U.S. patent application number 10/752134 was filed with the patent office on 2004-08-26 for refrigerated display merchandiser with improved air curtain.
Invention is credited to Alahyari, Abbas A., Saroka, Mary D..
Application Number | 20040163401 10/752134 |
Document ID | / |
Family ID | 32930203 |
Filed Date | 2004-08-26 |
United States Patent
Application |
20040163401 |
Kind Code |
A1 |
Alahyari, Abbas A. ; et
al. |
August 26, 2004 |
Refrigerated display merchandiser with improved air curtain
Abstract
A refrigerated merchandiser includes a display case defining a
product display region having an open-front isolated from the
ambient air of the store by means of a downwardly directed inner
air curtain of relatively cold refrigerated air and a downwardly
directed outer air curtain of relatively warmer air. The inner air
curtain discharges through a first air outlet at a first discharge
velocity and the outer air curtain discharges through a second air
outlet at a second discharge velocity, the second discharge
velocity being at least about 1.4 times greater than the first
discharge velocity, and most advantageously, from about 1.4 to
about 1.8 times greater than the first discharge velocity.
Inventors: |
Alahyari, Abbas A.;
(Manchester, CT) ; Saroka, Mary D.; (Manchester,
CT) |
Correspondence
Address: |
CARRIER CORPORATION
P.O. BOX 4800
CARRIER PARKWAY
SYRACUSE
NY
13221
US
|
Family ID: |
32930203 |
Appl. No.: |
10/752134 |
Filed: |
January 6, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10752134 |
Jan 6, 2004 |
|
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10374640 |
Feb 26, 2003 |
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Current U.S.
Class: |
62/256 |
Current CPC
Class: |
A47F 3/0447
20130101 |
Class at
Publication: |
062/256 |
International
Class: |
A47F 003/04 |
Claims
What is claimed is:
1. A refrigerated merchandiser including a display case defining a
product display region having an open-front viewing area, a first
air outlet associated with said display case for directing a first
air stream air generally downwardly across the front viewing area
along a first path, and a second air outlet associated with said
display case for directing a second air stream air generally
downwardly across the front viewing area along a second path
outwardly of the first air stream; said refrigerated merchandiser
characterized in that the first air stream exits the first air
outlet at a first discharge velocity and the second air stream
exits the second air outlet at a second discharge velocity, said
second discharge velocity being at least about 1.4 times greater
than said first discharge velocity.
2. A refrigerated merchandiser as recited in claim 1 further
characterized in that the ratio of said second discharge velocity
to said first discharge velocity is in the range from about 1.4 to
about 1.8.
3. A refrigerated merchandiser as recited in claim 1 wherein the
first air stream comprises relatively cooler air and the second air
stream comprises relatively warmer air.
4. A refrigerated merchandiser as recited in claim 1 wherein the
second air stream comprises ambient air.
Description
[0001] This application is also a continuation-in-part of copending
application Ser. No. 10/374,640, filed Feb. 26, 2003.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to refrigerated
display merchandisers of the type used in supermarkets, mini-marts,
convenience stores and other commercial establishments for
displaying and merchandising refrigerated or frozen products for
sale. More particularly, the present invention relates to
open-front refrigerated display merchandisers of the type wherein a
curtain of cold refrigerated air is passed downwardly across the
open front product display region of the merchandiser.
[0003] Refrigerated display merchandisers, also commonly referred
to as display cases, having open front display regions are commonly
used in supermarkets, mini-marts, convenience stores and other
commercial establishments for displaying and merchandising
refrigerated or frozen products for sale. The open front nature of
such display cases permits the consumer to simply reach into the
product display region to select and remove a product for purchase
without the inconvenience of needing to open a door to access the
product. Customarily, a curtain of cold refrigerated air is passed
downwardly at a relatively high velocity across the open front of
the display case to form an invisible boundary between the product
display region and the region of the store in front of the display
case. This air curtain not only helps retain cool refrigerated air
within the product display region of the display case, thereby
cooling the display product on the shelves of the display case, but
also functions to isolate, to a certain extent, the product display
region from the ambient air within the store. Ambient air that does
enter into open product display region undesirably causes increased
energy consumption by increasing the cooling demand on the
refrigeration system associated with the display case. Further,
such ambient air may also cause a local temperature rise within the
product display region sufficient to result in an undesirable rise
in product temperature that could adversely impact upon product
quality.
