U.S. patent number RE46,343 [Application Number 13/506,713] was granted by the patent office on 2017-03-21 for indirect evaporative cooling heat exchanger.
This patent grant is currently assigned to THE MUNTERS CORPORATION. The grantee listed for this patent is Nicholas H. Des Champs. Invention is credited to Nicholas H. Des Champs.
United States Patent |
RE46,343 |
Des Champs |
March 21, 2017 |
Indirect evaporative cooling heat exchanger
Abstract
A heat exchanger including a header having a plurality of header
openings with rigid tubes that may be made of plastic are inserted
in the openings. The tubes are sealed to the header to prevent
leakage between the header and the tubes to prevent water and air
leakage between the wet, scavenger air stream flowing through the
tubes and a dry air stream flowing around the tubes. A method of
making the heat exchanger includes providing the openings with a
flange and uses an interference fit between the rigid heat exchange
tubes and the header openings. A self-leveling sealant may be used
to seal the heat exchanger tubes to the header using, for example,
a paint roller and/or a paint sprayer.
Inventors: |
Des Champs; Nicholas H. (Las
Vegas, NV) |
Applicant: |
Name |
City |
State |
Country |
Type |
Des Champs; Nicholas H. |
Las Vegas |
NV |
US |
|
|
Assignee: |
THE MUNTERS CORPORATION
(Amesbury, MA)
|
Family
ID: |
35423685 |
Appl.
No.: |
13/506,713 |
Filed: |
May 11, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
10853160 |
Oct 31, 2006 |
7128138 |
|
|
Reissue of: |
11366749 |
Mar 3, 2006 |
7716829 |
May 18, 2010 |
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28F
9/14 (20130101); F24F 1/0043 (20190201); B23P
15/26 (20130101); F28F 9/162 (20130101); F28F
1/40 (20130101); F28C 3/08 (20130101); F28F
9/14 (20130101); F24F 1/0007 (20130101); F24F
1/0059 (20130101); F28F 1/40 (20130101); F24F
1/0059 (20130101); F28F 21/062 (20130101); B23P
15/26 (20130101); F28F 9/162 (20130101); F28F
21/062 (20130101); Y10T 29/49377 (20150115); Y10T
29/49377 (20150115); Y10T 29/49364 (20150115); Y10T
29/4935 (20150115); Y10T 29/49359 (20150115); Y10T
29/49384 (20150115); Y10T 29/4938 (20150115); Y10T
29/49373 (20150115); Y10T 29/49378 (20150115); Y02B
30/54 (20130101); Y10T 29/49364 (20150115); Y10T
29/4938 (20150115); Y10T 29/49384 (20150115); Y02B
30/54 (20130101); Y10T 29/49373 (20150115); Y10T
29/49359 (20150115); F24F 1/0007 (20130101); Y10T
29/49378 (20150115); Y10T 29/4935 (20150115) |
Current International
Class: |
B21D
39/08 (20060101); F28F 9/14 (20060101); F28F
9/16 (20060101); F28F 21/06 (20060101); F28F
1/40 (20060101); B23P 15/26 (20060101); F28F
9/04 (20060101); B21D 53/02 (20060101); F24F
1/00 (20110101) |
Field of
Search: |
;29/890.044,890.047,890.03,890.035,890.038,890.043,890.045,890.046
;122/18.2 ;165/46,229,84 ;277/596 ;261/112.1,153 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Aztec Cooling, Jun. 21, 2006, [online], [retrieved on May 6, 2004]
Retrieved from the Aztec Sensible Cooling website using Internet
URL: http://www.mestek.com/companies/Aztec.html. cited by applicant
.
Indirect Evaporative Cooling, [online], [retrieved May 26, 2004]
Retrieved using Internet URL: http://www.espnw.com/QDT/IDEC.html.
cited by applicant .
Indirect Evaporative Cooling, [online], [retrieved May 25, 2004]
Retrieved using the Energy Labs Inc. website using Internet URL:
http://www.energylabs.com/web/components.asp?OP=Indirect.sub.--Evaporativ-
e.sub.--Cooling. cited by applicant .
