U.S. patent application number 14/843210 was filed with the patent office on 2016-03-03 for evaporator and condenser section structure for thermosiphon.
This patent application is currently assigned to Aavid Thermalloy, LLC. The applicant listed for this patent is Aavid Thermalloy, LLC. Invention is credited to Maria Luisa Angrisani, Morten Soegaard Espersen, Dennis N. Jensen, Sukhvinder S. Kang.
Application Number | 20160061532 14/843210 |
Document ID | / |
Family ID | 54066265 |
Filed Date | 2016-03-03 |
United States Patent
Application |
20160061532 |
Kind Code |
A1 |
Espersen; Morten Soegaard ;
et al. |
March 3, 2016 |
EVAPORATOR AND CONDENSER SECTION STRUCTURE FOR THERMOSIPHON
Abstract
A thermosiphon device includes a closed loop evaporator section
having one or more evaporation channels that are fed by a liquid
return path, and a condenser section with one or more condensing
channels. The condenser section may include a vapor supply path
that is adjacent one or more condensing channels, e.g., located
between two sets of condensing channels. Evaporator and/or
condenser sections may be made from a single, flat bent tube, which
may be bent about an axis parallel to the plane of the flat tube to
form a turnaround and/or twisted about an axis along a length of
the tube at the tube ends. A single tube may form both evaporator
and condenser sections of a thermosiphon device, and an axially
extending wall inside the tube in the evaporator section may
separate an evaporator section from a liquid return section.
Inventors: |
Espersen; Morten Soegaard;
(Bologna, IT) ; Angrisani; Maria Luisa; (Bologna,
IT) ; Jensen; Dennis N.; (Bologna, IT) ; Kang;
Sukhvinder S.; (Concord, NH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Aavid Thermalloy, LLC |
Laconia |
NH |
US |
|
|
Assignee: |
Aavid Thermalloy, LLC
Laconia
NH
|
Family ID: |
54066265 |
Appl. No.: |
14/843210 |
Filed: |
September 2, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62044604 |
Sep 2, 2014 |
|
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|
Current U.S.
Class: |
165/104.21 |
Current CPC
Class: |
F28D 15/025 20130101;
F28D 15/0233 20130101; F28D 15/0266 20130101; F28D 15/046
20130101 |
International
Class: |
F28D 15/02 20060101
F28D015/02 |
Claims
1. A thermosiphon cooling device including: an evaporator section
including at least one evaporation channel having an inlet and an
outlet and arranged to receive heat and evaporate a liquid in the
at least one evaporation channel to deliver vapor to the
evaporation channel outlet, and a liquid return path for delivering
condensed liquid to the at least one evaporation channel, the
liquid return path having an inlet and an outlet that is fluidly
coupled to the evaporation channel inlet, wherein the evaporator
section is formed as a flat tube that is bent at a location where
the liquid return outlet communicates with the at least one
evaporation channel inlet; OR a condenser section including at
least one condenser channel having an inlet and an outlet and
arranged to transfer heat and condense a vapor in the at least one
condenser channel to deliver condensed liquid to the condenser
channel outlet, and a vapor supply path for delivering evaporated
liquid to the inlet of the at least one condenser channel, the
vapor supply path having an inlet and an outlet that is fluidly
coupled to the condenser channel inlet, wherein the condenser
section is formed as a flat tube that is bent at a location where
the vapor supply path outlet communicates with the at least one
condenser channel inlet.
2. The device of claim 1, including the evaporator section and
further comprising a manifold fluidly connected to the at least one
evaporation channel outlet and the liquid return path inlet.
3. The device of claim 2, wherein the liquid return path inlet is
positioned below the at least one evaporation channel outlet in the
manifold.
4. The device of claim 2, wherein the flat tube is bent to form a
180 degree bend where the liquid return outlet communicates with
the at least one evaporation channel inlet.
5. The device of claim 4, wherein an outlet end of the flat tube at
the evaporator channel outlet is twisted about an axis along a
length of the flat tube at the outlet end, and wherein an inlet end
of the flat tube at the liquid return path inlet is twisted about
an axis along a length of the flat tube at the inlet end.
6. The device of claim 5, wherein inlet and outlet ends of the flat
tube are twisted 90 degrees about the axes.
7. A thermosiphon cooling device including: a closed loop
evaporator section including at least one evaporation channel
having an inlet and an outlet, the evaporator section being
arranged to receive heat and evaporate a liquid in the at least one
evaporation channel to deliver vapor to the evaporation channel
outlet, and a liquid return path for delivering condensed liquid to
the at least one evaporation channel inlet, the liquid return path
having an inlet and an outlet that is fluidly coupled to the
evaporation channel inlet and being arranged such that downward
flow of condensed liquid from the liquid return path inlet to the
liquid return path outlet is separated from an upward flow of vapor
to the evaporation channel outlet, wherein the evaporator section
is formed as a flat tube that is bent at a location where the
liquid return outlet communicates with the at least one evaporation
channel inlet; and a condenser section including at least one
condensing channel arranged to receive vapor from the at least one
evaporation channel that flows upwardly in the condensing channel
and arranged to transfer heat from the vapor to a surrounding
environment to condense the vapor to a liquid which flows
downwardly in the condensing channel to the liquid return path
inlet.
8. The device of claim 7, further comprising a manifold fluidly
connecting the at least one evaporation channel and the liquid
return path with the at least one condensing channel.
9. The device of claim 7, wherein the liquid return path inlet is
positioned below the at least one evaporation channel outlet in the
manifold.
10. The device of claim 7, wherein the flat tube is bent to form a
180 degree bend where the liquid return outlet communicates with
the at least one evaporation channel inlet.
11. The device of claim 10, wherein an outlet end of the flat tube
at the evaporator channel outlet is twisted about an axis along a
length of the flat tube at the outlet end, and wherein an inlet end
of the flat tube at the liquid return path inlet is twisted about
an axis along a length of the flat tube at the inlet end.
12. The device of claim 11, wherein inlet and outlet ends of the
flat tube are twisted 90 degrees about the axes.
13. The device of claim 7, wherein the condenser section includes
first and second flat panels that sandwich a channel-defining
member so as to form a plurality of condensing channels, the first
and second flat panels defining a lower manifold that fluidly
connects lower ends of the condenser channels.
