Advanced disturbance elements for improving pipe performance
The heat exchanger tube design optimizes fluid mixing and reduces pressure loss through specific geometric configurations, enhancing thermal performance by 16-45% across varying flow rates.
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Patents
- Current Assignee / Owner
- VALEO ELECTRIFICATION
- Filing Date
- 2022-11-23
- Publication Date
- 2026-07-01
AI Technical Summary
Existing heat exchangers face a trade-off between optimizing heat exchange and minimizing pressure loss, as increasing disturbance elements for fluid mixing leads to significant pressure drops, limiting efficiency.
A heat exchanger tube design featuring longitudinally aligned disturbance elements with specific geometric configurations and material integration, optimized to enhance fluid mixing while minimizing pressure loss.
The design achieves improved heat exchange efficiency with reduced pressure loss, demonstrated by a 16-45% improvement in thermal performance across varying Reynolds numbers.
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Abstract
Description
[0001] The field of the present invention is that of heat exchangers, in particular intended to equip the air conditioning loops of motor vehicles or to cool the engine of a vehicle.
[0002] Heat exchangers, particularly those used in vehicle air conditioning systems, are designed to allow adjacent circulation of two different fluids in two separate spaces, thus enabling heat exchange between the fluids without mixing them. One type of heat exchanger used in the automotive industry is the tube-and-tube heat exchanger. This type of exchanger consists of a stack of tubes brazed together and arranged to define the spaces through which the fluids circulate. Within heat exchangers and the thermodynamic circuits to which they are connected, the fluids circulate, dissipating or absorbing thermal energy.
[0003] The efficiency of heat exchangers and thermodynamic circuits is primarily determined by the heat exchange between the fluids flowing through them. Therefore, the design of heat exchangers is sought in which the heat exchange between the fluids circulating within them is optimized. To this end, one can, in particular, aim to mix each fluid within the space in which it circulates, in order to increase heat exchange between the fluids, and it is known to equip heat exchangers with elements that disrupt the fluid flow.
[0004] It is understood that to increase fluid mixing, it is possible to increase the number of disturbance elements and thus try to place them closer together. However, while this solution improves mixing and the amount of heat exchange, it does not satisfactorily address the aforementioned problem of optimizing heat exchange because multiplying the disturbance elements causes a significant pressure drop that limits fluid circulation and therefore the efficiency of the heat exchanger.
[0005] The aim of the present invention is therefore to resolve the disadvantages described above by designing a tube for a heat exchanger arranged to improve the heat exchange between the fluids flowing through the heat exchanger, in particular by limiting the pressure losses suffered by these fluids.
[0006] More specifically, the invention relates to a heat exchanger tube according to claim 1.
[0007] According to one aspect of the invention, the length of the tube is defined along the longitudinal direction, the first wall extending along the longitudinal direction.
[0008] According to one aspect of the invention, the first and second disturbance elements are distant from each other.
[0009] According to one aspect of the invention, the first flat wall comprises a first internal face turned towards the fluid circulation channel.
[0010] According to one aspect of the invention, each of the first and second perturbation elements emerges from the first inner face from its base and culminates at its crest.
[0011] According to one aspect of the invention, the base of a perturbation element and the crest of said element are in a homothetic relationship.
[0012] According to one aspect of the invention, the first and second disturbance elements extend into the fluid circulation channel, so as to disturb the flow of this fluid.
[0013] According to one aspect of the invention, each of the first and second ridges is contained in a plane parallel to the first flat wall, in other words, the altitude of each of the first and second ridges relative to the first flat wall is substantially constant all along this ridge.
[0014] According to one aspect of the invention, the tube comprises a second flat wall extending along the longitudinal direction, this second flat wall being parallel to the first flat wall.
[0015] According to one aspect of the invention, the second flat wall comprises a second internal face facing the fluid circulation channel.
[0016] The height h of a disturbance element is defined as the distance between the inner face of the wall bearing the disturbance element and the crest of said disturbance element, this distance being measured along a direction perpendicular to the first flat wall.
[0017] The height H of the channel is defined as the distance between the first inner face and the second inner face, this distance being measured along a direction perpendicular to the first flat wall.
[0018] According to one aspect of the invention, the perturbation elements forming the pair of perturbation elements are of the same height h.
[0019] According to one aspect of the invention, the ratio of the height h of the disturbance elements to the height H of the channel is between 0.1 and 0.4, in particular between 0.2 and 0.3.
[0020] According to one aspect of the invention, the first and second flat walls respectively comprise a first and a second external faces turned towards the outside of the tube.
