U.S. patent application number 13/191896 was filed with the patent office on 2012-02-02 for evaporator with integrated heating element.
Invention is credited to Ye FANG, Roger C. PALMER.
Application Number | 20120023993 13/191896 |
Document ID | / |
Family ID | 45525333 |
Filed Date | 2012-02-02 |
United States Patent
Application |
20120023993 |
Kind Code |
A1 |
PALMER; Roger C. ; et
al. |
February 2, 2012 |
EVAPORATOR WITH INTEGRATED HEATING ELEMENT
Abstract
An evaporator coil includes a conduit having an interior
passageway that provides a pathway for a flow of refrigerant. An
outer wall of the conduit forms a channel having a longitudinal
opening. The channel extends lengthwise adjacent to the interior
passageway. The channel contains an electrical heating element that
is in thermal contact with the conduit. The electrical heating
element periodically provides heat to defrost the evaporator coil
during an evaporator defrost cycle. The electrical heating element
may be coupled directly to the channel or be housed within a second
conduit that is at least partially contained within the
channel.
Inventors: |
PALMER; Roger C.; (Cleveland
Hts., OH) ; FANG; Ye; (Wuxi, CN) |
Family ID: |
45525333 |
Appl. No.: |
13/191896 |
Filed: |
July 27, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61367902 |
Jul 27, 2010 |
|
|
|
Current U.S.
Class: |
62/276 |
Current CPC
Class: |
F28F 1/32 20130101; F28F
1/02 20130101; F28F 17/00 20130101; F28D 1/0477 20130101; F25D
21/08 20130101; F25B 39/02 20130101 |
Class at
Publication: |
62/276 |
International
Class: |
F25D 21/08 20060101
F25D021/08 |
Claims
1. An evaporator coil comprising: a conduit having an interior
passageway that provides a pathway for a flow of refrigerant and an
outer wall that forms a channel having a longitudinal opening, the
channel extending lengthwise adjacent to the interior passageway;
and an electrical heating element in the channel and in thermal
contact with the conduit, the electrical heating element
periodically providing heat to defrost the evaporator coil during
an evaporator defrost cycle.
2. The evaporator coil of claim 1, wherein the electrical heating
element is coupled to the channel.
3. The evaporator coil of claim 2, wherein the electrical heating
element is coupled to the outer wall by a thermally conductive
adhesive or by a weld between the electrical heating element and
the channel.
4. The evaporator coil of claim 1, further comprising a second
conduit at least partially contained within the channel, wherein
the electrical heating element is contained within the second
conduit.
5. The evaporator coil of claim 4, wherein the second conduit has
an outer wall that is contoured to fit in the channel.
6. The system of claim 5, further comprising a medium in the second
conduit that facilitates heat transfer between the electrical
heating element and the second conduit.
7. The evaporator coil of claim 4, wherein the first conduit and
the second conduit are formed from different materials.
8. The evaporator coil of claim 1, wherein the electrical heating
element is a resistive heating element.
9. The evaporator coil of claim 1, wherein the first conduit and
the second conduit are extruded.
10. The evaporator coil of claim 1, wherein the conduit has
longitudinal and curved portions and the channel extends
substantially the full length of the conduit.
11. The evaporator coil of claim 1 in an evaporator that is part of
a refrigeration system having an evaporator defrost cycle, wherein
the evaporator coil has an inlet portion configured to interface
with a first conduit of a refrigeration system, and an outlet
portion configured to interface with a second conduit of a
refrigeration system.
12. The system of claim 11, wherein at least one of the first
conduit of the refrigeration system and the second conduit of the
refrigeration system has a tapered channel that corresponds to one
of the channels in the evaporator coil.
13. The system of claim 12, further comprising a controller that
controls the refrigeration system to alternate between operation of
the refrigeration system and an evaporator defrost cycle.
14. An evaporator coil comprising: a first conduit having an
interior passageway that provides a pathway for a flow of
refrigerant and an outer wall that forms a channel having a
longitudinal opening, the channel extending lengthwise adjacent to
the interior passageway; a second conduit having an interior
passageway that provides a pathway for an electrical heating
element, the second conduit at least partially contained within the
channel of the first conduit; and an electrical heating element in
the second channel, the electrical heating element periodically
providing heat to defrost the evaporator coil during an evaporator
defrost cycle.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of the filing
date of U.S. Provisional Patent Application Ser. No. 61/367,902,
file Jul. 27, 2010, the disclosure of which is incorporated herein
by reference in its entirety.
