U.S. patent application number 11/455968 was filed with the patent office on 2007-12-20 for refrigerated case with low frost operation.
This patent application is currently assigned to Delaware Capital Formation, Inc.. Invention is credited to Larry C. Howington, Timothy Dean Swofford.
Application Number | 20070289323 11/455968 |
Document ID | / |
Family ID | 38860259 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070289323 |
Kind Code |
A1 |
Swofford; Timothy Dean ; et
al. |
December 20, 2007 |
Refrigerated case with low frost operation
Abstract
An open-front refrigerated case with reduced frost operation
includes a housing having an open front and defining a product
storage space therein. An air flow device is operatively coupled to
an air flow path to direct a flow of air over a dehumidification
coil for discharge as a dehumidified air curtain over the open
front. The dehumidification coil operates substantially frost-free
at a temperature of greater than 32.degree. F. A contact cooling
device and/or a gravity cooling device is disposed within the space
and arranged to receive a coolant from a coolant system, where the
dehumidified air curtain operates as a humidity tempering boundary
to minimize the humidity within the storage space, so that the case
operates in a substantially frost-free manner.
Inventors: |
Swofford; Timothy Dean;
(Midlothian, VA) ; Howington; Larry C.;
(Chesterfield, VA) |
Correspondence
Address: |
FOLEY & LARDNER LLP
777 EAST WISCONSIN AVENUE
MILWAUKEE
WI
53202-5306
US
|
Assignee: |
Delaware Capital Formation,
Inc.
|
Family ID: |
38860259 |
Appl. No.: |
11/455968 |
Filed: |
June 20, 2006 |
Current U.S.
Class: |
62/256 ;
62/272 |
Current CPC
Class: |
F25D 23/023 20130101;
F25D 17/042 20130101; F25D 21/04 20130101; A47F 3/0447 20130101;
F25D 25/028 20130101 |
Class at
Publication: |
62/256 ;
62/272 |
International
Class: |
A47F 3/04 20060101
A47F003/04; F25D 21/00 20060101 F25D021/00 |
Claims
1. An open-front refrigerated case with reduced frost operation,
comprising: a housing having an open front and defining a product
storage space therein; an air flow device operatively coupled to an
air flow path to direct a flow of air over a dehumidification coil
for discharge as a dehumidified air curtain over the open front,
the dehumidification coil operating substantially frost-free at a
temperature of greater than 32.degree. F.; at least one of a
contact cooling device and a gravity cooling device disposed within
the space and arranged to receive a coolant from a coolant system;
wherein the dehumidified air curtain operates as a humidity
tempering boundary to minimize the humidity within the storage
space.
2. The case of claim 1 wherein the coolant system comprises a
refrigeration system and the coolant is a refrigerant.
3. The case of claim 1 wherein the coolant system comprises a
secondary liquid coolant system.
4. The case of claim 3 wherein the secondary liquid coolant system
interfaces with a primary refrigeration system through a
chiller.
5. The case of claim 4 wherein the chiller is contained within the
housing.
6. The case of claim 1 wherein the chiller is a centrally located
chiller operable for use with a plurality of cases in a
facility.
7. A refrigerated display case comprising: a housing having an open
front and defining a space adapted to receive products; a
dehumidification device operating at a temperature greater than
32.degree. F.; an air flow device operable to direct a flow of air
over the dehumidification device and for discharge over the open
front as a dehumidified air curtain; at least one shelf arranged to
receive a flow of a coolant to provide contact cooling to the
products; a cooling system providing coolant to the shelf; wherein
the dehumidification device operates above freezing in a
substantially frost-free manner and the dehumidified air curtain
maintains a low humidity environment proximate the shelf so that
the shelf operates in a substantially frost-free manner.
8. The refrigerated display case of claim 7 wherein the air flow
device comprises a fan, and the fan and dehumidification coil are
located in a plenum formed by the housing.
9. The refrigerated display case of claim 7 wherein the coolant
comprises a refrigerant.
10. The refrigerated display case of claim 7 wherein the shelf
comprises a plurality of shelves oriented in a vertically stacked
arrangement.
11. The refrigerated display case of claim 10 wherein the coolant
comprises a liquid coolant provided by a secondary cooling system
that interfaces with a primary cooling system through a heat
exchanger.
