U.S. patent application number 13/053807 was filed with the patent office on 2011-09-29 for liquefied air refrigeration system for storage container.
This patent application is currently assigned to Wabash National, L.P.. Invention is credited to David Pickup.
Application Number | 20110232307 13/053807 |
Document ID | / |
Family ID | 44654791 |
Filed Date | 2011-09-29 |
United States Patent
Application |
20110232307 |
Kind Code |
A1 |
Pickup; David |
September 29, 2011 |
LIQUEFIED AIR REFRIGERATION SYSTEM FOR STORAGE CONTAINER
Abstract
A liquid refrigeration system for a thermally-insulated storage
container includes a tank configured to store liquid air therein, a
conduit system having a first end portion coupled to the tank and a
second end portion configured to be positioned within an interior
of the thermally-insulated storage container, a spray head coupled
to the second end portion of the conduit system, a control system
electrically coupled to the tank and the spray head to control the
flow of liquid air from the tank to the spray head.
Inventors: |
Pickup; David; (Lafayette,
IN) |
Assignee: |
Wabash National, L.P.
Lafayette
IN
|
Family ID: |
44654791 |
Appl. No.: |
13/053807 |
Filed: |
March 22, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61318607 |
Mar 29, 2010 |
|
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Current U.S.
Class: |
62/118 ; 62/149;
62/440; 62/452; 62/457.1; 62/457.9 |
Current CPC
Class: |
F25D 3/105 20130101 |
Class at
Publication: |
62/118 ; 62/440;
62/452; 62/149; 62/457.1; 62/457.9 |
International
Class: |
F25D 17/02 20060101
F25D017/02; F25D 11/00 20060101 F25D011/00; F25B 45/00 20060101
F25B045/00; F25D 3/10 20060101 F25D003/10 |
Claims
1. A liquid air refrigeration system for a thermally-insulated
storage container comprising: a tank configured to store liquid air
therein; a conduit system having a first end portion coupled to the
tank and a second end portion configured to be positioned within an
interior of the thermally-insulated storage container; a spray head
coupled to the second end of the conduit system; and a control
system electrically coupled to the tank and the spray head to
control the flow of liquid air from the tank to the spray head.
2. The liquid refrigeration system of claim 1, further comprising
another spray head coupled to the second end portion of the conduit
system.
3. The liquid refrigeration system of claim 1, further comprising
an evaporator coupled to the tank and the conduit system and
provided to convert the liquid air to a gaseous state.
4. The liquid refrigeration system of claim 1, further comprising a
temperature sensor configured to be positioned within the interior
of the thermally-insulated storage container, the temperature
sensor configured to monitor the temperature within the interior of
the thermally-insulated storage container.
5. The liquid refrigeration system of claim 4, wherein the
temperature sensor is electrically coupled to the control system,
and wherein the control system is configured to adjust the rate of
flow of the liquid air from the liquid air tank based upon the
temperature sensed by the temperature sensor.
6. The liquid refrigeration system of claim 5, wherein the tank
includes an inlet port, and inlet valve within the inlet port, an
outlet port, and an outlet valve within the outlet port, and
further wherein the inlet valve and outlet valve are each
electrically coupled to the control system such that the control
system is configured to open and close the outlet valve to adjust
the rate of flow of the liquid air from the liquid air tank.
7. The liquid refrigeration system of claim 1, further comprising a
second tank configured to store liquid air therein, the second tank
being coupled to the conduit system.
8. The liquid refrigeration system of claim 1, further comprising a
flow rate sensor configured to sense the flow rate of the liquid
air within the conduit system.
9. The liquid refrigeration system of claim 8, wherein the flow
rate sensor is electrically coupled to the control system, and
wherein the control system is configured to adjust the rate of flow
of the liquid air from the liquid air tank based upon the flow rate
sensed by the flow rate sensor.
10. A refrigerated storage trailer for transporting refrigerated
cargo comprising: a thermally-insulated storage container; and a
liquid air refrigeration system coupled to the thermally-insulated
storage container to supply liquid air to an interior of the
thermally-insulated container.
11. The refrigerated storage trailer of claim 10, wherein the
liquid air refrigeration system includes a tank configured to store
liquid air therein, and a conduit system having a first end portion
coupled to the tank and a second end portion positioned within the
interior of the thermally-insulated compartment.
