CN115325864A

CN115325864A - Plate with asymmetric corrugation for plate heat exchanger

Info

Publication number: CN115325864A
Application number: CN202210477789.4A
Authority: CN
Inventors: 赫尔格·尼尔森
Original assignee: Danfoss AS
Current assignee: Danfoss AS
Priority date: 2021-05-10
Filing date: 2022-04-28
Publication date: 2022-11-11
Also published as: EP4089359A1; US20220357109A1

Abstract

The invention discloses a plate (2) for a plate heat exchanger (1). The plate (2) is provided with a plurality of corrugations (8), the cross-section of the plate (2) thereby defining a plurality of peaks (9) and valleys (10), the peaks (9) and valleys (10) defining flow paths along the surface of the plate (2). The peaks (9) and/or valleys (10) have an asymmetric shape with respect to a centre line (11, 12) intersecting the apex of the peaks (9) and/or valleys (10). The invention also discloses a plate heat exchanger (1) comprising a plurality of such plates (2) arranged in a stacked configuration, wherein peaks (9) and valleys (10) formed in the plates (2) define flow paths between the plates (2).

Description

Plate with asymmetric corrugation for plate heat exchanger

Technical Field

The present invention relates to a plate for a plate heat exchanger. The plate is provided with a plurality of corrugations defining flow paths along opposite sides of the plate. The invention also relates to a plate heat exchanger comprising a plurality of such plates.

Background

The plate heat exchanger comprises a plurality of stacked plates, each plate being provided with a corrugated pattern. Thereby defining flow paths between the plates and heat exchange can take place through the plates via the respective flow paths between fluids flowing along opposite sides of the plates.

The size and shape of the flow path is determined by the design of the corrugated pattern of the plates. In a cross-sectional view of one of the plates, the corrugation pattern defines peaks and valleys that are generally identical or similar to each other, thereby defining identical or very similar flow paths along opposite sides of the plate. Furthermore, the peaks and valleys defined by the corrugation pattern are typically symmetrical, i.e. the portions of the sheet extending from the apex of the peak or valley are substantially identical in terms of inclination angle, radius of curvature, etc.

The plate heat exchanger may be, for example, in the form of a gasket heat exchanger, wherein the plates are held together under tension in a non-permanent manner, i.e. the plates may be separated from each other. Alternatively, the plate heat exchanger may be in the form of a brazed heat exchanger, wherein the crests of the corrugation pattern are brazed or welded to each other, i.e. the plates are joined to each other in a permanent manner.

The same flow path along opposite sides of the plate has the following result: the pressure conditions in the fluid flowing in the respective flow paths are also the same or very similar. For example, the pressure drop across the heat exchanger is substantially the same for each heat exchange fluid. However, it is sometimes desirable that the pressure drop of the hot fluid be different from the pressure drop of the cold fluid in order to obtain the desired heat transfer in the heat exchanger. This can be achieved, for example, by designing the corrugation pattern in such a way that the peaks differ from the valleys. This results in the peaks or valleys being relatively large, which may reduce the strength of the heat exchanger. To compensate for this, the thickness of the plate may be increased at least at the weakened portions, which results in poor heat transfer through the plate.

Disclosure of Invention

It is an object of embodiments of the invention to provide a plate for a plate heat exchanger, wherein an improved heat transfer in the heat exchanger is obtained.

It is a further object of embodiments of the invention to provide a plate heat exchanger with improved heat transfer capacity.

According to a first aspect of the invention, a plate for a plate heat exchanger is provided, which plate is provided with a plurality of corrugations, the cross-section of the plate thereby defining a plurality of peaks and valleys, which define flow paths along the surface of the plate, wherein the peaks and/or valleys have a shape that is asymmetric with respect to a centre line that intersects the apexes of the peaks and/or valleys.

