DE602005006296T2 - HEAT EXCHANGERS WITH SPECIAL PLATES - Google Patents

Abstract

The invention concerns a plate heat exchanger, comprising a plurality of plates (2-5) assembled to define between them fluid circulating channels (6-8). Each plate comprises undulations (25) or corrugations defined between apex lines of corrugations (35) and base lines of corrugations (32). At least one part of the plates comprises recessed (30, 31)and bump (33) deformations located between the apex and base lines of corrugations. Said exchanger is characterized by the positioning of said bumps and recesses relative to contact points (51, 54) between adjacent plates (48, 25) delimiting the channel.

Description

Technical part

The The invention relates to the field of heat exchangers, in particular the Plate heat exchanger. Such heat exchangers consist of a stack of corrugated sheets that are joined together around each other channels for the Fluid circulation according to two entangled circles to build.

The The invention relates in particular to an improvement that the arrangement of surveys formed on these plates.

State of the art

Plate heat exchanger generally include beads that form corrugations, so that with the adjacent plate delimited channel a variable Cross section has. In general, these beads are with respect to Orbital direction of the fluid obliquely and have an inclination corresponding to the beads of the adjacent Plate is opposite. These beads are common, however not necessarily, in the form of chevrons or angles. These different geometric variants have the goal of forming channels whose function is the flow disturb, to the heat exchanges too improve.

The applicants have in the Scriptures EP 0 737 296 described an improvement for this heat exchanger type, which is that on the one hand the heat losses and on the other hand, the dangers of contamination of the heat exchanger in the areas with smaller passage can be improved. This improvement consists in that deformations are formed on the beads, which additionally disturb the circulation of the fluid. These deformations are made in the manufacture of the plate, which is generally made by deep drawing. These deformations may be recessed or raised relative to the main shaft, provided that the deformations forming a depression on one side of the plate form a raised deformation on the opposite side of the same plate.

According to the teaching In this document, the raised deformations are preferably near the points of contact located between plates corresponding to the zones in which the speed of the fluid is lowest. These zones therefore form dead or stagnant zones where deposits can occur. The Positioning of the raised deformations near these contact points allowed it is to reduce the volume of these dead zones and thus to limit the risk of formation of deposits without, however, the To increase load losses too much.

Out Trying has shown that the positioning of the sublime Deformations close to the contact points between plates not really satisfying, in particular because of an increase in the Load losses. Furthermore corresponds to the existing inside a channel raised deformation a recessed deformation on the adjacent channel, the limited positive effect of the surveys in this adjacent channel.

aim It is the object of the present invention to provide the benefits of this type of heat exchanger with regard to all for the effectiveness of the heat exchanger representative To optimize factors, d. H. the heat exchange coefficient so as the load losses generated, and as far as possible with one low degree of contamination is compatible.

Summary of the invention

The The invention relates to a heat exchanger, which has a plurality of corrugated plates joined together to form fluid circulation channels with each other.

In a known manner, each plate comprises beads formed between crest crest lines and bead bottom lines. All or part of these plates include, as in the Scriptures EP 0 737 296 , recessed and raised deformations located between the crest crests and ground lines.

The Invention consists in a more accurate positioning of the various recessed and raised deformations with respect to the lines of the contact points between the neighboring plates. This localization is on the "front side" of a disk, i. H. on the side facing a canal, and inside a basic cell defined between four consecutive Contact points with the channel adjacent adjacent plate is formed.

• – D₁ der in einer zur Hauptfläche der Platte parallelen Ebene und parallel zu der Sickenscheitellinie gemessene Abstand ist zwischen: – dem Mittelpunkt der erhabenen Verformung, der einem der Kontaktpunkte am nächsten ist; – einem Bezugspunkt, der in gleichem Abstand von der Sickenscheitellinie und der Sickenbodenlinie gelegen ist, wobei dieser Bezugspunkt mit dem Kontaktpunkt in der Strömungsrichtung des Fluids in einer Linie liegt.
• – D der in einer zur Hauptfläche der Platte parallelen Ebene und parallel zur Sickenscheitellinie gemessene Abstand ist zwischen: – dem Mittelpunkt der erhabenen Verformung, die einem der Kontaktpunkte am nächsten ist; – dem Mittelpunkt der vertieften Verformung, die in der Richtung der Sickenscheitellinie am nächsten ist.