12. The refrigerated storage trailer of claim 11, wherein the
liquid air refrigeration system further include a plurality of
spray heads coupled to the second end portion of the conduit
system.
13. The refrigerated storage trailer of claim 11, wherein the
conduit system includes a plurality of valves configured to control
the flow of the liquid air from the tank to the thermally-insulated
compartment.
14. The refrigerated storage trailer of claim 11, further
comprising a plurality of flow rate sensors configured to measure
the rate of flow of the liquid air through the conduit system
15. The refrigerated storage trailer of claim 10, further
comprising a control system electrically coupled to liquid air
refrigeration system to control the flow rate of liquid air into
the interior of the thermally-insulated container.
16. The refrigerated storage trailer of claim 15, further
comprising a temperature sensor positioned within the interior of
the thermally-insulated storage container, the temperature sensor
configured to monitor the temperature within the interior of the
thermally-insulated storage container, wherein the temperature
sensor is electrically coupled to the control system, and wherein
the control system is configured to adjust the rate of flow of the
liquid air from the liquid air tank based upon the temperature
sensed by the temperature sensor.
17. A method of refrigerating a storage container comprising:
providing a source of pressurized liquid air; injecting the liquid
air from the source through a spray head into the storage
container; and controlling the flow rate of the liquid air from the
source.
18. The method of claim 17, wherein controlling the flow rate
includes monitoring a temperature of an interior of the storage
container and adjusting the flow rate of the liquid air from the
source based on the monitored temperature.
19. The method of claim 17, wherein controlling the flow rate
includes monitoring the flow rate of liquid air from the source and
adjusting the flow rate of the liquid air from the source based on
the monitored flow rate.
20. The method of claim 17, further comprising determining if the
temperature within the storage container is within a predetermined
temperature range and generating a flow rate control signal in
response thereto.
21. The method of claim 20, further comprising changing the flow
rate of the liquid air from the source in response to the flow rate
control signal.
22. A liquid air refrigeration system for a thermally-insulated
storage container comprising: a liquid air refrigeration system;
and a liquid air control system electrically coupled to the liquid
air refrigeration system, the control system comprising (i) a
processing unit, and (ii) a memory unit electrically coupled to the
processing unit, the memory unit having stored therein a plurality
of instructions which, when executed by the processing unit, causes
the processing unit to: (a) operate the liquid air refrigeration
system so as to advance liquid air from a liquid air storage tank
to a thermally-insulated interior of a trailer, (b) determine if
the temperature within the thermally-insulated interior of the
trailer is within a predetermined temperature range and generating
a flow rate signal in response thereto, and (c) change the flow
rate of the liquid air from the liquid air storage tank to the
thermally-insulated interior of the trailer in response to the flow
rate signal.
Description
[0001] This application claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Patent Application Ser. No.
61/318,607 entitled LIQUEFIED AIR REFRIGERATION SYSTEM FOR STORAGE
CONTAINER, the entirety of which is hereby incorporated by
reference herein.
FIELD OF THE INVENTION
[0002] The present invention relates generally to storage
containers, such as static or mobile storage containers. In
particular, the present invention relates to a refrigeration system
for thermally insulated static or mobile storage containers.
BACKGROUND
[0003] Many storage containers, including both static and mobile
storage containers, are thermally insulated in order to allow the
container to be cooled or refrigerated. Such insulated containers
are frequently used for the storage and preservation of products
such as food stuffs and biological materials, for example,
requiring low or sub zero temperatures. Oftentimes, such low
temperatures are achieved through the use of electrical or engine
driven refrigeration systems. Alternatively, liquid cryogenic
gasses in both direct and indirect applications maybe used as
well.
[0004] Cryogenic gas refrigeration systems typically use carbon
dioxide, nitrogen, or other non-breathable gases as the
refrigerant. However, these gases, in the concentrations achieved
in the direct application systems in which the cold gas is
introduced directly into the container result in depletion of
oxygen levels below that required to support human life. Therefore,
and prior to entry to the container, the gasses must either be
vented or the entrant must wear a breathing apparatus. Furthermore,
the container is typically also equipped with devices to monitor
the oxygen level. Such devices may operate to provide a warning of
inadequacy for sustainment of life and/or to provide a barrier to
entry into the container in the event of lower than life sustaining
oxygen levels. Other cryogenic gas refrigeration systems for
medical imaging and particle physics, for example, may use liquid
helium in order to achieve super cold temperatures.