[0021] The thickness e of a plane wall is defined as the distance between the inner face of said plane wall and the first outer face of said plane wall, measured along a direction perpendicular to the first plane wall.
[0022] According to one aspect of the invention, the ratio of the height h of the disturbance elements to the thickness e of the first flat wall is between 0.1 and 4.0, in particular between 0.5 and 2.5.
[0023] According to one aspect of the invention, the first and second crests of the disturbance elements are spaced at a distance of between 1 and 3 mm.
[0024] According to one aspect of the invention, the pairs of perturbation elements are arranged alternately on the first flat wall and on the second flat wall.
[0025] According to one aspect of the invention, two pairs of successive perturbation elements of the same flat wall aligned along the longitudinal direction are spaced at a pitch of between 2 and 6 mm.
[0026] The step between two pairs of successive perturbation elements aligned along the longitudinal direction is defined as the distance between the geometric centers of the pairs of perturbation elements.
[0027] According to one aspect of the invention, the first straight line intersects the second ridge between 1 / 3 and 2 / 3 of its length.
[0028] According to one aspect of the invention, the first internal face has a width L, defined along the first internal face and perpendicular to the longitudinal direction.
[0029] According to one aspect of the invention, the height h of the disturbance elements is between 0.1 and 0.6 mm, in particular between 0.2 and 0.5 mm.
[0030] According to one aspect of the invention, the tube comprises a plurality of pairs of perturbation elements aligned in the longitudinal direction of the tube.
[0031] According to one aspect of the invention, the pairs of perturbation elements of the same flat wall are aligned alternately on a first and a second row, each row occupying predominantly one half of the flat wall, the half being defined by a plane following both the longitudinal direction and a direction perpendicular to the flat wall, this plane passing through the middle of the width L of the inner face.
[0032] According to one aspect of the invention, the tube includes additional disturbance elements, in addition to pairs of disturbance elements, the crest of which has a different shape from the crest of the pairs of disturbance elements, whether it be in the form of chevrons, circles, rectangles or ovals.
[0033] According to one aspect of the invention, the additional perturbation elements are intercalated between two pairs of perturbation elements.
[0034] According to one aspect of the invention, the minimum spacing between the first and second crests of a pair of disturbance elements is strictly less than the minimum spacing between any one of the first and second crests and any other crest of a disturbance element or additional disturbance element of the same plane wall.
[0035] According to one aspect of the invention, the number of additional perturbation elements aligned along a line perpendicular to the longitudinal direction and extending along the width L of the inner face is greater than one.
[0036] According to one aspect of the invention, a pair of successive perturbation elements and an additional perturbation element of the same flat wall aligned along the longitudinal direction are spaced at a pitch of between 1 and 7 mm.
[0037] According to one aspect of the invention, the pitch between either two pairs of perturbation elements, or a pair of perturbation elements and an additional perturbation element, aligned along the longitudinal direction, increases progressively along the longitudinal direction D of the tube.
[0038] According to one aspect of the invention, either the disturbance elements, or the disturbance elements and the additional disturbance elements, are made from the same material as the tube; in other words, the tube and the disturbance elements, or the tube and the additional disturbance elements, are made from the same block of material, one not being able to be separated from the other without causing the destruction of the tube.
[0039] According to one aspect of the invention, either the disturbance elements, or the disturbance elements and additional disturbance elements, are manufactured by stamping, pressing or metal additive manufacturing.
[0040] According to one aspect of the invention, the tube comprises an intermediate wall dividing the internal conduit defined inside the tube into two channels.
[0041] According to one aspect of the invention, either the disturbance elements, or the disturbance elements and additional disturbance elements, are arranged on one and the other of the channels.
[0042] The invention also relates to a heat exchanger comprising a plurality of tubes, connected to each other through two manifolds, characterized in that at least one of said tubes is according to the invention, said plurality of tubes defining a circulation circuit for a fluid capable of being disturbed by the disturbance elements and a circulation space for air.
[0043] The features, variations, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variations of the invention may be conceived comprising only a selection of features described herein, isolated from the other described features, if this selection of features is sufficient to confer a technical advantage.
[0044] Other features and advantages of the invention will become apparent from the following description on the one hand, and from several illustrative and non-limiting examples of embodiments given with reference to the attached schematic drawings on the other hand, in which: There Figure 1 is a schematic, front-view representation of a heat exchanger consisting of a plurality of tubes according to the invention. Figure 2 is a cross-sectional view of a tube according to the invention, shown in perspective. Figure 3 is a cross-sectional view of the inside of the tube along a plane parallel to the tube wall. Figure 4 is a top view, in cross-section, of the interior of the tube, along a plane parallel to the tube wall, of a disturbance element according to the invention. Figure 5 is a cross-sectional view along the longitudinal direction of a tube according to the invention. Figure 6 is a cross-sectional view of the inside of the tube along a plane extending along the longitudinal direction and perpendicular to the tube wall, according to an embodiment of the invention comprising several geometries of perturbation elements. Figure 7 is a graph showing the evolution of the improvement factor as a function of the Reynolds number measured for a reference tube and for a tube according to the present invention.