12. The refrigerated display case of claim 11 wherein the secondary
coolant system comprises at least one flow regulation device
operable to maintain a first shelf at a first temperature and a
second shelf at a second temperature.
13. The refrigerated display case of claim 7 further comprising a
gravity cooling coil disposed in a top portion of the space.
14. The refrigerated display case of claim 7 further comprising a
gravity cooling coil disposed directly beneath the shelf.
15. The refrigerated display case of claim 7 wherein the
dehumidification device comprises a coil configured to receive a
supply of at least one of the coolant or a refrigerant.
16. The refrigerated display case of claim 7 wherein the
dehumidification device comprises a desiccant wheel.
17. A refrigerated display case comprising: a housing having an
open front and defining a space adapted to receive products; a
first coil operating at a temperature greater than 32.degree. F.;
an air flow device operable to direct a flow of air over the first
coil and for discharge over the open front as a dehumidified air
curtain; a second coil operating at a temperature below 32.degree.
F., the second coil disposed within the space to cool the products;
a cooling system providing coolant to the second coil; wherein the
first coil operates above freezing in a substantially frost-free
manner and the dehumidified air curtain maintains a low humidity
environment proximate the second coil so that the second coil
operates in a substantially frost-free manner.
18. The refrigerated display case of claim 17 wherein the first
coil comprises a dehumidification coil disposed external to the
space and adjacent to the air flow device.
19. The refrigerated display case of claim 17 wherein the second
coil comprises a gravity cooling coil disposed in a top portion of
the space.
20. The refrigerated display case of claim 17 further comprising a
shelf disposed within the space and the low humidity environment
and configured to receive the products.
21. The refrigerated display case of claim 20 wherein the shelf is
configured to receive a supply of the coolant to provide contact
cooling to the products and.
22. The refrigerated display case of claim 21 wherein the shelf
operates in a substantially frost-free manner in the low humidity
environment.
23. The refrigerated display case of claim 22 further comprising a
third coil disposed beneath the shelf and configured to receive a
supply of the coolant, the third shelf arranged as a gravity
cooling coil and operating in a substantially frost-free in the low
humidity environment.
24. A method of operating a refrigerated display case for low frost
performance, comprising: providing a housing defining a storage
space for products, the storage space having an open front, and an
air flow passage communicating with the open front; providing a
dehumidification coil communicating with the air flow passage;
providing an air flow device operable to direct a flow of air over
the dehumidification coil for discharge as a dehumidified air
curtain over the open front; providing a cooling device comprising
at least one of a contact-cooling shelf and a gravity cooling coil
within the space for cooling products; circulating a coolant to the
cooling device; and operating the dehumidification coil at a
temperature above 32.degree. F.
25. The method of claim 24, further comprising the step of
circulating a refrigerant through the dehumidification coil.
26. The method of claim 24 wherein the cooling device comprises a
contact cooling shelf and a gravity cooling coil, and the coolant
circulated to the contact cooling shelf comprises a liquid coolant
and the coolant circulated to the gravity cooling coil comprises a
refrigerant.
Description
BACKGROUND
[0001] The present invention relates to an open-front refrigerated
case. The present invention more specifically relates to an
open-front refrigerated display case having chilled shelves and/or
a gravity cooling coil. The present invention more specifically
relates to an open-front refrigerated display case having chilled
shelves and/or a gravity cooling coil, and an air curtain
dehumidified by a dehumidifying coil operating above 32.degree. F.
that prevents frost formation on the dehumidifying coil and
provides a low humidity boundary to minimize frost formation on the
chilled shelves and/or gravity cooling coil.
[0002] It is known to provide for a refrigerated case for storage
and presentation of food products (such as perishable meat, dairy,
seafood, produce, etc.). Such known refrigerated cases may include
those of a type typically having an open front to permit consumers
to reach in and select products from shelves within the case (e.g.
"self service" type cases, etc.). Open-front refrigerated cases
often have a main cooling coil operating at a temperature below
32.degree. F. to chill air that is distributed by a fan through
ducts. The chilled air is blown into the product storage space of
the case for cooling the products, and downwardly from a discharge
along a top front portion of the case to provide an "air curtain"
extending across the front of the case. The air curtain is intended
to form an "invisible thermal boundary" between the chilled product
storage space within the case and the warmer ambient air
surrounding a front of the case. The invisible thermal boundary of
the air curtain is intended to minimize "mixing" of surrounding
ambient-temperature air with the chilled air within the storage
space of the case and behind the air-curtain. However, the
operation of the main cooling coil at a temperature below
32.degree. F. tends to result in frost buildup on the cooling coil
over time as moisture in the air condenses and freezes on the
surfaces of the cooling coil, resulting in diminished performance
of the coil and increased energy consumption.