[0005] Alternatively, indirect cryogenic refrigerant systems
operate such that the refrigerant gasses are circulated through a
heat exchanger and do not directly enter the container. However, in
the event of a heat exchanger failure, such systems may also
present an asphyxiation hazard which needs to be protected
against.
SUMMARY
[0006] The present invention may comprise one or more of the
features recited in the attached claims, and/or one or more of the
following features and combinations thereof.
[0007] According to one aspect of the present disclosure a liquid
air refrigeration system for a thermally-insulated storage
container includes a tank configured to store liquid air therein, a
conduit system having a first end portion coupled to the tank and a
second end portion configured to be positioned within an interior
of the thermally-insulated storage container, a spray head coupled
to the second end portion of the conduit system, and a control
system electrically coupled to the tank and the spray head to
control the flow of liquid air from the tank to the spray head.
[0008] In one illustrative embodiment, the liquid refrigeration
system may further include another spray head coupled to the second
end portion of the conduit system.
[0009] In another illustrative embodiment, the liquid refrigeration
system may further include an evaporator coupled to the tank and
the conduit system. Illustratively, the evaporator may operate to
convert the liquid air to a gaseous state.
[0010] In still another illustrative embodiment, the liquid
refrigeration system may further include a temperature sensor
configured to be positioned within the interior of the
thermally-insulated storage container. Illustratively, the
temperature sensor may be configured to monitor the temperature
within the interior of the thermally-insulated storage container.
Further illustratively, the temperature sensor may be electrically
coupled to the control system such that the control system may be
configured to adjust the rate of flow of the liquid air from the
liquid air tank based upon the temperature sensed by the
temperature sensor. Continuing, the tank may include an inlet port,
and inlet valve within the inlet port, an outlet port, and an
outlet valve within the outlet port. Illustratively, the inlet
valve and outlet valve may each be electrically coupled to the
control system such that the control system may be configured to
open and close the outlet valve to adjust the rate of flow of the
liquid air from the liquid air tank.
[0011] In another illustrative embodiment, the liquid refrigeration
system may further include a second tank configured to store liquid
air therein. Illustratively, the second tank may be coupled to the
conduit system.
[0012] In still another illustrative embodiment, the liquid
refrigeration system may further include a flow rate sensor
configured to sense the flow rate of the liquid air within the
conduit system. Illustratively, the flow rate sensor may be
electrically coupled to the control system such that control system
may be configured to adjust the rate of flow of the liquid air from
the liquid air tank based upon the flow rate sensed by the flow
rate sensor.
[0013] According to another aspect of the present disclosure, a
refrigerated storage trailer includes a thermally-insulated
container and a liquid air refrigeration system coupled to the
thermally-insulated container to supply liquid air to an interior
of the thermally-insulated container.
[0014] In one illustrative embodiment, the liquid air refrigeration
system may include a tank configured to store liquid air therein,
and a conduit system having a first end portion coupled to the tank
and a second end portion positioned within the interior of the
thermally-insulated storage container. The conduit system may
include a plurality of valves configured to control the flow of the
liquid air from the tank to the thermally-insulated
compartment.
[0015] Further illustratively, the liquid air refrigeration system
may also include a plurality of spray heads coupled to the second
end portion of the conduit system. The refrigerated storage trailer
may also include a control system electrically coupled to liquid
air refrigeration system to control the flow rate of liquid air
into the interior of the thermally-insulated container.
Illustratively, the refrigerated storage trailer may also include a
temperature sensor positioned within the interior of the
thermally-insulated storage container. The temperature sensor may
be configured to monitor the temperature within the
thermally-insulated storage container and may be electrically
coupled to the control system such that the control system may
adjust the rate of flow of the liquid air from the liquid air tank
based upon the temperature sensed by the temperature sensor.
[0016] In another illustrative embodiment, the refrigerated storage
trailer may also include a plurality of flow rate sensors
configured to measure the rate of flow of the liquid air through
the conduit system.
