Title of Invention

"A METHOD AND APPARATUS FOR PROVIDING REFRIGERATION TO A HEAT LOAD"

Abstract A method for providing refrigeration to a heat load comprising; i) Compressing pulse tube gas (45) to produce hot compressed pulse tube gas, cooling (44) the compressed pulse tube gas, and expanding the cooled pulse tube gas to produce cold pulse tube gas; ii) Warming (42) the cold pulse tube gas by indirect heat exchange with heat transfer medium (5) to produce cooled heat transfer medium (6), and warming (30) the cooled heat transfer medium by indirect heat exchange with refrigeration fluid (13) to produce cooled refrigeration fluid (14) at a first temperature within the range of from 20 to 280K; iii) Providing refrigeration into the cooled refrigeration fluid to produce cold refrigeration fluid (17) at a second temperature lower than said first temperature and within the range of from 3 to 150K; and iv) Warming (32) the cold refrigeration fluid by passing refrigeration from the cold refrigeration fluid into a heat load.
Full Text SYSTEM FOR PROVIDING CRYOGENIC REFRIGERATION
Technical Field
This invention relates generally to low
temperature or cryogenic refrigeration and, more
particularly, to pulse tube refrigeration.
Background Art
The cooling, liquefaction and/or subcooling or
densification of certain gases such as neon, hydrogen
or helium requires the generation of very low
temperature refrigeration. For example, at atmospheric
pressure neon liquefies at 27.IK, hydrogen liquefies at
20.39K, and helium liquefies at 4.21K. The generation
of such very low temperature refrigeration is very
expensive. Inasmuch as the use of fluids such as neon,
hydrogen and helium are becoming increasingly important
in such fields as energy generation, energy
transmission, and electronics, any improvement in
systems for the liquefaction of such fluids would be
very desirable.
A recent significant advancement in the field of
generating low temperature refrigeration is the pulse
tube system wherein pulse energy is converted to
refrigeration using an oscillating gas. Such systems
can generate refrigeration to very low levels
sufficient, for example, to liquefy helium. However,
such refrigeration generated by pulse tube systems is
very costly if the starting point is a relatively high
temperature such as ambient temperature.
Accordingly, it is an object of this invention to
provide a system for providing cryogenic refrigeration
using a pulse tube system which can more efficiently
provide such refrigeration than can heretofore
available systems using pulse tube technology.
Summary Of The Invention
The above and other objects, which will become
apparent to those skilled in the art upon a reading of
this disclosure, are attained by the present invention,
one aspect of which is:
A method for providing refrigeration to a heat
load comprising:
(A) compressing pulse tube gas to produce hot
compressed pulse tube gas, cooling the compressed pulse
tube gas, and expanding the cooled pulse tube gas to
produce cold pulse tube gas;
(B) warming the cold pulse tube gas by indirect
heat exchange with heat transfer medium to produce
cooled heat transfer medium, and warming the cooled
heat transfer medium by indirect heat exchange with
refrigeration fluid to produce cooled refrigeration
fluid at a first temperature within the range of from
10 to 28OK; '
(C) providing refrigeration into the cooled
refrigeration fluid to produce cold refrigeration fluid
at a second temperature lower than said first
temperature and within the range of from 3 to 150K; and
(D) warming the cold refrigeration fluid by
passing refrigeration from the cold refrigeration fluid
into a heat load.
Another aspect of the invention is:
Apparatus for providing refrigeration to a heat
load comprising:
(A) a pulse tube refrigerator comprising a
regenerator body, a pulse tube body having a pulse tube
heat exchanger, means for generating pressurized gas
for oscillating flow within the regenerator body, and
means for expanding gas within the pulse tube body
through the pulse tube heat exchanger;
(B) a forecooling circuit comprising a
forecooling heat exchanger, means for passing heat
transfer medium from the pulse tube heat exchanger to
the forecooling heat exchanger, and means for passing
heat transfer medium from the forecooling heat
exchanger to the pulse tube heat exchanger;
(C) means for passing refrigeration fluid to the
forecooling heat exchanger, and means for providing
refrigeration into the refrigeration fluid downstream
of the forecooling heat exchanger; and
(D) a heat load and means for passing
refrigeration from the refrigeration fluid into the
heat load.
As used herein the term "indirect heat exchange"
means the bringing of fluids into heat exchange
relation without any physical contact or intermixing of
the fluids with each other.
As used herein the term "direct heat exchange"
means the transfer of refrigeration through contact of
cooling and heating entities.
As used herein the term "magnetize" means to
