Plate heat exchanger comprising shaped guide elements

Abstract

A plate heat exchanger (1) between a first fluid intended to circulate along a first direction (X) and a second fluid intended to circulate along a second direction (Y) different from the first direction, the heat exchanger comprising stacked stages (2, 3) for the circulation of the first fluid and shaped elements (10) at the inlet and outlet of the stages, the shaped elements (10) having a sawtooth cross section and defining converging channels at the inlet of the stages and diverging channels at the outlet of the stages is disclosed, in particular for an aircraft turbine.

Description

Technical Field

[0001] This invention relates to a heat exchanger, particularly a heat exchanger for turbines. Background Technology

[0002] The technical background specifically includes documents US-A1-2019 / 285349, FR-A1-3 077 630, DE-A1-199 43389, FR-A1-918 616, DE-A1-196 44 711 and GB-A-634 608.

[0003] Typically, turbines, particularly those used in aircraft, comprise, from upstream to downstream, at least one compressor, a combustion chamber, at least one turbine, and nozzles in the direction of gas flow. The compressor is configured to increase the pressure of air, which is then delivered to the combustion chamber. In the combustion chamber, the air is mixed with fuel and burned. The combustion gases then pass through the turbine, which drives the compressor by collecting some pressure energy from the gas leaving the combustion chamber and converting that pressure energy into mechanical energy. The nozzles eject exhaust gases to generate propulsion for the turbine.

[0004] A heat exchanger is installed in the turbine so that heat energy can be transferred from one fluid to another.

[0005] For example, heat exchangers can be used to transfer heat from hot exhaust gas to gas upstream that is intended to be introduced into the combustion chamber, which is particularly beneficial for fuel combustion in the turbine. Heat exchangers can also be used to cool lubricants, such as oil, used to guide the rotors of the compressor and turbine, which each consist of a first set of stationary components forming the stator and a second set of components forming the rotor, the second set of components being rotatable relative to the stator.

[0006] For equivalent aerodynamic performance, finned heat exchangers are particularly used in turbines due to their low mass.

[0007] Such a heat exchanger between a first fluid (e.g., hot exhaust gas) and a second fluid (e.g., air) includes a flow stage for the first fluid and a flow path for the second fluid formed between two consecutive flow stages of the first fluid. The flow stage of the first fluid includes, for example, two parallel plates and a series of fins, the two parallel plates being spaced apart to define a flow channel for the first fluid, and the series of fins being arranged, for example, generally perpendicularly between the plates.

[0008] Figure 1 and Figure 2Examples of such heat exchanger 1 and stages 2 and 3 of such heat exchanger are shown respectively. In this heat exchanger 1, a first fluid flows along a longitudinal direction, denoted as X, and a second fluid flows approximately perpendicular to the first fluid along a direction denoted as Y. It should be noted that in other examples of such heat exchangers, the first and second fluids can be arranged to flow in parallel directions relative to each other in the core of the heat exchanger. However, in this case, the directions of the two flows are designed to intersect approximately perpendicularly near the inlet and outlet of the heat exchanger, such that the two flows exit at different surfaces of the heat exchanger.

[0009] Each stage 2, 3 includes two parallel plates 6 spaced apart from each other, which extend longitudinally along direction X to define a flow channel 7 for the first fluid.

[0010] To separate the first fluid within the exchanger 1, each stage 2, 3 further includes two outer partitions 5, which are arranged generally perpendicular to the plate 6 and extend longitudinally in the direction X, such that the plates 5, 6 define a flow channel 7. Each stage 2, 3 also includes a series of fins 9 arranged generally perpendicularly between the plates 6 to define a series of conduits in the flow channel 7.

[0011] The flow path 4 of the second fluid is positioned between the two flow stages 2 and 3 of the first fluid. To separate the second fluid within the exchanger 1, the exchanger 1 includes plates 8 arranged substantially perpendicular to plates 5 and 6 and extending longitudinally in the Y direction, such that plates 6 and 8 define the flow path 4. Rows of fins 9 are arranged substantially perpendicularly between the two flow stages 2 and 3 of the first fluid to define a series of conduits within the flow channel 4.