[0017] According to still another aspect of the present disclosure,
a method of refrigerating a storage container includes providing a
source of pressurized liquid air, injecting the liquid air from the
source through a spray head into the storage container, and
controlling the flow rate of the liquid air from the source.
[0018] In one illustrative embodiment, controlling the flow rate
may include monitoring a temperature of an interior of the storage
container and adjusting the flow rate of the liquid air from the
source based on the monitored temperature.
[0019] In another illustrative embodiment, controlling the flow
rate may include monitoring the flow rate of liquid air from the
source and adjusting the flow rate of the liquid air from the
source based on the monitored flow rate.
[0020] In still another illustrative embodiment, the method may
further include determining if the temperature within the storage
container is within a predetermined temperature range and
generating a flow rate control signal in response thereto.
Illustratively, the method may further include changing the flow
rate of the liquid air from the source in response to the flow rate
control signal.
[0021] According to yet another aspect of the present disclosure, a
liquid air refrigeration system for a thermally-insulated storage
container includes a liquid air refrigeration system, and a liquid
air control system electrically coupled to the liquid air
refrigeration system. The control system includes (i) a processing
unit, and (ii) a memory unit electrically coupled to the processing
unit. Illustratively, the memory unit has a plurality of
instructions stored therein, which, when executed by the processing
unit, causes the processing unit to: (a) operate the liquid air
refrigeration system so as to advance liquid air from a liquid air
storage tank to a thermally-insulated interior of a trailer, (b)
determine if the temperature within the thermally-insulated
interior of the trailer is within a predetermined temperature range
and generating a flow rate signal in response thereto, and (c)
change the flow rate of the liquid air from the liquid air storage
tank to the thermally-insulated interior of the trailer in response
to the flow rate signal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a schematic view of a container including a liquid
air refrigeration system.
DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
[0023] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to a number
of illustrative embodiments shown in the attached drawings and
specific language will be used to describe the same. While the
concepts of this disclosure are described in relation to a mobile
storage container, it will be understood that they are equally
applicable to other storage containers generally, and more
specifically to conventional box or van type trailers, examples of
which include, but should not be limited to, straight truck bodies,
small personal and/or commercial trailers and the like.
[0024] Referring now to FIG. 1, a liquid air refrigeration system
10 is provided for use with a storage container 12. Illustratively,
the storage container 12 may be a static or mobile thermally
insulated container. In particular, the storage container 12 may be
an insulated trailer configured to be coupled with a truck, or
tractor, for storing and transporting various goods therein in a
refrigerated atmosphere. Such a refrigerated trailer may include a
front wall, opposite side walls, a roof, and an end wall including
one or more doors which may collectively cooperate to define a
cargo area for storing refrigerated items therein. The opposite
side walls may be thermally insulated an dmay include inner and
outer aluminum side walls having aluminum posts and foam insulation
therebetween. Alternatively, the side walls of such a trailer may
be formed of an inner fiberglass skin, and outer fiberglass skin,
and a thermoset plastic core, such as that described in U.S. Pat.
No. 6,505,883, for example, the entirety of which is incorporated
by reference herein. While the storage container 12 may be a
trailer or may form a portion of a trailer configured to be coupled
with a tractor, it should be understood that the storage container
may also form a portion of another refrigerated vehicle such as a
van having an insulated storage container, for example.
[0025] Of course, it is within the scope of this disclosure for the
storage container to be any suitable static or mobile thermally
insulated storage container capable of storing goods therein in a
refrigerated, or sub-zero (i.e., below 0.degree. C.), atmosphere.
It should be understood that the liquid air refrigeration system 10
is capable of maintaining a cooled atmosphere within the storage
container 12 at any desired temperature.
[0026] As noted in greater detail below, the liquid air
refrigeration system 10 uses liquid air to cool the interior 14 of
the thermally-insulated portion or compartment of the storage
container 12 to sub-zero, or other desired, temperatures.
Illustratively, the liquid air refrigeration system 12 uses cooled
liquid air in order to refrigerate the interior 14 of the storage
container 12. Illustratively, liquid air is air that has been
compressed and cooled to very low temperatures such that it has
been condensed into a liquid. Liquid air is oftentimes used as a
source of nitrogen, oxygen, argon, and other inert gases. In
particular, liquid air may be fractioned into its constituent
gasses in liquid or gaseous form through an air separation plant.
