Heat exchanger with a double semi-helical deflector

Abstract

Heat exchanger (1) comprising a heat exchanger body (2) and a separating wall (21) separating a first channel network (22) for the circulation of a first fluid (A) from a first inlet (32) to a first outlet (42), and a second channel network (23) for the circulation of a second fluid (B) from a second inlet (43) to a second outlet (33), characterized in that it further comprises a first deflector (24) comprising a first semi-helical deflector wall, arranged inside the channels of the first channel network (22) and adapted to guide the circulation of the first fluid (A) along a first helical path, and a second deflector (25) comprising a second semi-helical deflector wall, arranged inside the channels of the second channel network (23) and adapted to guide the circulation of the second fluid (B) along a second helical path. Figure for the summary: Fig. 2

Description

Title of the invention: Heat exchanger with a double semi-helical deflector technical field

[0001] This disclosure relates to the general field of heat exchangers. STATE OF THE ART

[0002] Heat exchangers are devices designed to transfer heat between two fluids (liquids or gases) without them mixing. The two fluids flowing through the heat exchanger are separated by a solid wall through which the heat transfer takes place. Such devices are used in various industrial systems, such as power plants, heating, ventilation, and air conditioning systems, and in the chemical industry. Different types of heat exchangers can be used.

[0003] The sizing of heat exchangers takes into account the thermal requirements, that is, the amount of heat to be transferred between the two fluids, based on the desired inlet and outlet temperatures for each fluid. The characteristics of the fluids, in particular their flow velocity, viscosity, and corrosivity, must also be considered when choosing the appropriate type of heat exchanger. The efficiency of heat exchangers depends primarily on the contact area or heat exchange surface of the wall separating the fluids, and on the choice of materials used. Furthermore, it is crucial to consider the pressure losses generated by the flow of fluids through the heat exchanger, as excessive pressure losses could necessitate more powerful pumps to move the fluids, thus increasing energy and economic costs for users.

[0004] In plate heat exchangers, deflectors are used to divert fluid flows, limit dead zones, and ensure proper fluid distribution throughout all channels. This leads to increased performance but also to significant pressure losses and inhomogeneous flow velocities, making these devices inefficient and bulky.

[0005] Depending on the user's needs, an alternative to plate heat exchangers is to use shell and tube (or “shell and tube”) heat exchangers. These are cylindrical exchangers comprising a helical wall and straight tubes extending parallel to the axis of the helical wall and passing through the helical wall. A first fluid flows through the heat exchanger, guided by the helical wall, along a helical path, while a second The fluid flows through straight tubes. Such a heat exchanger is described, for example, in CN101363694A. The use of a helical wall limits the volume occupied by the first fluid in the exchanger, thus increasing its velocity and consequently the heat transfer with the second fluid. However, it is not possible to control the flow velocity of the second fluid in this device with baffles, as the cross-sectional area of ​​the second fluid is constrained by the dimensions of the tubes.

[0006] Recent advances in additive manufacturing methods have made it possible to consider using separating walls generated by triply periodic minimal surfaces, in order to maximize the exchange surface area while reducing the amount of material used. However, heat exchangers incorporating such a separating wall do not allow for sufficiently precise control of increases or decreases in fluid velocities within the heat exchanger. Description of the invention

[0007] One purpose of the present disclosure is to propose a compact heat exchanger with a large exchange surface area while limiting pressure losses, and allowing independent control of fluid velocities in the exchanger.

[0008] This goal is achieved by a heat exchanger comprising a heat exchanger body, the heat exchanger body comprising a first fluid inlet, a second fluid inlet, a first fluid outlet and a second fluid outlet;and a separating wall separating a first network of channels for the circulation of a first fluid from the first inlet to the first outlet, and a second network of channels for the circulation of a second fluid from the second inlet to the second outlet, the heat exchanger being characterized in that it further comprises a first deflector including a first semi-helical deflector wall, arranged inside the channels of the first network of channels and adapted to guide the circulation of the first fluid along a first helical trajectory, and a second deflector including a second semi-helical deflector wall, arranged inside the channels of the second network of channels and adapted to guide the circulation of the second fluid along a second helical trajectory.

[0009] The use of helical deflectors increases the velocity of each of the two fluids in the heat exchanger, thus increasing heat transfer. The heat exchanger can therefore be more compact, while maintaining the same performance. It allows for the processing of very low-velocity fluids or fluids with very different velocities, for example, between a hot first fluid and a cold second fluid, by utilizing the entire available volume. Indeed, in many cases, it is not possible to increase the cross-sectional area of ​​the heat exchanger, particularly its width and / or height. of the heat exchanger, without drastically reducing fluid velocities and therefore the heat transfer coefficient. The use of helical deflectors ensures a certain velocity even when the heat exchanger cross-section is large.

[0010] The helical shape avoids the creation of significant pressure losses, unlike the deflectors used for plate heat exchangers, in which the reversal of the fluid causes significant "shearing" of the fluid which implies unnecessary pressure losses, which are avoided in the proposed solution.

