U.S. patent application number 10/689600 was filed with the patent office on 2005-04-28 for cooling mechanism for refrigeration systems.
Invention is credited to Lalumiere, Rejean, Letourneau, Bruno.
Application Number | 20050086965 10/689600 |
Document ID | / |
Family ID | 34701697 |
Filed Date | 2005-04-28 |
United States Patent
Application |
20050086965 |
Kind Code |
A1 |
Lalumiere, Rejean ; et
al. |
April 28, 2005 |
Cooling mechanism for refrigeration systems
Abstract
An evaporator is provided having first and second independent
evaporator coils. The evaporator is for use in a refrigerated
display case, either open or closed, having a display length. Each
of the evaporator coils is co-extensive along the display length.
The evaporator coils are alternately defrosted and cooled in such a
manner as to maintain a substantially constant cooling temperature
throughout the refrigerated display case, even during a defrost
cycle. An independent set of cooling fins is mounted to each of the
evaporator coils for absorbing heat when a refrigerant, either
liquid or gas, is circulated and evaporates in the evaporator
coils, thus cooling the display case. A separate return is provided
for each separate evaporator coil, though the two returns
preferably join into a common return, thereby facilitating
maintenance of a substantially constant cooling temperature.
Inventors: |
Lalumiere, Rejean; (Lacolle,
CA) ; Letourneau, Bruno; (Sainte-Foy, CA) |
Correspondence
Address: |
BORDEN LADNER GERVAIS LLP
WORLD EXCHANGE PLAZA
100 QUEEN STREET SUITE 1100
OTTAWA
ON
K1P 1J9
CA
|
Family ID: |
34701697 |
Appl. No.: |
10/689600 |
Filed: |
October 22, 2003 |
Current U.S.
Class: |
62/277 ;
62/525 |
Current CPC
Class: |
F28D 1/0477 20130101;
F25B 2600/2511 20130101; F25B 39/022 20130101; F28D 1/0435
20130101; F28F 2215/02 20130101; F25B 2347/021 20130101; F28F 1/32
20130101; F28F 2009/004 20130101; F25B 47/02 20130101; F25B 2400/22
20130101; F25B 5/00 20130101 |
Class at
Publication: |
062/277 ;
062/525 |
International
Class: |
F25B 047/00; F25B
039/02 |
Claims
What is claimed is:
1. An evaporator for use in a refrigerated display case having a
display length, the evaporator comprising: first and second
independent evaporator coils co-extensive along the display length,
each evaporator coil operable in a cooling cycle and a defrost
cycle in alternating time periods in such a manner as to maintain a
substantially constant cooling temperature throughout the
refrigerated display case, even during a defrost cycle.
2. The evaporator of claim 1 further comprising: first and second
independent sets of cooling fins mounted to the first and second
evaporator coils, respectively, for absorbing heat when a
refrigerant is circulated and evaporates in the evaporator coils,
thus cooling the display case.
3. The evaporator of claim 1 wherein each of the first and second
independent evaporator coils comprises an inlet end for receiving
at least one feed of refrigerant from an independently controlled
distributor line.
4. The evaporator of claim 1 wherein each of the first and second
independent evaporator coils comprises an outlet end for returning
gas refrigerant to a return for subsequent condensation and
recirculation to the evaporator coil from which it originated.
5. The evaporator of claim 1 further comprising: an insulating
member, provided between the first and second independent
evaporator coils, for minimizing effects of a change in temperature
from a defrosting evaporator coil on a non-defrosting evaporator
coil.
6. The evaporator of claim 5 wherein the insulating member is made
of a plastic.
7. The evaporator of claim 5 wherein the insulating member is made
of steel.
8. A cooling system for use in a refrigerated display case having a
display length, the cooling system comprising: an evaporator having
first and second independent evaporator coils co-extensive along
the display length, each evaporator coil operable in a cooling
cycle and a defrost cycle in alternating time periods in such a
manner as to maintain a substantially constant cooling temperature
throughout the refrigerated display case, even during a defrost
cycle; and a common return connected to the first and second
evaporator coils for receiving ambient air to be cooled by the
evaporator.
9. The cooling system of claim 8 further comprising: first and
second flow control valves, in communication with the first and
second independent evaporator coils, respectively, for
independently controlling refrigerant flow to the first and second
independent evaporator coils.
