U.S. patent application number 14/910417 was filed with the patent office on 2016-06-30 for heat transfer plate.
This patent application is currently assigned to ALFA LAVAL CORPORATE AB. The applicant listed for this patent is ALFA LAVAL CORPORATE AB. Invention is credited to Ralf BLOMGREN.
Application Number | 20160187076 14/910417 |
Document ID | / |
Family ID | 48949084 |
Filed Date | 2016-06-30 |
United States Patent
Application |
20160187076 |
Kind Code |
A1 |
BLOMGREN; Ralf |
June 30, 2016 |
HEAT TRANSFER PLATE
Abstract
A heat transfer plate comprising a number of rows of alternating
ridges and grooves, where a transition between each ridge and the
adjacent groove in the same row is formed by a portion of the heat
transfer plate that is inclined relative the central plane, and a
central opening that is configured to receive a fluid separation
device, such that a first part of the central opening may act as a
fluid inlet and a second part of the central opening may act as a
fluid outlet, wherein the plate comprises plate portions that
extend between the rows of ridges and grooves such that the rows
are separated from each other.
Inventors: |
BLOMGREN; Ralf; (Falsterbo,
SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ALFA LAVAL CORPORATE AB |
Lund |
|
SE |
|
|
Assignee: |
ALFA LAVAL CORPORATE AB
Lund,
SE
|
Family ID: |
48949084 |
Appl. No.: |
14/910417 |
Filed: |
May 27, 2014 |
PCT Filed: |
May 27, 2014 |
PCT NO: |
PCT/EP2014/060967 |
371 Date: |
February 5, 2016 |
Current U.S.
Class: |
165/80.1 |
Current CPC
Class: |
F28D 9/0056 20130101;
F28F 2225/04 20130101; F28D 9/0012 20130101; F28F 3/10 20130101;
F28F 2009/222 20130101; F28F 3/086 20130101; F28F 9/22 20130101;
F28F 9/007 20130101; F28D 9/0037 20130101 |
International
Class: |
F28F 9/007 20060101
F28F009/007; F28F 9/22 20060101 F28F009/22; F28F 3/10 20060101
F28F003/10; F28D 9/00 20060101 F28D009/00; F28F 3/08 20060101
F28F003/08 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 12, 2013 |
EP |
13180151.6 |
Claims
1. A heat transfer plate configured to be arranged in a plate heat
exchanger, the heat transfer plate comprising a number of rows
where each row has alternating ridges and grooves that extend along
a central plane of the heat transfer plate, between a top plane and
a bottom plane of the heat transfer plate, the top plane and bottom
plane being substantially parallel to the central plane and located
on a respective side of the central planed, where a transition
between each ridge and adjacent groove in the same row is formed by
a portion of the heat transfer plate that is inclined relative the
central plane, and a central opening that is configured to receive
a fluid separation device, such that a first part of the central
opening may act as a fluid inlet and a second part of the central
opening may act as a fluid outlet, characterized by plate portions
that extend along the central plane of the heat transfer plate,
between the rows of ridges and grooves such that the rows are
separated from each other.
2. A heat transfer plate according to claim 1, wherein a contact
area of a top surface of a number of the ridges, on a top side of
the heat transfer plate, is larger than a contact area of a bottom
surface of a number of the grooves, on a bottom side of the heat
transfer plate.
3. A heat transfer plate according to claim 1, wherein a number of
the rows of alternating ridges and grooves extend in a tangential
direction of the heat transfer plate.
4. A heat transfer plate according to claim 1, wherein a number of
the rows of alternating ridges and grooves extend in a radial
direction of the heat transfer plate.
5. A heat transfer plate according to claim 1, comprising a number
of sections of rows of alternating ridges and grooves, wherein an
inner section of the sections provides a higher flow resistance
than an outer section of the sections, the inner section being
arranged closer to the central opening than the outer section.
6. A heat transfer plate according to claim 5, wherein the inner
section has a higher tangential flow resistance than the outer
section.
7. A heat transfer plate according to claim 5, comprising a first,
geometrical center axis that extends across the first part of the
central opening, through a center of the heat transfer plate and
across the second part of the central opening, and a second,
geometrical center axis that is perpendicular to the first center
axis and extends through the center, wherein the inner section is,
as seen along a direction parallel to the second center axis,
arranged closer to the central opening than the outer section.
8. A heat transfer plate according to claim 5, wherein the rows of
alternating ridges and grooves of the inner section have a
different pitch than the rows of alternating ridges and grooves of
the outer section.
9. A heat transfer plate according to claim 5, wherein any of the
inner section and the outer section has the shape of a bent
rectangle.
10. A heat transfer plate according to claim 1, comprising a first
baffle and a second baffle that are arranged on a respective side
of the first part of the central opening, and a third baffle and a
fourth baffle that are arranged on a respective side of the second
part of the central opening, wherein each of the baffles has an
extension in a radial direction of the heat transfer plate.