[0003] It is also known to provide refrigerated cases with chilled
shelves or pans to provide contact cooling for food products stored
and displayed on the shelves. Such cases are typically service-type
cases that are normally "closed" and provide access through doors
or the like to minimize the amount of moisture accumulation within
the storage space. However, such chilled pans also tend to
accumulate frost over time as moisture in the air space within the
case (and from the ambient air when doors to the case are opened)
and from the food products condenses and freezes on the chilled
shelves.
[0004] It is also known to provide refrigerated cases with
gravity-type cooling coils located in a top portion of the case.
Such cases are also typically service-type cases that are normally
"closed" and provide access through doors or the like to minimize
the amount of moisture accumulation within the storage space, and
to permit a natural circulation of air within the space as cooled
air from the gravity coil falls and warm air from the products
rises. However, such gravity type cooling coils also tend to
accumulate frost over time as moisture in the air space within the
case (and from the ambient air when doors to the case are opened)
and from the food products condenses and freezes on the surfaces of
the cooling coils.
[0005] Accordingly, it would be desirable to provide a refrigerated
display case of the open-front type that combines the advantages of
contact cooling of food products provided by chilled shelves and
the advantages of the humidity control provided by an air curtain,
in a way that minimizes or eliminates the accumulation of frost on
the chilled surfaces (e.g. shelves, air curtain dehumidifying coil,
etc.) of the refrigerated case. It would be desirable to provide a
refrigerated display case of the open-front type that combines the
advantages of cooling of food products provided by gravity-type
cooling coils and the advantages of the humidity control provided
by an air curtain, in a way that minimizes or eliminates the
accumulation of frost on the chilled surfaces (e.g. gravity cooling
coil, air curtain dehumidifying coil, etc.) of the refrigerated
case. It would also be desirable to provide a refrigerated display
case having a gravity coil and refrigerated shelves operating below
32.degree. F. for cooling the products in the storage area and an
air curtain dehumidified by an air curtain dehumidifying coil
operating at above 32.degree. F., so that the air curtain cooling
coil does not accumulate frost and the air curtain is sufficiently
cool and dry to temper or maintain a low humidity environment
within the storage space to minimize or eliminate frost
accumulation on the chilled shelves or the gravity coil.
[0006] Accordingly, it would be desirable to provide a refrigerated
display case having any one or more of these or other advantageous
features.
SUMMARY
[0007] The present invention relates to an open-front refrigerated
case with reduced frost operation. The case includes a product
storage space and at least one chilled shelf within the storage
space. A cooling system-provides a coolant for circulation through
the chilled shelf. An air curtain dehumidifying coil operating at a
temperature above 32.degree. F. is provided to dehumidify a flow of
air that is discharged downwardly in the form of an air curtain
across a front opening of the case to minimize a humidity level
within the storage space.
[0008] The present invention also relates to an open-front
refrigerated display case with reduced frost operation. The case
includes a product storage space and a gravity cooling coil
disposed in a top portion of the storage space. A cooling system
provides a coolant for circulation through the gravity cooling
coil. An air curtain dehumidifying coil operating at a temperature
above 32.degree. F. is provided dehumidify a flow of air that is
discharged downwardly in the form of an air curtain across a front
opening of the case to minimize a humidity level within the storage
space.
[0009] The present invention further relates to an open-front
refrigerated case with reduced frost operation. The case includes a
product storage space and at least one chilled shelf within the
storage space and a gravity cooling coil disposed within a top
portion of the storage space. A cooling system provides a coolant
for circulation through the chilled shelf and the gravity cooling
coil. An air curtain dehumidifying coil operating at a temperature
above 32.degree. F. is provided to dehumidify a flow of air that is
discharged downwardly in the form of an air curtain across a front
opening of the case to minimize a humidity level within the storage
space.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic representation of a side elevation
view of a refrigerated case having chilled shelves within a storage
space and an air curtain dehumidified by an air curtain
dehumidifying coil operating above 32.degree. F. according to one
exemplary embodiment.