Indirect/Direct Multiple Stages of Cooling, [online], [retrieved
May 26, 2004] Retrieved using Internet URL:
http://www.specair.net/stageii.html. cited by applicant .
Sep. 30, 2014 Office Action issued in U.S. Appl. No. 13/901,757.
cited by applicant .
Oct. 6, 2014 Office Action issued in U.S. Appl. No. 13/901,769.
cited by applicant.
|
Primary Examiner: Doerrler; William
Attorney, Agent or Firm: Oliff PLC
Parent Case Text
.[.This is a Division of application Ser. No. 10/853,160 filed May
26, 2004. The entire disclosure of the prior application is hereby
incorporated by reference herein in its entirety..]. .Iadd.More
than one reissue application has been filed for the reissuance of
U.S. Pat. No. 7,716,829. Reissue application Ser. No. 13/901,769,
filed on May 24, 2013, is a reissue divisional of the present
application. Reissue application Ser. No. 13/901,757, filed on May
24, 2013, is a reissue continuation of the present application. The
present application (Ser. No. 13/506,713, filed on May 11, 2012) is
an application for reissuance of U.S. Pat. No. 7,716,829, which is
a continuation of application Ser. No. 10/853,160, now U.S. Pat.
No. 7,128,138. The entire disclosure of application Ser. No.
10/853,160 is hereby incorporated by reference herein in its
entirety..Iaddend.
Claims
What is claimed is:
1. A method of sealing a plurality of rigid tubes to a metal header
having a plurality of openings therethrough, comprising: forming a
flange into each of the openings in the header; inserting the rigid
tubes into the openings in the header, the header having an
exterior surface and an interior surface and the rigid tubes having
a top portion and a bottom portion, the rigid tubes are inserted
with the bottom portion first, and are placed into the openings of
the header so that the top portion of the rigid tubes are
substantially flush with the exterior surface of the header; and
applying a sealant to the exterior surface of the header and the
inserted rigid tubes by an absorbent applicator and/or a spray
applicator.
2. The method of claim 1, wherein applying the sealant includes
rolling an adhesive over the header.
3. The method of claim 1, wherein at least one groove is provided
in the tubes.
4. The method of claim 1, wherein an end surface of the rigid tubes
is angled with respect to a bottom end portion of the rigid
tubes.
5. The method of claim 1, wherein an end surface of the rigid tubes
has a compound angle with respect to a bottom end portion of the
rigid tubes.
6. The method of claim 4, wherein the end surface of the rigid
tubes is angled at approximately 20 to 30 degrees from the
horizontal.
7. The method of claim 1, wherein the sealant is a self-leveling
adhesive.
8. The method of claim 1, wherein the flange extends in a direction
perpendicular from the exterior surface of the header.
9. The method of claim 1, further comprising providing each of the
openings with a flange before inserting the rigid tubes, wherein
the flange extends in a direction perpendicular from the
substantially uniform exterior surface of the header.
10. The method of claim 1, further comprising providing each of the
openings with a flange before inserting the rigid tubes, wherein
the flange extends in a direction perpendicular from the
substantially planar exterior surface of the header.
.Iadd.11. A method of operating a heat exchanger, comprising:
evaporatively cooling a plurality of rigid tubes by contacting the
rigid tubes with water and a first air stream to cause water
evaporation; cooling air by contacting a second air stream with the
evaporatively cooled rigid tubes to cool the air of the second air
stream; and causing the rigid tubes to expand and contract within a
predetermined range to separate solid deposits accumulating on the
rigid tubes as a result of water evaporation by changing a pressure
of the rigid tubes by varying a speed of air contacting the rigid
tubes, wherein ends of the rigid tubes are sealed in a leak tight
manner to openings formed within a header of the heat
exchanger..Iaddend.