[0011] Each deflector can be integrated independently into each channel network without impacting the fluid flow in the other channel network. The use of semi-helical deflectors allows for independent modulation of the cross-sectional area of ​​each fluid passing through the heat exchanger. The proposed heat exchanger thus offers a balance between a good heat transfer coefficient, a large exchange surface area, and an acceptable pressure drop.

[0012] The invention is advantageously complemented by the following features, taken individually or in any of their technically possible combinations:

[0013] - the first semi-helical deflector wall has a principal axis, and the second The semi-helical deflector wall has the main axis as its axis;

[0014] - the first semi-helical deflector wall is oriented in a first winding direction around the main axis, and the second semi-helical deflector wall is oriented in a second winding direction around the main axis, the second winding direction being opposite to the first winding direction;

[0015] - the first semi-helical deflector wall has a first step, and the the second semi-helical deflector wall has a second pitch, the second pitch being different from the first pitch;

[0016] - the first semi-helical deflector wall has a first axis and extends over a first length along the first axis, and the first semi-helical deflector wall has a first pitch which varies along the first axis over the first length;

[0017] - the second semi-helical deflector wall has a second axis and extends over a second length along the second axis, and the second semi-helical deflector wall has a second pitch which varies over the second length;

[0018] - the separating wall comprises a lattice structure, so that the first the channel network and the second channel network are nested within each other;

[0019] - the separating wall has a triply periodic minimum surface, by example in the shape of a gyroid;

[0020] - the heat exchanger body is cylindrical in shape extending between a first base and a second base, and the first input and second output are arranged on the first base, the first output and second input being arranged on the second base;

[0021] - the separating wall, the first semi-helical deflector wall and the second The semi-helical deflector wall is obtained by an additive manufacturing process. DESCRIPTION OF THE FIGURES

[0022] Other features, objectives and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:

[0023] Fig. 1 is an exploded view of a heat exchanger according to one embodiment.

[0024] Figure 2 is a cross-sectional view of the heat exchanger body of the heat exchanger. [Fig.l].

[0025] Fig. 3 is a cross-sectional view of the deflectors of the heat exchanger body of Fig. 2.

[0026] Fig. 4 is a side view of two semi-helical deflectors of different pitches.

[0027] Figure 5 is a cross-sectional view of a heat exchanger body with pitch deflectors variables.

[0028] Fig. 6 is a side view of the semi-helical deflectors of Fig. 5.

[0029] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION

[0030] The heat exchanger 1 shown comprises a heat exchanger body 2 and collectors 3,4.

[0031] Structure of the heat exchanger

[0032] In the embodiment illustrated in [Fig. 1], the heat exchanger body 2 is delimited by a cylinder of revolution. The cylinder of revolution has a Z-axis of revolution. The cylinder comprises a cylindrical surface and two transverse faces 7 and 8, each extending in a plane orthogonal to the Z-axis, forming a first base 7 and a second base 8 of the cylindrical surface.

[0033] The heat exchanger body 2 comprises a separating wall 21 separating a first channel network 22 for the circulation of a first fluid A from a first inlet to a first outlet, and a second channel network 23 for the circulation of a second fluid B from a second inlet to a second outlet. All the channels of the first channel network 22 communicate with each other. All the channels of the second channel network 23 communicate with each other. However, the channels of the first channel network 22 do not communicate with the channels of the second network of 23 channels, so that the fluids flowing in the two networks do not mix.

[0034] In the embodiment of [Fig. 1], the first face or base 7 constitutes an inlet surface for the first fluid A and an outlet surface for the second fluid B. The second face or base 8 constitutes an outlet surface for the first fluid A and an inlet surface for the second fluid B, opposite to their respective inlet and outlet surfaces.

[0035] The exchanger body 2 further comprises a first inlet wall 71 and a second inlet wall 83, a first outlet wall 81 and a second outlet wall 73.

[0036] The first inlet wall 71 and the first outlet wall 81 close off the channels of the second channel network 23 opening onto the first face 7 and the second face 8.

[0037] Similarly, the second inlet wall 81 and the second outlet wall 71 close the channels of the first channel network 22 opening onto the first face 7 and the second face 8.

[0038] For this purpose, the first inlet wall 71 has a series of openings 72 arranged so as to allow the first fluid to circulate through the first face 7. The first inlet wall 71 allows the first fluid A to penetrate through the first face 7 into the first channel network 22 while preventing the first fluid from penetrating through the first face 7 into the second channel network 23.

[0039] The first outlet wall 81 has a series of outlet openings 82 arranged to allow circulation of the first fluid through the second face 8. The first outlet wall 81 allows extraction of the first fluid A through the second face 8 out of the first channel network 22, while prohibiting extraction of the second fluid B through the second face 8 out of the second channel network 23.