[0011] FIG. 2 is a schematic representation of a side elevation
view of a refrigerated case having a gravity cooling coil disposed
within a top portion of a storage space and an air curtain
dehumidified by an air curtain dehumidifying coil operating above
32.degree. F. according to another exemplary embodiment.
[0012] FIG. 3 is a schematic representation of a side elevation
view of a refrigerated case having chilled shelves within a storage
space, and a gravity cooling coil disposed within a top portion of
the storage space, and an air curtain dehumidified by an air
curtain dehumidifying coil operating above 32.degree. F. according
to another exemplary embodiment.
[0013] FIG. 4 is a schematic representation of a side elevation
view of a refrigerated case having chilled shelves within a storage
space, and a gravity cooling coil disposed within a top portion of
the storage space, and an air curtain dehumidified by an air
curtain dehumidifying coil operating above 32.degree. F. according
to a further exemplary embodiment.
DETAILED DESCRIPTION
[0014] Referring to the FIGURES, a front-loading refrigerated case
10 of the open-front type having a storage space 16 for display of
chilled (e.g. refrigerated, frozen, etc.) products is shown
according to an exemplary embodiment. The case 10 is shown to
include an air curtain 14 (e.g. air stream, etc.) formed from a
flow of air that is dehumidified by an air curtain dehumidifying
coil 24. Unlike conventional air curtains that function to provide
primarily a thermal boundary to separate the low temperature
interior product storage space of the case from a warmer external
ambient environment surrounding the case (e.g. supermarket
atmosphere, etc.), the air curtain of the illustrated embodiments
is operated at an increased temperature and functions primarily as
a humidity tempering device to maintain a low humidity level within
the storage space. The dehumidified air curtain may also provide a
secondary benefit of serving, at least to some degree, as a thermal
boundary too. The low temperature of the food products within the
storage space is maintained primarily by contact cooling from
chilled shelves and/or the cooling effects from the circulation of
air from a gravity cooling coil disposed above the shelves. The
operation of the air curtain at an increased temperature (in
relation to conventional open-front refrigerated case air curtains)
is intended to prevent frost accumulation on the air curtain
dehumidifying coil, while also providing sufficient
dehumidification to the air curtain to maintain the product storage
space at low humidity to minimize or eliminate frost accumulation
on the chilled shelves and/or gravity cooling coil(s). The
combination of the dehumidification provided by the relatively
"warmer" air curtain and air curtain dehumidifying coil, with the
chilled shelves and/or gravity cooling coil to maintain the
temperature of the products in the storage space, is believed to
provide a relatively "frost-free" or reduced-frost refrigerated
case of the open-front type.
[0015] Referring to FIGS. 1-4, the operation of the
humidity-tempering air curtain 14 is shown according to an
exemplary embodiment. The case 10 is shown to include an air
curtain flow path 20 having an airflow device (shown as a fan 22)
and a dehumidification device 24 (shown as the air curtain
dehumidifying coil, but may also be a desiccant wheel or other
dehumidification device) for dehumidifying a flow of air that is
drawn in through a front portion of the case, and discharged from
an exit opening 26 shown along a top front portion of the case. The
air curtain dehumidifying coil 24 is shown located in a bottom
portion of the case adjacent to fan 22 and receives a source of
coolant from either a primary cooling system 40 (as shown for
example in FIG. 4) or a secondary cooling system 50 (shown for
example in FIG. 1). According to an alternative embodiment, the
dehumidifying device may be located at another suitable location,
such as within a rear portion of the case housing, including for
example, within air flow passage 20).
[0016] Unlike conventional open-front refrigerated cases that use a
common cooling coil to chill an air curtain (to provide a thermal
boundary across the open front) and to provide chilled air for
cooling the storage space and the products stored therein, the
dehumidified air curtain 14 operates primarily as a humidity
boundary and not as the primary source of cooling for the storage
space 16 and the products contained therein. Thus, the temperature
of the air curtain may be operated at a temperature that is higher
than the air curtains of conventional open-front cases. For the
embodiments where the dehumidification device is provided as a
coil, the dehumidifying coil 24 may receive a supply of coolant
from any suitable source.