.Iadd.12. The method of claim 11, further comprising: collecting
solid deposits separated from the plurality of rigid tubes in a
sump; and flushing the solid deposits from the sump..Iaddend.
.Iadd.13. The method of claim 11, wherein the plurality of rigid
tubes are formed from a plastic material..Iaddend.
.Iadd.14. The method of claim 13, wherein the plastic material
comprises polyvinylchloride..Iaddend.
.Iadd.15. The method of claim 11, wherein the plurality of rigid
tubes comprise corrosion resistant polymers having a fire and smoke
retardant rating that meets or exceeds UL94 V-O or V-l
rating..Iaddend.
.Iadd.16. The method of claim 11, wherein the expansion and
contraction of the plurality of rigid tubes within the
predetermined range is caused by changes in an internal pressure of
the plurality of rigid tubes..Iaddend.
.Iadd.17. The method of claim 16, wherein the changes in the
internal pressure of the plurality of rigid tubes are caused by
varying a speed of the air flowing through an interior of the
plurality of rigid tubes..Iaddend.
.Iadd.18. The method of claim 16, wherein the changes in the
internal pressure of the plurality of rigid tubes are in a range of
up to 0.5 inches of water column pressure..Iaddend.
.Iadd.19. The method of claim 11, wherein the predetermined range
is up to 0.025 inches..Iaddend.
.Iadd.20. The method of claim 11, wherein the plurality of rigid
tubes have a wall thickness of about 0.020 inches..Iaddend.
.Iadd.21. The method of claim 11, wherein the plurality of rigid
tubes have an internal web structure to flexibly maintain tube
dimensions, and to maintain the expansion and contraction of the
plurality of rigid tubes within the predetermined
range..Iaddend.
.Iadd.22. The method of claim 11, wherein the plurality of rigid
tubes are sealed to the header by an adhesive..Iaddend.
.Iadd.23. The method of claim 11, wherein the plurality of rigid
tubes are sealed to the header by a self-leveling
liquid..Iaddend.
.Iadd.24. The method of claim 11, wherein the plurality of rigid
tubes include grooves formed on the internal surface to provide
increased surface area and reduce thermal resistance..Iaddend.
.Iadd.25. The method of claim 11, wherein individual tubes of the
plurality of rigid tubes have openings at both ends..Iaddend.
.Iadd.26. The method of claim 11, wherein the water and first air
stream flow in opposite directions..Iaddend.
.Iadd.27. The method of claim 11, wherein the plurality of rigid
tubes are non-cylindrical tubes..Iaddend.
.Iadd.28. The method of claim 27, wherein the non-cylindrical tubes
are ovoid tubes..Iaddend.
.Iadd.29. The method of claim 11, wherein the method is performed
within an evaporative cooling unit including the heat exchanger,
and the evaporative cooling unit provides water and air to the heat
exchanger..Iaddend.
.Iadd.30. The method of claim 29, wherein the evaporative cooling
unit is an indirect evaporative cooling unit..Iaddend.
.Iadd.31. The method of claim 29, wherein the evaporative cooling
unit is an indirect/direct evaporative cooling unit that comprises
a direct cooling stage..Iaddend.
Description
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to indirect evaporative cooling technology,
and particularly to heat exchangers useful in indirect evaporative
cooling devices used for conditioning air.
2. Description of Related Art
Evaporative cooling involves lowering the temperature of a liquid
by utilizing the latent heat of vaporization of a portion of the
liquid. The term "Indirect Evaporative Cooling" was coined by
personnel at Des Champs Laboratories in 1974, when they decided to
enhance summer-time air-to-air energy recovery, from building
exhaust air, by utilizing the wet bulb temperature of the exhaust
air instead of the higher dry bulb temperature. At the time, it was
common practice during summer months to transfer energy from the
cooler exhaust air to the warm, outdoor, make-up air by using an
air-to-air heat exchanger. The driving force that causes the
transfer of energy within the heat exchanger, in the aforementioned
process, is the sensible temperature difference between the two air
streams. During summer months, the outdoor air that is delivered to
a space, and the recirculated internal air, are usually
air-conditioned. As a result, the air within the space has a lower
wet bulb temperature than the outdoor air or the inside dry bulb
temperature.
