A refrigerated showcase has a front opening through which a consumer
can view and access foodstuffs on display. The foodstuffs are cooled
by coolant air introduced through a slanted, perforated, interior
panel located near a rear wall of the showcase. An air curtain directed
downwardly at the front opening minimizes coolant air loss through
the opening. Lips are applied and extended from edges of vertical
sides of the access opening to reduce the loss of coolant air through
the air curtain. Thus, relative flows of the coolant air and the
air curtain are maintained inside the showcase.
What is claimed is:
1. For a refrigerated showcase wherein the showcase has an opening
in front thereof through which a consumer can view and access foodstuffs
on display therein, wherein foodstuffs in the showcase are cooled
by coolant air introduced from a perforated panel inside the showcase,
and wherein the showcase includes an air curtain generated within
and directed downwardly at the opening, a method of developing parameters
for balancing relative air flows of the coolant air and the air
curtain to minimize loss of coolant air through the opening, said
method comprising the steps of:
(a) adjusting the relative flows of the air curtain and the coolant
air to obtain a stable air curtain;
(b) introducing a visible additive to the coolant air so as to
enable observation of and identification of any coolant air escaping
at a periphery of the opening in the front; and
(c) applying lips to extend from edges of vertical sides of the
front into the opening so as to control the loss of coolant air
through the air curtain.
2. In a self-service refrigerated showcase having therein an enclosure
for display of foodstuffs, said enclosure having a front access
opening defined at its vertically elongated sides by housing side
walls, said enclosure further having a perforated interior panel
through which coolant air is introduced and passed over the foodstuffs,
said enclosure also having a channel means for forming an air curtain
directed downwardly across the front access opening, an improvement
means for minimizing coolant air loss through the front access
opening, said minimizing means including a lip on each of the housing
side walls extending along at least a portion of the vertically
elongated sides, said lip being of a size such that coolant air
loss at the sides of the front access opening is reduced.
3. The improvement of claim 2 wherein the lip extends along the
entire length of each of the housing side walls.
BACKGROUND OF THE INVENTION
1. Field of the Invention.
The present invention relates broadly to refrigerated showcases,
particularly open-fronted display and storage cases with air curtains.
More specifically, the present invention relates to a refrigerated
showcase having an opening through which a consumer can view and
access stored items on display and to such a showcase wherein cooling
air is introduced through a perforated interior panel with the coolant
air maintained within the refrigerated compartment by an air curtain
passed downwardly within the showcase opening.
2. Description of the Related Art.
An example of this type of showcase is described in U.S. Pat. No.
3,696,630 granted on Oct. 10, 1972, to Bressickello who discloses
various self-service showcases constructed with front access openings
for the purpose of displaying comestibles such as meat, eggs and
vegetables. In such showcases, the cooling system includes a refrigerant
coil, also known as an evaporator coil, which is located in such
a position so as to cool air circulating through the showcase.
The refrigerant coil is sometimes oriented above a relatively small
drip pan, also referred to as a dissipater pan situated in a location
so as to collect condensation from the coil. When the water level
rises to a predetermined level, this condition is sensed and a pump
is activated to lift the water to an overhead dissipater pan arranged
on top of the showcase. The dissipater pan may include a heating
coil to dissipate any accumulated water. Other showcases eliminate
condensation from the refrigerant coils by a drainage system that
communicates with a floor sink.
An example of a showcase of the type where condensation from the
evaporator coil is pumped to a dissipater pan arranged on top of
a cabinet of the refrigerated showcase is illustrated in U.S. Pat.
No. 4,766,737 granted on Aug. 30, 1988, to Baxter, II. In this prior
art device, a high temperature coil of the condenser assembly is
associated with the lowermost of an array of dissipater pans in
order to effect the transfer of heat to the condensate which has
been pumped up to the dissipater array atop the cabinet of the refrigerated
The open-fronted, refrigerated showcases with air curtains in the
prior art have reached a level of efficiency such that additional
improvements are not readily achieved.
