Heat exchanger

Abstract

The present invention relates to a heat exchanger (1) for preheating the combustion air of a microturbine in a cogeneration system. The structure of this heat exchanger (1) comprises an assembly of flat distribution frames (31, 31') and spacer metal sheets (32). Each distribution frame is defined by a contour enclosing a fluid zone (80) and is equipped with inlet ports (11) and outlet ports (11) for the passage of this fluid. The metal sheets (32) are supported by support protrusions (4) on the distribution frames (31, 31'), which simplifies the fabrication of the heat exchanger (1).

Description

technical field

[0001] The present invention relates to a "heat exchanger" (also referred to as "exchanger" in this document) for preheating combustion air from a compressor of a micro-turbine of an energy production and / or cogeneration device. Previous art

[0002] A heat exchanger, particularly in cogeneration systems equipped with micro gas turbines, plays a crucial role in improving overall efficiency. Its essential function is to preheat the combustion air by recovering the thermal energy still present in the turbine exhaust gases. For example, such a heat exchanger can be constructed using a conventional structure consisting of an arrangement of heat exchange plates positioned between distribution frames and reinforced by metal mesh inserted into the frames. This configuration facilitates efficient, alternating exchange between hot and cold fluids, thus optimizing heat transfer. However, manufacturing such a heat exchanger can present certain challenges, especially when it comes to producing metal meshes that can take on complex shapes.

[0003] International publication WO 2016 / 124472 A1 presents such a heat exchanger design, integrated into a combined heat and power (CHP) system equipped with a micro gas turbine. Publication WO 2022 / 074078 A1, on the other hand, discloses a heat exchanger in which central leakage zones for leakage fluid are formed within distribution frames. Two adjacent distribution frames are separated by two separating plates, and a leakage passage between these plates is defined by a frame with ribs facing a turbulator to direct any fluid from the leakage zones towards it. The leakage fluid can be discharged through lateral ports in these frames or through specific end inlets and outlets provided in the exchanger. Description of the invention

[0004] One object of this invention is to provide a heat exchanger that is more robust and simpler to manufacture compared to the prior art.

[0005] For this purpose, a heat exchanger is proposed for an energy production and / or cogeneration unit, comprising: a stack of flat distribution frames, each having an internal contour delimiting a hot or cold fluid zone, the fluid zone communicating with fluid inlet and outlet ports, provided in each of the adjacent frames (according to the stacking), the hot and cold fluid zones alternating along a thickness of the exchanger; metal sheets arranged alternately with the distribution frames according to the stacking to create thermal contact between said fluid zones; Each of the distribution frames is provided with support projections extending from the inner contour towards the fluid zone.

[0006] The heat exchanger according to the invention is robust and simpler to manufacture. Indeed, the support projections, which extend from the inner contour of the frames towards the fluid flow zones, act as internal structural support for the metal sheets. By projecting into the fluid flow zones, these projections help maintain the integrity of the sheets against mechanical stresses, particularly against differential pressures between the hot and cold zones.

[0007] Furthermore, integrating the projections directly into the distribution frames can help eliminate the need for additional components such as wire mesh or other forms of external reinforcement. This can simplify the manufacturing process by reducing the number of separate parts to be manufactured and assembled. By reducing the complexity of the components required for heat exchanger assembly, production costs are lowered. Manufacturing becomes more straightforward, enabling standardization, easier logistics, and potential economies of scale during mass production.

[0008] As a skilled professional will understand, the distribution frames, which guide the flow of hot and cold fluids, are arranged to allow for orderly stacking. The metal sheets are placed alternately with these distribution frames so that each metal sheet is positioned between two successive frames. In other words, the heat exchanger stack is designed with an alternating arrangement where each distribution frame (delimiting a zone of hot or cold fluid) is followed by a metal sheet, then by another distribution frame (delimiting a zone of hot or cold fluid), and so on along the thickness of the exchanger. The arrangement of the metal sheets follows this sequence to ensure thermal contact between the alternating zones of hot and cold fluids.

[0009] The term "fluid zone" refers to the region specifically delimited by the inner contour of each distribution frame where hot or cold fluids circulate for heat transfer. Each fluid zone communicates with specific openings that allow fluids to enter and exit. The "inlet ports" allow fluid to enter the fluid zone for heat transfer, and the "outlet ports" allow the fluid to leave the zone after exchanging heat. These ports are integrated or incorporated into the distribution frames, which are positioned side-by-side (i.e., adjacent) within the heat exchanger structure. Each frame has its own ports for fluid passage, allowing continuous circulation with those of neighboring frames throughout the exchanger.