14. A thermosiphon cooling device including: a closed loop
evaporator section including at least one evaporation channel
having an inlet and an outlet and arranged to receive heat and
evaporate a liquid in the at least one evaporation channel to
deliver vapor to the evaporation channel outlet, and a liquid
return path for delivering condensed liquid to the at least one
evaporation channel, the liquid return path having an inlet and an
outlet that is fluidly coupled to the evaporation channel inlet;
and a condenser section including a vapor supply channel arranged
to receive vapor from the outlet of the at least one evaporation
channel and to deliver vapor to an upper end of the at least one
condensing channel that is arranged to transfer heat from the vapor
to a surrounding environment to condense the vapor to a liquid
which flows downwardly in the condensing channel to the liquid
return path inlet, wherein the vapor supply channel is adjacent the
at least one condensing channel.
15. The device of claim 14, further comprising a manifold fluidly
connecting the inlet of the liquid return path with a bottom of the
at least one condensing channel.
16. The device of claim 14, wherein a wall that defines at least a
part of the vapor supply channel defines at least a part of the
adjacent at least one condensing channel.
17. The device of claim 14, wherein an outlet end of the at least
one evaporator channel is inserted into the vapor supply
channel.
18. The device of claim 14, wherein an outlet end of the at least
one evaporator channel is coupled to the vapor supply channel such
that liquid flowing downwardly in the vapor supply channel does not
enter the outlet end of the at least one evaporator channel.
19. The device of claim 18, further comprising a manifold fluidly
connecting the inlet of the liquid return path with a bottom of the
at least one condensing channel, and wherein liquid flowing
downwardly in the vapor supply channel enters the manifold.
20. The device of claim 14, wherein the condenser section includes
a plurality of parallel condensing channels, and wherein the vapor
supply channel is located between two sets of the condensing
channels.
21. The device of claim 14, wherein the condenser section includes
first and second flat panels that sandwich a channel-defining
member so as to form a plurality of condensing channels and the
vapor supply channel, the first and second flat panels defining a
lower manifold that fluidly connects lower ends of the condenser
channels, and defining an upper manifold that fluidly connects
upper ends of the condensing channels and the vapor supply
channel.
22. The device of claim 14, wherein the evaporator section is
formed as a flat tube that is bent at a location where the liquid
return outlet communicates with the at least one evaporation
channel inlet.
23. The device of claim 12, wherein the flat tube is bent to form a
180 degree bend where the liquid return outlet communicates with
the at least one evaporation channel inlet.
24. The device of claim 23, wherein an outlet end of the flat tube
at the evaporator channel outlet is twisted about an axis along a
length of the flat tube at the outlet end, and wherein an inlet end
of the flat tube at the liquid return path inlet is twisted about
an axis along a length of the flat tube at the inlet end.
25. The device of claim 24, wherein inlet and outlet ends of the
flat tube are twisted 90 degrees about the axes.
26. The device of claim 25, wherein the condenser section includes
a plurality of condensing channels, and wherein the outlet end of
the flat tube is fluidly coupled to the vapor supply channel, and
the inlet end of the flat tube is fluidly coupled to a manifold
that fluidly couples lower ends of the plurality of condensing
channels.
27. A thermosiphon cooling device including: a condenser section
including a plurality of condensing channels arranged to receive
evaporated liquid and arranged to transfer heat from the evaporated
liquid to a surrounding environment to condense the evaporated
liquid to a liquid which flows downwardly in the condensing
channels, wherein the condenser section includes first and second
panels that sandwich a channel-defining member so as to form the
plurality of condenser channels, the first and second panels
defining a lower manifold that fluidly connects lower ends of the
condenser channels.
28. The device of claim 27, wherein the first and second panels
define an upper manifold that fluidly connects upper ends of the
condenser channels.
29. The device of claim 27, wherein the channel-defining member
additionally defines a vapor supply channel.
30. The device of claim 29, wherein the vapor supply channel is
located between sets of condensing channels.
31. A thermosiphon cooling device including: an evaporator section
including a tube with an axially extending separation wall within
the tube to separate at least one evaporation channel having an
inlet and an outlet from a liquid return path for delivering
condensed liquid to the at least one evaporation channel, the
axially extending wall having a bottom end that is positioned away
from a lower end of the tube and defining the inlet for the at
least one evaporation channel.
32. The device of claim 31, wherein the tube defines a condenser
section.
33. The device of claim 31, wherein an inner surface of the tube
has fins or channels at the at least one evaporation channel.
34. The device of claim 33, wherein the inner surface includes fins
or channels at the liquid return path, and the fins or channels at
the at least one evaporation channel are different from the fins or
channels at the liquid return path.
35. The device of claim 31, wherein the tube has upper and lower
sections, the evaporator section being located at the lower section
of the tube, the device further comprising a condenser section at
the upper section of the tube.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/044,604, filed Sep. 2, 2014, which is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1) Field of Invention
[0003] This invention relates generally to thermosiphon devices and
other heat transfer devices that employ a two-phase fluid for
cooling. [0004] 2) Description of Related Art
[0005] Thermosiphon devices are widely used for cooling systems,
such as integrated circuits and other computer circuitry. For
example, U.S. Patent Publication 2013/0104592 discloses a
thermosiphon cooler used to cool electronic components located in a
cabinet or other enclosure.
SUMMARY OF THE INVENTION
[0006] In accordance with an aspect of the invention, a
thermosiphon device may have a closed loop evaporator section
combined with a counterflow type condenser section. Generally,
thermosiphon devices are made such that both the evaporator and
condenser sections operate in a counterflow-type mode, or with a
closed loop flow. Counterflow type devices tend to be less
efficient than closed loop systems, but are suitable for certain
applications and tend to be lower cost systems. On the other hand,
closed loop systems can have a larger overall size, e.g., because
of the dedicated flow paths and other components. By combining a
closed loop evaporator section with a counterflow condenser
section, the inventors have found that improved thermal performance
in comparison to standard counterflow devices can be provided, but
with lower equipment cost and overall size of the system.