[0004] A problem encountered with when passing a curtain of
refrigerated air downwardly across the open front of the product
display region of the display case lies in the entrainment of
ambient air into the stream of refrigerated air forming the air
curtain. Turbulence exists at the boundary between the relatively
high velocity curtain air and the generally quiescent ambient air
lying in front of the display case. As a result of such turbulence,
some ambient air is undesirably entrained into the air curtain.
Multiple air curtain display cases have been developed in the prior
art to address this entrainment problem. For example, display cases
having two adjacent, parallel, but independently generated, air
curtains of refrigerated air are common in the art. Typically, such
as disclosed by Maehara in U.S. Pat. No. 4,633,677, the outermost
air curtain has a slightly higher temperature than the innermost
air curtain, so as to protect the colder innermost air curtain from
the impact of ambient air entrainment.
[0005] Also, it is well known in the art to establish a third air
curtain of relatively high temperature ambient air outwardly of one
or two refrigerated air curtains as a means of reducing entrainment
of ambient air from the store into the refrigerated air curtains.
Abraham, in U.S. Pat. No. 4,267,706, discloses establishing an
ambient air curtain outwardly of an innermost refrigerated air
curtain, with the outer ambient air curtain being directed
downwardly parallel to and adjacent to the inner refrigerated air
curtain. Beckwith et al, in U.S. Pat. Nos. 3,648,482 and 3,850,003,
MacMaster et al, in U.S. Pat. No. 3,827,254 and Roberts, in U.S.
Pat. Nos. 5,345,778 and 5,357,767, each disclose establishing an
ambient air curtain outwardly of a pair of refrigerated air
curtains. The curtain closest the product display region of the
display case is coolest, while the center curtain is at a
temperature slightly warmer than the innermost curtain, but
substantially cooler than the outermost ambient air curtain. The
center curtain of warmer refrigerated air serves to buffer the
innermost colder refrigerated air curtain from warm air intrusion
from the outermost ambient air curtain. The outermost curtain of
ambient air is directed substantially vertically downwardly, either
parallel to and adjacent the center air curtain or slightly
inwardly toward the center air curtain, so as to preclude
refrigerated air from the center and innermost refrigerated air
curtains from spilling out of the product display region of the
display case. The outermost ambient air curtain itself ideally
spills into the store near the base of the display case so as to
not be drawn into the air return inlets through which the
refrigerated air curtains return to the evaporator compartment.
[0006] Although generally effective to substantially reduce the
amount of entrainment of ambient air into the recycled refrigerated
air as compared to a single air curtain design, significant
entrainment still occurs in the case of refrigerated merchandisers
having two or three air curtains. It is generally recognized that
entrainment is reduced when adjacent air curtains in such multiple
air curtain designs have relatively the same velocity so that shear
instabilities at the interface between air curtains is minimized.
Therefore, in typical prior art merchandisers, the respective
discharge velocities of the separate air curtains, that is the
discharge velocities of the respective air streams as they pass out
of their respective nozzles at the top of the display case, are
designed to be substantially equal, be there two or three air
curtains present. However, as the air curtains flow downwardly, the
outer air curtain tends to spread and spill into the store thereby
reducing in velocity, while the inner air curtain tends to increase
in velocity due to buoyancy effects and the addition of air from
within the refrigerated display case. As a result, as the air
curtains pass downwardly, the shear instabilities at the interface
of adjacent air curtains increase, resulting in increased
entrainment of higher temperature, moister air into the inner air
curtain of refrigerated. Consequently, a need exists for an
improved air curtain system that addresses the problem of
entrainment into the inner air curtain of refrigerated air without
significant expense.