[0010] The use of the verb "comprendre" (to understand), its variants, and its conjugations in this document does not in any way preclude the presence of elements other than those mentioned. Similarly, the use of the indefinite article "un" (a / an) or the definite article "le" (the / it) to introduce an element does not preclude the presence of multiple such elements.

[0011] In a preferred embodiment of the present invention, the projections comprise a plurality of fingers connected to a common base. More precisely, the projections are grouped into sets, each set consisting of a plurality of fingers connected to a common base. Advantageously, the fingers thus add greater robustness to the heat exchanger structure. This projection configuration also increases the support surface area for the metal sheets. The spacing between the fingers is sufficient to allow the circulation of hot and cold fluids. The robustness and efficiency of the exchanger are thereby improved. The fingers preferably have a rectangular cross-section (in their direction of extension) because they are projections originating from a flat frame. The term "fingers" may be substituted for "elongated bodies" or "elongated elements" in this document.

[0012] Preferably, the common base extends from the inner contour into the fluid zone, forming a bridge. This means that the common base connecting the fingers extends from the inner contour, crosses the fluid zone, and reaches the opposite side, thus forming a bridge across this zone. The common base therefore extends into the fluid zone.

[0013] In one embodiment, the fingers are parallel and of equal length. Advantageously, this allows for the uniform distribution of mechanical forces across the metal sheets, reducing the risk of deformation or breakage. It also simplifies the design and manufacture of the distribution frames. Preferably, the fingers are identical.

[0014] In one embodiment, the common base is arranged as a projection of an edge of one of the inlet or outlet ports of one of the adjacent distribution frames in the stack. As those skilled in the art will understand, the common base is preferably, more precisely, an orthogonal projection along the stack (or equivalently along the thickness of the heat exchanger), at the level of the frame in which the projections are located. The common base then provides support to the adjacent distribution frame during the assembly of the heat exchanger, particularly by brazing or diffusion welding as explained below, thereby contributing to improved sealing and robustness of the heat exchanger.

[0015] Alternatively or complementaryly, a portion of each finger is arranged according to such a projection. In other words, preferably, each finger intersects such a projection. The fingers (and in both cases, the projections) support the distribution frames during the assembly of the aforementioned heat exchanger, thereby improving the heat exchanger's sealing and robustness.

[0016] In one embodiment, the fingers extend from the common base into the fluid zone at a normal angle to it. Advantageously, this embodiment ensures that the hot and cold fluid flows are directed more efficiently into and out of the fluid zone. This means that the hot or cold fluid is guided within the fluid zone without unnecessary dispersion that could reduce heat transfer efficiency. This finger configuration also helps stabilize the fluid flow at the inlet and outlet, reducing turbulence that can occur when fluids move from one fluid zone to another. The invention thus enables a more orderly and less resistant fluid path, which can contribute to the overall efficiency of heat exchange.

[0017] In one embodiment, the distribution frames have essentially polygonal shapes. Polygonal shapes are defined as angular forms consisting of a finite sequence of consecutive straight line segments. Advantageously, such a shape offers ease of manufacturing. For example, the distribution frames can incorporate rectangular inlet and / or outlet ports (the term "rectangular" also encompassing "square") and have rectangular internal contours or zigzag shapes. These shapes are simpler to cut and integrate into metal structures than rounded or irregular shapes. This can reduce production costs and simplify the assembly of the heat exchanger components.

[0018] In this case, the common base (preferably of each set of projections as described above) is straight and has parallel fingers of equal length attached to it. This is a particularly simple and robust design in which all frame elements are straight. The mechanical forces are distributed uniformly across the metal sheets thanks to the configuration of the fingers.

[0019] A distal end of each finger is preferably positioned along the projection of an edge of one of the inlet or outlet ports of an adjacent distribution frame, depending on the stacking arrangement. Since the fingers, connected to the same common straight base, are parallel and of equal length, the aforementioned distal ends are aligned along a straight line segment corresponding to the projection of the edge of an inlet or outlet port. This design is distinguished by its simplicity, watertightness, and robustness, as the distal ends of the fingers support the distribution frames with the interposed metal sheets during the heat exchanger assembly.

