Note: Descriptions are shown in the official language in which they were submitted.
Attorney Docket No. 047177-9691-US02
HYBRID SHELF WITH EMBEDDED THERMAL SPREADER
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of and priority to U.S.
Provisional Patent
Application No. 63/300,977, filed on January 19, 2022, the entire contents of
which are hereby
incorporated by reference.
BACKGROUND
[0002] The present invention relates to refrigerated merchandisers, and
more particularly to
refrigerated merchandisers including open commercial refrigerated
merchandisers.
[0003] Refrigerated merchandisers are typically used in retail food store
settings such as
grocery stores and convenience stores where fresh food product is displayed in
a refrigerated
environment. In general, refrigerated merchandisers include a case defining a
product display area
for supporting and displaying food products to be visible and accessible
through an access opening
in the case. Some merchandisers include doors to enclose the product display
area and other
refrigerated merchandisers are open to the ambient environment. Open
refrigerated merchandisers
utilize one or more air curtains that flow over the access opening to form a
barrier between the
refrigerated product display area and the ambient environment.
[0004] Refrigerated merchandisers also typically include one or more
shelves that are used to
support and display the food product. The shelves extend generally
horizontally from a rear wall
of the refrigerated merchandiser and are arranged vertically relative to one
another within the
display area. Existing refrigerated merchandisers cool food products on the
shelves from the rear
wall of the merchandiser forward by discharging cooling air from rear wall
apertures. Cooling fans
circulate the cooling air forward.
[0005] A particular challenge of open refrigerated merchandisers is
maintaining a uniform
temperature within the display area. The front of the display is not only
further from the discharged
cooling air but is also exposed to warmer ambient air infiltrating the air
curtain. Therefore, the
front of the display is warmer than the rear of the display. Current methods
for homogenizing the
temperature within the display area include increasing air velocity within the
case and additional
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convection cooling apparatuses. The current solutions, however, require more
energy usage and
have variable efficacy depending on product layout and snowing-up patterns of
the evaporator.
SUMMARY
[0006] In one aspect, the present invention provides a refrigerated
merchandiser including a
case defining a product display area and including an air inlet and an air
outlet in communication
with the product display area to form an air curtain across a front of the
product display area. The
refrigerated merchandiser also includes a shelf that is coupled to the case
within the product display
area. The shelf includes insulation between a top and a bottom of the shelf,
and a passive heat
exchanger that has a heat pipe embedded in the shelf within the insulation and
that extends from a
front of the shelf to a back of the shelf. Ambient air infiltrating the air
curtain initiates passive heat
transfer within the plurality of heat tubes.
[0007] In another aspect, the invention provides a shelf configured to be
attached to a
merchandiser. The shelf includes a top wall, a front wall coupled to the top
wall, side walls coupled
to the front wall and the top wall, and a bottom wall coupled to the front
wall and the sidewalls to
enclose a space between the top wall, the front wall, the side walls, and the
bottom wall. The shelf
also includes insulation disposed in the space and a passive heat exchanger
disposed in the space.
The passive heat exchanger has a heat pipe that is embedded within the
insulation and that extends
from a front of the shelf to a back of the shelf. Passive heat transfer is
configured to be initiated by
ambient air infiltrating the merchandiser.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic cross-section view of a refrigerated
merchandiser embodying the
present invention and illustrating a plurality of shelves.
[0009] FIG. 2 is a schematic perspective view of one of the shelves of FIG.
1 including heat
pipes.
[0010] FIG. 3 is a schematic perspective view of a portion of the shelf of
FIG. 2.
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[0011] FIG. 4 is a front perspective view of the shelf of FIG. 2 supporting
food product and
temperature measurement equipment.
[0012] FIG. 5 is a graph illustrating surface temperatures associated with
the shelf of FIG. 4.
[0013] FIG. 6 is another graph illustrating temperatures associated with
food product
supported by the shelf of FIG. 4.
[0014] FIG. 7 is a chart illustrating surface temperatures of the shelf of
FIG. 4.
[0015] FIGS. 8 is another chart illustrating temperatures food product
supported by the shelf
of FIG. 4.
[0016] FIG. 9 is a section view of an exemplary heat pipe for the shelf of
FIGS. 2-4.
[0017] Before any embodiments of the application are explained in detail,
it is to be understood
that the application is not limited in its application to the details of
construction and the
arrangement of components set forth in the following description or
illustrated in the following
drawings. The application is capable of other embodiments and of being
practiced or of being
carried out in various ways.
