Note: Descriptions are shown in the official language in which they were submitted.
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The Dl closure
The present invention relates to a heat exchanger of
the type comprising a plurality of generally rectanyular plates
arranged adjacent to each other and provided with turbulence-
generating corrugations, said plates enclosing sealed passages
for receiving two heat exchanging nedia flowing therethrough in
mutually incllnecl flow directions.
By arranging the corruga-tions of adjacent plates in-
clined to each other, a large number of supporting points are
~rovided in which the ridges of adjacent platcs abùt. In known
heat exchangers of this kind, the corrugations are usually ar-
ranged in a so-called herrincJbolle pattern, which means tllat the
riclges and grooves orming the corrugations are brokcn along the
lonc3itudinal axis of the plate and on both sides of s.lid a~is cx-
tend at the sal~le an(Jle thcrcto. In this type of p]ate, the
anc31e between the corrugations oE adjacent plates is providecl by
rotating every other plate 180 in its own plane.
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The symmetrical corruga-tions of the plates of these
known heat exchangers provide for equal thermal properties of
all the heat exchanging passages. This is the case even when two
different kinds of plates are used alternatively, i.e., plates
having differing angles of corrugation. What has been said
above applies even for diagonal flow, whlch means -that each of
the heat exchanglng media flows between openings provided at dl-
agonally opposite corners of the plates.
It is often deslrable to provlde heat exchanglng
passages having different thermal properties for the two heat ex-
changlng media in order to fulfill different objectives of heat
exchange ln the most efficient manner. A proposed solution for
attainlng this purpose is to provide alternate plates in the heat
exchanger with a corrugation that is asymmetrlcal wi-th ~espect
to the central plane o the plate, so that the grooves have a
larger volume on one side of the plate than on the other. In
this way, it is possible to provide a heat exchanger ln whlch the
passages for the two media have different volumes and consequently
differing thermal properties. However, -this known solution is
disadvantageous ln that the corrugation cannot be effectively
deslgned wlth regard to turbulence generation as well as pressure
reslstance.
The present lnvention has for its principal object to
provide different thermal properties of the passages for the two
heat exchanging media without any reduction of the turbulence-
generating capacity or mechanical strength of the corrugations.
This has been obtained by a heat exchanger of the first-
men-tioned kind which is generally characterized in that the cor-
rugations ex-tend in such directions that they form on an average
a wider angle with the flow direction of one of the media than
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with -tha-t of the other, whereby the passages for -the two media
provide mutually difering flow resistances.
The invention will be described in more detail below
with reference to the accompanying drawings, in which Fig. 1 is
an exploded, diagrammatical perspective view of a conventional
plate heat exchanger, Fig. 2 is a corresponding view of an embodi-
ment o the heat exchanger according to the invention, and Figs.
3-6 are diagrammatical plan views of preferred embodiments of
heat exchanging plates to be used in the heat exchanger according
to the invention.
The heat exchanger shown in Fig. 1 comprises a series
of plates 1 and 2 arranged alternately and which are to be
clamped together in a conventional manner in a frame-work which,
for the sake of simplicity, has been omitted in the drawing. Two
heat exchanging media A and B are conveyed via openings 3 and ~,
respectively, to and from the heat exchanging passages formed be-
tween the plates, as is indicated by dashed lines. As can be
seen, the inlet and outlet openings for each medium are disposed
at diagonally opposite corners of the plates, whereby the flow
directions of the media A and B are mutually inclined.
The plates 1 and 2 in Fig. 1 are provided with corru-
gations in a so-called herringbone pattern, as indicated at 6.
The corrugation creases extend at the same angle a relative to
the longitudinal axls 5 of the plates on both sides of said axis.
To provide a mutual angle between the corrugat:ions of adjacent
plates, alternate plates are rotated 180 in their own planes.
It is obvious that in a heat exchangQr assembled from
plates 1 and 2 as defined above, which are completely symmetrical
with regard to their longitudinal axis, all the heat exchanging
passages will have identical thermal properties.