[0007] For example, a thermosiphon cooling device may include a
closed loop evaporator section having at least one evaporation
channel with an inlet and an outlet. The evaporator section may be
arranged to receive heat and evaporate a liquid in the at least one
evaporation channel to deliver vapor to the evaporation channel
outlet. A liquid return path, having an inlet and an outlet, may
deliver condensed liquid to the at least one evaporation channel
inlet, and the liquid return path may be arranged such that
downward flow of condensed liquid from the liquid return path inlet
to the liquid return path outlet is separate from an upward flow of
vapor to the evaporation channel outlet. Thus, the evaporator
section may operate with a closed loop flow. A condenser section of
the device may include at least one condensing channel arranged to
receive vapor from the at least one evaporation channel that flows
upwardly in the condensing channel and arranged to transfer heat
from the vapor to a surrounding environment to condense the vapor
to a liquid which flows downwardly in the condensing channel to the
liquid return path inlet. That is, the condenser section may
operate in a counterflow arrangement in which vapor and condensed
liquid flow in the same channel(s).
[0008] In some embodiments, a manifold may fluidly connect the at
least one evaporation channel and the liquid return path with the
at least one condensing channel. Thus, the manifold may function as
a vapor/liquid separator such that vapor entering the manifold is
separated from any liquid in the manifold and flows into condensing
channels. On the other hand, liquid in the manifold may flow to the
liquid return path. In some cases, the liquid return path inlet is
positioned below the at least one evaporation channel outlet in the
manifold so liquid preferentially flows into the liquid return
path.
[0009] In one embodiment, the evaporator section is formed as a
flat tube that is bent at a location where the liquid return outlet
communicates with the at least one evaporation channel inlet. For
example, the flat tube may be bent to form a 180 or other degree
bend where the liquid return outlet communicates with the at least
one evaporation channel inlet. In addition, or alternately, an
outlet end of the flat tube at the evaporator channel outlet may be
twisted about an axis along a length of the flat tube at the outlet
end, and/or an inlet end of the flat tube at the liquid return path
inlet may be twisted about an axis along a length of the flat tube
at the inlet end. For example, inlet and/or outlet ends of the flat
tube may be twisted 90 degrees about the axes. This type of
arrangement may allow for simplified connections between the
evaporator section and other parts of the thermosiphon device,
e.g., the need for connectors to provide bends in the system flow
path may be eliminated and replaced by bent/twisted tube
sections.
[0010] In another aspect of the invention, a thermosiphon device
may include a closed loop condenser section that has a liquid
bypass or exit path for condensed liquid in the vapor supply path
of the condenser section. This arrangement may reduce the concern
regarding condensate forming in the vapor supply path, e.g.,
allowing the vapor supply path to be positioned closely to
condensing channels of the device in such a way that condensate may
form in the vapor supply path. For example, a thermosiphon cooling
device includes a closed loop evaporator section having at least
one evaporation channel with an inlet and an outlet and arranged to
receive heat and evaporate a liquid in the at least one evaporation
channel to deliver vapor to the evaporation channel outlet. A
liquid return path, having an inlet and outlet, may deliver
condensed liquid to the at least one evaporation channel. A
condenser section may have a vapor supply channel arranged to
receive vapor from the outlet of the at least one evaporation
channel and deliver vapor to an upper end of the at least one
condensing channel. The at least one condensing channel may be
arranged to transfer heat from the vapor to a surrounding
environment to condense the vapor to a liquid which flows
downwardly in the condensing channel to the liquid return path
inlet. The vapor supply channel may carry vapor flow, which is
separate from condensed liquid flow in the condensing channels, yet
the vapor supply channel may be immediately adjacent the at least
one condensing channel. This is in contrast to systems which have a
similar closed loop condenser arrangement, but have the vapor
supply path physically separated from condensing channels. This
separation is typically provided so that vapor in the vapor supply
does not prematurely condense, which is known to disrupt the
cyclical flow in a thermosiphon. However, the inventors have
discovered that a vapor supply path can be provided immediately
adjacent one or more condensing channels, and yet may be configured
so that gravity-driven cyclical flow is not disrupted. In some
embodiments, for example, an area where the vapor supply channel is
fluidly connected to the outlet of the evaporator section may be
provided with a liquid bypass or other flow path so that condensate
in the vapor supply channel may drain to a manifold or other liquid
return path of the device.
[0011] For example, an outlet end of the at least one evaporator
channel may be inserted into or otherwise coupled to the vapor
supply channel, and the coupling may be arranged so that liquid
flowing downwardly in the vapor supply channel does not enter the
outlet end of the at least one evaporator channel. Instead, the
coupling between the outlet end and the vapor supply channel may
have one or more gaps or other flow paths so that liquid in the
vapor supply channel can bypass the outlet end and flow to a liquid
return path of the device. In some embodiments, a manifold may
fluidly connect the inlet of the liquid return path with a bottom
of the at least one condensing channel, and any liquid that exits
from the vapor supply channel may enter the manifold. As a result,
the vapor supply channel may be surrounded by condensing channels
without disrupting flow in the thermosiphon device because liquid
in the vapor path can be removed. For example, the condenser
section may have a plurality of parallel condensing channels, and
the vapor supply channel may be located between two sets of the
condensing channels, e.g., along a centerline of the condenser
section.
[0012] In another aspect of the invention, a thermosiphon cooling
device includes an evaporator section with at least one evaporation
channel having an inlet and an outlet and arranged to receive heat
and evaporate a liquid in the at least one evaporation channel to
deliver vapor to the evaporation channel outlet. A liquid return
path, having an inlet and outlet, may deliver condensed liquid to
the at least one evaporation channel, e.g., by having the outlet
fluidly coupled to the evaporation channel inlet. The evaporator
section may be formed as a flat tube that is bent, e.g., at 180
degrees or more or less, at a location where the liquid return
outlet communicates with the at least one evaporation channel
inlet. Such an arrangement may make for a much simplified
evaporator section, e.g., by eliminating one or more connections
between parts of an evaporator section required by other
arrangements. The bent, flat tube configuration for an evaporator
section is also applicable to a condenser section. For example, a
condenser section may have at least one condenser channel with an
inlet and an outlet and arranged to transfer heat and condense a
vapor in the at least one condenser channel to deliver condensed
liquid to the condenser channel outlet. A vapor supply path, having
an inlet and an outlet, may deliver evaporated liquid to the inlet
of the at least one condenser channel, e.g., by having the outlet
fluidly coupled to the condenser channel inlet. The condenser
section may be formed as a flat tube that is bent, e.g., at 180
degrees or more or less, at a location where the vapor supply path
outlet communicates with the at least one condenser channel
inlet.
