U.S. patent application number 11/742808 was filed with the patent office on 2007-09-13 for mixed gas refrigerant system for sensor cooling below 80 k.
This patent application is currently assigned to RAYTHEON COMPANY. Invention is credited to LAWRENCE SOBEL.
Application Number | 20070209371 11/742808 |
Document ID | / |
Family ID | 38477564 |
Filed Date | 2007-09-13 |
United States Patent
Application |
20070209371 |
Kind Code |
A1 |
SOBEL; LAWRENCE |
September 13, 2007 |
MIXED GAS REFRIGERANT SYSTEM FOR SENSOR COOLING BELOW 80 K
Abstract
The present invention discloses multi-component gas mixtures
adapted to provide condensed phase cryogenic refrigerants with
normal boiling points below about 80.degree. K. for cooling sensor
device components. Exemplary gas mixtures generally include 19-40%
Ar and 20.1-80.5% Ne. Open-loop Joule-Thomson systems in accordance
with the present invention may be suitably adapted (with varying
relative mass ratios of cryogenic gas mixtures) for cooling sensor
devices to temperatures between 27.degree. K. (100% Neon) and about
80.degree. K. (0% Neon).
Inventors: |
SOBEL; LAWRENCE; (Tucson,
AZ) |
Correspondence
Address: |
NOBLITT & GILMORE, LLC.
4800 NORTH SCOTTSDALE ROAD
SUITE 6000
SCOTTSDALE
AZ
85251
US
|
Assignee: |
RAYTHEON COMPANY
Waltham
MA
|
Family ID: |
38477564 |
Appl. No.: |
11/742808 |
Filed: |
May 1, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11374806 |
Mar 13, 2006 |
|
|
|
11742808 |
May 1, 2007 |
|
|
|
Current U.S.
Class: |
62/51.2 |
Current CPC
Class: |
C09K 5/041 20130101;
F25B 9/006 20130101; F25B 9/02 20130101 |
Class at
Publication: |
062/051.2 |
International
Class: |
F25B 19/02 20060101
F25B019/02 |
Claims
1. An open-loop Joule-Thomson system for cooling sensor devices to
temperatures below about 80.degree. K., said system comprising: a
vessel containing a pressurized mixture of cryogenic gas selected
from the group consisting of Ar and Ne; a counter-flow heat
exchanger configured to exchange heat between pre- and
post-expanded cryogenic gas; a reservoir configured to collect and
boil-off post-expanded cryogenic gas; an isenthalpic expansion
valve configured to receive a pre-expanded cryogenic gas from said
counter-flow heat exchanger for isenthalpic expansion into said
reservoir; and a sensor device component in contact with said heat
exchanger for cooling said sensor device.
2. The open-loop Joule-Thomson system of claim 1, wherein said
vessel is configured for regulated release of said cryogenic
gas.
3. The open-loop Joule-Thomson system of claim 1, wherein said
reservoir comprises an evaporator-reservoir.
4. The open-loop Joule-Thomson system of claim 1, wherein the
molecular weight fraction of Ar is between about 19% to about
40%.
5. The open-loop Joule-Thomson system of claim 1, wherein the
molecular weight fraction of Ne is between about 20.1% to about
81.0%.
6. The open-loop Joule-Thomson system of claim 1, wherein the
normal boiling point of the condensed phase of said cryogenic gas
mixture is between about 27.degree. K. and 77.degree. K.
7. A method for cooling sensor devices to temperatures below about
80.degree. K., said method comprising the steps of: providing a
vessel containing a pressurized mixture of cryogenic gas selected
from the group consisting of Ar and Ne; providing a counter-flow
heat exchanger configured to exchange heat between pre- and
post-expanded cryogenic gas; providing a reservoir configured to
collect and boil-off post-expanded cryogenic gas; providing an
isenthalpic expansion valve configured to receive a pre-expanded
cryogenic gas from said counter-flow heat exchanger for isenthalpic
expansion into said reservoir; and providing a sensor device
component in contact with said heat exchanger for cooling said
sensor device.
8. The method of claim 7, wherein said vessel is configured for
regulated release of said cryogenic gas.
9. The method of claim 7, wherein said reservoir comprises an
evaporator-reservoir.
10. The method of claim 7, wherein the molecular weight fraction of
Ar is between about 19% to about 40%.
11. The method of claim 7, wherein the molecular weight fraction of
Ne is between about 20.1% to about 81.0%.
12. The method of claim 7, wherein the normal boiling point of the
condensed phase of said cryogenic gas mixture is between about
27.degree. K. and 77.degree. K.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part of and claims
priority to U.S. patent application Ser. No. 11/374,806 filed on
Mar. 13, 2006 by Lawrence D. Sobel in the United States Patent and
Trademark Office.