The production of liquid air is oftentimes used commercially as an
intermediate step in an air separation process, i.e., the
production of nitrogen, oxygen, and argon and other inert gases.
Air separation plants produce the atmospheric industrial gases
nitrogen, oxygen, and argon.
[0027] As noted above, the container 12 is thermally insulated. As
such, the container may include an inner and outer skin (not shown)
forming the top, bottom, end, and/or sidewalls of the
thermally-insulated portion of the container. An insulation layer
(not shown) is provided between the inner and outer skins.
[0028] Illustratively, the liquid air refrigeration system 10
includes a liquid air tank 16 configured to store liquid air
therein. The liquid air tank 16 is thermally-insulated and/or
vacuum-insulated in order to maintain the liquid air therein at a
sufficiently low temperature. In other words, the liquid air tank
16 stores the liquid air under pressure in a thermally insulated
environment. The liquid air tank 16 may include an inlet port 40
configured to receive cooled liquid air therethrough in order to
fill the liquid air tank 16 and an outlet port 42 also configured
to pass liquid air therethrough. Illustratively, the liquid air
tank 16 may include more than one outlet port, such as the second
outlet port 44 schematically shown with the inlet and first outlet
ports 40, 42 in FIG. 1. The liquid air tank 16 may also include
additional outlet ports (not shown). The liquid air tank 16 may be
stored outside the storage container 12 or simply outside the
thermally-insulated portion of the storage container 12. The liquid
air tank 16 may also be coupled to the storage container 12. For
example, the liquid air tank 16 may be mounted below a flooring
system of the storage container 12 and/or may be coupled to one or
more of the side walls of the storage container 12.
[0029] The liquid air tank 16 further includes a valve system 17 to
control the flow of the liquid gas out the exit port(s) 42, 44,
with respect to the demand. In particular, the valve system 17
includes an outlet valve 52 within the outlet port 42, an outlet
valve 54 within the outlet port 44, and an inlet valve 50 within
the inlet port 40. It should be understood, however, that the
liquid air tank 16 may include additional valves as part of the
valve system 17. As is discussed in greater detail below, a control
system 24 of the liquid air refrigeration system 10 is electrically
coupled to the valve system 17 in order to control the opening and
closing of the valves to control the flow of the liquid air from
the tank 16. It should be understood that the term electrically
coupled may refer to wired and wireless electrical connections
between components. Further illustratively, the liquid air
refrigeration system 10 may include additional valves (not shown)
within a conduit system 20 described below, in order to control the
flow of the liquid air from the tank 16 to the interior 14 of the
storage container 10. Illustratively, the control system 24
includes a processing unit 19 and a memory unit 21 electrically
coupled to the processing unit 19. Illustratively, the memory unit
21 has a plurality of instructions stored therein, which, when
executed by the processing unit 19, causes the processing unit 19
to operate various components of the liquid air refrigeration
system 10 so as to advance liquid air from the storage tank 16 to
the interior of the container 12. Power sources for the control
system 24 may include battery, power-hook-up to a motive power
source such as a tractor, power-hook-up to a ground based supply,
or any combination thereof.
[0030] The liquid air tank 16 may also include pressure and/or
temperature sensors 23 and a microcontroller (not shown) for
protecting against excessive pressure build-up in order to ensure
that the liquid air tank 16 is in compliance with various rules,
standards, and regulations governing such devices. Additional
sensor(s) (not shown) may be provided within the tank 16 to monitor
the amount of liquid air within the tank 16. Thus, the control
system 24, being in electrical communication with such sensor(s),
may provide an alert, warning, or other such alarm when the amount
of liquid air with the tank 16 drops below a preset threshold level
to alert the user of the need to refill the tank 16. While only one
liquid air tank 16 is shown, it should be understood that the
liquid air refrigeration system 10 may include any number of liquid
air tanks 16 for storing liquid air therein. Such additional liquid
air tanks 16 may be coupled to the liquid air tank 16 in order to
fill the liquid air tank 16 as it is emptied and/or the additional
liquid air tanks may be coupled directly to an evaporator 18 and/or
in electrical communication with the control system 24. Such
additional liquid air tanks may operate independently of the liquid
air tank 16 or may operate with the liquid air tank 16 such that
multiple liquid air tanks are used simultaneously to cool the
interior 14 of the trailer 12.
