HEAT EXCHANGER

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Belgian Patent Application No. BE 2024/5296 filed May 22, 2024, the disclosure of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a “heat exchanger” (also referred to herein as an “exchanger”) for preheating combustion air from a compressor of a micro-turbine of an energy production and/or cogeneration apparatus.

BACKGROUND

A heat exchanger, particularly in cogeneration systems equipped with gas micro-turbines, plays a decisive role in improving overall efficiency. It performs the essential function of preheating the combustion air by recovering the thermal energy still present in the exhaust gases from the turbine. For example, such a heat exchanger can be made by means of a structure conventionally composed of an arrangement of exchange plates arranged between distribution frames and reinforced by metallic lattices inserted into the frames. This configuration facilitates efficient alternating exchange between hot and cold fluids, optimizing heat transfer. However, the manufacture of such a heat exchanger can encounter a number of difficulties, particularly when it comes to making metallic lattices, which can take on complex shapes.

The international publication WO 2016/124472 A1 presents such a heat exchanger design, integrated in an energy cogeneration system equipped with a gas micro-turbine. The publication WO 2022/074078 A1 discloses a heat exchanger in which central leakage zones are formed for a leakage fluid in 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 evacuated through lateral orifices in these frames or through specific end inlets and outlets provided in the exchanger.

SUMMARY

One object, among others, of this disclosure is to provide a heat exchanger that is more robust and simpler to manufacture than the prior art.

To this end, a heat exchanger is proposed for an energy production and/or cogeneration apparatus. In an embodiment, the apparatus comprises:

• • 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 orifices and outlet orifices formed in each of the adjacent frames (according to the stack), the hot and cold fluid zones alternating along a thickness of the exchanger;
  • metal sheets arranged alternately with the distribution frames in the stack to create thermal contact between said fluid zones;
  • each of the distribution frames is provided with support projections extending from the internal contour towards the fluid zone.

The exchanger according to embodiments of the disclosure is robust and simpler to manufacture. This is because, for example, the support projections, which extend from the internal contour of the frames towards the zones where the fluids flow, act as an internal structural support for the metal sheets. By projecting into the zones where the fluid circulates, these protrusions help to maintain the integrity of the sheets against mechanical stresses, particularly the pressure differential between the hot and cold zones.

In addition, integrating the projections directly into the distribution frames can help eliminate the need for additional components such as metallic lattices or other forms of external reinforcement. They can therefore help to simplify the manufacturing process by reducing the number of separate parts to be manufactured and assembled. By reducing the complexity of the components required to assemble the exchanger, the production costs are reduced. The manufacturing process becomes more straightforward, allowing for standardization, easier logistics, and potential economies of scale during mass production.

As anyone skilled in the art will appreciate, the distribution frames guiding the flux of hot and cold fluids are arranged in such a way as to enable them to be stacked in an orderly fashion. The metal sheets are arranged alternately with these distribution frames so that each metal sheet is placed between two successive frames. In other words, the exchanger stack is designed with an alternating arrangement where each distribution frame (delimiting a hot or cold fluid zone) is followed by a metal sheet, then by another distribution frame (delimiting a cold or hot fluid zone), and so on along the thickness of the exchanger. The arrangement of the metal sheets follows this sequence, so as to achieve thermal contact between the alternating zones of hot and cold fluids.

The term “fluid zone” refers to the region specifically delimited by the internal contour of each of the distribution frames where the hot or cold fluids circulate for the heat transfer. Each fluid zone communicates with specific openings that are used to let fluids in and out. The “inlet orifices” allow the fluid to enter the fluid zone for heat transfer, and the “outlet orifices” allow the fluid to leave the zone after exchanging heat. These orifices are integrated or incorporated into the distribution frames, which are positioned next to each other (i.e. adjacent to each other) in the structure of the exchanger. Each frame has its own orifices for the passage of the fluids, allowing continuous circulation with those of neighboring frames through the exchanger.

