Brazed plate heat exchanger

Abstract

The brazed plate heat exchanger (10) includes a plurality of heat exchanger plates (12A, 12B) stacked on top of each other. The heat exchanger plates (12A, 12B) are obtained by forming from respective metal sheets and are permanently joined to each other through brazing with a brazing material so as to form a plate package (30) provided with a first plate gap for a first fluid and a second plate gap for a second fluid. The plate package (30) includes an alternating arrangement between a first heat exchanger plate (12A) and a second heat exchanger plate (12B). Each first heat exchanger plate (12A) and each second heat exchanger plate (12B) are provided with a plurality of round holes (P1, P2, P3, P4) and have a generally rectangular shape having two long side edges (26), two short side edges (28), and a longitudinal axis (X) extending parallel to the long side edge (26) and across the short side edge (28). Each first heat exchanger plate (12A) and each second heat exchanger plate (12B) have a corrugated pattern forming at least one heat transfer region (36, 38; 40) including ridges (32) and grooves (34) parallel to each other such that one ridge (32) of the first heat exchanger plate (12A) abuts a groove (34) of an adjacent one of the second heat exchanger plates (12B) so as to extend along the longitudinal axis (X) and form a plurality of joining regions. Each ridge (32) and each groove (34) of at least one first heat transfer region (36) of each first heat exchanger plate (12A) are inclined by a first angle (α) included between 0° and 30° with respect to the longitudinal axis (X). Each ridge (32) and each groove (34) of at least one heat transfer region (40) of each second heat exchanger plate (12B) are inclined by a second angle (β) included between 90° and 45° with respect to the longitudinal axis (X). At least a part of at least one ridge (32) and at least a part of at least one groove (34) of at least the first heat transfer region (36) of each first heat exchanger plate (12A) extend continuously between opposite edges of the respective heat transfer region (36), and these opposite edges are parallel to the short side edge (28).

Description

Technical Field

[0001] The present invention generally relates to plate heat exchangers, and more particularly to brazed plate heat exchangers in which the heat exchanger plates are provided with an improved corrugated pattern of ridges and grooves that facilitate the discharge of liquid condensate.

Background Art

[0002] A heat exchanger is a device used to transfer heat between two or more fluids. A plate heat exchanger is a specific type of heat exchanger in which metal plates are used to transfer heat between two fluids. A plate-type heat exchanger includes a starting plate, an end plate, and a plurality of intermediate plates stacked on top of each other so as to form flow channels therebetween. In a plate-type heat exchanger, two fluids at different temperatures (one is usually identified as a refrigerant fluid) flow through the plate flow channels obtained between the opposing surfaces of a pair of adjacent heat exchanger plates, respectively. In this way, the two fluids exchange their heat quantities. These fluids can flow in countercurrent or cocurrent, and their leak-free circulation is ensured by gaskets or by the joints between the heat exchanger plates.

[0003] The flow channels between the heat exchanger plates are generally obtained by providing a corrugated pattern on both plate surfaces. In other words, both plate surfaces are provided with a press pattern of ridges and grooves. When the heat exchanger plates are stacked on top of each other, the ridges of the first heat exchanger plate contact the grooves of the adjacent heat exchanger plate, and thus these plates are kept separated from each other through spacer elements. In this way, flow channels are formed.

[0004] A common method of manufacturing a plate-type heat exchanger is to brazeweld the heat exchanger plates to each other. This manufacturing method requires that a brazing material be provided to the heat exchanger plates. During manufacturing, the heat exchanger plates are stacked on top of each other and placed in a furnace having a temperature high enough to at least partially melt the brazing material. After the temperature of the furnace has dropped, the brazing material solidifies, enabling the heat exchanger plates to be joined to each other to form a compact and strong heat exchanger.

[0005] The brazed plate heat exchanger, also known by the acronym "BHE", can be used as a condenser for various applications (e.g., air conditioners, heat pumps, etc.). The condensation process is usually carried out in the vertical flow channels of the heat exchanger plates, and the refrigerant vapor generally flows from the top to the bottom of the flow channels according to gravity. This facilitates the discharge of the liquid condensate by gravity and reduces the liquid film thickness on the surface of the plates and its associated thermal resistance.