[0045] There Figure 1 The figure shows a heat exchanger 1 according to the invention, configured for installation on the front of a vehicle, particularly a motor vehicle, and for enabling, in particular, the exchange of heat between two fluids, including, for example, a fluid and an airflow. The heat exchanger comprises a plurality of tubes 2 according to the invention, through which the fluid circulates. The tubes 2 are arranged parallel to each other in a stacking direction E, here vertical, and define a plurality of conduits through which the fluid can flow.
[0046] The space between two successive tubes 2 according to the invention defines a space 110 through which an airflow can circulate in order to exchange heat with the fluid circulating in the tubes 2. In order to increase the heat exchange between the fluid and the airflow, fin-shaped heat sinks 120 are arranged in the space through which the airflow circulates. The purpose of these heat sinks 120 is to increase the contact surface with the airflow to optimize the heat exchange between the fluid and the airflow. To facilitate reading the Figure 1 and the vertical stacking of the tubes, the 120 heat sinks have only been partially represented, it being understood that they can extend over the entire longitudinal dimension of the tubes between which these heat sinks are arranged.
[0047] Each tube 2 according to the invention is connected to a first manifold 130 and a second manifold 140, through which the fluid circulates and supplies the tubes. The first manifold 130 is arranged to distribute the fluid entering the heat exchanger 1 into the various tubes 2 constituting said exchanger. The second manifold 140 is arranged to collect the fluid that has passed through the tubes 2 and discharge it from the heat exchanger 1. The first and second manifolds 130 and 140 are positioned opposite each other with respect to the stack of tubes 2, each tube extending longitudinally so as to be connected at one end to the first manifold 130 and at the other end to the second manifold 140.
[0048] The heat exchanger 1 also includes means for connecting these manifolds to a fluid circuit external to the heat exchanger 1 and not shown here. The first manifold 130 is thus connected to a first connection fitting 150 through which the fluid can enter the heat exchanger 1, the second manifold 140 being connected to a second connection fitting 160 through which the fluid can exit the heat exchanger 1.
[0049] There Figure 2 presents the arrangement of the disturbance elements according to the invention. The tube 2 for heat exchanger 1 defines a fluid circulation channel 100, this channel having a longitudinal direction D. The length of this tube is defined along the longitudinal direction D.
[0050] This tube 2 has a first flat wall 3 extending along the longitudinal direction D. It includes a pair of disturbance elements 11, 12 consisting of a first disturbance element 11 and a second disturbance element 12 present on this first flat wall 3, in the fluid circulation channel 100, so as to disturb the flow of this fluid.
[0051] Each of the first and second disturbance elements 11, 12 includes in particular a local deformation of this first flat wall 3 of the tube 2 towards the interior of the tube 2.
[0052] There Figure 3 shows a cross-sectional view of the tube along a plane parallel to the first flat wall 3 of the tube 2. The first and second perturbation elements 11, 12 extend respectively between a first base 21 and a first ridge 31 and a second base 22 and a second ridge 32, said first ridge 31 having an elongated shape along a first straight line 41 and said second ridge 32 having an elongated shape along a second straight line 42. The first straight line 41 intersects the second ridge 32. A third straight line 43 parallel to the longitudinal direction D passing through the center of the first base 21 intersects the second base 22.
[0053] The intersection between the first line 41 and the longitudinal direction D forms an angle A, which is between 20° and 60°, in particular between 30° and 50°, ideally 40°. The intersection between the second line 42 and the longitudinal direction D forms an angle B, which is between 45° and 85°, in particular between 55° and 75°, ideally 65°.
[0054] The first straight line 41 intersects the second ridge 32 between 1 / 3 and 2 / 3 of its length.
[0055] The first and second perturbation elements 11, 12 are separated from each other. The first and second crests 31, 32 of the perturbation elements 11, 12 are spaced between 1 and 3 mm apart.
[0056] The first ridge 31 and the second ridge 32 are of the same length l, the length l being measured between the two free ends of the ridge considered.
[0057] The first internal face 5 has a width L, defined along the first internal face 5 and perpendicular to the longitudinal direction D.