10. The cooling system of claim 9 wherein the first and second flow
control valves are solenoid valves.
11. The cooling system of claim 8 further comprising: first and
second filters, in communication with the first and second
independent evaporator coils, respectively, for independently
preventing impurities from entering into the first and second
independent evaporator coils.
12. The cooling system of claim 8 further comprising: first and
second shutoff valves, in communication with the first and second
independent evaporator coils, respectively, for manually stopping
refrigerant flow to the first and second independent evaporator
coils.
13. The cooling system of claim 8 further comprising: first and
second flow regulating devices, in communication with the first and
second independent evaporator coils, respectively, for regulating
refrigerant flow to the first and second independent evaporator
coils.
14. The cooling system of claim 13 wherein the flow regulating
devices are thermostatic expansion valves.
15. The cooling system of claim 14 wherein the expansion devices
are thermostatic expansion valves.
16. The cooling system of claim 8 further comprising: first and
second distributors, in communication with the first and second
independent evaporator coils, respectively, for equally
distributing refrigerant flow to the first and second independent
evaporator coils.
17. The cooling system of claim 8 further comprising: a controller
for scheduling and controlling the alternating defrost cycles of
the first and second independent evaporator coils.
18. A cooling system for use in a plurality of refrigerated display
cases each having a display length, the cooling system comprising:
a plurality of evaporators connected in parallel, each evaporator
having first and second independent evaporator coils co-extensive
along the display length, each evaporator coil operable in a
cooling cycle and a defrost cycle in alternating time periods in
such a manner as to maintain a substantially constant cooling
temperature throughout the refrigerated display case, even during a
defrost cycle, the first independent evaporator coils of each of
the plurality of evaporators being connected to one another and
defining a set of first evaporator coils, and the second
independent evaporator coils of each of the plurality of
evaporators being connected to one another and defining a set of
second evaporator coils; first and second flow control valves, in
communication with the sets of first and second evaporator coils,
respectively, for independently controlling refrigerant flow to the
sets of first and second evaporator coils; and a common return
connected to the sets of first and second evaporator coils for
receiving ambient air to be cooled by the evaporator.
19. The cooling system of claim 18 wherein the first and second
flow control valves are solenoid valves.
20. A defrosting method for a refrigerated display case having
first and second independent evaporator coils, the evaporator coils
being co-extensive along a display length of the refrigerated
display case, the method comprising: cooling the first and second
independent evaporator coils together; defrosting the first
independent evaporator coil while cooling the second independent
evaporator coil, the second independent evaporator coil
substantially covering the entire length of a display case of the
refrigeration system; cooling the first and second independent
evaporator coils together; and defrosting the second independent
evaporator coil while cooling the first independent evaporator
coil, the first independent evaporator coil substantially covering
the entire length of a display case of the refrigeration system.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to refrigeration
systems. More particularly, the present invention relates to a
cooling mechanism for refrigeration systems.
BACKGROUND OF THE INVENTION
[0002] Refrigeration systems are important to many industries, in
particular the grocery and food industry. Many such systems include
a cooled display area in which products, such as meats, poultry,
etc., can be displayed while kept at a cool temperature to prevent
premature spoilage.
[0003] Most refrigeration systems include one or more evaporators,
each having a single evaporator coil. Those coils are
advantageously defrosted in order to prevent wear of the coils and
prevent the product from getting too cold. Defrosting typically
takes place three or four times daily, often in off-peak time to
the extent it is possible, in order not to disrupt temperature
during shopping hours.
[0004] There are currently three main defrosting methods for
refrigerated display cases. The first method involves unassisted
off-time evaporation/ventilation, where the compressor driving the
evaporator coil is simply turned off for a period of time and the
defrosting is achieved by exposure to the ambient temperature. The
second method uses hot gas-assisted evaporation, where a hot gas is
circulated in the evaporator coil during the defrost cycle in order
to accelerate the defrosting process. The third method uses
electric defrosting, which is similar to the hot-gas-assisted
arrangement, but uses electricity to heat the evaporator coils and
promote defrosting. The first method is slow, while the second and
third methods, although faster, require extra energy to effect the
defrosting.
