Note: Descriptions are shown in the official language in which they were submitted.
CA 03055338 2019-09-04
PCT/CA2018/000073
4
18 October 2018 18-10-2018
274848.00076/92729764.1
PASSIVE REFRIGERATION SYSTEM FOR THE COLD CHAIN INDUSTRY
FIELD OF THE INVENTION
[001] The present invention relates to the field of passive refrigeration
systems, for use in
refrigerating perishable products during shipping and storage. More
specifically, the present
invention is directed to a refrigeration system that uses carbon-dioxide-free
cooling in the load
chamber, and which has a high degree of temperature regulation. The system
may, for example,
be used for pallet-sized loads, for trailer-sized loads and for stationary
cold storage facilities, and
is therefore scalable.
BACKGROUND
[002] The cold chain industry is responsible for shipping and storing
refrigerated temperature-
sensitive products, such as food and pharmaceuticals. Losses can be incurred
because of
insufficient refrigeration or improper temperatures. Currently, companies
involved in shipping
perishable foods must either have expensive electro-mechanical refrigeration
trucks with
multiple refrigerated compartments that can be set to different temperatures,
or place all items at
a single temperature and hope the frozen product does not melt and spoil
before delivery.
[003] United States Patent No. 4,891,954 discloses a refrigeration system (10)
consisting of an
insulated railcar (12) that utilizes sublimated carbon dioxide (CO2) to
maintain the integrity of
stored products. The insulated railcar (12) includes a divider (22) that
partitions the insulated
railcar (12) into a lower storage area (26) and an upper bunker (24). The
bunker (24) contains a
distribution manifold (28) for forming carbon dioxide snow and distributing
the formed snow
throughout the bunker (24). Sublimation ports (30) along each sidewall (18)
and end wall (20)
allow the sublimated carbon dioxide to pass to the lower storage area (26) to
refrigerate the
stored products during transit. A plenum (42) and emission vent (44) is
provided at each end of
the insulated railcar (12) to vent sublimated carbon dioxide to the exterior
atmosphere. The
insulated railcar (12) also includes pressure relief ports (32) located
substantially below the
distribution manifold (28) to vent flash gas generated during the snow forming
process. This
technology does not allow for temperature control over time, nor is there a
consistent
temperature throughout the chamber. Further, CO2 is added to the load chamber.
AMENDED SHEET
CA 03055338 2019-09-04
PCT/CA2018/000073
18 October 2018 18-10-2018
274848.00076/92729764.1
- 2 -
[004] United States Patent No. 5,460,013 discloses a refrigerated, thin-walled
shipping
container (8) including a horizontal dividing element (20) forming a
compartment (22) for
holding CO2 snow created by passing liquid CO2 through manifold (24) along at
least one side of
the compartment and spraying the CO2 snow against the opposite wall. The
charging of the
cooling compartment generates gas pressure, and the combination design of the
charging
manifold and pressure release vents allows the operation to be performed
without excessive
structural damaging pressure buildup. This technology does not allow for
temperature control
over time, or in different regions of the container. Further, gaseous CO2 is
added to the chamber.
[005] United States Patent No. 7,310,967 discloses a cryogenic shipping and
storage container,
with an on-board cooling unit in the form of a bunker for holding solid
refrigerant. The unit can
be configured for different sizes, and is used to refrigerate rather than
freeze product. While this
system allows for better temperature control in the chamber, it requires power
and fans, and
therefore is not a passive system. Further, gaseous CO2 is added to the
chamber.
[006] United States Patent No. 8,191,380 discloses a portable active cryo
container, for
maintaining product at refrigerated and/or cryogenic temperatures. The
container comprises a
control system to monitor and control the flow of cooling air from a bunker
section to at least
one material storage section wherein temperature sensitive product is
contained. The control
system is coupled to a fan which enhances heat transfer through forced
convection when the
system moves outside thermal tolerance. The cryo container is powered using
battery packs or
by being plugged into a vehicle's 12-volt power supply. While this system
allows for better
temperature control in the chamber, it requires power and fans, and therefore
is not a passive
system. Further, gaseous CO2 is added to the chamber. The coolant, which is
liquid nitrogen,
travels through a liquid vaporizing heat exchanger. Unlike a heat pipe, it has
an open end. The
open end discharges the coolant into the ambient environment in the chamber.
