U.S. patent number 3,661,203 [Application Number 04/878,607] was granted by the patent office on 1972-05-09 for plates for directing the flow of fluids.
This patent grant is currently assigned to Parkson Corporation. Invention is credited to Terry Bernard Mesher.
United States Patent |
3,661,203 |
Mesher |
May 9, 1972 |
PLATES FOR DIRECTING THE FLOW OF FLUIDS
Abstract
A plate for directing the flow of fluids which is shaped so as
to provide contact points capable of spacing it from and supporting
it against similar plates, is also provided with further contact
points so that by suitable arrangement of the plates, the spacing
therebetween can be varied. The basic contact points on the
standard plate are provided by a herring-bone pattern of V-shaped
hill and valley corrugations and, preferably, the further contact
points are formed by stamping the plate so that portions of the
hill structure of the corrugations are provided with reversed hill
and valley formations, although they may be formed by studs or
projections attached to the plate.
Inventors: |
Mesher; Terry Bernard (Kent,
EN) |
Assignee: |
Parkson Corporation (Fort
Lauderdale, FL)
|
Family
ID: |
25372383 |
Appl.
No.: |
04/878,607 |
Filed: |
November 21, 1969 |
Current U.S.
Class: |
165/167;
165/DIG.362 |
Current CPC
Class: |
F28F
3/083 (20130101); F28F 3/046 (20130101); Y10S
165/362 (20130101) |
Current International
Class: |
F28F
3/08 (20060101); F28b 003/08 () |
Field of
Search: |
;165/5,10,166MF,167,166,7 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Matteson; Frederick L.
Assistant Examiner: Streule; Theophil W.
Claims
What we claim is:
1. A plurality of heat exchanger plates arranged in stacked
relationship and defining a plurality of flow channels between the
plates, each plate comprising a sheet of material the surface of
which forms a pattern of hill and valley corrugations, each
corrugation consisting of two oppositely inclined surface portions
that intersect to form a crest line, at least every second plate
including a series of surface deformations that form abutments
disposed within the valleys of the corrugations, the plates being
arranged in pairs of two plates that are similarly oriented so that
the plates which form a pair are internested and the abutments are
utilized as contact points, each pair of plates having an
orientation opposite that of the adjacent pairs so that spaced
locations along the crest lines are utilized as contact points
between plates of different pairs to prevent internesting, whereby
flow channels of at least two different crosssectional areas are
provided.
2. The apparatus of claim 1 wherein each plate is rectangular in
shape.
3. The apparatus of claim 1 wherein the corrugations of each plate
are arranged in a herring-bone pattern.
4. The apparatus of claim 1 wherein said abutments are formed by
reversed hill and valley corrugations pressed into the plates on
which they are provided.
5. The apparatus of claim 1 wherein the corrugations are
substantially V-shaped.
Description
This invention relates to plates for directing the flow of fluids,
and, more particularly, to a new and improved plate which is
capable of being oriented in either of two relationships with
another similar plate so as to vary the cross-sectional area of the
flow channels therebetween. In a preferred embodiment of the
invention described below, the plates are employed in the
environment of a plate heat exchanger.
Plate heat exchangers are widely used for the transfer of heat from
one fluid to another, but are nevertheless subject to a number of
compromises and disadvantages in practice. It has long been
recognized that plate heat exchangers are useful because of their
compactness and versatility of operation, but the tooling equipment
required to manufacture plates is costly and therefore it is not
generally economical to manufacture more than a relatively few
different designs of plate. One of the major costs in producing a
plate heat exchanger is the development of, and stamping equipment
capitalization for, the particular plate design chosen.