FIELD OF INVENTION
[0002] The present invention generally concerns refrigerant
systems; and more particularly, representative and exemplary
embodiments of the present invention generally relate to the
cooling of sensor devices with mixed gas cooling systems.
BACKGROUND OF INVENTION
[0003] Freon-type pure gases have been generally used in
closed-cycle refrigeration systems operating within household and
commercial refrigeration temperature regimes. More recently, mixed
gases (frequently utilizing Freon as one of the constituent
components) have also been employed. Such consumer-level
refrigeration systems typically employ equipment that is suitably
adapted to operate within desired pressure ratios and temperature
ranges.
[0004] When operating cooling systems in cryogenic temperature
regimes, condensed phase refrigerants having normal boiling point
temperatures below 120.degree. K. (e.g., nitrogen, helium, methane,
and the like) have been used. These cryogenic gases have ordinarily
required the use of high pressure gas systems involving multi-stage
compressors or high pressure oil-less compressors. Examples of
these systems include pulse tube cryo-coolers and stirling
cryo-coolers. These types of active refrigeration systems have
become more expensive to manufacture and operate, and require
frequent maintenance.
[0005] In order to provide cryogenic systems which are less costly
and more efficient, there have been mixed gas refrigerants proposed
for use within cryogenic temperature ranges. Many such mixed gas
systems have been proposed. These typically combine conventional
and well-known cryogenic refrigerants with various hydrocarbons,
including methane, ethane, propane, and isobutene, in various
combinations.
[0006] U.S. Pat. No. 5,441,658 to Boyarsky et al. discloses mixed
gas refrigerants consisting of mixtures of 30-50% by molar weight
of nitrogen combined with at least some, but less than 20% methane
by mole fraction, at least 30% propane by mole fraction, and enough
ethane or ethylene to balance the mixture. Russian Patent No.
627,154 suggests a mixed gas refrigerant combining nitrogen with
various hydrocarbons (e.g., 25-40% nitrogen by molar weight, 20-35%
methane by molar weight, 15-35% ethane by molar weight, and 25-45%
propane by molar weight. Another reference which has suggested a
combination of the same ingredients, but in different proportions,
is U.K. Patent No. 1,336,892.
[0007] There are numerous combinations of conventional cryogenic
refrigerants. Existing systems, however, are generally only
suitable for operation above about 80.degree. K.
[0008] Conventional cryogenic fluids with normal boiling points
above about 80.degree. K. generally include: N.sub.2, air, CO, F,
Ar, O.sub.2, CH.sub.4, Kr, R14, O.sub.3, Xe, C.sub.2H.sub.4,
BF.sub.3, N.sub.2O, C.sub.2H.sub.6, HCl, C.sub.2H.sub.2, CHF.sub.3,
1,1-C.sub.2H.sub.2F.sub.2, R13, CO.sub.2, Rn, C.sub.3H.sub.8,
C.sub.4H.sub.10, and C.sub.5H.sub.12. Those with normal boiling
points below about 27.degree. K. generally include .sup.3He,
.sup.4He, H.sub.2, .sup.2H, .sup.3H, and Ne. For cryogenic
applications between 27.degree. K and 80.degree. K, none of these
pure compounds provide a suitable condensed phase normal boiling
point temperature.
[0009] Consequently, only active refrigeration systems, such as
pulse tube cyro-coolers and stirling cryo-coolers, are currently in
use for cryogenic applications below 80.degree. K. Thus, there is a
need for more reliable and less hardware-dependent systems for
cryogenic applications below 80.degree. K.
SUMMARY OF THE INVENTION
[0010] In various representative aspects, the present invention
discloses multi-component mixed gas systems suitably adapted to
provide condensed phase cryogenic refrigerants with normal boiling
points below 80.degree. K. for cooling sensor devices. Exemplary
gas mixture components generally include 19-40% argon and
20.1-80.5% neon. The disclosed multi-component gas mixture systems
may be suitably adapted (with varying component mass ratios) for
operation in sensor cooling systems between about 27.degree. K.
(100% Neon) and about 80.degree. K. (0% Neon).
[0011] Advantages of the present invention will be set forth in the
Detailed Description which follows and may be apparent from the
Detailed Description or may be learned by practice of exemplary
embodiments of the invention. Still other advantages of the
invention may be realized by means of any of the instrumentalities,
methods or combinations particularly pointed out in the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Representative elements, operational features, applications
and/or advantages of the present invention reside inter alia in the
details of construction and operation as more fully hereafter
depicted, described and claimed--reference being made to the
accompanying drawings forming a part hereof, wherein like numerals
refer to like parts throughout. Other elements, operational
features, applications and/or advantages will become apparent in
light of certain exemplary embodiments recited in the detailed
description, wherein:
[0013] FIG. 1 representatively illustrates a schematic of an
open-loop Joule-Thomson cooling system in accordance with an
exemplary embodiment of the present invention; and
[0014] FIG. 2 representatively illustrates a temperature/entropy
diagram for an open-loop Joule-Thomson cooling system in accordance
with an exemplary embodiment of the present invention.