It is well known in the prior art to use perforated wall dividers
and/or rear panels which are angled to form an air plenum in association
with the back of the showcase. These air plenums are shaped to have
a decreasing volume through which cooled air is passed upwardly
with the flow also passing through perforations in the wall dividers
into the refrigerated showcase. This feature is illustrated in U.S.
Pat. No. 3,696,630 previously mentioned and in U.S. Pat. No. 5,345,778
issued on Sep. 13, 1994, to Roberts.
It is also known to route cooled air to a bottom portion of cooling
compartments where foodstuffs are stored. Bottom storage bins, where
foodstuffs are placed to replenish the display shelves located above
the storage area, are commonplace. However, cooling the storage
area is difficult to do. Prior art devices have cooled the storage
area by diverting a portion of the cooled air which is flowing upwardly
from housings in which evaporator coils and air-moving fans are
arranged. An example of such an arrangement is found in U.S. Pat.
No. 5,345,778 just mentioned.
SUMMARY OF THE INVENTION
In accordance with the present invention, three methods of improving
air curtains in open-fronted refrigerated showcases have been incorporated
in the refrigerated compartment, in the refrigerant system atop
the cabinet, and in the air circulation system.
As shall be fully explained below, one purpose of the present invention
is to achieve optimal heat exchange by continuously trapping particles
suspended in the air that flows into the components of the refrigerant
system which over time becomes fouled and impedes air flow and/or
the efficiency of the heat exchange. In particular, an air filter
is used atop the showcase. This air filter and precondenser coils,
situated beneath the air filter, are both exposed and susceptible
to fouling. Advantageously, these elements of the present refrigeration
system are cleaned by condensate originating at the evaporator coils.
This condensate is pumped from a lower drip pan up to the top of
the showcase, then expelled over the air filter. The condensate
then travels from the air filter over the precondenser coil into
the dissipater pan. The precondenser coil, preferably made of copper
tubing, is inserted between the compressor and the condenser coil.
As the refrigeration gas is sucked from the evaporator coil, the
compressor places the gas under a higher pressure, thus raising
the gas temperature. The hot gas is then pushed into the precondenser
coil which has a sufficient length to evaporate the water that lands
in the dissipater pan. The lengthy copper tubing coil between the
compressor and the condenser coil functions to evaporate the water
which has collected during the operation of the refrigerated show-case.
The precondenser coil is situated in the dissipater pan, suitably
resting on the bottom of the pan, with at least a portion of the
coil exposed to the atmosphere in the open section of the top of
the showcase. The precondenser coil also sits forward of the face
of the air filter. Preferably, a major portion of the precondenser
coil is exposed to the atmosphere. The precondenser coil also assists
the condenser coil by precondensing the refrigerant. The air is
pulled through the space where the filter, precondenser and dissipater
pan is located. The air then circulates outside the precondenser
coil and acts as a heat exchange medium. Precondensing refrigerant
gas into liquid, moreover, makes the condensing system more efficient.
Another aspect of the present invention, as shall also be further
explained below, is to minimize coolant air loss through the showcase
opening. This advantage is achieved by a method of identifying,
measuring and ameliorating coolant air loss by providing a lip along
vertical sides of the opening in the refrigerated compartment. The
lips extend vertically along at least a portion of each of the two
vertical sides of the opening where, as it has been discovered,
the loss of cooled air from the refrigerated compartment is greatest.
The present invention also provides an apparatus for assuring proper
cooling at the bottom of the refrigerated compartment of the showcase.
A further aspect of the present invention relates to the use of
an air divider and plenum arrangement which directs the coolant
air through perforations in the back of the refrigerated compartment
so that the coolant air flows over foodstuffs which are stored at
the bottom of the refrigerated compartment in an area beneath the
lowermost display shelf. In other words, a diverter and plenum arrangement
is utilized to achieve routing of the coolant air to the bottom
of the refrigerated compartment below the lowermost display shelf
in a facile manner.