[0012] However, heat exchanger 1 has a sudden decrease in the cross-sectional area through which the first fluid passes at the inlet of the exchanger, and a sudden increase in the cross-sectional area through which the first fluid passes at the outlet of the exchanger (see...). Figure 2 , Figure 2 The evolution of the outlet of channel 7 and the cross sections S0, S1, and S2 through which the first fluid passes is shown.

[0013] A first fluid is supplied to exchanger 1 via distributor D, which directs the first fluid from flow direction X1, which is approximately perpendicular to direction X, to direction X, so that the first fluid reaches the inlet of flow channel 7. Manifold C directs the first fluid from direction X to flow direction X2, which is approximately perpendicular to direction X. Similarly, a second fluid flowing along direction Y can reach plate 5 and abruptly redirect towards flow path 4.

[0014] Due to the presence of plates 5 and 8 and fins, the cross-section of flow channel 7 and the cross-section of flow path 4 are smaller than the cross-section of the fluid channels in distributor D and manifold C.

[0015] Furthermore, the greater the change in the cross-sectional area of ​​the fluid channel, the greater the sudden decrease in the cross-sectional area of ​​the fluid channel at the inlet of the exchanger and the sudden increase in the cross-sectional area of ​​the fluid channel at the outlet of the exchanger. More specifically, when there is a significant deviation between the height of the cross-sectional area of ​​the first fluid channel and the height of the cross-sectional area of ​​the second fluid channel (i.e., between the height of fin 9 and the height of plates 5 and 8), a sudden decrease in the cross-sectional area of ​​the fluid channel entering the exchanger and a sudden increase in the cross-sectional area of ​​the fluid channel leaving the exchanger may be encountered.

[0016] One of the drawbacks of this type of architecture is that it results in significant energy loss (also known as pressure loss). In particular, this pressure loss can correspond to more than 20% of the total allowable pressure loss.

[0017] Because the region where this pressure loss occurs contributes relatively little to heat exchange, reducing this pressure loss is crucial. Furthermore, high pressure losses can lead to uneven flow distribution, which can degrade exchanger performance. Uncontrolled or unguided flow deflection at the inlet and outlet results in uneven velocity distribution within a given cross-section of distributor D and manifold C.

[0018] Due to the strict limitations on mass when having equivalent thermal performance, the object of the present invention is to provide a heat exchanger with reduced pressure loss, equivalent thermal performance, and equivalent mass.

[0019] In application FR-A1-3 077 630, the applicant has proposed a heat exchanger equipped with forming elements at the inlet and outlet of a flow channel for a first fluid. The applicant proposes improvements to the technology described in that document. Summary of the Invention

[0020] Therefore, the present invention relates to a plate heat exchanger between a first fluid and a second fluid, particularly for use in aircraft turbines, wherein the first fluid is intended to flow along a first direction and the second fluid is intended to flow along a second direction different from the first direction, the exchanger comprising stacked stages for the flow of the first fluid, each stage comprising:

[0021] - Two parallel plates, spaced apart, define a channel between them for the flow of a first fluid.

[0022] A series of fins, arranged substantially vertically at each plate, define a series of conduits for the flow of a first fluid within the flow channels.

[0023] - First forming elements, the first forming elements being used to allow first fluid to enter a flow channel, these first forming elements being located at the inlet of the channel at each of the plates to define a first convergence path for guiding the first fluid into the channel, and / or

[0024] - Second forming elements, which are used for the outlet of the first fluid flowing out of the flow channel, are located at the outlet of the channel at each plate in the plate to define a second expanding path for guiding the first fluid out of the channel.