[007] United States Patent No. 3,714,793 discloses a liquefied gas vaporizer
in the bottom
portion of the freeze-sensitive product storage chamber with thermal
insulation around the liquid
vaporizing conduit and thermally conductive metal floor means contiguously
associated with and
in heat transfer relation to the thermal insulation. The coolant, which is
liquid nitrogen, travels
AMENDED SHEET
CA 03055338 2019-09-04
PCT/CA2018/000073
18 October 2018 18-10-2018
2741348.00076/92729764.1
- 3 -
through a liquid vaporizing heat exchanger. Unlike a heat pipe, it has an open
end. The open
end discharges the coolant into the ambient environment in the chamber.
[008] United States Patent No. 3,421,336 discloses a system for more uniform
distribution of
refrigerant in long-haul trailers and railcars by intermittently spraying cold
fluid into the product
chamber and continuously expanding vaporised cold liquid into the same chamber
with the
production of external work which is recovered to circulate the sprayed cold
fluid.
[009] United States Patent No. 7,891,575 discloses a thermal storage and
transfer system that
includes a cooling system and method using ice or other frozen material with
heat pipes to
produce a cool airstream. Preferably, the ice is disposed in a container with
the condensers and
evaporators of the heat pipes respectively inside and outside the container. A
fan blows air
across the evaporator sections through a duct to circulate within an enclosed
airspace to be
cooled. A separate refrigeration system which may be used to independently
cool the airspace
also freezes water or another liquid to produce the ice or other frozen
material in the container.
The cooling system is broadly applicable, including for use on motor vehicles
to provide cooling
for several hours when the vehicle engine is off. A heating system includes an
adsorbent heat
exchanger for extracting heat from exhaust gases of an engine and heating an
enclosed airspace.
Again, this is not a passive system, since it requires fans.
[010] United States Patent Application Publication No. US2004/0226309
discloses a portable,
temperature-controlled container for storing and transporting temperature-
sensitive materials.
The portable, temperature-controlled container includes a container having a
bottom wall, four
side walls, and a top wall defining a cargo space. The container includes a
temperature
regulating unit connected to the container. The temperature regulating unit
comprises a
refrigeration unit. The temperature regulating unit is in communication with
the cargo space of
the container. The container includes a temperature controller connected to
the container. The
temperature controller comprises a temperature control unit and a temperature
sensor positioned
in the cargo space of the container. The container also includes a power
supply. The
temperature regulating unit can include a heating unit. Again, this is not a
passive refrigeration
system.
AMEND= SET
CA 03055338 2019-09-04
PCT/CA2018/000073
18 October 2018 18-10-2018
274848.00076191719164,1
- 4 -
[011] United States Patent No. 8,162,542 discloses a cargo container that
includes a cargo box
affixed atop a hollow base, with the base including forklift tunnels extending
therethrough with
elongate bays disposed parallel thereto. Each bay includes a removable tray
for receiving
electrical batteries. And, a temperature control system is disposed on a
sidewall adjoining the
base. The cargo container has both an electrical heater and vapor compression
refrigeration.
Onboard batteries provide power during shipping. This is not a passive system.
[012] United States Patent Application Publication No. US2013/0008188
discloses a cryogen
heat exchanger that includes a container having a sidewall defining a chamber
in the container
for containing a cryogen, and at least one heat exchange assembly having a
first portion disposed
in the chamber and extending through the sidewall to a second portion disposed
in an atmosphere
of a space external to the chamber and at an opposite side of the sidewall for
providing heat
transfer to the atmosphere. The system uses heat pipes, but also includes at
least one fan, and
therefore is not a passive system. Temperature can be adjusted by varying the
pressure of the
cryogen (liquid nitrogen or liquid carbon dioxide) in the tank, presumably
with a pump or
.. adjusting fan speed. Again, neither of these methods are passive. Other
methods of adjusting
temperature do not allow for temperature adjustment on the fly, but rather
involve use of a
variable volume liquid reservoir to the evaporator section of each heat pipe.
The heat pipes are
stainless steel or copper.