11. A heat transfer plate according to claim 1, comprising a
peripheral edge with a first part that may act as a fluid inlet and
a second part that may act as a fluid outlet, wherein sections of
the peripheral edge that are located intermediate the first part
and the second part of the peripheral edge are configured to be
sealed with corresponding sections of a similar heat transfer plate
that is located at a top side of the heat transfer plate, and
sections of the central opening that are located intermediate the
first part and the second part of the central opening are
configured to be sealed with corresponding sections of a similar
heat transfer plate that is located at a bottom side of the heat
transfer plate.
12. A heat exchanger comprising a number of heat transfer plates
according to claim 1, a casing that forms a sealed enclosure, and a
separation device arranged in central openings of the heat transfer
plates, such that the central openings may act both as a fluid
inlet and a fluid outlet, wherein the heat transfer plates are
permanently joined and arranged in the sealed enclosure such that
alternating first and second flow paths for a first and a second
fluid are formed in between the heat transfer plates.
13. A heat exchanger according to claim 12, wherein the distance
between the central planes of at least two adjacent heat transfer
plates is smaller at inner sections of the heat transfer plates
than at outer sections of the heat transfer plates, the inner
sections being arranged closer to the central opening than the
outer sections.
14. A heat exchanger according to claim 12, wherein the heat
transfer plate comprises a central edge that is folded towards and
joined with a corresponding folded, central edge of an adjacent
heat transfer plate, and a peripheral edge that is folded towards
and joined with a corresponding folded, peripheral edge of another,
adjacent heat transfer plate.
15. A method of operating a heat exchanger according to claim 12,
wherein a first fluid enters the first fluid path via a first part
of the central opening, flows over the heat transfer plates while
making a 180.degree. turn, and exits the first fluid path via a
second part of the central opening, the first fluid thereby having
a flow direction when exiting the first fluid path that is opposite
the flow direction it had when entering the first fluid path, a
second fluid enters the second fluid path via a first part of a
peripheral edge that acts as a fluid inlet, flows over the heat
transfer plates, and exits the second fluid path via a second part
of the peripheral edge.
16. A method according to claim 15, wherein the first fluid makes a
180.degree. turn only, and the second fluid flows directly from the
first part to the second part of the peripheral edge.
17. A method according to claim 15, wherein fluid is passed through
the central opening and into the first fluid path at a pressure
that is lower than a pressure of a fluid that is passed into the
second fluid path.
Description
TECHNICAL FIELD
[0001] The invention relates to a heat transfer plate of a type
that has a central opening for receiving a fluid separation device
that allows a first part of the central opening to act as a fluid
inlet and a second part of the central opening to act as a fluid
outlet.
BACKGROUND ART
[0002] Today many different types of plate heat exchangers exist
and are employed in various applications depending on their type.
Some types of plate heat exchangers are assembled from a casing
that forms a sealed enclosure in which heat transfer plates that
are joined are arranged. The heat transfer plates form a stack of
heat transfer plates where alternating first and second flow paths
for a first and a second fluid are formed in between the heat
transfer plates.
[0003] For one type of plate heat exchangers, the so called
central-port plate heat exchanger, each heat transfer plate has a
central opening (central port) for the first fluid path. Fluid in
the first fluid path enters a heat transfer plate at an inlet
section of the central opening in the heat transfer plate, flows
across the plate and leaves the plate at an outlet section of the
same central opening. The outlet section is opposite the inlet
section and a fluid separation device is inserted in the central
opening for separating the fluid flow to the inlet section from the
fluid flow from the outlet section. Thus, the same port is, by
virtue of the separation device, used both as a fluid inlet and a
fluid outlet for a fluid that flows over the heat transfer plate.
Basically, the first fluid makes a 180.degree. turn over the heat
transfer plate, such that the first fluid leaves the plate at a
location that is, as seen across the central opening, opposite the
location where the first fluid entered the plate.
[0004] The second fluid enters the heat transfer plate at an inlet
section of a periphery of the plate, flows across the plate and
leaves the plate at an outlet section of a periphery of the plate,
which outlet section is opposite the inlet section.
[0005] Obviously, the inlet and outlet for the first fluid are
located between every second pair of plates while the inlet and
outlet for the second fluid are located between every other, second
pair of plates. Thus, the first and second fluid flows over a
respective side of a heat transfer plate, in between every second
pair of heat transfer plates. The plates of a plate pair that have
an inlet and an outlet for the first fluid are sealed to each other
along their entire peripheries while the plates of a plate pair
that have an inlet and outlet for the second fluid are sealed to
each other at their central openings.
[0006] Since the heat transfer plates are surrounded by the casing,
the central-port plate heat exchanger may withstand high pressure
levels in comparison with many other types of plate heat
exchangers. Still, the central-port plate heat exchanger is
compact, it has good heat transfer properties and may withstand
hard operation conditions without breaking.
[0007] The joined heat transfer plates are sometimes referred to as
a plate pack or a stack of heat transfer plates. The stack of heat
transfer plates has a substantially cylindrical shape with an
internal, central through hole that is characteristic for the
central-port plate heat exchanger. The stack of heat transfer
plates may be all-welded such that rubber gaskets may be omitted
between heat transfer plates. This makes the central-port plate
heat exchanger suitable for operation with a wide range of
aggressive fluids, at high temperatures and at high pressures.