[0005] After a defrosting cycle, the cooling system in the
refrigerated display case has to re-cool the air in the display
case, so that the products can be re-cooled and kept fresh. The
refrigerated display case is typically kept at a temperature of
about 2 degrees Celsius during a cooling cycle. The temperature of
a display case during a defrost cycle can reach up to 13 degrees
Celsius. Because of that, after defrosting the cooling system has
to work hard to achieve its previous cooled temperature. The system
has to overcome not only the increase in the ambient air
temperature, but also heating that has occurred in the product
being cooled.
[0006] For meats, spoilage is a particular problem for grocery
operators and other vendors. Most financial losses in meat
departments are due to spoilage of meat caused in large part by
defrost cycles, and not because of lack of sales. Since there is a
high profit margin in meat sales, it is important that the quality
of product be maintained. In addition to spoilage, meats are also
subject to shrinkage due to the large proportion of water they
contain. With conventional defrost cycles and their attended large
temperature swings, meats can lose a large amount of their size and
weight, resulting in lost sales for the seller since the meat has
to be re-weighed and repackaged, if it can be salvaged at all.
[0007] Cooling systems are known in which a plurality of
evaporators are provided in a refrigerated display case, and are
divided into groups for cooling different sections of the
refrigerated display case. The evaporators each have a single
evaporator coil. The evaporators are provided in sections laterally
adjacent one another and are defrosted, in their groups, in
alternating staggered cycles. This is done in an attempt to
mitigate some of the drawbacks of defrost cycles as discussed
above. However, during any given defrost cycle according to such
known systems having evaporator groups, the section being defrosted
is still subjected to a significantly higher temperature than the
cooled temperature, thereby increasing the possibility of spoiling
the product in that section. Also, each section typically has a
separate air return system, so that a given section remains hot
during its defrost cycle, despite the fact that the surrounding
sections are being cooled. Moreover, separate evaporators and
compressors must be used in each section, which results in high
energy consumption.
[0008] It is, therefore, desirable to provide a cooling mechanism
for refrigeration systems that can more efficiently cool and
defrost evaporator coils without large temperature swings.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to obviate or
mitigate at least one disadvantage of previous cooling mechanisms
for refrigeration systems.
[0010] In a first aspect, the present invention provides an
evaporator for use in a refrigerated display case having a display
length. The evaporator includes first and second independent
evaporator coils co-extensive along the display length, each
evaporator coil operable in a cooling cycle and a defrost cycle in
alternating time periods in such a manner as to maintain a
substantially constant cooling temperature throughout the
refrigerated display case, even during a defrost cycle.
[0011] In an embodiment, the evaporator further includes first and
second independent sets of cooling fins mounted to the first and
second evaporator coils, respectively, for absorbing heat when a
refrigerant is circulated and evaporates in the evaporator coils,
thus cooling the display case. In another embodiment, the
evaporator further includes an insulating member, which can be made
of a plastic, provided between the first and second independent
evaporator coils, for minimizing effects of a change in temperature
from a defrosting evaporator coil on a non-defrosting evaporator
coil. Each evaporator coil can include an inlet end for receiving
at least one feed of refrigerant from an independently controlled
distributor line. Each evaporator coil can include an outlet end
for returning gas refrigerant to a return for subsequent
condensation and recirculation to the evaporator coil from which it
originated.
[0012] In a further aspect, there is provided a cooling system for
use in a refrigerated display case having a display length. The
cooling system includes an evaporator having first and second
independent evaporator coils co-extensive along the display length,
each evaporator coil operable in a cooling cycle and a defrost
cycle in alternating time periods in such a manner as to maintain a
substantially constant cooling temperature throughout the
refrigerated display case, even during a defrost cycle. The cooling
system also includes a common return connected to the first and
second evaporator coils for receiving ambientair to be cooled by
the evaporator.
[0013] In an embodiment, the cooling system further includes first
and second flow control valves, in communication with the first and
second independent evaporator coils, respectively, for
independently controlling refrigerant flow to the first and second
independent evaporator coils. The cooling system can also include
first and second filters, in communication with the first and
second independent evaporator coils, respectively, for
independently preventing impurities from entering into the first
and second independent evaporator coils. The cooling system can
include first and second shutoff valves, in communication with the
first and second independent evaporator coils, respectively, for
manually stopping refrigerant flow to the first and second
independent evaporator coils. The cooling system can also include
first and second flow regulating devices, in communication with the
first and second independent evaporator coils, respectively, for
regulating refrigerant flow to the first and second independent
evaporator coils. The cooling system can further include first and
second distributors, in communication with the first and second
independent evaporator coils, respectively, for equally
distributing refrigerant flow to the first and second independent
evaporator coils. A controller can also be provided in the cooling
system, for scheduling and controlling the alternating defrost
cycles of the first and second independent evaporator coils.
