U.S. patent application number 17/451594 was filed with the patent office on 2022-04-28 for heat transfer tube for heat pump application.
The applicant listed for this patent is Carrier Corporation. Invention is credited to Luis F. Avila, Thomas Bryant, Duane V. Douglas, Robert A. Leffler, Louis J. Sullivan, Thomas Visalli, Ron A. Wilson.
Application Number | 20220128318 17/451594 |
Document ID | / |
Family ID | |
Filed Date | 2022-04-28 |
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United States Patent
Application |
20220128318 |
Kind Code |
A1 |
Leffler; Robert A. ; et
al. |
April 28, 2022 |
HEAT TRANSFER TUBE FOR HEAT PUMP APPLICATION
Abstract
A heat transfer tube and a heat exchanger incorporating at least
one heat transfer tubes are provided. The heat transfer tube and
the heat exchanger are configured to operate in both a heating mode
and a cooling mode (e.g., to optimize the reversible function a
heat pump). The heat transfer tube includes a tube body with an
interior surface and an exterior surface. The tube body defining an
outer diameter (D.sub.o) and a wall thickness (W.sub.T), wherein a
ratio (W.sub.T/D.sub.o) the wall thickness (W.sub.T) to the outer
diameter (D.sub.o) is between 0.061 and 0.071. The heat transfer
tube includes a plurality of adjacent helical fins protruding
circumferentially around the interior surface of the tube body, and
at least one groove disposed between the plurality of adjacent
helical fins. The configuration of the heat transfer tube(s) is
optimal for the reversible function of the heat pump.
Inventors: |
Leffler; Robert A.; (Boston,
MA) ; Visalli; Thomas; (Oneida, NY) ; Avila;
Luis F.; (Manlius, NY) ; Bryant; Thomas;
(Brewerton, NY) ; Douglas; Duane V.;
(Indianapolis, IN) ; Wilson; Ron A.; (Greenwood,
IN) ; Sullivan; Louis J.; (Indianapolis, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Carrier Corporation |
Palm Beach Gardens |
FL |
US |
|
|
Appl. No.: |
17/451594 |
Filed: |
October 20, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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63198577 |
Oct 28, 2020 |
|
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International
Class: |
F28F 1/10 20060101
F28F001/10; F28F 1/40 20060101 F28F001/40; F28F 21/08 20060101
F28F021/08 |
Claims
1. A heat transfer tube for operating in both a heating mode and a
cooling mode, the heat transfer tube comprising: a tube body
comprising an interior surface and an exterior surface, the tube
body defining an outer diameter (D.sub.o) and a wall thickness
(W.sub.T), wherein a ratio (W.sub.T/D.sub.o) of the wall thickness
(W.sub.T) to the outer diameter (D.sub.o) is between 0.061 and
0.071; and a plurality of adjacent helical fins protruding
circumferentially around the interior surface of the tube body, at
least one groove disposed between the plurality of adjacent helical
fins, each respective groove defining a groove width, each
respective helical fin defining a fin height, a fin tip width, a
fin base width, a fin apex angle, and a fin helix angle, wherein
the interior surface of the tube body further comprises a non-fin
weld area, the non-fin weld area defining a non-fin height and a
non-fin width.
2. The heat transfer tube of claim 1, wherein the heat transfer
tube provides a Cavallini factor between 1.67 and 2.22.
3. The heat transfer tube of claim 1, wherein the tube body is
comprised of at least one of: an aluminum and an aluminum
alloy.
4. The heat transfer tube of claim 1, wherein a cross-section of
the heat transfer tube defines between 41 and 48 helical fins.
5. The heat transfer tube of claim 1, wherein the outside diameter
is between 6.85 mm and 7.14 mm.
6. The heat transfer tube of claim 1, wherein the wall thickness is
between 0.410 mm and 0.510 mm.
7. The heat transfer tube of claim 1, wherein the fin height is
between 0.144 mm and 0.248 mm.
8. The heat transfer tube of claim 1, wherein the fin tip width is
between 0.096 mm and 0.156 mm.
9. The heat transfer tube of claim 1, wherein the fin base width is
between 0.18 mm and 0.24 mm.