By spraying water on the surface of the exhaust side of the
air-to-air heat exchanger during the cooling season, the exhaust
air flow, at a low wet bulb temperature, evaporates water from that
exhaust side surface and thereby attempts to drive the
water/exhaust-side surface temperature lower, approaching the
exhaust air wet-bulb temperature at the limit. The supply air,
flowing on the other side of the membrane that separates the two
air streams, comes in contact with a surface (the opposite side of
the membrane from the exhaust side) that is much cooler and
consequently more energy is transferred between air streams and
thus a greater energy saving occurs. The reason the surface is
cooler than it would otherwise be is because of the evaporative
cooling that takes place at the exhaust air/water layer interface,
which in turn manifests itself as a cooler membrane temperature
than would exist if the exhaust air were simply left dry with no
water spray. As a matter of interest is the fact that the
temperature drop across the membrane, from the exhaust-side surface
to the supply-side surface, is very small, i.e., on the order of a
fraction of a degree while the typical temperature difference
between the two bulk air streams is on the order of 10 to 40
F..degree..
Early indirect evaporative cooling (IEC) units were simply a
modification of standard air-to-air heat exchangers that were used
to extract energy (or lack of energy) from the exhaust air and
transfer it to fresh, incoming make-up air, thus reducing the
energy that would otherwise be required to condition the outdoor
air prior to delivering it to the occupied space. Consequently, the
heat transfer devices used in the early IEC units were designed to
transfer energy in a dry environment. In contrast, more recent IEC
units are subjected to a wet environment. Such wet environments are
known to contain a wide range of contaminants and are often
corrosive to IEC components. As a result of the hostile environment
that such IEC heat exchangers witnessed, they were maintenance
prone and short lived. Consequently, IECs, after getting off to an
admirable start in the late 1970s and early 1980s, languished in
the 1990s and, so far, into the new century even though IECs have
the potential for tremendous energy savings and reduction in peak
summer electrical demand.
Additionally, known heat exchangers have designs that require
lengthy assembly periods. For example, in known systems, assembly
of heat exchanger tubes to a plate or manifold requires an
individual to seal around the perimeter of each tube by hand in an
attempt to prevent leaks. This method of assembly often requires
10-20 hours to implement. Furthermore, extensive quality assurance
is also necessary due to the possibility of leaks.
SUMMARY OF THE INVENTION
The present invention is directed to improvements in indirect
evaporative cooling technology. Exemplary improvements include a
novel heat exchanger useful in indirect evaporative cooling devices
used for conditioning air. In one exemplary embodiment of the
invention, an air-to-air heat exchanger designed specifically for
use in hostile environments associated with the application of IECs
in wet environments is provided.
Because the pH level of water varies from acidic to alkaline
depending upon the geographic location of the unit, the present
invention uses materials that function properly over the varying pH
levels of water, such as, for example, plastic as a suitable
material with which to construct the IEC heat exchanger.
Additionally, because water can be very hard, i.e., have a high
mineral concentration, IEC heat exchangers according to this
invention are designed to be relatively unaffected by water
hardness and the possible resulting material build-up within the
heat exchanger.
Various embodiments of the systems and methods according to this
invention provide IEC heat exchangers that are relatively
economical to manufacture and relatively quick to assemble.
Various embodiments of the systems and methods according to this
invention provide IEC heat exchangers that are relatively no more
maintenance prone than a common air-conditioner.
Various embodiments of the systems and methods according to the
invention separately provide IEC heat exchangers that, serves
simultaneously as integral cooling towers and air-to-air heat
exchangers.
Various embodiments of the systems and methods of manufacture
according to the invention separately provide means of containing
cooling water in areas that the water is intended to be so as to
perform the necessary thermodynamic functions of an IEC heat
exchanger.