[0025] The feature is that each of the first and second molded parts has a serrated portion in cross-section, the serrated portion comprising:

[0026] - A first outer peripheral edge, the first outer peripheral edge including a generally straight first end, a second end and a convex curved portion, the generally straight first end being for connection to a plate defining a first flow channel in a flow channel in a plate, the second end being located at the tip of the forming element, and the convex curved portion extending between the first end and the second end.

[0027] - A second outer peripheral edge, comprising a generally straight third end, a fourth end, and a concave curved portion, the generally straight third end being for connection to a plate defining a second flow channel adjacent to the first channel in the flow channel, the fourth end being located at the tip of the forming element and oriented generally perpendicularly to the third end, and forming an angle of less than 90° with the second end, the concave curved portion extending between the third end and the fourth end.

[0028] The concave and convex curved portions of the first and second molded parts have different curvatures to define the first and second paths.

[0029] The objective of this invention is to significantly reduce pressure loss of the first fluid at the inlet and outlet of the flow channel. This is achieved by shaping elements configured to ensure a gradual acceleration of the flow at the inlet and a gradual deceleration of the flow at the outlet. These elements are also configured to introduce a gradual deflection of the flow while gradually changing the cross-sectional area through which the fluid passes to avoid backflow regions in the flow. In particular, this invention enables a significant reduction in pressure loss at constant overall dimensions, improves flow distribution (homogenization), and reduces the volume of the distributors and manifolds of the exchanger at constant load losses (because a 90° deflection is much shorter in terms of flow guidance), which allows for better pressure resistance and reduced mass of the distributors and manifolds. The distributors and manifolds can be integrated into the exchanger or are separate components mounted to the exchanger.

[0030] The heat exchanger according to the invention includes one or more of the following features, which may be used individually or in combination with each other:

[0031] - The second end, located at the tip of the forming element, is oriented approximately perpendicular to the first end;

[0032] - The second end located at the tip of the forming element forms an angle with the first end, the angle being between 60° and 95°, preferably between 70° and 90°;

[0033] - The tips of the first forming element and the second forming element are tapered;

[0034] - The first forming element is carried by a manifold, which is assembled to the inlet of the plate; the second forming element is carried by a distributor, which is assembled to the outlet of the plate.

[0035] - The first forming element and the second forming element are integrated with the plate;

[0036] - The curvature of the convex curved portion corresponds to one-quarter of the following ellipse, which has a larger radius a1 at the second end and a smaller radius b1 at the first end. The curvature of the concave curved portion corresponds to a portion (e.g., one-quarter) of the following ellipse, which has a larger radius a2 at the fourth end and a smaller radius b2 at the third end. The ellipses have the same center, and a2 and b2 are greater than a1 and b1, respectively.

[0037] - All the first forming elements are identical, and all the second forming elements are identical;

[0038] -[Function 1]

[0039] a2=a1+h·R d

[0040] Where h is the distance between the plates, and Rd is a parameter used to control the change in the cross-section of the corresponding path.

[0041] -[Function 2]

[0042]

[0043] [Function 3]

[0044] b1 = b2 - h

[0045] The spacing is the distance between two adjacent flow channels;

[0046] -[Function 4]

[0047] a 1，n+1 =a 1，n +Ra

[0048] Or [Function 5]

[0049] a 1，n+1 =a 1，n ·R g

[0050] Where Ra and Rg are the factors of these sequences, the first sequence is an arithmetic sequence, and the second sequence is a geometric sequence;

[0051] - The fins are arranged roughly vertically between the plates.

[0052] The present invention also relates to a turbine comprising at least one heat exchanger as described above.

[0053] The present invention also relates to a method for manufacturing a heat exchanger according to the invention, the method comprising the step of manufacturing the heat exchanger by additive manufacturing of selective melting on a powder bed.

[0054] Advantageously, the method of manufacturing the heat exchanger according to the invention by additive manufacturing using selective melting on a powder bed is simpler than the method of manufacturing the heat exchanger by brazing. In particular, it is easier to manufacture the heat exchanger according to the invention by additive manufacturing using selective melting on a powder bed than by brazing.