10. The heat transfer tube of claim 1, wherein the fin apex angle
is between 19.degree. and 35.degree..
11. The heat transfer tube of claim 1, wherein the fin helix angle
is between 13.degree. and 23.degree..
12. The heat transfer tube of claim 1, wherein the groove width is
between 0.102 mm and 0.221 mm.
13. A heat exchanger for operating in both a heating mode and a
cooling mode, the heat exchanger comprising: a plurality of fins;
and at least one heat transfer tube configured to pass a fluid
therethrough, the at least one heat transfer tube extending through
the plurality of fins, each respective heat transfer tube
comprising: a tube body comprising an interior surface and an
exterior surface, the tube body defining an outer diameter
(D.sub.o) and a wall thickness (W.sub.T), wherein a ratio
(W.sub.T/D.sub.o) the wall thickness (W.sub.T) to the outer
diameter (D.sub.o) is between 0.061 and 0.071; and a plurality of
adjacent helical fins protruding circumferentially around the
interior surface of the tube body, at least one groove disposed
between the plurality of adjacent helical fins, each respective
groove defining a groove width, each respective helical fin
defining a fin height, a fin tip width, a fin base width, a fin
apex angle, and a fin helix angle, wherein the interior surface of
the tube body further comprises a non-fin weld area, the non-fin
weld area defining a non-fin height and a non-fin width.
14. The heat exchanger of claim 13, wherein the heat transfer tube
provides a Cavallini factor between 1.67 and 2.22.
15. The heat exchanger of claim 13, wherein the tube body is
comprised of at least one of: an aluminum and an aluminum
alloy.
16. The heat exchanger of claim 13, wherein a cross-section of the
heat transfer tube defines between 41 and 48 helical fins.
17. The heat exchanger of claim 13, wherein the outside diameter is
between 6.85 mm and 7.14 mm, and the wall thickness is between
0.410 mm and 0.510 mm.
18. The heat exchanger of claim 13, wherein the fin height is
between 0.144 mm and 0.248 mm, the fin tip width is between 0.096
mm and 0.156 mm, and the fin base width is between 0.18 mm and 0.24
mm.
19. The heat exchanger of claim 13, wherein the fin apex angle is
between 19.degree. and 35.degree., and the fin helix angle is
between 13.degree. and 23.degree..
20. The heat exchanger of claim 13, wherein the groove width is
between 0.102 mm and 0.221 mm.
Description
CROSS REFERENCE TO A RELATED APPLICATION
[0001] The application claims the benefit of U.S. Provisional
Application No. 63/198,577 filed Oct. 28, 2020, the contents of
which are hereby incorporated in their entirety.
BACKGROUND
[0002] The invention relates generally to heat transfer tubes for
use in heat exchangers. In particular, the invention relates to a
heat transfer tube that is configured to optimize its use within a
heat exchanger for a heat pump, which is capable of operating in a
reversible manner (i.e., able to switch between a heating mode and
a cooling mode).
[0003] A heat pump is a type of is a type of vapor compression
system that is capable of reversing the flow of refrigerant. Vapor
compression systems (e.g., heat pumps) commonly include a
compressor to both move and increase the pressure of the
refrigerant, two heat exchangers (one indoor heat exchanger and one
outdoor heat exchanger) to transfer heat to or from the
refrigerant, and at least one expansion valve for regulating the
flow of refrigerant. To make it possible for the heat pump to
change the direction the refrigerant flows, heat pumps also
commonly include a reversing valve. In a basic heat pump, the
compressor compresses the refrigerant and delivers it downstream
through the reversing valve, which delivers the refrigerant to the
outdoor heat exchanger if the heat pump is operating in a cooling
mode, or to the indoor heat exchanger if the heat pump is operating
in a heating mode. When operating in a cooling mode, the
refrigerant is passed from the outdoor heat exchanger through the
expansion valve to the indoor heat exchanger. When operating in a
heating mode, the refrigerant is passed from the indoor heat
exchanger through the expansion valve to the outdoor heat
exchanger. Regardless of whether in a heating mode or a cooling
mode, the refrigerant is routed back through the reversing valve
back into the compressor, completing the cycle.
