U.S. patent application number 13/831902 was filed with the patent office on 2013-10-17 for gas-to-water heat exchanger.
This patent application is currently assigned to ECONOTHERM UK LIMITED. The applicant listed for this patent is ECONOTHERM UK LIMITED. Invention is credited to Dumitru Fetcu.
Application Number | 20130269912 13/831902 |
Document ID | / |
Family ID | 49324034 |
Filed Date | 2013-10-17 |
United States Patent
Application |
20130269912 |
Kind Code |
A1 |
Fetcu; Dumitru |
October 17, 2013 |
GAS-TO-WATER HEAT EXCHANGER
Abstract
A heat exchanger is disclosed for cooling a gas from a first
temperature to a second temperature. The exchanger comprises a
first heat exchanging chamber, a second heat exchanging chamber and
an array of heat pipes which are arranged to extend from within the
first heat exchanging chamber to within the second heat exchanging
chamber. The first heat exchanging chamber comprises an inlet for
receiving a coolant into the chamber and an outlet through which
the coolant can exit the first chamber, the coolant being arranged
to pass over the portion of the heat pipes which extend within the
first chamber. The second heat exchanging chamber comprises an
inlet for receiving the gas at a first temperature into the chamber
and an outlet through which the gas can exit the second chamber at
a second temperature. The gas is arranged to pass along the second
chamber between the inlet and the outlet, along a path comprising a
substantially constant cross-sectional area to minimize the
pressure drop between the inlet and the outlet.
Inventors: |
Fetcu; Dumitru; (Cardiff,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ECONOTHERM UK LIMITED; |
|
|
US |
|
|
Assignee: |
ECONOTHERM UK LIMITED
Bridgend
GB
|
Family ID: |
49324034 |
Appl. No.: |
13/831902 |
Filed: |
March 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61612251 |
Mar 17, 2012 |
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Current U.S.
Class: |
165/104.14 |
Current CPC
Class: |
F28F 27/02 20130101;
F28D 15/0275 20130101; F28F 2265/26 20130101; F28D 15/02 20130101;
F28D 21/0003 20130101 |
Class at
Publication: |
165/104.14 |
International
Class: |
F28D 15/02 20060101
F28D015/02 |
Claims
1. A heat exchanger for cooling a gas from a first temperature to a
second temperature, the exchanger comprising a first heat
exchanging chamber, a second heat exchanging chamber and an array
of heat pipes which are arranged to extend from within the first
heat exchanging chamber to within the second heat exchanging
chamber; the first heat exchanging chamber comprising an inlet for
receiving a coolant into the chamber and an outlet through which
the coolant can exit the first chamber, the coolant being arranged
to pass over the portion of the heat pipes which extend within the
first chamber; the second heat exchanging chamber comprising an
inlet for receiving the gas at a first temperature into the chamber
and an outlet through which the gas can exit the second chamber at
a second temperature; wherein, the gas is arranged to pass along
the second chamber between the inlet and the outlet along a path
comprising a substantially constant cross-sectional area to
minimize the pressure drop between the inlet and the outlet.
2. A heat exchanger according to claim 1, further comprising a
deflection plate which is arranged to deflect the passage of gas
across the heat pipes in passing between the inlet and the outlet
of the second chamber.
3. A heat exchanger according to claim 2, wherein the deflection
plate is arranged to cause the gas to pass predominantly across the
heat pipes as opposed to along the heat pipes.
4. A heat exchanger according to claim 2, wherein the deflection
plate extends substantially radially of the second chamber and
comprises an outer periphery which is spaced from a side wall of
the second chamber.
5. A heat exchanger according to claim 2, wherein the deflection
plate comprises a gate disposed therein which is arranged to open
and close a central region of the deflection plate.
6. A heat exchanger according to claim 5, wherein the outlet of the
first chamber comprises a sensor for sensing the temperature of the
liquid exiting the first chamber.
7. A heat exchanger according to claim 6, wherein the gate is
arranged to open and close in dependence on the sensed temperature
of the liquid exiting the first chamber.
8. A heat exchanger according to claim 1, wherein the inlet and
outlet of the second chamber are disposed on a longitudinal axis of
the heat exchanger.
9. A heat exchanger according to claim 1, wherein the array of heat
pipes comprises heat pipes arranged in substantially concentric
circular rows.
10. A heat exchanger according to claim 1, wherein the heat pipes
are orientated substantially parallel to each other.
11. A heat exchanger according to claim 1, wherein the rows of heat
pipes comprise a plurality of flow disturbers disposed at separated
positions along the rows and which serve to create a turbulent flow
of liquid within the row.