[0055] Furthermore, due to the method used to manufacture the heat exchanger according to the invention, it is not necessarily necessary to have a specific support when manufacturing the heat exchanger. Attached Figure Description

[0056] Other features and advantages of the invention will become apparent from the following detailed description, and with reference to the accompanying drawings, in order to understand it:

[0057] Figure 1 This is a schematic perspective view of a plate heat exchanger used in aircraft turbines.

[0058] Figure 2 This is a schematic diagram of the flow of the first fluid at the outlet of a heat exchanger based on existing technology.

[0059] Figure 3 This is a schematic diagram of the manifold or distributor of the plate heat exchanger according to the present invention.

[0060] Figure 4 yes Figure 3 An enlarged view of a portion of the heat exchanger and showing its shaped components.

[0061] Figures 5a and 5b are schematic diagrams illustrating examples of the curvature of the shaped elements of a heat exchanger.

[0062] Figure 6 Is with Figure 4 A similar view, showing the flow of the first fluid leaving the exchanger, and

[0063] Figure 7 Is with Figure 4 A similar view is shown, illustrating the flow of the first fluid at the inlet of the exchanger. Detailed Implementation

[0064] This invention relates to a heat exchanger 1, examples of which are shown in... Figure 1 As shown and described above, the above description applies to heat exchangers according to the present invention.

[0065] In addition to the features described above, the exchanger 1 according to the invention also includes a shaping element 10 at the inlet and outlet of the channel 7, which is designed to optimize the deflection of the flow of the first fluid while avoiding the occurrence of backflow areas and pressure loss.

[0066] Figure 3 Only a portion of the heat exchanger 1 according to the invention is shown, more specifically the side of the exchanger corresponding here to the manifold C, which serves as the outlet for the first fluid to flow out from the aforementioned channel 7. The following description also applies to the distributor D, which is installed at the inlet of the channels to supply the first fluid to these channels 7.

[0067] As described above, the first fluid is collected by channel 7 in manifold C along direction X and deflected along direction X2. In distributor D, the first fluid flows along direction X1 and is redirected along direction X.

[0068] The forming element 10 may be carried by the manifold D or the distributor D, and may be integrated or integrally formed with, for example, the manifold or the distributor. Alternatively, the forming element 10 may be disposed directly at the end of the plate 6, and thus independently of the manifold C and the distributor D, the plate defining the channel 7 between the plates.

[0069] The forming element 10 is located at the plate 6 and has the function of defining a convergence path on the one hand and a divergence path on the other. The convergence path is used to guide the first fluid to the channel 7 at the inlet, and the divergence path is used to guide the first fluid from the channel 7 at the outlet.

[0070] Each forming element in the forming element 10 is located on a common side of two adjacent plates 6 and extends along that side. One of the plates 6 defines a first channel 7, while the other plate defines an adjacent channel 7. Therefore, each forming element in the forming element 10 has a generally elongated shape. Each forming element in the forming element 10 has a generally serrated portion in cross-section, as shown in... Figure 4 It can be seen more clearly in the middle.

[0071] The serrated part includes:

[0072] - First outer peripheral edge B1, the first outer peripheral edge includes a generally straight first end B11, a second end B12 and a convex curved portion B13, the first end is for connection to a first plate in plate 6 (defining a first flow channel 7), the second end is located at the tip 14 of the forming element 10 and is oriented generally perpendicular to the first end B11, and the convex curved portion extends between the first end B11 and the second end B12.

[0073] - Second outer peripheral edge B2, the second outer peripheral edge includes a generally straight third end B21, a fourth end B22 and a concave curved portion B23, the third end is for connection to a second plate in plate 6 (defining a second flow channel 7 adjacent to the first channel), the fourth end is located at the tip 14 of the forming element 10 and is oriented generally perpendicular to the third end B21, the concave curved portion extends between the third end B21 and the fourth end B22.