[0020] In one embodiment, the heat exchanger according to the invention further comprises a metal mesh arranged in at least a portion of the fluid zone. Advantageously, the mesh is arranged to serve as a separation element between the hot and cold fluid zones. This mesh maintains a constant gap between these zones. Moreover, the metal mesh significantly contributes to the reinforcement of the metal sheets interposed between the distribution frames. It provides increased structural strength, protecting the sheets against deformation due to pressure variations and turbulence of the circulating fluids. The mesh openings are sized to provide minimal resistance to the flow while ensuring effective separation, thereby enhancing the overall stability of the heat exchanger.

[0021] This integration of the wire mesh into the heat exchanger design also facilitates assembly and maintenance, while ensuring the durability of the internal components. Preferably, the wire mesh is rectangular, as this shape is better suited to distribution frames with polygonal shapes, particularly those with a predominantly rectangular internal contour. This shape can be easily adjusted to match the right angles of the internal contour. The mesh can be easily cut and inserted precisely into the frame, thus maximizing space utilization in the fluid zone.

[0022] In another embodiment, each metal sheet has corrugations. The corrugations significantly increase the total surface area available for heat transfer compared to a flat surface. This allows for a greater heat transfer capacity within a given volume, thus improving the efficiency of the heat exchanger. Furthermore, the corrugations in the metal sheets disrupt the fluid flow, inducing turbulence. This embodiment also strengthens the metal sheets, making them less susceptible to deformation under pressure or temperature. This rigidity also contributes to greater durability and a longer service life for the heat exchanger. The use of corrugated metal sheets also makes the use of a wire mesh, as described above, optional.The role of the wire mesh can be transferred to the metal sheet by corrugations, which reduces the number of separate parts of the exchanger and simplifies its manufacture.

[0023] Preferably, the corrugations are inclined relative to the direction of fluid flow at the level of the metal sheet. This allows for more effective disturbance of the fluid flow by creating vortices and increased turbulence, which helps to improve heat transfer between fluids at the level of the metal sheets.

[0024] The corrugation angle is configured to minimize flow resistance, which can increase pressure drop. Instead, the angle is designed to maximize heat transfer between the two fluids. For example, it is typically between 30° and 60°, preferably between 30° and 40°. Ideally, the corrugations are sinusoidal, with a preferred amplitude of 1.0 to 2.0 mm, as these profiles are suitable for efficient heat exchange.

[0025] In one embodiment, the inner contour of each distribution frame features alternating convex and concave portions. The convex portions are sections of the contour that bulge inward toward the fluid zone, resembling bumps on the contour. Conversely, the concave portions curve outward from the fluid zone, forming depressions relative to the plane of the frame. Advantageously, by adopting an alternating shape for the inner contour, such as a corrugated or zigzag pattern, the fluid zone of each distribution frame can be increased. This expands the surface area available for heat transfer, thereby improving the thermal efficiency of the heat exchanger.

[0026] In one embodiment, each of the inlet and outlet ports in at least one distribution frame is positioned between a convex portion of the inner contour and an outer contour of the distribution frame. This allows for optimal use of the frame material, which is maximized opposite the convex surfaces. The inlet and outlet ports are thus offset in pairs. When the frames are stacked, the offset created at the ports is designed to ensure that they align correctly with those of neighboring frames. This precision is essential to guarantee that fluids flow efficiently throughout the entire structure without obstruction. Preferably, all or part of each distribution frame has an outer contour of the same rectangular shape, and each distribution frame fits within this contour, forming the visible outer sides of the heat exchanger.

[0027] The heat exchange according to this embodiment, and also more generally according to the invention, has the advantage of being modular in the sense that it can include a plurality of inlet and outlet ports per distribution frame without requiring major structural changes to the exchanger, unlike the exchangers described in WO 2022 / 074078 A1, which are equipped with one inlet and one outlet port. This effect is particularly evident in the preceding embodiment and in the embodiments described below (see, for example, the fluid flow arrows in figure 2 introduced below) because the alternation of convex and concave portions can be extended as needed, making the heat exchanger modular and more efficient.

[0028] In one embodiment, at least one distribution frame (and more preferably every other distribution frame depending on the stacking arrangement; namely, distribution frames having an internal contour delimiting a fluid zone of the same "type," i.e., hot or cold) has inlet and outlet ports in the form of open slots, each having an edge from which distribution protrusions extend outward from the fluid zone of said distribution frame. The distribution protrusions preferably have fingers (or, in other words, are straight-segmented) extending outward from the fluid zone.