12. A heat exchanger according to claim 11, wherein the flow
disturbers comprise a plurality of rods which extend along the
length of the first chamber substantially parallel to the heat
pipes.
13. A heat exchanger according to claim 12, wherein successive rods
along each row are disposed at opposite sides of the row to
redirect the flow of liquid along the row.
14. A heat exchanger according claim 1, wherein the first and
second heat exchanging chambers are separated by a separation
plate, through which the heat pipes extend.
15. A heat exchanger according to claim 14, wherein the heat pipes
extend in sealing relation with the separation plate via sealing
means.
16. A heat exchanger according to claim 15, wherein the sealing
means comprises a collar separately disposed around each heat pipe
which is arranged to compress a sealing ring against the separation
plate.
17. A heat exchanger according to claim 1, wherein the first
chamber further comprises a compression plate disposed above the
heat pipes, which is arranged to abut the upper region of the heat
pipes at one side thereof and comprises a plurality of compression
springs disposed on the other side thereof.
18. A heat exchanger according to claim 17, wherein the compression
springs are arranged to extend against a lid of the first chamber
and act to urge the compression plate against the heat pipes and
thus the heat pipes within the separation plate.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This non-provisional application claims the benefit of
provisional application No. 61/612,251 filed on Mar. 17, 2012,
entitled "Gas-to-Water Heat Exchanger", including Appendix A, which
application and appendix are incorporated herein in their entirety
by this reference.
BACKGROUND
[0002] The present invention relates to a heat exchanger and
particularly, but not exclusively to a heat exchanger comprising
heat pipes.
[0003] A heat pipe is a hermetically sealed evacuated tube
typically comprising a mesh or sintered powder wick and a working
fluid in both the liquid and vapour phase. When one end of the tube
is heated the liquid turns to vapour upon absorbing the latent heat
of vaporization. The hot vapour subsequently passes to the cooler
end of the tube where it condenses and gives out the latent heat to
the tube. The condensed liquid then flows back to the hot end of
the tube and the vaporization-condensation cycle repeats. Since the
latent heat of vaporization is usually very large, considerable
quantities of heat can be transported along the tube and a
substantially uniform temperature distribution can be achieved
along the heat pipe.
[0004] It is known to utilize a heat exchanger comprising separated
chambers and a plurality of heat pipes which extend between the
chambers, such that heat can become transferred from one chamber to
the other. In this respect, by passing a heated fluid through one
chamber, the heat pipes can transfer the heat absorbed from the
heated fluid to the other chamber wherein a cooled fluid may pass
to subsequently absorb the heat from the heat pipes.
[0005] However, when passing a fluid through a chamber of the heat
exchanger it is found that the pressure drop between an inlet and
an outlet of the respective chamber can be significant. This is
found to reduce the heat transfer efficiency between the fluid and
the heat pipes within the chamber with the result that the heat can
rapidly increase to dangerous levels within the chamber.
SUMMARY
[0006] We have now devised an improved heat exchanger which
alleviates the above-mentioned problem.
[0007] In accordance with the present invention, there is provided
a heat exchanger for cooling a gas from a first temperature to a
second temperature, the exchanger comprising a first heat
exchanging chamber, a second heat exchanging chamber and an array
of heat pipes which are arranged to extend from within the first
heat exchanging chamber to within the second heat exchanging
chamber;
[0008] the first heat exchanging chamber comprising an inlet for
receiving a coolant into the chamber and an outlet through which
the coolant can exit the first chamber, the coolant being arranged
to pass over the portion of the heat pipes which extend within the
first chamber;
[0009] the second heat exchanging chamber comprising an inlet for
receiving the gas at a first temperature into the chamber and an
outlet through which the gas can exit the second chamber at a
second temperature; wherein,
[0010] the gas is arranged to pass along the second chamber between
the inlet and the outlet along a path comprising a substantially
constant cross-sectional area to minimize the pressure drop between
the inlet and the outlet.
[0011] The provision of a substantially uniform cross-sectional
area for the gas flow reduces regions of significant pressure
gradients within the chamber. The heat exchanger of the present
invention thus ensures a minimal pressure drop and thus a
substantially uniform transfer of heat between the gas and the heat
pipes at all positions within the chamber.
[0012] Preferably, the second heat exchanging chamber further
comprises a deflection plate which is arranged to deflect the
passage of gas across the heat pipes in passing between the inlet
and the outlet of the second chamber. The deflection plate is
arranged to cause the gas to pass predominantly across the heat
pipes as opposed to along the heat pipes to increase the thermal
transfer between the heat pipes and the gas and thus the thermal
transfer between the first and second chambers.