Accordingly, a first aspect of the invention provides a plate for a plate heat exchanger, i.e. a heat exchanger as described above comprising a plurality of stacked plates. The plate is provided with a plurality of corrugations. Thus, when the plates are stacked to form a plate heat exchanger, flow paths are formed along opposite sides of the plates, and heat exchange may occur between fluids flowing in the flow paths formed along the opposite sides of the plates. Due to the corrugated structure, the cross-section of the plate defines a plurality of peaks and valleys, and these peaks and valleys define flow paths on opposite sides of the plate.

The peaks and/or valleys have a shape that is asymmetric about a centerline that intersects the apex of the peak and/or valley.

In this context, the term "apex" should be interpreted as meaning the position of the corrugated structure constituting the extreme value (i.e. the distance between the sheet and the average plane of the sheet is the greatest).

Since the peaks and/or valleys have a shape that is asymmetric about a centerline that intersects the respective apex, the shape of the plate portion in an area that approaches one of the apexes from one direction is different from the shape of the plate portion in an area that approaches the apex from the opposite direction. This results in the flow paths defined by the peaks and valleys of the corrugations also being asymmetric. Furthermore, the consequence of the asymmetry is that the flow paths formed on one side of the plate are different from the flow paths formed on the opposite side of the plate. Thus, the pressure conditions prevailing in the heat exchange fluid flowing along the opposite sides of the plates are also different from each other. For example, the pressure drop of the hot fluid is different from the pressure drop of the cold fluid when passing through the heat exchanger, so that the desired heat transfer between the fluids can be obtained. This is obtained without significantly weakening the panel, because the peaks and/or valleys are enlarged on one side only, due to the asymmetry of the peaks and/or valleys. Thus, the thickness of the plate does not need to be increased to compensate for this weakening.

Furthermore, when stacking identical plates to form a plate heat exchanger, the plates arranged adjacent to each other may be inverted with respect to each other, i.e. the asymmetric peaks of one plate become the asymmetric valleys of the adjacent plate. So that the asymmetric crests and asymmetric troughs of each plate are arranged adjacently, thereby further improving the strength of the heat exchanger.

The peaks and valleys may have asymmetric shapes. Alternatively, only the peaks may have an asymmetric shape, while the valleys have a symmetric shape; alternatively, only the valleys may have an asymmetric shape, while the peaks have a symmetric shape.

The peaks and/or valleys may define different curvatures on opposite sides of the centerline in cross-section.

According to this embodiment, the asymmetry of the crests and/or troughs is in terms of the curvature of the sheet in the region near the apex of the crests and/or troughs (i.e. the curvature in the cross-section of the sheet of material following the path in the region of the apex). For example, the radius of curvature of the sheet material may vary from one side of the centerline to the other side of the centerline.

Alternatively or additionally, a distance along a surface of the plate between an apex of a peak and an apex of an adjacent first valley may be different than a distance along the surface of the plate between an apex of a peak and an apex of an adjacent second valley.

In a corrugated pattern, the peaks and valleys are arranged alternately, i.e. one given peak is arranged between two valleys, one given valley is arranged between two peaks, with the exception of the peaks or valleys arranged at the outer boundary of the corrugated pattern. Such a peak/valley will have only one adjacent valley/peak.

The sheet material connects the apexes of the crests and troughs (i.e., adjacent crests and troughs) positioned adjacent to each other. According to this embodiment, the asymmetry of a given peak is in the form of a difference in distance along the surface of the sheet to an adjacent valley arranged adjacent the peak on the opposite side of the centre line from the apex of the peak. The difference in distance may for example be caused by a difference in slope of the various portions of the plate.

It should be noted that although the above embodiments refer to the distance between the apex of a peak and the respective apex of an adjacent or neighbouring valley, the above description also applies to the opposite case, i.e. the distance between the apex of a valley and the respective apex of an adjacent or neighbouring peak.

The peaks and valleys may form a herringbone pattern on the plate. According to this embodiment, the peaks and valleys have their apexes extending along a substantially straight line along the surface of the plate and lines formed on the opposite halves that form an angle with respect to each other. When stacking the plates to form a plate heat exchanger, the plates may be arranged in such a way that adjacent plates are upside down with respect to each other. Thus, the lines defined by the herringbone patterns on adjacent plates will not coincide, but cross each other at a plurality of crossing points. The fluid flowing through the flow path defined between the plates by the corrugations is thereby forced to change direction, causing turbulence in the fluid, which provides improved heat transfer.