Thus, the raised and recessed deformations are located so that the criterion N = D ₁ / D is between 0.35 and 0.8, where:

• D _{1 of} the distance measured in a plane parallel to the major surface of the plate and parallel to the crest of the crest is between: the center of the raised deformation closest to one of the points of contact; A reference point equidistant from the crest line and the bead bottom line, said reference point being in line with the point of contact in the flow direction of the fluid.
• - D in a plane parallel to the main surface of the plate and parallel to the crest line measured distance is between: - the center of the raised deformation closest to one of the contact points; The center of the recessed deformation closest in the direction of the crest of the crest.

In other words, the invention is the localization of the raised deformations at an intermediate height between the contact points and not, as the patent EP 0737296 taught, in the vicinity of the contact points, which corresponds to a criterion N substantially zero.

The Localization of these raised deformations according to the invention leads surprisingly First, to improve the heat exchange performance and Furthermore to reduce the load losses in the heat exchangers with such plates are measured.

So became the effectiveness of a plate heat exchanger in practice determined by the transmitted Power was combined with the measured load losses. The compared to corrugated plates without recessed and raised deformations measurements carried out show an improvement in the overall efficiency of the heat exchanger in the considered criteria range. This improvement is achieved even about ten percent at the optimum of the criterion that with estimated at about 0.55 at chevrons configurations, further down in the description a particular embodiment to be discribed.

Further the improvement in terms of load losses results in a reduction of several ten percent in the vicinity this optimum.

Practically can the deformations take different different forms, depending on the thermoforming process and elongation, the the material used can be subjected. Independent of The shape of these deformations will be used for the assessment of the characteristic criterion required measurements, by the volume of these deformations with respect to the general shape the wave is defined. In particular, this general form can be determined in a zone that is free from recessed and sublime Deformations is. This volume will then be at the main level of the Plate projected and the focus of this projection is now considered as the center of deformation.

Practically can diverse Arrangements of recessed and raised deformation are used however, it is preferable to repeat the positioning patterns to maintain the formation of preferred ways and the occurrence Avoid too stagnant zones.

Out the various geometries that are satisfying, one has those identified in which the raised deformations alternately and staggered on either side of the crest line, considering the front of the plate, d. H. that, which is in direct contact with the fluid in the channel under consideration.

Of course it corresponds this arrangement of the formation of recessed zones near the bottom line of the sill with the same alternating distribution, which is the opposite Side of the plate. In this preferred geometry at the level of the front the plate can the recessed deformations advantageously symmetrical to both Be distributed sides of the bottom floor line. These recessed deformations the front corresponds to raised deformations near the crest lines on the opposite side.

Of course they can various raised and recessed deformations at varying levels the height the bead is positioned between the crest line and the bottom line be. However, pay attention to the volume of the raised deformations not that defined by the different crest lines Main level exceeds, to allow a comfortable stacking of the individual plates.

In In practice, the characteristic criterion N can essentially be determined be constant on the substantial part of the exchange surface of the plate, but it is also possible To form plates that have different zones, the different possess characteristic criteria.

So can in a special case the front of the plate in one first zone possess raised deformations, alternating and staggered on either side of the crest line, and thus a characteristic criterion in advantageous areas have. In a second zone are the raised deformations however, distributed symmetrically to both sides of the crest line. This dual configuration allows it to be in the two this way defined zones create different load losses. One thus forms zones of the privileged passage of Fluid that can compensate for the fact that the fluid is on the enter the channel on the same side of a long edge of the plate and get out of it.