[0074] The concave curved portion B23 and the convex curved portion B13 of the formed part 10 have different curvatures to define the aforementioned convergence path and divergence path 12.

[0075] As in Figure 4 As can be seen, the tips 14 of the forming elements 10 are all oriented in the same direction and are tapered, i.e., as thin as possible. The thickness of the forming elements is, for example, less than or equal to 0.5 mm.

[0076] The schematic diagram in Figure 5a shows the difference in curvature between the two portions B13 and B23 of the serrated shape of each forming element 10.

[0077] The curvature of the convex curved portion B13 corresponds to one-quarter or less of the radius of an ellipse E1, which has a larger radius a1 at the second end B12 and a smaller radius b1 at the first end B11.

[0078] The curvature of the concave curved portion B23 corresponds to one-quarter of the ellipse E2, which has a larger radius a2 at the fourth end B23 and a smaller radius b2 at the third end B21.

[0079] As can be seen in Figure 5a, ellipses E1 and E2 have the same center O, and ellipse E2 is larger than ellipse E1, that is, a2 and b2 are larger than a1 and b1, respectively.

[0080] In illustrating the first embodiment of the present invention Figures 3 to 7 In the example shown, the forming elements 10 are all the same.

[0081] The following equations enable the calculation of the values ​​of a1, a2, b1, and b2. The following equations are given as examples.

[0082] [Function 1]

[0083] a2=a1+h·R d

[0084] Where h is the distance between plates 6, and h is therefore the height of channel 7, as shown below. Figure 6 As shown,

[0085] Furthermore, Rd is a parameter that controls the change in the cross-section of the corresponding path 12.

[0086] [Function 2]

[0087]

[0088] [Function 3]

[0089] b1 = b2 - h

[0090] Wherein, the spacing is the distance between two adjacent channels 7, such as Figure 6 As shown.

[0091] Alternatively, the forming element 10 is different and its size is determined according to a predetermined arithmetic or geometric sequence.

[0092] [Function 4]

[0093] a 1，n+1 =a 1，n +R a

[0094] Or [Function 5]

[0095] a 1，n+1 =a 1，n ·R g

[0096] Ra and Rg are the factors of these sequences.

[0097] [Function 3]

[0098] b1 = b2 - h

[0099] For example, the forming elements 10 of the exchanger according to the invention can be produced by additive manufacturing using selective melting on a powder bed. As described above, when these forming elements 10 are integrated with the plate 6, the forming elements can be manufactured together with the plate 6, or when the forming elements are integrated with the manifold C or distributor D, the forming elements can be manufactured together with the manifold or distributor.

[0100] Figure 5b shows alternative embodiments of ellipses E1 and E2. Ellipses E1 and E2 have the same center O, and ellipse E2 is larger than ellipse E1. b2 is greater than b1 but greater than a1. a2 is greater than a1.

[0101] Furthermore, the boxed portion of Figure 5b shows that the region of interest selected for the curvature of the formed element is not necessarily a quarter of the large ellipse, but can represent a quarter of the smaller ellipse.