Various embodiments of the systems and methods according to the
invention separately provide IEC heat exchangers which tend not to
degrade because of high or low pH water in contact with a surface
of the heat exchanger.
Various embodiments of the systems and methods according to the
invention separately provide IEC heat exchangers that have a wet
side surface that is wettable, can be kept free of mineral deposits
even though hard water intermittently sprayed on a surface of the
heat exchanger, and can be manufactured at a cost that allows an
ICE containing the heat exchanger to compete ton for ton of air
conditioning with standard mechanical air conditioning.
Various embodiments of the systems and methods according to the
invention separately provide IEC heat exchangers that have a unique
heat exchange tube design.
Various embodiments of the systems and methods according to the
invention separately provide IEC heat exchanges having a unique
connection and/or seal between heat exchange tubes and a
header.
Various embodiments of the systems and methods according to the
invention provide IEC heat exchange methods of manufacture that
achieve relatively low cost assembly of heat exchanger components
and easy repeatability of manufacture of such components by
relatively unskilled labor.
Various embodiments of the systems and methods according to the
invention provide IEC heat exchange methods of manufacture
including angling the exchange tubes at a bottom end so that the
tubes enter a cut out portion of a header plate of the heat
exchanger with ease.
Various embodiments of the systems and methods according to the
invention provide IEC heat exchangers having an improved interface
between a heat exchange tube and a header.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a perspective view of an indirect/direct evaporative
cooling unit, including an indirect evaporative cooler heat
exchanger, according to an exemplary embodiment of the
invention;
FIG. 2 shows a perspective view of an indirect evaporative cooler,
including airflow through the heat exchanger, according to an
exemplary embodiment of the invention;
FIG. 3 shows a top view of a sealed header plate of a heat
exchanger, according to an exemplary embodiment of the
invention;
FIG. 4 shows a partial view of openings in the header plate and a
plastic tube partially inserted in an opening of the header plate,
according to an exemplary embodiment of the invention;
FIG. 5 shows a partial view of the header plate with plastic tubes
installed in header plate openings, according to an exemplary
embodiment of the invention;
FIG. 6 shows a cross-section of a sealed header plate and plastic
tube, according to an exemplary embodiment of the invention:
FIG. 7 is a schematic view of a cross-section of a plastic tube,
according to an exemplary embodiment of the invention;
FIG. 8 is a flow chart showing an exemplary method of assembly of
an IEC heat exchanger, according to an exemplary embodiment of the
invention; and
FIGS. 9A-9C show an exemplary embodiment of a tube having an angled
bottom portion, according to an exemplary embodiment of the
invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 is a perspective view of an indirect/direct evaporative
cooling unit, including an indirect evaporative cooler heat
exchanger, according to an exemplary embodiment of the invention.
As shown in FIG. 1, an indirect/direct evaporative cooling unit 1
includes, a base portion 2, a frame 3, and an air intake fan 4
mounted in a wall of the frame 3 at one end of the unit 1. The
intake fan 4 provides outside air to the unit 1. The unit 1 further
includes an exhaust grate 5 mounted in the top of the unit 1 to
allow high energy, unconditioned air to exit the unit 1.
A support frame 6 is mounted to the base portion 2 within the unit
1 to provide a mounting point for the indirect heat exchanger 10
and the direct cooling stage 7. A water distribution manifold 8 is
disposed over the indirect heat exchanger 10 and the direct cooling
stage 7 to deliver water thereto. In other words, the unit shown in
FIG. 1 includes all the devices that are necessary for proper
operation to cool an air stream, as well as the novel indirect heat
exchanger 10 according to the invention.
FIG. 2 shows a perspective view of an indirect evaporative cooler,
according an exemplary embodiment of the invention. As shown in
FIG. 2, outside air drawn into the unit 1 by the intake fan 4 flows
into air intake portions 20, 21. A first outside air stream 9
enters the heat exchanger 10 through a first air intake portion 20
and flows through heat exchanger tubes 40 (FIG. 5). The first
outside air stream 9 proceeds through the first air intake portion
20 and enters into the tubes 40 through an open bottom portion of
the tubes 40 (not shown). The first outside air stream 9 flows
upwardly through the tubes 40 toward the header plate 30.