[013] A refrigerated container that can hold a pallet of product would be
useful for both
shipping and storage of perishable products. It would be preferably if carbon
dioxide or other
coolant was not added to the storage compartment (also sometimes referred to
herein as the "load
chamber"), either directly or indirectly. Carbon dioxide displaces oxygen and
in high
concentrations can asphyxiate a person. Discharging carbon dioxide vapour
directly into the
load space compromises temperature control and because of its very rapid
temperature pulldown,
.. compromises the load unit's structural elements. Further, the expansion
effect caused by phase
change requires significant volumes of the cryogen vapour to vent the
atmosphere, which
increases operating costs by increasing the amount cryogen needed. It would be
more preferable
if it had a passive heat transfer system with no requirement for forced
convection. It would be of
further advantage if the system allowed for delivery and storage of cargo at
various selected and
controlled temperatures.
AMENDED SHEET
CA 03055338 2019-09-04
IcT/CA2018/000073
18 October 2018 18-10-2018
274848.00076/92729764.1
- 5 -
SUMMARY OF THE INVENTION
[014] Disclosed herein is a refrigerated system and container for shipping and
storage of
perishable products. In one embodiment, the refrigerated container is sized to
hold a pallet of
product. Carbon dioxide is not added or released to the storage compartment,
either directly or
indirectly. The system has a passive heat transfer system with no requirement
for forced
convection. The system can be configured to allow for delivery and storage of
cargo at various
selected and controlled temperatures.
[015] In one embodiment, a passive refrigeration box for controlled
refrigeration of a product is
provided, the refrigeration box comprising: an outer box, the outer box
including an outer
insulation layer; an inner box, the inner box including an inner insulation
layer, and a thermal
shield on an outside of the inner insulation layer, the inner box and the
outer box defining a
vapour channel therebetween; and a thermal link, the thermal link including a
thermal layer and a
plurality of heat pipes or thermosyphons, the thermal layer and a top section
of the inner box
defining a coolant chamber, the coolant chamber including a coolant chamber
access, and the
coolant chamber in communication with the vapour channel, and the thermal
layer and a bottom
section of the inner box defining a load chamber, the load chamber including a
load chamber
access, each heat pipe or thermosyphon having a condenser section disposed in
the coolant
chamber and an evaporator section disposed in the load chamber and extending
through the
thermal layer.
[016] The passive refrigeration box may further comprise a mesh header below
the heat pipes
or thermosyphons. The passive refrigeration box may further comprise an outer
skin on the outer
insulation layer and an inner liner on the inner insulation layer. In the
passive refrigeration box,
the thermal shield may be an aluminum shield. In the passive refrigeration
box, the coolant
chamber access may include an outer lid and an inner lid. In the passive
refrigeration box, the
inner lid may be seated on a step in the inner box. The passive refrigeration
box may further
comprise a gasket between the inner lid and the step. In the passive
refrigeration box, the heat
pipes may be weld-free heat pipes.
[017] In the passive refrigeration box, the heat pipes may include a working
fluid, the working
fluid being one of pentane, propylene, acetone and methanol. In the passive
refrigeration box,
AMENDED SHEET
CA 03055338 2019-09-04
PCT/CA2018/000073
=
= 18 October 2018 18-10-2018
274848.00076/92729764.1
- 6 -
the thermal link may be a reconfigurable thermal link. The passive
refrigeration box may further
comprise a check valve in the outer lid.
[018] Also disclosed herein, is a passive refrigeration system for the cold-
chain industry, the
system including a box and a solid coolant, the box comprising: an outer box,
the outer box
including an outer insulation layer; an inner box, the inner box including an
inner insulation
layer, and a thermal shield on an outside of the inner insulation layer, the
inner box and the outer
box defining a vapour channel there between; and a thermal link, the thermal
link including a
thermal layer and a plurality of heat pipes or a plurality of thennosyphons,
the thermal layer and
a top of the inner box defining a coolant chamber, the coolant chamber
including a coolant
.. chamber access, and the coolant chamber in communication with the vapour
channel, and the
thermal layer and a bottom of the inner box defining a load chamber, the load
chamber including
a load chamber access, each heat pipe or thermosyphon having a condenser
section disposed in
the coolant chamber and an evaporator section disposed in the load chamber and
extending
through the thermal layer, and the solid coolant is solid carbon dioxide.
[019] In the system, the thermal link may be a reconfigurable thermal link. In
the system, the
thermal link comprises a plurality of heat pipes. In the system, the heat
pipes may be weld-free
heat pipes. In the system, the heat pipes may include a working fluid, the
working fluid being
one of pentane, propylene, acetone and methanol. In the system, the thermal
shield may be an
aluminum shield.