[0014] In a yet further aspect, there is provided a defrosting
method for a refrigerated display case having first and second
independent evaporator coils, the evaporator coils being
co-extensive along a display length of the refrigerated display
case. The method includes the following steps: cooling the first
and second independent evaporator coils together; defrosting the
first independent evaporator coil while cooling the second
independent evaporator coil, the second independent evaporator coil
substantially covering the entire length of a display case of the
refrigeration system; cooling the first and second independent
evaporator coils together; and defrosting the second independent
evaporator coil while cooling the first independent evaporator
coil, the first independent evaporator coil substantially covering
the entire length of a display case of the refrigeration
system.
[0015] In a still further aspect, there is provided a cooling
system for use in a plurality of refrigerated display cases each
having a display length. The cooling system includes a plurality of
evaporators connected in parallel. Each evaporator has first and
second independent evaporator coils co-extensive along the display
length, with each evaporator coil being operable in a cooling cycle
and a defrost cycle in alternating time periods in such a manner as
to maintain a substantially constant cooling temperature throughout
the refrigerated display case, even during a defrost cycle. The
first evaporator coils of each of the plurality of evaporators are
connected to one another and define a set of first evaporator
coils. The second evaporator coils of each of the plurality of
evaporators are connected to one another and define a set of second
evaporator coils. First and second flow control valves are
provided, in communication with the sets of first and second
evaporator coils, respectively, for independently controlling
refrigerant flow to the sets of first and second sets of evaporator
coils.
[0016] Other aspects and features of the present invention will
become apparent to those ordinarily skilled in the art upon review
of the following description of specific embodiments of the
invention in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Embodiments of the present invention will now be described,
by way of example only, with reference to the attached figures,
wherein:
[0018] FIGS. 1A and 1B are perspective views of conventional
refrigerated display cases;
[0019] FIGS. 2A, 2B and 2C are side, top and end views,
respectively, of a conventional evaporator for use in a
refrigerated display case;
[0020] FIG. 3 is a side view of a known configuration of
evaporators for use in a refrigerated display case;
[0021] FIGS. 4A, 4B and 4C are side, top and end views,
respectively, of an evaporator according to an embodiment of the
present invention for use in a refrigerated display case;
[0022] FIG. 5 is a top view of an evaporator according to another
embodiment of the present invention for use in a refrigerated
display case; and
[0023] FIG. 6 is an evaporator according to an embodiment of the
present invention shown connected to a portion of a refrigeration
system for use in a refrigerated display case.
DETAILED DESCRIPTION
[0024] Generally, the present invention provides an evaporator
having first and second independent evaporator coils. The
evaporator is for use in a refrigerated display case, either open
or closed, having a display length. Each of the evaporator coils is
co-extensive along the display length. The evaporator coils are
alternately defrosted and cooled in such a manner as to maintain a
substantially constant cooling temperature throughout the
refrigerated display case, even during a defrost cycle. An
independent set of cooling fins is mounted to each of the
evaporator coils for absorbing heat when a refrigerant, either
liquid or gas, is circulated and evaporates in the evaporator
coils, thus cooling the display case. A separate return is provided
for each separate evaporator coil, though the two returns
preferably join into a common return, thereby facilitating
maintenance of a substantially constant cooling temperature.
[0025] The present invention preferably provides at least one of
the following advantages over known systems: energy savings; time
savings; better use of energy resources; increased product quality
and product life; less water and vapour on display cases caused by
changing temperature due to defrost cycles, resulting in a more
pleasant shopping experience; and money savings due to decreased
spoilage, meat re-packaging, and time spent rewrapping due to
presence of blood in package from defrosting cycles.
[0026] FIG. 1A is a perspective view of a conventional refrigerated
display case. The refrigerated display case 100 in FIG. 1A has a
display case containing a display area having a single display
shelf 102. The display case 100 is shown with a near set of end
pieces removed in order to better show some of the constituent
parts thereof. An evaporator 104 is located underneath the display
area to provide cooling to the display shelf 102. The evaporator
104 is also connected to a series of inflow and outflow tubes, as
well as to a ventilator, in order to circulate refrigerants through
the evaporator and expel heated air by way of a return.