[0013] In some embodiments, a manifold may be fluidly connected to
the at least one evaporation channel outlet and the liquid return
path inlet, and the liquid return path inlet may be positioned
below the at least one evaporation channel outlet in the manifold.
This construction may make for a simplified device, since a single
manifold may be used to make vapor and liquid connections between
the evaporator section and the condenser section, as well as
function as a vapor/liquid separator.
[0014] In some embodiments, an outlet end of the flat tube at the
evaporator channel outlet may be twisted about an axis along a
length of the flat tube at the outlet end, and/or an inlet end of
the flat tube at the liquid return path inlet may be twisted about
an axis along a length of the flat tube at the inlet end. For
example, the inlet and outlet ends of the flat tube may be twisted
90 degrees about the axes. This arrangement may allow for
relatively compact connections between the evaporator section and
other portions of the thermosiphon device without the use of
additional connectors. Instead, the tube ends may be twisted as
needed to provide a suitably compact and correctly oriented
connection.
[0015] In another aspect of the invention, a thermosiphon cooling
includes a condenser section having a plurality of condensing
channels arranged to receive evaporated liquid and arranged to
transfer heat from the evaporated liquid to a surrounding
environment to condense the evaporated liquid to a liquid which
flows downwardly in the condensing channels. The condenser section
may include first and second panels that sandwich a
channel-defining member so as to form the plurality of condenser
channels, with the first and second panels defining a lower
manifold that fluidly connects lower ends of the condenser
channels. Such an arrangement may provide a simple and efficient
design which eliminates a variety of parts, such as an end cap for
the upper ends of the condenser channels. In some embodiments, the
first and second panels define an upper manifold that fluidly
connects upper ends of the condenser channels, e.g., so the
condenser section can be used as a closed loop type device.
Alternately, or in addition, the channel-defining member may define
a vapor supply channel, e.g., that is located between sets of
condensing channels.
[0016] In another illustrative embodiment, a thermosiphon cooling
device includes an evaporator section with a tube and an axially
extending separation wall within the tube to separate at least one
evaporation channel from a liquid return path in the tube. The
axially extending separation wall may have a bottom end that is
positioned away from a lower end of the tube and define the inlet
for the at least one evaporation channel. This configuration may
provide for a simplified evaporator device that includes a single
tube and a plate or other element positioned inside the tube to
function as a separation wall. In some embodiments, the tube may
also define a condenser section, e.g., an inner surface of the tube
may have fins or channels that define one or more condensing
channels, one or more evaporation channels, and one or more liquid
return paths. In some cases, the fins or channels at the at least
one evaporation channel are different from the fins or channels at
the liquid return path. For example, the channels or grooves at the
evaporation channels may be arranged to enhance liquid boiling,
whereas the channels or grooves at the liquid return path may be
arranged to enhance condensate consolidation and flow.
[0017] Although not described above, conductive thermal transfer
structure, such as a plurality of fins, may be in direct,
conductive thermal contact with portions of an evaporator section,
e.g., adjacent one or more evaporation channels, in contact with
portions of a condenser section, e.g., adjacent one or more
condensing channels, and/or associated with other parts of the
thermosiphon device to influence heat transfer and/or cooling fluid
flow.
[0018] These and other aspects of the invention will be apparent
from the following description. Also, it should be appreciated that
different aspects of the invention may be combined in a variety of
different ways. For example, aspects related to closed loop
evaporator flow and counterflow condenser flow may be combined with
the use of a flat, bent tube evaporator, and/or with a condenser
formed by sandwiching a channel-defining member between opposed
panels.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The accompanying drawings, which are incorporated in and
form a part of the specification, illustrate select embodiments of
the present invention and, together with the description, serve to
explain the principles of the inventions. In the drawings:
[0020] FIG. 1 is a perspective view of a thermosiphon device in an
illustrative embodiment that incorporates aspects of the
invention;
[0021] FIG. 2 shows a cross sectional side view of the FIG. 1
device;
[0022] FIG. 3 shows a cross sectional close up view of a modified
version of the FIG. 2 embodiment;
[0023] FIG. 4 shows a cross sectional close up view of a modified
version of the FIG. 3 embodiment;
[0024] FIG. 5 shows a cross sectional close up view of a condenser
section having a channel-defining member;
[0025] FIG. 6 shows a partial section view of headers joining
condenser and evaporator sections in an illustrative
embodiment;
[0026] FIG. 7 shows a perspective view of thermosiphon devices
having a manifold that fluidly couples evaporator sections at a
turnaround end of the sections;
[0027] FIG. 8 shows a perspective view of a thermosiphon device
having inlet and outlet ends of evaporator sections coupled to a
connecting tube of a manifold;
[0028] FIG. 9 shows a close up view of a manifold arrangement in
the FIG. 8 embodiment;
[0029] FIG. 10 shows an evaporator section of a thermosiphon device
that includes thermal transfer structure having fins extending
between evaporator sections;
[0030] FIG. 11 shows a perspective view of a thermosiphon device in
which a tube defines condenser and evaporator sections;
[0031] FIG. 12 shows a cross sectional perspective view of an
evaporator section of the tube in the FIG. 11 embodiment;
[0032] FIG. 13 shows a cross sectional view along the line 13-13 in
FIG. 12; and
[0033] FIG. 14 shows side view of a thermosiphon device in another
illustrative embodiment.
DETAILED DESCRIPTION
[0034] Aspects of the invention are not limited in application to
the details of construction and the arrangement of components set
forth in the following description or illustrated in the drawings.
Other embodiments may be employed and aspects of the invention may
be practiced or be carried out in various ways. Also, aspects of
the invention may be used alone or in any suitable combination with
each other. Thus, the phraseology and terminology used herein is
for the purpose of description and should not be regarded as
limiting.
[0035] In accordance with an aspect of the invention, a
thermosiphon cooling device includes an evaporator section formed
as a flat tube that is bent at a location where the liquid return
outlet communicates with the at least one evaporation channel
inlet. For example, the evaporator section may include at least one
evaporation channel having an inlet and a liquid return path having
an outlet that is fluidly coupled to the evaporation channel inlet,
where the at least one evaporation channel and the liquid return
path are formed as a flat tube that is bent at a location where the
liquid return outlet communicates with the at least one evaporation
channel inlet. For example, the flat tube may be arranged as a
multi-port extruded (MPE) structure that is generally flat and has
a plurality of parallel channels extending along the tube length,
at least in the evaporator channel section. The MPE tube may be
bent, e.g., to form a 180 degree bend, that defines an area where
the liquid return path joins to the evaporation channel(s). Such an
arrangement may make for a simplified, low-weight construction that
can be made at relatively low cost.