[020] Also disclosed herein, is a passive refrigeration box for controlled
refrigeration of a
product, the refrigeration box comprising: a bottom, four sides attached to
the bottom, an inner
lid and an outer lid, the sides including an outer insulation layer and an
inner insulation layer, the
layers and the inner and outer lids defining a vapour channel there between,
an aluminum shield
adjacent the vapour channel and abutting an outer side of the inner insulation
layer and a top of
the inner lid, a thermal layer, the thermal layer disposed below the inner lid
and between the
inner insulation layers to define a coolant chamber, the coolant chamber for
retaining a coolant, a
load chamber, the load chamber defined by the inner insulation, and the
thermal layer, and a
plurality of heat pipes or a plurality of thenmosyphons, each heat pipe or
thermosyphon having a
AMENDED SHEET
CA 03055338 2019-09-04
PCT/CA2018/000073
= 18 October 2018 18-10-2018
274848.00076/92729764.1
- 7 -
condenser section disposed in the coolant chamber and an evaporator section
disposed in the load
chamber and extending through the thermal layer.
[021] Also disclosed herein, is a method of refrigerating a load passively,
using the
refrigeration box described above, the method comprising loading the load into
the load chamber
and charging the coolant chamber with a solid coolant.
[022] The method may further comprise configuring the thermal link to regulate
the
temperature of the load. In the method, the solid coolant may be solid carbon
dioxide (or "dry
ice").
BRIEF DESCRIPTION OF THE DRAWINGS
[023] Embodiments of the present invention are described below with reference
to the
accompanying drawings in which:
[024] Figure 1 is a longitudinal sectional view of a heat pipe in accordance
with an aspect of
the present invention.
[025] Figure 2 is a longitudinal sectional view of an end cap and tube end of
the heat pipe of
Figure 1.
[026] Figure 3 is a perspective sectional view of the passive refrigeration
box in accordance
with an aspect of the present invention.
[027] Figure 4 is a longitudinal sectional view of passive refrigeration box
of Figure 3.
[028] Figure 5 is a longitudinal sectional view an alternative embodiment of a
passive
refrigeration box.
[029] Figure 6 is a longitudinal sectional view of an alternative embodiment
of a passive
refrigeration box.
[030] Figure 7A illustrates the operation of a reconfigurable thermal link in
accordance with an
aspect of the present invention.
AMENDED SHEET
CA 03055338 2019-09-04
PCT/CA2018/000073
=
=
= 18 October 2018 18-10-2018
274849.00076/92729764A
- 8 -
[031] Figure 7B illustrates the operation of a reconfigurable thermal link in
accordance with an
aspect of the present invention.
DESCRIPTION
[032] The present invention now will be described more fully hereinafter with
reference to the
accompanying drawing(s), which form a part hereof, and which show, by way of
illustration,
exemplary embodiments by which the invention may be practiced. The invention
may,
however, be embodied in many different forms and should not be construed as
limited to the
embodiments set forth herein; rather, these embodiments are provided so that
this disclosure will
be thorough and complete, and will fully convey the scope of the invention to
those skilled in the
art. The following detailed description is, therefore, not to be taken in a
limiting sense.
[033] lExcept as otherwise expressly provided, the following rules of
interpretation apply to this
specification (written description, claims and drawings): (a) all words used
herein shall be
construed to be of such gender or number (singular or plural) as the
circumstances require; (b)
the singular terms "a", "an", and "the", as used in the specification and the
appended claims
include plural references unless the context clearly dictates otherwise; (c)
the antecedent term
"about" applied to a recited range or value denotes an approximation within
the deviation in the
range or value known or expected in the art from the measurements method; (d)
the words
"herein", "hereby", "hereof', "hereto"," herein before", and "hereinafter",
and words of similar
import, refer to this specification in its entirety and not to any particular
paragraph, claim or
other subdivision, unless otherwise specified; (e) descriptive headings are
for convenience only
and shall not control or affect the meaning or construction of any part of the
specification; and (f)
"or" and "any" are not exclusive and "include" and "including" are not
limiting. Further, the
terms "comprising," "having," "including," and "containing" are to be
construed as open-ended
terms (i.e., meaning "including, but not limited to,") unless otherwise noted.
[034] , To the extent necessary to provide descriptive support, the subject
matter and/or text of
the appended claims is incorporated herein by reference in their entirety.