[0006] Typically, a BHE used as a condenser is installed in a vertical position. This means that since the heat exchanger plates usually have a substantially rectangular shape, the short sides of these plates are arranged horizontally and the long sides of these plates are arranged vertically. Several corrugation patterns of BHE plates are known in the prior art. For example, known corrugation patterns provide a plurality of flow channels in the shape of single or multiple chevron patterns, with one or more vertical fins extending between the short sides of each heat exchanger plate. Further known corrugation patterns are disclosed, for example, in WO 2021 / 154152 pamphlet, EP 3832243 specification, US 7669643 specification, US 2011 / 0083833 application specification, CN 102519281 specification, and JP 11037677 specification.

[0007] The applicant has found that by tilting a BHE provided with a plate having a known waveform pattern at a predetermined angle with respect to the vertical axis, the performance of the BHE condenser is improved at a specific tilt angle (see attached FIGS. 7 and 8). A possible explanation is that a BHE unit tilted at a specific angle that seems to be related to the cross-waveform angle and the direction of gravity allows for the final improvement of the condensation process (lower condensation temperature or lower temperature approach), while facilitating the discharge of the liquid condensate to the bottom of the heat exchanger plate (where subcooled liquid accumulates), thinning the liquid film, and thus reducing its thermal resistance. Therefore, since it is inconvenient to install these BHE units in non-vertical arrangements, there is a need to improve such prior art BHE units.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0009] Therefore, one object of the present invention is to provide a brazed plate heat exchanger that can solve the drawbacks of the prior art in a simple, inexpensive, and particularly functional manner.

[0010] Specifically, one object of the present invention is to provide a brazed plate heat exchanger that can discharge liquid condensate from the bottom of the heat exchanger plate more easily and quickly than a brazed plate heat exchanger according to the prior art, and can ensure good heat transfer by an appropriate and special selection of the waveform angle of the plate.

[0011] Another object of the present invention is to provide a brazed plate heat exchanger in which the waveform pattern of the heat exchanger plate is easier to manufacture than a brazed plate heat exchanger according to the prior art.

Means for Solving the Problems

[0012] These objects are achieved according to the present invention by providing a brazed plate heat exchanger as defined in the appended claims.

[0013] Further features of the present invention are emphasized by the dependent claims, which are an essential part of this specification.

[0014] The brazed plate heat exchanger according to the present invention includes a plurality of heat exchanger plates stacked on top of each other. The heat exchanger plates are obtained by forming from respective metal sheets. The heat exchanger plates are permanently joined to each other through brazing with a brazing material so as to form a plate package provided with a first plate gap for a first fluid and a second plate gap for a second fluid. The plate package includes an alternating arrangement between a first heat exchanger plate and a second heat exchanger plate. Each between the first heat exchanger plate and the second heat exchanger plate is provided with a plurality of round holes and has a substantially rectangular shape having two long side edges, two short side edges, and a longitudinal axis extending parallel to the two long side edges and across the two short side edges. Each between the first heat exchanger plate and the second heat exchanger plate has a corrugated pattern forming at least one heat transfer region extending along the longitudinal axis. Each heat transfer region includes ridges and grooves parallel to each other arranged such that one ridge of one of the first heat exchanger plates abuts against the groove of an adjacent one of the second heat exchanger plates so as to form a plurality of joining regions.

[0015] Each ridge and each groove of at least one first heat transfer region of each first heat exchanger plate are inclined by a first angle included between 0° and 30° with respect to the longitudinal axis. In addition, each ridge and each groove of at least one heat transfer region of each second heat exchanger plate are inclined by a second angle included between 90° and 45° with respect to the longitudinal axis. Finally, at least a part of the ridges and at least a part of the grooves of at least the first heat transfer region of each first heat exchanger plate extend continuously between the opposing edges of the respective heat transfer regions, and these opposing edges are parallel to the short side edges.

[0016] Preferably, the first angle is 20° and the second angle is 70°.

[0017] Also preferably, the number of ridges, and thus the number of grooves, in the first heat transfer region of each first heat exchanger plate that extends continuously between the opposing edges of each heat transfer region is equal to at least 30% of the total number of ridges, and thus the total number of grooves, in the first heat transfer region of each first heat exchanger plate.