[0008] During maintenance of the central-port plate heat exchanger,
the stack of heat transfer plates may be accessed and cleaned by
removing e.g. a top or bottom cover of the shell and by flushing
the stack of heat transfer plates with a detergent. It is also
possible to replace the stack of heat transfer plates with a new
stack that may be identical to or different from the previous stack
as long as it is capable of being properly arranged within the
shell.
[0009] Generally, the central-port plate heat exchanger is suitable
not only for use as a conventional heat exchanger but also as a
condenser or reboiler. In the two latter cases the shell may
comprise additional inlets/outlets for a condensate, which may
eliminate the need for a special separator unit.
[0010] The design of the central-port plate heat exchanger with its
stack of heat transfer plates provides, as indicated, a combination
of advantages and properties that are quite specific for the type.
A number of embodiments of central-port plate heat exchangers have
been disclosed, such as those found in patent document EP2002193A1.
In comparison to several other types of plate heat exchangers, the
central-port plate heat exchanger has a compact design and may
withstand high pressure levels. However, it is estimated that the
central-port plate heat exchanger may be improved in respect of its
capability to efficiently transfer heat from one of the fluids to
the other fluid, while still assuring that relatively high
pressures levels may be handled.
SUMMARY
[0011] It is an object of the invention to provide improved
performance for a central-port plate heat exchanger. In particular,
it is an object to improve the heat transfer capability of heat
transfer plates that have a respective central opening that allows
the plates to be used in a central-port plate heat exchanger.
[0012] To solve these objects a heat transfer plate is provided.
The heat transfer plate is configured to be arranged in a plate
heat exchanger and comprises a number of rows where each row has
alternating ridges and grooves that extend along a central plane of
the heat transfer plate, between a top plane and a bottom plane of
the heat transfer plate, the top plane and bottom plane being
substantially parallel to the central plane and located on a
respective side of the central plane. A transition between each
ridge and adjacent groove in the same row is formed by a portion of
the heat transfer plate that is inclined relative the central
plane. The heat transfer plates also has a central opening that is
configured to receive a fluid separation device, such that a first
part of the central opening may act as a fluid inlet and a second
part of the central opening may act as a fluid outlet, and plate
portions that extend along the central plane of the heat transfer
plate, between the rows of ridges and grooves such that the rows
are separated from each other.
[0013] The heat transfer plate is advantageous in that it is very
rigid and robust while at the same time is suitable for a
central-port plate heat exchanger and provides efficient transfer
of heat.
[0014] The plate portions that extend along the central plane of
the heat transfer plate, between the rows of ridges and grooves,
may be referred to as reinforcement sections or reinforcement
portions. The reinforcement sections have, in a direction parallel
to the central plane, typically a higher stiffness than the rows of
ridges and grooves. One or more of the reinforcement sections may,
in any combination, be any of flat, stepped and wave shaped. The
reinforcement sections may be elongated. The reinforcement sections
typically extend along the central plane of the heat transfer
plate. The reinforcement sections may extend between a first plane
and a second plane of the heat transfer plate, where the first
plane and second plane are substantially parallel to the central
plane and located on a respective side of the central plane. The
first plane is located between the top plane and the central plane.
The second plane is located between the central plane and the
bottom plane. This makes the heat transfer plate robust in its
planar extension.
[0015] A contact area of a top surface of a number of the ridges,
on a top side of the heat transfer plate, may be larger than a
contact area of a bottom surface of a number of the grooves, on a
bottom side of the heat transfer plate. This is advantageous in
that the heat transfer plate may better handle situations where the
pressure on one side of the heat transfer plate is higher than on
the other side of the heat transfer plate.
[0016] A number of the rows of alternating ridges and grooves may
extend in a tangential direction of the heat transfer plate.
[0017] A number of the rows of alternating ridges and grooves may
extend in a radial direction of the heat transfer plate.
[0018] The radial direction may be any direction that starts from a
center of the plate and is directed to a periphery of the plate.
The tangential direction may be a direction that is perpendicular
to the radial direction.
[0019] The heat transfer plate may comprise a number of sections of
rows of alternating ridges and grooves, wherein an inner section of
the sections provides a higher flow resistance than an outer
section of the sections, the inner section being arranged closer to
the central opening than the outer section. The inner section with
the higher flow resistance may be a section over which water is
intended to flow during operation of a heat exchanger in which the
heat transfer plate is arranged.
[0020] In the context herein, when a section of the heat transfer
plate has the higher flow resistance this means that the section
provides the higher flow resistance for a fluid that flows across
the section or in a channel that is at least partially formed or
enclosed by the section.
[0021] The inner section may have a higher tangential flow
resistance than the outer section.
[0022] The heat transfer plate may comprise a first, geometrical
center axis that extends across the first part of the central
opening, through a center of the heat transfer plate and across the
second part of the central opening, and a second, geometrical
center axis that is perpendicular to the first center axis and
extends through the center, wherein the inner section is, as seen
along a direction parallel to the second center axis, arranged
closer to the central opening than the outer section. The heat
transfer plate may be symmetrical about the first center axis. The
heat transfer plate may also be symmetrical about the second center
axis.
[0023] The rows of alternating ridges and grooves of the inner
section may have a different pitch than the rows of alternating
ridges and grooves of the outer section. For example, the pitch may
be different between the ridges and grooves in the same row, the
pitch may be different between the ridges and grooves in different
rows, and the pitch (distance) between different rows may be
different.