DETAILED DESCRIPTION
[0018] FIG. 1 illustrates a refrigerated merchandiser 10 that may be
located in a supermarket
or a convenience store for displaying fresh food product 14 to consumers. The
merchandiser 10
includes a case 18 having a base 22, a rear wall 26, sidewalls (not shown), a
canopy 30, and a
customer access opening 34. The rear wall 26, base 22, sidewalls, and canopy
30 cooperate to
define a partially enclosed product display area 38. The product display area
38 supports the food
product 14 in the case 18. The food product 14 is displayed on a plurality of
shelves 42 within the
product display area 38. Each shelf 42 projects forward from the rear wall 26
and is accessible
through the access opening 34.
[0019] In the embodiment of FIG. 1, the refrigerated merchandiser 10 is an
open-front
merchandiser with access opening 34 exposed to an ambient environment. In
other embodiments,
the access opening 34 may be enclosed by one or more doors (e.g., separated by
mullions). The
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merchandiser 10 includes a refrigeration system 44 (not entirely shown) that
is in communication
with the product display area 38 to provide refrigerated air (denoted by
arrows 48) to the product
display area 38. As shown, the refrigeration system 44 includes an evaporator
52 that is disposed
in an air passageway 56 of the case 18, a compressor (not shown), and a
condenser (not shown)
connected in series. Refrigerated airflow 48 exits the evaporator 52 and is
directed through the air
passageway 56 and is discharged into the display area 38 as an air curtain
that maintains proper
temperature conductions for food product 14 on display.
[0020] The airflow 48 is discharged through the canopy 30 through an air
outlet 60 and is
directed downward through the product display area 38 toward the base 22. At
least a portion of
the airflow 48 is returned to the air passageway 56 of the refrigeration
system 44 via an air inlet
64. As shown in FIG. 1, the airflow 48 is drawn into the air passageway 56 by
a fan 68 upstream
of the evaporator 52. The air inlet 64 is located adjacent a bottom end of the
display area 38 and
the air outlet 60 is located adjacent a top end of the product display area
38.
[0021] With continued reference to FIG. 1, the rear wall 26 includes an
inner panel 72 that at
least partially defines the air passageway 56. The inner panel 72 includes a
plurality of perforations
76 that are in communication with the air passageway 56. The perforations 76
allow a portion of
the airflow 48 to discharge from the air passageway 56 along a rear portion of
the refrigerated
merchandiser 10 and into the product display area 38. In some embodiments, the
perforations 76
include a matrix of circular openings through the inner panel 72. In other
embodiments, the
perforations 76 may be vents that are constructed as elongate (e.g.,
rectangular) openings through
the inner panel 72. It will be appreciated that various other shapes, sizes,
and arrangements for the
perforations 76 are also possible in other embodiments.
[0022] Referring to FIG. 2, each of the shelves 42 includes a top wall 80,
two sidewalls 84,
and a front wall 88. Some or all of the walls 80, 84, 88 may be separate
pieces that are coupled
together, or some or all of the walls 80, 84, 88 may be formed by bending or
shaping a single piece
of material such that edges are defined between the walls (i.e. the walls are
coupled together at the
edge). It will be appreciated that two or more of the walls may be coupled
together by insulation
89. In the illustrated embodiment, the top wall 80, the sidewalls 84, and the
front wall 88 cooperate
to define an interior volume of the shelf 42. In some embodiments, the walls
80, 84, 88 form a
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solid shelf 42 (i.e. filled with insulation 89). With reference to FIGS. 1 and
2, the shelf 42 is
coupled to the rear wall 26 (e.g., via brackets 90) and projects forward
toward the front of the
merchandiser 10. As shown, the top wall 80 projects generally perpendicular
from the inner panel
72 and the sidewalls 84 and the front wall 88 extend substantially
perpendicular to the top wall 80.
In some embodiments, the shelves 42 may include a bottom wall 92.
[0023] With reference to FIGS. 2 and 3, one or more of the shelves 42
includes a passive heat
exchanger 100. The illustrated passive heat exchanger 100 is formed by one or
more thermally
conductive heat pipes 102 (e.g., with a thermal conductivity range between
1,000 and 10,000
W/m K). As shown in FIGS. 2, 3, and 9, each heat pipe 102 is defined by an
elongate tube (e.g., a
cylindrical or rectangular prism) that supports a wick 103 and a working fluid
104, and that has a
first end 106 positioned at or adjacent the front wall 88 and a second end 110
positioned at or
adjacent the inner panel 72. Each heat pipe 102 may be embedded in the shelf
42 and may be
coupled to the interior of the shelf via elongate grooves 114 (e.g., defined
within insulation 89).