It should be noted that for purposes of this disclosure, the use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Similarly, the use in this document of the indefinite article “a”, “an”, or the definite article “the” to introduce an element does not exclude the presence of a plurality of these elements. The present specification may reference quantities and numbers. Unless specifically stated, such quantities and numbers are not to be considered restrictive. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Generally, throughout the specification, terms of art may be used. These terms are to take on their ordinary meaning in the art from which they come, unless specifically defined herein or the context of their use would clearly suggest otherwise.

In an embodiment of the present disclosure, the projections comprise a plurality of fingers connected to a common base. More specifically, the protrusions are grouped in sets, each formed by a plurality of fingers connected to a common base. Advantageously, the fingers add extra strength to the structure of the heat exchanger. This configuration of projections also allows to increase the support surface for metal sheets. There is sufficient spacing between the fingers to allow hot and cold fluids to circulate. This improves the robustness and efficiency of the exchanger. The fingers can have a rectangular cross-section (in the direction in which they extend) because they are projections from a flat frame. For the purposes of this document, the term “fingers” may be replaced by “elongated bodies” or “elongated elements”.

In an embodiment, the common base can extend from the internal contour towards the fluid zone so as to form a bridge. This means that the common base connecting the fingers, extends from the internal contour through the fluid zone to reach the opposite side, thus forming a bridge across this zone. The common base therefore extends into the fluid zone.

In an embodiment, the fingers are parallel and of equal length. Advantageously, this allows the mechanical forces to be distributed evenly across the metal sheets, reducing the risk of deformation or breakage. This also facilitates the design and manufacture of the distribution frames. The fingers can be identical.

In an embodiment, the common base is arranged according to a projection of an edge of one of the inlet or outlet orifices of one of the adjacent distribution frames in the stack. As the skilled person will understand, the common base can be more precisely an orthogonal projection along the stack (or equivalently along the thickness of the exchanger), at the level of the frame in which the projections are. The common base then provides support for the adjacent distribution frame when assembling the exchanger, in particular by brazing or diffusion welding as explained below, contributing to better sealing and strength of the exchanger.

Alternatively or additionally, part of each finger is arranged in such a projection. In other words, each finger can intersect such a projection. The fingers (and in both cases, the projections) support the distribution frames when assembling the above-mentioned exchanger, which improves the exchanger's tightness and robustness.

In an embodiment, the fingers extend at the fluid zone from the common base and normally with respect to it. Advantageously, this embodiment ensures that hot and cold fluid flux are directed more efficiently into and out of the fluid zone. This means that the hot or cold fluid is guided into the fluid zone, without unnecessary dispersion that could reduce heat transfer efficiency. This finger configuration also helps to stabilize the flux of fluids in and out, reducing the turbulence that can occur as fluids move from one fluid zone to another. The disclosure thus provides a more orderly and less resistive fluid path, which can contribute to the overall efficiency of heat exchange.

In an embodiment, the distribution frames are essentially polygonal in shape. Polygonal shapes are angular shapes made up of a finite sequence of consecutive line segments. Advantageously, this shape is easy to manufacture. For example, the distribution frames may incorporate rectangular inlet and/or outlet orifices (the term “rectangular” also covering the case of “square”) and have internal contours that are rectangular or comprise zigzag shapes. These shapes are easier to cut and integrate into metal structures than rounded or irregular shapes. This can reduce production costs and simplify the assembly of the components of the exchanger.

In this case, the common base (possibly of each set of projections as aforesaid) is rectilinear and has fingers connected thereto which are parallel and of the same length. This is a particularly simple and robust design, with all the frame elements being straight. The mechanical forces are distributed evenly across the metal sheets thanks to the configuration of the fingers.

A distal end of each finger can be arranged according to a projection of an edge of one of the inlet or outlet orifices of one of the adjacent distribution frames in the stack. As the fingers connected to the same common rectilinear base are parallel and of the same length, the aforementioned distal ends are aligned along a straight segment corresponding to the projection of the edge of an inlet or outlet orifice. The design stands out for its simplicity, watertightness and robustness, because the (distal ends of the) fingers support the distribution frames with the metal sheets interposed during assembly of the exchanger.