[0040] Thus, the first fluid A enters the inside of the exchanger body 2 via the first inlet wall 71, circulates in the channels of the first channel network 22, and exits the exchanger body 2 via the first outlet wall 81.

[0041] Similarly, the second inlet wall 83 has a series of openings 82 arranged so as to allow circulation of the second fluid B through the second face 8. The second inlet wall 83 allows penetration of the second fluid B through the second face 9 into the second channel network 23, while prohibiting penetration of the second fluid B through the second face 9 into the first channel network 22.

[0042] The second outlet wall 73 has a series of outlet openings 72 arranged so as to allow circulation of the second fluid B through the first face 7. The second outlet wall 73 permits extraction of the second fluid B through the first face 7 out of the second channel network 23, while prohibiting extraction of the first fluid A through the first face 7 out of the first channel network 22.

[0043] Thus, the second fluid B enters the inside of the exchanger body 2 via the second face 8, circulates in the channels of the second channel network 23, and exits the exchanger body 2 via the first face 7.

[0044] The collectors 3,4 include a first collector 3, and a second collector 4.

[0045] The first collector 3 is suitable for guiding the first fluid A (for example a cold fluid) so that the first fluid circulates inside the heat exchanger body 2 in the first network of channels 22.

[0046] The first manifold 3 forms an upper end plate. It is fixed to the first face 7 of the heat exchanger body 2. The first manifold 3 comprises a wall 31, a first inlet pipe 32 suitable for connection to a first supply pipe of the first fluid A, and a second outlet pipe 33 suitable for connection to a second outlet pipe of the second fluid B.

[0047] Similarly, the second collector 4 is suitable for guiding the second fluid B (for example a hot fluid) so that the second fluid B circulates inside the exchanger body 2 in the second network of channels 23.

[0048] The second manifold 4 forms a lower end plate. It is fixed to the second face 8 of the heat exchanger body 2. The second manifold 4 comprises a wall 41, a first outlet pipe 42 suitable for connection to a first extraction duct of the first fluid, and a second inlet pipe 43 suitable for connection to a second supply duct of the second fluid B.

[0049] The heat exchanger 1 also includes a plurality of closing walls 9,10,11,12 extending around the periphery of the exchanger body 2 so as to close both the channels of the first channel network 22 and the channels of the second channel network 23.

[0050] The heat exchanger 1 further comprises an external casing or shell 16 surrounding the heat exchanger body 2. The shell 16 comprises a wall 161 of generally cylindrical shape. The wall 161 of the shell 16 surrounds the heat exchanger body 2 and the closure walls 9, 10, 11, 12. The wall 161 of the shell 16 can be fixed to the closure walls 9, 10, 11, 12, for example by weld lines.

[0051] The first end plate or collector 3 is fixed to the shell 16, for example by a weld line, so as to extend opposite the first face or base 7 of the heat exchanger body 2.

[0052] The second end plate or collector 4 is fixed to the shell 16, for example by a weld line, so as to extend opposite the second face or base 8 of the heat exchanger body 2.

[0053] During operation, the first fluid A is injected into the heat exchanger 1 via the first inlet pipe 32 of the first manifold 3. The first fluid A enters the heat exchanger body 2 by passing through the first fluid inlet wall 71 into the first channel network 22. The first fluid A flows through the first channel network 22 and exits the heat exchanger body 2 by passing through the first fluid outlet wall 81. The first fluid A is extracted from the heat exchanger 1 via the first outlet pipe 42 of the second manifold 4.

[0054] The second fluid B is injected into the heat exchanger 1 via the second inlet pipe 43 of the second manifold 4. The second fluid B enters the heat exchanger body 2 by passing through the second fluid inlet wall 83 into the second channel network 23. The second fluid B circulates in the second channel network 23 and exits the heat exchanger body 2 by passing through the second fluid outlet wall 73. The second fluid B is extracted from the heat exchanger via the second outlet pipe 33 of the first manifold 3.

[0055] While the first fluid A and the second fluid B circulate in the heat exchanger body 2, a heat transfer occurs between the fluids through the separating wall 21. The heat exchanger body 2 extends over a height H along the direction of fluid flow carried by the axis Z.

[0056] Semi-helical deflectors

[0057] In order to lengthen the distance traveled by each of the fluids A,B in the body of the exchanger 2, to increase the velocity of the fluids A,B, and thus increase the total heat transfer in the heat exchanger 1, the heat exchanger has the particularity that it includes a first deflector 24 arranged in the first network of channels 22 so as to deflect the circulation of the first fluid A, and a second deflector 25 arranged in the second network of channels 23 so as to deflect the circulation of the second fluid B.

[0058] More specifically, the first deflector 24 comprising a first semi-helical deflector wall, arranged inside the channels of the first channel network 22 and adapted to guide the circulation of the first fluid A along a first helical trajectory.