[0029] Advantageously, this embodiment allows for uniform fluid distribution thanks to the pressure drop generated by the fingers. Indeed, the fingers modify the space available for fluid passage, causing a localized restriction of the flow. This restriction increases the local fluid velocity, which leads to a pressure drop. This pressure drop is useful for controlling the fluid velocity, ensuring that the fluid spends sufficient time in contact with the surfaces of the metal sheets in the fluid zones.

[0030] Preferably, the distribution projections are parallel and of similar length. Preferably, each distribution projection has a straight segment shape with one free end at the outer contour of one of the adjacent distribution frames in the stack. Equivalently, the free ends are therefore aligned along the projection of the outer contour of one of the adjacent distribution frames in the stack. The advantages described above for similar characteristics applied, in certain embodiments, to fingers connected to a common base also apply to these distribution projections, contributing in particular to a heat exchanger that is easier to manufacture and more leak-proof and robust.

[0031] The free ends of the distribution projections effectively support the outer contour of the adjacent distribution frame with the interposed metal sheets during heat exchanger assembly. The edge of each metal sheet can thus be locally compressed between two portions of the outer contours of distribution frames, or between such a portion and the free ends of the distribution projections. This contributes to a more robust heat exchanger construction and improved sealing without compromising the advantages of alternating convex and concave sections for the inner contour. Furthermore, since the distribution projections are similar, their contribution in terms of support and retention is evenly distributed, reducing the risk of deformation or failure in the heat exchanger wall.

[0032] In another embodiment, the heat exchanger according to the invention features cross-flow. Cross-flow, where the fluids move parallel to each other in opposite directions, advantageously allows for a larger thermal contact area between the fluids, potentially improving the heat transfer coefficient. Preferably, the fluids are at different pressures. Hot and cold fluids at different pressures can exhibit varying flow velocities, directly influencing turbulence and, consequently, the efficiency of heat transfer. A fluid at higher pressure can flow through the exchanger more quickly, thus increasing the heat transfer rate.

[0033] The heat exchanger may include a main inlet from the outside to the inside of the exchanger for the hot fluid and a main inlet from the outside to the inside of the exchanger for the cold fluid. One of these main inlets is preferably lateral and the other axial, depending on the direction of stacking. The configuration described in the six preceding paragraphs is particularly well-suited to such inlets, which allow for more efficient flow crossing and thus heat exchange.

[0034] The invention further proposes an energy production and / or cogeneration apparatus comprising a heat exchanger according to any one of the aforementioned embodiments. All the preferred embodiments and all the advantages of the heat exchanger according to the invention are transferable mutatis mutandis to the present device. More specifically, the device comprising: a combustion chamber; a turbine arranged to be supplied with combustion gases by the combustion chamber; a compressor mechanically coupled to the turbine; a motor-generator mechanically coupled to the turbine and the compressor; the heat exchanger according to the invention; in which the compressor is fluidly coupled to the combustion chamber via the heat exchanger, the latter being arranged to preheating compressed combustion air from the compressor before its injection into the combustion chamber.

[0035] Preferably, the combustion chamber is of the flameless type. Preferably, the combustion chamber comprises essentially a cylindrical chamber. The preheated combustion air exiting the heat exchanger is preferably introduced at one end of the combustion chamber. International publication WO 2016 / 124472 A1 gives an example of such a combustion chamber and its coupling with the heat exchanger.

[0036] In general, a person skilled in the art will understand that all embodiments relating to the exchanger apply to the energy production and / or cogeneration apparatus by positioning the exchanger in the manner provided for by the invention.

[0037] The invention also proposes a method for manufacturing a heat exchanger according to the invention, in which the distribution frames and metal sheets are assembled by high-temperature brazing under vacuum. As is known to those skilled in the art, "high-temperature" brazing is carried out at a temperature of approximately 600 to 1100°C, preferably 900 to 1000°C in the context of the invention. It is performed by applying a brazing alloy that impregnates the surfaces of the distribution frames and the metal sheets, thus enabling their assembly by atomic diffusion.