[0027] FIG. 1B is a perspective view of another conventional
refrigerated display case. FIG. 1B illustrates the fact that a
refrigerated display case 106 can have a plurality of display
shelves 102 in its display area. This advantageously makes better
use of floor space, for example, in a grocery store than a display
case with a single display shelf. It also allows for the display of
similar types of product in the same physical area and provides a
retailer with opportunities to cross-sell different types of
product to a customer.
[0028] FIGS. 2A, 2B and 2C are side, top and end views,
respectively, of a conventional evaporator 108 for use in a
refrigerated display case. In FIG. 2A, the side view shows cooling
fins 110. The fins 110 are mounted to an evaporator coil. The
evaporator coil 112 is a cooling coil, typically comprised of metal
tubing in a snake-like configuration within the evaporator 108 in
order to maximize the surface area available for cooling ambient
air. The evaporator coil is essentially a network of cooling tubes
connected together as a single coil in the evaporator. The fins 110
are for absorbing heat when a refrigerant is circulated and
evaporates in the evaporator coil, thus cooling the display case.
The refrigerant can be a liquid or a gas. The evaporator 108
typically includes a plurality of brackets 114 to which the
evaporator coil and the fins are mounted, in order to provide
structural integrity to the evaporator.
[0029] The top view of FIG. 2B shows a portion of the evaporator
coil 112. FIG. 2B also shows a series of outlet tubes 116 that feed
a single return 118. The return 118 takes heated air (resulting
from circulation of the refrigerant) and returns it to other
portions of the cooling system to be cooled again by the
refrigerant. FIG. 2C shows a plurality of rounded ends of a snaking
evaporator coil. FIG. 2C also shows at the top thereof inlets for
receiving a refrigerant, such as a liquid refrigerant, by means of
a refrigerant line 120. Although only one refrigerant line 120 is
shown, for the sake of simplicity of illustration, there is
typically a refrigerant line 120 connected to each inlet. At the
bottom of FIG. 2C are shown outlet ends for feeding a return 118 or
suction line.
[0030] FIG. 3 is a side view of a known configuration of
evaporators for use in a refrigerated display case. In FIG. 3, the
evaporators are identical. However, the evaporators are provided
and controlled in defrost groups. Evaporators 122 are in a first
defrost group, and evaporators 124 and 126 are in a second and
third defrost groups, respectively. Evaporators are provided
laterally adjacent one another and are defrosted in groups in
alternating staggered cycles, so that evaporators immediately
adjacent one another are not simultaneously defrosted. For example,
the first defrost group is defrosted, then the second defrost
group, then the third.
[0031] However, during any given defrost cycle, the sections being
defrosted are still subjected to a significantly higher temperature
than the cooled temperature, thereby increasing the possibility of
spoiling the product in that section. Also, each section has a
separate air return system, so that a given section remains hot
during its defrost cycle, despite the fact that the surrounding
sections are being cooled.
[0032] FIGS. 4A, 4B and 4C are side, top and end views,
respectively, of an evaporator 128 according to an embodiment of
the present invention for use in a refrigerated display case. In
FIG. 4A, the side view is generally similar to that of FIG. 2A.
However, the evaporator 128 according to an embodiment of the
present invention includes first and second independent evaporator
coils, 130 and 132 co-extensive along the display length, i.e. each
substantially covering an entire length of the display counter.
Each of the independent evaporator coils 130 and 132 is operable in
a cooling cycle and a defrost cycle in alternating time periods in
such a manner as to maintain a substantially constant cooling
temperature throughout the display case of the refrigeration
system, even during a defrost cycle. The evaporator coils 130 and
132 are independently-controlled, as will be described later. Only
the evaporator coil 130 is visible in FIG. 4A since the evaporator
coil 132 is lined up directly behind the evaporator coil 130. Each
evaporator coil comprises a plurality of interconnected evaporator
coil tubes. Such an evaporator coil is also known as a
multi-circuit evaporator coil. Each tube is preferably made of a
copper-aluminum composite material. The use of copper prevents the
fins from moving during cooling and defrosting cycles, as opposed
to simply using aluminum alone. The aluminum is used in the
composite since it is thin and easy to work with.