Water from the water distribution manifold 8 is sprayed onto the
header plate 30 and into header plate openings 50 (FIGS. 3 and 4).
As the water flows downwardly through the tubes 40, the first
outside air stream 9 flows upwardly through the tubes 40. Thus, the
first outside air stream 9 serves as air that evaporatively cools
the tube 40 from within the tube 40. The first outside air stream 9
exits the heat exchanger 10 through the header plate 30 as
moistened exhaust air. The exhaust air exits the unit 1 through the
exhaust grate 5.
A second outside air stream 11 enters the heat exchanger 10 through
a second outside air intake portion 21 and flows around the outside
of the tubes 40 disposed within the heat exchanger 10. The second
outside air stream 11 does not come into direct contact with water
within the tubes 40. Therefore, the second outside air stream 11 is
cooled without having water added. The second outside air stream 11
exits the exchanger 10 as dry conditioned air 12.
In operation, the dry conditioned air 12 then may flow into a
direct cooling stage 7 (FIG. 1) comprised of a suitable high
quality evaporative medium, such as "CELDEC", available from
Munters Corporation.
FIG. 3 shows a top view of a sealed header plate, according to an
exemplary embodiment of the invention. As shown in FIG. 3, the heat
exchanger 10 includes a header plate 30 having a plurality of
header plate openings 50. In an exemplary embodiment of the
invention, the header plate 30 is comprised of a metal, such as
aluminum, or other suitable material. In a header plate 30 made of
aluminum, the header plate 30 is typically made from an 1/8-inch
thick aluminum sheet. Because aluminum is sometime corrosive to the
water used in IECs, the surface of the header 30 that is exposed to
water is coated at the time the tubes 40 are sealed into the header
30.
FIG. 4 shows a partial view of header plate openings and a plastic
tube partially inserted in an opening. As shown in the exemplary
embodiment of FIG. 4, the header plate 30 includes a plurality of
openings 50. The openings 50 in the header plate 30 include an edge
that is rolled inwardly to form a flange 60. The flange 60 provides
an interface between the header plate 30 and the tubes 40 inserted
in the openings 50.
In the exemplary embodiment of the invention, the flange 60 also
aids in the insertion of the tube 40 into the openings 50. The
flange 60 also serves to provide greater contact surface area
between the header plate 30 and the tube 40 when the tube is
installed in the header plate 30. Additionally, by providing a
header plate 30 with openings 50 having such a flange 60, a more
rigid header plate construction is achieved.
In an exemplary embodiment of the invention, the flange 60 serves
to allow for an approximately flush fit between the top of the
tubes 40 when the tubes 40 are installed in the header plate 30. By
providing such a fit between the tubes 40 and the header plate 30 a
more equal flow of cooling water delivered onto the header plate 30
from the water distribution manifold 8 and into each of the tubes
40 is achieved. Such a flow of water increases the efficiency of
the heat exchanger 10 which further optimizes the cooling
capability of the unit 1. Additionally, such a configuration
enables a sealant 70 (FIGS. 5 and 6) to be easily applied to the
surface of the header 30 after the tubes 40 are installed.
As shown in FIG. 4, the tubes 40 are inserted into the openings 50
in the header plate 30. In an exemplary embodiment of the
invention, the tubes 40 may be made of a plastic and formed by
known extrusion processes. Such plastics include, for example,
corrosion resistant polymers having a fire and smoke retardant
rating that meets or exceeds UL94 V-O or V-l rating.
