Heat exchanger having optimized fluid passages

Abstract

The invention relates to a heat exchanger that is configured to permit an exchange of heat between a first fluid and a second fluid that circulate in passage paths formed by plates (14a, 14b) and fins (16a, 16b) of the heat exchanger, the fluids flowing in a multitude of passage channels (10) each consisting of a closed space (12) delimited by two adjacent plates and two adjacent fins, characterized in that each plate extends along a non-planar surface following at least one oscillating curve, and each fin further following at least one second oscillating curve along at least one second main direction, in such a way that each passage path allows the fluid to flow in the closed space along a fluid direction defined by a generatrix that is a combination at least of the first oscillating curve and the second oscillating curve.

Description

Technical field of the invention

[0001] The invention relates to a heat exchanger. In particular, the invention relates to a plate and fin heat exchanger suitable for use in an air conditioning system, for example in an air, rail or land vehicle. Technological background

[0002] Heat exchangers are used to enable heat exchange between two or more fluids, particularly to cool or heat one of the fluids using another fluid. Heat exchangers are used in many contexts, including air conditioning systems for aircraft, rail, or land vehicles, where they are used to regulate the temperature of the air conditioned by the air conditioning system at different stages of conditioning.

[0003] Among the various types of heat exchangers, plate-fin heat exchangers are a type of design that uses plates and finned chambers to transfer heat between fluids. The circulation channels formed by the plates and fins allow each fluid to circulate without mixing with other fluids, while maximizing the heat transfer surface-to-volume ratio. These types of exchangers are particularly popular in the transportation industry, especially the aviation industry, for their compact size and light weight, while offering good performance.

[0004] For several decades, plate heat exchangers have been manufactured from a succession of flat plates, between which fins formed by a corrugated plate are arranged to form circulation channels for each fluid. The plates and fins are manufactured independently and then brazed together to form the heat exchangers. Flat plates and corrugated plates are made of metal, for example aluminum or aluminum alloy, or stainless steel.

[0005] The geometries of the fins formed by the corrugated plate can be of various shapes, for example rectangular, triangular, wave-shaped, etc. Different configurations are used depending on the needs in terms of exchange surface, pressure loss, etc.

[0006] The inventors sought to maximize the heat exchange between the fluids by minimizing the pressure drop due to the passage of each fluid in the exchanger, in particular for the fluid which heats up during the passage in the exchanger.

[0007] EP 3 193 125 A1 discloses a heat exchanger comprising two fluid circulation circuits isolated from each other and a plurality of circulation channels all conforming to a curvilinear profile which can take different forms, for example a sinusoidal, helical, or coil pattern. Objectives of the invention

[0008] The invention aims to provide an optimized heat exchanger.

[0009] The invention aims in particular to provide, in at least one embodiment, a heat exchanger maximizing heat exchange.

[0010] The invention also aims to provide, in at least one embodiment of the invention, a heat exchanger minimizing pressure losses.

[0011] The invention also aims to provide, in at least one embodiment of the invention, a less bulky and lighter heat exchanger.

[0012] The invention also aims to provide, in at least one embodiment of the invention, a compact heat exchanger which can be used in an air, rail or land vehicle, in particular in an air conditioning system. Statement of the invention

[0013] To this end, the invention relates to a heat exchanger, configured to allow heat exchange between a first fluid and a second fluid circulating respectively in at least a first passage path and a second passage path, said passage paths being formed by plates and fins of the heat exchanger and being configured to lead each fluid from a fluid inlet to a fluid outlet, the fluids circulating in a multitude of passage channels each formed by a closed space delimited by two adjacent plates and two adjacent fins, characterized in that each plate extends along a non-planar surface defined between the fluid inlet and the fluid outlet of the associated passage path, said non-planar surface following at least a first oscillating curve in at least a first main direction around a mean surface of the plate,and in that each fin comprises an upper edge configured to be in contact with one of the adjacent plates, called the upper plate, and a lower edge configured to be in contact with the other adjacent plate, called the lower plate, each fin further following at least one second oscillating curve in at least one second main direction around a mean surface of the fin, so that each passage path allows the circulation of the fluid in the closed space in a fluid direction between the fluid inlet and the fluid outlet, called the circulation axis, defined at any point of the curve by a generating curve which is a combination at each point at least of the first oscillating curve and the second oscillating curve.,