[035] Recitation of ranges of values herein are merely intended to serve as a
shorthand method
of referring individually to each separate value falling within the range,
unless otherwise
AMENDED SHEET
CA 03055338 2019-09-04
PCT/C.A2018/000073
18 October 2018 18-10-2018
274848.00076/92729764.1
- 9 -
indicated herein, and each separate value is incorporated into the
specification as if it were
individually recited herein. Where a specific range of values is provided, it
is understood that
each intervening value, to the tenth of the unit of the lower limit unless the
context clearly
dictates otherwise, between the upper and lower limit of that range and any
other stated or
intervening value in that stated range, is included therein. All smaller sub
ranges are also
included. The upper and lower limits of these smaller ranges are also included
therein, subject to
any specifically excluded limit in the stated range.
[036] Unless defined otherwise, all technical and scientific terms used herein
have the same
meaning as commonly understood by one of ordinary skill in the relevant art.
Although any
methods and materials similar or equivalent to those described herein can also
be used, the
acceptable methods and materials are now described.
DEFINITIONS
[037] Heat pipe ¨ in the context of the present invention, a heat pipe
consists of a sealed pipe
that un-releasably retains a working fluid. A wick is present in the bore of
the pipe. (In essence,
a heat pipe is a heat-transfer device that combines the principles of both
thermal conductivity and
phase transition to effectively transfer heat between two solid interfaces. At
the hot interface of
a heat pipe a liquid in contact with a thermally conductive solid surface
turns into a vapor by
absorbing heat from that surface. The vapor then travels along the heat pipe
to the cold interface
and condenses back into a liquid ¨ releasing the latent heat. The liquid then
returns to the hot
interface through capillary action (wicking), and the cycle repeats. Due to
the very high heat
transfer coefficients for boiling and condensation, heat pipes are generally
highly effective as
heat transfer devices.)
[038] Thermosyphon ¨ in the context of the present invention, a thermosyphon
is similar in
components and construction to a heat pipe, except it contains a larger amount
of working fluid
and it does not contain a wick structure. It unreleasably retains a working
fluid.
[039] Weld-free heat pipe ¨ in the context of the present invention, a weld-
free heat pipe is one
that has barbed end caps and barbs on the inside of the tube of the heat pipe
proximate the ends.
The end caps and tube are press fit together.
AMENDED SHEET
CA 03055338 2019-09-04
PCT/CA2018/000073
= 18 October 2018 18-10-2018
274848.00076/92729764.1
- 10 -
[040] Weld-free, soldered heat pipe ¨ in the context of the present invention,
a copper heat pipe
is soldered to close the end caps to the tube.
[041] Weld-free, soldered thennosyphon ¨ in the context of the present
invention, a
thermosyphon is soldered to close the end caps to the tube.
[042] Working fluid ¨ in the context of the present invention, a working fluid
is one that is
present as both a saturated liquid phase and a vapour phase in the heat pipe.
The liquid is
evaporated to a vapour at the evaporator region of the heat pipe, and the
vapour is condensed to a
liquid at the condenser region of the heat pipe. For present purposes, any one
of pentane,
propylene, acetone and methanol, are good candidates for use as the working
fluid; other
refrigerants that are also suitable for use as the working fluid will be
apparent to a person skilled
in the art.
[043] Wick ¨ in the context of the present invention, a wick is a material
that lines the bore of
the heat pipe and exerts a capillary action on the liquid phase of the working
fluid.
[044] Thermal link ¨ in the context of the present invention, a thermal link
is an interface for
the management of heat flow (thermal energy flow). The design and the material
used determine
the thermal conduction of the thermal linkage. The thermal linkage includes
the heat pipes and
an insulating or conducting layer (the thermal layer).
[045] Reconfigurable thermal link ¨ in the context of the present invention, a
reconfigurable
thermal link refers to a thermal link that can be altered to change or
optimize the thermal
conductivity for a given application (temperature requirement).
[046] Solid coolant ¨ in the context of the present invention, charging the
coolant chamber with
a solid coolant means that a solid coolant is added, or a liquid coolant is
injected which then
changes phase from a liquid to a solid coolant.