[0031] As noted above, the liquid air refrigeration system 10
further includes a conduit system 20 having a first end portion 25
coupled to the outlet port of the tank 16 and a second end portion
27 located within the interior 14 of the thermally-insulated
portion of the storage container 12. Illustratively, as shown in
FIG. 1, a plurality of spray heads 22 are coupled to and depend
downwardly from the second end portion of the conduit 20. While
three spray heads 22 are illustratively shown in FIG. 1, it should
be understood that any suitable number of spray heads 22 may be
used depending on the size and configuration of the storage
container. Further, while the schematic view of the liquid air
refrigeration system shown in FIG. 1 illustrates a single feed line
(i.e., the second end portion 27 of the conduit 20) within the
container 12, it should be understood that any number of
interconnected conduits and subconduits may be provided. In other
words, the conduit system 20 may include an array of pipes and feed
lines within the container 12 in order to evenly distribute the
liquid air throughout the interior 14 of the insulated portion of
the storage container 12. As noted above, the valve system 17 may
include valves (not shown) which are provided throughout the
conduit system 20 and at each spray head 22 in order to control the
flow of the liquid air selectively to one or more spray heads
22.
[0032] As noted above, the control system 24 is in electrical
communication with the liquid air tank 14 and the conduit system
20, as well as with various other components of the system 10
including, but not limited to, the valve system 17 and pressure and
temperature sensors 23 of the tank 16 as well as one or more
temperature sensors 31 mounted within the interior 14 of the
thermally-insulated portion of the container 12, for example.
Illustratively, the temperatures sensors 31 may be provided within
one or more regions of the interior 14 of the storage container 12
in order to detect temperatures of each of these regions. The
temperature sensors 31 may be mounted to the side walls, front
wall, rear wall and doors, and/or the flooring system of the
storage container 12. Illustratively, the control system 24
operates to control and maintain the temperature of the liquid air
tank 16 and to control and maintain the desired output of liquid
air from the tank 16 to the conduit system 20. In particular, the
control system 24 is incorporated to provide modulation of the
liquid air fluid flow in accordance with the demands of pre-set
temperature requirements of the interior 14 of the
thermally-insulated container 12. The fluid flow is also monitored
by the control system 24 through the use of one or more
thermocouples or other flow rate sensors 60 mounted within the
conduit system 20 of the liquid air refrigeration system 10.
Illustratively, the flow rate sensors 60 may be positioned at any
suitable location within the conduit system 20. For example, the
flow rate sensors 60 may be positioned at the first end portion 25
of the conduit system 20 or within the second end portion 27 of the
conduit system 27 within the storage container 12. Further, the
flow rate sensors 60 may also be positioned within or near the
spray heads 22 of the conduit system 20. The control system 24 may
further be programmed to stop fluid flow to the spray heads 22 (by
controlling the valve system 17 of the tank 16, for example) when
access doors (not shown) of the container 12 are opened and remain
in an opened position. The conduit system 20 and/or the spray heads
22 may further include a plurality of valves (not shown) in
electrical communication with the control system 24 for controlling
and regulating fluid flow through the conduit system 20 and into
the container 12. The control system 24 further operates to provide
a system performance monitoring and data logging function. The
control system 24 further operates to provide for alarm outputs in
the event of any system malfunction. For example, the control
system 24 may telemetrically control an audible and/or visible
alarm for alerting users of one or more system malfunctions. The
control system 24 may also include a display screen and input
device to allow an operator to monitor and change system parameters
such as the flow rate of the liquid air from the tank 16 and/or the
desired temperature range within the thermally-insulated interior
14 of the container 12, for example.