[0038] Advantageously, brazing is perfectly suited to manufacturing the heat exchanger according to the invention because it allows for rapid and robust fabrication of the heat exchanger without requiring the edges of the distribution frames and metal sheets to be melted. This makes it possible to ensure a solid and leak-proof bond between the distribution frames and the metal sheets, while maintaining the structural integrity of the heat exchanger and minimizing the risk of heat-induced deformation. It should be noted that the distribution frames and metal sheets can also be joined by diffusion welding (or " diffusion bonding " under vacuum which, through high-temperature pressure, creates adhesion between the diffusion frames and the metal sheets by atomic diffusion. Laser welding can be used as an alternative, given its precision and ability to target small areas. Brief description of the figures

[0039] Other features and advantages of the present invention will become apparent from the detailed description that follows, for understanding of which reference should be made to the accompanying figures, among which: there figure 1 illustrates an exploded view of a heat exchanger, according to one embodiment of the invention, the figure 2 illustrates an exploded view of a stack of two distribution frames separated by a metal sheet, according to one embodiment of the invention, the figure 3 illustrates an exploded view of a stack of two distribution frames, each incorporating a metal mesh and separated by a metal sheet, according to one embodiment of the invention, the figure 4 illustrates an exploded view of a stack of two distribution frames separated by a metal sheet having corrugations, according to an embodiment of the invention.

[0040] The drawings in the figures are not to scale. Similar features are generally denoted by similar reference numerals in the figures. Within the scope of this document, identical or analogous features may bear the same reference numerals. Furthermore, the presence of reference numerals or letters in the drawings shall not be considered limiting, even when such numerals or letters are specified in the claims. Detailed description of certain embodiments of the invention

[0041] This section provides a detailed description of certain embodiments of the present invention. The invention is described with specific embodiments and references to figures, but the invention is not limited by them. In particular, the drawings and figures described below are schematic only and are not limiting.

[0042] There figure 1Figure 1 illustrates a view of a heat exchanger 1 according to an embodiment of the invention. The heat exchanger 1 comprises a stack of planar distribution frames 31, 31'. Each of these distribution frames 31, 31' is characterized by an internal contour that delimits a hollow fluid zone 80 dedicated to the passage of a hot or cold fluid. The hot and cold fluid zones 80 alternate along a thickness of the exchanger 1. By "along a thickness," it is understood that along a stacking axis is the dimension along which this thickness is measured, the axis being denoted and represented by X on the figure. figure 1 The stacking is also considered along the X-axis. The term "thickness" is considered along this axis within the framework of this document.

[0043] The distribution frames 31, 31' can be manufactured in one piece or assembled from several metal components. Each distribution frame 31, 31' has inlet ports 11 and outlet ports 11 for the passage of fluids. As illustrated in the figure 1 These orifices 11 are, for example, circular and are aligned so as to ensure a fluid and continuous circulation through the stack. Preferably, two adjacent distribution frames 31, 31' are of identical design but reversed by 180° to each other, or positioned so that one is the mirror image of the other.

[0044] Between each pair of adjacent distribution frames 31, 31', thin metal sheets 32 are arranged to create thermal contact between the hot and cold fluid zones 80. These sheets are very thin, for example, on the order of 1 to 2 mm thick. They preferably have openings aligned with those 11 of the distribution frames 31, 31' to allow uninterrupted fluid flow at the heat exchanger 1.

[0045] The distribution frames 31, 31' are each provided with projections 4 ensuring local support for the metal sheets 32. The projections 4 extend from the inner contour towards the fluid zone 80. As illustrated in figure 2These projections 4 comprise fingers connected to a common base 41. Preferably, the fingers are parallel and of equal length, resembling the shape of a comb. Advantageously, the fingers at the projections 4 provide local support to the metal sheets 32 following the assembly of the heat exchanger 1. This support helps maintain the integrity of the metal sheets 32 by preventing their deflection or excessive vibration.

[0046] The structural integrity and sealing of the heat exchanger 1 are preferably ensured by the addition of lower and upper cover plates 51, 52 shown in figure 1 The plates 51, 52 are preferably thicker, and assembled by welding onto the edges of the exchanger 1. These plates 51, 52 guarantee the rigidity and complete sealing of the exchanger 1.

[0047] The heat exchanger 1 also includes main inlets and / or outlets 61, 62, 71 for the hot and cold fluids arranged at the level of the cover plates 51, 52. These structural elements are known to a person skilled in the art.