[0018] According to a preferred embodiment of the present invention, each of the first heat exchanger plates is provided with at least one second heat transfer region adjacent to the first heat transfer region. Each ridge and each groove of the second heat transfer region are preferably inclined by a third angle included between 45° and 90° with respect to the longitudinal axis. More preferably, this third angle is 65°.

[0019] Also preferably, at least a part of the ridges and at least a part of the grooves of the second heat transfer region extend seamlessly, that is, continuously, between the opposing edges of each second heat transfer region, and these opposing edges are parallel to the short side edges. More preferably, the second heat transfer region has a longitudinal extension equal to about 1 / 3 of the longitudinal extension of the first heat transfer region measured along the longitudinal axis.

[0020] Each ridge and each groove of each heat transfer region of both the first heat exchanger plate and the second heat exchanger plate are preferably linear and continuous along each heat transfer region. The longitudinal axis is preferably a vertical axis.

[0021] According to a preferred embodiment, four round holes are provided between each of the first heat exchanger plate and the second heat exchanger plate. The round holes are then arranged at each corner of each heat exchanger plate, that is, at the contact points between the long side edge and the short side edge of each heat exchanger plate.

[0022] Preferably, at least one of the round holes can be arranged at a distance from its nearest long side edge that is different from the distances of each of the remaining round holes from their respective nearest long side edges. More preferably, the distance of at least one round hole is longer than the distances of the remaining round holes. Even more preferably, each corner of each heat exchanger plate is rounded.

[0023] The features and advantages of the brazed plate heat exchanger according to the present invention will become more apparent from the following illustrative and non - limiting description with reference to the accompanying schematic drawings.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Best Mode for Carrying Out the Invention

[0025] Referring to FIGS. 1 and 2, a brazed plate heat exchanger 10 is shown. The heat exchanger 10 includes a plurality of heat exchanger plates 12A, 12B stacked on top of each other in a manner known per se. Typically, the heat exchanger plates 12A, 12B are stacked on top of each other between a first end plate 14 and a second end plate 16 of the heat exchanger 10. Each heat exchanger plate 12A, 12B is obtained by forming from a respective metal sheet. The first end plate 14, the second end plate 16, and the heat exchanger plates 12A, 12B are permanently joined to each other through brazing with a brazing material so as to form a plate package 30. Accordingly, the plate package 30 is provided with a first plate gap for a first fluid and a second plate gap for a second fluid. The first fluid and the second fluid can be any suitable heat transfer fluid.

[0026] The plate package 30 of the heat exchanger 10 includes an alternating arrangement between a first heat exchanger plate 12A and a second heat exchanger plate 12B. In other words, starting from the first end plate 14 to the second end plate 16, the first heat exchanger plate 12A is joined to the second heat exchanger plate 12B, the second heat exchanger plate 12B is joined to another first heat exchanger plate 12A, and so on. Accordingly, the plate gaps are obtained between different types of heat exchanger plates 12A, 12B, namely, between the first heat exchanger plate 12A and the second heat exchanger plate 12B.

[0027] Between the first heat exchanger plate 12A and the second heat exchanger plate 12B, and between the first end plate 14 and the second end plate 16 respectively, a plurality of round holes, preferably four round holes P1, P2, P3, and P4 are provided. The first round hole P1 is connected to the first connecting pipe 18 and communicates with the first plate gap. The second round hole P2 is connected to the second connecting pipe 20 and communicates with the first plate gap. The third round hole P3 is connected to the third connecting pipe 22 and communicates with the second plate gap. Finally, the fourth round hole P4 is connected to the fourth connecting pipe 24 and communicates with the second plate gap. The connecting pipes 18, 20, 22, and 24 may extend from the first end plate 14 and / or from the second end plate 16 as shown in FIG. 1.

[0028] Each of the spaces between the first heat exchanger plate 12A and the second heat exchanger plate 12B, and between the first end plate 14 and the second end plate 16 has a generally rectangular shape with two long sides 26 and two short sides 28, as shown in FIG. 2. The longitudinal axis X extends parallel to the two long sides 26 and across the two short sides 28.