[0058] There Figure 4 shows a top cross-sectional view, from inside tube 2, of a pair of perturbation elements 11, 12. Each of the first and second perturbation elements 11, 12 emerges from the first inner face from its base 21, 22 and culminates at its crest 31, 32. The base 21, 22 of a perturbation element 11, 12 and the crest 31, 32 of said element are in a homothetic relationship.
[0059] Each of the first and second ridges 31, 32 is contained in a plane parallel to the first flat wall 3, in other words, the altitude of each of the first and second ridges 31, 32 with respect to the first flat wall 3 is substantially constant all along this ridge 31, 32.
[0060] There Figure 5 This figure presents a cross-sectional view along the longitudinal direction D of a tube 2 according to the invention. The first flat wall 3 comprises a first internal face 5 facing the fluid circulation channel 100. The tube 2 has a second flat wall 4 extending along the longitudinal direction D, this second flat wall 4 being parallel to the first flat wall 3. The second flat wall 4 comprises a second internal face 6 facing the fluid circulation channel 100.
[0061] The height h of the perturbation element 11 is defined as the distance between the first internal face 5 and the ridge 31, this distance being measured along a direction perpendicular to the first flat wall 3.
[0062] The height H of channel 100 is defined as the distance between the first inner face 5 and the second inner face 6, this distance being measured along a direction perpendicular to the first flat wall 3.
[0063] The disturbance elements 11, 12 forming the pair of disturbance elements are of the same height h. The ratio of the height h of the disturbance elements 11, 12 to the height H of the channel is between 0.1 and 0.4, in particular between 0.2 and 0.3.
[0064] The first and second flat walls 3, 4 have respectively a first and a second external faces 7, 8 turned towards the outside of the tube 2.
[0065] The thickness e of the first plane wall 3 is defined as the distance between the first inner face 5 and the first outer face 7, measured along a direction perpendicular to the first plane wall 3.
[0066] The ratio of the height h of the disturbance elements 11, 12 to the thickness e of the first flat wall 3 is between 0.1 and 4.0, in particular between 0.5 and 2.5.
[0067] The height h of the disturbance elements 11, 12 is between 0.1 and 0.6 mm, in particular between 0.2 and 0.5 mm.
[0068] Tube 2 has an intermediate wall 50 dividing the internal conduit defined inside tube 2 into two channels 100, 101.
[0069] Tube 2 includes additional disturbance elements 13, in addition to the pairs of disturbance elements 11. The disturbance elements 11, 12 and the additional disturbance elements are arranged in both channels 100, 101.
[0070] There Figure 6 is a cross-sectional view of the interior of tube 2 along a plane extending along the longitudinal direction D and perpendicular to the first flat wall 3 of tube 2, according to an embodiment of the invention comprising several perturbation element geometries. The pairs of perturbation elements 11, 12 are also arranged alternately on the first flat wall 3 and on the second flat wall 4.
[0071] Tube 2 comprises a plurality of pairs of perturbation elements 11, 12 aligned in the longitudinal direction D of tube 2. Two successive pairs of perturbation elements 11, 12 on the same plane wall, aligned along the longitudinal direction D, are spaced at a pitch P between 2 and 6 mm. The pitch P between two successive pairs of perturbation elements 11, 12 aligned along the longitudinal direction is defined as the distance between the geometric centers of the pairs of perturbation elements 11, 12.
[0072] The pairs of perturbation elements 11, 12 of the first plane wall 3 are aligned alternately on a first and a second row, each row occupying mostly one half of the first plane wall 3, the half being defined by a plane F following both the longitudinal direction and a direction perpendicular to the first plane wall 3, this plane passing through the middle of the width L of the first internal face 5.
[0073] Tube 2 also includes additional perturbation elements 13, in addition to the pairs of perturbation elements 11, 12, whose crest has a different shape from the crest of the pairs of perturbation elements 11, 12, whether it be a chevron, circle, rectangle, or oval shape. The additional perturbation elements 13 are intercalated between two pairs of perturbation elements 11, 12.
[0074] The minimum spacing between the first crest 31 and the second crest 32 of a pair of perturbation elements 11, 12 is strictly less than the minimum spacing between any of the first and second crests 31, 32 and any other crest of perturbation element 11, 12 or additional perturbation element 13 of the first plane wall 3.
[0075] The number of additional perturbation elements 13 aligned along a line perpendicular to the longitudinal direction D and extending along the width L of the first inner face is greater than one.