[0024] Any of the inner section and the outer section may have the
shape of a bent rectangle.
[0025] The heat transfer plate may comprise a first baffle and a
second baffle that are arranged on a respective side of the first
part of the central opening, and a third baffle and a fourth baffle
that are arranged on a respective side of the second part of the
central opening, wherein each of the baffles has an extension in a
radial direction of the heat transfer plate.
[0026] The heat transfer plate may comprise a peripheral edge with
a first part that may act as a fluid inlet and a second part that
may act as a fluid outlet, wherein sections of the peripheral edge
that are located intermediate the first part and the second part of
the peripheral edge are configured to be sealed with corresponding
sections of a similar heat transfer plate that is located at a top
side of the heat transfer plate, and sections of the central
opening that are located intermediate the first part and the second
part of the central opening are configured to be sealed with
corresponding sections of a similar heat transfer plate that is
located at a bottom side of the heat transfer plate.
[0027] According to another aspect a heat exchanger is provided,
which comprises a number of heat transfer plates of which each
incorporate of the previously described features, a casing that
forms a sealed enclosure, and a separation device that is arranged
in central openings of the heat transfer plates, such that the
central openings may act both as a fluid inlet and a fluid outlet.
The heat transfer plates are permanently joined and are arranged in
the sealed enclosure such that alternating first and second flow
paths for a first and a second fluid are formed in between the heat
transfer plates. The provided heat exchanger is typically a
central-port plate heat exchanger.
[0028] The distance between the central planes of at least two
adjacent heat transfer plates may be smaller at inner sections of
the heat transfer plates than at outer sections of the heat
transfer plates, the inner sections being arranged closer to the
central opening than the outer sections.
[0029] The heat transfer plate may comprise a central edge that is
folded towards and joined with a corresponding folded, central edge
of an adjacent heat transfer plate, and a peripheral edge that is
folded towards and joined with a corresponding folded, peripheral
edge of another, adjacent heat transfer plate.
[0030] According to another aspect a method of operating the heat
exchanger described above is provided, wherein water is passed over
sides of the heat transfer plates where baffles are arranged.
Additionally or alternatively, liquid media is passed through the
central opening and into the first fluid path while gaseous media
is passed into the second fluid path. The liquid media may be
water.
[0031] Still other objectives, features, aspects and advantages of
the invention will appear from the following detailed description
as well as from the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Embodiments of the invention will now be described, by way
of example, with reference to the accompanying schematic drawings,
in which
[0033] FIG. 1 is a cross-sectional top view of a central-port plate
heat exchanger, as seen along line B-B in FIG. 2,
[0034] FIG. 2 is a cross-sectional side view of the heat exchanger
of FIG. 1, as seen along line A-A in FIG. 1,
[0035] FIG. 3 is a cross-sectional side view of a flow divider that
is installed in the heat exchanger of FIG. 1,
[0036] FIG. 4 is a side view of the flow divider of FIG. 3,
[0037] FIG. 5 is a principal top view of a heat transfer plate that
may be installed in a heat exchanger like the one in FIG. 1,
[0038] FIG. 6 is an enlarged view of section D in FIG. 5,
[0039] FIG. 7 is a cross-sectional side view as seen along line C-C
in FIG. 6, when the heat transfer plate is arranged on top of a
similar heat transfer plate,
[0040] FIG. 8 is a principal cross-sectional side view of four heat
transfer plate of the kind shown in FIG. 5,
[0041] FIG. 9 is a top view of a section of another heat transfer
plate that may be installed in the heat transfer plate of FIG.
1,
[0042] FIG. 10 is top a view of the heat transfer plate shown in
FIG. 9, showing all of the plate,
[0043] FIG. 11 is an enlarged sectional view that corresponds to
FIG. 6, but showing another embodiment of a heat transfer
plate,
[0044] FIG. 12 is a cross-sectional side view as seen along line
E-E in FIG. 11, when the heat transfer plate is arranged on top of
a similar heat transfer plate,
[0045] FIG. 13 is a principal section of another embodiment of a
heat transfer plate,
[0046] FIGS. 14 and 15 are cross-sectional side views as seen along
lines F-F and G-G in FIG. 13
[0047] FIG. 16 is a principal section of another embodiment of a
heat transfer plate, and
[0048] FIGS. 17 and 18 are cross-sectional side views as seen along
lines H-H and I-I in FIG. 16.
DETAILED DESCRIPTION
[0049] With reference to FIGS. 1 and 2 a central-port plate heat
exchanger 2 is illustrated. The heat exchanger 2 has a casing 19
that comprises a cylindrical shell 3, a top cover 4 and a bottom
cover 5. The top cover 4 has the shape of a circular disc and a
periphery of the top cover 4 is attached to an upper edge of the
cylindrical shell 3. The bottom cover 5 has the shape a circular
disc and a periphery of the bottom cover 5 is attached to a lower
edge of the cylindrical shell 3. The covers 4, 5 are in the
illustrated embodiment welded to the cylindrical shell 3. In
another embodiment the covers 4, 5 are attached to the cylindrical
shell 3 via bolts that engage flanges (not shown) of the
cylindrical shell 3 and the covers 4, 5.