[0048] The materials used to manufacture heat exchanger 1 are selected for their resistance to corrosion and high temperatures. For example, high-chromium and high-nickel steels or special nickel-based alloys are preferred, allowing heat exchanger 1 to operate efficiently up to maximum temperatures of around 800°C.

[0049] There figure 2This represents a view of a stack of two distribution frames 31, 31' separated by a metal sheet 32. Preferably, the two distribution frames 31, 31' are identical in design but rotated 180° relative to each other, or positioned so that one is the mirror image of the other. Each distribution frame 31, 31' of the heat exchanger 1 is delimited by an outer contour and an inner contour. These contours, referenced by 33 for the inner contour and by 34 for the outer contour, are shown on one of the distribution frames 31 of the figure 1 as an example.

[0050] The inner contour of each distribution frame 31, 31' delimits a zone 80 of hot or cold fluid. The inner contour comprises alternating convex portions 21 and concave portions 22. This shape is, for example, undulating and located at two opposite sides of each distribution frame 31, 31'.

[0051] The corrugation on one side of a distribution frame 31, 31' is preferably out of phase with that on the opposite side. This means that the peaks of the corrugation on one side are aligned with the troughs on the opposite side, and vice versa. This increases the contact area between the hot and cold fluids, thus improving heat transfer. Each distribution frame 31, 31' has, for example, two inlet ports 11 and two outlet ports 11 for the fluid. In the embodiment shown in this figure, the inlet and outlet ports 11 are arranged between the convex portions 21 and the outer contour of the distribution frame 31, 31'.

[0052] Preferably, each distribution frame 31, 31' is provided with finger-shaped projections 4 connected to a common base 41. Preferably, the fingers extend at the fluid zone from the common base 41 and at a normal angle to it. As illustrated in the figure 2 The common base 41 of the fingers at the level of a distribution frame 31, 31' is preferably arranged along an orthogonal projection of an edge of one of the inlet or outlet orifices 11 of the adjacent distribution frame 31', 31. Preferably, the common base 41 extends from the inner contour so as to form a bridge in the fluid zone 80.

[0053] Positioned between the two distribution frames 31, 31', a thin metal sheet 32 ​​has orifices 11 that align with those of the adjacent distribution frames 31, 31' to allow uninterrupted fluid flow. This metal sheet 32 ​​acts as a direct thermal interface between the two fluid zones 80, thus facilitating heat exchange. The hot and cold fluids preferably flow in opposite directions, as schematically illustrated by the arrows at the level of the figure 2 .

[0054] In one direction of flow, the cold fluid enters through the orifices 11 located in the distribution frame 31', then passes through the thin metal sheet 32 ​​that separates the two distribution frames 31 and 31' to enter the cold fluid zone 80 at the distribution frame 31. Simultaneously, in the opposite direction of flow, the hot fluid enters through the orifices 11 of the distribution frame 31, passes through the same metal sheet 32, and enters the fluid zone 80 of the distribution frame 31'. Once in the fluid zone, the fingers at the protrusions 4 act as guide channels at the inlet to direct the fluid flow towards the center of the fluid zones 80. The fingers, preferably comb-shaped, support the metal sheet 32 ​​and also ensure a uniform distribution of the fluid, thus avoiding unnecessary turbulence and optimizing heat transfer.

[0055] The fluids continue their path until they reach the opposite ends of their respective fluid zones 80, where they exit through the corresponding ports 11. Similarly, the fingers direct the fluids at the outlet of the fluid zone 80. This counter-current configuration ensures a constant temperature gradient along the entire length of the heat exchanger, promoting more efficient and uniform heat transfer. The fingers at the inlet and outlet of the fluid zone 80 can, for example, have a thickness approximately half that of the corresponding distribution frame 31, 31'.

[0056] There figure 3This illustrates an exploded view of a stack of two distribution frames 31, 31', each incorporating a metal mesh 9 and separated by a metal sheet 32. The distribution frames 31, 31' preferably have polygonal shapes. Each distribution frame 31, 31' includes, for example, rectangular inlet and outlet ports 11 arranged to promote smooth distribution at the heat exchanger 1.

