ~he
gue~t ~ol~cul~ are not water ~i~cible. Clathrates
will not for~ unle~s the guest ~nd ~os~ (lat~ice)
co~psund3 ~r~ in contact. In an ~ttempt to bri~g the
gUB~t mol~cul~ and wat~r into closer contact, v~rious
~ur~n~tant~ bava been add~d. U.S. Patent No. 4,540,501
di~close~ using a nonionic ~luoro~ur~actant having the
chemical ~onmula F(CF2CF2) ~-~CH2cH20 (CH2~H20) 0~ when the
gue3t molecule i~ a refrigerant cho~en fro~ brominated,
chlorinated ~n~ ~luorinated hydrocarbsns including
CCl2F2, CCl3P, CBr~3, CHClzF~ CHClF2, CH~ClF and CH3CClF2.
U.S. Patent No. 4,821,79~ disclo~es the ~SR Or Zonyl~
Plsrosur~actants in amounts between 1 to 5000 ppm
gener lly, and th~ use o~ Zonyl FSN with

~ W~93/ ~ 12 PCT/US92/0~
...
3 1

trichlorofluoromethane in the ~mount of about 200 to
300 ppm. Zonyl9 Fluorosurfactant and Unidyne DS-401
have been added to water-l,l,l-tetrafluoro~thane
clathrate forming thermal energy storage medium in
- 5 Foxma~ion of Gas Hydrate or I~e ~y ~i~ect-Contact
Eva~ora~ion of CFC Alternatives, F. Isobe and Y.H.
Mori, Int. J. Re~rig., vol. 15, No. 3 (1992~, pgs.
137 - 142. Proc. Inter. SQC. Ener~y Convers. ~nq.
.~ Con~!, Akiya et al., 1991, 26th~6) 115-119 used two
unspecifie~ surfactants in concentrations up to 500 ppm
to enhance the rate of formation of the clathrate from
a water ~ dichloro-1-fluoro~thane cooling medium.
., How~v~r, for the known guQst molecules
relativ~ly l~rge quantities of ~ur~actant have been
u~Qd (up ts and in eXcQss of 1000 ppm) and so~e of the
guest ~olecule will a~sociat~ with the urfaetant
inst2ad o~ forming a clathrat~ wlth ~atex. This
decr~as~ khe ef~iciency of ~ha th~rmal en~rgy storage
system.
~rior to the present inv~nti~n ther~ has been no
teaching in the art of how to sQlect a surfactant for a
particular cooling medium or how to determine the
amsunt of ~urf~ctant which will in~urQ opti~u~ mixing
~ with a mlni~u~ of gue~t molecul~ a~ oci~tion.
t~ , 25 Furth~rmore, many of th9 guest mol~cul~ presently
b~ing u~d ~re CFC ~uch as trichloro~luoromethane
(CYC-ll). Th~ use o~ the~ eo~pound~ i~ beeoming
di ~avor~d b¢eau~e o~ the detr~m~ntal ef~eet to the
ozone layor. Thu~ it i9 a goal o~ th~ pre~ent
invention to ~ind a ~oolng mediu~ wh~eh pO3~5 less of
a thr~at to th~ ozone }ayer. Halohydroearbons such as
HCFC-141~b) whieh eontain hydrog~n, and are believed to
po8e le3s o~ ~ threat to the ozon~ layer, and are thus
propo ed a8 ~he guest ~olecule in elathra~e formation
aeeording to the present invention.


~,,

".

~ WO93/~Y2 PCT/~S92/~
2 ~ 3 ~
..,.


Descrip~i~n_Qf the Fi~u~e
FIGURE 1 shows the relationship between the
surfa~tant concentration and the sur~ace tension of
, wat~r for the surfactant D~SC~.
- 5 Figure 2 shows the relation~hip between surfactant
concentra~ion (DRSC~) and the interfacisl tension for
l,l-dichlo~o-~-fluoroethane/wat~r 801ution.