[0014] A heat exchanger according to the invention therefore makes it possible, thanks to the particular geometry of the passage channels carried by a generating curve which is a combination of at least two oscillating curves, to maximize the exchange surface between the fluids while maintaining good performance in terms of pressure losses, compared to a conventional plate-fin exchanger. The combination of the oscillating curves makes it possible to obtain generating curves of different shapes, making it possible to form any type of geometry.

[0015] The plates and fins each follow an oscillating curve allowing the exchange surfaces to be increased without any significant impact on pressure losses.

[0016] In particular, the heat exchange efficiency is improved by around 35% for a reduction of at least 40% in mass and 20% in effective volume.

[0017] The formation of channels in the heat exchanger allows in particular a much lower pressure loss than multi-path heat exchangers, where the fluid can follow several paths via bifurcations, said bifurcations being formed by a channel comprising the other fluid of the exchanger.

[0018] An oscillating curve is a curve lying alternately on one side and the other of a curve that is the average of this oscillating curve. According to certain variants of the invention, the oscillating curves may be periodic: the curves may, for example, be sinusoidal, triangular, etc.

[0019] Advantageously and according to the invention, the first curve and the second curve have the following characteristics: 0,1 < γ < 1 0,2 < ε < 5 with γ being equal to the average amplitude of the curve divided by the average period of the curve, and ε being equal to the average step of the curve divided by the amplitude of the curve.

[0020] In the example of the figure 2 representing two sinusoidal curves forming the generating curve of a passage channel as represented with reference to the figure 1, the curve 20b extends in the X direction, has peaks or summits, each forming a ridge line, and has troughs, each forming a trough line. The peak portions and the trough portions are arranged alternately in the Y direction, which is characteristic of a curve oscillating about the X axis. Each point on the curve can be expressed in terms of a coordinate that can be expressed in terms of the X and Y axes. Only one coordinate value along the X axis is associated with each single point on the curve, but several points on the curve have the same coordinate value along the Y axis due to the oscillation of the curve.

[0021] Similarly, curve 20a oscillates around the X axis with oscillations along the Z axis.

[0022] When the average curve around which curves 20a or 20b oscillate is not straight, the reference point is expressed at each point of the curve by a principal direction X which corresponds to the tangent to the average curve at this point of the curve.

[0023] The difference in height between a peak and a trough represents the amplitude. The average amplitude is also referred to as the average difference in height between a peak and a trough.

[0024] The distance between two adjacent vertices relative to the Y axis represents the period, the average period being the average distance between two successive vertices.

[0025] The distance between two adjacent passage channels is defined by the pitch. The average pitch is also understood to mean the average distance between two channels.

[0026] According to this aspect of the invention, these characteristics make it possible to ensure a low pressure drop while allowing an increase in the heat exchange surface. An average amplitude that is too large compared to the period or the step would result in significant pressure drops, despite the significant increase in the heat exchange surface. These characteristics allow a good compromise between the increase in the exchange surface and the pressure drops.

[0027] Advantageously and according to the invention, the first curve and / or the second curve is continuous.

[0028] Advantageously and according to the invention, the first curve and / or the second curve is discontinuous.

[0029] According to these aspects of the invention, each curve can be either discontinuous or continuous. Discontinuous curves allow for a further increase in the heat exchange surface area, while continuous curves have less impact on pressure losses.

[0030] Advantageously and according to the invention, the first curve and / or the second curve oscillate with variable amplitude and / or frequency.

[0031] According to this aspect of the invention, the amplitude or frequency of oscillation of the curves are variable, which makes it possible to adjust the pressure drop or the heat exchange of the fluid, for example upstream or downstream of the channels.