[0015] Elements in the Figures are illustrated for simplicity and
clarity and have not necessarily been drawn to scale. For example,
the dimensions of some of the elements in the Figures may be
exaggerated relative to other elements to help improve
understanding of various embodiments of the present invention.
Furthermore, the terms "first", "second", and the like herein, if
any, are used inter alia for distinguishing between similar
elements and not necessarily for describing a sequential or
chronological order. Moreover, the terms "front", "back", "top",
"bottom", "over", "under", "forward", "aft", and the like in the
Description and/or in the claims, if any, are generally employed
for descriptive purposes and not necessarily for comprehensively
describing exclusive relative position. Any of the preceding terms
so used may be interchanged under appropriate circumstances such
that various embodiments of the invention described herein, for
example, may be capable of operation in other configurations and/or
orientations than those explicitly illustrated or otherwise
described.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0016] The following representative descriptions of the present
invention generally relate to exemplary embodiments and the
inventor's conception of the best mode, and are not intended to
limit the scope, applicability or configuration of the invention in
any way. Rather, the following description is intended to provide
convenient illustrations for implementing various embodiments of
the invention. As will become apparent, changes may be made in the
function and/or arrangement of any of the elements described in the
disclosed exemplary embodiments without departing from the spirit
and scope of the invention.
[0017] A detailed description of a representative mixed gas
refrigerant cooling system is provided as a specific enabling
disclosure that may be generalized to any operational embodiment of
the disclosed invention.
[0018] The present invention may be described herein in terms of
multi-component gas mixtures and Joule-Thomson systems.
Multi-component gas mixtures, according to various aspects of the
present invention, generally comprise Argon (Ar) and Neon (Ne). It
should be appreciated that in accordance with various aspects of
the present invention, Ar and Ne comprise inversion temperatures
suitable for operation in Joule-Thomson systems. In accordance with
various aspects of the present invention, Ar may comprise an
inversion temperature of approximately 723.degree. K., and Ne may
comprise an inversion temperature of approximately 231.degree.
K.
[0019] In a representative embodiment, approximately 19% Ar by
molar weight may be combined and/or balanced with Ne. The resulting
multi-component mixture demonstrates a normal boiling point
temperature of approximately 49.degree. K.
[0020] In another representative embodiment, approximately 40% by
molar weight Ar may be combined and/or balanced with Ne. The
resulting multi-component mixture demonstrates a normal boiling
point temperature of approximately 60.degree. K.
[0021] Multi-component gas mixtures in accordance with various
aspects of the present invention may be implemented as refrigerants
in sensor cooling systems. It should be appreciated that when
implemented in sensor cooling systems, multi-component gas mixtures
may generally be employed as refrigerants at temperatures below the
inversion temperatures of the discrete gaseous components taken by
themselves.
[0022] Sensor cooling systems in accordance with various aspects of
the present invention may include Joule-Thomson cooling systems,
adiabatic expansion systems and/or the like. Referring now to FIG.
1, it will be appreciated that a representative sensor cooling
system 100, in accordance with various aspects of the present
invention, may comprise conventional gas vessel 105, counter-flow
heat exchanger 110, isenthalpic expansion valve 115 and reservoir
120.
[0023] It will be appreciated that gas vessel 105, in accordance
with various aspects of the present invention, may comprise any
suitable material for housing the multi-component mixture. Suitable
materials may include, for example: glass, metal, polymers,
plastics, ceramics and/or the like. In a representative embodiment
of the present invention, gas vessel 105 may comprise an insulated
vessel. In another representative embodiment, gas vessel 105 houses
a multi-component gas mixture in accordance with representative
embodiments of the present invention, and may be connected to
counter-flow heat exchanger 110.
[0024] It will be appreciated that counter-flow heat exchanger 110,
in accordance with various representative aspects of the present
invention, may comprise any heat exchange system or sub-system,
whether now known or hereafter discovered, or otherwise described.
The counter-flow heat exchanger 110, in accordance with various
aspects of the present invention, may comprise any suitable
mechanism for heat transfer from one fluid to another, where the
fluid flow fields are configured roughly perpendicular to each
other. Counter-flow heat exchanger 110 may include shell and/or
tube heat exchangers, plate heat exchangers, plate heat exchangers,
regenerative heat exchangers, adiabatic wheel heat exchangers,
fluid heat exchangers, dynamic scraped surface heat exchangers,
and/or the like.