[0050] The top cover 4 has a fluid inlet 8 for a first fluid that
passes through the heat exchanger 2 via a first flow path F1. This
fluid inlet 8 is referred to as a first fluid inlet 8. The bottom
cover 5 has a fluid outlet 9 for the first fluid that passes
through the heat exchanger 2 via the first flow path F1. This fluid
outlet 9 is referred to as a first fluid outlet 9. The first fluid
inlet 8 is located at a center of the top cover 4 and the first
fluid outlet 9 is located at a center of the bottom cover 5. Thus,
the first fluid inlet 8 and the first fluid outlet 9 are located
opposite each other in the casing 19.
[0051] The cylindrical shell 3 has a fluid inlet 6 for a second
fluid that passes through the heat exchanger 2 via a second flow
path F2. This fluid inlet 6 is referred to as a second fluid inlet
6. The cylindrical shell 3 also has a fluid outlet 7 for the second
fluid that passes through the heat exchanger 2 via the second flow
path F2. The outlet 7 is referred to as a second fluid outlet 7.
The second fluid inlet 6 is located on a side of the cylindrical
shell 3, midway between the upper edge of the cylindrical shell 3
and the lower edge of the cylindrical shell 3. The second fluid
outlet 7 is located on a side of the cylindrical shell 3 that is
opposite the second fluid inlet 6, midway between the upper edge of
the cylindrical shell 3 and the lower edge of the cylindrical shell
3.
[0052] The casing 19, i.e. in the illustrated embodiment the
cylindrical shell 3, the top cover 4 and the bottom cover 5, forms
a sealed enclosure or an interior space in which a stack of heat
transfer plates 20 is arranged. The heat transfer plates in the
stack 20, such as heat transfer plates 21', 21 and 21'', are
permanently joined and arranged in the sealed enclosure such that
the first and second flow paths F1, F2 flow in respective,
alternating flow paths in between the heat transfer plates. Each of
the heat transfer plates in the stack 20 has a central opening 22.
The central openings of several heat transfer plates in the stack
20 together form a central space in the stack 20.
[0053] With further reference to FIGS. 3 and 4, a fluid separation
device 10 is inserted into the central space in the stack 20. The
separation device 10 has the form of a cylinder 12 that fits close
to central openings 22 of the heat transfer plates 21', 21, 21'' in
the stack 20. The height of the separation device 10 is the same as
the height of the central space in the stack 20. A flow divider 11
extends diagonally from an upper part of the cylinder 12 to a lower
part of the cylinder 12 and separates the interior of the cylinder
12 into a first cylinder section 15 and a second cylinder section
16. The flow divider 11 completely separates the first cylinder
section 15 from second cylinder section 16, such that no fluid may
flow directly between the sections 15, 16. Instead, fluid may flow
from the first cylinder section 15 to the second cylinder section
16 only via the heat transfer plates in the stack 20.
[0054] The separation device 10 has a first opening 13 in the first
cylinder section 15 and a second opening 14 in the second cylinder
section 16. The first opening 13 is arranged opposite the second
opening 14 with the flow divider 11 symmetrically arranged between
the openings 13, 14.
[0055] With reference to FIGS. 5-7 a heat transfer plate 21 that
may be used for the heat exchanger 2 of FIG. 1 is shown. The heat
transfer plate 21 has a number of rows 23, 24 where each row 23, 24
comprises alternating ridges and grooves, such as ridge 26 and
groove 27 of row 23 and ridge 26' and groove 27' of row 24. The
rows 23, 24 extend along a central plane P1 of heat transfer plate
21, between a top plane P2 and a bottom plane P3 of the heat
transfer plate 21. The central plane P1 is typically a plane that
extends in the center of the heat transfer plate 21, in the
illustrated embodiment at equal distances from a top side of the
heat transfer plate and a bottom side of the heat transfer plate
21. The top plane P2 and bottom plane P3 are substantially parallel
to the central plane P1 and are located on a respective side of the
central plane P1. A transition between each ridge 26 and adjacent
groove 27 in the same row 23 is formed by a portion 28 of the heat
transfer plate 21 that is inclined relative the central plane P1.
The row 24 has a corresponding inclined portion 28' between ridge
26' and groove 27'. Flat elongated plate portions 30, 31 extend
along the central plane P1 of the heat transfer plate, between the
rows 23, 24 of ridges and grooves. The rows 23, 24 are thereby
separated from each other. The flat elongated plate portions 30, 31
may be referred to as reinforcement sections. Generally, the
central plane P1 is located in, or extends along, the center of the
flat elongated plate portions 30, 31. The planes P1, P2 and P3 are
seen from the side in FIG. 7.
[0056] The ridges 26 have respective top surface 35 on the top side
38 of the heat transfer plate 21 and the grooves 27 have a
respective bottom surface 36 on the bottom side 39 of the heat
transfer plate 21. The top side 38 may be referred to as a first
side 38 of the heat transfer plate 21 and the bottom side 39 may be
referred to as a second side 39 of the heat transfer plate 21. The
top surface 35 has a contact area that abuts a heat transfer plate
that is arranged above (on the top side 38 of) the heat transfer
plate 21. The bottom surface 36 has a contact area that abuts a
heat transfer plate that is arranged below (on the bottom side 39
of) the heat transfer plate 21. For several, most or even all of
the ridges and grooves the contact area of the top surface 35 is
larger than the contact area of the bottom surface 36.