- Detailed D~s~iDtion of the nv~ntion
.
` ~The pre nt invention pro~des a cooling medium
for ug2 in a ~her~al en~rgy tor~ge system comprising
wat~r, a gu~t ~olecule ~nd a ~urfactant having a
critical micelle concentration in an ~ount les~ than
about ~wic~ th~ cr~tical micell~ concentration.
Pr~ferably ~h~ eriti~al ~icell~ conc~ntration i less
than about lxlO'~ and mor~ pre~r~bly b~ween lx10-4M
and lxlO'q~. A thermal energy ~tor~ge uni~ which uses
the cooling ~diu~ and a proG~s ~or u~ing the thermal
; energy storag~ unit ara also di~clo~ed.
The gu~st ~olecules Or ~he present in~ention may be any
compound capabl~ o~ forming a cl~thra~ with ~ter.
Suitabl~ gues~ moleculas g~nerally hav~ an average
diameter o~ le~s than about 7 A. Pr~f~rably, ~he guest
molQcul~ re~rigerant salQctQd fro~ the group
consistin~ o~ hydrochlorofluorocarbon~,
hydro~luorocarbon~, and mixtur~3 th~reo~. Exa~ples of
pr~orr~d ~ydrochloro~luorocarbon gu~3t molecules
includs l-~luoro-1,1-dichloro~thane, 2nd
chlsrodi~luoromethane. Exa~plQs o~ prQ~erred
hydro~luorocarbon gue3t mol~cul~ include ~,1,1,2-
tetra~luoroethane, 1,1,l-tri luoro~than~,
di~luororm~th~ne, p~ntaflusro~thane, ~nd 1,?-
dl~luoro~thana. ~he con~iguration o~ th~ th~r~al
~n~rgy storag~ gy~t~ o~ thB pr~s~nt inv~ntion is the
similar to ~hat o~ U.S. patsn~ No. 4,540,501.

~ W0~3/~X P~T/~2~
.....
~ ~lii3~1

~ . 4
;~ To form a clathrate the guest molecule and water
must be dissimilar and be in contact with each other.
~` the more intimate the contact, the more efficient the
clathrate formation will be. Accordingly, emulsions of
water and the guest molecule are highly desirable~
Cla~hra~es of the pre3ent in~en~ion ~re formed from the
guest molecule, and water. Depending on the size of
the guest molecule between 5 to 17 water molecules per
-1 guest molecule are needed to ~orm a clathrate.
Preferably the amount of sach the guest molecùle and
water is at 12ast equal to the ratio necessary to form
clathrate. ~ore pr~farably, an 8XC~SS of water is used
to ~aintain a -~lurry, and en~ure con~inuous a~d
e~ficient h~t transfer. ~or exampl~, where HCFC-
141(b~ is u~ed, 20 moles of wat~r is used for each 1mol~ o~ HCFC-141(b).
The concentration of fre~ surfactant in water
af~ects th~ properties of th~ ~ter and particularly
the ~uxfacQ tenRion, which i shown ~or DRSC~ in Figure
1. For mu}tipha~ syst~s, such ~s th~ guest
molecule/w~ter mixtur~s which ar~ u ed in thermal
energy storage systems th~ intQr~acial tansion between
the gue3t molocule and water ~ay b~ mea~ured. The
er~ect o~ DRSC at varying concentrations on a 1,1-
, 25 d~chloro~ luoroethane/water i8 shown in Fiyure 2.
Th~ pr~psrtie~ of both solution chang~ rapidly b~tween
about 25 ppm and a~out 125 ppm. B~yond that rang~ of
conc~ntration, propQr~ies changa ~ora gradually. This
narrow concentratîon range in which prop2rtie~ change
rapidly is c~lled th~ critical ~icells concentration or
cmc. A~t~r the cmc has be~n Qxc~Qd~d w~ter surface
tension dQcreasQ only ~lightly by adding more
sur~actant~ Because water-guest moleculs mixing
increas~3 a3 the ~urf ace tension o~ water decreases,
maximum water-guest molecule mixing i8 achiev~d n~ar