[0033] In a particular example of the invention that was
implemented, each evaporator coil 130 and 132 includes 24 tubes of
copper pipe, for a total of 48 tubes in the evaporator. In known
systems, 48 tubes were provided in the evaporator, but all being
controlled as a single unit. In some known systems, as discussed
earlier, different evaporators were provided in adjacent groups,
which were each separately controlled. However, that separate
control did not eliminate the fact that when one of the groups of
evaporators was being defrosted, the product in the section being
defrosted underwent significant warming.
[0034] Each of the first and second evaporator coils, 130 and 132,
has at least one inlet end 134 and 136, respectively. Each inlet
end 134 and 136 is for receiving at least one feed of refrigerant
from an independently controlled distributor line. The refrigerant
can be any suitable liquid or gas refrigerant, such as freon or
glycol. Each of the first and second independent evaporator coils
comprises an outlet end 138 and 140, respectively, such as returns
or suction lines. Each outlet end 138 and 140 is for returning gas
refrigerant to a return for subsequent condensation and
recirculation to the evaporator coil from which it originated.
These inlet and outlet ends will be further described in relation
to FIG. 6.
[0035] When using an evaporator 128 according to an embodiment of
the present invention, air circulates along the entire length of
the display case through a common return, which is fed by outlets
138 and 140. In known systems, each separate cooling section has
its own return that doesn't mix with the other air. So, if a
section is defrosted in the known systems, the ambient cooling air
increases dramatically in temperature. According to embodiments of
the present invention, because the return is common along the
entire length of the display case, the cooling temperature can more
easily be maintained.
[0036] In FIG. 4B, the independent nature and separation of the two
evaporator coils 130 and 132 is readily apparent. Essentially,
embodiments of the present invention provide the equivalent of two
independent evaporators in the same physical casing. The evaporator
128 also includes first and second independent sets of cooling fins
142 and 144 mounted to the first and second evaporator coils 130
and 132, respectively. Each set of cooling fins 142 and 144 is for
absorbing heat when a refrigerant is circulated and evaporates in
the evaporator coil, thus cooling the display case. Once again, at
the right hand side of the figure are shown the two separate sets
of evaporator coils 130 and 132. At the left hand side are shown
two separate sets of inflow lines. In FIG. 4C, the independent
nature of the two evaporator coils 130 and 132 is illustrated,
highlighted by the gap in between the two coils, which is in
contrast to FIG. 2C, where the evaporator has one long
interconnected coil.
[0037] FIG. 5 is a top view of an evaporator according to another
embodiment of the present invention for use in a refrigerated
display case. Since FIG. 5 is very similar to FIG. 4B, the common
features will not be discussed. In the particular embodiment of
FIG. 5, the evaporator 128 can include an insulating member 146 for
isolating the first and second evaporator coils 130 and 132 from
each other. The insulating member 146 can be, for example, made of
a plastic, steel, or any other suitable material that can be used
to isolate the two evaporator coils from each other, and prevent
changes in one coil from having an effect on the other coil. The
insulating member 146 can be placed between the two evaporator
coils, as illustrated in FIG. 5. The insulating member is provided
as an insulator in order to minimize the effects of the change in
temperature from a defrosting evaporator coil on a non-defrosting
evaporator coil. The insulating member can also minimize the risk
of moisture dropping from a defrosting evaporator coil to a
non-defrosting evaporator coil. Although the insulating member 146
is shown in FIG. 5 as covering the entire length of the evaporator
128, this is only a preferred embodiment. Sufficient isolation, or
insulation, can be provided with the insulating member 146 only
covering a portion of the length of the evaporator.
[0038] FIG. 6 illustrates a cooling system including an evaporator
according to an embodiment of the present invention shown connected
to a portion of a refrigeration system for use in a refrigerated
display case. In FIG. 6 the evaporator 128 receives an input from
two separate feedings networks. The first evaporator coil 130
receives an input at inlet 134 from a refrigerant line controlled
by a flow control valve, such as a solenoid valve, or solenoid,
146. The second evaporator coil 132 receives an input at inlet 136
from a refrigerant line controlled by another solenoid valve 148.
Each flow control valve, or solenoid valve, in this arrangement
acts mainly as a flow control device to control the flow of
refrigerant in a refrigerant line, primarily to prevent flow into
the evaporator during the defrost cycle, or off-cycle. Essentially,
the first and second flow control valves are in communication with
the first and second independent evaporator coils, respectively,
for independently controlling refrigerant flow to the first and
second independent evaporator coils. Solenoid valves are available
for different applications and specifications, such as from the
Sporlan Valve Company of Washington, Mo.