FIG. 5 shows a partial view of the header plate with plastic tubes
40 installed in the openings and treated with a sealant. As shown
in FIG. 5, the tubes 40 are installed in the openings 50 of the
header plate 30. The tubes 40 may be installed by press-fitting, or
any other suitable method. Upon installation of the tubes 40 in the
header plate 30, a sealant 70 is applied over the exposed surface
of the header plate 30 and the tubes 40. In an exemplary embodiment
of the invention, the sealant 70 may be a liquid adhesive, such as
liquid Vulkem.RTM., which is a self-leveling sealant, or other
suitable adhesive.
Sealing the surface of the header 30 serves to prevent water and
air leakage between the wet, scavenger first air stream 9 flowing
through the tubes 40 and also serves to hold the tubes 40 flush
with the top surface of the header 30. In an exemplary embodiment
of the invention, the tubes 40 are kept flush with the surface of
the header 30 to allow the water sprayed from the water
distribution manifold 8 to flow into the tubes 40 without
obstruction.
Because the tubes 40 are held approximately flush with the top
surface of the header 30, the sealant 70 may be applied by rolling
the sealant 70 onto the surface of the header plate 30, such as
with a common paint roller. By applying the sealant 70 using such a
method, the time needed to seal the tubes 40 to the header 30 is
significantly reduced. For example, applying the sealant 70 with a
roller may take approximately 5-10 minutes, or less, depending on
the size of the header plate 30. In contrast, known designs of heat
exchangers require approximately 10-20 hours to seal heat exchanger
tubes to a plate or manifold.
In another example, using a self-leveling single component liquid
urethane applied with a six inch wide roller to seal around each
tube of a header plate having approximately 44 tubes requires about
thirty seconds. In contrast, applying a known "gun grade" sealant
from a caulking gun to seal around each tube of a header plate
having approximately 44 tubes requires approximately four minutes.
The time differential between the two techniques increases as the
size of the header plate and the number of tubes increases.
Although these examples describe applying the sealant with a
roller, other methods of applying the sealant are within the scope
of this invention. For example, the sealant 70 may be sprayed on to
the surface of the header plate 30 and the tubes 40, thereby
significantly reducing the time required to seal heat exchangers
over known methods.
FIG. 6 shows a cross-section of a sealed header plate and plastic
tube, according to an exemplary embodiment of the invention. In
FIG. 6, a sealant 70, such as a water resistant paint, is applied
to the surface of the header plate 30 and the tubes 40. The sealant
70 may be applied with a roller, sprayer, or other technique. When
the sealant 70 is applied, for example applying a water resistant
paint with a roller, the sealant 70 will fill gaps which may be
present between the tubes 40 and the header plate 30.
FIG. 7 is a schematic view of a cross-section of a plastic tube,
according to an exemplary embodiment of the invention. In an
exemplary embodiment of the invention, the tubes 40 are essentially
ovoid in shape and may have an external chord length of about 3
inches and an external width of about 0.375 inches. The tubes 40
may also have a wall thickness of about 0.020 inches. A web 90 may
be formed at the center of the chord length. The web 90 is formed
transverse to the narrow, elongated portions of the tube 40 and
connects the sides of the tube 40 at the center of the cord length.
In the exemplary embodiment, the tubes 40 may range in length from
about 24 to about 96 inches, with the most common length being
about 48 inches in length. In such an exemplary embodiment, the
exchanger would have approximately 144-1000 tubes disposed therein.
Although this exemplary embodiment includes the description
discussed above, tubes 40 having other dimensions are
contemplated.
In an exemplary embodiment of the invention, the web 90 aids in
maintaining the dimensions of the tube 40 during handling and
assembly of the heat exchanger 10. For example, the web 90 aids in
maintaining the dimension of the width of the tube 40 as the tube
40 is inserted into the header 30. If the web 90 were not in place,
the tube 40 would tend to draw up on its center and result in a
tube width of less than the desired 0.375 inches of the exemplary
embodiment, thus causing problems with sealing the tube 40 to the
header 30. The result of not completely sealing the tube 40 to the
header 30 is unwanted air and water leakage between the dry supply
second air stream 11 and the wetted, humid exhaust/scavenger first
air stream 9.