In practice, the heat exchanger can be formed by the assembly and stacking of identical plates, but also from different plates, depending on the desired heat meaustauscheigenschaften.

Further can the identical plates depending on the orientation of the sides of the plates, which is a characteristic criterion in an advantageous range own, be arranged in different ways.

So can the plates are joined together in a first variant, around channels to form a first type, which can be called "symmetrical", by one another opposing surfaces is limited, which is a substantially identical characteristic Have criterion.

If the channels defined by the preferred pages are particularly advantageous in terms of of the exchange coefficient and the load losses are as follows from that, the neighboring channels, with the backs the plates are formed, in turn, have inferior properties. These heat exchangers formed with this type of stacking are in particular for heat exchangers which flows through fluids that are different flow typologies own, in particular heat exchangers of the evaporator type or capacitor.

It may also be about liquid / liquid heat exchangers act in which the channels with less load losses, take up the circulation with higher throughput.

at another embodiment can the plates joined together be to channels of to form a second type, called asymmetric can, with the arrangement chosen is that the sides of the plates, the same characteristic Have criteria N, all directed in the same direction.

With in other words, the channels are now essentially similar Properties as they pass through the front of a page characterizing plate are limited and on the other side by a back, which is less powerful from the outset.

Of the formed in this way heat exchanger has two circles of very similar Performance and can therefore be adapted to any type of liquid / liquid heat exchangers.

in the Case of the already mentioned Plates that have zones of different natures on the same side, these are to be stacked in order, as mentioned, to be essentially parallel Sections formed channels of the first and second types already mentioned.

Even though it is easier, heat rush to make identical plates by placing them in dependence of the channel type one wishes to make, turn and turn covers the invention also variants in which an assembly of Plate molds that have different properties makes.

Further can change the shape of the corrugations depending on desired Be adapted application and the invention is by no means on the chevron or angle-shaped Beading limited, like they are shown in the accompanying figures.

Brief description of the figures

The Type of execution The invention, as well as the resulting benefits go out the following description of embodiments, wherein is referred to the accompanying drawings. In this show:

1 a general schematic perspective view showing the formation of various plates, which are provided in a plate heat exchanger.

2 and 3 Schematic overall perspective views of a plate shown with its front and its back, respectively.

4 a schematic perspective detail view showing the positioning of the characteristic depressions and elevations.

5 a schematic plan view of 4 ,

6 and 7 Charts showing the change of various representative parameters of the heat exchange depending on the characteristic criterion N.

8th . 9 and 10 Representations of the assembly of plates according to the invention according to different variants.

Type of implementation of invention

As schematically in 1 is shown, the heat exchanger ( 1 ) different plates ( 2 - 5 ) joined together to communicate fluid circulation channels ( 6 - 8th ) to build.

More precisely, each plate ( 2 - 5 ) includes four holes ( 10 - 13 ) for connection to the inlet and outlet lines of two fluid circuits ( 20 . 21 ; 22 . 23 ). On each plate a circumferential seal ( 14 ) the sealing of the channel formed by only two of the Bohrun in this channel be included. In the illustrated form are the one and the same channel associated holes ( 10 . 11 ; 12 . 13 ) on the same large side of the plate ( 2 However, the invention also covers variants in which the two holes associated with a channel are located on a diagonal of the plate.

As in 1 illustrated, each plate comprises ( 2 - 5 ) Beading ( 25 ) in the form of simple chevrons or angles. In other variants, not shown, the beads may also be in the form of multiple chevrons. The plates are alternately pivoted through 180 ° about their center so that the chevron-shaped beads on the two facing sides of the plates at the level of one and the same channel are arranged opposite to each other to increase the degree of disturbance of the circulating fluid in the channel.

When two channel defining plates are opposed to each other, their respective bead apex lines are in contact, as in FIG 4 is shown at the level of contact points.