[0039] In between the refrigerant line inflow end and each of the
solenoid valves 146 and 148, a filter 150 can optionally be
provided. The filter 150, typically a copper filter with some sort
of microscopic grill, is provided to prevent impurities from
entering into the evaporator. These impurities can be inherent from
the evaporator coil piping itself, or may have been introduced at
the time of installation. The filter 150 can therefore be
considered almost as a type of insurance against improper
installation. Most of the impurities can generally be filtered out
in the first few hours or days of operation, but the filter 150 can
be advantageously kept in place to continue its filtering job.
Essentially, the first and second filters are in communication with
the first and second independent evaporator coils, respectively,
for independently preventing impurities from entering into the
first and second independent evaporator coils.
[0040] Shutoff valves 152 and 154 can be placed between the filter
and the inflow of the refrigerant line in order to provide a means
by which the flow of refrigerant can be manually stopped in case of
a need for repair or other such situation. The shut off valve is
basically a service access valve, used in case of a problem. The
provision of these separate shutoff valves provides the ability to
service one evaporator coil in the evaporator while the other
evaporator coil can remain operational, thereby still cooling the
display case. Essentially, the first and second shutoff valves are
in communication with the first and second independent evaporator
coils, respectively, for manually stopping refrigerant flow to the
first and second independent evaporator coils. Of course, if no
filter is provided, each shutoff valve is placed between the inflow
of the refrigerant line and the solenoid.
[0041] A flow regulating device, such as a thermostatic expansion
valve 156 and 158, or TEV or TX valve, can be provided between each
solenoid and evaporator coil. The TX valves regulate refrigerant
flow into the evaporator. The flow regulating device is generally
an expansion device if a liquid is used, but can alternatively be
any other type of flow regulating device. The TX valve, or
expansion valve, controls the rate of refrigerant passed into the
system. It can be modulated depending on situational demand (i.e.
measured value compared to desired value). Essentially, the first
and second flow regulating devices are in communication with the
first and second independent evaporator coils, respectively, for
regulating refrigerant flow to the first and second independent
evaporator coils.
[0042] A 1-to-2 distributor can also provided between the flow
regulating device and the evaporator coil, for equally distributing
refrigerant flow from the flow regulating device into each circuit,
or portion, of the evaporator coil. In this example, each
distributor 160, 162 splits the refrigerant line into two lines,
for feeding an inlet 134, 136, respectively. Each distributor can
be connected to the outlet of a TEV, with the outlet of the
distributor preferably being machined to accept tubing which
connects the distributor to each evaporator coil circuit.
Essentially, the first and second distributors are in communication
with the first and second independent evaporator coils,
respectively, for equally distributing refrigerant flow to the
first and second independent evaporator coils. Expansion devices
and distributors are available for different applications and
specifications, such as from the Sporlan Valve Company of
Washington, Mo.
[0043] Embodiments of the present invention can be used together in
an advantageous manner. A plurality of evaporators according to an
embodiment of the present invention can be connected to each other
in parallel. This is advantageous, for example, in a grocery store
where a plurality of refrigerated display cases are placed adjacent
each other. Each of these evaporators has a first and second
independently-controlled evaporator coil. However, when the
evaporators are connected in parallel, the first evaporator coils
of each evaporator are connected together. Similarly, the second
evaporator coil of each evaporator are connected together. The
plurality of evaporators are controlled by a single pair of flow
control valves, such as solenoid valves, i.e. a first solenoid
valve and a second solenoid valve. This advantageously allows a
plurality of evaporators according to an embodiment of the present
invention, and therefore a plurality of refrigerated counters in
which they can be placed, to be centrally controlled by a single
pair of solenoid valves. This is advantageous as compared to
currently known systems, in which a separate solenoid is required
for each evaporator, or refrigerated display case. Therefore,
savings in both cost and complexity are realized according to
embodiments of the present invention.