It has also been found that, in refrigerated showcases wherein
there is an opening in the front thereof through which a consumer
can view and access foodstuffs on display, these foodstuffs in the
showcase are cooled by cold air introduced from a perforated panel.
Such refrigerated showcases include an air curtain generated within
and directed downwardly from the top of the opening. After a determination
of the flow rate, the loss of coolant air through the air curtain
can be either reduced or prevented altogether by using lips that
extend from the vertical edges partially into the opening.
The following method can be used to determine the dimensions of
the lips that limit coolant air loss through the air curtain. In
open-faced, refrigerated showcases, a 4" lip on each side has
been found suitable to minimize the coolant air loss along the vertical
edges of any refrigerated compartment which has an opening of about
56" in height. The method of determining the size of the lips
needed for the vertical edges involves several steps.
First, load the refrigerator shelves with the product to be refrigerated
and displayed, preferably at a desirable product temperature sufficient
to avoid the possibility of spoilage. Actually, this step can be
omitted, but it is preferred to use a stocked compartment.
Second, adjust the rate of flow of the coolant air to obtain a
stable air curtain. This step is achieved by producing a nominal
air flow of 500 cubic feet per minute by four fans which are each
rated at 125 cubic feet per minute so that an actual air flow rate
of about 330 cubic feet per minute is obtained.
Third, introduce a visible additive, such as artificial smoke,
to the circulating air in order to enable observation and identification
of any air escaping at the periphery of the front opening.
Fourth, apply a first lip extending from one vertical side edge
into the opening and a second lip extending from another opposite
vertical side edge into the same opening.
Fifth, observe, by increasing and/or decreasing, the extension
of the lips into both side edges of the opening. When the escape
of air through the air curtain is minimized at the vertical periphery
of the opening in the refrigerated showcase, the optimal lip size
has been empirically determined.
The lips are then affixed to the vertical side edges which extend
into the opening in the showcase a distance based on the observations
made in order to limit the loss of coolant air through the air curtain.
Thus, in accordance with the present invention, the loss of coolant
air which is passed over the displayed products is minimized. The
coolant air then emerges from the refrigerated compartment for recycling
with the circulating air forming the air curtain at the opening
in the showcase. As heretofore noted, the optimum conditions for
operation and determination of lip size are identified empirically
by observing and adjusting the size of the lips which minimize the
loss of coolant air at the vertical peripheries of the opening in
the refrigerated compartment.
Furthermore, the controlled flow of coolant air through perforated
openings in the panel is facilitated by an air divider and plenum
arrangement that provides for adequate distribution of the coolant
air to the food storage area which is located at the bottom of the
refrigerated compartment, typically beneath the first storage shelf.
As air is ejected upwardly by the four fans in the fan housing,
the air is pushed between the back wall which is plumbed straight
and the perforated panel which is inclined slightly backwards by
approximately six degrees from its vertical axis. The perforated
panel has at its lower end the air divider and plenum arrangement
situated beneath the first display shelf. The air divider and the
plenum arrangement are installed to force air flow through the perforated
panel into the bottom storage section of the refrigerated compartment.
Thus, air flow equilibrium throughout the perforated panel, including
the bottom storage section of the refrigerated compartment, is accomplished.
This equilibrium is achieved by forcing air to be approximately
the same amount in all spaces where the products are placed. The
reason for this result is believed to be that the air travels fastest
when it is nearest to the fans, so that the air travels to the upper
part of the panel and crosses through the perforations with great
The multiple fans, which move cooled air over the evaporator coils
situated in the bottom of the refrigerated compartment, reduce condensation
on the evaporator coils that are used to cool the air circulating
in the showcase so that icing is reduced on the evaporator coils.