In an embodiment, the exchanger also comprises a metallic lattice arranged in at least part of the fluid zone. Advantageously, the lattice is arranged to act as a separating element between the hot and cold fluid zones. This lattice allows a constant gap to be maintained between these zones. The metallic lattice also makes a significant contribution to reinforcing the metal sheets between the distribution frames. It offers increased structural strength, protecting sheets from deformation due to pressure variations and turbulence from circulating fluids. The mesh of the lattice is dimensioned to provide minimum resistance to flow while ensuring effective separation, which enhances the overall stability of the exchanger.

This integration of the metallic lattice into the exchanger design also facilitates installation and maintenance, while guaranteeing the durability of the internal components. The metallic lattice can adopt a rectangular shape, which may be better suited to distribution frames with polygonal shapes, in particular with an essentially rectangular internal contour. This shape can be easily adjusted to match the right angles of the internal contour. The lattice can be easily cut to fit exactly into the frame, maximizing the use of space in the fluid zone.

In another embodiment, each metal sheet has corrugations. The corrugations considerably increase the total surface area available for heat transfer compared with a flat surface. This allows a greater heat transfer capacity in a given volume, which improves the efficiency of the exchanger. In addition, the corrugations in the metal sheets disrupt the flow of fluids, inducing the turbulence. In addition, this method reinforces the metal sheets, making them less likely to deform under the effect of pressure or temperature. This rigidity also contributes to greater durability and a longer life for the exchanger. The use of a metal sheet with corrugations also makes the use of a metallic lattice as described above optional. The role of the metallic lattice can be transferred to the metal sheet by the corrugations, reducing the number of separate parts in the exchanger and simplifying its manufacture.

In an embodiment, the corrugations can be inclined with respect to a direction of fluid flow at said metal sheet. This disrupts the fluid flux more effectively by creating vortices and increased turbulence, helping to improve heat transfer between the fluids at the metal sheets.

In an embodiment, the angle of inclination of the corrugations is configured so as not to induce great resistance to flow, which can increase the pressure drop. The angle of inclination is configured to optimally maximize the rate of heat transfer between the two fluids. For example, it is between 30° and 60°, more precisely between 30° and 40°. The corrugations can be sinusoidal, e.g. with a more specific amplitude of 1.0 to 2.0 mm, these profiles being suitable for good heat exchange.

In an embodiment, the internal contour of each of the distribution frames comprises alternating convex and concave portions. The convex portions refer to sections of the contour that bulge towards the inside of the fluid zone. They therefore look like bumps on the contour. In addition, the concave portions are curved externally with respect to the fluid zone, forming hollows with respect to the plane of the frame. Advantageously, by adopting an alternating shape for the internal contour, such as a wavy or zigzag shape, the fluid zone of each distribution frame can be increased. This extends the surface area available for heat transfer, improving the heat exchanger's thermal efficiency.

In an embodiment, each of the inlet and outlet orifices in at least one distribution frame is disposed between a convex portion of the internal contour and an external contour of the distribution frame. This allows optimum use to be made of the frame material, which becomes maximum in front of the convex portions. The inlet and outlet orifices are thus staggered in pairs. When the frames are stacked, the offset created at the orifices is designed to ensure that they align correctly with those of neighboring frames. This precision is essential to ensure that fluids flow efficiently throughout the structure without obstruction. According to embodiments, all or part of each distribution frame has an external contour of the same rectangular shape and each distribution frame fits within this contour, forming the visible outer sides of the heat exchanger.

The heat exchanger according to this embodiment, but also generally according to the disclosure, including one or more aspects thereof, has the advantage of being modular in the sense that it can comprise a plurality of inlet and outlet orifices per distribution frame without the need for major structural changes to the exchanger, unlike the exchangers described in WO 2022/074078 A1 which are provided with an inlet and outlet orifice. This effect is particularly apparent in the previous embodiment and in the embodiments described below (see, for example, the fluid flow arrows in FIG. 2, introduced below) because the alternation of convex and concave portions can be extended as required, making the heat exchanger modular and more efficient.

In an embodiment, at least one distribution frame (and possibly one distribution frame in every two depending on the stacking; i.e. distribution frames having an internal contour delimiting a fluid zone of the same “type”, i.e. hot or cold) comprises inlet and outlet orifices in the form of open slots, each having an edge from which distribution projections extend externally with respect to the fluid zone of said distribution frame. The distribution projections can comprise fingers (or, in other words, can have the shape of a straight segment) extending externally with respect to the fluid zone.