[0029] Each of the spaces between the first heat exchanger plate 12A and the second heat exchanger plate 12B has a corrugated pattern forming at least one heat transfer region 36, 38, 40 extending along the longitudinal axis X. Each heat transfer region 36, 38, 40 includes ridges 32 and grooves 34 parallel to each other, arranged such that one ridge 32 of the first heat exchanger plate 12A abuts against an adjacent groove 34 of the second heat exchanger plate 12B to form a plurality of small joining regions (referred to as brazed joints).

[0030] According to the present invention, each rib 32 of at least one first heat transfer region 36 of each first heat exchanger plate 12A, and thus each groove 34, is inclined by a first angle α included between 0° and 30° with respect to the longitudinal axis X, as shown in FIG. 3. Each rib 32 of the heat transfer region 40 of each second heat exchanger plate 12B, and thus each groove 34, is instead inclined by a second angle β between 90° and 45° with respect to the longitudinal axis X, as shown in FIG. 5. Preferably, the first angle α is 20° and the second angle β is 70°.

[0031] In addition, at least a part of the ribs 32 of the first heat transfer region 36 of each first heat exchanger plate 12A, and thus at least a part of the grooves 34, extend continuously between the opposing edges of the respective heat transfer regions 36, that is, between the opposing edges parallel to the short side edges 28 of each first heat exchanger plate 12A. In other words, since the longitudinal axis X is preferably a vertical axis, as shown, at least a part of the ribs 32 of the first heat transfer region 36 of each first heat exchanger plate 12A, and thus at least a part of the grooves 34, extend seamlessly, that is, continuously, from the top to the bottom of the respective heat transfer regions 36.

[0032] Preferably, the number of ribs 32, and thus grooves 34, of the first heat transfer region 36 of each first heat exchanger plate 12A that extend continuously between the opposing edges of the respective heat transfer regions 36 is equal to at least 30% of the total number of ribs 32, and thus grooves 34, of the first heat transfer region 36 of each first heat exchanger plate 12A. For example, a suitable first angle α of 20° for each first heat exchanger plate 12A ensures that at least 40% of each rib 32, and thus each groove 34, extends seamlessly from the top to the bottom of the first heat transfer region 36 of each first heat exchanger plate 12A.

[0033] The second angle β of the second heat exchanger plate 12B, which is included between 90° and 60°, preferably equal to 70°, is selected so as to obtain a good heat transfer coefficient. In fact, in heat exchanger plates according to the prior art having a standard pattern, i.e., a small corrugation angle (e.g., 20°), two drawbacks occur with respect to pairs of adjacent heat exchanger plates, namely a low heat transfer coefficient and an inaccurate distribution of the fluid within each flow path.

[0034] Preferably, as shown in FIG. 3, each first heat exchanger plate 12A is provided with at least one second heat transfer region 38 adjacent to the first heat transfer region 36. More specifically, when the longitudinal axis X is the vertical axis, the second heat transfer region 38 is arranged below the first heat transfer region 36. Each ridge 32 of this second heat transfer region 38, and thus each groove 34, is inclined by a third angle γ included between 45° and 90° with respect to the longitudinal axis X. Preferably, the third angle γ is 65°.

[0035] Similar to the first heat transfer region 36, at least a part of the ridges 32 of the second heat transfer region 38, and thus at least a part of the grooves 34, preferably extend continuously between the opposing edges of each second heat transfer region 38, i.e., between the opposing edges parallel to the short side edges 28 of each first heat exchanger plate 12A. Preferably, as shown in FIG. 3, the second heat transfer region 38 of each first heat exchanger plate 12A has a longitudinal extension equal to approximately 1 / 3 of the longitudinal extension of the first heat transfer region 36 of each first heat exchanger plate 12A measured along the longitudinal axis X.

[0036] The above-described corrugation patterns of both the first heat exchanger plate 12A and the second heat exchanger plate 12B are schematically shown in FIG. 10. This corrugation pattern enables one of the fluids processed by the heat exchanger 10, for example, the liquid condensate when the heat exchanger 10 is used as a condenser, to move along a substantially vertical gap so as to be easily reached by the bottom zones of the heat exchanger plates 12A, 12B. In addition, this advantageous feature is reinforced by the fact that each ridge 32 and each groove 34 of each heat transfer region 36, 38, 40 of both the first heat exchanger plate 12A and the second heat exchanger plate 12B are linear and continuous along their respective heat transfer regions 36, 38, 40. In other words, no vertical spikes or other discontinuities are provided in the heat exchanger plates 12A, 12B in their respective heat transfer regions 36, 38, 40, and thus the ability of the liquid condensate to easily reach the bottom zones of the heat exchanger plates 12A, 12B is improved.