Manufacturing equipment is costly and manufacturers have found it
generally uneconomical to manufacture more than one design of plate
for a given size; for example, even for the larger manufacturers,
more than three or four different sizes of plate are uncommon, if
not unknown. Consequently, each type of plate made by a
manufacturer is often used inefficiently for a wide range of
different applications. It is obviously very desirable for a single
form of plate to be used and for the desired flowpaths for the two
fluids to be created by suitably arranging the plates in the
exchanger. Because one main source of the cost of plate heat
exchangers lies in the amount of metal used, which is often
relatively expensive, the plates are generally thin, but the
thinness of the plates makes them relatively weak and so
necessitates their having a good self-supporting design. It is also
desirable, if there are appreciable heat transfer surfaces and/or
pressure drops to be provided for, for the plates to be
self-supporting against fluid pressures. This requires, in
practice, that the individual plates in a heat exchanger shall be
in contact at spaced locations over their surfaces, so as to be
self-supporting and/or to ensure that the flowpaths between them
remain generally constant when the heat exchanger is in use. These
requirements have precluded the adoption of advantageous variations
in flowpath spacing and other geometry however.
A conventional heat exchanger plate is of rectangular form, having
ports in each of the four corners of the rectangle and having its
major portion embossed, such as in a rib formation. A common
practice is to impress raised portions or a herring-bone or other
pattern of "hill-and-valley" corrugations over the entire major
area of each plate, with appropriate subsidiary hill-and-valley
corrugations leading from and to each of the ports in the corners,
a circumferential marginal region being provided for co-operating
with a gasket or other sealing member to prevent leakage between
dissimilar fluid flowpaths and/or fluid leakage to the exterior of
the plate exchanger package, so as to seal the plate relative to
the next ones in the heat exchanger. If a number of identical
plates of such a form were to be arranged with their corrugations
similarly directed, no sealing members being interposed, the plates
would nest completely and there would be substantially no spaces
between them. It is common practice, therefore, to form a plate
heat exchanger by reversing each alternate plate, so that the
impressed configuration is directed alternately in the respective
plates in the heat exchanger, for example, in a "herring-bone"
pattern. The necessary support of the plates is then given by
virtue of the points of contact where the hill formations on one
plate cross the hill formations of the adjacent plates. It will be
appreciated that what is a hill formation on one side of a plate is
a valley formation on the other. With an arrangement of this kind,
it will be seen that the plate spacing equals the size of the
hill-and-valley corrugations in the individual plates.
While it is possible to form a heat exchanger with a number of
identical plates of this kind and to obtain reasonable operating
results from it, it is almost universally true that the two fluids
which are passed through a heat exchanger are different, either
being different liquids or possibly the same fluid having different
temperatures. In any practical case therefore, a compromise is
necessarily adopted because the flowpath for one of the fluids is
clearly not so ideally suited to the other fluid. For example, if
one of the fluids has a higher viscosity than the other, it is
evident that, given equal spacing between and arrangement of the
plates in the respective flowpaths, the more viscous fluid will
require to be fed at a higher pressure. A particular example of
inefficient two-component, liquid-liquid heat exchange in a plate
heat exchanger is the cooling of a viscous oil by water. It is
self-evident that a plate spacing which is well suited to the
viscosity, thermal conductivity, temperature and pressure of the
oil is not well suited to the similar properties of the water. For
pressure drop reasons alone, the characteristic flexibility of
plate exchangers in adjusting the lengths of the flowpaths of one
of the fluids, with respect to the other, is not generally
sufficient. It is therefore highly desirable to provide for
flowpath cross-sectional area and geometry differentiation in all
heat transfer applications. It is also highly desirable to provide
for flowpath differentiation in all heat transfer applications
involving gas and liquid or vapor and liquid. If the plate spacing
can be varied and consequently the cross-sectional flow area of the
flowpaths, the pressure drop of that flowpath can be readily
controlled. This allows an improved performance to be obtained,
employing a narrow high-pressure-drop flowpath for liquids,
together with a wider low-pressure-drop flowpath for vapor or
gas.