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The heat exchanger according to the invention (Fig. 2)
comprises a series of plates 11 and 1~ shown on a larger scale
in Fig. 3. The heat exchanging media A and B are conveyed to and
from the heat exchanging passages via openinys 13 and 14, respec-
tively, situated at diagonally opposite corners of the plates.
As in Fig. 1, the heat exchange thus ta]ces place in cross~flow.
The plates are provlded with gaskets 18 as usual. The plates are
further provided with corrugations in a herringbone pattern, the
breaking line of which coincides with the longitudinal axis 15 of
the plates. This "breaking line" is an imaginary line extending
through the apices of the herringbones, where their two legs are
joined. The diagrammatically indicated corrugation creases 16
and 17 are inclined to the longitudinal axis 15 at angles b and
c, respectively, the angle c being considerably wider than the
angle b. With the exception of the gasket arrangement 18, the
plates 11 and 12 are ide~tical, alternate plates being rotated
180 in their own planes.
By comparison of the angles of the corrugations with
the flow directions of the media A and B through the heat exchang-
ing passages, it is found that medium A meets the corrugations ata considerably wider angle than medium B. Medium A, which flows
between openings 13, thus has a flow direction generally trans-
verse to the corrugations, while the flow direction of medium B
between openings 14 forms a relat-ively small angle with the corru-
gations. The flow resistance is therefore considerably higher for
medium A than for medium B, and the thermal properties of the
passages for the two media are therefore considerably different
from each other. The difference of thermal properties is because
the angles b and c are different.
Figs. 4-6 illustrate further embodiments of heat ex-
changing plates adapted to be arranged alternately in the same
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way as described above. The plates differ from those shown in
Fig. 3 only wlth respect to the shape of the corrugation pattern,
and therefore only this will be described.
The two plates 21 and 22 in Fig. 4 have identical corru-
gations, alternate plates being turned :L80. In this case thecorrugation creases 23 and 24 are broken along a breaking line 26
and form angles d and e therewith, respectively. The breaking
line 26 in turn forms an angle f with the longitudinal axis of the
plate. The desired effect on the thermal properties of the
passages accordlng to the invention is obtained provided that the
corrugation creases 23 and 24 extend at different angles relative
to the longitudinal axis 25.
Fig. 5 illustrates two plates 31 and 32 provided with
unbroken corrugations 33 and 34 forming angles g and H, respec-
tively, with the longitudinal axis 35. ~rovided that theseangles differ in width, the thermal properties of the heat ex-
changing passages will be different.
Even the plates 41 and 42 shown in Fig. 6 are provided
with unbroken corrugations 43 and 44 which on both plates form an
angle 1 with the longitudinal axis 45. Since the corrugations in
this case are parallel and thus will not cross and abut each
other, supportiny points between the plates are instead provided
in a known way by means of transverse ridges (not shown~ between
the corrugation creases. It is easily realized that a passage
extending between openings 46 (i.e., generally parallel to the
corrugations) offers a considerably less flow resistance than a
passage extending generally transverse to the corrugations between
openlngs 47.
The plates in Fig. 6 are shown square. This makes it
possible to obtain the biggest possible difference of thermal
properties of the passages for the two media. This is because
~he flow directions of the media in this case form the widest
¦possible mutual angle (i.e., 90). With a corrugation arranyed as
¦in Fig. 6l one of the media will flow generally parallel to the
¦corrugation, which provides for the lowest possible flow re-
S sistance, while the other medium will flow generally -transverse to
the corruyation, which offers maximum flow resistance. By varying
the angle 1, it is possible to adapt the thermal properties of
the passages mutually as required. The difference is biggest
when 1 is 45, as in Fig. 6, and is reduced towards zero when the
angle approaches O or 90.
The square format can of course be used with a different
corrugation pattern than that shown in Fig. 6.
A person skilled in the art will easily realize that
other corrugation patterns than those describecl above are possible
within the scope of the invention.
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