[0004] In recent years, there has been a focus on improving the
heat exchangers (both the indoor heat exchanger and the outdoor
heat exchanger) to increase the efficiency of the heat pumps.
Commonly, heat exchangers incorporate one or more tubes to
circulate refrigerant and transfer heat to or from an air supply
(e.g., for a residential home, etc.). This heat is transferred
through the tube walls via conduction. Many heat exchangers also
utilize fins in thermally conductive contact with the outside of
the tubes to provide increased surface area across which heat can
be transferred. To improve the ability of the heat exchanger tubes
to transfer heat through the tube walls, the tubes are often
internally enhanced. These internally enhanced tubes are typically
fabricated via an extrusion or drawings process and mechanically
expanded into the fins to assure good metal-to-metal contact
between the tubes and the fins. Often times copper, or alloys
thereof, are used due to copper's mechanical properties, which
enable helically shaped enhancement profiles to be fabricated with
the extrusion process. However, in recent years, the industry has
started to move from copper to aluminum, primary due to the
fluctuating, often high, price of copper relative to aluminum.
Aluminum, and alloys thereof, have inherently different mechanical
properties that historically have limited its ability to be
manufactured. In addition, due to the properties of the aluminum,
historically, aluminum heat transfer tubes have a thicker tube wall
(relative to tubes made of copper), which causes a smaller internal
diameter, resulting in an increased pressure drop. As such,
selecting an optimal configuration, that is capable of being
manufactured, for an aluminum heat transfer tube often requires a
balance between heat transfer improvement and pressure drop
penalty. Although there are many different configurations of
aluminum heat transfer tubes, new aluminum heat transfer tube
configurations are always welcome.
[0005] Accordingly, there remains an ongoing need for new aluminum
heat transfer tube configurations that are more efficient and
capable of being more easily manufactured.
BRIEF DESCRIPTION
[0006] According to one embodiment, a heat transfer tube for
operating in both a heating mode and a cooling mode is provided.
The heat transfer tube includes a tube body defining an interior
surface and an exterior surface, and a plurality of adjacent
helical fins disposed around the interior surface of the tube body.
The tube body defining an outer diameter (D.sub.o) and a wall
thickness (W.sub.T), wherein a ratio (W.sub.T/D.sub.o) of the wall
thickness (W.sub.T) to the outer diameter (D.sub.o) is between
0.061 and 0.071. The heat transfer tube includes at least one
groove disposed between the plurality of adjacent helical fins.
Each respective groove defines a groove width. Each respective
helical fin defines a fin height, a fin tip width, a fin base
width, a fin apex angle, and a fin helix angle. The interior
surface of the tube body further includes a non-fin weld area, the
non-fin weld area defining a non-fin height and a non-fin
width.
[0007] In accordance with additional or alternative embodiments,
the heat transfer tube provides a Cavallini factor between 1.67 and
2.22.
[0008] In accordance with additional or alternative embodiments,
the tube body is made of at least one of: an aluminum and an
aluminum alloy.
[0009] In accordance with additional or alternative embodiments, a
cross-section of the heat transfer tube defines between 41 and 48
helical fins.
[0010] In accordance with additional or alternative embodiments,
the outside diameter is between 6.85 mm and 7.14 mm.
[0011] In accordance with additional or alternative embodiments,
the wall thickness is between 0.410 mm and 0.510 mm.
[0012] In accordance with additional or alternative embodiments,
the fin height is between 0.144 mm and 0.248 mm.
[0013] In accordance with additional or alternative embodiments,
the fin tip width is between 0.096 mm and 0.156 mm.
[0014] In accordance with additional or alternative embodiments,
the fin base width is between 0.18 mm and 0.24 mm.
[0015] In accordance with additional or alternative embodiments,
the fin apex angle is between 19.degree. and 35.degree..
[0016] In accordance with additional or alternative embodiments,
the fin helix angle is between 13.degree. and 23.degree..
[0017] In accordance with additional or alternative embodiments,
the groove width is between 0.102 mm and 0.221 mm.