In an exemplary embodiment of the invention, the tubes 40 may
include a plurality of grooves 80 formed on an inner wall surface
of the tubes 40. The grooves 80 aid in wetting the inner surface of
the tubes 40 by causing the water from the water distribution
manifold 8, through the header openings 50, to fully wet the inner
surface by capillary action. The grooves 80 also provide a greater
surface area from which water may evaporate to aid in increasing
cooling efficiency. Additionally, because the grooves 80 are formed
in the inner wall surface of the tubes 40, a thinner net wall
thickness is achieved through which energy that is to be
transferred encounters less thermal resistance to energy flow. The
grooves 80 also allow the tubes 40 to have a greater structural
rigidity, thereby preventing ballooning or collapsing of the tubes
40 as a result of fan pressure when the air intake fan 4 provides
air flow through the exchanger 10.
In an exemplary embodiment of the invention, the walls of the tube
40 are designed with a strength that allows for a determined amount
of transverse wall movement, or flex. For example, a determined
amount of transverse wall movement, i.e., on the order of 0.025
inches, occurs in the tube wall when the pressure in the tube 40 is
raised to 0.5-inches of water column pressure. As a result of such
determined transverse movement, any solid deposits, such as mineral
deposits or contaminant build-up on the inner surface of the wall,
are separated from the wall surface when the pressure changes
sufficiently to cause wall flex. For example, a sufficient pressure
change may result when the fan 4 that blows air through the heat
exchanger 10 is turned on or off. The deposits drop into a water
sump (not shown) disposed at the base 2 of the unit 1 and are
flushed from the system on a regular basis.
FIG. 8 is a flow chart showing an exemplary method of assembly of
an IEC heat exchanger according to the invention. The method of
manufacturing a heat exchanger begins in step S1000 and proceeds to
step S1010 where rigid heat exchanger tubes made, for example, of a
suitable plastic material, are formed. As noted above, in one
exemplary embodiment, the tubes have an ovoid shape. Then, in step
S1020, a rigid heat exchanger header is formed which has a
relatively flat surface containing openings. Next, in step S1030,
each opening is provided with a flange to accommodate a rigid heat
exchange tube snugly. Next, in step S1040, one or more grooves are
provided in the flange. Then, in step S1050, an heat exchange tube
is interference fit into each header opening. Next, in step S1060,
the edge of each heat exchange tube is made flush with the exterior
surface of the heat exchange header. Then, a sealant is applied to
the header with inserted heat exchange tubes. Then, the process
ends in step S1080. As noted above, a sealant may be applied using
a paint roller and/or a paint sprayer, to reduce the manufacturing
time of the IEC heat exchanger.
FIGS. 9A-9C show an exemplary embodiment of a tube having an angled
bottom portion. In an exemplary embodiment of the invention, the
tubes 40 are angled at a bottom end portion so that the tubes 40
may be more easily inserted into the openings 50 of a lower header
plate 100 and intermediate spacer plates (not shown). The tubes 40
may be angled both longitudinally and transversely at a cut on the
bottom end portion of the tubes 40. By having a compound angle cut
on a bottom end of the tubes 40, the tubes 40 may be more easily
aligned with openings in the lower header 100 having an opening in
its surface that has a perimeter shape of the same dimension as the
tubes 40. The compound angle cut allows the tubes 40 to be guided
to the openings in the lower header 100 and then press-fit into the
lower header 100. The tubes 40 may be cut during or after
manufacture of the tubes. In an exemplary embodiment, the tube 40
has an angle that is approximately 20-30 degrees from the
horizontal. Tubes having cuts forming other angle measurements are
also contemplated by this invention.
While the invention has been described in conjunction with
exemplary embodiments, these embodiments should be viewed as
illustrative, not limiting. Various modifications, substitutes, or
the like are possible within the spirit and scope of the invention.
For example, the invention may be used with or without direct
evaporative coolers.
* * * * *
References