[0013] The deflection plate preferably extends substantially
radially of the second chamber and comprises an outer periphery
which is spaced from a side wall of the second chamber. The gas is
thus arranged to pass through an annular aperture defined between
the outer periphery of the deflection plate and the side wall of
the chamber, in passing between the inlet and the outlet of the
second chamber.
[0014] The inlet and outlet of the second chamber are preferably
disposed on a longitudinal axis of the heat exchanger.
[0015] Preferably, the deflection plate comprises a gate disposed
therein which is arranged to open and close a central region of the
deflection plate. The gate serves as a valve to control the passage
of gas direct from the inlet to the outlet of the second chamber,
through the plate. The gate preferably comprises a butterfly
valve.
[0016] The outlet of the first chamber preferably comprises a
sensor for sensing the temperature of the liquid exiting the first
chamber. The gate is preferably arranged to open and close in
dependence on the sensed temperature of the liquid exiting the
first chamber.
[0017] Preferably, the array of heat pipes comprises heat pipes
arranged in substantially concentric circular rows. The heat pipes
are preferably orientated substantially parallel to each other.
[0018] The rows of heat pipes preferably comprise a plurality of
flow disturbers disposed at separated positions along the rows and
which serve to create a turbulent flow of liquid within the row.
The flow disturbers preferably comprise a plurality of rods which
extend along the length of the first chamber substantially parallel
to the heat pipes. Successive rods along each row are preferably
disposed at opposite sides of the row to redirect the flow of
liquid along the row.
[0019] The first and second heat exchanging chambers are preferably
separated by a separation plate, through which the heat pipes
extend. Preferably, the heat pipes extend in sealing relation with
the separation plate via sealing means. Preferably, the sealing
means comprises a collar separately disposed around each heat pipe
which is arranged to compress a sealing ring against the separation
plate.
[0020] The first chamber preferably further comprises a compression
plate disposed above the heat pipes, which is arranged to abut the
upper region of the heat pipes at one side thereof and comprises a
plurality of compression springs disposed on the other side
thereof.
[0021] The compression springs are preferably arranged to extend
against a lid of the first chamber and act to urge the compression
plate against the heat pipes and thus the heat pipes within the
separation plate. During operation of the heat exchanger the
temperature of the heat pipes will increase and it is found that
this temperature increase causes a small expansion of the heat
pipes. The compression plate and springs enable the heat pipes to
freely expand while maintaining a bias of the heat pipes toward the
separation plate.
[0022] Note that the various features of the present invention
described above may be practiced alone or in combination. These and
other features of the present invention will be described in more
detail below in the detailed description of the invention and in
conjunction with the following figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] In order that the present invention may be more clearly
ascertained, some embodiments will now be described, by way of
example, with reference to the accompanying drawings, in which:
[0024] FIG. 1 is a longitudinal sectional view of a heat exchanger
according to an embodiment of the present invention;
[0025] FIG. 2 is a transverse sectional view of the heat exchanger
of FIG. 1 taken across line A-A;
[0026] FIG. 3 is a transverse sectional view of the heat exchanger
of FIG. 1 taken along line B-B;
[0027] FIG. 4 is a plan view of the baffle disposed within the
second chamber;
[0028] FIG. 5 is a magnified longitudinal sectional view of a heat
pipe disposed within a separation plate, illustrating the sealing
means;
[0029] FIG. 6 is a magnified view of a spring disposed upon the
compression plate; and
[0030] FIG. 7 is a transverse sectional view of the heat exchanger
of FIG. 1 taken across line B-B, with side walls of the heat
exchanger opened.
DETAILED DESCRIPTION
[0031] The present invention will now be described in detail with
reference to several embodiments thereof as illustrated in the
accompanying drawings. In the following description, numerous
specific details are set forth in order to provide a thorough
understanding of embodiments of the present invention. It will be
apparent, however, to one skilled in the art, that embodiments may
be practiced without some or all of these specific details. In
other instances, well known process steps and/or structures have
not been described in detail in order to not unnecessarily obscure
the present invention. The features and advantages of embodiments
may be better understood with reference to the drawings and
discussions that follow.
[0032] Referring to FIGS. 1 to 3 of the drawings, there is
illustrated a heat exchanger according to an embodiment of the
present invention. The heat exchanger 10 comprises a first heat
exchanging chamber 11 and a second heat exchanging chamber 12. Each
chamber 11, 12 comprises a substantially cylindrical housing 13,
14, which are mounted one on top of the other such that a
longitudinal axis of the first chamber 11 extends in a
substantially collinear relationship with a longitudinal axis of
the second chamber 12 and thus the heat exchanger 10.