[0036] For example, FIG. 1 shows an illustrative embodiment of a
thermosiphon device 10, e.g., used to cool electronics devices in a
closed cabinet or other enclosure, or in an open environment. That
is, as is understood by those of skill in the art, a heat-receiving
area 5 of one or more evaporator sections 2 of the device 10 may be
thermally coupled with electronics or other heat-generating devices
to be cooled, e.g., by direct contact, heat pipe(s), heat
exchanger, etc. Vapor generated in one or more evaporation channels
in the heat-receiving area 5 may flow to one or more condenser
sections 1 that dissipate heat received from the evaporator
section(s) 2, e.g., to air or other fluid in an environment around
the device 10. In some embodiments, the evaporator section(s) 2 may
be positioned inside of a sealed enclosure while the condenser
section(s) 1 are located in an environment outside of the
enclosure. By providing the evaporator section(s) 2 inside a sealed
enclosure and the condenser section(s) 1 outside of the enclosure,
devices in the enclosure may be cooled while being contained in an
environment protected from external conditions, e.g., protected
from dirt, dust, contaminants, moisture, etc. Of course, use of a
thermosiphon device with a sealed enclosure is not required, e.g.,
the device may be used in a completely open system in which heat
generating devices to be cooled are thermally coupled to one or
more evaporator section(s) 2 of the device 10.
[0037] In simplified form, the thermosiphon device 10 operates to
cool heat generating devices by receiving heat at the
heat-receiving area 5 of the evaporator section(s) 2 such that
liquid in evaporation channels 22 boils or otherwise vaporizes.
Heat may be received at the evaporation channels 22 by warm air
(heated by the heat generating devices) flowing across a thermal
transfer structure (e.g., heat sink fins) that is thermally coupled
to the evaporation channels 22 or in other ways, such as by a
direct conductive path, one or more heat pipes, a liquid heat
exchanger, etc. Vapor flows upwardly from the evaporation channels
22 and into a vapor supply path 11 of a condenser section 1. The
vapor continues to flow upwardly in the vapor supply path 11 until
reaching a turnaround 14 of the condenser section 1. At this point,
the vapor flows downwardly into one or more condensing channels 12
of the condenser section 1, where the vapor condenses to a liquid
and flows downwardly into the manifold 3. Heat removed from the
vapor during condensation may be transferred to thermal transfer
structure coupled to the condensing channels 12, e.g., one or more
fins conductively coupled to the condenser section 1 adjacent the
condensing channels 12. In turn, heat may be removed from the
thermal transfer structure by cool air flowing across the
structure, by a liquid bath, a liquid heat exchanger, refrigerant
coils, or other arrangement. The condensed liquid flows downwardly
from the condensing channels 12 into a liquid return path 21 of an
evaporator section 2 until reaching a turnaround 24 of the
evaporator section 2. The liquid then enters an evaporator
channel(s) 22 and the process is repeated.
[0038] In the FIG. 1 embodiment, the evaporator section(s) 2 are
each formed from a single flat tube, which may be arranged as an
MPE tube or other suitable structure. The tube is bent to form the
turnaround 24, i.e., where an outlet of the liquid return path 21
is coupled to the inlet of the evaporation channel(s) 22. Any
suitable bend may be provided, and in this example, a 180 degree
bend is made about an axis that is parallel to the plane of the
tube and is perpendicular or otherwise transverse to the length of
the tube. Other bend arrangements are possible, though, including a
bend about an axis that is perpendicular to the plane of the tube.
The heat-receiving area 5 of the evaporator section(s) 2 may be out
of contact with the liquid return path 21 portion, e.g., so little
or no heat transfer occurs between the two.
[0039] In accordance with another aspect of the invention, an inlet
end and/or an outlet end of the tube forming the evaporator
section(s) 2 may be twisted, e.g., about an axis that is along the
length of the tube. In this embodiment, the inlet and outlet ends
of the tube are twisted about an axis that extends along an
approximate center of the tube along the length of the tube.
However, twisting about other axes extending along a length of the
tube or otherwise arranged are possible.
[0040] While in this embodiment only the evaporator section(s) 2
are formed from a bent, flat tube, one or more condenser sections 1
may be formed from a bent tube in addition or alternately to the
evaporator section(s) 2. In such a case, the condenser section may
have at least one condenser channel formed as a part of the tube
with each condenser channel having an inlet and an outlet and
arranged to transfer heat and condense a vapor in the at least one
condenser channel to deliver condensed liquid to the condenser
channel outlet. Another part of the tube may form a vapor supply
path for delivering evaporated liquid to the inlet of the at least
one condenser channel. The vapor supply path may have an inlet and
an outlet that is fluidly coupled to the condenser channel inlet,
and the flat tube may be bent at a location where the vapor supply
path outlet communicates with the at least one condenser channel
inlet. Moreover, ends of the tube may be twisted, e.g., in a way
similar to the evaporator sections 2 shown in FIG. 1.
[0041] FIG. 2 shows a cross sectional side view of the FIG. 1
device, and illustrates how an outlet end 26 of the evaporator
section 2 is coupled to the inlet of the vapor supply path 11 of
the condenser section 1. As described above and in accordance with
an aspect of the invention, this coupling may in some cases not be
liquid-tight so that any condensate in the vapor supply path 11 can
flow through a gap or other flow path between the outlet end 26 of
the evaporator section 2 and the vapor supply path 11 and into the
manifold 3. For example, in this embodiment, the vapor supply path
11 is positioned adjacent condensing channels 12, which may
increase the likelihood that vapor in the supply path 11 condenses
to form a liquid. Such condensed liquid may flow downwardly in the
vapor supply path 11, but may not enter the outlet end 26 of the
evaporator section 2 because the liquid may exit the vapor supply
path 11 via a bypass or other flow path to the manifold 3.