induce magnetic properties to a substance by use of an
externally applied electrical field.
As used herein the term "heat load" means an
entity at a higher temperature capable of receiving
refrigeration and thus being cooled to a lower
temperature.
Brief Description Of The Drawings
Figure 1 is a schematic representation of one
preferred embodiment of the invention wherein lower
level refrigeration is provided to the cooled
refrigeration fluid by operation of a multiple
component refrigerant compression/expansion cycle.
Figure 2 is a schematic representation of another
preferred embodiment of the invention wherein lower
level refrigeration is provided to the cooled
refrigeration fluid by operation of a Brayton
refrigerator.
Figure 3 is a schematic representation of another
preferred embodiment of the invention wherein lower
level refrigeration is provided to the cooled
refrigeration fluid by operation of a magnetic
refrigerator. -
Detailed Description
The invention will be described in detail with
reference to the Drawings. Referring now to Figure 1,
pulse tube refrigerator 40 comprises regenerator body
41 and pulse tube body 1 having pulse tube heat
exchanger 42. Regenerator 41 contains pulse tube gas
which may be hydrogen, neon, nitrogen, a mixture of
helium and neon, a" mixture of neon and nitrogen, or a
mixture of helium and hydrogen. Mixtures of helium and
hydrogen are preferred.
A pulse, i.e. a compressive force, is applied to
the hot end of regenerator body 41 by means of pulse
generator 43 thereby initiating the first part of the
pulse tube sequence. Preferably the pulse is provided
by a piston which compresses a reservoir of pulse tube
gas in flow communication with regenerator body 41.
Another preferred means of applying the pulse to the
regenerator is by the use of a thermoacoustic driver
which applies sound energy to the gas within the
regenerator. Yet another way for applying the pulse is
by means of a linear motor/compressor arrangement. Yet
another means to apply pulse is by means of a
loudspeaker. Another preferred means to apply pulse is
by means of a travelling wave engine. The pulse serves
to compress the pulse tube gas producing hot compressed
pulse tube gas at the hot end of the regenerator body
41. The hot pulse tube gas is cooled by indirect heat
exchange with heat transfer fluid 33 in heat exchanger
44 to produce warmed heat transfer fluid in stream 34
and to produce cooled compressed pulse tube gas for
passage through the remainder of the regenerator body.
Examples of fluids useful as the heat transfer fluid in
the practice of this invention include water, air,
ethylene glycol and the like.
The regenerator body contains heat transfer media.
Examples of suitable heat transfer media in the
practice of this invention include steel balls, wire
mesh, high density honeycomb structures, expanded
metals, lead balls, copper and its alloys, complexes of
rare earth element(s) and transition metals.
The heat transfer media is at a cold temperature,
generally within the range of from 10 to 280K at the
cold end to 200 to 310K at the warm end, having been
brought to this cold temperature in the second part of
the pulse tube sequence' which will be described more
fully below. As the cooled compressed pulse tube gas
passes through the regenerator body, it is further
cooled by direct contact with the cold heat transfer
media to produce warmed heat transfer media and further
cooled pulse tube gas, generally at a temperature
within the range of from 9 to 279K at the cold end to
199 to 309 at the warm end.
The further cooled pulse tube gas is passed from
the regenerator body 41 to pulse tube body 1 at the
cold end and is expanded through pulse tube heat
exchanger 42. As the further cooled pulse tube gas
passes into pulse tube body 1 at the cold end it
generates a gas pressure wave which flows toward the
warm end of pulse tube body 1 and compresses the gas
within the pulse tube, termed the pulse tube working
fluid, thereby heating the pulse tube working fluid.
Cooling fluid 35 is passed to heat exchanger 36
wherein it is warmed or vaporized by indirect heat
exchange with the pulse tube working fluid, thus
serving as a heat sink to cool the pulse tube working
fluid. Resulting warmed or vaporized cooling fluid is
withdrawn from heat exchanger 36 in stream 37.
Preferably cooling fluid 35 is water, air, ethylene
glycol or the like.
Attached to the warm end of pulse tube body 1 is a
line having orifice 38 leading to reservoir 39. The
compression wave of the pulse tube working fluid
contacts the warm end wall of the pulse tube body and
proceeds back in the second part of the pulse tube
sequence. Orifice 38 and reservoir 39 are employed to
maintain the pressure and flow waves in phase so that
the pulse tube generates net refrigeration during the
expansion and the compression cycles in the cold end of
pulse tube body 1. Other means for maintaining the
pressure and flow waves in phase which may be used in
the practice of this invention include inertance tube