:`'~ `i
;~: .l,
.` 1 WO 93/00~1~ Prr/u~g2/o53~i8
3 ~
''`,
,

the cmc. Moreover, after about 200 ppm (twice the cmc~
~-i of the DRSC9 surfactant has been added there is
virtually no change in ei~her the surface or
~: interfacial tension. Thus, regar~less of what
. 5 surfactant i5 used, the optimum concentra~ion of
surfactant necessary ~o provide maximum ~ixing is not
gxeater th~n about twice ~ha critical micslle
concentra~ion, preferably l~ss th~n about 1.5 times the
c~c and most prefer~bly le~s th~n about the cmc. By
. 10 - limitin~ th~ amount of surfactant u~d to less than
, . ..
. about twice the cmc it is possible to use small amounts~s o~ surfactants, e~pecially if the critical micelle
. concentration is s~all (les~ ~h~n abou~ 10-3M).
Each ~ur~actant ha~ a uniqu~ cm~, whi~h depends
upon its ~tru~turQ. G~nQrally ~urfactants ~ith longer
. hydrocarbon chains havs lower critic~l micell~
conc~n~ration~. The low~r th~ c~c, the 1~ surfactant
i~ neeassary to achi~ve ~axi~um mixing. Thu~,
pr~f~rably surfactants of ~h~ pr~l~nt invention have
critical mic~ concsntrations w~ich ~r~ be}ow lxlO-
~M, and pr2ferab1y..b4tw~n ~xlO-~ and.lxlO~~M. Critical
:~ micelle conc~ntrations ~or many ~urf~ctants are listed
; in "cr~tical Mic~lls Concentrations o ~queous
Suxf~ctant Syste~ by MuX~r~ and My3~1~ [NAt. Stand.
R~f. D~ta S~r., Nat. Bur. ~tand. (U.S) 36, Feb. 1971.
Many way~ o~ d~t~rmining th~ c~c o~ 3urfactant~ are
; d~cribed by Mukerje~ et al. ~oraover, b~c use the
. pres~nt invent$on providQ~ a l~rg~ number o~ ~uitable
surf~ct~nt3, surfaet~ntQ which produc~ only gradual
~ 30 chang~s in sur~ac~ or inter~acial tension ov~x varying
.~ sur~actan~ concentratisn3, ~nd thu~ ha~e poorly definedCmC-Q are no~ preferred. An example o~ a surfactan~
having a poorly de~ined c~c is Zonyl~ FSN.
Mos~ prs~erably, a ~urfactant having a cmc less
than lxlO-qM is u~ed in an amount about equal to or

~,4,

:`g
~ W093/~12 PCT/~S92/05

8 ~ ~


slightly in excess of the cmc. By choosing surfactants
ha~ing low ~mcs and limiting the amount of surfactant
to the c~c, inefficiencies du2 to gu~st molec~le
association with the aggregated surfactant and
S competition b~tween th~ surfactan~ and guest molecule
~ay be mini~iz~d. ~hen any non-polar substance is in
contact with water, the wat~r ~o}~cules beco~e arranged
or organiz~d in a clu~tçr around ~he non-polar ~oi~ty.
It is belieYed that clathrates are formed by th~
crystallization of this clust~r. Si~ilarly, ~hen a
~urfactant is pr@sent, water ~olecules clus~er around
the sur~actant, forming surfactant aggr~gat~s. This
co~petition between the potential guest molecules and
surfacta~t molQcules for wat~r ~olacul~s d~crea es the
amount of cl~hrat~ which can ~ for~ad with a given
: amount o~ w~ter ~olecule~. ThUB ~t iS pr~ferable t~
~ini~izs the a~o~t o~ ~ur~ac~nt u~d.
In ~o~ ~ituation8, it ~ny b~ de~irabla to exc~ed
the c~c in order ~o acheiva ~ particul~r ~f~ct. When
the cmc is ~ow, the concentration of sur~actant may
~till be qui*e low ~s co~pared to convention~l
sur~ctant conc~ntration even though it is above the
cmc. Thus, thQ competition b2~w~en the sur~actant and
tha gu~t mol~cule is proportionataly l~s~ ~ev~re, even
: , 25 nt conc~ntr~tions ~hich are ~bov~ th~ cmc. Thus,
aur~ctant~ with cr$tical mic~ concentrations below
~bout lXlO'k ar~ prefe~ed.
An Qx~ple o~ a surf actant species uhic:h has been
~ound partic~larly e~fecti~a ~n ~nhancing emul~ion
formation where HCFC-141(b) is u~ed as t~ guest
molecule i~ surfactant DRSC (alkyl dimethyl benzyl
ammonium salt Or oc~aphenyl pho~phoric acid ~
commQrcially aYailabl~ fro~ Allied-Signal, Inc.). The
physical propQrtie~ of DRSCo ar~ 8hOWrl in Table 1,
3 5 below.

~' W~ ~3/00412 PCrlUS92/~36
., 2~ 31
.. ..
.