BACKGROUND
[0002] Heat exchangers serve to transfer heat between thermal
masses. In one heat exchanger configuration, air circulates
adjacent to heat exchanger surfaces that are cooled by a
circulating coolant and the air gives up heat to the coolant. When
temperature of the coolant is low enough, ice may form on the
surfaces and impede heat exchange between the surfaces and the air.
It is desirable to remove such ice with a minimum of added heat,
since a surface that is heated must be re-cooled in order to resume
heat exchange with the air.
[0003] Pulse heating is one method of removing ice build-up from
the evaporator. Pulse heating is a method of melting a boundary
layer of ice between the ice and the refrigerant conduit. In
effect, pulse heating supplies a low voltage current through the
wall of the refrigeration conduit, thereby utilizing the conduit as
a conductor. The conduit is typically made from an inductive
material such as stainless steel, which may be undesirable due to
its weight and expense.
SUMMARY
[0004] The present invention provides an evaporator coil that has
an integrated heating element. When ice builds up on the surfaces
of the evaporator, an evaporator defrost cycle can be initiated in
which heat from the integrated heating element can be used to melt
the ice. Integrating the heating element with the refrigerant
conduit can greatly reduce the heat required to defrost the
evaporator, and can provide lower power defrosts that can be run
with increased frequency and efficiency over other
evaporator/heater arrangements.
[0005] For example, the evaporator disclosed herein may provide
energy and efficiency savings over an evaporator that has a heater
that is spaced from and/or that is in poor thermal contact with the
refrigerant conduit and which typically requires excessive heating
(overheating) to melt ice on the evaporator coil. Additionally, the
evaporator may be less expensive to manufacture, maintain, and
operate than pulse cooling systems.
[0006] According to one aspect, the present invention provides an
evaporator coil having a conduit with an interior passageway that
provides a pathway for a flow of refrigerant. An outer wall of the
conduit forms a channel having a longitudinal opening that extends
lengthwise adjacent to the interior passageway. The channel
contains an electrical heating element that is in thermal contact
with the conduit. The electrical heating element periodically
provides heat to defrost the evaporator coil during an evaporator
defrost cycle.
[0007] According to another aspect, the evaporator coil can include
a second conduit having an interior passageway that provides a
pathway for the electrical heating element. The second conduit can
be at least partially contained within the channel of the first
conduit.
[0008] According to another aspect, the evaporator coil can be part
of an evaporator in a refrigeration system and the system can be
controlled by a controller that alternates between a refrigeration
cycle and the evaporator defrost cycle.
[0009] To the accomplishment of the foregoing and related ends, the
invention comprises the features hereinafter fully described and
particularly pointed out in the claims. The following description
and the annexed drawings set forth in detail certain illustrative
embodiments of the invention. These embodiments are indicative,
however, of but a few of the various ways in which the principles
of the invention may be employed. Other objects, advantages and
novel features of the invention will become apparent from the
following detailed description of the invention when considered in
conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The appended drawings show various features of embodiments
of the invention.
[0011] FIG. 1 is a schematic diagram of a refrigeration system in
accordance with aspects of the invention;
[0012] FIG. 2 is an exemplary evaporator having an integrated
heating element as may be used in the system of FIG. 1;
[0013] FIG. 3A is a perspective view of a segment of an evaporator
coil in accordance with aspects of the invention;
[0014] FIG. 3B is a cross-sectional view of the evaporator coil of
FIG. 3A taken along lines A-A;
[0015] FIG. 4A is a perspective view of a segment of an evaporator
coil in accordance with aspects of the invention;
[0016] FIG. 4B is a cross-sectional view of the evaporator coil of
FIG. 4A taken along lines B-B; and
[0017] FIG. 5 is a detailed view of a transition region between the
evaporator coil and a conduit of the refrigeration system.