and orifice, expander, linear alternator, bellows
arrangements, and a work recovery line with a mass flux
suppressor. In the expansion sequence, the pulse tube
gas expands through pulse tube heat exchanger 42 to
produce cold pulse tube gas at the cold end of the
pulse tube body 1. The expanded gas reverses its
direction such that it flows from the pulse tube body
toward regenerator body 42.
The pulse tube gas emerging from pulse tube heat
exchanger 42 is passed to regenerator body 41 wherein
it directly contacts the heat transfer media within the
regenerator body to produce the aforesaid cold heat
transfer media, thereby completing -the second part of
the pulse tube refrigerant sequence and putting the
regenerator into condition for the first part of a
subsequent pulse tube refrigeration sequence.
In the practice of this invention the pulse tube
body contains only gas for the transfer of the pressure
energy from the expanding pulse tube gas at the cold
end for the heating of the pulse tube working fluid at
the warm end of the pulse tube. That is, pulse tube
refrigerator 40 contain no moving parts such as are
used with a piston arrangement. The operation of the
pulse tube without moving parts- is a significant
advantage of this invention. The pulse tube may have a
taper to aid adjustment of the proper phase angle
between the pressure and flow waves. In addition, the
pulse tube may have a passive displacer to help in
separating the ends of the pulse tube. Furthermore,
the pulse tube will have a connecting line between the
pulse tube warm end and pressure wave line 45,
replacing the orifice and reservoir with a mass flux
suppressor such as a bellows arrangement to recover
lost work.
Heat transfer medium is passed in line 7 to pump 4
and from there is pumped through line 5 to pulse tube
heat exchanger 42 wherein it is cooled by indirect heat
exchange with the cold pulse tube gas which was
expanded into pulse tube body 1 from regenerator body
41. Examples of heat transfer medium suitable for use
in the practice of this invention include helium, neon,
hydrogen, atmospheric gases such as nitrogen, argon and
air, hydrocarbons such as methane, ethane, ethylene,
liquefied natural gas and liquefied petroleum gas,
fluorocarbon's and hydrofluorocarbons such as carbon
tetrafluoride and fluoroform, selected fluoroethers and
hydrofluoroethers, and mixtures comprising one or more
of the above.
Resulting cooled heat transfer medium is passed
from pulse tube heat exchanger 42 in line 6 to
forecooling heat exchanger 30 wherein it is warmed
serving to cool by indirect heat exchange refrigeration
fluid passed to heat exchanger 30 in line 13. The
warmed heat transfer medium is withdrawn from
forecooling heat exchanger 30 in line 7 and
recirculated back to the pulse tube refrigerator as was
previously described.
In the embodiment of the invention illustrated in
Figure 1 the system used to provide lower level
refrigeration to the refrigeration fluid is a multiple
component refrigeration system wherein a multiple
component refrigeration fluid recirculating in a
circuit undergoes compression and expansion steps and
delivers refrigeration to a heat load. In this
embodiment the multicomponent refrigeration fluid
preferably comprises at least one atmospheric gas
preferably nitrogen, argon and/or neon, and preferably
at least one fluorine containing compound having up to
six carbon atoms such as fluorocarbons,
hydrofluorocarbons, hydrochlorofluorocarbons,
fluoroethers and hydrofluoroethers, and/or at least one
hydrocarbon having up to five carbon atoms.
Referring back now to Figure 1, compressed
refrigeration fluid 13, which in this embodiment is a
multicomponent refrigeration fluid, is cooled to a
first temperature within the range of from 10 to 280K
by passage through forecooling heat exchanger 30 by
indirect heat exchange with the aforediscussed warming
heat transfer medium. Resulting cooled refrigeration
fluid 14 is further cooled by passage through heat
exchanger 31 and resulting refrigeration fluid stream
15 undergoes expansion through an expansion device,
such as Joule-Thomson valve 16, to generate
refrigeration. The refrigeration provided to the
refrigeration fluid by the expansion through valve 16
results in the establishment of cold refrigeration
fluid 17 at a second temperature, which is lower than
the first temperature, and is within the range of from
3 to 150K. The cold refrigeration fluid 17 is passed
to heat exchanger 32 wherein it is warmed thereby
passing refrigeration from the cold refrigeration fluid
to heat load 3. Examples of the uses of the
refrigeration passed into heat lead 3 include
superconducting cable cooling, industrial gas
liquefaction, reliquefaction, propellant densification,
air separation, and cryogenic gas separation.
The resulting warmed refrigeration fluid 18 is'•
further warmed by passage through heat exchanger 31 and
then resulting stream 19 is still further warmed by
passage through forecooling heat exchanger 30 wherein