Water collecting on the evaporator coils is captured in an evaporation
tray situated below the evaporator coils and is pumped to the top
of the showcase where the condenser is located. At the top, the
water sequentially is passed over a filter which functions as a
water evaporator and also functions to remove particulate matter
and other foulants, whereby the water from the evaporator coils
functions both to clean the filter and to cool the air passing through
the filter before the air contacts the condenser coils of the refrigeration
system. The water runs from the filter to the dissipater pan and
then to the precondenser coils carrying refrigerant from the compressor.
These precondenser coils are thus cooled by cold water originating
at the evaporator coils. The filtered air passing over the condenser
coils, which air is further cooled before contact by the water,
passes over and/or through the filter before absorbing heat produced
during refrigerant condensation. At the same time, the rate of evaporation
from the dissipater pan lying under the precondenser coils is substantially
increased and the risk of water overflow is minimized. The heat
generated during compression is exchanged through both the condenser
coils and the precondenser coils which comprise another set of coils
located downstream of the condenser coils. The precondenser coils
in essence function as heating coils to assist in the evaporation
of water from the dissipater pan using the heat of condensation,
thereby providing two desirable functions using the energy available
within the refrigeration system itself, namely removing heat from
the compressed refrigerant and adding heat to the condensate which
accumulates in the dissipater pan.
Furthermore, the present invention relates to a self-service refrigerated
showcase having therein an enclosure for the display of cooled foodstuffs.
The enclosure has a front access opening defined by top, side and
bottom housing panels. At its sides, the enclosure is defined by
vertically elongated strips corresponding to the side housing panels.
This enclosure provides access to the foodstuffs on display.
Also, the enclosure has other advantageous features. For example,
there is a perforated panel through which coolant air is introduced
and passed over the foodstuffs. Also, there is a top panel having
near to the forward part thereof a structure for forming an air
curtain which moves coolant air downwardly within the front access
opening after diverting the coolant air from the perforated panel.
This coolant air originated from a space behind the perforated panel
before reaching the access opening.
In accordance with the present invention, a structure is provided
for minimizing air loss through the front access opening. This structure
is a lip extending from each of the housing side walls along at
least a portion of the length of the opening. In this way, coolant
air loss which has been observed to occur predominantly at the vertical
periphery of the opening is substantially prevented.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top, partially cutaway, perspective view of the refrigerated
showcase of the present invention.
FIG. 2 is a schematic view of the cooling system of the refrigerated
FIG. 3 is a top perspective view of the lip structure of the refrigerated
FIG. 4 is a schematic side elevational view of the air flow system
within the refrigerated showcase.
FIG. 5 is an exploded perspective view showing air flow through
a perforated panel within the refrigerated showcase.
FIG. 6 is a detailed side elevational view showing the air flow
through the perforated panel illustrated in FIG. 5.
FIG. 7 is a detailed top plan view of fan motors for circulating
air flow through the perforated panel illustrated in FIGS. 5 and
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 1 is a view of an overall refrigerated showcase with several
cutaway parts. A compressor 7 and its associated components are
situated beneath a grid cover 2 on top of the showcase. The principal
associated components are a liquid line filter dryer 1, a sight
glass 3, a fuse switch 4, a main switch 5, and a main "J"
box 6 for supplying electric power. A suitable condenser fan motor
8 is provided by the LRC Coil Co., 9435 Sorensen Avenue, Santa Fe
Springs, Calif. 90670. The condenser fan motor 8 is sold as a component
of LRC Unit No. F3AM-A077. Performance data is as follows:
PERFORMANCE DATA R-22 CAPACITIES (BTUH) AT 90.degree. F. AMBIENT
SATURATED TEMPERATURE/ PRESSURE AT MAXIMUM COMPRESSOR SUCTION UNIT
AMBIENT 30.degree. F. 25.degree. F. 20.degree. F. 15.degree. F.