[0057] With further reference to FIG. 8 a principal view of the
heat transfer plates 21', 21, 22'' are shown together with a
further heat transfer plate 22m, along a cross section that extends
from a center C of the heat transfer plate 21 to a peripheral edge
(periphery) 29 of the heat transfer plate 21. The periphery 29 of
the heat transfer plate 21 is along its full length joined with a
corresponding periphery of the upper heat transfer plate 21'. The
plates 21', 22'' have central planes P1', P1'' that correspond to
the central plane P1 of plate 21.
[0058] The heat transfer plate 21 is partly joined with the upper
heat transfer plate 21' at the central opening 22 of the heat
transfer plate 21, i.e. the central opening 22 of the heat transfer
plate 21 is partly joined with a similar central opening of the
upper heat transfer plate 21'. The central opening 22 of the heat
transfer plate 21 is joined with the upper heat transfer plate 21'
except for a first part (section) 32 and a second part (section)
33. The parts 32, 33 of the central openings that are not joined
are defined by a respective angle .alpha. (the angle .alpha. is
shown only for the second part 33). The parts 32, 33 are arranged
symmetrically opposite each other.
[0059] The exemplified heat transfer plate 21 has a central opening
22 with a radius R2 and since the first part 32 subtends an angle
of .alpha..degree., the length L of the first part 32 is
L=.alpha..pi.R2/180. Since the second part 33 also subtend an angle
of .alpha..degree. the length L of the second part 33 is L=air
R2/180. This means that the heat transfer plate 21 is joined with
the upper heat transfer plate 21' at its central opening 22 at two
sections between the first part 32 and the second part 33. The
total length L1 of the joined sections is then the circumference of
the heat transfer plate 21 subtracted by the lengths of the parts
32 and 33, i.e. L1=2.pi.R2-2(.alpha..pi.R2/180).
[0060] The first part 32 of the central opening 22 is referred to
as a first plate inlet 32, since it acts as an inlet for a fluid
that shall flow over the heat transfer plate 21, between heat
transfer plate 21 and the upper heat transfer plate 21'. The second
part of the 33 central opening 22 is referred to as a first plate
outlet 33, since it acts as an outlet for fluid that has flown over
the heat transfer plate 21. The space between the heat transfer
plates 21 and 21' is a part of the first flow path F1.
[0061] In one embodiment it is not required to join heat transfer
plates 21 and 21' at all along their central openings. Instead the
separation device 10 prevents a flow of liquid over other sections
than the first plate inlet 32 and the first plate outlet 33. The
first opening 13 of the separation device 10 then subtends the
angle of .alpha..degree. and the second opening 14 subtend a
corresponding angle .alpha..degree..
[0062] The central opening 22 of the heat transfer plate 21 is
along its full length joined with a corresponding central opening
of the lower heat transfer plate 21''.
[0063] The heat transfer plate 21 is also partly joined with the
lower heat transfer plate 21'' at the periphery 29 of the heat
transfer plate 21, i.e. the periphery 29 of the heat transfer plate
21 is partly joined with a similar central periphery of the lower
heat transfer plate 21''. A first part (section) 17 and a second
part (section) 18 of the periphery 29 are not joined with the lower
heat transfer plate 21''. The parts 17, 18 that are not joined are
defined by a respective angle of .beta. degrees (the angle .beta.
is shown only for the first part 17). The parts 17, 18 are
symmetrical and are arranged opposite each other.
[0064] Since the exemplified heat transfer plate 21 has a circular
shape with a radius R1 and since the first part 17 subtends an
angle of .beta..degree., the length L of the first part 17 is
L=.beta..pi.R1/180. Since the second part 18 also subtend an angle
of .beta..degree. the length L of the second part 18 is
L=.beta..pi.R1/180. This means that the heat transfer plate 21 is
joined with the lower heat transfer plate 21'' at its periphery 29
at two sections between the first part 17 and the second part 18.
The total length L2 of the joined sections is then the
circumference of the heat transfer plate 21 subtracted by the
lengths of the parts 17 and 18, i.e.
L2=2.pi.R1-2(.beta..pi.R1/180).
[0065] The first part 17 of the periphery 29 is referred to a
second plate inlet 17, since it acts as an inlet for a fluid that
shall flow under the heat transfer plate 21, between heat transfer
plate 21 and the lower heat transfer plate 21''. The second part 18
of the central opening 22 is referred to a second plate outlet 18,
since it acts as an outlet for fluid that has flown under the heat
transfer plate 21. The space between the heat transfer plates 21
and 21'' is a part of the second flow path F2.
[0066] In one embodiment it is not required to join heat transfer
plates 21, 21'' at all along their peripheries. Instead the
cylindrical shell 3 seals the plates at their peripheries to
prevent a flow of liquid over all sections but for the second plate
inlet 17 and the second plate outlet 18. Thus, the cylindrical
shell 3 then seals the peripheral edges apart from at the sections
17, 18 subtended by a respective angle .beta..degree..