[0037] Preferably, each of the four round holes P1, P2, P3, P4 of the heat exchanger plates 12A, 12B is disposed at each corner of the respective heat exchanger plates 12A, 12B. In other words, as shown, each of the four round holes P1, P2, P3, P4 of the heat exchanger plates 12A, 12B is disposed at the contact point between the long side edge 26 and the short side edge 28 of the respective heat exchanger plates 12A, 12B. More preferably, each corner of each heat exchanger plate 12A, 12B is rounded.

[0038] According to a preferred embodiment of the present invention, at least one of the round holes P4 in each of the heat exchanger plates 12A and 12B, that is, the upper left round hole P4 in FIGS. 3 and 5, is arranged at a distance D1 from the nearest long side edge 26, which is different from the distances D2 and D3 from the nearest long side edge 26 of each of the remaining round holes P1, P2, and P3. Preferably, but not exclusively, the distance D1 of the at least one round hole P4 is longer than the distances D2 and D3 of the remaining round holes P1, P2, and P3. This preferred technical feature is due to the fact that a specific innovative combination of the corrugation angles α and β requires an equally specific fluid port arrangement in order to have a uniform fluid distribution along the width of the heat exchanger plates 12A and 12B (so as to maximize heat transfer).

[0039] Thus, it can be seen that the brazed plate heat exchanger according to the present invention achieves the object outlined above.

[0040] The brazed plate heat exchanger of the present invention thus devised is admissible in any case of numerous refinements and variations, all of which are included in the same inventive concept. In addition, all details can be replaced by technically equivalent elements. In practice, the materials used, as well as the shape and size, can be of any type according to the technical requirements.

[0041] Therefore, the protection scope of the present invention is defined by the appended claims.

Description of Reference Numerals

[0042] 10 Heat exchanger 12A First heat exchanger plate 12B Second heat exchanger plate 14 First end plate 16 Second end plate 18 First connection pipe 20 Second connection pipe 22 Third connection pipe 24 Fourth connection pipe 26 Plate long side edge 28 Plate short side edge 30 Plate package 32 Protrusion 34 Groove 36 First heat transfer region of the first heat exchanger plate 38 Second heat transfer region of the first heat exchanger plate 40 Heat transfer region of the second heat exchanger plate α First angle β Second angle γ Third angle P1 First round hole P2 Second round hole P3 Third round hole P4 Fourth round hole D1 Distance between the fourth round hole and each plate long side edge D2 Distance between the first and third round holes and each plate long side edge D3 Distance between the second round hole and each plate long side edge