DETAILED DESCRIPTION OF THE INVENTION
[047] A heat pipe, generally referred to as 8 is shown in Figure 1. It is a
tube 10 that has a first
end 12, with a first end cap 14, and a second end 16, with a second end cap
18. The second end
AMENDED SHEET
CA 03055338 2019-09-04
2CT/CA2018/000073
18 October 2018 18-1.0-201.8
274848 00076/92729764 I
- 1 1 -
cap 18 has a fill tube 20 extending therefrom. A bore 22 extends from the
first end cap 14 to the
second end cap 18. The fill tube 20 has a crimping end 24 distal to the second
end cap 18 and a
fill tube bore 26. The second end cap 18 has a central aperture 28. The wall
30 of the central
aperture 28 has a step 32 upon which the proximal end 32 of the fill tube 20
is seated (as may be
more clearly seen in Figure 2). A solder bead 34 attaches the fill tube 20 to
the second end cap
18. In Figure 1, the crimping end 24 is crimped, after the working fluid has
been added to the
pipe. A bead of solder 40 seals the crimped end 24. The heat pipe 8 has a wick
42 in the bore
22.
[048] As shown in Figure 2, and using the second end cap as an example, the
first end 12 and
the second end 16 and the end caps 14, 18 are barbed 50, with the end cap 14,
18 preferably
being the male mating member 52 and the ends 12, 16 being the female mating
member 54 and
also having barbs 56. An 0-ring 60 is seated in the mating pair. This provides
a weld-free heat
[049] As noted above, the heat pipe or thennosyphon (as the case may be), may
be weld-free
and soldered closed.
[050] A passive refrigeration box, generally referred to as 80 is shown in
Figure 3. The
refrigeration box 80 provides passive cooling through the use of heat pipes 8
(for ease of
illustration, only a single row of heat pipes is shown in Figure 3, although
it should be
understood that additional rows of heat pipes or an array of heat pipes would
preferably be used)
and with no release of coolant into the load chamber 82. The outer box 81
includes a bottom 84
attached to four walls 86, and an outer lid 88. The box is preferably
constructed to provide
sufficient strength and support for the load and to be moved using a fork
lift. An outer skin 90 of
aluminum or steel or plastic is optionally supported by a metal frame 92 in
the bottom 84 and
four walls 86. A layer of outer insulation 94 lines the inside 96 of the skin
90 and frame 92. The
outer insulation 94 is preferably closed cell, extruded or expanded
polystyrene or the like and
may include vacuum insulated panel insulation. The bottom 84 includes slots 97
for accepting
forks of a forklift.
Atelf.NDZD SHUT
CA 03055338 2019-09-04
PCT/CA2018/000073
18 October 2018 18-10-2018
274848.00076/92729764.1
- 12 -
[051] An inner box 98 includes four inner walls 100, an inner bottom 102, and
an inner lid 104.
A layer of inner insulation 110 lines the inner liner 112 of the walls 100 and
the skin 114 of the
inner lid 104. The inner insulation 110 is preferably closed cell, extruded or
expanded
polystyrene or the like (including vacuum insulated panel insulation). The
inner liner 112 and
skin 114 are aluminum or plastic. The inner liner 112 includes stand-offs 116
that extend a short
distance into the load chamber 150 to ensure that an air gap is maintained
between the inner liner
112 and the load. The outer lid 88 is preferably similarly constructed of a
skin which is
aluminum or plastic, and provided with insulation that is preferably closed
cell, extruded or
expanded polystyrene or the like (including vacuum insulated panel
insulation).
[052] Abutting the upper surface 118 of the insulation 110 of the inner lid
104 and the outer
surface 120 of the inner insulation 100 is a thermal shield 122 which in the
preferred
embodiment is an aluminum shield 122. The aluminum shield 122 and both the
layer of outer
insulation 94 on the walls 86 and the outer lid 88 define a space referred to
as vapour channel
124. The thermal shield 122 helps to manage heat leaks and maintain the
temperature of the cold
space. It also decreases the time to cool a load from its initial higher
temperature to steady-state
while consuming less solid coolant / dry-ice.
[053] As shown in Figure 4, the inner lid 104 sits on a step 126 in the inner
liner 112. A gasket
128 fits between the inner lid 104 and the step 126 in the inner liner 112.
The vapour channel
124 may be sealed from the ambient environment and, optionally, from the
coolant chamber 140.