[0033] The first chamber 11 of the heat exchanger 10 is disposed
above the second chamber 12 and comprises an inlet 15 and an outlet
16 which are disposed within an arcuate side wall of the housing
13. The inlet and outlet 15, 16 of the first chamber 11 are
arranged to enable a liquid coolant such as water, to pass into and
out from the chamber 11, respectively. The first chamber 11 further
comprises a passage 17 which extends along the first chamber 11
substantially along the longitudinal axis thereof. The passage 17
is defined by a substantially cylindrical wall 18 which seals the
interior of the first chamber 11 from the passage 17, and extends
between an opening 19 disposed in an upper end wall 20 of the first
chamber 11 to an upper region of a separation plate 21.
[0034] Referring to FIG. 4 of the drawings, the separation plate 21
comprises a first aperture 22 disposed substantially at the centre
thereof which is arranged to align with the cylindrical wall 18
defining the passage 17, such that the wall 18 extends
substantially around a periphery of the first aperture 22. The
second chamber 12 is secured to the underside of the separation
plate 21 and thus the first chamber 11, and comprises an inlet 23
disposed substantially upon the longitudinal axis of the chamber
12, within a lower end wall 24 thereof. The first aperture 22
disposed within the separation plate 21 and the passage 17 serve as
an outlet of the second chamber 12, such that the gas to be cooled
for example, is arranged to pass into the second chamber 12 through
the inlet 23 disposed in the lower end wall 24 of the second
chamber 11 and out of the second chamber through the first aperture
22 and along the passage 17.
[0035] The heat exchanger 10 further comprises a plurality of
substantially linear heat pipes 25 which extend from within the
first chamber 11, through an array of second apertures 26 disposed
within the separation plate 21 around the first aperture 22, and
terminate in the second chamber 12 so as to enable heat to be
transferred between the chambers 11, 12. The heat pipes 25 extend
substantially parallel to the longitudinal axis of the first and
second chambers 11, 12 and are configured in a substantially
concentric arrangement of rows of heat pipes 25, as illustrated in
FIGS. 2 and 3 of the drawings, centered substantially on the
longitudinal axis. In this manner each chamber 11, 12 comprises a
plurality of arcuate rows of heat pipes 25, having different radii
of curvature.
[0036] Adjacent circular rows of heat pipes 25 within the first
chamber 11 are separated by a wall 26 which extends along the
length of the first chamber 11 and defines a channel 27 along which
the liquid can flow. Adjacent walls 26 comprise an aperture 28
disposed at opposite ends thereof such that the liquid is cause to
flow in a clockwise direction, for example, within the channel 27
in passing across one row of heat pipes 25 substantially around the
chamber 11, before passing radially of the chamber 11 to the
adjacent row of heat pipes 25, and subsequently in a
counter-clockwise direction in passing across the heat pipes 25 in
the adjacent row.
[0037] The channel 27 disposed in the first chamber 11 further
comprises a plurality of rods 29 which extend substantially
parallel to each other and the longitudinal axis of the heat
exchanger 10. The rods 29 are disposed along the channel 27 between
the heat pipes 25, and successive rods 29 along the channel 27 are
disposed at opposite sides of the channel 27 to prevent the liquid
from simply passing around a side of the channel 27 without
significantly extracting the heat from the heat pipes 25. The rods
27 act to create a turbulent flow within the channel 27 and thus
encourage the interaction of the liquid with the heat pipes 25 to
maximize the transfer of heat between the heat pipes 25 and the
liquid.
[0038] The second chamber 12 comprises a deflection plate or baffle
30 which extends across the chamber 12, substantially transverse
the longitudinal axis of the chamber 12, between the inlet 23 and
the outlet region defined by the first aperture 17 in the
separation plate 21. The baffle 30 extends substantially radially
of the second chamber 12 from a central region thereof, and
comprises an outer periphery which is spaced from the housing 14 of
the second chamber 12 to define an annular passage 31. The heat
pipes 25 are arranged to extend through apertures 30a in the baffle
30 in sealing relation therewith, such that the gas is arranged to
pass across the heat pipes 25, through the annular passage 31, and
back across the heat pipes 25, in moving from the inlet 23 to the
outlet region of the second chamber 12.