The heat pipes 102 can be secured within the elongate grooves 114 by a press-
fit attachment,
soldering or welding, thermal epoxies, or any other suitable attachment
mechanism. It will be
appreciated that the heat pipes 102 may be coupled to an underside of the top
wall 80 without
grooves (e.g., adhered or otherwise attached to the top wall 80, sandwiched
between the top wall
and the bottom wall 92, etc.).
[0024] The heat pipes 102 are metallic and are vacuumed-sealed. As shown in
FIG. 9, the wick
103 defines a capillary lining that may be fixed to the inner walls of the
heat pipe 102 and may
include a metallic material (e.g., sintered copper, screen mesh, grooved
metal, etc.). Other wicking
materials that are suitable for flow of the working fluid 104 through the wick
103 may be used in
combination with or in lieu of metallic material. The first end 106, which is
proximate to the
customer access opening 32 and the front of the shelf 42, defines an
evaporator side of the heat
pipe 102. The second end 110, which is proximate to the inner panel 72 and the
rear of the shelf
42 defines a condenser side of the heat pipe 102.
[0025] Referring to FIG. 2, the passive heat exchanger 100 includes six
linear heat pipes 102
that extend between the rear wall of the shelf 42 and the front wall 88 in a
direction that is
perpendicular to the front wall 88. The illustrated heat pipes 102 also are
parallel to each other. It
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will be appreciated that the shelf 42 may have fewer than six heat pipes or
more than six heat pipes.
The heat pipes 102 form a one- or two-phase heat transfer mechanism to
transfer infiltrating heat
adjacent the front of the shelf 42 toward the rear of the shelf 42. to
maintain more uniform
temperature within the product display area 38, especially in regions adjacent
the heat pipe 102 on
the shelf 42. The passive heat exchanger 100 limits temperature fluctuations
by cooling the portion
of the shelf 42 adjacent the access opening 34 to reduce or eliminate the
warmer region. This
results in a uniform temperature profile across the shelf 42 and a more
consistent overall
temperature within the merchandiser 10.
[0026] The passive heat exchanger 100 can be retrofit into existing
merchandisers (e.g., by
replacing existing shelves with shelves 42 that have the passive heat
exchanger 100. Separately or
in addition, the passive heat exchanger 100 may be integrated into different
parts of the
merchandiser 10 to facilitate even distribution of conditioning air relative
to warm and cold areas
within the merchandiser 10. For example, and with reference to FIG. 1, the
merchandiser may
include a deck plate 134 that partially defines the display area 38 (i.e. a
lower boundary of the
display area 38). The deck plate 134 is positioned above the base 22 and, in
some embodiments, a
passive heat exchanger that is the same as the passive heat exchanger 100 may
be embedded in the
deck plate 134 (e.g., in an insulation-filled cavity in the deck plate 134).
[0027] In operation, refrigerated airflow 48 may be discharged through the
plurality of
perforations 76 and into the display area 38. In some constructions,
conditioned air may only be
distributed to the product display area 38 via the air outlet 60 (e.g., when
the merchandiser 10 does
not include the perforations 76), or in combination with the perforations 76.
Ambient air may
infiltrate the display area 38 through the access opening 34. The ambient air
is generally warmer
than the refrigerated airflow 48 forming the air curtain 48 at the front of
the customer access
opening 34. The ambient air heats the working fluid within the first end 106
of the heat pipe 102.
The working fluid vaporizes on the evaporator side and increases pressure
within the heat pipe
102. As the pressure increases, the vaporized working fluid flows rearward via
the wick toward
the condenser side, proximate the inner panel 72. At the second end 110, the
vaporized working
fluid discharges heat as it is cooled and condensed. The condensed working
fluid travels back
toward the warmer first end 106, evenly distributing a cooling effect within
the display area 38.
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[0028] FIG. 4 illustrates an exemplary refrigerated merchandiser 10 with a
passive heat
exchanger 100 including a heat pipe 102 that is embedded in the shelf 42,
which supports food
product 14. Temperature sensors 118 are coupled to the top wall 80 (e.g., in a
test environment) to
measure temperatures of the shelf 42 in different locations (e.g., over a
section 120 of the shelf
42). For example, and as shown in FIG. 4, one or more sensors 118 are
positioned on the exterior
side of the top wall 80 directly over the heat pipe 102, and other sensors 118
are positioned on the
top wall 80 opposite sides of the heat pipe 102 (e.g., on a side to the left
of the heat pipe 102 and
on a side to the right of the heat pipe 102). The portions of the shelf 102 to
the left and the right of
the heat pipe 102 define left and right test sections of the shelf 42,
respectively, and the portion of
the shelf 102 that is centered over the heat pipe defines a center test
section.