[0076] A pair of successive perturbation elements 11, 12 and an additional perturbation element 13 of the first flat wall 3, aligned along the longitudinal direction D, are spaced at a pitch p of between 1 and 7 mm. According to another aspect of the invention, either the pitch P between two pairs of perturbation elements 11, 12, or the pitch p between a pair of perturbation elements 11, 12 and an additional perturbation element 13, aligned along the longitudinal direction D, increases progressively along the longitudinal direction D of the tube 2.
[0077] The disturbance elements 11, 12 and the additional disturbance elements 13 are made from the same material as the tube 2. In other words, the tube 2 and the disturbance elements 11, 12 as well as the tube 2 and the additional disturbance elements 13 are made from the same block of material, one cannot be separated from the other without causing the destruction of the tube 2. The disturbance elements 11, 12 and the additional disturbance elements 13 are manufactured by deep drawing, stamping or metal additive manufacturing.
[0078] There Figure 7 This graph shows the evolution of the improvement factor, EHF, as a function of the Reynolds number, Re, measured for a reference tube D1 and for a tube according to the present invention, D2. These data are derived from experimental measurements. The improvement factor is defined as the ratio of the Nusselt number of the tube under consideration to the Nusselt number of the reference tube D1 at an equivalent Reynolds number, divided by the ratio, raised to the power of 1 / 3, of the friction factor of the tube under consideration to the friction factor of the reference tube D1 at an equivalent Reynolds number. This coefficient aims to compare the improvement in thermal performance while taking into account the impact on the resulting pressure losses.
[0079] The reference tube used here is a tube developed specifically for high Reynolds numbers. The graph of the Figure 7shows that the tube according to the invention has a superior improvement factor to the reference tube over the entire tested range, i.e. for Reynolds numbers ranging from 100 to 1000. This improvement varies between 16% and 45% depending on the flow rates.
Claims
1. Tube (2) for a heat exchanger (1) defining a fluid circulation channel (100), said channel (100) extending in a longitudinal direction (D) and comprising a first planar wall (3) comprising at least one pair of turbulence elements (11, 12), said pair of turbulence elements (11, 12) being formed by a first turbulence element (11) and a second turbulence element (12), the first and second turbulence elements (11, 12) being constituted by a local deformation of said first planar wall (3) towards the interior of the tube (2), characterized in that said first and second turbulence elements (11, 12) extend respectively between a first base (21) and a first crest (31) and between a second base (22) and a second crest (32), said first crest (31) having an elongated shape along a first straight line (41) and said second crest (32) having an elongated shape along a second straight line (42), said first straight line (41) intersecting said second crest (32), and in that a third straight line (43) parallel to the longitudinal direction (D) and passing through the center of the first base (21) intersects the second base (22), characterized in that the first crest (31) and the second crest (32) have the same length (I), the length (l) being measured between the two free ends of the crest (31, 32) considered, the intersection between the first straight line (41) and the longitudinal direction (D) forming an angle A, which is between 30° and 50°, and the intersection between the second straight line (42) and the longitudinal direction (D) forming an angle B, which is between 45° and 85°, in particular between 55° and 75°.
2. Tube (2) according to claim 1, characterized in that the ratio of the height h of the turbulence elements (11, 12) to the height H of the channel (100) is between 0.1 and 0.4, in particular between 0.2 and 0.3.
3. Tube (2) according to claim 1 or 2, characterized in that the ratio of the height h of the turbulence elements (11, 12) to the thickness e of the first planar wall (3) is between 0.1 and 4.0, in particular between 0.5 and 2.5.
4. Tube (2) according to one of the preceding claims, characterized in that the first and second crests (31, 32) of the turbulence elements (11, 12) are spaced apart by a distance between 1 and 3 mm.
5. Tube (2) according to one of the preceding claims, characterized in that it comprises a second planar wall (4) parallel to the first planar wall (3), the pairs of turbulence elements (11, 12) being arranged alternately on the first planar wall (3) and on the second planar wall (4).
6. Tube (2) according to one of the preceding claims, characterized in that two successive pairs of turbulence elements (11, 12) of the same planar wall (3, 4) aligned along the longitudinal direction (D) are spaced apart by a pitch (P) between 2 and 6 mm.
7. Tube (2) according to one of the preceding claims, comprising additional turbulence elements (13), in addition to the pairs of turbulence elements (11, 12), and whose crest has a different shape from the crest (31, 32) of the turbulence elements (11, 12).
8. Heat exchanger (1) comprising a plurality of tubes (2), connected to each other through two collectors (130, 140) characterized in that at least one of said tubes is according to any one of the preceding claims, said plurality of tubes (2) defining a circulation circuit for a fluid capable of being disturbed by the turbulence elements (11, 12) and a space (110) for air circulation.