[0057] As illustrated on the figure 3Each distribution frame 31, 31' comprises, for example, three inlet ports 11 and three outlet ports 11, symmetrically distributed on two opposite sides. The inner contour of each distribution frame 31, 31' preferably has zigzag shapes, exhibiting alternating convex portions 21 and concave portions 22. Two or more such inlet and outlet ports make the heat exchanger more efficient, although a different number of ports is not limiting the scope of the invention. These shapes are typically staggered on two opposite sides of each distribution frame 31, 31'. At the first distribution frame 31, for example, the ports may be positioned between convex portions 21 of the inner contour and the outer contour of the distribution frame 31.

[0058] Preferably, each of the distribution frames 31, 31' has projections 4 comprising fingers connected to a common base 41. The common base 41 extends into the fluid zone 80, following a straight path so as to form a bridge in this zone 80. Preferably, these fingers are located in the immediate vicinity of the inlets and outlets of the fluid zone 80. These fingers are preferably oriented normally towards the interior of the fluid zone 80. They are, for example, spaced 1 to 2 mm apart, preferably about 1 mm, for good stacking support. As illustrated in the figure 3 , the fingers connected to the same common base 41 have distal ends aligned according to an orthogonal projection of an edge of one of the orifices 11 of entry or exit of the distribution frame 31', 31 adjacent.

[0059] Regarding the second distribution frame 31', positioned opposite the first distribution frame 31, it is preferably its mirror image, except for the configuration of the inlet and outlet ports 11. These are preferably designed as open slots, each having an edge from which distribution projections 6 extend outwards from the fluid zone 80 of the distribution frame 31'. These projections 6 preferably have fingers connected to an edge of one of the slots. Even more preferably, the distribution projections 6 have a structure similar to the support projections 4 located at the level of the fluid zone 80 but are oriented in the opposite direction.The fingers at the distribution protrusions 6 create a pressure drop improving the uniform distribution of the fluid but also contribute to the sealing of the exchanger 1 by supporting the external contour of an adjacent distribution frame 31 depending on the stacking when the fingers have free ends extending at the level of the latter, as illustrated in . figure 3 .

[0060] Preferably, a wire mesh 9 is inserted into at least a portion of the fluid zone 80 of each distribution frame 31, 31'. The wire mesh 9 is formed by vertically and horizontally crossed wires to create a mesh. The wires preferably have a diameter of approximately half the thickness of the corresponding fluid zone 80. The wire mesh 9 can be welded to the distribution frames 31, 31' and to the metal sheet 32 ​​using the techniques described above. The wire mesh 9 can occupy the entire void in the fluid zone 80 perpendicular to the stack. As illustrated in the figure 3A simple metal sheet 32 ​​is placed between the two distribution frames, acting as a thermal conductor, allowing heat transfer between the hot and cold fluids of the heat exchanger 1. This metal sheet 32 ​​is thin to maximize thermal efficiency. The metal sheet 32 ​​has openings that correspond to those of the two distribution frames 31, 31'.

[0061] There figure 4 illustrates an exploded view of a stack of two distribution frames 31, 31' separated by a corrugated metal sheet 32. According to this figure, the two distribution frames 31, 31' are designed identically to that of the figure 3 . Each distribution frame 31, 31' has an external contour and an internal contour with zigzag shapes, optimizing space for fluid flow.

[0062] As illustrated on the figure 4A different type of metal sheet 32 ​​can be placed between the two distribution frames 31, 31'. This metal sheet 32 ​​preferably has corrugations 321. These corrugations are preferably inclined with respect to a direction of fluid flow along the metal sheet 32. Preferably, the corrugations 321 have an angle of inclination between 30° and 40° with respect to the extension plane of the distribution frames 31, 31'. The corrugations 321 can, for example, have a sinusoidal or V-shaped form. Advantageously, the corrugations add rigidity to the metal sheet 32, allowing it to better withstand internal pressures and impacts without significant bending or deformation. In addition, the effective surface area of ​​the metal sheet 32 ​​increases without requiring more material. This allows for better heat transfer by exposing more surface area to the fluid.

[0063] The manufacture of corrugated metal sheets 32 can be carried out by several techniques, including stamping which uses dies and punches to form corrugations 321 in the metal sheet 32. The metal sheet 32 ​​is placed between a female die and a male punch which presses and forms the metal into the desired shape.