[0067] The joining of the heat transfer plates 21''', 21', 21, 21''
is typically accomplished by welding. The heat transfer plate 21
may have a central edge 92 that is folded towards and joined with a
corresponding folded, central edge 92'' of adjacent heat transfer
plate 21''. The heat transfer plate 21 may also have a peripheral
edge 91 that is folded towards and joined with a corresponding
folded, peripheral edge 91' of the other adjacent heat transfer
plate 21'.
[0068] The heat transfer plates may then be joined at to each other
at their folded edges. A seal may be arranged between the
separation device 10 and the heat transfer plates for sealing
plates like plates 21 and 21' along their central openings 22 at
all sections but at the first plate inlet 32 and the first plate
outlet 33. A seal may also be arranged between the cylindrical
shell 3 and the heat transfer plates for sealing plates like plates
21 and 21'' along their peripheries 29 at all sections but at the
second plate inlet 17 and second plate outlet 18.
[0069] Turning back to FIGS. 1-4 the flow over the heat transfer
plates may be seen. The flow of the first fluid follows the first
flow path F1. By virtue of the separation device 10 and its flow
divider 11, the flow of the first fluid passes the first fluid
inlet 8, enters the first cylinder section 15 and flows out through
the first opening 13 in the separation device 10, into first plate
inlets 32 of the heat transfer plates 21 in the stack 20. The first
fluid then "turns around" when it flow across the heat transfer
plates, see the first flow path F1 in FIG. 1, leaves the heat
transfer plates via first plate outlets 33 of the heat transfer
plates 21 in the stack 20 and enters the second cylinder section 16
via the second opening 14. From the second cylinder section 16 the
first fluid flows to the first fluid outlet 9 where it leaves the
heat exchanger 2.
[0070] The flow of the second fluid follows the second flow path
F2. The flow of the second fluid passes the second fluid inlet 6
and into second plate inlets 17 of the heat transfer plates 21 in
the stack 20. For facilitating distribution of the fluid into all
second plate inlets 17 of the heat transfer plates, the heat
exchanger 2 may at the second fluid inlet 6 comprise a distributor
(not shown). A collector (not shown) that has a similar shape as
the distributor may be arranged at the second fluid outlet 7.
Alternatively, the heat transfer plates 21 may comprise a first
cut-out 46 at the second plate inlet 17 and a second cut-out 47 at
the second plate outlet 18 (see FIG. 1). Even though such cut-outs
46, 47 give the periphery 29 of the heat transfer plate 21 a
different shape, the second plate inlet 17 and the second plate
outlet 18 may still subtend a respective angle of
.beta..degree..
[0071] When the second fluid has entered the second plate inlets 17
it flows across the plates in the stack 20, see the second flow
path F2 in FIG. 1, leaves the heat transfer plates in the stack 20
via the second plate outlets 18 and thereafter leaves the heat
exchanger 2 via the second fluid outlet 7.
[0072] With reference to FIGS. 9 and 10 another embodiment of a
heat transfer plate 121 is illustrated. The heat transfer plate 121
is symmetrical about first geometrical axis A1 and second
geometrical axis A2. The heat transfer plate 121 of FIGS. 9 and 10
have several features that are same as for the heat transfer plate
21 of FIG. 5. For example, the heat transfer plate 121 has a
central opening 22 with a first plate inlet 32 and a first plate
outlet 33, and a periphery 29 with a second plate inlet 48 and a
second plate outlet 49. The second plate inlet 48 and the second
plate outlet 49 comprise a respective first and second cut-out like
the cut-outs 46, 47 shown in FIG. 1. The heat transfer plate 121 is
joined and sealed to adjacent, similar plates in a manner that
corresponds to how the heat transfer plate 21 of FIG. 5 is joined
and sealed to other heat transfer plates.
[0073] The heat transfer plate 121 also has flat, elongated plate
portions 130, 131 that extend along the central plane of the heat
transfer plate 121, between the rows of ridges and grooves such
that the rows are separated from each other. The rows are arranged
different in different sections of the heat transfer plate 121.
[0074] For example, a first section 41 of the rows 42 of
alternating ridges 43 and grooves 44 extend in a tangential
direction D1. As is known, a tangential direction is a direction
that is orthogonal to the radius of rotation of the plate, as seen
from the center C of the heat transfer plate 121, which has a
radius R1. A radial direction is a direction that is parallel to
the radius of rotation of the plate, as seen from the center C of
the heat transfer plate 121.
[0075] A second section 51 of the rows 52 of alternating ridges 53
and grooves 54 also extend in a tangential direction D1 while a
third section 61 of the rows 62 of alternating ridges 63 and
grooves 64 extend in a radial direction D2. A fourth section 81 of
the rows of alternating ridges and grooves extend in a radial
direction D2.
[0076] The second section 51 has the shape of a bent rectangle. By
bent reactance is meant a geometrical shape where two sides of the
shape have the form of a respective arc where the arcs have
different radiuses but shares the same radial center and subtends
the same angle, and where the two sides are joined by to additional
sides that extends in a radial direction. A bent rectangle may be
said having the form of a truncated circular sector or annular
sector.