it assists in the cooling of the refrigeration fluid
down to the first temperature. Resulting refrigeration
fluid 20 from heat exchanger 30 is compressed to a
pressure generally within the range of from 50 to 2000
pounds per square inch absolute (psia) in compressor
10. Compressed refrigeration fluid 11 is cooled of the
heat of compression by passage through cooler 12 and
resulting compressed refrigeration fluid 13 is passed
to forecooling heat exchanger 30 and the refrigeration
cycle repeats.
Figures 2 and 3 illustrate other preferred
embodiments of the invention. The numerals in Figures
2 and 3 are the same as those of Figure 1 for the
common elements and these common elements will not be
discussed again in detail. Figure 2 illustrates an
embodiment wherein lower level refrigeration is
provided to the refrigeration fluid using a Brayton
refrigerator and Figure 3 illustrates an embodiment
wherein lower level refrigeration is provided to the
refrigeration fluid using a magnetic refrigerator.
Referring now to Figure 2, Brayton system working
fluid is compressed in Brayton system compressor 70 and
the heat of compression is removed (not shown).
Resulting refrigeration fluid 13 is desuperheated in
heat exchanger 30 by returning stream 19 and by stream
6 to the first temperature. Resulting stream 14 is
further desuperheated in heat exchanger 31 and expanded
isentropically by Brayton system expander 71 to
generate refrigeration and cool the refrigeration fluid
or Brayton system working fluid to the second
temperature. Resulting working fluid 17 provides
refrigeration to heat load 3 in heat exchanger 32 and
is then returned to the suction of Brayton system
compressor 70.
Referring now to Figure 3, magnetic refrigerator
100 comprises magnetizable material bed 101, moveable
strong electromagnet or superconducting magnet 102,
pistons 103 and 104, a cold heat exchanger 105 and a
hot heat exchanger 106. Examples of magnetizable
material which can be used in the practice of this
invention include GdNi2, GdZn2, GdTi03, Gd2Nii7, GdAl2,
GdMg, GdCd, Gd4C03, GdGa, Gd5Si4, and GdZn. The void
space surrounding the magnetic bed particles in bed 101
and the volumes in piston cylinders 107 and 108 are
filled with working fluid, examples of which include
helium, neon, nitrogen, argon, methane,
carbontetrafluoride fluorocarbons, hydrofluorocarbons,
fluoroethers and hydrofluoroethers.
At the beginning of the cycle cold heat exchanger
105 is initially at a low temperature and hot heat
exchanger 106 is at a warmer temperature. Magnet 102
is used to magnetize bed 101. The magnetocaloric
effect causes each magnetic particle in bed 101 to warm
slightly. Pistons 103 and 104 are moved to their
extreme right position causing the enclosed working
fluid, e.g. helium gas, to flow from the left cylinder
107, through cold heat exchanger 105, magnetic
refrigerator bed 101 and hot heat exchanger 106 to fill
the volume in cylinder 108. The particles in bed 101
are cooled by the flowing gas, and the gas in turn is
warmed. Heat from the gas is transferred to cooling
water as the gas flows through hot heat exchanger 106.
When the pistons have reached their extreme right
position the gas flow is stopped and the magnetic field
is removed, cooling bed 101 by the magnetocaloric
effect. Pistons 103 and 104 are moved back to their
extreme left positions causing the helium gas to flow
from cylinder 108, through hot heat exchanger 106,
magnetic refrigerator bed 101 and cold heat exchanger
105 into cylinder volume 107. The helium gas is cooled
by direct heat exchange as it passes through bed 101,
and is warmed in cold heat exchanger 105 as it provides
refrigeration into cooled refrigeration fluid to
produce the cold refrigeration fluid at the second
temperature which is further processed as was
previously described. In this embodiment the
refrigeration fluid is passed through the refrigeration
fluid circuit by operation of pump 72.
In Table 1 there is tabulated the calculated
energy requirements, in kilojoules per kilogram, to
cool helium to 4.3K using each of the three illustrated
embodiments of the invention wherein the pulse tube
refrigerator generates refrigeration from 300K to 50K
and each of the multicomponent refrigerant cycle (A),
Brayton refrigerator (B) and magnetic refrigerator (C)
generate the refrigeration from 50K to 4.3K. For
comparative purposes there is also shown, as
comparative example D, the energy requirements for
going from 300K to 4.3K using only a pulse tube system.
As can be seen, the hybrid refrigeration system of this
invention with the upstream pulse tube refrigerator
enables a significant reduction in the energy
requirements for the provision of comparable
refrigeration over systems which employ only pulse tube
refrigeration.
Although the invention has been described in
detail with reference to certain preferred embodiments,
those skilled in the art will recognize that there are
other embodiments of the invention within the spirit and the scope of the claims.