[0018] According to another aspect of the disclosure, a heat
exchanger for operating in both a heating mode and a cooling mode
is provided. The heat exchanger includes a plurality of fins and at
least one heat transfer tube configured to pass a fluid
therethrough. The at least one heat transfer tube extending through
the plurality of fins. Each respective heat transfer tube include a
tube body defining an interior surface and an exterior surface, and
a plurality of adjacent helical fins disposed around the interior
surface of the tube body. The tube body defining an outer diameter
(D.sub.o) and a wall thickness (W.sub.T), wherein a ratio
(W.sub.T/D.sub.o) of the wall thickness (W.sub.T) to the outer
diameter (D.sub.o) is between 0.061 and 0.071. The heat transfer
tube includes at least one groove disposed between the plurality of
adjacent helical fins. Each respective groove defines a groove
width. Each respective helical fin defines a fin height, a fin tip
width, a fin base width, a fin apex angle, and a fin helix angle.
The interior surface of the tube body further includes a non-fin
weld area, the non-fin weld area defining a non-fin height and a
non-fin width.
[0019] In accordance with additional or alternative embodiments,
the heat transfer tube provides a Cavallini factor between 1.67 and
2.22.
[0020] In accordance with additional or alternative embodiments,
the tube body is made of at least one of: an aluminum and an
aluminum alloy.
[0021] In accordance with additional or alternative embodiments, a
cross-section of the heat transfer tube defines between 41 and 48
helical fins.
[0022] In accordance with additional or alternative embodiments,
the outside diameter is between 6.85 mm and 7.14 mm, and the wall
thickness is between 0.410 mm and 0.510 mm.
[0023] In accordance with additional or alternative embodiments,
the fin height is between 0.144 mm and 0.248 mm, the fin tip width
is between 0.096 mm and 0.156 mm, and the fin base width is between
0.18 mm and 0.24 mm.
[0024] In accordance with additional or alternative embodiments,
the fin apex angle is between 19.degree. and 35.degree., and the
fin helix angle is between 13.degree. and 23.degree..
[0025] In accordance with additional or alternative embodiments,
the groove width is between 0.102 mm and 0.221 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The subject matter, which is regarded as the disclosure, is
particularly pointed out and distinctly claimed in the claims at
the conclusion of the specification. The following descriptions of
the drawings should not be considered limiting in any way. With
reference to the accompanying drawings, like elements are numbered
alike:
[0027] FIG. 1 is a perspective view of an exemplary heat exchanger
incorporating an exemplary heat exchanger tube, in accordance with
one aspect of the disclosure.
[0028] FIG. 2 is a perspective side view of the exemplary heat
exchanger tube of FIG. 1, in accordance with one aspect of the
disclosure.
[0029] FIG. 3 is a cross-sectional side view of the exemplary heat
exchanger tube of FIGS. 1 and 2 illustrating a plurality adjacent
helical fins protruding circumferentially around the interior
surface of the tube body, in accordance with one aspect of the
disclosure.
[0030] FIG. 4 is a cross-sectional front view of a portion of the
exemplary heat exchanger tube of FIGS. 1-3 illustrating the
plurality of adjacent helical fins from a closer perspective, in
accordance with one aspect of the disclosure.
[0031] FIG. 5 is a cross sectional front view of a portion of the
exemplary heat exchanger tube of FIGS. 1-3 illustrating a non-fin
weld area disposed on the interior surface of the tube body, in
accordance with one aspect of the disclosure.
DETAILED DESCRIPTION
[0032] As will be described below, a heat transfer tube with
improved efficiency and manufacturability, and a heat exchanger
incorporating the same are provided. Specifically, the features of
the heat transfer tube described herein may enable a more efficient
operation for a heat pump, which is capable of operating in both a
heating mode and a cooling mode. The heat transfer tube described
herein has an optimal configuration that balances the heat transfer
improvement (in both condensation and evaporation) with the
associated pressure drop penalty. It was found that the
configuration of the different features of the heat transfer tube
described herein results in a surprisingly high performance when
compared to other designs currently used in the industry. It will
be appreciated that this surprisingly high performance is directly
tied to the use of the heat transfer tube within a heat pump, which
is capable of reversing the flow of refrigerant to switch between a
cooling mode and a heating mode. For example, the heat transfer
tube described herein may not be optimized for use within a system
that is only capable of providing cooling. It will be appreciated
that the heat transfer tube described herein may be made of
aluminum (or alloy thereof), and may only be manufactured using a
welded-rolled formed process (e.g., compared to an extrusion
process commonly used to manufacture heat transfer tubes made of
copper or copper alloys) in certain instances. The manufacturing
process of the heat transfer tube is described in further detail
below. It is envisioned that by manufacturing the heat transfer
tube out of aluminum (or aluminum alloy), instead of copper, that
the associated costs of manufacturing the heat transfer tube may be
more predictable and relatively lower (when compared to heat
transfer tubes made of copper or copper alloys).