[0077] The second section 51 is arranged closer to the center C
than the third section 61 and may be referred to as an "inner
section". The third section 61 is arranged further from the center
C and may be referred to as an outer section or a peripheral
section. From a geometrical point of view, the first geometrical
axis A1 extends across the first part 32 of the central opening 22,
through the center C of the heat transfer plate 121 and across the
second part 33 of the central opening 22. The second geometrical
axis A2 is perpendicular to the first center axis A1 and extends
through the center C. Then the inner section 51 is, as seen along a
direction parallel to the second center axis A2, arranged closer to
the central opening 22 than the outer section 61.
[0078] The inner section 51 has a higher flow resistance than the
outer section 61. Specifically, the inner section 51 has a higher
tangential flow resistance than the outer section 61. To accomplish
different flow resistances, the rows 52 of alternating ridges and
grooves 53, 54 of the inner section 51 may, for example, have a
different pitch than the rows 62 of alternating ridges and grooves
63, 64 of the outer section 61. Another way to accomplish the
different flow resistance is to arrange the rows of ridges and
grooves in different directions. For example, a tangential
direction of the rows may give a higher tangential flow resistance
than a radial direction of the rows.
[0079] Moreover, the flow resistance may be increased by decreasing
the pitch (distance) between the rows. Increasing flow resistance
in this way is particularly efficient when the rows extend in a
flow direction, which may be the tangential direction.
[0080] The flow resistance may e.g. in the outer section 61 be
decreased by arranging the rows in a non-staggered manner, i.e. by
arranging the ridges in the different rows after each other in the
flow direction. When this is done the grooves of different rows are
arranged after each other in the flow direction or tangential
direction. Decreasing flow resistance in this way is particularly
efficient when the rows extend in a radial direction, or transverse
the flow direction.
[0081] The flow resistance of a section may also be increased by
giving the heat transfer plate 21 a shape that locates flat
elongated plate portions 30, 31 relatively closer to an adjacent
plate, which effectively decreases the flow path and thus increases
the flow resistance at the location of the section.
[0082] The heat transfer plate 121 has a first baffle 71 and a
second baffle 72 that are arranged on a respective side of the
first plate inlet 32 (first part 32) of the central opening 22, and
a third baffle 73 and a fourth baffle 74 that are arranged on a
respective side of the first plate outlet 33 (second part 33) of
the central opening 22. Each of the baffles 71, 72, 73, 74 has an
extension in a radial direction D2 of the heat transfer plate. They
may in one embodiment extend in parallel with a respective radial
direction of the heat transfer plate 121. The baffles typically
have the shape of an elongated ridge.
[0083] The baffles ensures that fluid that enters the first plate
inlet 32 and leaves the first plate outlet 33 is distributed more
evenly over the heat transfer plate 121, such that the fluid does
not take shortcuts by flowing very close to the central opening 22
when flowing from the first plate inlet 32 to the first plate
outlet 33.
[0084] In one application of the heat transfer plate 121 the heat
exchanger in which the heat transfer plate 121 is arranged is
operated by passing water over a side of the heat transfer plate
where the baffles 71, 72, 73, 74 are arranged, i.e. on the side
where the baffles form a respective protrusion or elongated
ridge.
[0085] With reference to FIGS. 11 and 12 another embodiment of a
heat transfer plate 221 is illustrated. The heat transfer plate 221
has a number of rows 223, 224 where each row 223, 224 comprises
alternating ridges and grooves. Reinforcement sections 230, 231
extend along the central plane P1 of the heat transfer plate,
between the rows 223, 224 of ridges and grooves. Each of the
reinforcement sections 230, 231 is wave shaped and extends along
the central plane P1 of the heat transfer plate, between a first
plane P4 and a second plane P5 of the heat transfer plate. The
first plane P4 and second plane P5 are substantially parallel to
the central plane P1 and located on a respective side of the
central plane P1. The first plane P4 is located between the top
plane P2 and the central plane P1. The second plane P5 is located
between the central plane P1 and the bottom plane P3. In this
context, when ridges and grooves extend between two planes P2, P3
this means that all of the ridges and grooves are located between
these planes P2, P3. In a similar manner, all of the reinforcement
sections 230, 231 extend between the first and second planes P4,
P5, i.e. the extension of the reinforcement sections 230, 231 is
limited by the first and second planes P4, P5.
[0086] With reference to FIGS. 13-15 another embodiment of a heat
transfer plate 321 is illustrated. This embodiment shows rows 323,
324 of alternating ridges and grooves that are separated by a
reinforcement section 330. The rows 323, 324 are non-staggered and
the reinforcement section 330 is stepped.
[0087] With reference to FIGS. 16-18 another embodiment of a heat
transfer plate 421 is illustrated. This embodiment shows rows 423,
424 of alternating ridges and grooves that are separated by a
reinforcement section 430. The rows 423, 424 are staggered and the
reinforcement section 430 is both stepped and tilted.
[0088] From the description above follows that, although various
embodiments of the invention have been described and shown, the
invention is not restricted thereto, but may also be embodied in
other ways within the scope of the subject-matter defined in the
following claims.
* * * * *