According to the invention, a variable spacing between the
respective plates of a plate heat exchanger is achieved, the plates
otherwise being identical, by providing a secondary set of
self-supporting contact points on at least some of the plates in
the heat exchanger plate assembly, whereby respective pairs of
plates can be assembled to have a flowpath spacing which is less
than, equal to or greater than the spacing given by the primary set
of self-supporting contact points of the set of plates. In addition
to varying the plate spacing and therefore the cross-sectional area
of the flowpath, it will be appreciated that, by proper selection
of the embossed form of the primary set of plates and of the
secondary set of self-supporting contact points, the actual
geometry and therefore the thermal characteristics of the resulting
flowpath may be advantageously modified, in a wide variety of
ways.
The present invention offers for the first time a convenient and
economical means of varying the mechanical and thermal
characteristics of plate heat exchangers for some of the fluids in
process substantially independently of the others. Working fluids
are in general dissimilar in properties and so it follows that the
heat exchanger flowpaths should be correspondingly different.
Materials differing in density, viscosity, specific heat and
thermal conductivity must, for efficient heat transfer, have
different flowpath conditions.
It is well-known from conventional plate heat exchanger design that
it is generally impractical to vary the plate spacing by using a
number of different plate forms. Normally the duty is for two
working fluids, so that one plate forms the flowpath boundary for
both fluids. Each fluid flows in alternate passage-ways. Since
economic considerations preclude the manufacture and use of a
complicated spacer for varying the flowpath geometry and spacing
and because of the general necessity for the plates to be of a
self-supporting nature, for existing plate heat exchanger design,
the flowpath for one fluid cannot be varied independently of the
other. The flowpath for one fluid cannot be varied independently of
the other, since each plate forms a boundary for the two flows. The
use of a spacer to increase plate separation is uneconomical and
impractical because of the necessity for the plates to be
self-supporting.
In putting the invention into effect, one preferred way is to form
the secondary supports by a simple stamping or fabricating
operation. Their form and/or depth may be varied for finer
adjustment in flowpath conditions. In this way, a single plate
design may be simply and cheaply varied for a wide range of duties.
The primary form of plate may be designed so that relative
roughness, turbulence, hydraulic diameter and other factors may be
increased or decreased by correct selection of the secondary
support design and orientation.
Other ways in which the desired subsidiary set of contact points
can be provided is for those plates which require modification to
have secondary contact points in the form of studs, projections or
other small abutment members attached or otherwise disposed at
appropriately spaced locations on the plates. Another way in which
the subsidiary spacing can be obtained is by the interposition
between plates of a set of subsidiary contact points in the form of
sets of contact members having the form for instance of a wire
spider or other member to which stud or other contact members are
attached. The individual wires in the spacer assembly so formed may
desirably be shaped and arranged so as to follow the channels which
are defined between the hill-and-valley formations of adjacent
plates, so that the spacer members attached to the wires and not
the wires themselves govern the modified spacing between the
adjacent plates. In this embodiment, a plate heat exchanger can be
simply manufactured by appropriately arranging a plurality of
identical and unmodified plates and inserting spacer assemblies for
instance between each alternate pair of plates, so as to
appropriately enlarge, decrease or modify the flowpath spacing for
one of the two fluids. It will be appreciated that, in all cases,
the sealing member or gasket material used is varied in thickness
to suit the varied plate spacings which are present in the
assembled heat exchanger.
In order that the invention may be more readily understood, a
preferred embodiment is described below by way of illustration in
conjunction with the accompanying drawings. In the drawings:
FIG. 1 shows, in exploded perspective view, portions of the
individual plates and gasket members of a heat exchanger according
to one embodiment of the present invention;
FIG. 2 shows the assembled plates of the heat exchanger of FIG.
1;
FIG. 3 shows an end elevation of the plates of the heat exchanger
of FIGS. 1 and 2.