[0017] As shown for example in the embodiment of FIG. 1, the coil
24 receives a supply of a liquid coolant from a secondary liquid
coolant system 50, where the temperature of the coolant may be
controlled by a chiller 42 that interfaces with the primary
refrigeration system 40. The chiller may be controlled for
operation of one case, or for a plurality of cases having similar
operating temperature requirements. According to the embodiment
shown in FIG. 1, the flow of liquid coolant through the coil 24 may
be controlled (e.g. "pulsed" on an open-closed manner or modulated
in a variable position manner) by a flow regulating device 28 (e.g.
valve, etc.) to adjust the rate of liquid coolant flow through the
coil 24. The operation and position of valve 28 may be controlled
by any suitable control system in response to suitable parameters,
such as a signal representative of the temperature of the coil 24,
a signal representative of the humidity of the air curtain 14, a
signal representative of the humidity within the storage space 16,
etc. Suitable instrumentation of a conventional type for providing
such signals (e.g. thermocouples, RTDs, humidity sensors, etc.) may
be provided at appropriate location and arranged to provide a
signal to a programmable control device such as a microprocessor to
provide the appropriate output signal to the valve 28. All such
operating and control schemes are intended to be within the scope
of the embodiments described herein.
[0018] As shown by way of example in FIG. 4, the coil may
alternatively receive a supply of refrigerant coolant from the
primary refrigeration system 40, which may also include an
electronic pressure regulator 45 or a superheat control valve 43 of
a conventional type to control the temperature of the refrigerant
coolant within the coil 24. The primary refrigeration system 40 and
the secondary liquid coolant system 50 may be configured in any
suitable arrangement to provide the desired dehumidification
performance for the air curtain and the desired temperature control
for the shelves and gravity cooling coils. As shown by way of
example in FIG. 4, the primary refrigeration system may be
configured to supply a refrigerant coolant to the gravity cooling
coils 32 and to the dehumidification coil 24, while the secondary
liquid coolant system may be configured to provide cooling to
shelves 30. All suitable combinations of the coils, shelves and
coolant supply systems are intended to be within the scope of the
embodiments.
[0019] According to the present embodiments, the temperature and
flow rate of the coolant through the air curtain dehumidifying coil
24 is regulated so that the dehumidifying coil 24 operates at a
temperature above freezing (i.e. 32.degree. F.) so that moisture
from the flow of air that condenses on the coil 24 remains in a
liquid state and is routed to a suitable receptacle (e.g. drip pan,
etc.) or drain (not shown), and does not freeze on the surface of
the dehumidifying coil 24. Operation of the dehumidifying coil 24
at a temperature above freezing is intended to prevent frost
accumulation on the surface of the air curtain dehumidifying coil
24. The dehumidification of the air curtain 14 is intended to
maintain a low humidity level within the storage space 16 by
tempering the surrounding ambient air and humidity with a
dehumidified layer of air. The air curtain dehumidifying coil 24
dehumidifies the flow of air used in the air curtain 14 to maintain
a low humidity level within the storage space 16. The low humidity
level within the space 16 permits the use of low temperature
cooling devices such as (for example) chilled shelves and/or
gravity coil(s) to cool the food products, in a manner intended to
minimize or eliminate the accumulation of frost on the surfaces of
the shelves or gravity coil(s).
[0020] According to another embodiment, the dehumidification device
may be non-coolant based and provided as a liquid desiccant,
desiccant wheel, or the like, where the dehumidification coil and
the supply of a coolant thereto are omitted. The dehumidification
device (such as a desiccant wheel) may be arranged within a bottom
or rear portion or top portion of the case housing for simple and
convenient replacement.
[0021] Referring to FIG. 1, case 10 is also shown to include
chilled (refrigerated, cooled, etc.) shelves 30 mounted within the
space 16 and arranged to receive chilled products for storage and
display. The chilled shelves 30 receive a supply of coolant for
chilling the shelves. The coolant may be circulated through
channels or passages formed within the shelves, or may be
circulated through tubing or coils contacting (or integrated with)
an underside of the shelf. As shown in the illustrated embodiment
of FIG. 1, the coolant may be a chilled liquid coolant, such as a
glycol-based fluid, provided by a secondary liquid cooling system
50 that circulates the coolant in a secondary cooling loop 52 to
the shelves 30 and to a heat exchange device shown as a chiller 42.