[0033] With reference now to the Figures, a perspective view of an
exemplary heat exchanger 200 incorporating an exemplary heat
exchanger tube 100 is shown in FIG. 1. As shown, the heat exchanger
200 may be a round tube plate fin (RTPF) type heat exchanger,
including a plurality of fins 210 and at least one heat transfer
tube 100. For purposes of clarity, although the heat exchanger 200
is shown to include only one heat transfer tube 100, which is shown
to include an inlet line 130 at one end, an outlet line 140
connected at another end, and a bend 150 therebetween, it will be
evident to a person of ordinary skill in the art, that more heat
transfer tubes 100 may be added to the heat exchanger 200. It
should be appreciated that the heat transfer tube 100 may be
separated in multiple sections (e.g., where the bend 150 portion is
connected to the inlet line 130 and the outlet line 140) in certain
instances, or formed as a single tube unitary tube in other
instances.
[0034] As mentioned above, the heat transfer tube(s) 100 may be
made of an aluminum or an aluminum alloy in certain instances. For
example, the heat transfer tube(s) 100 may be made from aluminum
alloys selected from 1000 series, 3000 series, 5000 series, or 600
series aluminum alloys in certain instances. Likewise, the fins 210
too may be made of an aluminum or an aluminum alloy in certain
instances. For example, the fins 210 may be made from aluminum
alloys selected from the 1000 series, 3000 series, 6000 series,
7000 series, or 8000 series aluminum alloys in certain instances.
It will be appreciated that the fins 210 and/or the heat transfer
tube(s) 100 may be made from other aluminum alloys in certain
instances. Regardless of the type of material(s) used to
manufacture the fins 210 and/or the heat transfer tube(s) 100, the
fins 210 may be configured as plate-like elements spaced along the
length of the heat transfer tube(s) 100 (e.g., using an
interference fit in certain instances). As shown in FIG. 1, the
fins 210 may be provided between a pair of end plates or tube
sheets 220, 230. It is envisioned that the fins 210 may help to
increase the surface area for which heat may be transferred between
the refrigerant (circulating through the heat transfer tube(s) 100)
and the air passing over the heat exchanger 200. As mentioned
above, the heat transfer tube(s) 100 may be specifically designed
to increase the efficiency of a heat pump, which is capable of
switching (e.g., by reversing the flow of refrigerant) between a
heating mode and a cooling mode. It will be evident to a person of
ordinary skill in the art, that the heat transfer tube(s) 100 may
not be optimal for use within a system that is only capable of
operating in a cooling mode.
[0035] It will be appreciated that the increase in efficiency of
the heat pump caused by the heat transfer tube(s) is attributable
to the configuration of the different features of the heat transfer
tube(s) 100. An exemplary heat transfer tube 100 is shown in FIGS.
2 and 3. FIG. 2 is provided to illustrate the heat transfer tube
100 without the plurality of fins 200 (as shown in FIG. 1). FIG. 3
is provided to illustrate the interior surface 121 and the exterior
surface 122 of the tube body 120. As shown in FIG. 3, the tube body
120 may define an outer diameter D.sub.o and a wall thickness
W.sub.T. It was found that by controlling the ratio
(W.sub.T/D.sub.o) of the wall thickness W.sub.T to the outer
diameter D.sub.o that the heat transfer tube 100 may be optimized
for use within a heat pump. In certain instances the ratio
(W.sub.T/D.sub.o) of the wall thickness W.sub.T to the outer
diameter D.sub.o is between 0.061 and 0.071.