SUMMARY OF THE INVENTION
[0007] The refrigerated merchandiser of the present invention
includes a display case defining a product display region having an
open-front isolated from the ambient air of the store by means of a
downwardly directed inner air curtain of relatively cold
refrigerated air and a downwardly directed outer air curtain, most
advantageously of relatively warmer air. In accordance with the
present invention, the discharge velocity of the outer air curtain
is maintained at a velocity at least 1.4 times the discharge
velocity of the inner air curtain, and most advantageously in the
range of about 1.4 to about 2.4 times greater than the discharge
velocity of the inner air stream. In a preferred embodiment, the
outer air curtain comprises ambient air.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 illustrates a side elevation profile of a preferred
embodiment of a refrigerated merchandiser having an open-front
display case with a dual stream air curtain separating a first
environment within the display case from a second environment
external of the display case; and
[0009] FIG. 2 is a graphical presentation showing the variation of
load demand on the cooling system associated with the refrigeration
merchandiser as the air curtain velocity ratio changes.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0010] Referring now to FIG. 1, the refrigerated merchandiser 10
includes an outer cabinet 12 and an inner cabinet liner 20 that
defines within its bounds an open-front product display region 30.
The outer cabinet has a base 13, a rear wall 14 extending upwardly
from the back of the base 13, a top wall 15 extending forwardly
from the rear wall and a pair of side walls 16 extending vertically
from the base 13 to the top wall 15 and forwardly from the rear
wall 14. The inner cabinet liner 20 has a top panel 28, a back
panel 26, a bottom panel 24 and opposed side panels 23 which
together bound the open-front product display region 30. Each of
the cabinet base 13, rear wall 14, top wall 15 and side walls 16 is
insulated, as in conventional practice, to thermally isolate the
interior of the cabinet 12, including the product display region
30, from excessive heat transfer therethrough.
[0011] Perishable product 80 being merchandized may be displayed on
shelves 18 disposed within the product display region 30 and upon
the upper surface of the bottom panel 24. The product display
region 30 has an open front 25 so as to permit consumers to not
only view, but also reach into the product display region 30 to
select and remove items of product 80 that they desire to purchase.
Product display region 30 is cooled in a conventional manner to a
desired product temperature, typically to a temperature between
-10.degree. F. to less than about 40.degree. F., depending upon
what product is being merchandised therein and whether the product
is frozen or non-frozen.
[0012] The refrigerated merchandiser 10 further includes a
refrigeration compartment 40, typically disposed in the portion of
the display cabinet 12 between the base 13 and the bottom panel 24,
as depicted in FIG. 1, wherein components of the refrigerant
system, typically a tube coil evaporator 50 and a air mover 60,
such as for example one or more fans, are housed. However, it is to
be understood that the specific type of air mover employed is not
relevant to or limiting of the present invention. As in
conventional practice, refrigerant passing through the tubes of the
evaporator 40 cools air passing over the surface of the evaporator
tubes. The refrigerant is typically supplied from a remote
refrigeration unit located elsewhere within the store. However, it
is to be understood that the present invention may also be employed
on stand-alone refrigerated merchandisers that include their own
refrigeration unit for providing the cold refrigerant.
[0013] An air circulation duct 32 is formed between the rear wall
14 and the top wall 15 of the outer cabinet 12 and the back panel
26 and top panel 28, respectively, of the inner cabinet liner 20.
Air mover 60 serves to direct air from air inlet 42 through the
compartment 40 so as to traverse evaporator 50, and thence through
duct 32 to a first air outlet 34. As noted before, this circulating
air has been cooled to a desired temperature as it traverses the
evaporator 50. From the first air outlet 34, the cool refrigeration
air is directed via vanes provided within the first air outlet 34
downwardly along first path across the open front 25 of the product
display region back to air inlet 42. Thus, the refrigerating air is
recycled and repeatedly recirculated through the compartment 40 and
duct 32 to converse energy expended in cooling the refrigeration
air. Further, through the afore-described cooling arrangement, a
cool air curtain 45 is formed across the open-front product display
region 30 from top to bottom thereof. To provide further cooling
air directly to the product display region 30, a plurality of
openings 24 may be provided in the back panel 26 through which a
portion of cold refrigerating air circulating through duct 32 may
pass directly into the product display region 30. This
refrigerating air will also be drawn by the air mover back through
the air inlet 42 into the compartment 40 to be recirculated.