Chiller 42 is shown to interface with a "primary" cooling system
40, such as a refrigeration system (e.g. a direct expansion or
vapor-compression type refrigeration system, etc.) that operates to
chill the coolant circulating in the secondary cooling loop 52. The
primary cooling system and the secondary cooling system may be
provided in any one of multiple combinations for use with the case
(or multiple cases) in a facility. For example, the secondary
cooling system may be a local system provided at the particular
case location and interfaces with a centrally located primary
refrigeration system configured to interface with multiple cases.
Also, the secondary cooling system may be provided as a centralized
system that supplies coolant to multiple cases within a facility
(such as a supermarket, etc.) and is chilled by a single, remotely
located primary refrigeration system. According to an alternative
embodiment, the coolant may be provided directly by a single
refrigeration system and a "secondary" cooling system may be
omitted.
[0022] The coolant is provided at a temperature sufficient to
permit the chilled shelves 30 to provide a desired amount of
contact cooling to food products (or the like) disposed on the
shelves. According to one embodiment, the temperature range of the
coolant provided to the shelves 30 is below freezing, for example,
within a range of approximately 20.degree. F.-32.degree. F.
Alternatively, the temperature range of the coolant provided to the
shelves may be above freezing, for example, within a range of
approximately 32.degree. F.-38.degree. F. However, the coolant may
be provided at any suitable temperature that is appropriate to
maintain the desired temperature of the products disposed on the
shelves within the storage space. The relatively low humidity level
in the case is intended to allow the shelves to operate below
freezing without accumulating excessive amounts of frost on the
surfaces of the shelves.
[0023] Referring to FIG. 2, case 10 is also shown to include a
gravity cooling coil 32 disposed within a top portion of the
storage space 16 and arranged to receive a supply of coolant to
provide cooling to the products on conventional shelves 31 located
beneath the gravity coil 32. A single gravity coil 32 may be
provided at a top portion of the storage space (as shown) or
multiple gravity coils may be provided (e.g. one mounted beneath
each shelf, etc.). As shown in the illustrated embodiment of FIG.
2, the coolant may be a chilled liquid coolant, such as a
glycol-based fluid, provided by the secondary cooling system 50
that circulates the coolant in secondary cooling loop 52 to the
gravity coil(s) 32 and to the chiller 42. According to an
alternative embodiment, the coolant for the gravity coil(s) may be
provided directly by a refrigeration system and a secondary cooling
system may be omitted.
[0024] The coolant is provided at a temperature sufficient to
permit the gravity coil(s) 32 to provide a desired amount of
cooling to the food products (or the like) disposed on the shelves
31. According to one embodiment, the temperature range of the
coolant provided to the gravity coil(s) 32 is below freezing, for
example, within a range of approximately 20.degree. F.-32.degree.
F. Alternatively, the temperature range of the coolant provided to
the gravity coil(s) may be above freezing, for example, within a
range of approximately 32.degree. F.-38.degree. F. However, the
coolant may be provided at any suitable temperature that is
appropriate to maintain the desired temperature of the products
within the storage space. The relatively low humidity level in the
case is intended to allow the gravity coils 32 to operate below
freezing without accumulating excessive amounts of frost.
[0025] Referring to FIG. 3, case 10 is shown to include both
chilled shelves 30 and a gravity cooling coil 32 disposed within a
top portion of the storage space 16, where the shelves 30 and the
gravity coil(s) 32 are arranged to receive a supply of coolant to
provide cooling to the products on the shelves 30 located beneath
the gravity coil(s) 32. As shown in the illustrated embodiment of
FIG. 3, the coolant may be a chilled liquid coolant, such as a
glycol-based fluid, provided by the secondary cooling system 50
that circulates the coolant in a secondary cooling loop 52 to the
chilled shelves 30 and the gravity coil(s) 32 and to the chiller
42. According to an alternative embodiment, the coolant for the
chilled shelves and the gravity coil(s) may be provided directly by
a refrigeration system and a secondary cooling system may be
omitted.