[0029] FIG. 5 graphically illustrates an average temperature profile of an
exemplary shelf 42
that includes the heat pipe 102 when the evaporator 52 has a setpoint of 26
Fahrenheit. FIG. 7
illustrates temperature data provided by the sensors 118 in the left test
section, the center test
section, and the right test section. As shown, the heat pipe 102 maintains a
more uniform surface
temperature on the shelf 42 (at the center) when compared to the left and
right test sections that do
not include a heat pipe. More specifically, and with reference to FIG. 7, the
average temperature
difference or variation on the top wall 80 in the center test section, from
adjacent the front of the
shelf 42 to adjacent the inner panel 72, is approximately 2.1 Fahrenheit,
whereas the average
temperature differences on the top wall 80 in the left test section and the
right test section (from
front-to-back on the top wall 80) are approximately 7.4 and 7.3 Fahrenheit,
respectively. Stated
another way, the heat pipe 102 decreases the temperature variation on the top
wall 80, on average,
from front to back by approximately 70% relative to sections or portions of
the shelf 42 without a
heat pipe. The second chart in FIG. 7 illustrates the temperature profile of
the shelf 42 in the left,
center, and right test sections when the refrigeration system 44 is in a
defrost mode. As will be
appreciated by one of ordinary skill in the art, even during defrost the heat
pipe 102 maintains a
more uniform (e.g., a decrease in temperature variation of approximately 58%)
and lower overall
surface temperature on the shelf 42 relative to the sections to the left and
right of the heat pipe 102.
The third chart in FIG. 7 illustrates the temperature profiles of the left,
center, and right test sections
of the shelf 42 soon after defrost has been terminated (e.g., before frost
buildup in the evaporator
52) and shows that the heat pipe 102 maintains a more uniform temperature
profile from front to
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back on the shelf 42 than in the left and right test sections (e.g., a 70%
decrease in temperature
variation on the top wall 80 from front to back relative to sections or
portions of the shelf 42
without a heat pipe).
[0030] FIGS. 6 and 8 illustrate similar uniformity in the temperature
variation, from front to
back, for food product (tested using food product simulators) that is
supported on the shelf 42 over
the heat pipe 102 and a decrease in temperature variation relative to food
product that is supported
on the shelf 42 to the left and right of the food product supported over the
heat pipe 102. More
specifically, and with reference to FIG. 8, the average temperature difference
or variation for food
product in the center test section, from adjacent the front of the shelf 42 to
adjacent the inner panel
72, is approximately 5.9 Fahrenheit, whereas the average temperature
differences for food product
in the left test section and the right test section (from front-to-back) are
approximately 8.2 and
8.1 Fahrenheit, respectively. Stated another way, the heat pipe 102 decreases
the temperature
variation of food product, on average, from front to back by approximately 27%
relative to food
product on sections or portions of the shelf 42 without a heat pipe. The
second chart in FIG. 8
illustrates the temperature profile of food product in the left, center, and
right test sections when
the refrigeration system 44 is in a defrost mode. Even during defrost, the
heat pipe 102 maintains
a more uniform (e.g., approximately a 25% decrease in temperature variation)
and lower overall
temperature of food product relative to the sections to the left and right of
the heat pipe 102. The
third chart in FIG. 8 illustrates the temperature profiles of food product
supported in the left, center,
and right test sections of the shelf 42 soon after defrost has been terminated
(e.g., before frost
buildup in the evaporator 52) and shows that the heat pipe 102 maintains a
more uniform
temperature profile from front to back on the shelf 42 than in the left and
right test sections (e.g.,
a 27% decrease in temperature variation from front to back relative to food
product in sections or
portions of the shelf 42 without a heat pipe).
[0031] In some embodiments, the top wall 80 be encapsulated by a shelf
cover and may be
formed of a material suitable to spread the cooling impact of the heat pipe
102 (e.g., metal) toward
and at least partially into the sections of the shelf 42 that are adjacent and
to the left or right of the
heat pipe 102. The heat pipe(s) 102 may be embedded in insulation 89 to
facilitate a more
significant and direct impact on the temperature of the shelf 42 and food
product supported on the
shelf 42. Also, by using several heat pipes 102 in a given shelf 42 (and or/
in the deck plate 134),
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the heat pipes 102 can be spaced so that sections of the shelf 42 between the
heat pipes 102 are
minimized to avoid less uniform temperature variations from front to back on
the shelf 42. In
general, the embedded heat pipe 102 makes the cooling effect predictable and
reliable regardless
the layout or loading of product on the shelf 42. Existing systems that use an
evaporator coil in a
shelf cannot achieve the uniformity of temperature, from front to back in the
product display area
38, associated with the invention described herein.
[0032] Various features of the disclosure are set forth in the following
claims.
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