10.degree. F. MODEL NO. HP COMP AT 25.degree. F. 54.8# 48.6# 42.9#
37.6# 32.7# __________________________________________________________________________
F3AM-A051 1/2 JRF4 106.degree. 4,740 4,290 3,860 3,460 F3AM-A059
1/2 JRF4 119.degree. 5,890 5,330 4,760 4,280 3,800 F3AM-A074 3/4
RSN6 112.degree. 8,310 7,710 7,020 6,300 5,560 F3AM-A077 3/4 RRG4
114.degree. 8,070 7,350 6,570 5,810 5,105 F3AM-A078 3/4 RSN6 113.degree.
7,403 6,730 6,030 5,340 F3AM-A101 1 REB3 112.degree. 10700 9,740
8,730 7,730 6,750 F3AM-A102 1 REY3 105.degree. 12100 11100 10000
8,980 7,990 F3AM-A105 1 REK3 120.degree. 10700 9,600 8,540 7,570
6,610 F3AM-A175 13/4 CRC1 116.degree. 15500 13800 12200 10700 9,110
F3AM-A201 2 CRD1 113.degree. 16300 14800 13100 11500 9,140 MAXIMUM
65.degree. F. 65.degree. F. 65.degree. F. 65.degree. F. 40.degree.
F. RETURN GAS TEMP. __________________________________________________________________________
Notes: The return gas temperature is restricted when operating at
10.degree. F. suction temperature. See the far right column above.
Operating at higher return gas temperatures will shorten compressor
life. Refer to AE Bulleti 41292 for additional information. Refer
to the table above for the maximu allowable operating ambient temperature
for the unit. This is the maximum permitted temperature of the air
entering the condenser coil so as not to exceed the maximum permitted
# compressor condensing temperature of 140.degree. F. (130.degree.
F. at 10.degree. F. suction). Values are determined at suction with
a clean, unobstructed condenser coil. At 30.degree. F., when applicable,
reduce the allowable ambient temperature by 5.degree. F. For additional
units, refer to Form 3.0905 (R22 High Temperature Units). Capacities
are rated at the maximum return gas temperatures shown above and
5.degree. F. subcooling. Pressures are liste in PSIG (#) and # reflect
the suction pressure at the compressor intake jet. Temperatures
shown are the corresponding saturation temperatures. Saturation
conditions at the evaporator will be higher due to any pressur drop
in the suction line.
A water evaporator filter 11 is placed over the face of a condenser
coil box 9. This filter 11 prevents airborne particulate matter
from fouling the condenser coil box 9. Air drawn by the condenser
fan motor 8 first passes through the filter 11 and then through
the condenser coil box 9. The filtered air is then free of contaminants
which can foul the condenser coils within the box 9. If excess water
accumulates in an underlying dissipater pan 13 which holds a copper
precondenser coil 12, the water is drained down via an overflow
line 14 into a drip pan 20. Water originating from the drip pan
20 is pumped upwardly by a water pump 19 powered by an electric
J-box 18 via a water pump line 15 which leads into a water intake
tube 10. From the tube 10, the water flows downwardly over the filter
11 and then passes downwardly over the precondenser coil 12 which
is located in the dissipater pan 13. Optionally, a spray device
can be provided below the filter 11 to distribute the water onto
the precondenser coil 12 more evenly or in any other preselected
manner. A major portion of the precondenser coil 12 is exposed to
the atmosphere and rests on the bottom of the dissipater pan 13.
The water evaporates into the atmosphere from the dissipater pan
In order to achieve a more uniform distribution of the condensate
water over the entire face of the filter 11, a perforated distribution
pan (not shown) may be placed above the filter 11. Likewise, in
order to achieve a more uniform distribution over the entire precondenser
coil 12, a perforated pan (not shown) may be placed beneath the
filter 11 but above the coil 12.
As best shown in FIG. 2, the overflow line 14 leads out of the
dissipater pan 13. The precondenser coil 12 in the dissipater pan
13 is placed in the coolant line between the condenser 7 and the
condenser coil box 9. The coolant is then passed from the precondenser
coil 12 to the condenser coil box 9 through which cool air is blown
by the adjacent condenser fan motor 8. The coolant then goes sequentially
through a receiver 28, the liquid line filter dryer 1, and the sight
glass 3. After leaving the sight glass 3, the coolant flows down
to an expansion valve 24.