[0039] The baffle 30 comprises a gate or valve 32, such as a
butterfly valve, which can be configured between a fully open state
in which the gas is arranged to pass direct from the inlet 23 to
the outlet region without substantially passing through the annular
passage 31, a closed state in which the majority of the gas is
arranged to pass through the annular passage 31 in passing from the
inlet 23 to the outlet region of the second chamber 12, and various
intermediate states in which a portion of the gas is arranged to
pass through the valve 32 and a portion of the gas is arranged to
pass through the annular passage 31. The cross-sectional area of
the annular passage 31 is substantially matched to the
cross-sectional area of the inlet 23 and outlet region of the
second chamber 12 to minimize the pressure drop of the gas between
the inlet 23 and outlet region of the second chamber 12.
[0040] Referring to FIG. 5 of the drawings, the heat pipes 25 are
supported within the heat exchanger 10 by the separation plate 21
via a series of collars 33 disposed upon the heat pipes 25. The
collars 33 are arranged to extend within each of the second
apertures 26 and serve to seal the heat pipes 25 to the separation
plate 21, such that the interior of the first and second chambers
11, 12 remain isolated from each other.
[0041] The second apertures 26 comprise an internal flange 34 which
extends into the respective second aperture 26 to reduce the
diameter of the second aperture 26 at the side of the plate 21
adjacent the second chamber 12. The flanges 34 separately act as a
seat for a sealing ring 35, such as an O-ring, such that the
collars 33 separately disposed upon the heat pipes 25 are arranged
to extend into the respective aperture 26 from within the first
chamber 11 and compress the sealing ring 35 against the flange 34
and the heat pipe 25, to seal the heat pipe 25 within the
separation plate 21.
[0042] The longitudinal ends of the heat pipes 25 disposed within
the second chamber 12 are uncoupled and separated from the lower
end wall 24 of the second chamber 12, whereas the longitudinal end
of the heat pipes 25 disposed within the first chamber are arranged
to abut the underside of a compression plate 36. The compression
plate 36 is substantially annular in shape, and is sized to extend
between the cylindrical wall 18 defining the passage 17 and the
arcuate side walls 13 of the first chamber 11.
[0043] The upper side of the compression plate 36 comprises a
plurality of compression springs 37 which are arranged to abut the
upper wall 20 of the first chamber 11, as illustrated in FIG. 6 of
the drawings. When the upper wall 20 is secured upon the first
chamber 11 to seal the first chamber 11, the springs 37 are
arranged to partially compress to urge the compression plate 36
upon the upper ends of the heat pipes 25 and thus bias the heat
pipes 25 into the second apertures 26 to maintain the seal between
the heat pipes 25 and the separation plate 21. During use it is
found the increase in temperature of the heat pipes 25 causes the
heat pipes 25 to expand which can cause thermal stresses to develop
within the heat exchanger 10. The compression plate 36 and springs
37 enable the heat pipes to expand to relieve any stresses which
develop, while maintaining an intimate seal of the heat pipes
within the second apertures of the separation plate 21.
[0044] In use, the gas to be cooled is arranged to pass into the
second chamber 12 via the inlet 23 and subsequently pass radially
outwardly across the heat pipes 25 due to the baffle 30, through
the annular passage 31. The gas is then caused to pass radially
inwardly of the second chamber 12, back across the heat pipes 25
toward the outlet region. As the gas passes across the heat pipes
25, the heat associated with the gas becomes transferred to the
heat pipes 25, causing the gas to become cooled. The heat
transferred to the heat pipes 25 is then communicated along the
heat pipes 25 to the first chamber and becomes extracted therefrom
by the flow of liquid, for example water, within the channel 27.
The outlet 16 of the first chamber comprises a sensor (not shown),
for example a thermocouple sensor, for sensing the temperature of
the liquid exiting the chamber 11. If the monitored temperature of
the liquid rises above a threshold value, then in order to control
the amount of heat recovered from the gas, the valve 32 on the
baffle 30 is opened accordingly to vent a portion of the gas direct
to the outlet region and thus reduce the amount of heat transferred
between the gas and the heat pipes 25.
[0045] Referring to FIG. 7 of the drawings, the arcuate walls 14 of
the second chamber 12 may be hinged or otherwise removable from the
heat exchanger to provide for access into the chamber 12 for
cleaning and maintenance. The skilled reader will recognize
however, that the arcuate side walls 13 of the first chamber 11 may
also be hinged or removable for cleaning and maintenance.
[0046] For further details of the present invention, please see
attached Appendix A.
[0047] While this invention has been described in terms of several
embodiments, there are alterations, modifications, permutations,
and substitute equivalents, which fall within the scope of this
invention. It should also be noted that there are many alternative
ways of implementing the methods and apparatuses of the present
invention. It is therefore intended that the following appended
claims be interpreted as including all such alterations,
modifications, permutations, and substitute equivalents as fall
within the true spirit and scope of the present invention.
* * * * *