Claims

1. A plate-type heat exchanger (1) between a first fluid and a second fluid, the first fluid being intended to flow along a first direction (X) and the second fluid being intended to flow along a second direction (Y), the second direction being different from the first direction, the heat exchanger comprising stacked stages (2, 3) for the flow of the first fluid, each stage comprising: - Two parallel plates (6) are positioned a distance apart from each other to define a flow channel (7) between the two parallel plates for the flow of the first fluid. - A series of fins (9) arranged between the plates (6) to define a series of conduits for the flow of the first fluid in the flow channel (7). - First forming elements, the first forming elements being used to allow the first fluid to enter the flow channel (7), these first forming elements being located at the entrance of the flow channel at each of the plates to define a first convergence path for guiding the first fluid into the flow channel, and / or - Second forming elements, the second forming elements being used for the outlet of the first fluid flowing out of the flow channel, these second forming elements being located at the outlet of the flow channel at each of the plates (6) to define a second expanding path for guiding the first fluid outside the flow channel, Characterized by the fact that each of the first forming element and the second forming element has a serrated portion in cross-section, the serrated portion comprising: - A first outer peripheral edge (B1) comprising a generally straight first end (B11), a second end (B12) and a convex curved portion (B13), the generally straight first end being for connection to a plate in the plate (6) defining a first flow channel in the flow channel (7), the second end being located at the tip (14) of the forming element (10), and the convex curved portion extending between the first end (B11) and the second end (B12); - A second outer peripheral edge (B2), comprising a generally straight third end (B21), a fourth end (B22), and a concave curved portion (B23), the generally straight third end being for connection to a plate in the plate (6) defining a second flow channel adjacent to the first flow channel in the flow channel (7), the fourth end being located at the tip of the forming element and oriented at an angle of less than 90° relative to the second end (B12), the concave curved portion extending between the third end (B21) and the fourth end (B22). The concave curved portion (B23) and convex curved portion (B13) of the first forming element and the second forming element have different curvatures to define the first convergence path and the second diverging path. Furthermore, the curvature of the convex curved portion (B13) corresponds to one-quarter of the curvature of the first ellipse (E1), which has a larger radius a1 at the second end and a smaller radius b1 at the first end. The curvature of the concave curved portion (B23) corresponds to a portion of the curvature of the second ellipse (E2), which has a larger radius a2 at the fourth end and a smaller radius b2 at the third end. The first ellipse (E1) and the second ellipse (E2) have the same center, and a2 and b2 are greater than a1 and b1, respectively.

2. The heat exchanger (1) according to claim 1, wherein, The second end (B12) located at the tip (14) of the forming element (10) forms an angle with the first end (B11), the angle being between 60° and 95°.

3. The heat exchanger (1) according to claim 2, wherein, The tips (14) of the first forming element and the second forming element are tapered.

4. The heat exchanger (1) according to any one of claims 1 to 3, wherein, The first forming element is carried by a manifold (C) which is fitted to the inlet of the plate (6), and the second forming element is carried by a distributor (D) which is fitted to the outlet of the plate.

5. The heat exchanger (1) according to any one of claims 1 to 3, wherein, The first forming element and the second forming element are integrated with the plate (6).

6. The heat exchanger (1) according to any one of claims 1 to 3, wherein, All the first forming elements are identical, and all the second forming elements are identical.

7. The heat exchanger (1) according to any one of claims 1 to 3, wherein, [Function 1] in, h It is the distance between the plates (6). Rd It is a parameter that controls the change of the cross section of the corresponding path (12).

8. The heat exchanger (1) according to claim 7, wherein, [Function 2] [Function 3] in, spacing It is the distance between two adjacent flow channels (7).

9. The heat exchanger (1) according to any one of claims 1 to 3, wherein, The forming elements are different and their dimensions are determined according to an arithmetic or geometric sequence, where a 1，n It is a1, a of the nth forming element. 1，n+1 It is a1 of the (n+1)th forming element. [Function 4] Or [Function 5] Among them, R a R is the common difference of the arithmetic sequence. g It is the common ratio of the geometric sequence.

10. The heat exchanger (1) according to any one of claims 1 to 3, wherein, The second end (B12) located at the tip (14) of the forming element (10) is oriented approximately perpendicular to the first end (B11).

11. The heat exchanger (1) according to any one of claims 1 to 3, wherein, The fins (9) are arranged approximately vertically between the plates (6).

12. The heat exchanger (1) according to claim 1, wherein, The heat exchanger is used in aircraft turbines.

13. The heat exchanger (1) according to claim 2, wherein, The angle is between 70° and 90°.

14. A turbine comprising at least one heat exchanger (1) according to any one of claims 1 to 13.

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