[0042] That is, the manifold 3 in this embodiment provides a liquid
flow path for condensed liquid to return to the evaporator section
2. The inlet end 27 of the evaporator section 2 (i.e., at the inlet
to the liquid return path 21) is joined to the manifold 3, which
fluidly couples the lower ends of the condenser channels 12 to the
inlet end 27. Thus, vapor may flow upwardly in the vapor supply
path 11 and into the upper ends of the condenser channels 12.
Condensed liquid may flow downwardly into the manifold 3 and be
routed to the inlet end 27 of the evaporator section 2. Since the
inlet end 27 is positioned below the outlet end 26 of the
evaporator section 2, liquid in the manifold 3 will flow first into
the inlet end 27. In this embodiment, the manifold 3 includes a
tube 35 that is coupled to each of the separate condenser sections
1, e.g., to allow for easier filling of the device 10 with cooling
liquid and/or pressure equalization across different portions of
the device.
[0043] FIG. 3 shows a cross sectional close up view of a modified
version of the FIGS. 1 and 2 embodiment in which a connecting tube
35 is not provided. Other than this change, however, this
embodiment is identical to that in FIGS. 1 and 2. In this
embodiment, the manifold 3 is formed from a pair of clam shell
pieces or sections 3a, 3b that may be stamped, molded or otherwise
formed to receive the condenser section 1 at an upper opening and
to receive the inlet and outlet ends 27, 26 of the evaporator
section 2 at respective lower openings. A single brazing or other
suitable operation may join the manifold sections 3a, 3b, the
condenser section 1 and the ends 26, 27 of the evaporator section
2. Of course, other construction arrangements are possible, but
this arrangement provides for a simple, relatively lightweight and
inexpensive device.
[0044] Thermal transfer structure 9, such as one or more fins 9,
may be thermally coupled to the condenser section(s) 1, e.g., in
areas adjacent the condenser channels 12. This may assist in heat
transfer from vapor in the condenser channels 12 and/or affect how
cooling fluid flows across the thermal transfer structure 9. Of
course, any suitable thermal transfer structure may be employed,
including heat sink structures, heat pipes, heat exchangers, cold
plates, etc.
[0045] In accordance with another aspect of the invention, a
thermosiphon device may include a closed loop evaporator section,
i.e., a liquid return path that leads to the inlet of one or more
evaporation channels which have an outlet separate from the liquid
return path, and a counterflow-type condenser section. That is, the
condenser section may have at least one condensing channel arranged
to receive vapor from at least one evaporation channel that flows
upwardly in the condensing channel and arranged to transfer heat
from the vapor to a surrounding environment to condense the vapor
to a liquid which flows downwardly in the condensing channel to the
liquid return path inlet. Thus, vapor to be condensed flows
upwardly in the condensing channels while condensed liquid flows
downwardly in the condensing channels. This is in contrast to a
system like that in FIG. 2 where vapor flows upwardly in a
dedicated vapor supply path 11 and enters inlets to condensing
channels 12 at a upper end of the channels. Instead, vapor may
enter the condensing channels 12 at a lower end of the channels,
and condensed liquid may likewise exit from the lower end of the
channels. One benefit to such an arrangement is that a turnaround
14 need not be provided for the condenser sections 1, reducing
materials and cost. Instead, condenser channels 12 may "dead end"
at an upper end of the channels so the channels are not in fluid
communication at the upper end. Also, a vapor supply path 11 need
not be provided, allowing for an increased density of condenser
channels 12.
[0046] FIG. 4 shows a cross sectional close up view similar to that
of FIG. 3, except that the FIG. 1 embodiment has been modified to
eliminate the vapor supply path 11. As a result, the inlet and
outlet ends 27, 26 of the evaporator section 2 extend into the
manifold 3 such that both the outlet of the evaporator channels 22
and the inlet of the liquid return path 21 are in fluid
communication with the manifold 3 and the lower ends of the
condenser channels 12. The inlet end 27 is positioned below the
outlet end 26 so that liquid preferentially flows into the inlet
end 27. FIG. 4 also shows how a connector tube 35 may be joined to
the manifold 3, e.g., a slot or opening 35a of the tube 35 may be
aligned with a corresponding opening at a bottom of the manifold 3
so that the tube 35 and the manifold 3 are in fluid
communication.
[0047] In another aspect of the invention, a thermosiphon device
includes a condenser section with first and second side panels that
sandwich a channel-defining member so as to form a plurality of
condenser channels and/or a vapor supply path. In some embodiments,
the first and second side panels may define a lower manifold that
fluidly connects lower ends of the condenser channels, and/or
define an upper manifold that fluidly connects upper ends of the
condenser channels. Such a structure may provide for a condenser
section that is simple in construction, lightweight, and efficient.
The channel-defining member may be arranged in a variety of ways,
such as a stamped plate with walls to define the condensing
channels when positioned between the side panels.
[0048] For example, FIG. 5 shows a cross sectional view of a
condenser section 1 that has one of the side panels 16 removed such
that a channel-defining member 17 can be seen along with a side
panel 15. In this embodiment, the channel-defining member 17 is
formed as a punched, stamped or otherwise formed element with a
plurality of wall portions to define, at least partially, a
plurality of condensing channels 12 and a vapor supply path 12. Of
course, other arrangements for the channel-defining member 17 is
possible, e.g., the channel-defining member 17 may be formed as a
set of individual ribs that are assembled between the side panels
15, 16, may be formed as a corrugated or extruded sheet, etc. Also,
the channel-defining member 17 need not necessarily define
continuous channels, but rather could have a pattern of dints,
cutouts or pin fins, etc. that define discontinuous channels. In
this embodiment, the channel-defining member 17 is arranged to be
brazed or soldered to the inside surface of the side panels 15, 16,
but it should be understood that other arrangements are possible,
such as forming the channel-defining member 17 as part of one or
both of the panels 15, 16. One advantage to the illustrated
embodiment is that the condenser section 1 can be formed by simply
positioning the channel-defining member 17 on a surface of a metal
sheet, and then folding the metal sheet so that the
channel-defining member 17 is positioned between opposed parts of
the sheet, i.e., side panels 15, 16 of the condenser section 1.