WE CLAIM:
1. A method for providing refrigeration to a heat load comprising:
(A) compressing pulse tube gas (45) to produce hot compressed pulse tube gas, cooling (44) the compressed pulse tube gas, and expanding the cooled pulse tube gas to produce cold pulse tube gas;
(B) warming (42) the cold pulse tube gas by indirect heat exchange with heat transfer medium (5) to produce cooled heat transfer medium (6), and warming (30) the cooled heat transfer medium by indirect heat exchange with refrigeration fluid (13) to produce cooled refrigeration fluid {14) at a first temperature within the range of from 20 to 280K;
(C) providing refrigeration into the cooled refrigeration fluid to
produce cold refrigeration fluid (17) at a second temperature lower than said
first temperature and within the range of from 3 to 150K; and
(D) warming (32) the cold refrigeration fluid by passing
refrigeration from the cold refrigeration fluid into a heat load.
2. The method as claimed in claim 1, wherein the refrigeration fluid is a multicomponent refrigeration fluid.
3. The method as claimed in claim 1, wherein refrigeration is provided into the refrigeration fluid by expanding (16, 71) the refrigeration fluid.
4. The method as claimed in claim 3, wherein the expansion of the refrigeration fluid is isentropic expansion (71).

5. The method as claimed in claim 1, wherein refrigeration is provided into the refrigeration fluid by magnetizing a bed of magnetizable material (101), demagnetizing the magnetized bed material (101), cooling working fluid by bringing the working fluid into contact with the demagnetized bed material (101), and cooling the refrigeration fluid (15) by indirect heat exchange with the cooled working fluid.
6. Apparatus for carrying out the method as claimed in claim 1, for providing refrigeration to a heat load comprising:
(A) a pulse tube refrigerator (40)
comprising a regenerator body (41), a pulse tube body (1) having a pulse tube heat exchanger (42), means (43) for generating pressurized gas for oscillating flow within the regenerator body, and means for expanding gas within the pulse tube body through the pulse tube heat exchanger;
(B) a forecooling circuit comprising a forecooling heat exchanger (30), means for passing heat transfer medium (6) from the pulse tube heat exchanger (42) to the forecooling heat exchanger (30) and means for passing heat transfer medium (7) from the forecooling heat exchanger (30) to the pulse tube heat exchanger (42);
(C) means for passing refrigeration fluid (13) to the forecooling heat exchanger (30), and means (16, 71, 100) for providing refrigeration into the refrigeration fluid (15) downstream of the forecooling heat exchanger (30); and