Returning to FIG. 1, the coolant exits the expansion valve 24 and
then goes to evaporator coils (not shown) located in a coil housing
17 where the air circulated in the refrigerated showcase is cooled.
The precondenser coil 12 is made of 1/4" copper tubing which
is 30' long and which is coiled to fit inside the dissipater pan
13. A major segment of the coil 12 is preferably placed forward
of the filter 11. The top of the condenser coil box 9 and the condenser
fan motor 8 form a contiguous top surface which covers these units.
As shown in FIG. 2, this arrangement ensures that the air drawn
through condenser coils 39 inside the box 9 is first drawn through
the filter 11 where the air is cooled and cleaned.
As seen in FIG. 1, forward of the filter 11, the top of the refrigerated
showcase is exposed to the atmosphere by the open-mesh grid cover
2 to facilitate the evaporation of the water warmed by the heat
absorbed from the precondenser coil 12 in the pan 13.
Because the grid cover 2 has an open mesh, the section rearward
of the condenser fan motor 8 is also exposed to the atmosphere.
The compressor 7 and the components associated with the compressor
7 and any other equipment that is used to effect the return of the
compressed liquid coolant to the bottom portion of the showcase
are not highly vulnerable to fouling by airborne contaminants. Thus,
they may be situated in the rearward open section on top of the
Air from the condenser fan motor 8 is passed through the condenser
coil box 9 into the open section behind the condenser fan motor
8. This air which has been cleaned by the filter 11 serves to circulate
air around the components in the top section and to carry out particles
through the open-mesh grid cover 2, thus helping to keep the rearward
part of the top section clean.
FIG. 3 illustrates a front opening of the refrigerated showcase
through which a customer can see and access food-stuffs. A fluorescent
lamp 26 sheds light on products in the showcase. Mirrors 23 may
be placed inside the showcase to reflect light as an aid to customer
viewing. A signage track 25 holds a sign (not shown) to attract
customer attention. To ensure stability, the showcase has lower
steel corners 21.
Lips 51 and 52 are affixed to two vertical side edges 53 and 54.
The lips 51 and 52 extend the edges 53 and 54 formed by side walls
55 and 56. The lips 51 and 52 and portions of the side walls 55
and 56 may be made of a clear plastic material which has the advantage
of allowing each customer a side view of the products.
The preferred outside dimensions of the refrigerated showcase are
50.75 inches wide, 81 inches high, and 30 inches deep. The preferred
inside dimensions are 48 inches wide, 59 inches high, and an average
of 20 inches deep. A two-part interior perforated panel 27 is slanted
and will be discussed later in regard to FIG. 4. Clear portions
of the side walls 55 and 56 are about 16 inches wide and 56 inches
For showcases with the internal dimensions illustrated in FIGS.
1, 3 and 4, an air flow rate of 330 cubic feet per minute is preferred
and the width of the lips 51 and 52 is about four inches for a 56-inch
height of the opening.
To describe the provision for adequate air flow to the bottom of
the refrigerated compartment, see FIGS. 4-7. This aspect of the
invention relates to an auxiliary air handling mechanism.
Referring first to FIG. 5, there is a lower perforated panel 27A.
An air divider 102, also called a diffuser top, divides air from
an air source into a first portion and a second portion. A first
plenum 100, also called a diffuser pan, is disposed behind the panel
27A intermediate side edges 27E and sits below the air divider 102.
The air divider 102 has on open bottom configuration for receiving
the first portion of air from the air source and is preferably attached
by fasteners (not shown) to the panel 27A.
Referring now to FIG. 4, the air divider 102 is attached to the
back of the lower perforated panel 27A which, with an upper perforated
panel 27B, forms the entire two-part interior slanted panel 27 of
the refrigerated compartment. The first plenum 100 preferably has
an open top configuration for receiving the first portion of air
from the air divider 102. A second plenum 106 extends vertically
between the back of the panel 27 and a rear wall 101.