[0033] In operation, the control system 24 operates to generate a
gas pressure or flow rate signal through the conduit system 20
responsive to a temperature signal received from one or more
temperature sensors 31 mounted within the container 12. The control
system 24 regulates the gas pressure in the conduit system 20 when
a temperature above or below a preset or predetermined temperature
range is sensed within the container 12. In other words, the
control system 24 operates to determine if the temperature within
the storage container 12 is within the predetermined temperature
range, and then operates to generate a flow rate control signal in
response thereto. As such, the control system 24 operates to adjust
the flow rate of the liquid air from the tank 16 in response to the
flow rate control signal by adjusting the valve system 17 of the
tank 16, As such, the temperature sensors 31 installed in the
interior 14 of the container 12 monitor the temperature within the
container 12 and provide this feedback to the control system 24
such that the control system 24 may control the flow rate of the
liquid air from the tank 16 into the conduit system 20 and thereby
maintain the refrigeration process in control with respect to the
predetermined temperature limits.
[0034] The liquid air refrigeration system 10 may also include an
evaporator tank 18 coupled to the outlet port of the liquid air
tank 16. Illustratively, the evaporator tank 18 is configured to
change the liquid air from a liquid state to a gas state such that
cooled gaseous air 33 is dispensed from the spray heads 22. As
such, the liquid air within the tank 16 may be delivered to the
thermally-insulated portion 14 of the container 12 as a gaseous
spray following passage through the evaporator 18. Alternatively,
when the system 10 does not include an evaporator tank 18, the
liquid air is delivered in a liquid phase thus creating a droplet
spray from the spray heads 22. While the evaporator tank 18 is
shown to be located outside the thermally-insulated interior
portion 14 of the storage container 12, it should be understood
that the evaporator tank 18 may be positioned within the interior
14 of the thermally-insulated portion of the container 12. The
control system 24 is also in electrical communication with the
evaporator tank 18.
[0035] In operation, liquid air from the tank 16 is advanced
through the conduit system 20 to the interior 14 of the insulated
portion of the storage container 12 in order to refrigerate the
interior 14 of the container 12. As shown in FIG. 1, the liquid air
is transported from the liquid air tank 16 through the conduit
system 20 to exit into the interior 14 of the container 12 via the
spray heads 22. The liquid air will emerge from the spray heads 22
as either a droplet spray or as a cold gas 33 (depending on whether
the liquid air passed through an evaporator, such as the evaporator
18, or not) in order to chill the interior 14 of the thermally
insulated container 12. Illustratively, the liquid air
refrigeration system 10 may include one or more heat exchanger
systems (not shown) located within the conduit system 20 at or near
the spray heads 22 to ensure conversion of the fluid liquid air to
a gaseous state prior to emergence from the spray heads 22. Such a
heat exchanger system may include one or more sensors located
within the pipes at or near the spray heads 22 as well as a
microprocessor and controller electrically coupled to the sensors.
Illustratively, the sensors may be electrically coupled to the
control system 24. In the event that one or more sensors senses
liquid air which has not been converted to the gaseous state, the
controller 24 may be programmed to halt operation of the
refrigeration system 10 and to turn off the spray heads 22 to
prevent or minimize any liquid (non gaseous) air from exiting the
spray heads 22 into the interior 14 of the thermally-insulated
container 12.
[0036] Illustratively, the gaseous form of the liquid air is
breathable and, therefore, allows for immediate entry into the
refrigerated area without the need for time consuming gas
evacuation of any non-breathable cryogenic gasses, such as carbon
dioxide or nitrogen, or other non-breathable cryogenic gas
products. The use of such a breathable refrigerant also eliminates
the need for verification of a safe oxygen level within the
interior 14 of the container 12 prior to allowing entry to the
container 12. In other words, the use of liquid air over other zero
oxygen or low oxygen cryogenic liquid gasses is that the atmosphere
within the container 12 will remain breathable and, although cold,
conducive to the support of human life. Thus, oxygen monitoring
systems, vent systems to vent the asphyxiate gasses and/or
breathing apparatuses are not required for the safe use of the
liquid air refrigeration system 10. Further, elimination of the
need to vent asphyxiate gasses may also reduce operating costs due
to mitigation of the need to recharge the container's atmosphere
after personnel ingress and egress.
[0037] While the invention has been illustrated and described in
detail in the foregoing drawings and description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only illustrative embodiments thereof have
been shown and described and that all changes and modifications
that come within the spirit of the invention are desired to be
protected.
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