Table 1
I .; _ -- - . _ _.
Surf actant BP Specif ic Vapor Sol O in H20
.j~ ( F) Gravity Press . at 2 5 C
. . ~ 2 5 - C mm Hgê 2 5 - C
DRSC~ 180~ 0 ~ 95 <1 Sol .
~ o ~ Hg ~ - , . .
The cmc for DRSC~ is between about 50 ppm and
about 125 ppm, which was determined by measuring the
sur~ace tension of water as increa~ing amounts o~ DRSC~
were added! Thus, less than a~out 200 pp~ of the DRSC~
is raquired to insure emulsion formation between water
and ~he chosen guest molecul~. Prefer~bly less than
100 ppla DRSC 19 is used. The losses of the gu~st
ms~lecule (HC:P'C 141(b)) due to as. ociation with the
sur~ ac~ant d~ ::rea-ce as the aDlount of suriEactant us d is
..
dec~!aas~d~ ther~by incraasing t~ ~f~ici~ncy o~
clathrate formation, and ~ ther~al energy storage
system.
Agitation is not required ts ensure clathrate
formation of th~ cooling mediu~ o~ the ~resent
invention. However, agitation may be used to further
2 0 encourag~ clathrate or~ation ~
Emul~ion~ f or~ed ~ccording to the present
inYention ~r~ 3tabl~ at roo~a t~mp~rature, and remain
eDIul~ d ~or as long 213 two d~ys ~ith mini~um
lnag~. Th~ clathrat0 is form~d in a ~ rage
tank/crystall~z~r. The pr~sure in the c:~stallizer i5
decre~d by me~ns of a co~pre~sor, ~ described in
moxe d~tail in U.S. Patent No. 4,5~0,501, and heat is
removed unt~l the temperature o~ ~ormation f or the
clathratg is reach~d. The prsssure ~nd te~perature are
3 0 maintained until ~11 sf t~e clathrate i5 f ormed . The
clathrate is circulated through the heat exchanger via
the recirculatisn loop. Clathrate i5 circulated
through the heat exchanger, decompos~d, and the water

WQg3~12 PCT~US92/~5

`-;
~ 3 ~ 8

and guest molecule mixture is returned to the
crystallizer.

Example
. 5A solu~ion of DRSC~ ha~ing a concentration of 25
ppm was ~ade by adding 0.025 ml of DRSC~ to 1 li~er of
w~ter~ 300 ml o~ the surfactant solution was poured
into a 500 ml jar, and 30 ml of 141(b) was added. The
jar was capped and shaXen vigorously ~or 1 minute. An
emulsion f~r~ed in the jar, which W~5 stable and
r~main~d emulsi~ied for two days without noticeable
drainage.
The se led jar was placed in a fr~ezer at 40F. A
considerablQ amount of snow~lak~-like cryst~ls (the
~5 ~lathrat~) wa3 observsd in the ~ar a~ter 1.0 hour. The
jar was lef~ in the ~r~ezQr overnight. By morning
cry~tal$ had ~or~d in ~he ~ar, indicating that
cla~hrate had ~orm~d.
,Accordingly, DRSCo, which h~ a lo~ emc, is a
suitabl~ aid for clatbrat~ formation, for~ing clath-;ate
.~ at low surfactant concentration~. Becau~ only a small
amount of sur~actant i5 required (tWiCQ the cmc or
1~8s ), thers i~ less surfactant to as~ociate with the
guQst molecule (here HCFC-141(b)), and thu~ the
clathrat~ ~ormation proc~ss, and the ther~al en~rqy
storag~ syst~m are mor~ e~ici~nt.

Representative Drawing

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Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date Unavailable
(86) PCT Filing Date 1992-06-24
(87) PCT Publication Date 1993-01-07
(85) National Entry 1993-12-17
Dead Application 1997-06-24

Abandonment History

Abandonment Date Reason Reinstatement Date
1996-06-24 FAILURE TO PAY APPLICATION MAINTENANCE FEE

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $0.00 1993-12-17
Maintenance Fee - Application - New Act 2 1994-06-24 $100.00 1993-12-17
Registration of a document - section 124 $0.00 1994-06-28
Registration of a document - section 124 $0.00 1994-06-28
Maintenance Fee - Application - New Act 3 1995-06-26 $100.00 1995-03-24
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
ALLIEDSIGNAL INC.
Past Owners on Record
LI, CHIEN CHI
THOMAS, RAYMOND HILTON PERCIVAL
WILSON, DAVID PAUL
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Drawings 1993-01-07 1 26
Claims 1993-01-07 3 148
Abstract 1993-01-07 1 63
Cover Page 1993-01-07 1 25
Description 1993-01-07 8 573
International Preliminary Examination Report 1993-12-17 11 299
Fees 1995-03-24 2 412
Fees 1993-12-17 1 113