Claims

1. A brazed plate heat exchanger (10) including a plurality of heat exchanger plates (12A, 12B) stacked on one another, wherein the heat exchanger plates (12A, 12B) are obtained by forming from respective metal sheets, and the heat exchanger plates (12A, 12B) are permanently joined to one another through brazing with a brazing material so as to form a plate package (30) provided with a first plate gap for a first fluid and a second plate gap for a second fluid. The plate package (30) includes an alternating arrangement between a first heat exchanger plate (12A) and a second heat exchanger plate (12B). Each between the first heat exchanger plate (12A) and the second heat exchanger plate (12B) is provided with a plurality of round holes (P1, P2, P3, P4), and has a substantially rectangular shape having two long side edges (26), two short side edges (28), and a longitudinal axis (X) extending parallel to the two long side edges (26) and crossing the two short side edges (28). Each between the first heat exchanger plate (12A) and the second heat exchanger plate (12B) has a corrugated pattern forming at least one heat transfer region (36, 38; 40) extending along the longitudinal axis (X). Each heat transfer region (36, 38; 40) includes ridges (32) and grooves (34) parallel to each other arranged such that one ridge (32) of the first heat exchanger plate (12A) abuts against a groove (34) of an adjacent one of the second heat exchanger plates (12B) so as to form a plurality of joining regions. The brazed plate heat exchanger (10) is each ridge (32) and each groove (34) of at least one first heat transfer region (36) of the first heat exchanger plate (12A) is inclined by a first angle (α) included between 0° and 30° with respect to the longitudinal axis (X); each ridge (32) and each groove (34) of at least one heat transfer region (40) of the second heat exchanger plate (12B) is inclined by a second angle (β) included between 90° and 45° with respect to the longitudinal axis (X). At least a part of the raised portions (32) and at least a part of the grooves (34) in at least the first heat transfer region (36) of the first heat exchanger plate (12A) extend continuously between the opposing edges of the respective heat transfer regions (36), and the opposing edges are parallel to the short side edges (28). The brazed plate heat exchanger (10), characterized in that. **Claim 2** The brazed plate heat exchanger (10) according to claim 1, characterized in that the first angle (α) is 20°. **Claim 3** The brazed plate heat exchanger (10) according to claim 1 or 2, characterized in that the second angle (β) is 70°. **Claim 4** The number of the raised portions (32), and thus the grooves (34), of the first heat transfer region (36) of each first heat exchanger plate (12A) that extend continuously between the opposing edges of the respective heat transfer regions (36) is equal to at least 30% of the total number of the raised portions (32), and thus the grooves (34), of the first heat transfer region (36) of the first heat exchanger plate (12A). The brazed plate heat exchanger (10) according to any one of claims 1 to 3, characterized in that. **Claim 5** The brazed plate heat exchanger (10) according to any one of claims 1 to 4, characterized in that each of the first heat exchanger plates (12A) is provided with at least one second heat transfer region (38) adjacent to the first heat transfer region (36). **Claim 6** The brazed plate heat exchanger (10) according to claim 5, characterized in that each raised portion (32) and each groove (34) of the second heat transfer region (38) are inclined by a third angle (γ) included between 45° and 90° with respect to the longitudinal axis (X). **Claim 7** The brazed plate heat exchanger (10) according to claim 6, characterized in that the third angle (γ) is 65°. **Claim 8** The brazed plate heat exchanger (10) according to any one of claims 5 to 7, characterized in that at least a part of the raised portions (32) and at least a part of the grooves (34) of the second heat transfer region (38) extend seamlessly, that is, continuously, between the opposing edges of the respective second heat transfer regions (38), and the opposing edges are parallel to the short side edges (28). **Claim 9** The brazed plate heat exchanger (10) according to any one of claims 5 to 8, characterized in that the second heat transfer region (38) has a longitudinal extension equal to about 1 / 3 of the longitudinal extension of the first heat transfer region (36) measured along the longitudinal axis (X).

10. The brazed plate heat exchanger (10) according to any one of claims 1 to 9, characterized in that each raised portion (32) and each groove (34) of each heat transfer region (36, 38; 40) of the first heat exchanger plate (12A) and the second heat exchanger plate (12B) are linear and continuous along the respective heat transfer regions (36, 38; 40).

11. The brazed plate heat exchanger (10) according to any one of claims 1 to 10, characterized in that the longitudinal axis (X) is a vertical axis.

12. Four round holes (P1, P2, P3, P4) are provided between the first heat exchanger plate (12A) and the second heat exchanger plate (12B), and each round hole (P1, P2, P3, P4) is at each corner of the respective heat exchanger plate (12A, 12B), that is, at the contact point between the long side edge (26) and the short side edge (28) of the respective heat exchanger plate (12A, 12B). The brazed plate heat exchanger (10) according to any one of claims 1 to 11, characterized in that it is arranged.

13. The brazed plate heat exchanger (10) according to any one of claims 1 to 12, characterized in that at least one of the round holes (P4) is arranged at a distance (D1) from the nearest long side edge (26) different from the distances (D2, D3) from the nearest long side edge (26) of the remaining round holes (P1, P2, P3).

14. The brazed plate heat exchanger (10) according to claim 13, characterized in that the distance (D1) of the at least one round hole (P4) is longer than the distances (D2, D3) of the remaining round holes (P1, P2, P3).

15. The brazed plate heat exchanger (10) according to any one of claims 12 to 14, characterized in that each corner of each heat exchanger plate (12A, 12B) is rounded.

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