As seen in FIG. 6, the air divider 102 extends further from the
lower panel 27A towards the rear wall 101 than the plenum 100. An
upper edge 100E of the first plenum 100 is attached to the coil
housing 17 for the air source. Alternatively, the air divider 102
may be attached to the coil housing 17. However, this arrangement
is not shown.
Nevertheless, in both arrangements, the second portion of the air
from the air source inside the coil housing 17 is directed upwardly
through the second plenum 106. Also, as seen in FIG. 6, a lower
shelf 29 is held in place by a shelf support 22 mounted on the upper
As best shown in FIG. 7, the air source in the refrigerated showcase
is four evaporator fan motors 16 inside the coil housing 17. The
J-box 18 provides electric power for the fan motors 16 and the water
pump 19. The rear wall 101 has interior insulation 107 to reduce
temperature changes due to external causes.
Referring back to FIG. 4, the lower shelf 29 along with one of
a plurality of upper shelves 30 (others not shown) are illustrated.
The use of the two-part panel 27 allows access to the lower panel
27A without disturbing the upper panel 27B of the refrigerated compartment.
Regarding the use of the separate lower panel 27A, this arrangement
allows repair personnel to work on equipment without disassembling
the entire showcase. Thus, the lower panel 27A, which preferably
ends beneath the lower shelf 29, can be removed for access behind
the panel 27 without disturbing any items on display.
A different aspect of the present invention relates to the opening
in the front of the showcase through which a consumer can view and
access foodstuffs on display therein. The foodstuffs in the showcase
are cooled by air introduced from behind the perforated panel 27.
The showcase also includes an air curtain 103 generated within and
directed downwardly at the opening.
The invention also involves a method of developing the parameters
for balancing the relative air flows of coolant air from behind
the perforated panel 27 and from the air curtain 103 to minimize
coolant air loss through the opening. By reference to FIGS. 3 and
4 together, the method involves the following steps in series:
a) as seen in FIG. 4, adjusting the relative flows of the air curtain
103 and the coolant air from behind the panel 27 to maintain the
air curtain 103 in a stable condition;
b) introducing an additive to the circulating air that enables
observation and identification of any air escaping at the vertical
periphery of the front opening; and
c) as seen in FIG. 3, applying lips 51 and 52 to extend from the
edges 53 and 54 of the vertical sides 55 and 56 into the opening
to control the loss of coolant air. This loss occurs at the vertical
periphery of the opening in the refrigerated showcase.
Returning to FIG. 4, the aspect of the invention relating to ameliorating
air loss through the air curtain 103 of the refrigerated showcase
depends upon the arrangement of the enclosure for the display of
the refrigerated foodstuffs. The enclosure has the opening defined
at its top by a top panel 104 and at its bottom by a bottom panel
105. The enclosure further includes the perforated panel 27 through
which coolant air is introduced horizontally into the enclosure
and passed over the foodstuffs. The top panel 104 has, at a forward
part thereof above the front access opening, a channel 108 for forming
the flowing air curtain 103 which flows at a high speed so as to
prevent the coolant air from the perforated panel 27 from breaking
through the access opening. Thus, the slower moving coolant air
is diverted downwardly upon reaching the access opening, as seen
in FIG. 4.
Returning to FIG. 3, the lips 51 and 52, placed on each of the
edges 53 and 54 along the length of the vertically elongated sides
55 and 56, reduce coolant air loss at the sides of the opening.
The lips 51 and 52 preferably extend the entire length of each of
the edges 53 and 54 which form the vertically elongated sides of
the access opening.
Although the principles of the present invention have been illustrated
herein in a particular embodiment for refrigerated showcases, it
is not intended to limit such principles to that particular device
alone, since the same principles are readily applicable to various
other forms of devices. Thus, the principles of the present invention
should be broadly construed and not limited to the specific embodiments
set forth in the appended claims.