[0059] The first deflector 24 does not interfere with the second channel network 23 and therefore does not alter the trajectory of the second fluid B. In other words, the first deflector wall comprises a plurality of wall elements arranged in the first channel network 22 along a helical virtual surface, so as to obstruct channels of the first channel network 22, but does not comprise any elements

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066] in the second channel network 23. This allows the flow of the first fluid A to be diverted independently of the flow of the second fluid B, the second fluid not being in contact with the first deflector 24 when it flows through the exchanger body 2. Similarly, the second deflector 25 comprises a second semi-helical deflector wall, arranged inside the channels of the second channel network 23 and designed to guide the flow of the second fluid B along a second helical path. The second helical path is distinct from the first helical path. The second deflector wall comprises a plurality of wall elements arranged in the second channel network 23 along a helical virtual surface, so as to obstruct channels in the second channel network 23, but does not include any elements in the first channel network 22. This allows the flow of the second fluid B to be diverted independently of the flow of the first fluid A, the first fluid A not being in contact with the second deflector 25 when it flows through the exchanger body 2. The semi-helical shape of the walls of the first deflector 24 and the second deflector 25 advantageously reduces the impact of the deflectors 24,25 on the velocity gradient of the fluids in the respective channel networks 22,23, and thus avoids a deceleration of the fluids A,B. It also allows the flow of fluids A,B to be accelerated in a controlled manner. The helical virtual surface in which the wall elements of the first deflector wall and the second deflector wall are arranged is mathematically described in the three-dimensional space formed by the exchanger body 2 by the following parametric equation: x ( u ) = Rco^u) y(u) = RE sin(i / ) z(«) =cu -c tarr'l where R is the radius of the first or second base 7,8 of the cylinder formed by the exchanger body 2, u is a parameter, etc. is a constant such that 2^c is the pitch of the helical virtual surface along the principal axis Z, and therefore the pitch of the corresponding deflector. The orientation parameter μ = 1 is also defined for a helical virtual surface rotating in the clockwise direction, and μ = -1 for a helical virtual surface rotating in the counterclockwise direction. Additionally, in an embodiment where the calender is not cylindrical, the radius R can vary. For example, the radius R can vary along The main Z axis, between the first fluid inlet and the first fluid outlet. This allows the deflector to be adapted to the geometry of the grille.

[0067] To obtain a half-helix, the parameter u extends over an interval of length ji, for example over the interval [0, 1]. This allows the wall elements of the corresponding deflector 24, 25 to be located not directly at the inlet or outlet in the heat exchanger body 2, particularly in an embodiment where the respective inlets and outlets are not aligned along the direction of the Z-axis, as shown. Unlike a surface forming a complete helix, the use of a half-helix surface avoids dividing the volume of the heat exchanger 1 into two separate spaces for each channel array 22, 23. Thus, the volume delimited by each channel array 22, 23 can be fully utilized; that is, the fluids A, B are deflected and occupy all the available space within the shell 16 as they pass through the heat exchanger 1.

[0068] The system of equations given above allows us to define a semi-helical deflector wall extending around the Z axis. More generally, the first deflector 24 and / or the second deflector 25 can extend around a principal axis distinct from the Z axis, typically an axis parallel to the Z axis, or even with an axis aligned with the outlet tubes 33,42 or the inlet tubes 32,43.

[0069] Preferably, the first semi-helical deflector wall has a principal axis, and the second semi-helical deflector wall has the principal axis as its axis. In the illustrated embodiment, the principal axis is the Z-axis. According to another, unillustrated embodiment, the first semi-helical deflector wall may have a principal axis orthogonal to the principal axis of the second semi-helical deflector wall. Such a configuration can be adapted to the environment in which the heat exchanger 1 is integrated, particularly in the context of a counter-flow (or "cross-flow" heat exchanger, according to commonly used English terminology) exchanger.

[0070] The first half-helical deflector wall 24 is characterized by the first orientation parameter i, and the second half-helical deflector wall 25 is characterized by the second orientation parameter. The first and second orientation parameters may have the same value. In this case, the two helical shapes are oriented in the same direction, and the two fluids rotate in the same direction within the heat exchanger body 2.

[0071] Preferably, the first semi-helical deflector wall is oriented in a first winding direction around the principal axis Z, and the second semi-helical deflector wall is oriented in a second winding direction around the principal axis Z, the second winding direction being opposite to the first winding direction. In other words, the first and second orientation parameters are opposite. For example, we have = 1 for the first wall of the semi-helical deflector, and £? = ~ 1 for the second wall of the semi-helical deflector.

[0072] Thus, the first fluid A rotates in a first direction of rotation, while the second fluid B rotates in a second direction of rotation opposite to the first direction of rotation. The deflection induced by the respective deflectors 24, 25 increases the surface area of ​​the separating wall 21 where the fluids A and B cross counter-currently by increasing the distance traveled by the fluids A and B within the heat exchanger 1, and thus increases the thermal performance of the heat exchanger 1. In other words, to force the flows of fluids A and B to be completely opposite and in opposite directions, it is possible to change the direction of rotation of the coil by changing the sign of the orientation parameter e. Therefore, a clockwise or counter-clockwise upward / downward direction is possible.