According to the teaching of the patent EP 0 737 296 The plates include recessed and raised deformations distributed on the beads. In all figures, only a portion of these depressions and these surveys is shown to avoid overcharging the drawing and not to affect the understanding of the invention.

Because of agreements are, as in the 2 . 3 and 4 is shown, the raised deformations, which thus correspond to surveys with respect to the considered side of the plate, represented by ovals. The recessed deformations are represented by rectangles and thus correspond to deformations which are recessed inwardly into the plate viewed on the relevant side.

As in 2 shown, are the recessed deformations ( 30 . 31 ) near a bead bottom line ( 32 ), while the raised deformations ( 33 . 34 ) near a crest line ( 35 ) are arranged. On the front side ( 36 ) of the plate of 2 are the recessed deformations ( 30 . 31 ) with respect to a bead bottom line ( 32 ) are located substantially opposite each other. In contrast, the raised deformations ( 33 . 34 ) with respect to its crest line ( 35 ) arranged offset.

The backside ( 46 ) of the same plate is in 3 shown. It is found that the recessed deformations ( 30 . 31 ) of the front raised deformations ( 40 . 41 ) on the back, which are on either side of the crest line ( 42 ) on the back side ( 46 ) are located opposite each other.

In the same way, the raised deformations ( 33 . 34 ) of the front ( 36 ) recessed deformations ( 43 . 44 ), on the back side ( 46 ) seen. These recessed deformations ( 43 . 44 ) are, if one the back ( 46 ), on both sides of the bead bottom line ( 45 ), this bead bottom line of a crest line ( 35 ) on the front side ( 36 ) corresponds.

As already mentioned, the invention is based on a special positioning of the recessed and raised zones with respect to the contact points between plates. So comes the plate ( 25 ), as in 4 shown with the plate ( 48 ), which is in contact with it, at the level of a plurality of contact points in order to connect the channel ( 26 ) to build. These contact points are at the interfaces of the crest lines ( 35 ) of the plate ( 25 ) with the bead crest lines ( 49 ) of the plate ( 48 ). The different contact points ( 51 - 54 ) define fundamental cells which have a general parallelogram shape, in particular a diamond shape, when the chevrons of the two opposing plates have the same inclination. These diamonds can be square in shape when the chevrons are perpendicular from one plate to another.

The Localization of the recessed and sublime patterns is after projection made on a plane P, parallel to the main plane of the plate which is also at the level defined by all contact points is parallel.

The recessed and raised deformations are measured at this level by projecting their focus on the P plane. So the survey ( 33 ) to the point ( 63 ) of the plane P, while the recessed deformation ( 30 ) to the point ( 60 ) of this level is projected. The position of these depressions and elevations according to the invention with respect to a reference point ( 65 ) certainly. This reference lies on the plate ( 25 ) in the middle between a bead crest line ( 35 ) and a bead bottom lines ( 32 ).

This reference point derives from the contact point ( 52 ) as a point which is in line with this direction F in the direction of flow of the fluid.

The projection ( 66 ) of this reference point ( 65 ) is shown on the level P.

The invention consists in a positioning of elevations and depressions with respect to this reference point. So this reference point is from a point of flow of the fluid behind a con tact zone between plates. The distances between elevation and depression are determined by projection onto the bead line ( 35 ). So corresponds to in 4 illustrated distance D the measured parallel to the bead peak line distance between the raised deformation ( 33 ) and the successive recessed deformations ( 30 . 31 ).

The distance D ₁ corresponds to the distance between the projection also measured parallel to the bead line (FIG. 63 ) of the raised deformation ( 33 ) and the projection ( 66 ) of the reference point ( 65 ).

According to the invention, good results have been found with regard to the operation of the heat exchanger when the ratio D ₁ / D is between 0.35 and 0.80 and, more specifically, close to 0.55. These values apply to plates whose chevrons have an angle of about 60 °. The optimum of this criterion N can, in particular at different chevron angles ( 10 ) slightly different.