The asymmetry of a given peak and/or valley may vary along the direction in which the peak and/or valley extends.

According to this embodiment, the asymmetry of the peaks and/or valleys is not constant along the direction in which the respective peak and/or valley extends. The variation in asymmetry may for example be in terms of the magnitude of the asymmetry, i.e. how much the shape of a peak or valley at one side of the centre line which intersects the apex differs from the shape of a peak or valley at the opposite second side of the centre line.

Further, the asymmetric shape may move from one side of the centerline to the other. For example, where the asymmetry defines different curvatures on opposite sides of the centerline, at a given location along the direction in which the peaks or valleys extend, a first radius of curvature R1 may be defined at a first side of the centerline and a second radius of curvature R2 may be defined at an opposite second side of the centerline. However, at another location along the direction, a second radius of curvature R2 may be defined at a first side of the centerline and a first radius of curvature R1 may be defined at a second side of the centerline.

The change in asymmetry can be smooth and continuous. Alternatively or additionally, the abrupt change in asymmetry may occur at a particular location along the direction in which the peaks or valleys extend.

Due to the variation of the asymmetry, turbulence in the fluid flowing through the formed flow path is increased, thereby improving heat transfer.

Furthermore, when stacking the plates to form a plate heat exchanger, variations in asymmetry of adjacent plates with respect to each other may be arranged in a manner that increases the strength of the plate heat exchanger. This allows the plates to be manufactured with a lower thickness, or at least without increasing the thickness, without compromising the strength of the heat exchanger. The lower thickness of the plate improves the heat transfer through the plate even further.

Finally, the variation in asymmetry provides better locking or securing of the panel during pressing when manufacturing the panel. So that the plate can be manufactured in a more accurate manner. This in turn results in a more uniform thickness of the plates and, in case the plate heat exchanger is a washer heat exchanger, an improved contact between the plates when the plates are stacked under tension. Similarly, in case the plate heat exchanger is a brazed heat exchanger, the contact between the plates is also improved.

The variation in asymmetry may be periodic. According to this embodiment, the plates can be appropriately stacked in such a manner as to ensure contact of specific portions of the crests or troughs of adjacent plates.

According to a second aspect of the invention, there is provided a plate heat exchanger comprising a plurality of plates according to the first aspect of the invention arranged in a stacked configuration, wherein peaks and valleys formed in the plates define flow paths between the plates.

Since the plate heat exchanger comprises a plurality of plates according to the first aspect of the invention, the description set forth above with reference to the first aspect of the invention applies here as well.

In particular, in case the asymmetry of the peaks and/or valleys varies in the direction in which the peaks and/or valleys extend, the plates may be stacked in the above-described manner, thereby increasing the strength of the heat exchanger and improving the heat transfer.

Drawings

The invention will now be described in more detail with reference to the accompanying drawings, in which,

figure 1 is a perspective view of a plate heat exchanger according to an embodiment of the invention,

figure 2 shows four plates of a plate heat exchanger according to an embodiment of the invention,

figure 3 is a partial cross-sectional view of a portion of a plate for a plate heat exchanger according to an embodiment of the invention,

figure 4 is a perspective view of a part of a plate for a plate heat exchanger according to an embodiment of the invention,

fig. 5 is a top view of the plate for a plate heat exchanger of fig. 4, and

fig. 6 is a schematic view of a plate for a plate heat exchanger according to an embodiment of the invention.