[0073] The first semi-helical deflector wall has a first pitch PI, and the second semi-helical deflector wall has a second pitch P2. Preferably, the first pitch Pi = 2irci and the second pitch P2 = 2irc2 are different. Using different pitches for the two fluids is particularly advantageous when the first fluid A and the second fluid B have different physical properties. Indeed, the velocity of the fluid deflected by a semi-helical deflector with a reduced pitch is considerably increased, for a constant inlet flow rate, because the cross-sectional area is reduced. The fluid is thus accelerated and travels a greater distance for the same transit time through the heat exchanger 1.Conversely, using a larger step size does not significantly increase the distance traveled by the fluid, and therefore has a smaller impact on the change in fluid velocity during its flow in the exchanger body 2.

[0074] More generally, it is advantageous to use a different deflector in each independent channel network 22, 23. This allows for precise control of the relative velocity between the first fluid A flowing in the first channel network 22 and the second fluid B flowing in the second channel network 23 of the heat exchanger 1, thereby increasing its thermal performance. Indeed, this allows for very precise control of the local heat transfer coefficient within the heat exchanger body 2 by locally modifying the fluid velocity, since the velocity of each fluid can be different in each channel of the channel network 22, 23. Depending on the first and second pitches chosen, the first fluid A will perform a number of passes or rotations X when the second fluid performs a number of rotations Y, with X less than, equal to, or greater than Y, depending on the relative pitch values.

[0075] The free choice of the pitches P1,P2 of the first deflector wall and the second deflector wall, respectively, is an important advantage because the overall heat transfer coefficient can be expressed as the combination of the different heat transfer coefficients Local resistances depend on the heat transfer coefficient of the external and internal films (i.e., for each of the fluids), or the heat transfer coefficient. By changing the fluid velocity, it is possible to significantly increase its heat transfer coefficient and therefore increase the overall heat transfer coefficient without affecting the other fluid, i.e., without excessive pressure drop. This allows for a more precise determination of the desired overall heat transfer coefficient and thus for better sizing of the heat exchanger 1.

[0076] Preferably, the first step Pi is at least twice greater than the second step P2. However, this example is not limiting; the ratio between the first step Pi and the second step P2 can be easily adapted to the properties of fluids A, B.

[0077] An example of a heat exchanger 1 for an asymmetric flow is as follows: the first fluid A is a hot mixture of an aqueous liquid and a gas, with a density of 860 kg / m³, an inlet temperature of 156°C, and a pressure of 80 bar, and the second fluid B is cold water, with an inlet temperature of 40°C and a pressure of 5 bar. The flow rate of the first fluid A is 44 kg / h, which is much lower than the flow rate of the second fluid B, which is 1393 kg / h. Thus, the first fluid A is significantly cooled during its passage through the heat exchanger, and has an outlet temperature of 50°C, while the second fluid B does not undergo a significant temperature change, and has an outlet temperature of 44°C.

[0078] Since the first channel network 22 is independent of the second channel network 23, it is possible to use nested deflector walls 24, 25 with different pitches, as the nested surfaces only interfere with the flow of fluid within their respective channel networks. An example embodiment will be detailed later.

[0079] With reference to Figures 5 and 6, the first semi-helical deflector wall 24 may have a pitch that varies with height. In other words, the first semi-helical deflector wall has a first axis Z and extends over a first length along the first axis Z, and the first semi-helical deflector wall has a first pitch that varies along the first axis over the first length. In this case, it is characterized by a function c^z) varying along the Z axis.

[0080] Alternatively or complementarily, the second semi-helical deflector wall 25 can have a pitch that varies with height and be characterized by a function c^z. In other words, the second semi-helical deflector wall has a second axis Z' and extends over a second length along the second axis Z', and the second semi-helical deflector wall has a second pitch that varies over this second length. This allows for precise control of the relative velocity between the inlet and outlet of the heat exchanger 1 and increases its performance. Thermal. This allows the apparent cross-sectional area along the path of fluid A,B within the heat exchanger body 2 to be varied, and therefore the velocity of fluid A,B as it passes through heat exchanger 1 to be varied. Indeed, by decreasing the pitch of the half-helix, the cross-sectional area of ​​the fluid passage will be smaller and therefore the fluid will accelerate. Conversely, by increasing the pitch, the cross-sectional area of ​​the fluid passage will be larger and therefore the fluid will slow down.

[0081] This is particularly advantageous in the case of evaporation or condensation of fluid A,B taking place inside the heat exchanger 1. This makes it possible to compensate for the evolution of the physical properties of fluid A,B in a localized way, and thus limit pressure losses and / or increase the exchange coefficient.