6 shows the change of a parameter to measure the performance of a heat exchanger. Thus, the efficiency parameter ξ is determined by comparing the performances of a plate used in a heat exchanger according to the invention with the performances of a plate having no recessed and raised deformations. Specifically, this parameter ξ is calculated by measuring the ratio of the exchange power divided by the ratio of the load losses measured on these two plate types, the ratio of load losses depending on the type of heat exchanger being approximately 0.33 to 0, 37 is levied.

Thus, the criterion ξ, shown in 6 Very clearly, a considerable gain of about 10% in the considered range of the criterion N, with an optimum occurring when the criterion N is in the vicinity of 0.55.

It should be mentioned in this regard that the patent EP 0 737 296 teaches the positioning of the raised deformations just behind the contact points between plates, which corresponds to a situation in which the characteristic criterion N is close to 0.

In addition show the load losses, which are measured at plates, in one heat exchanger according to the invention used to be surprising Way a very significant improvement in the considered area of the characteristic criterion. These load losses are smaller than about 30% compared to the load losses that in teaching of the cited prior art patent be measured.

According to another aspect of the invention, the characterizing plates may be arranged to each other in different configurations, depending on the sides which they face each other. To understand the 8th - 10 To facilitate, only the raised zones (with dots) around the crest lines were shown. So are in the in 8th configuration shown the various plates arranged so that they have on their visible side in the figure pages on which the raised deformations ( 70 ) symmetrical with respect to the crest lines ( 71 ) are arranged. The visible sides of the plates of 8th correspond to the in 3 displayed visible side.

In the entirety of the plates ( 69 ) from 8th all their identical pages are directed in the same direction. These plates are stacked by pivoting about their centers from one plate to another.

From this one deduces that the hidden side of each of the plates ( 69 ) the in 2 illustrated configuration, in which the recessed deformations are each arranged symmetrically with respect to the bead bottom lines. In addition, the raised deformations on this hidden side (the not shown recessed zones on the visible sides of the 8th Corresponding to the crest lines, which are opposite to the visible sides of the plates of 8th are located, arranged alternately and staggered.

The channels formed in this way ( 73 ) thus have properties that are substantially identical in the two fluid circuits.

One can also use an opposite configuration, as in 9 is shown. In this case, the two outermost plates shown ( 80 . 82 ) has a visible page that is in 2 illustrated configuration in which the raised deformations ( 83 . 84 ) with regard to the crest lines ( 85 ) are arranged alternately and staggered.

In contrast, the intermediate plate ( 81 ) an in 9 visible page on which the configuration of 3 corresponds, in which the raised deformations ( 86 . 87 ) with regard to the crest lines ( 88 ) are arranged symmetrically. It is assumed that the between the first plate ( 80 ) and the second plate ( 81 ) formed channel ( 89 ) has two substantially identical sides, the visible side of the intermediate plate ( 81 ) corresponds. At the height of this channel ( 89 ) the raised deformations are thus arranged symmetrically on each of the opposite sides with respect to the crest of the crest.

Conversely, in the channel ( 90 ) located between the middle plate ( 81 ) and the furthest plate ( 82 ), the two opposing sides have the same configuration as that of FIG 2 equivalent.

In this case, the raised deformations ( 84 . 85 ) of the opposite sides are arranged alternately and staggered with respect to the crest line. It is therefore understood that the total heat outputs as well as the load losses of the two channels formed in this way ( 89 . 90 ) are different and better designed for the creation of heat exchangers that have a flow typology that is different between the two circles, such. B. evaporators or condensers.

Of course, the two configurations described above can be combined within one and the same disk as in 10 is shown. Thus, one and the same disk can have both configurations on one and the same side. More specifically, as in 10 is shown, the middle plate ( 94 ) on one side raised deformations ( 95 ) with respect to the crest lines ( 96 ) are arranged symmetrically.