Detailed Description

Fig. 1 is a perspective view of a plate heat exchanger 1 according to an embodiment of the invention. The plate heat exchanger 1 comprises a plurality of plates 2 arranged in a stack between two end plates 3. The first fluid inlet 4 is connectable to a source of a first heat exchange fluid and the second fluid inlet 5 is connectable to a source of a second heat exchange fluid. The heat exchange fluid thus enters the plate heat exchanger 1 through the

respective fluid inlets

4, 5 and passes along the opposite sides of the respective plate 2 while exchanging heat through the plate 2. The first heat exchange fluid leaves the plate heat exchanger 1 through a first fluid outlet 6 and the second heat exchange fluid leaves the plate heat exchanger 1 through a second fluid outlet 7.

Fig. 2 shows four plates 2 for a plate heat exchanger, such as the one shown in fig. 1. The plates 2 are shown in an exploded manner, i.e. with a distance between the plates 2. However, in order to form a plate heat exchanger by means of the plates 2, the plates 2 are stacked, i.e. arranged next to each other and their surfaces completely overlap. Thus, the

fluid inlets

4, 5 and the

fluid outlets

6, 7 are also arranged adjacent to each other, thereby forming inlet and outlet manifolds for distributing the heat exchange fluid to the flow paths formed between the plates 2.

Each plate 2 is provided with a plurality of corrugations 8, which corrugations 8 define peaks and valleys arranged in a herringbone pattern on the plate 2. The herringbone pattern is arranged in such a way that: i.e. alternating their direction from one plate 2 to the plate 2 arranged adjacent to it. At the location where the peaks of adjacent panels 2 coincide, the panels 2 abut each other. Defining flow paths along the surface of the plates 2 and which ensure the introduction of turbulence in the fluid flowing therein, thus ensuring good heat exchange between the heat exchange fluids flowing along the opposite sides of a given plate 2.

Fig. 3 is a partial cross-sectional view of a part of a plate 2 for a plate heat exchanger according to an embodiment of the invention. The plate 2 is provided with a corrugated pattern 8, which corrugated pattern 8 defines a plurality of peaks 9 and valleys 10. In fig. 3, two peaks 9 and two valleys 10 are shown. A first heat exchange fluid may pass along a first surface of the plate 2 in the cavities defined by the peaks 9 and a second heat exchange fluid may pass along an opposite second surface of the plate 2 in the cavities defined by the valleys 10. The peaks 9 and valleys 10 of the corrugation pattern 8 thus define flow paths along the surface of the plate 2 and heat can be exchanged between the first and second heat exchange fluids through the plate 2.

The crest 9 has an asymmetrical shape with respect to a center line 11 intersecting the apex of the crest 9, which means that the curvature radius R1 of the portion of the crest 9 disposed on the left side of the center line 11 is smaller than the curvature radius R2 of the portion of the crest 9 disposed on the right side of the center line 11. This further results in the distances along the surface of the plate 2 from the apex of a peak 9 to the apex of each adjacent valley 10 being different from one another. Therefore, the distance from the apex of the peak 9 to the apex of the valley 10 disposed on the left side of the peak 9 is shorter than the distance from the apex of the peak 9 to the apex of the valley 10 disposed on the right side of the peak 9.

Furthermore, the valleys 10 also have an asymmetrical shape with respect to the center line 12 intersecting the apexes of the valleys 10, that is, the distances from the apexes of the adjacent peaks 9 are different from each other, similarly to the case described above. Furthermore, the valleys 10 define a radius of curvature R3 that is different from the radii of curvature R1 and R2 defined by the peaks 9.

Due to the asymmetric shape of the peaks 9 and valleys 10, the flow paths defined by the peaks 9 and valleys 10 are also asymmetric, being different from each other along the respective opposite sides of the plate 2. Thus, the pressure conditions prevailing in the first and second heat exchange fluids flowing along the opposite sides of the plates 2 are also different from each other, allowing to obtain the desired heat transfer between the fluids.

Fig. 4 is a perspective view of a part of a plate 2 for a plate heat exchanger according to an embodiment of the invention. The plate 2 of fig. 4 may be, for example, the plate 2 shown in fig. 3.

