U.S. patent application number 13/139676 was filed with the patent office on 2012-05-17 for high pressure port peninsula.
This patent application is currently assigned to Swep International AB. Invention is credited to Sven Andersson, Tomas Dahlberg, Svante Hoberg.
Application Number | 20120118546 13/139676 |
Document ID | / |
Family ID | 41819669 |
Filed Date | 2012-05-17 |
United States Patent
Application |
20120118546 |
Kind Code |
A1 |
Andersson; Sven ; et
al. |
May 17, 2012 |
HIGH PRESSURE PORT PENINSULA
Abstract
A brazed plate heal exchanger (400) for exchanging heat between
at least two media, wherein at least one of the media could have a
working pressure of at least 50 bars, comprises a number of heat
exchanger plates (100; 200) comprising a pressed pattern of ridges
and grooves. Those are adapted to form flow channels for media to
exchange heat flowing through said flow channels. The plates (100;
200) further comprises port openings (120, 130; 220; 300, 310)
arranged to allow fluid communication with said flow channels and a
skirt (140) extending around the periphery of the heat exchanger
plates (100; 200). Skirts (140) of neighboring plates (100; 200)
are arranged to contact one another in an overlapping manner in
order to obtain a connection sealing the flow channels. At least
one of said port openings (120, 130; 220; 300, 310) is placed on a
peninsula (150) surrounded by the skirt (140) over at least 100
degrees.
Inventors: |
Andersson; Sven;
(Hassleholm, SE) ; Hoberg; Svante; (Astorp,
SE) ; Dahlberg; Tomas; (Helsingborg, SE) |
Assignee: |
Swep International AB
Landskrona
SE
|
Family ID: |
41819669 |
Appl. No.: |
13/139676 |
Filed: |
December 11, 2009 |
PCT Filed: |
December 11, 2009 |
PCT NO: |
PCT/EP2009/066928 |
371 Date: |
September 8, 2011 |
Current U.S.
Class: |
165/170 |
Current CPC
Class: |
F28F 2225/00 20130101;
F28F 3/046 20130101; F28D 9/005 20130101 |
Class at
Publication: |
165/170 |
International
Class: |
F28D 9/00 20060101
F28D009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 17, 2008 |
SE |
0802596-7 |
Claims
1. A brazed plate heat exchanger for exchanging heat between at
least two media, wherein at least one of the media could have a
working pressure of at least 50 bars, the heat exchanger comprising
a number of heat exchanger plates comprising a pressed pattern of
ridges and grooves adapted to form flow channels for media to
exchange heat flowing through said flow channels, the plates
further comprising port openings arranged to allow fluid
communication with said flow channels and a skirt extending around
the periphery of the heat exchanger plates, skirts of neighboring
plates being arranged to contact one another in an overlapping
manner in order to obtain a connection sealing the flow channels,
wherein at least one of said port openings is placed on a peninsula
surrounded by the skirt over at least 100 degrees.
2. The brazed plate heat exchanger of claim 1, wherein the skirt
surrounds the at least one port opening provided on the peninsula
over at least 120 degrees.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a heat exchanger comprising
a number of heat exchanger plates comprising a pressed pattern of
ridges and grooves adapted to form flow channels for media to
exchange heat flowing through said flow channels, the plates
further comprising at least four port openings arranged to allow
fluid communication to said flow channels and a skirt extending
around the periphery of the heat exchanger plates, said skirt
sealing the flow channels.
PRIOR ART
[0002] In the art of heat pumps, there has been a recent trend to
use carbon dioxide as the refrigerant, since carbon dioxide is
known to give excellent COP values, i.e. efficiency, in high
temperature applications. Moreover, carbon dioxide has very little
impact on the environment, compared to the refrigerants that are
commonly used today.
[0003] One problem with using carbon dioxide is that its operating
pressure is high; other commonly used coolants operate at pressures
of up to 40 bars, but carbon dioxide systems must be able to
withstand pressure of about 140 bars. This high pressure makes it
necessary to use heat exchangers able to withstand such pressures.