[0044] In other words, according to an embodiment of the present
invention, a cooling system is provided for use in a plurality of
refrigerated display cases each having a display length. The
cooling system includes a plurality of evaporators connected in
parallel. Each evaporator has first and second independent
evaporator coils co-extensive along the display length, with each
evaporator coil being operable in a cooling cycle and a defrost
cycle in alternating time periods in such a manner as to maintain a
substantially constant cooling temperature throughout the
refrigerated display case, even during a defrost cycle. The first
evaporator coils of each of the plurality of evaporators are
connected to one another and define a set of first evaporator
coils. The second evaporator coils of each of the plurality of
evaporators are connected to one another and define a set of second
evaporator coils. First and second flow control valves are
provided, in communication with the sets of first and second
evaporator coils, respectively, for independently controlling
refrigerant flow to the sets of first and second sets of evaporator
coils. The cooling system can also include a common return
connected to the sets of first and second evaporator coils for
receiving ambient air to be cooled by the evaporator, but this is
only a preferred feature.
[0045] In the cooling system described above, the display length of
each refrigerated display case need not be the same. If the display
cases have a different display length, then the independent
evaporator coils for each refrigerated display case will be
co-extensive along the display length for that particular
refrigerated display case.
[0046] Although not illustrated in FIG. 6, a cooling system
according to an embodiment of the present invention preferably
includes a controller, such as a time clock, timing system, or
other such device. The controller is in communication with the
solenoid valves 146 and 148 for scheduling and controlling the
alternating defrosting of the evaporator coils. Note that
alternatively, the solenoid valves, or flow control valves, can be
manually controlled. The controller is preferably used to implement
a defrosting method in four stages, as follows.
[0047] Stage 1: When the controller initiates a defrost, the
solenoid valve 146 closes, thereby inhibiting any refrigerant from
circulating in the evaporator coil 130. Solenoid 148 stays open and
the fans still operate. The evaporator coil 132 will be defrosting
while the evaporator coil 130 still refrigerates. Keep in mind that
the evaporator coil 130 substantially covers the entire length of a
display case of the refrigeration system, and therefore the display
area of the display case remains uniformly cooled even during the
defrosting of the evaporator coil 132.
[0048] Stage 2: At the conclusion of stage 1 of the defrost cycle,
solenoid valve 146 will reopen. At that time, both of the
evaporator coils 130 and 132 are in a refrigerating mode.
[0049] Stage 3: After a predetermined amount of time, e.g. two
hours after the initiation of stage 1, the controller initiates a
second defrost. At that time, solenoid valve 148 will close and no
more refrigerant will circulate in the evaporator coil 132.
Solenoid 146 stays open and the fans still operate. The evaporator
coil 132 will be defrosting while the evaporator coil 130 still
refrigerates. Keep in mind that the evaporator coil 130
substantially covers the entire length of a display case of the
refrigeration system, and therefore the display area of the display
case remains uniformly cooled even during the defrosting of the
evaporator coil 132.
[0050] Stage 4: At the conclusion of stage 3 of the defrost cycle,
solenoid valve 148 will reopen. At that time, both of the
evaporator coils 130 and 132 are in a refrigerating mode.
[0051] The cycle of stages 1-4 preferably continues over a
twenty-four hour period. The actual amount of time spent defrosting
each evaporator coil and spent with both evaporator coils in the
refrigerating mode can be varied. Although there is no need to
perform the defrosting steps in off-peak times, this can be done if
desired.
[0052] Although there are some known methods in which coils are
alternatingly defrosted, this is known only in the context of
alternatingly defrosting separate evaporators in a series
evaporators placed adjacent one another. There is no known method
in which evaporator coils in the same evaporator are alternatingly
cooled and defrosted. Moreover, in the known methods, there is no
provision for at least one of the evaporator coils covering the
entire surface area to be cooled in order to maintain a
substantially constant cooling temperature, even during defrosting
of one of the evaporator coils.
[0053] The cooling system can optionally include a
temperature/pressure regulator for regulating the temperature
and/or pressure in the cooling system. The cooling system can
further optionally include a data recording unit, which records
temperature readings of the display case on a computer or any other
means. The data recording unit can automatically alert an operator
when the temperature goes below a defined threshold.
[0054] Embodiments of the present invention can be used in both
open refrigerated display cases, as well as closed refrigerated
display cases. Also, the refrigerant used can be a liquid or a gas,
such as freon or glycol.
[0055] The above-described embodiments of the present invention are
intended to be examples only. Alterations, modifications and
variations may be effected to the particular embodiments by those
of skill in the art without departing from the scope of the
invention, which is defined solely by the claims appended
hereto.
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