In the plate 2 shown in fig. 4, the asymmetry of the peaks 9 and valleys 10 is not constant along the direction indicated by the arrow 13 along which the peaks 9 and valleys 10 extend. Instead, the asymmetry shifts from side to side, defining the shoulder 14. The transfer may, for example, cause the radii of curvature R1 and R2 to change position, i.e. the first radius of curvature R1 moves from the left side of the centre line to the right side of the centre line and back again, while the second radius of curvature R2 moves from the right side of the centre line to the left side of the centre line and back again. The variation of the asymmetry along the direction 13 is substantially periodic.

These changes of asymmetry along direction 13 force the heat exchange fluid flowing along the respective flow paths of the surface of plate 2 to change direction, resulting in increased turbulence in the heat exchange fluid. Thereby improving heat transfer between the fluids.

Furthermore, when a plate 2 is stacked with other plates to form a plate heat exchanger, variations in asymmetry of adjacent plates 2 may be arranged relative to each other in a manner that improves the strength of the plate heat exchanger. This allows the plate 2 to be manufactured with a lower thickness without compromising the strength of the plate heat exchanger. The lower thickness of the plate 2 improves the heat transfer through the plate 2 even further.

Finally, the variation in asymmetry provides better locking or securing of the plate 2 during pressing when manufacturing the plate 2. So that the plate 2 can be manufactured in a more accurate manner. This in turn makes the thickness of the plates 2 more uniform and improves the contact between the plates 2 when the plates 2 are stacked under tension.

Fig. 5 is a top view of the plate 2 of fig. 4. Only a portion of the plate 2 is shown. It can be clearly seen how shoulder 14 shifts from side to side along direction 13 in which peak 9 extends. It can also be seen that the shoulder 14 gives the formed flow path along the plate 2 a curved shape, which forces the heat exchange fluid flowing therein to change direction, thereby increasing turbulence in the fluid.

Fig. 6 is a schematic view of a plate 2 for a plate heat exchanger according to an embodiment of the invention. The plate 2 is provided with a plurality of corrugations 8, which corrugations 8 define a plurality of peaks 9 and valleys 10 forming a herringbone pattern.

It can be seen that peaks 9 form shoulders 14 in the manner described hereinbefore with reference to figure 4. Thus, the asymmetry of the peaks 9 varies along the direction in which the peaks 9 extend.

Claims

1. A plate (2) for a plate heat exchanger (1), the plate (2) being provided with a plurality of corrugations (8), a cross-section of the plate (2) thereby defining a plurality of peaks (9) and valleys (10), the plurality of peaks (9) and valleys (10) defining a flow path along a surface of the plate (2), wherein the peaks (9) and/or valleys (10) have a shape that is asymmetric with respect to a centre line (11, 12) that intersects an apex of the peaks (9) and/or valleys (10).

2. The plate (2) for a plate heat exchanger (1) according to claim 1, wherein the peaks (9) and the valleys (10) have an asymmetrical shape.

3. A plate (2) for a plate heat exchanger (1) according to claim 1 or 2, wherein the cross-sections of the peaks (9) and/or valleys (10) define different curvatures on opposite sides of the centre line (11, 12).

4. The plate (2) for a plate heat exchanger (1) according to any of the preceding claims, wherein the distance along the surface of the plate (2) between the apex of the peak (9) and the apex of an adjacent first valley (10) is different from the distance along the surface of the plate (2) between the apex of the peak (9) and the apex of an adjacent second valley (10).

5. The plate (2) for a plate heat exchanger (1) according to any of the preceding claims, wherein the peaks (9) and valleys (10) form a herringbone pattern on the plate (2).

6. The plate (2) for a plate heat exchanger (1) according to any of the preceding claims, wherein the asymmetry of a given peak (9) and/or valley (10) varies along the direction (13) in which the peak (9) and/or valley (10) extends.

7. A plate (2) for a plate heat exchanger (1) according to claim 6, wherein the variation of the asymmetry is periodic.

8. A plate heat exchanger (1) comprising a plurality of plates (2) according to any of the preceding claims arranged in a stacked configuration, wherein peaks (9) and valleys (10) formed in the plates (2) define flow paths between the plates (2).