DETAILED DESCRIPTION
[0018] Referring to FIG. 1, an exemplary refrigeration system 10 is
shown. A circulating refrigerant enters a compressor 12 as a vapor
and is compressed such that it exits the compressor as a vapor at a
higher temperature. The vapor travels through a condenser 14 which
cools the vapor until it starts condensing into a liquid. The
liquid refrigerant then passes through an expansion valve 16 where
its pressure abruptly decreases, causing flash evaporation of some
of the refrigerant. This results in a mixture of liquid and vapor
at a lower temperature and pressure. The low temperature
liquid-vapor mixture then travels through an evaporator 18. In the
evaporator, the liquid-vapor mixture is completely vaporized by
blowing the warm air from the space to be cooled across the
evaporator coil or tubes. The refrigerant cools the air by removing
the heat, and the resulting vapor refrigerant then returns to the
compressor 12 to complete the cycle. The various components of the
refrigeration system can be connected via one or more conduits
20.
[0019] The system may include a controller 22. The controller 22
can be configured to control the various components of the system
including the compressor, the expansion valve and the evaporator.
For example, the evaporator can be controlled to alternate between
the aforementioned refrigeration cycle and a defrost cycle for
removing ice that may build up on the evaporator. The controller 22
can be coupled to a power supply 24, and can control the flow of
electricity to the evaporator during the evaporator defrost
cycle.
[0020] The evaporator 18 can take a variety of forms. For example,
the evaporator 18 may be a tube evaporator with fins, a coiled
evaporator, a flat evaporator, a bottle brush evaporator, etc. FIG.
2 shows one exemplary embodiment of an evaporator 18 having a coil
26 that has a plurality of longitudinal sections 28 and curved
sections 30. The evaporator coil 26 has an inlet portion 32
configured to interface with a conduit 20 of a refrigeration system
10, and an outlet portion 34 configured to interface with another
conduit 20 of the refrigeration system 10. The evaporator 18 has an
integrated heating element 36 for defrosting the evaporator during
an evaporator defrost cycle. Further, the inlet portion 32 and
outlet portion 34 may include a transition region as shown and
described with respect to FIG. 5.
[0021] FIG. 3A shows a segment of an evaporator coil 40 with an
integrated heating element 41, and FIG. 3B shows a cross-sectional
view of the evaporator coil 40 taken along lines A-A. The
evaporator coil 40 includes a conduit 42 having an inner wall 44
and an outer wall 46. The inner wall 44 defines an interior
passageway 48 that provides a pathway for a flow of
refrigerant.
[0022] A channel 50 is formed by one or more portions 52 of the
outer wall 46. As shown in FIG. 3A, the channel 50 extends
lengthwise along the evaporator coil adjacent to the interior
passageway 48 and has a longitudinal opening. The channel 50 may
extend parallel to a central axis of the interior passageway 48.
Alternatively, the channel may be angled relative to the central
axis of the interior passageway 48, for example, the channel 50 may
extend helically about the center axis of the interior passageway
48 as it extends along a length of the outer wall.
[0023] The channel 50 may consume a relatively small portion of the
interior passageway 48. In the exemplary embodiment of FIGS. 3A and
3B, the channel 50 is in the general shape of a "V", however, the
channel may have a different shape. For example, the channel may
have a "U" shape, a "C" shape, a curve shape or another shape.
[0024] The heating element 41 is integrated into the evaporator 18.
The heating element 41 is at least partially contained within the
channel 50. In the illustrated embodiment, the heating element 41
is completely contained within the channel 50. The heating element
41 may be a resistive heating element and may be coupled to a low
voltage power source, for example, a 120-volt or 220-volt power
source. In one embodiment, the heating element 41 is an electric
heating cable (e.g., an insulated wire).
[0025] The heating element 41 is in thermal contact with the
conduit 42 via the portions 52 of the outer wall 46 that form the
channel 50. The heating element 41 can be in direct physical
contact with the portions 52 of the outer wall 46 that form the
channel 50, or alternatively, the heating element 41 can be held in
thermal and/or physical contact with the channel 50 by a thermally
conductive material 56, such as a thermally conductive adhesive.
Alternatively, the heating element 41 may be welded directly to the
channel 50 or held in place by a retaining element such as a strap
or other mechanical implement. As shown in FIGS. 4A and 4B and
described below, the heating element also can be contained in a
separate conduit that is coupled to the channel.
[0026] The heating element 41 can be controlled (e.g., manually
controlled or automatically controlled with the controller 22) to
provide heat to defrost the surfaces of the evaporator 18,
including the outer wall 46 of the conduit 42, during the
evaporator defrost cycle. The controller 22 can be programmed or
otherwise configured to periodically enter an evaporator defrost
cycle in which the refrigeration cycle is stopped and electricity
is provided to the heating element 41. As used herein, periodically
can mean regular or irregular time intervals. For example, the
system can be configured to enter the defrost cycle on a regular
basis such as hourly, twice a day, daily, or at any combination of
regular or irregular time intervals.