[0082] For example, the pitch p1(z) increases between the first fluid inlet 32 ​​and the first fluid outlet 42. This is suitable in the case of expansion of the first fluid A along its path in the heat exchanger. Alternatively, the pitch pl(z) decreases between the first fluid inlet 32 ​​and the first fluid outlet 42. This is suitable in the case of contraction of the first fluid A along its path in the heat exchanger, due to cooling.

[0083] The pitch p2(z) of the second deflector wall can also be constant, increasing, or decreasing between the second fluid inlet 43 and the second fluid outlet 33.

[0084] The use of a variable step size pl(z),p2(z) is particularly advantageous when a change of state of the respective fluid occurs within the heat exchanger 1. Indeed, this makes it possible to reduce or increase the flow area depending on the evaporation (liquid-to-vapor transition), and therefore expansion, or condensation (vapor-to-liquid transition), and therefore compression, of fluid A,B, and to more precisely control the velocity of fluid A,B. In fact, during heat exchange, the properties of fluid A,B change depending on the temperature and pressure. For example, they can occupy more or less volume in the case of evaporation or condensation. Thus, it is sometimes necessary to accelerate fluid A,B (in the case of condensation, for example) or to slow it down (in the case of evaporation) to optimize heat exchange and / or pressure drop.

[0085] In one embodiment, the first and second walls of the semi-helical deflector 24, 25 may have different pitches and opposite directions of rotation. Thus, the flow will be different between the two fluids A, B. This embodiment can be used to modify the heat transfer by locally changing the crossing of fluids A, B.

[0086] The thickness of the first deflector wall can be constant or variable depending on the height along the first Z axis. This also allows modification of the passage cross-section of the first fluid A through the exchanger body 2.

[0087] Alternatively or complementaryly, the thickness of the second deflector wall can be constant or variable depending on the height along the second axis. This also allows modification of the cross-sectional area through which the second fluid B passes through the heat exchanger body 2.

[0088] Lattice structure

[0089] As explained previously, the presence of a separating wall 21 defining two distinct and independent channel networks is necessary for the use of two half-helical deflector walls 24, 25. Typically, the heat exchanger body 2 incorporates a lattice structure. In other words, the separating wall includes a lattice structure, such that the first channel network and the second channel network are nested within each other. Thus, it is possible to define the deflectors 24, 25 only within their respective channels, which allows the first channel network 22 and the second channel network 23 to be modified independently.

[0090] Preferably, the separating wall 21 has a triply periodic minimal surface (TPMS). Such a surface allows the two distinct and constantly contacted channel networks to be separated, thereby increasing the contact area and thus the heat transfer for a given volume. The heat exchanger 21 can thus be both compact and efficient. A separating wall 21 defined in this way minimizes the average local curvature and therefore prevents undesirable pressure losses or pressure drops.

[0091] Various three-periodic structures can be used to define the separating wall 21. Among others, the Schwarz-P surface, defined by the equation, can be cited for example:

[0092] fSP(x,y,z) = cos (x) + cos (y) + cos (z) = K, with K a constant,

[0093] or the Schwarz-D surface defined by the equation:

[0094] fSD(x,y,z) = cos (x) cos (y) cos (z) - sin (x) sin (y) sin (z) = K, with K constant.

[0095] In another embodiment, the separating wall 21 is gyroid-shaped. The The gyroid shape of the separating wall 21 allows to maximize the exchange surface between the two fluids, while limiting pressure losses.

[0096] In the case of the heat exchanger body 2 illustrated in [Fig.2], the gyroid is a three-dimensional curve, defined by the equation:

[0097] fG(x,y,z) = ax cos (x) x sin (y) + bx cos (y) x sin (z) + cx cos (z) x sin (x) = K,

[0098] with a, b and c non-zero coefficients, and K a constant. For example, each of the coefficients a, b and c is equal to 1.

[0099] In these three examples, the separating wall 21 is, for example, delimited between an upper surface with equation f(x,y,z) = K, and a lower surface with equation f (x,y,z) = -K, with K constant. The separating wall 21a then has a thickness equal to 2K.

[0100] The Schwarz-P surface-shaped separation wall 21 exhibits higher permeability and a lower drag coefficient than other surfaces, for the same deflector wall thickness. However, this surface shape also has a higher friction coefficient, resulting in lower fluid velocities in the heat exchanger. The Schwarz-D surface-shaped separation wall 21 allows for a higher energy density for high-density fluids and improved heat transfer efficiency in laminar flow regimes, and exhibits good convection properties. The choice of the separation wall shape 21 may also depend on the Reynolds number of the fluid flow in the heat exchanger 1, and therefore on the density and viscosity of the fluids A, B used.The size of the cells forming each of the channel networks can be adapted to reduce the fluid pressure gradient in their respective channels. The gyroid-shaped separator wall 21 offers a good compromise for flows with a higher Reynolds number (Re > 75) and for thicker walls.