[0032] Advantageously and according to the invention, the fluids are gaseous or liquid.

[0033] According to this aspect of the invention, the heat exchanger can be used in different contexts. In particular, the heat exchanger can be used in the field of transport (aeronautics, rail, land, etc.) where heat exchanges take place between gas and gas, between gas and liquid or between liquid and liquid. Each of these different types of fluids can be a hot source or a cold source.

[0034] According to the invention, the circulation axes of the channels of the first passage are substantially orthogonal to the circulation axes of the channels of the second passage.

[0035] According to this aspect of the invention, the exchangers thus formed are cross-pass.

[0036] Advantageously and according to the invention, the exchanger is manufactured by additive manufacturing.

[0037] According to this aspect of the invention, additive manufacturing makes it possible to easily obtain the complex geometries formed by the channels. Advantageously, the material used can be metal, in particular a Nickel alloy (Ni625, Ni718), an Aluminum alloy (AS7G06, AS10), Titanium (TA6V) or stainless steel (15-5Ph, 316L, 17-4Ph) or plastic materials such as polymers of the PAEK type (PEEK, PEKK, etc.) or the Silicon Carbide family.

[0038] Plates and fins can be produced together by additive manufacturing and form a whole. Thus, the distinction between plates and fins stated above and below describes a differentiation of functions, particularly in the definition of the passageways and channels, but the entire exchanger can be manufactured in one go by additive manufacturing without having to manufacture the plates and fins separately.

[0039] The invention also relates to a system comprising a heat exchanger according to the invention, and an aircraft comprising a heat exchanger according to the invention.

[0040] The invention also relates to a heat exchanger, an air conditioning system and an aircraft, characterized in combination by all or part of the features mentioned above or below. List of figures

[0041] Other aims, characteristics and advantages of the invention will appear on reading the following description given solely for non-limiting purposes and which refers to the appended figures in which: [ Fig. 1 ] is a schematic perspective view representing a single passage channel of a passage path of a heat exchanger according to a first embodiment of the invention. Fig. 2] is a schematic view of the curves carrying the passage channel of the passage path of a heat exchanger according to the first embodiment of the invention. [ Fig. 3 ] is a schematic perspective view showing a passage path of a heat exchanger according to one embodiment of the invention. Fig. 4 ] is a schematic perspective view showing a heat exchanger according to one embodiment of the invention. Detailed description of an embodiment of the invention

[0042] In the figures, scales and proportions are not strictly respected, for the purposes of illustration and clarity.

[0043] Furthermore, identical, similar or analogous elements are designated by the same references in all figures.

[0044] There figure 1 schematically illustrates in perspective a single passage channel 10 of a passage path of a heat exchanger according to an embodiment of the invention.

[0045] The channel 10 is formed of an empty space 12 delimited by two plates 14a and 14b and two adjacent fins 16a and 16b of the heat exchanger. The channel extends in a main direction called the circulation axis 18, representing the direction in which a fluid passing through the exchanger moves in the channel. A section perpendicular to the direction axis forms a flat passage section closed by the walls formed by the two plates 14a and 14b and the two adjacent fins 16a and 16b. The plate 14a forms a plate called the upper plate and the plate 14b forms a plate called the lower plate. The fins are in contact with these two plates.

[0046] There figure 2 schematically illustrates two oscillating curves 20a and 20b followed respectively by the plates 14a and 14b, and by the fins 16a and 16b, making it possible to obtain the undulating shape of the passage channel.

[0047] The curves here are continuous and sinusoidal, but the curves can take different shapes, for example triangular, etc. The curves are oscillating. In this embodiment, the two curves oscillate and are periodic (i.e. of constant frequency and constant maximum and minimum amplitude between each period). The first oscillating curve 20a represents the oscillation applied to the plates 14a and 14b and the second curve 20b represents the oscillation applied to the fins 16a and 16b. The combination at any point of the two curves 20a and 20b corresponds to a generating curve representing the circulation of the fluid in the passage channel 10.