[0014] A second air outlet 70 is provided outwardly of the first
air outlet 34 at the top front of the cabinet 12. In contrast to
existing refrigerated merchandisers, second air outlet 70 serves to
direct relatively warm air generally downwardly along a second path
lying outwardly of the first path followed by the cool
refrigerating air. In this manner, a relatively warm outer air
curtain 65 is formed outside, i.e. further away from the product
display region 30, of the relatively cool inner air curtain 45. The
relatively warm outer air curtain 65 serves as a buffer between the
relatively cool inner air curtain 45 and the ambient environment of
the store. Further, when the outer air curtain 65 reaches the base
region of the display cabinet 12, it spills outwardly into the
store rather than into the air inlet 42 in the forward end of the
base portion of the cabinet. Consequently, the entrainment of warm
air into the relatively cool inner air curtain and subsequent
passage through inlet 42 into the compartment 40 is minimized,
thereby reducing energy consumption in cooling the recirculating
refrigeration air.
[0015] The first air outlet 34 and second air outlet 70 are located
at top and forward region of display case 12, with the second air
outlet 70 being located outwardly of the first air outlet 34, that
is, closer to the front of the display cabinet 12. As noted
previously, first air outlet 34 is in communication with duct 32
and directs relatively cool air driven by air mover 60 downwardly
across open front of the product display region 30 to form the
inner air curtain 45. The second air outlet 70 is in fluid
communication with a source of relatively warm air, for example
ambient air from the store, and directs relatively warm air driven
by a second air mover 72 associated therewith downwardly to form an
outer air curtain 65.
[0016] The outer air curtain 65 is directed downwardly at a
discharge velocity that is at least 1.4 times greater than the
discharge velocity of the inner air curtain 45. The term discharge
velocity refers to the velocity of the air stream discharging from
its respective air outlet at the top of the display case 30. Ergo,
the discharge velocity of the inner air curtain 45 is the velocity
of the air stream discharging from air outlet 34 and the discharge
velocity of the outer air curtain 65 is the velocity of the air
stream discharging from air outlet 70. Most advantageously, the
discharge velocity of the outer air curtain 65 is maintained at a
level of about 1.4 to about 2.4 times faster than the discharge
velocity of the inner air stream 45.
[0017] Referring now to FIG. 2, the vertical axis thereof
represents the load reduction factor, which is the refrigeration
load of the dual air curtain compared to the load for an inner air
curtain only, and the horizontal axis represents the ratio of the
velocity of the outer air curtain in that of the inner air curtain.
Accordingly, the lower the load reduction factor, the more
effective is the dual air curtain. As illustrated in FIG. 2, the
effectiveness of dual parallel air curtains as a barrier in
reducing passage of flow across the air curtain is maximized by
maintaining the ratio of the discharge velocity of the outer
curtain to the discharge velocity of the inner curtain within the
range of from about 1.4 to about 1.8. Maintaining the air curtain
velocity ratio within this range minimizes the velocity gradient,
and therefore shear instabilities, between the adjacent air
curtains along the length of the interface between the adjacent air
curtains, thereby resulting in less entrainment of air from the
higher velocity air curtain into the lower velocity air curtain.
Therefore, an very effective separation barrier may be maintained
between two environments through use of the present invention
through a dual air curtain of parallel streams of a first and a
second fluid by maintaining the discharge velocity of the outer air
stream a level of about 1.4 to about 1.8 times faster than the
discharge velocity of the inner air stream.
[0018] The aforementioned description is exemplary rather than
limiting. Many modifications and variations of the present
invention may be recognized by those skilled in the art in light of
the above teachings that will fall within the spirit and scope of
the present invention. The preferred embodiments of this invention
have been disclosed. Accordingly, within the scope of the appended
claims, the invention may be practiced otherwise than as
specifically described. For this reason the following claims should
be studied to determine the true scope and content of this
invention.
* * * * *