(D) a heat load and means (32) for passing refrigeration from the refrigeration fluid into the heat load.
7. The apparatus as claimed in claim 6, comprising a compressor (10, 70) and an expansion device (16, 71), wherein the means for passing refrigeration fluid to the forecooling heat exchanger (30) having the compressor (10, 70), and the means for providing refrigeration into the refrigeration fluid downstream of the forecooling heat exchanger (30) includes the expansion device (16, 71).
8. The apparatus as claimed in claim 6, comprising a magnetic refrigerator (100) having a bed of magnetizable material (101), means (102) for magnetizing and demagnetizing the bed of magnetizable material (101), and containing working fluid for contact with the bed of magnetizable material; wherein the means for providing refrigeration into the refrigeration fluid downstream of the forecooling heat exchanger (30) having means (105) for passing refrigeration fluid in indirect heat exchange with said working fluid.

Documents:

01161-delnp-2003-abstract.pdf

01161-delnp-2003-assignments.pdf

01161-delnp-2003-claims.pdf

01161-delnp-2003-correspondence-others.pdf

01161-delnp-2003-description (complete).pdf

01161-delnp-2003-drawings.pdf

01161-delnp-2003-form-1.pdf

01161-delnp-2003-form-18.pdf

01161-delnp-2003-form-2.pdf

01161-delnp-2003-form-3.pdf

01161-delnp-2003-form-5.pdf

01161-delnp-2003-gpa.pdf

01161-delnp-2003-pct-101.pdf

01161-delnp-2003-pct-210.pdf

01161-delnp-2003-pct-304.pdf

01161-delnp-2003-pct-332.pdf

01161-delnp-2003-pct-409.pdf

01161-delnp-2003-pct-416.pdf

1161-DELNP-2003-Abstract 22-02-2008.pdf

1161-DELNP-2003-Claims 22-02-2008.pdf

1161-DELNP-2003-Claims-(30-06-2008).pdf

1161-DELNP-2003-Correspondence-Others-(30-06-2008).pdf

1161-DELNP-2003-Corrspondence-Others 22-02-2008.pdf

1161-DELNP-2003-Description (Complete) 22-02-2008.pdf

1161-DELNP-2003-Description (Complete) 30-06-2008.pdf

1161-DELNP-2003-Drawings 22-02-2008.pdf

1161-DELNP-2003-Form-1 22-02-2008.pdf

1161-DELNP-2003-Form-2 22-02-2008.pdf

1161-DELNP-2003-Form-3 22-02-2008.pdf

1161-DELNP-2003-GPA 22-02-2008.pdf

1161-DELNP-2003-GPA-(30-06-2008).pdf

1161-DELNP-2003-Petiton-137 22-02-2008.pdf


Patent Number 222101
Indian Patent Application Number 01161/DELNP/2003
PG Journal Number 32/2008
Publication Date 08-Aug-2008
Grant Date 21-Jul-2008
Date of Filing 25-Jul-2003
Name of Patentee PRAXAIR TECHNOLOGY, INC.
Applicant Address 39 OLD RIDGEBURY ROAD, DANBURY, CONNECTICUT 06810-5113, U.S.A.
Inventors:
# Inventor's Name Inventor's Address
1 ARUN ACHARYA 85 TWILIGHT LANE, EAST AMHERST, NEW YORK 14051, USA.
2 JOHN H. ROYAL 102 SETTLERS ROW, GRAND ISLAND, NEW YORK 14072, USA.
3 DANTE PATRICK BONAQUIST 1036 RANSOM ROAD, GRAND ISLAND, NEW YORK 14072, USA.
4 BAYRAM ARMAN 16 THE COMMONS, GRAND ISLAND, NEW YORK 14072, USA
5 CHRISTIAN FRIEDRICH GOTTZMANN 5308 THOMPSON ROAD, CLARENCE, NEW YORK 14031, USA
PCT International Classification Number F25B 21/02
PCT International Application Number PCT/US02/02496
PCT International Filing date 2002-01-30
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 09/778,830 2001-02-08 U.S.A.