[0036] As shown in FIG. 3, the heat transfer tube 100 includes a
plurality of adjacent helical fins 110 (shown in FIG. 4) protruding
circumferentially around the interior surface of the tube body 120.
As shown in FIG. 4, at least one groove 160 (viewed as the void or
space between adjacent fins 110) may be disposed between the
plurality of adjacent helical fins 110. Each respective groove may
be viewed to have a defined groove width W.sub.G. Each respective
helical fin 110 may be viewed to have a defined fin height H.sub.F,
fin tip width W.sub.FT, fin base width W.sub.FB, fin apex angle
.THETA..sub.FA, and fin helix angle .THETA..sub.HA (shown in FIG.
3). In addition, the interior surface 121 of the tube body 120 may
also include a non-fin weld area 170 (shown in FIG. 5). It should
be appreciated that this non-fin weld area 170 may be a result of
the welded-rolled formed manufacturing process used to produce the
heat transfer tube 100 described herein. As shown in FIG. 5, the
non-fin weld area 170 may be viewed to have a defined non-fin
height H.sub.NF and non-fin width W.sub.NF.
[0037] As mentioned above, the heat transfer tube 100 described
herein may be manufactured using a welded rolled formed
manufacturing process. This process may include starting with a
rectangular sheet of aluminum (or alloy thereof) that is
manufactured to include fins 110. This rectangular sheet of
aluminum (or alloy thereof) is rolled using a rolling machine into
a tubular shape. These rolling machines may utilize a
high-frequency electrical current to forge the seam or joint of the
heat transfer tube 100. It should be appreciated that other methods
may be used to forge the seam or joint of the heat transfer tube
100 (e.g., tig-type, mig-type, or any suitable electrical-type
welding, etc. may be used in certain instances). The non-fin weld
area 170 described above may be viewed as this seam or joint of the
heat transfer tube 100. Although described as a non-fin weld area
170, it will be appreciated that partial or irregular fins 110 may
be present within the non-fin weld area 170. These partial or
irregular fins 110 may be caused as a result of the welding
process, which may consume or distort the fins 110 from their
original form (i.e. how they existed on the rectangular sheet of
aluminum). It should be appreciated that the dimensions of the
non-fin weld area 170 may be directly associated with the
limitations of the welded rolled formed manufacturing process. For
example, although it may be ideal to minimize the non-fin height
H.sub.NF and/or the non-fin width W.sub.NF in order to maximize the
number of helical fins 110 and/or internal surface area within the
heat transfer tube 100, the welded rolled formed manufacturing
process inherently requires at least a certain sized non-fin weld
area 170. In certain instances the non-fin width W.sub.NF should be
less than 1.4 mm. It should be appreciated that the non-fin weld
area 170 should be ignored with respect to average fin and average
wall thickness W.sub.T in certain instances. It will be evident to
a person of ordinary skill in the art that the non-fin weld area
170 is created a result of a welded rolled formed manufacturing
process and not created by any irregularities from an
extrusion-type manufacturing process.
[0038] As mentioned above, the heat transfer tube 100 described
herein is optimized for use within a heat pump, which is capable of
reversing the flow of refrigerant to switch between a heating mode
and a cooling mode. It was found when optimizing the heat transfer
tube 100 for use within a heat pump the heat transfer tube 100
provides a Cavallini factor between 1.67 and 2.22 in certain
instances. The Cavallini factor may be expressed in terms of the
following formula: [[2*(number of fins)*(height of the
fins)*(1-Sin(.THETA..sub.FA/2))/((3.14)(internal diameter of the
heat transfer tube)*Cos(.THETA..sub.FA/2))+1]/Cos
.THETA..sub.HA]{circumflex over ( )}2. To produce such a heat
transfer tube 100 with such a Cavallini factor, the tube body 120
and the helical fins 110 should be precisely configured. For
example, the cross-section of the heat transfer tube 100 should
define between 41 and 48 helical fins 110 (i.e., when viewed from
the front of the heat transfer tube 100). It will be appreciated
that the heat transfer tube 100 described herein may have 48
helical fins 110 in certain instances.