[0048] The curves here oscillate around the circulation axis, but can oscillate in different directions, as shown in the figure 3 .

[0049] There figure 3represents a passage path 30 of a heat exchanger according to an embodiment of the invention.

[0050] A passage path 30 comprises several passage channels 110 and allows the circulation of a fluid, the fluid passing through the different passage channels 110 of the passage path 30. The passage path is formed by two plates (only one plate 114 being visible in the figure) and a plurality of fins 116, so as to compose the different channels 110 all oriented along axes 118 of parallel directions.

[0051] In this embodiment, one of the curves 20c followed by the plates forming the passage channels 110 is included in a plane orthogonal to the mean plane 32 of the plate 114 and thus forms the oscillating curve followed by the plate. The curve 20c oscillates around the mean plane 32 and therefore influences all the channels.

[0052] The other curve followed by each fin of the passage channels 110 is included in a plane comprising the direction axis of each passage channel 110.

[0053] There figure 4 represents a heat exchanger 200 according to one embodiment of the invention. The heat exchanger comprises four passage paths, two passage paths 210a and 210b being intended for a first fluid and two passage paths 220a and 220b intended for a second fluid.

[0054] The passageways are arranged alternately so as to allow heat exchange between the first and second fluids. In this embodiment, the passageways are arranged so that the circulation axes are substantially perpendicular, so as to form a cross-pass exchanger.

Claims

1. Heat exchanger that is configured to permit an exchange of heat between a first fluid and a second fluid that circulate in at least a first passage path and a second passage path, respectively, said passage paths (30, 210a, 210b, 220a, 220b) being formed by plates (14a, 14b, 114) and fins (16a, 16b, 116) of the heat exchanger and being configured to conduct each fluid from a fluid inlet to a fluid outlet, the fluids flowing in a multitude of passage channels (10, 110) each consisting of a closed space (12) delimited by two adjacent plates and two adjacent fins, each plate extends along a non-planar surface defined between the fluid inlet and the fluid outlet of the associated passage path, said non-planar surface following at least one first oscillating curve (20a) along at least one first main direction around an average surface of the plate, each fin comprises an upper edge configured to be in contact with one of the adjacent plates, called upper plate, and a lower edge configured to be in contact with the other adjacent plate, called lower plate, each fin further following at least one second oscillating curve (20b) in at least one second main direction around an average surface of the fin, so that each passage path allows the fluid to flow in the closed space along a fluid direction between the fluid inlet and the fluid outlet, called the flow axis (18, 118), defined at any point of the curve by a generatrix that is a combination at each point at least of the first oscillating curve and of the second oscillating curve, characterized in that the flow axes of the channels of the first passage being substantially orthogonal to the flow axes of the channels of the second passage.

2. Heat exchanger according to claim 1, characterized in that the first curve (20a) and the second curve (20b) have the following characteristics: - 0.1 < γ < 1 - 0.2 < ε < 5 with γ being equal to the mean amplitude of the curve divided by the mean period of the curve, and ε being equal to the mean pitch of the curve divided by the amplitude of the curve.

3. Heat exchanger according to one of claims 1 or 2, characterized in that the first curve (20a) and / or the second curve (20b) is continuous.

4. Heat exchanger according to one of claims 1 or 2, characterized in that the first curve (20a) and / or the second curve (20b) is discontinuous.

5. Heat exchanger according to one of claims 1 to 4, characterized in that the first curve (20a) and / or the second curve (20b) are oscillating with variable amplitude and / or frequency.

6. Heat exchanger according to one of claims 1 to 5, characterized in that the fluids are gaseous or liquid.

7. Heat exchanger according to one of claims 1 to 6, characterized in that it is produced by additive manufacturing.

8. Air conditioning system, characterized in that it comprises a heat exchanger (200) according to one of claims 1 to 7.

9. Aircraft, characterized in that it comprises a heat exchanger (200) according to one of claims 1 to 7.

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