[0027] Additionally or alternatively, the evaporator can be
configured to enter the defrost cycle whenever a buildup of ice is
detected by sensors or other feedback mechanisms in the system,
such as sensor 54 that may be operatively coupled to the controller
22. The system may include functionality to allow an operator to
manually switch the system to the defrost mode.
[0028] Referring to FIGS. 4A and 4B, another embodiment of an
evaporator coil 70, with an integrated heating element 90 is shown.
The evaporator coil 70 includes a conduit 72 having an inner wall
74 and an outer wall 76. The inner wall 74 defines an interior
passageway 78 that provides a pathway for a flow of refrigerant.
One or more portions 80 of the outer wall 76 form a channel 82 that
extends longitudinally along the evaporator coil 70 adjacent to the
interior passageway 78. The channel 82 has a longitudinal opening.
As noted above, the channel 82 need not be parallel to the axis of
the passageway 78.
[0029] A second conduit 84 is coupled to the first conduit 72 at
the channel 82. The second conduit 84 has an inner wall 86 that
provides a passageway 88 for the heating element 90 as described
above with respect to FIGS. 3A and 3B. The heating element 90 is
shown in the illustrated embodiment as being spaced from the inner
wall 86 of the passageway 88, however, the heating element may be
in contact with the inner wall 86, which can improve the efficiency
of the heat transfer for defrosting the evaporator. Additionally or
alternatively, the second conduit 84 may be filled with a medium to
aid heat transfer between the conduit and the heating element. For
example, the second conduit 84 may be filled with grease or another
medium, such as a gas or liquid. The second conduit 84 may provide
physical and environmental protection for the heating element
90.
[0030] The second conduit 84 has an outer wall 92. Portions 94 of
the outer wall 92 are shaped to substantially match the contour of
the channel 82 formed by portions 80 of the outer wall 76 of the
first conduit 72. The second conduit 84 is at least partially
contained within the channel 82 and an interface is formed between
the portions 80 of the outer wall 76 of the first conduit 72 and
portions 94 of the outer wall 92 of the second conduit 84. As shown
best in FIG. 4B, the shape of the channel 82 and the shape of the
portions 94 of the outer wall 92 of the second conduit 84 can be
complementary to one another, with the first conduit 72 and the
second conduit 84 fitting together. As shown in FIG. 4B, the
conduits 72 and 84 can form an evaporator coil with an integrated
heating element that has a substantially circular cross-sectional
shape.
[0031] The conduits may be coupled and held together by an
adhesive, weld, or other type of attachment. Alternatively, the
conduits may be integrally formed with one another, for example, by
coextruding the conduits. The conduits may be formed from the same
or different materials. Some exemplary suitable materials include
aluminum, copper, stainless steel, and the like.
[0032] An advantage of the evaporator coil disclosed herein is that
it can be used to defrost an evaporator without using the
evaporator coil as a conductor to melt the boundary layer of ice on
the evaporator coil. Accordingly, the evaporator can be formed from
cheaper materials, which may provide a cost and/or weight savings.
Additionally, an evaporator with the evaporator coil disclosed
herein can be have a defrost cycle without complicated and
expensive electronics, such as transformers and the like.
[0033] FIG. 6 shows an exemplary embodiment of a transition region
100 between an evaporator coil 102 and a conduit 104 of a
refrigeration system (e.g., refrigeration system 10). The conduit
104 has a channel 106 that is aligned with channel 108 in the
evaporator coil 102. The conduit channel 106 may be tapered such
that the channel 106 is deeper at the end 110 that is connected to
the evaporator coil 102. The tapered channel can facilitate
assembly and integration of the heating element into the evaporator
coil and/or may provide an area to connect the heating element to a
power supply or controller. The evaporator coil 102 and conduit 104
may be welded at the interface and may be made from different
materials (e.g., the evaporator coil may be formed from aluminum
and the conduit may be formed from copper).
[0034] Although the principles, embodiments and operation of the
present invention have been described in detail herein, this is not
to be construed as being limited to the particular illustrative
forms disclosed. They will thus become apparent to those skilled in
the art that various modifications of the embodiments herein can be
made without departing from the spirit or scope of the
invention.
* * * * *