A relatively common type of heat exchanger for carbon dioxide
applications is the "dual pipe" exchanger, which comprises two
parallel pipes, which are interconnected to enable heat transfer
between the pipes. Usually, a pipe with a small diameter is used
for the high pressure medium, whereas a pipe with a large diameter
is used for the low pressure medium. In order to increase the heat
exchanging area, more than one small diameter pipe may be
interconnected to a pipe having a larger diameter, and there are
even designs wherein the small diameter pipes are embedded within a
pipe wall of the large diameter pipe. Dual pipe heat exchangers
have excellent properties concerning capability to withstand
pressure, but are inefficient in terms of heat exchanging
capability vs. weight.
[0004] For ordinary heat pump applications, i.e. applications
wherein a commonly used coolant is used, one common type of heat
exchanger is a Compact Brazed Exchanger (CBE). This type of heat
exchanger is efficient both in terms of cost, performance, material
requirement and space requirement, but CBE:s have up till now
exhibited a low capability of withstanding high pressure, i.e
pressures exceeding about 50 bars.
[0005] A CBE generally comprises a number of heat exchanger plates,
all of which being provided with a pressed pattern of ridges and
grooves and port openings for fluid communication with flow
channels formed by interaction between the pressed patterns of
ridges and grooves of neighboring plates. The pressed patterns of
neighboring plates are arranged such that ridges of one plate
contact grooves of a neighboring plate. During the brazing
operation, the contact points are brazed to one another to provide
sufficient strength to the flow channel formed by the patterns of
ridges and grooves of neighboring plates. The flow channels formed
by the interaction between the ridges and grooves are laterally
sealed by interacting skirts provided around the circumference of
the heat exchanger plates.
[0006] Pressure tests of CBE:s have shown that one position where
the heat exchangers are particularly prone to break is the port
openings, or rather, the heat exchanging area between the port
openings. The reason for this is rather clear; the contact point
density is low in the vicinity of the port openings, due to the
surface area of the port openings, which surface area is free of
joined contact points between the plates. Despite the lower contact
point density, the same force for an equal pressure must be
transferred through the contact points.
[0007] It is the object of the invention to provide a CBE able to
withstand a pressure high enough for allowing the heat exchanger to
be used in carbon dioxide applications.
SUMMARY OF THE INVENTION
[0008] According to the invention, this and other problems are
solved by providing at least one of the port openings on a
peninsula which extends outside the general area of a heat
exchanging surface of heat exchanger plates comprised in the heat
exchanger, said peninsula being closely surrounded by skirts over
at least 100 degrees.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Hereinafter, the invention will be described with reference
to the appended drawings, wherein:
[0010] FIG. 1 is a perspective view of a heat exchanger plate
according to a first embodiment of the present invention;
[0011] FIG. 2 is a plan view of a heat exchanger plate according to
a second embodiment of the present invention;
[0012] FIG. 3 is a perspective view of a heat exchanger plate
according to a third embodiment of the present invention;
[0013] FIG. 4 is a perspective view of a heat exchanger
manufactured from a number of heat exchanger plates according to
the third embodiment; and
[0014] FIG. 5 is a perspective view of a heat exchanger plate
according to a fourth embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
[0015] With reference to FIG. 1, a heat exchanger plate 100
comprises a heat exchanging area 110, provided with a pressed
pattern (not shown) of ridges and grooves, in a way well known to
persons skilled in the art. The patterns of ridges and grooves of
neighboring plates are adapted to provide flow channels between the
plates due to contact between ridges of one plate contacting
grooves of its neighboring plate when the plates 100 are stacked
onto one another in a way well known by persons skilled in the art.
The heat exchanger 100 also comprises at least two low pressure
port openings 120 and two high pressure openings 130. The port
openings are in selective fluid communication with the flow
channels formed by the pattern of ridges and grooves in a way to be
described below. A skirt 140 surrounds the heat exchanging area 110
and is arranged such that two skirts of neighboring plates interact
to form a seal between such neighboring plates by an overlapping
engagement between neighboring skirts, hence sealing the flow
channels formed by the pressed pattern of ridges and grooves.
[0016] As can be seen in FIG. 1, the high pressure port 130 is
placed on a "peninsula" 150 extending out from the heat exchanging
area 110. The peninsula 150 is closely surrounded by the skirt 140
over an angle .alpha. of about 180 degrees.
[0017] The angle .alpha. is more clearly defined in FIG. 2. FIG. 2
shows virtually the same embodiment as is shown in FIG. 1, with the
exception that FIG. 2 shows the skirt 140 being surrounded by a
plate portion 160 which is provided with a pressed pattern of
ridges and grooves. The ridges and grooves 165, 166, respectively,
of the plate portion 160 are adapted to contact corresponding
ridges and grooves of the plate portion 160 of a neighboring plate,
and hence increase the strength of the seal formed by the skirt
140.