This can make for a very inexpensively made and efficient condenser
section 1. Also, if the condenser section 1 is to operate as a
counterflow type device, an upper header or void at the turnaround
end need not be provided. That is, a vapor supply path 11 need not
be provided and each of the condensing channels 12 may "dead end"
at an upper end of the channels so that the upper ends of the
channels 12 are not fluidly coupled together. This arrangement may
also allow for the elimination of a terminating cap at the
turnaround end of the condenser section 1, e.g., because the panels
15, 16 may be joined together to close the condenser section 1.
[0049] In this embodiment, thermal transfer structure 9 in the form
of U-shaped fins 9 are attached to one or both of the panels 15,
16, e.g., to assist in transferring heat from vapor in the
condensing channels 12. In this embodiment, the fins 9 are mounted
parallel to the direction in which the condensing channels 12
extend, but could be positioned in other ways, such as at different
angles. That is, this illustrative embodiment is configured to
operate using natural convective flow such that air or other fluid
in or around the fins 9 is heated and flows upwardly due to
gravity. However, the fins 9 may be arranged for forced convection
applications, e.g., where the fins 9 rotated 90 degrees so the fins
9 extend in a direction perpendicular to the direction along which
the condensing channels 12 extend. Configuring the condenser
section 1 to operate in as a forced convection device may enable
the condenser section 1 to be reduced in size, assuming a power
input is unchanged. It should also be noted that the thermal
transfer structure 9 may take a variety of different shapes or
configurations than that shown, e.g., the fins 9 may be louvered,
corrugated, include pin elements, etc.
[0050] In accordance with another aspect of the invention, a header
used to join a condenser section 1 and an evaporator section 2 may
be arranged to include a connecting tube or other conduit so that
adjacent headers can fluidly communicate with each other. That is,
while the embodiments in FIGS. 1 and 4 have a separate tube 35 that
is attached to headers 3, tube or other conduit sections may be
formed as part of each header and joined together to form a
connecting tube 35. For example, FIG. 6 shows an embodiment in
which headers 3 include a connecting tube 35 formed as part of the
header 3 structure. The connecting tubes 35 of adjacent headers 3
are joined together, e.g., by brazing, solder, welding, adhesive,
etc. so that the headers 3 fluidly communicate via passageways 35b.
The tubes 35 may be formed in any suitable way, such as by drawing,
drilling, casting, molding, etc. This view in FIG. 6 also shows how
the headers 3 are formed from two clam-shell type parts or opposed
sections 3a, 3b that are joined together to form the header 3. The
sections 3a, 3b may be formed by stamping, molding, etc. and may
allow for simplified assembly of the header 3 with the condenser
and evaporator sections 1, 2. For example, the manifold end of the
condenser section 1, and the inlet and outlet ends 27, 26 of the
evaporator section 2 may be assembled with the header sections 3a,
3b, and all of the assembled parts attached together in a single
operation, such as brazing. This can not only provide simplified
assembly, but also allow for easier filling of the thermosiphon
devices 10 in a single operation since the devices 10 are all in
fluid communication with each other.
[0051] In some embodiments, thermosiphon devices ganged together to
cool one or more heat generating devices may be fluidly coupled in
ways or locations other than that shown in FIGS. 1 and 6. For
example, FIG. 7 shows an illustrative embodiment where the
turnarounds of the evaporator sections 2 are fluidly coupled by a
manifold 29. In this case, the outlet end of the liquid return path
21 is coupled to the manifold 29, as is the inlet end of the
evaporator channels 22. The manifold 29 may be provided in one or
more separate sections, e.g., if the device 10 is operated at
inclined angles, the manifold 29 may be divided into any number of
sub-sections to avoid a situation where a part of the manifold 29
is drained of liquid. A similar approach may also be used for a
central manifold 3 in case the device is to be operated at inclined
angles.
[0052] Of course, other manifold arrangements are possible, such as
that shown in FIG. 8 in which inlet and outlet ends 26, 27 of
evaporator sections 2 are coupled to a connecting tube 35 of the
manifolds 3. FIG. 9 shows a close up view, and illustrates that the
inlet end 27 of the liquid return path 21 is positioned below the
outlet end 26 of the evaporator channels 22 so that condensed
liquid preferentially flows into the inlet end 27. The vapor speed
in the vertical direction in the connector tube 35 and headers 3 is
low due to the high area of the free liquid-vapor interface, which
enhances liquid-vapor separation. Though the ends 26, 27 of the
evaporator sections 2 are not twisted as in earlier embodiments,
the ends could be twisted to engage with the connector tube 35
and/or header 3. FIG. 9 also illustrates how the manifolds 3 can be
formed from pairs of opposed sections 3a, 3b which define an
opening to receive a lower end of the condenser section 1 and an
opening to communicate with the connector tube 35.
[0053] Although the embodiments above only describe the use of
thermal transfer structure 9, such as a finned heat sink, with
condenser sections 1, thermal transfer structure may be used with
evaporator sections 2. For example, FIG. 10 shows an embodiment in
which a finned heat sink 9 has fins 91 extending between adjacent
evaporator sections 2. The fins 91 and other portions of the
thermal transfer structure 9 are out of contact with the liquid
return path 21 portion of the evaporator section 2 so as to
minimize heat transfer to the liquid return path 21. However, the
heat sink 9 is directly coupled to the heat receiving area
5/evaporation channels 22 portion of the evaporator sections 2 and
to one or more heat-generating devices, such as electronic
circuitry. The fins 91 may help dissipate heat, particularly where
the thermosiphon device 10 is used in an open environment, and
having the fins 91 extend between the evaporator sections 2 (and
away from the heat generating devices) may help reduce the overall
size of the device 10 while enhancing its cooling capability. While
in this illustrated embodiment, the thermal transfer structure 9 is
arranged as an extruded (or otherwise formed) heat sink structure
with a base plate secured to the heat receiving area 5 and fins 91
extending from the base plate between the evaporator sections 2,
the thermal transfer structure 9 may be arranged in other ways. For
example, the thermal transfer structure 9 could be made part of a
cabinet or other housing for the heat generating devices, e.g., the
thermal transfer structure 9 could include a cool plate attached to
a cabinet in which heat generating devices are located. In another
arrangement, heat generating devices may be attached directly to
the thermal transfer structure 9 that is integrated with a cabinet
or housing. Thus, the thermal transfer structure 9 may provide a
mounting support for one or more thermosiphon devices 10 and/or one
or more heat-generating devices inside of a cabinet or housing.