[0101] In particular, the gyroid-shaped separating wall 21 can have a variable thickness depending on the flow direction or the direction along the Z-axis. The above equation can be modified so that the cross-section of the channels in each channel network 22, 23 varies independently along a direction. In this case, the separating wall satisfies the equation

[0102] F (x, y, z) + ax cos (x) x sin (y) + bx cos (y) x sin (z) + cx cos (z) x sin (x) = K

[0103] where F is a function such that for fixed x and y, F is strictly monotonic. F is considered strictly monotonic if, for all zl < z2, F(zl) < F(z2), or for all zl < z2, F(zl) > F(z2), in the volume occupied by the heat exchanger body. Typically, the function F can be a linear function of x, y, and / or z, for example of the form:

[0104] F(x, y, z) = Axx + Bxy + Cxz

[0105] where A, B, and C are predefined coefficients, of which at least the coefficient C is non-zero. As before, the separating wall 21 can be delimited between an upper surface with equation fG(x,y,z) = K - F(x,y,z), and a lower surface with equation fG(x,y,z) = -K - F(x,y,z), with K constant. The separating wall 21 has a thickness equal to 2K, the upper and lower surfaces extending in parallel.

[0106] Similarly, the separating wall 21 in Schwarz-G or Schwarz-P shape can have a variable thickness by modifying the corresponding equation in a similar way.

[0107] The plurality of wall elements of the first deflector 24 are inserted into the first channel network 22 formed by the separating wall 21, and the plurality of wall elements of the second deflector 25 are inserted into the second channel network 23. For this purpose, the plurality of wall elements may have a shape complementary to the geometry of the respective channel networks.

[0108] As can be seen in [Fig. 3], in which the separating wall 21 is not shown, and in [Fig. 4], the first deflector 24 and the second deflector 25 are supported by the helical virtual surface and have a perforated structure. In particular, the wall elements of each of the deflectors 24, 25 interlock without touching, in that they are separated by the separating wall 21. The first deflector 24 does not interfere with the second channel array 23, and the second deflector 25 does not interfere with the first channel array 22.

[0109] Other embodiments envisaged

[0110] In an embodiment not covered by the invention, the plurality of wall elements of the first deflector 24 and / or the second deflector 25 can extend along planes. Typically, parallel planes, for example normal to the Z-axis. This also allows the flow of the first (respectively second) fluid to be diverted into the first (respectively second) channel network 22, 23.

[0111] In another embodiment not covered by the invention, the heat exchanger 1 comprises a single deflector arranged in the first channel network 22, so that only the first fluid A is deflected during its circulation in the exchanger body 2 by the single deflector, the second fluid B flowing in the channels of the second channel network 23 between the second fluid inlet 32 ​​and the second fluid outlet 33.

[0112] The present invention is not limited to a cylindrical heat exchanger body 2. In other embodiments, the heat exchanger body 2 could be delimited by a rectangular parallelepiped, for example a cuboid or a cube, having six flat faces or surfaces. In this case, the virtual semi-helical surfaces on which the elements of the first and second semi-helical deflector walls are arranged are truncated to correspond to the dimensions of the heat exchanger body 2.

[0113] Moreover, the present invention is not limited to a counter-current flow as illustrated in [Fig.1].

[0114] Alternatively, the pipe 33 can be an inlet pipe for the second fluid B and the pipe 43 an outlet pipe for the second fluid B. In this embodiment, the deflectors 24, 25 have opposite directions of rotation, so that the fluids A, B flow counter-currently along the separating wall. The position of the fluid inlets 32, 43 and the fluid outlets 42, 33 on the heat exchanger body 2 depends on the integration constraints of heat exchanger 1 and the desired performance.

[0115] Alternatively, the inlet and outlet pipes 33,43 of the second fluid B can be arranged on lateral surfaces of the exchanger body 2. In this embodiment, the second deflector 25 can have a helical shape carried by an axis not extending along the Z axis, for example transverse to the Z axis or passing through the inlet pipe and the outlet pipe.

[0116] The number of turns of the semi-helical shapes of each of the deflectors 24,25 can vary, so that each of the fluids A,B can perform a variable number of rotations within the exchanger body 2.

[0117] The heat exchanger body 2 (including the separating wall 21 and the walls 71, 81, 73, 83) can be formed in a single piece of material, by an additive manufacturing technique or by a casting technique.

[0118] Preferably, the separating wall, the first half-helical deflector wall, and the second half-helical deflector wall are obtained by an additive manufacturing process. The additive manufacturing technique may be a powder bed additive manufacturing technique (for example, a selective laser melting technique – called SLM or “Selective Laser Melting” in English), or a powder or wire deposition additive manufacturing technique (for example, a directed energy deposition technique – called DED or “Directed Energy Deposition” in English), or a wire and laser additive manufacturing technique (called WLAM or “Wire and Laser Additive Manufacturing”).The heat exchanger body 2 can also be obtained by a strip or thin sheet welding process, for example the AMW (“Additive Micro Welding”) process offered by INETYX ® based on the principle of micro-welding metal strips layer by layer.