[0018] FIG. 3. shows still a further embodiment of a heat exchanger
plate 200 according to the present invention. A peninsula 210
extends in a direction parallel to a length axis of the heat
exchanger plate 200, and a high pressure port 220 is located on
such peninsula. Please note that the skirt 140 closely surrounds
the high pressure port 220 over about 180 degrees.
[0019] In order to manufacture a heat exchanger from a number of
heat exchanger plates 100 or 200, a desired number of heat
exchanger plates are stacked onto one another. Not all heat
exchanger plates 100 or 200 are of the same design, every other
plate in the stack is a mirror image of its neighboring plates; by
varying the height of the areas surrounding both the high pressure
ports and the low pressure ports, it is possible to determine which
port opening that shall communicate with each flow channel. This
method of determining the fluid communication in a heat exchanger
is well known by persons skilled in the art, and will hence not be
more thoroughly discussed.
[0020] After the heat exchanger plates have been stacked in the
appropriate manner to form a heat exchanger, the entire plate
package is subjected to a brazing operation, i.e. the plate package
is put into a furnace and heated to a temperature sufficient to
melt a brazing material arranged between the plates. After the
brazing material has melted, it will concentrate to areas wherein
the plates are lying close to one another (the concentration of the
brazing material is due to capillary forces). Consequently, the
plates will be joined by a brazing connection after the heat
exchanger has cooled down sufficiently to allow the brazing
material to solidify.
[0021] Whenever an internal pressure is applied to a plate heat
exchanger, the plates are forced in opposite directions; hence, the
brazing connections between the ridges and grooves of the
neighboring plates will be subjected to a tensile stress. Since the
skirts 140 are arranged almost perpendicular to the heat exchanging
portions of the plates, the force urging the plates in opposite
directions will result in a shear stress in the brazing connections
between the skirts. However, since the force transmitting area is
significantly larger for the overlapping skirts as compared to the
contact points between the plates, the skirts will be able to
transfer a larger force than the contact points between the
plates.
[0022] In FIG. 4, a heat exchanger 400 comprising a number of heat
exchanger plates 200 is shown. It can clearly be seen that the
skirts 140 form an edge around the circumference of the heat
exchanger plates, and it is also very clear how the skirts 140
interact to form a half-pipe like closure around the high pressure
port openings 130.
[0023] The half-pipe like closure formed by the skirts 140 around
the high pressure port openings 130 gives a very high strength
around the port openings; the forces emanating from the surface
area of the port will be transferred through the connections
between the overlapping skirts.
[0024] In other words, the peninsula placement of the high pressure
port 130 increases the strength of the port by fact that a large
portion of the port opening lies in the vicinity of the skirt 140;
as previously described, skirts 140 of neighboring plates will
overlap to form a sealed connection between the plates. Around the
high pressure port opening, the overlapping skirts will form a
"half-pipe" of overlapping skirts. Such a half pipe-like array of
overlapping skirts has proven to be very strong, it can absorb
forces in a much more efficient way than e.g. the contact points
between the pressed patterns of the heat exchanging areas.
[0025] In another aspect of the present invention, not only the
high pressure port is placed on a peninsula; in FIG. 5, a heat
exchanger plate according to a further embodiment embodying this
feature of the present invention is shown. In this embodiment, both
a high pressure port 300 and a low pressure port 310 are placed on
peninsulas 320, 330, respectively, the definition of a peninsula
being that the skirts surrounding the plates closely surrounds the
port openings over more than 90 degrees.
[0026] It should be noted that many modifications are possible
within the scope of the invention, such as it has been defined in
the appended claims. One such modification is that the skirt 140
not necessarily must be arranged such that it only surrounds the
heat exchanger as a whole; it is also possible to provide any
portion of the heat exchanger plates with skirts. For example, a
skirt could be arranged such that an opening is formed in the heat
exchanger; any arrangement wherein plate portions extend in a
generally perpendicular direction vis-a-vis a plane of the heat
exchanger, and wherein such plate portions of neighboring plates
are designed to overlap corresponding plate portions of neighboring
plates in a way that has been described above with reference to the
skirt 140 are regarded as skirts in the wording of the claims.
* * * * *