Referring to the drawings, a number of the plates of a plate heat
exchanger are shown at 10, 11, 12, 13, 14 and 15. Referring to the
lowest plate 10, for simplicity, each plate in the exchanger is of
elongated rectangular sheet and parts of the two longer sides only
are shown for the plate 10. In the peripheral region of each plate,
in this embodiment, a flat channel structure 16 is formed for the
reception of a sealing gasket on either side. In this example, the
main face area of the plate 10 within the rectangular gasket
channel formation 16 is embossed with a herring-bone pattern of
shallow V-shaped hill and valley corrugations 17. Each corrugation
17 consists of two oppositely-inclined surface portions 17a, 17b
which form a straight line of intersection 17c, which forms a hill
on one side of the plate and a valley on the other side of the
plate. Circular or other apertures are provided in advantageous
locations on the plate 10 (not shown) for use as the ports and the
channel formations 17 are appropriately arranged adjacent the
respective ports, so that the appropriate connections are provided
in a convenient manner.
In the embodiment illustrated, the alternate plates 10, 12 and 14
have the basic structure which has just been described above in
relation to plate 10 and it will be noted that the plates are
arranged to have the herring-bone pattern facing alternately in one
direction and the other, the plates 10 and 14 being identical in
form and arrangement and the plate 12 having the same form but
being reversed so that its herring-bone pattern faces the other
way.
Each of the alternate plates 11, 13 and 15 is basically identical
with the cooperating plate below it in both portions and
dimensions, but each of these plates 11, 13 and 15 is provided with
small reversed corrugation areas which constitute abutments
disposed within the valleys of the corrugations. These abutments
function as a secondary set of contact points. As shown for the
plate 11, a secondary pressing is effected on the plate so that
portions of the hill structures of the corrugations 17 are provided
with integrally formed valley formations 18 which have their
intersecting lines 18c between the opposed faces 18a and 18b
directed at right angles to the hill and valley crest lines 17c of
the main corrugations. The subsidiary corrugations as shown are
partial, though they can be complete in that the relevant portions
of the plate are completely reversed in hill-and-valley corrugated
formation. The extent of this secondary shaping can be such that
hills are formed which are higher than the primary hill
structure.
The plates are arranged in pairs of two plates that are similarly
oriented. As shown in FIG. 1, pairs are formed by plates 10 and 11,
12 and 13, and 4 and 15. Each pair of plates has an orientation
opposite that of the adjoining pairs. As best shown in FIG. 3, the
spacings provided between the plates 11 and 12 and between the
plates 13 and 14 (which constitute parts of one of the flowpaths
through the heat exchanger) can be regarded as conventional when
they occupy a first cooperative relationship in that the spacing is
governed by a primary set of contact areas where the hill ridge
lines of intersection 17c of the plate cross and contact the hill
ridge lines of intersection 17c of the adjacent plate. A standard
thickness gasket 19 is provided between these plates, as shown best
at FIG. 2. It can be seen from FIG. 1 in particular that the
directions of the main corrugations 17 in the superposed portions
of the plates 11 and 12 and 13 and 14 respectively are differently
oriented so as to provide this standard spacing. The spacing which
is produced between the plates 10 and 11, the plates 12 and 13 and
the plates 14 and 15 respectively is less than this standard
spacing, because the main ribs on the corrugations 17 in superposed
areas similar and, therefore, internesting occurs to the extent
permitted by the subsidiary corrugations 18 in the plates 11, 13
and 15. When the plates occupy this second possible cooperative
relationship, the ridges 18c of the subsidiary corrugations contact
with a secondary set of points spaced along the ridges 17c of the
plates underlying the plates 11 and 15 respectively. In this
embodiment the flow channels between the cooperating plates have a
smaller cross-sectional area when they occupy this second
internested relationship than when they occupy the first
non-internested relationship. This is due to the dimensions of the
abutments 18. It can be seen from the figures that a narrower
gasket 20 is provided for these plates. The spaces between the
plates 10, 11, 12, 13 and 14, 15 constitute successive portions of
the other flowpath through the heat exchanger. By this simple
modification of each alternate one of the plates in a stack of
plates, with appropriate sizing of the gaskets a relatively large
flowpath for one of the fluids is given and alternates with a
relatively narrow flowpath for the other of the fluids, as can be
readily seen in FIG. 3.
* * * * *