[0119] The additive manufacturing process advantageously allows the simultaneous production of the separating wall 21 forming the body of the exchanger 2 and the wall elements following the helical shape of each of the deflectors 24,25.

[0120] The material of the heat exchanger body 2 may be a material with good thermal conductivity, that is to say, a thermal conductivity typically between 100 and 400 W / mK (watts per meter-kelvin). However, the material used may have lower thermal conductivity, for example between 10 and 100 W / mK, but have mechanical properties suitable for use as a heat exchanger, that is to say, resist the fluids present, in particular resist corrosion.

[0121] The material is preferably a metal, for example titanium, or a metal alloy, for example carbon steel (i.e. a steel whose main alloying component is carbon with a content of between 0.12 and 2.0%, other alloying elements being in very small quantities) or an austenitic steel (i.e. a steel characterized by a face-centered cubic molecular structure, such as stainless steel obtained with 18% chromium and 8% nickel), or a duplex steel (i.e. a stainless steel having a two-phase structure composed of ferrite complemented by 40 to 60% austenite, and typically containing at least 20% chromium, nickel, molybdenum, nitrogen and optionally copper and / or tungsten) or a super duplex steel (typically containing between 25% and 30% chromium, between 6 and 8% nickel, molybdenum, nitrogen and optionally copper and / or tungsten) or even an alloy based on nickel, aluminum or titanium. Alternatively, the material of the exchanger body 2 can be a polymer, a mixture of polymers or a composite material (e.g. a filled polymer).Preferably, the material used is stainless steel (i.e., steel containing less than 1.2% carbon and more than 10.5% chromium). This material has good mechanical properties, is relatively inexpensive and widely available, which facilitates the production of heat exchanger 1.

[0122] The present invention can advantageously be used in a set of heat exchangers. To this end, a variable number of heat exchangers 1 can be stacked according to requirements. In this case, the first face or upper face 7 of a heat exchanger is connected to the second face or lower face 8 of another adjacent heat exchanger in the stack so that the first fluid A and the second fluid B flow successively through the heat exchangers of the stack.

Claims

Demands

1. Heat exchanger (1) comprising a heat exchanger body (2), the heat exchanger body (2) comprising a first fluid inlet (32), a second fluid inlet (43), a first fluid outlet (42) and a second fluid outlet (33), and a separating wall (21) separating a first channel network (22) for circulation of a first fluid (A) from the first inlet (32) to the first outlet (42), and a second channel network (23) for circulation of a second fluid (B) from the second inlet (43) to the second outlet (33), the heat exchanger (1) being characterized in that it further comprises a first deflector (24) comprising a first semi-helical deflector wall, arranged inside the channels of the first channel network (22) and adapted to guide the circulation of the first fluid (A) along a first helical path,and a second deflector (25) comprising a second semi-helical deflector wall, arranged inside the channels of the second channel network (23) and adapted to guide the flow of the second fluid (B) along a second helical trajectory.

2. Heat exchanger according to claim 1, wherein the first semi-helical deflector wall has a principal axis (Z), and wherein the second semi-helical deflector wall has the principal axis (Z) as its axis.

3. Heat exchanger according to claim 2, wherein the first semi-helical deflector wall is oriented in a first winding direction around the main axis (Z), and wherein the second semi-helical deflector wall is oriented in a second winding direction around the main axis (Z), the second winding direction being opposite to the first winding direction.

4. Heat exchanger according to any one of claims 1 to 3, wherein the first semi-helical deflector wall has a first pitch (PI), and wherein the second semi-helical deflector wall has a second pitch (P2), the second pitch (P2) being different from the first pitch (PI).

5. Heat exchanger according to any one of claims 1 to 4, wherein the first semi-helical deflector wall has a first axis (Z) and extends over a first length (H) along the first axis (Z), and the first semi-helical deflector wall has a first pitch (pl(z)) which varies along the first axis (Z) over the first length (H).

6. Heat exchanger according to any one of claims 1 to 5, wherein the second semi-helical deflector wall has a second axis (Z) and extends over a second length (H) along the second axis (Z), and the second semi-helical deflector wall has a second pitch (p2(z)) which varies over the second length.

7. Heat exchanger according to any one of claims 1 to 6, wherein the separating wall (21) comprises a lattice structure, such that the first channel network (22) and the second channel network (23) are nested within each other.

8. Heat exchanger according to any one of claims 1 to 7, wherein the separating wall (21) has a triply periodic minimum surface, for example in the shape of a gyroid.

9. Heat exchanger according to any one of claims 1 to 8, wherein the exchanger body (2) is cylindrical in shape extending between a first base (7) and a second base (8), and wherein the first inlet (32) and the second outlet (33) are arranged on the first base, and the first outlet (42) and the second inlet (43) are arranged on the second base (8).

10. Heat exchanger according to any one of claims 1 to 9, wherein the separating wall (21), the first semi-helical deflector wall and the second semi-helical deflector wall are obtained by an additive manufacturing process.

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