In addition, the raised deformations ( 97 . 98 ) alternately and staggered on the opposite side. As a result, the load losses generated in this way in the two parallel longitudinal sections ( 99 . 100 ) of the channel ( 101 ) different. This arrangement is optimized to reduce the load losses associated with the section ( 100 ) of the channel corresponding to the points of fluid entry and exit ( 103 . 104 ) is furthest away so that the throughput on the width of the channel is homogenized as much as possible.

The individual plates of the heat exchanger stacked by pivoting in the same plane around its center become.

Out From the above it follows that the plate heat exchangers according to the invention Have performances that significantly higher than the plate heat exchanger of the prior art, both in terms of heat exchange coefficient as in terms of height of load loss.

The heat exchangers can be built by identifying plates on different Ways can be arranged, which are adapted to the fluid type and throughput type are the heat exchangers flow through should.

Claims (10)

Heat exchanger comprising a plurality of plates ( 2 - 5 ) joined together to communicate fluid channels ( 6 - 8th ), each plate waves ( 25 ) or corrugations formed between bead crest lines ( 35 ) and bead bottom lines ( 32 ) are formed, wherein at least a portion of the plates recessed ( 30 . 31 ) and sublime ( 33 ) Has deformations, which are located between the crest crests and bottom lines, characterized in that on at least one plate at the level of their front side facing a channel and in the interior of a basic cell, between four successive contact points ( 51 . 54 ) with the adjacent plate delimiting this channel ( 48 ), the sublime ( 33 ) and deepened ( 30 . 31 ) Deformations are located such that the criterion N - D ₁ / D is between 0.35 and 0.8, wherein: - D1 is in a plane parallel to the main surface of the plate (P) and parallel to the crest of the crest ( 35 ) measured distance is between: - the center of the raised deformation ( 33 ), one of the contact points ( 52 ) is closest; - a reference point ( 65 ) equidistant from the crest line ( 35 ) and the bead bottom line ( 32 ), this reference point ( 66 ) with the contact point ( 52 ) is in line with the flow direction of the fluid. D in a plane parallel to the main surface of the plate and parallel to the crest of the crest ( 35 ) measured distance is between: - the center of the raised deformation ( 33 ), which is one of the contact points ( 52 ) is closest; - the center of the recessed deformation ( 30 ) in the direction of the crest line ( 35 ) is closest. Heat exchanger according to claim 1, characterized in that the raised deformations ( 33 . 34 ) at least part of the front of a plate ( 25 ) are alternately distributed and on both sides of the crest ( 35 ) are offset. Heat exchanger according to claim 1, characterized in that the recessed deformations ( 30 . 31 ) at the level of at least a part of the front side of a plate symmetrical to both sides of the bead bottom line ( 32 ) are distributed. Heat exchanger according to one of claims 2 and 3, characterized in that at the level of the front side of a plate ( 94 ) the raised deformations ( 97 . 98 ) in a first zone ( 100 ) are alternately distributed and on both sides of the crest ( 96 ) and the raised deformations ( 95 ) in a second zone ( 99 ) on both sides of the crest line ( 96 ) are distributed symmetrically. Heat exchanger according to claim 1, characterized in that the plates ( 80 - 82 ) are connected to the channels of a first type ( 73 ), which are formed by facing surfaces having a substantially identical criterion N. Heat exchanger according to claims 2 and 3, characterized in that the plates ( 69 ) are merged to channels ( 73 ) of a second type, wherein the sides of the plates having substantially identical criteria are directed in the same direction. Heat exchanger according to claim 4, characterized in that the plates ( 94 ) are joined together to define channels formed by substantially parallel portions of the first and second types. heat exchangers according to claim 1, characterized in that it consists of identical Plates exists. Heat exchanger according to claim 1, characterized in that the beads ( 25 ) are in the form of simple or multiple chevrons or angles. Heat exchanger according to claim 1, characterized in that the chevrons or angles ( 25 ) have an opening angle of 60 °.