That is, thermal transfer structure 9 may be secured in a cabinet
or housing (or other configuration), and one or more thermosiphon
devices 10 may be mounted to the thermal transfer structure 9. One
or more heat generating devices may also be mounted to the thermal
transfer structure 9, or may be supported by a cabinet or other
structure.
[0054] In another aspect of the invention, a single tube may
incorporate both an evaporator section and a condenser section. The
evaporator section of the tube may include different internal
protuberance and/or groove arrangements arranged to enhance
condensation routing or liquid evaporation. Also, a part of the
evaporation section may include a separation wall that extends
axially in the tube and separates an evaporation portion from a
liquid return path in the tube. The separation wall may have a low
thermal conductivity and may made with grooves in the tube interior
to retain the wall in place. For example, FIG. 11 shows a
perspective view of a thermosiphon device 10 with one of the tubes
25 defining a condenser and evaporation section 1, 2 shown in cross
section. Ends of the tubes 25 may be closed by caps 14, 24, or
otherwise closed. The condenser section 1 includes multiple grooves
formed in the inner wall of the tube 25 that function as condensing
channels 12. Vapor produced in the evaporation section 2 may flow
upwardly in the grooves of the tube inner wall and/or at a central
portion of the tube 25. Thermal transfer structure 9, such as one
or more fins, may be coupled to the condenser section 1 to assist
in heat transfer from the vapor in the condenser sections 1 and/or
to attach the tubes 25 together.
[0055] The evaporator section 2 also includes grooves in the inner
wall of the tube 25, e.g., to provide condensate liquid flow paths
and evaporation channels. A separation wall 23 may be positioned in
the tube 25 and extend axially along the tube 25 to separate
evaporation channels 22 from a liquid return path 21 of the
evaporator section 2. FIG. 12 shows a close up view of the
evaporator section 2 and illustrates how the separation wall 23
extends along a portion of the tube 25. As can be seen in FIG. 13,
the separation wall 23 may engage with grooves 19 that hold the
separation wall 23 in place and may provide a liquid-tight seal
between the wall 23 and the inner wall of the tube 25. In this
embodiment, the separation wall 23 may be slid into the grooves 19
from the end of the tube 25, although other arrangements are
possible. In any case, the separation wall 23 may extend across an
internal space of the tube 25 so as to form a chord or chord-like
element. Grooves and/or fins that define the evaporation channels
22 may be arranged differently than grooves that define liquid
return paths 21. For example, the grooves and/or fins at the
evaporation channels 22 may include sharp corners to promote
boiling, whereas grooves/fins at the liquid return paths 21 may
include convex-shaped flutes at a radially inner end that enable
very thin condensation films and use surface tension to urge the
condensed fluid to flow into the grooves. The separation wall 23
may have a low thermal conductivity so that thermal transfer
between the area around the evaporation channels 22 to the liquid
return path 21 is minimized. One or more heat generating devices
may be thermally coupled to the tube 25 in an area where the
evaporation channels 22 are located, e.g., on the left side in FIG.
13. While in this embodiment, the tubes 25 are formed from a single
continuous piece, two or more different tube sections may be joined
together, e.g., where a condenser section 1 is made of aluminum and
an evaporator section 2 is made of copper. Other variations are
possible as well, such as a portion of the tube 25 where the
evaporation channels 22 are provided may be made of a highly
thermally conductive material, such as copper, while another
portion of the tube 25 where the liquid return path 21 is provided
may be made of a lower thermal conductivity material, such as
aluminum or plastic. The tube 25 may be filled with cooling liquid
at a relatively low level, e.g., between a bottom end of the
separation wall 23 and an upper end of the wall, since the
evaporation channels 22 need not be completely flooded.
[0056] FIG. 14 shows yet another illustrative embodiment of a
thermosiphon device 10. In this embodiment, a condenser section 1
having multiple condensing channel 12 extends between upper and
lower headers 3, which may be arranged like that shown in FIG. 4.
Upper and lower connecting tubes 19 and 35 may fluidly connect
multiple headers 3, if provided. An evaporation section 2 includes
a tube, e.g., a flat, multi-channel tube, that extends from the
lower tube 35 to the upper tube 19. A liquid return path 21 extends
from the lower tube 35 and provides liquid to a heat receiving area
5 of the evaporator section 2, e.g., where one or more evaporation
channels 22 is provided. Vapor produced at the heat receiving area
5 flows upwardly to the upper tube 19, where the vapor enters the
condensing channels 12.
[0057] The embodiments provided herein are not intended to be
exhaustive or to limit the invention to a precise form disclosed,
and many modifications and variations are possible in light of the
above teachings. The embodiments were chosen and described in order
to best explain the principles of the invention and its practical
application to thereby enable others skilled in the art to best
utilize the invention in various embodiments and with various
modifications as are suited to the particular use contemplated.
Although the above description contains many specifications, these
should not be construed as limitations on the scope of the
invention, but rather as an exemplification of alternative
embodiments thereof
[0058] The indefinite articles "a" and "an," as used herein in the
specification and in the claims, unless clearly indicated to the
contrary, should be understood to mean "at least one."
[0059] The phrase "and/or," as used herein in the specification and
in the claims, should be understood to mean "either or both" of the
elements so conjoined, i.e., elements that are conjunctively
present in some cases and disjunctively present in other cases.
Multiple elements listed with "and/or" should be construed in the
same fashion, i.e., "one or more" of the elements so conjoined.
Other elements may optionally be present other than the elements
specifically identified by the "and/or" clause, whether related or
unrelated to those elements specifically identified.
[0060] The use of "including," "comprising," "having,"
"containing," "involving," and/or variations thereof herein, is
meant to encompass the items listed thereafter and equivalents
thereof as well as additional items.
[0061] It should also be understood that, unless clearly indicated
to the contrary, in any methods claimed herein that include more
than one step or act, the order of the steps or acts of the method
is not necessarily limited to the order in which the steps or acts
of the method are recited.
[0062] While aspects of the invention have been described with
reference to various illustrative embodiments, such aspects are not
limited to the embodiments described. Thus, it is evident that many
alternatives, modifications, and variations of the embodiments
described will be apparent to those skilled in the art.
Accordingly, embodiments as set forth herein are intended to be
illustrative, not limiting. Various changes may be made without
departing from the spirit of aspects of the invention.
* * * * *