Although not expressly shown in Figure 3, in one embodiment, the vapour
channel 124 can be in
communication with the coolant chamber 140, such that the vapour channel 124
also serves to
circulate the sublimated or evaporated coolant from the coolant chamber 140;
in this fashion, the
cold sublimated or evaporated (as the case maybe, depending on the coolant
used) vapour of the
coolant may also be used to help cool the load chamber. Also optionally, a
check valve 125
mounted in the outer lid 88 may be provided, so that a small over pressure can
be maintained
inside the vapour channel 124. This prevents the ingress of external moist air
when the coolant /
dry ice charge is depleted. Further, the check valve 125 can also serve to
prevent the build-up of
excess coolant (evaporated or sublimated) in the vapour channel 124. As such,
the check valve
125 may simply be a one-directional valve, i.e. which allows vapour to be
vented outside to the
ambient environment, but prevents air from the ambient environment from
entering the vapour
AMEND= SHUT
CA 03055338 2019-09-04
PCT/CA2018/000073
18 Octdber 2018 18-10-2018
274848.00076/92729764.1
- 13 -
channel 124. A coolant 142, which is preferably solid carbon dioxide, is
loaded and retained in
the coolant chamber 140. Once closed, the coolant chamber 140 does not
communicate with the
ambient environment. The coolant chamber 140 has a plurality of heat pipes 8
extending into the
load chamber 150 through a base 143 of the coolant chamber 140. The base 143
and the heat
pipes 8 form a reconfigurable thermal link 144. The reconfigurable thermal
link 144 (as
described in further detail below) may also allow for customization and
optimization of thermal
energy transfer between the coolant 142 in the coolant chamber 140 and the
load chamber 150.
The coolant chamber 140 is in a top section 146 of the inner box 98. The load
chamber 150 is in
a bottom section 148 of the inner box 98.
[054] The construction of the heat pipes 8 assist in providing this
customization. The portion of
the heat pipes 8 extending into the coolant chamber 140 includes the condenser
section 152.
Below the base 143 and the inner liner 112 is the load chamber 150. The
portion of the heat
pipes 8 extending into the load chamber 150 includes the evaporator section
156. A mesh header
160 protects the heat pipes 8 from damage in case the load in the load chamber
150 shifts. The
mesh may be made from aluminum, steel or plastic and additionally functions to
ensure
sufficient space for air circulation. The mesh header 160 extends across the
load chamber 150 in
the vicinity of the top 162 of the load chamber 150. The load chamber 150 is
an enclosed space.
[055] An inner door 170 and an outer door 172 may be constructed in the same
manner and
with the same materials as the lids 88, 104. These doors do not impede the
vapour channel 124.
At least one temperature sensor 176 may be located in the load chamber 150 and
is in electronic
communication with a display 178 that is remote to the refrigerator box 80 or
is on an outer
surface 178 of the refrigerator box 80.
[056] In one embodiment, the refrigeration box 80 is sized to accept a pallet
load of product.
The load is placed in the refrigeration box and then the refrigeration box can
be moved into and
out of a storage facility or a truck for transport. Different refrigeration
boxes operating at
different temperatures can be placed side by side and can be delivered
together or independently
of other refrigeration boxes in the truck. This increases the flexibility in
the truck load to be
delivered, allows for optimization of storage conditions for product, and
reduces energy
consumption and the associated pollution caused by running a generator to cool
a truck load.
Amara= SHEZT
CA 03055338 2019-09-04
PCT/CA2018/000073
=
= 18 October 2018 18-10-2018
274848.00076/92719764.1
- 14 -
[057] In an alternative embodiment, a side access allows the coolant chamber
140 either to be
slid out and charged/recharged with solid coolant 142, or simply accessed on
the side and
charged.
[058] In another embodiment, shown in Figure 5, the passive refrigeration box
80 of Figures 3
and 4 further includes a liquid injection port 180 and a distribution manifold
182 in the coolant
chamber 140 for the addition of liquid carbon dioxide. This liquid carbon
dioxide flashes into
solid carbon dioxide snow (solid coolant 142), hence charging the coolant
chamber with solid
coolant 142. In an embodiment, such a charging supply of liquid carbon dioxide
may be
provided/stored with the passive refrigeration box 80 for ready convenience.
[059] In another embodiment, shown in Figure 6, the refrigeration box is sized
to fit as a single
unit in an ISO container 200, hence it is slightly smaller than the inside
dimensions of an ISO
container 200. The load chamber 150 has a load chamber access 202 that may
comprise an inner
door 204 and an outer door 206. The coolant chamber access 208 may be through
lids or an
access 208 on the side, as shown in Figure 6. The construction and
relationship between the
doors is the same as the lids ¨ there is a thermal shield 206 on the outer
side 208 of the inner
door 202 and the vapour channel 210 has an unimpeded path between the doors
202, 204.