[0064] In summary, the invention relates to a heat exchanger 1 for preheating the combustion air of a micro-turbine in a cogeneration system. The structure of this heat exchanger 1 comprises an assembly of flat distribution frames 31, 31' and spacer metal sheets 32. Each distribution frame 31, 31' is defined by a contour enclosing a fluid zone 80 and is equipped with orifices 11 for the passage of the fluid. The metal sheets 32 are supported by support projections 4 at the distribution frames 31, 31', simplifying the fabrication of the heat exchanger 1.

[0065] The present invention has been described above in relation to specific embodiments, which are purely illustrative and should not be considered limiting. Unless otherwise stated, the numerical values ​​provided as examples are given with a margin of error of 10%. It will be readily apparent to those skilled in the art that the invention is not limited to the examples illustrated or described above, and that its scope is more broadly defined by the claims introduced below.

Claims

1. Heat exchanger (1) for an energy production and / or cogeneration unit, and comprising: - a stack of planar distribution frames (31, 31'), each having an internal contour delimiting a zone (80) of hot or cold fluid, said zone (80) of fluid communicating with inlet ports (11) and outlet ports (11) of the fluid, provided in each of the adjacent distribution frames (31, 31'), the hot and cold zones (80) of fluid alternating along a thickness of the exchanger (1); - metal sheets (32) arranged alternately with the distribution frames (31, 31') according to the stacking to create thermal contact between said zones (80) of fluid; characterized in that Each of the distribution frames (31, 31') is provided with support projections (4) extending from said internal contour to said fluid zone (80).

2. Heat exchanger (1) according to claim 1, wherein the projections (4) comprise a plurality of fingers connected to a common base (41) extending into said fluid zone (80).

3. Heat exchanger (1) according to claim 2, wherein the common base (41) and / or a portion of each finger is arranged according to a projection of an edge of one of the inlet or outlet ports (11) of one of the distribution frames (31, 31') adjacent according to the stacking.

4. Heat exchanger (1) according to claim 2 or 3, in which the fingers (4) extend at the level of the fluid zone (80) from the common base (41) and in a normal manner with respect to it.

5. Heat exchanger (1) according to any one of claims 1 to 4, wherein the distribution frames (31, 31') have essentially polygonal shapes with rectangular inlet and outlet ports (11).

6. Heat exchanger (1) according to claim 5 when it depends on claim 2, wherein the common base (41) is straight and wherein the fingers are parallel and of the same length.

7. Heat exchanger (1) according to claim 6, wherein a distal end of each finger is arranged along a projection of an edge of one of the inlet or outlet ports (11) of one of the distribution frames (31, 31') adjacent according to the stacking.

8. Heat exchanger (1) according to any one of claims 1 to 7, further comprising a metal mesh (9) arranged in at least a part of the fluid zone (80).

9. Heat exchanger (1) according to any one of claims 1 to 7, wherein each metal sheet (32) has corrugations (321) inclined with respect to a direction of fluid flow at the level of said metal sheet (32).

10. Heat exchanger (1) according to any one of claims 1 to 9, wherein the inner contour of each of the distribution frames (31, 31') comprises an alternation of convex (21) and concave (22) portions, each of the inlet and outlet orifices (11) being disposed between a convex portion (21) of the inner contour and an outer contour of said distribution frame (31, 31').

11. Heat exchanger (1) according to any one of claims 1 to 11, wherein at least one distribution frame (31') has inlet and outlet ports (11) in the form of open slots, each having an edge from which distribution projections (6) extend externally relative to the fluid zone (80) of said distribution frame (31').

12. Heat exchanger (1) according to claim 11 when it depends on claim 10, wherein the distribution projections (6) each have a straight segment shape having a free end at the outer contour of one of the distribution frames (31) adjacent according to the stacking.

13. Heat exchanger (1) according to any one of claims 1 to 12, which is cross-flow.

14. Power generation and / or cogeneration apparatus comprising: - a combustion chamber; - a turbine arranged to be supplied with combustion gas by the combustion chamber; - a compressor mechanically coupled to the turbine; - a motor-generator mechanically coupled to the turbine and the compressor; - the heat exchanger (1) according to any one of claims 1 to 13; wherein the compressor is fluidly coupled to the combustion chamber via the heat exchanger (1), the latter being arranged to preheat combustion air compressed by the compressor before its injection into the combustion chamber.

15. Method of manufacturing a heat exchanger (1) according to any one of claims 1 to 13, wherein the distribution frames (31, 31') and the metal sheets (32) are assembled by high-temperature vacuum brazing.

Images