[0039] It is envisioned that the heat transfer tube 100 described
herein may be configured to minimize its outside diameter D.sub.o
(shown in FIG. 3), while maximizing its internal diameter (i.e.
D.sub.o-W.sub.T), which may help minimize the pressure drop
generated by the heat transfer tube 100. The outside diameter
D.sub.o is between 6.85 mm and 7.14 mm and the wall thickness
W.sub.T (shown in FIG. 4) is between 0.410 mm and 0.510 mm in
certain instances. It will be appreciated that the outside diameter
D.sub.o is less than 7.10 mm (e.g., 7.05 mm) and the wall thickness
W.sub.T is less than 0.50 mm (e.g., 0.46 mm) in certain instances,
which may help minimize the pressure drop generated by the heat
transfer tube 100. To effectively function within the heat pump,
the heat transfer tube 100 should not only be configured to
minimize pressure drop, but should also be configured to maximize
its heat transfer capabilities. As shown above by the formula for
the Cavallini factor, the Cavallini factor (which is illustrative
of the heat transfer capabilities of the heat transfer tube 100) is
dependent, at least in part, on the configuration of the helical
fins 110.
[0040] As shown in FIG. 4, each respective helical fin 110 may be
viewed to have a defined fin height H.sub.F, fin tip width
W.sub.FT, fin base width W.sub.FB, fin apex angle .THETA..sub.FA,
and fin helix angle .THETA..sub.HA (shown in FIG. 3). The fin
height H.sub.F is between 0.144 mm and 0.248 mm (e.g., 0.23 mm) in
certain instances. The fin tip width W.sub.FT is between 0.096 mm
and 0.156 mm (e.g., 0.11 mm) in certain instances. The fin base
width W.sub.FB is between 0.18 mm and 0.24 mm (e.g., 0.21 mm) in
certain instances. The fin apex angle .THETA..sub.FA is between
19.degree. and 35.degree. (e.g., 25.degree.) in certain instances.
The fin helix angle .THETA..sub.HA is between 13.degree. and
23.degree. (e.g., 18.degree.) in certain instances. As shown in
FIG. 4, the groove(s) 160, disposed between the helical fins 110,
may be viewed to have a defined groove width W.sub.G. The groove
width W.sub.G is between 0.102 mm and 0.221 mm (e.g., 0.19 mm) in
certain instances. It will be evident to a person of ordinary skill
in the art that these dimensions are given in respect to the heat
transfer tube 100 prior to joining with the plurality of fins 210,
which may be joined using pressure expansion or mechanical
expansion (either of which may cause deformation of one or more of
the dimensions). It should be appreciated that the configuration of
the fins 110 and the grooves 160, as described above, were selected
so as to optimize the function of the heat transfer tube 100 within
a heat pump, which, as mentioned above, is capable of reversing the
flow of refrigerant so as to switch between a heating mode and a
cooling mode. As such, the heat transfer tube 100 describe herein
may not be optimized for use within a system that is only capable
of providing cooling, such as an air conditioner.
[0041] The use of the terms "a" and "and" and "the" and similar
referents, in the context of describing the invention, are to be
construed to cover both the singular and the plural, unless
otherwise indicated herein or cleared contradicted by context. The
use of any and all example, or exemplary language (e.g., "such as",
"e.g.", "for example", etc.) provided herein is intended merely to
better illuminate the invention and does not pose a limitation on
the scope of the invention unless otherwise claimed. No language in
the specification should be construed as indicating any non-claimed
elements as essential to the practice of the invention.
[0042] While the present disclosure has been described with
reference to an exemplary embodiment or embodiments, it will be
understood by those skilled in the art that various changes may be
made and equivalents may be substituted for elements thereof
without departing from the scope of the present disclosure. In
addition, many modifications may be made to adapt a particular
situation or material to the teachings of the present disclosure
without departing from the essential scope thereof. Therefore, it
is intended that the present disclosure not be limited to the
particular embodiment disclosed as the best mode contemplated for
carrying out this present disclosure, but that the present
disclosure will include all embodiments falling within the scope of
the claims.
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