[060] In another embodiment, the refrigeration box is a container for
transport on a trailer or a
flat bed. It again may be configured with doors and is as described and shown
in Figure 6.
[061] In another embodiment, the refrigeration box 80 is a trailer. It again
may be configured
with doors and is as described and shown in Figure 6.
[062] In yet another embodiment, the heat pipes in the refrigeration box or
system are replaced
with thermosyphons.
[063] One embodiment of a reconfigurable thermal link (mentioned above as 144)
is illustrated
in Figures 7A and 78 (and generally referenced therein as 249). The function
of the
reconfigurable thermal link 249 is to modulate the thermal resistance along a
specific thermal
conductive pathway joining a relatively warm region to a relatively cooler
region. By physically
adjusting the internal element(s) of the reconfigurable thermal link, the
thermal resistance of the
AMENDED SHEET
CA 03055338 2019-09-04
PCT/CA2018/000073
18 October 2018 18-10-2018
274848.00076/92729764.1
- 15 -
aforementioned thermally conductive path can be altered to affect a change in
the rate at which
heat energy is transferred from the relatively warm region to the relatively
cooler region.
[064] When the reconfigurable thermal link 249 is placed in the thermal path
between the load
chamber 150 (relatively warm region) and the coolant chamber 140 (relatively
cooler region), the
rate of heat transfer may be modulated to the point that some degree of load
chamber
temperature control can be achieved. In one embodiment, the reconfigurable
thermal link 249
can be placed at the condenser end of the heat pipes or therrnosyphon
arrangement (relatively
warm region) and the far colder coolant chamber 140, to affect control over
the heat transfer rate
achieved between the relatively warmer region and the relatively cooler
region.
[065] Figure 7A shows a relatively warmer region 250, a relatively cooler
region 251 and a heat
transfer path 252. The reconfigurable thermal link is made up of a thermally
conductive housing
253 that is divided into two parts by a thermally insulating housing barrier
254. Together the
thermally conductive housing elements 253 and the thermally insulating housing
barrier 254,
make up the entire housing 258. Inside the housing 258 there is a cavity 255
that is partially
occupied by a moving element 259. A portion of the moving element 259 is made
up of a
thermally conductive end 256 and a thermally insulating end 257. The moving
element 259 is
capable of be moved the entire width of the internal cavity 255.
[066] Figure 7A shows the moving element 259 in an internal position whereby
the thermally
resistive path from the relatively warm location 250 to the relatively cooler
location 251 is
minimized. Heat travels through the thermally conductive housing 253, through
the thermally
conductive portion of the internal moving element 256, through the thermally
conductive
housing 253 and finally out to the relatively cooler region beyond 251. At
each stage of this
thermal path, heat is allowed to travel through thermally conductive
materials, thus making the
total thermal resistance of this path low.
[067] Figure 7B shows a perspective view of the reconfigurable thermal link
249 with the
internal moving element 259 shined in such a way as to produce a large thermal
resistance
impeding heat transfer from relatively warm location 250 to relatively cooler
location 251. In
this configuration, the pathway for heat to transfer is substantially blocked
by the dual insulating
AMENDED SHEET
CA 03055338 2019-09-04
PCT/CA2018/000073
= 18 October 2018 18-10-2018
274848.00076/92729764.1
- 16 -
materials present in the internal moving element 257 and the housing insulated
segment 254.
The thermal resistance of both potential heat transfer pathways is very high
as a result of the
thermal insulating materials that now occupy the potential heat transfer
path(s) 252.
[068] The movable internal thermal element 259 can be motivated to change
position by a
.. number of means. Some of these means are passive in that they use no
electrical energy to
operate, while other motivating mechanisms may use non-passive methods.
[069] While example embodiments have been described in connection with what is
presently
considered to be an example of a possible most practical and/or suitable
embodiment, it is to be
understood that the descriptions are not to be limited to the disclosed
embodiments, but on the
.. contrary, is intended to cover various modifications and equivalent
arrangements included within
the spirit and scope of the example embodiment. Those skilled in the art will
recognize, or be
able to ascertain using no more than routine experimentation, many equivalents
to the specific
example embodiments specifically described herein. Such equivalents are
intended to be
encompassed in the scope of the claims, if appended hereto or subsequently
filed.
AMENDED SHEET