[0025] It should be appreciated that in accordance with various
aspects of the present invention, cooling may be generally achieved
by expansion of a gas (or mixture of gases) thru expansion valve
115. Any materials suitable for regulating the flow of gas and/or
isenthalpic expansion of gas thru expansion valve 115 may be
alternatively, conjunctively or sequentially employed to achieve
cooling. In a representative embodiment of the present invention,
expansion valve 115 may be insulated to substantially prevent heat
transfer to and/or from the gas.
[0026] It should be appreciated that in accordance with various
representative aspects of the present invention,
evaporator-reservoir 120 may comprise any mechanism suitable for
boiling-off the multi-component gas mixture of the present
invention. In a representative embodiment of the present invention,
evaporator-reservoir 120 may substantially maintain a relatively
constant temperature of the multi-component gas mixture.
[0027] The cryogenic gas mixture is initially contained in vessel
105. After release from vessel 105, the gas proceeds via path 102
to heat exchanger 110. The gas absorbs heat in heat exchanger 110
then proceeds via path 112 to expansion valve 115, where the gas
undergoes isenthalpic expansion to cool the gas mixture before
proceeding via path 117 to reservoir 120. Cryogenic gas in
reservoir 120 is collected and boiled-off where the gas then
proceeds via path 122 to heat exchanger 110 prior to discharge as
exhaust via path 127. Heat exchanger 110 may be placed in contact
with sensor device components to provide cooling thereof.
[0028] Referring now to FIG. 2, in a representative embodiment of
the present invention, changes in temperature as a function of
entropy may be observed as the cryogenic gas mixture moves through
the open-loop Joule-Thomson cooling system. As the gas mixture
passes through heat exchanger 110, the pressure remains relatively
constant over this path 205-210 as the temperature decreases. As
the gas mixture expands through expansion valve 115, the heat
remains relatively constant (i.e., isenthalpic expansion) over this
path 210-215 as the temperature decreases further. As the gas
mixture passes through reservoir 120, the gas is collected and
boiled-off at relatively constant temperature with entropy
generally increasing over this path 215-220. As the gas passes
through the counter-flow circuit of heat exchanger 110, the
pressure remains relatively constant over this path 220-225 as the
temperature increases. Through this process of isenthalpic
expansion, no extra work (mechanical or otherwise) is necessary to
affect a lowering in temperature and/or a cooling of the system
100.
[0029] Sensor cooling systems in accordance with representative
aspects of the present invention may be implemented to provide
cooling of, for example, long wave infrared sensors. Sensor cooling
systems in accordance with representative embodiments of the
present invention may generally provide safer alternatives,
inasmuch as no highly reactive and/or dangerous fluids are
employed. In yet a further embodiment of the present invention,
representative sensor cooling systems provide customizable
refrigeration solutions which may be suitably adapted for a variety
of sensors, electronics, sensor systems, and/or the like. In yet a
further representative aspect of the present invention, sensor
cooling systems in accordance with the present invention generally
provide the ability to vary refrigeration temperature regimes
without hardware (e.g., device-level or system-level)
modifications.
[0030] In the foregoing specification, the invention has been
described with reference to specific exemplary embodiments;
however, it will be appreciated that various modifications and
changes may be made without departing from the scope of the present
invention as set forth in the claims below. The specification is to
be regarded in an illustrative manner, rather than a restrictive
one and all such modifications are intended to be included within
the scope of the present invention. Accordingly, the scope of the
invention should be determined by the claims appended hereto and
their legal equivalents rather than by merely the examples
described above.
[0031] For example, the components and/or elements recited in any
apparatus claims may be assembled or otherwise operationally
configured in a variety of permutations to produce substantially
the same result as the present invention and are accordingly not
limited to the specific configuration recited in the claims.
[0032] Benefits, other advantages and solutions to problems have
been described above with regard to particular embodiments;
however, any benefit, advantage, solution to problem or any element
that may cause any particular benefit, advantage or solution to
occur or to become more pronounced are not to be construed as
critical, required or essential features or components of any or
all the claims.
[0033] As used herein, the terms "comprising", "having",
"including" or any contextual variant thereof, are intended to
reference a non-exclusive inclusion, such that a process, method,
article, composition or apparatus that comprises a list of elements
does not include only those elements recited, but may also include
other elements not expressly listed or inherent to such process,
method, article, composition or apparatus. Other combinations
and/or modifications of the above-described structures,
arrangements, applications, proportions, elements, materials or
components used in the practice of the present invention, in
addition to those not specifically recited, may be varied or
otherwise particularly adapted to specific environments,
manufacturing specifications, design parameters or other operating
requirements without departing from the general principles of the
same.
* * * * *