[0026] Referring further to FIG. 1 by way of example, the coolant
is provided at a temperature sufficient to permit the combination
of the chilled shelves 30 and the gravity coil(s) 32 to provide a
desired amount of cooling to the food products (or the like)
disposed on the shelves. The shelves and the gravity coils may have
separate flow regulation or temperature control devices (shown
schematically as valves 54) intended to permit the shelves and the
gravity coil(s) to operate at different temperatures or coolant
flow rates, so that a product cooling profile within the storage
space of the case can be customized to suit products having
different temperature storage requirements. The coolant may be
provided at any suitable temperature and flow rate that is
appropriate to maintain the desired temperature of the products
within the storage space. The relatively low humidity level in the
case is intended to allow the chilled shelves and the gravity
coil(s) to operate below freezing without accumulating excessive
amounts of frost. The valves 54 may be operated in any suitable
manner, such as "open-closed" or "variable position modulation" to
maintain a desired temperature on each shelf and/or cooling coil.
The operation and control of valves 54 and thus temperature of the
shelves 30 and coils 32, may be provided by any suitable control
system, such as temperature sensors on the shelves and/or coils
providing signals representative of temperature to a programmable
control device operable to provide output signals to control
position of the valves 54 to maintain a desired temperature at each
shelf and/or gravity cooling coil.
[0027] According to any exemplary embodiment, an open-front type
refrigerated display case is provided that is intended to operate
in a relatively frost-free manner in comparison to conventional
open-front refrigerated cases. The case of the illustrated
embodiments uses a dehumidification device such as a coil operating
at a temperature above freezing (to prevent frosting of the coil)
to dehumidify a flow of air for use in an air curtain, where the
air curtain functions as a humidity tempering device to maintain a
relatively low humidity level within the storage space, while
chilled shelves and/or gravity cooling coil(s) are provided within
the storage space to maintain the desired temperature of food
products stored within the space. The dehumidified air curtain is
intended to permit operation of the chilled shelves and/or gravity
cooling coil(s) in a relatively frost-free manner, by providing a
humidity boundary that minimizes the level of moisture in the air
space proximate the shelves and/or gravity cooling coil(s).
Accordingly, the unique combination of an air curtain dehumidified
by a coil operating at a temperature above freezing, and contact or
gravity cooling elements within the storage space to cool the
products has resulted in an open-front type refrigerated display
case that is believed to operate in a manner that substantially
reduces the need for defrosting of the cooling surfaces of the
case.
[0028] According to any alternative embodiment, other types cooling
or dehumidifying devices or technology may be used to permit
operation of the case in a manner that reduces the humidity in the
vicinity of cooling surfaces that operate at a temperature below
freezing. Accordingly all such types of cooling and/or
dehumidification technology is intended to be within the scope of
the disclosure.
[0029] It is also important to note that the construction and
arrangement of the elements of the refrigerated case with reduced
frost operation as shown in the preferred and other exemplary
embodiments is illustrative only. Although only a few embodiments
of the present inventions have been described in detail in this
disclosure, those skilled in the art who review this disclosure
will readily appreciate that many modifications are possible (e.g.,
variations in sizes, dimensions, structures, shapes and proportions
of the various elements, values of parameters, mounting
arrangements, use of materials, colors, orientations, etc.) without
materially departing from the novel teachings and advantages of the
subject matter recited. For example, elements shown as integrally
formed may be constructed of multiple parts or elements, the plenum
and its inlets, outlets, and airflow devices may be arranged in any
suitable manner or otherwise varied to take advantage of the
dehumidified air curtain and the cooling elements within the
storage space. The length or width of the structures and/or members
or connectors or other elements of the case may be varied. It
should be noted that the elements and/or assemblies of the
refrigerated case may be constructed from any of a wide variety of
materials that provide sufficient strength or durability, in any of
a wide variety of colors, textures and combinations. Accordingly,
all such modifications are intended to be included within the scope
of the appended claims. Other substitutions, modifications, changes
and omissions may be made in the design, operating conditions and
arrangement of the preferred and other exemplary embodiments
without departing from the spirit of the appended claims.
[0030] The order or sequence of any process or method steps may be
varied or re-sequenced according to alternative embodiments. Any
means-plus-function clause is intended to cover the structures
described herein as performing the recited function and not only
structural equivalents but also equivalent structures. Other
substitutions, modifications, changes and omissions may be made in
the design, operating configuration and arrangement of the
preferred and other exemplary embodiments without departing from
the spirit of the appended claims.
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