Advantageously, this embodiment, for example, allows uniform distribution of the fluids thanks to the pressure drop generated by the fingers. In fact, the fingers modify the space available for the fluid to pass through, causing a localized restriction of the flux. This restriction increases the local velocity of the fluid, resulting in a drop in pressure. This pressure drop is useful for controlling velocity of the fluid, ensuring that the fluid spends sufficient time in contact with the surfaces of the metal sheets at the fluid zones.

In an embodiment, the distribution projections can be parallel and of similar length. Each can have the shape of a straight segment with a free end at the external contour of one of the adjacent distribution frames in the stack. Equivalently, the free ends are therefore aligned with the projection of the external contour of one of the adjacent distribution frames in the stack. The above-mentioned advantages for similar characteristics applied, in certain embodiments, to fingers connected to a common base also apply to these distribution projections, contributing in particular to an exchanger that is easy to manufacture and more watertight and robust.

For example, the (free ends of the) distribution projections effectively support the external contour of the adjacent distribution frame with the interposed metal sheets during assembly of the exchanger. Each metal sheet, for example, the edge of or edges of, can thus be locally crushed between two portions of the external contours of distribution frames or between such a portion and the free ends of such distribution projections, which contributes to more robust manufacture of the exchanger and to its sealing without losing the advantages of alternating convex and concave portions for the internal contour. As the distribution projections are also similar, their contribution in terms of support and holding is harmoniously distributed, reducing the risk of deformation or breakage in the wall of the exchanger.

In an embodiment, the flow of the fluids in the exchanger move parallel to each other in opposite directions, advantageously allowing for a larger thermal contact surface between the fluids, potentially improving the heat transfer coefficient. The fluids can have different pressures. The hot and cold fluids at different pressures can have varying flow velocities, directly influencing turbulence and therefore heat transfer efficiency. A fluid under higher pressure can pass through the exchanger more quickly, increasing the rate of heat transfer.

In an embodiment, the exchanger can comprise 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 for instance lateral and the other is for instance axial in the stacking direction. The configuration described in the previous six paragraphs is particularly well-suited to such inlets, which enable flows to be crossed more effectively and thus heat to be exchanged.

The disclosure further provides an energy production and/or cogeneration apparatus comprising an exchanger according to any of the aforementioned embodiments. All the embodiments as well as all the advantages of the exchanger according to the disclosure are transposed mutatis mutandis to the present apparatus. In an embodiment, the apparatus comprises:

• • a combustion chamber,
  • a turbine arranged to be supplied with combustion gases from the combustion chamber;
  • a compressor mechanically coupled to the turbine;
  • a motor-generator mechanically coupled to the turbine and compressor;
  • the heat exchanger according to any embodiment of the disclosure;
  • wherein the compressor is fluidically coupled to the combustion chamber via the heat exchanger, the latter being arranged to preheat combustion air compressed by the compressor before it is injected into the combustion chamber.

In an embodiment, combustion chamber can be of the “flameless” type. According to an embodiment, the combustion chamber mainly comprises a cylindrical chamber. The preheated combustion air leaving the heat exchanger is typically introduced at one end of the combustion chamber. The publication WO 2016/124472 A1 gives an example of such combustion chamber and its coupling with the heat exchanger.

Generally speaking, the person skilled in the art will understand that all the embodiments relating to the exchanger apply to the energy production and/or cogeneration apparatus by positioning the exchanger in the manner provided by the disclosure.

The disclosure also proposes a method for manufacturing a heat exchanger according to the disclosure, wherein the distribution frames and metal sheets are assembled by high-temperature brazing under vacuum. As is known to a person skilled in the art, “high-temperature” brazing is carried out at a temperature of around 600 to 1100° C., e.g. 900° to 1000° C. in the context of the disclosure. It is produced by adding a brazing alloy that impregnates the surfaces of the distribution frames and the metal sheets, enabling them to be assembled by atomic diffusion.

Advantageously, brazing is perfectly suited to the manufacture of the exchanger according to the disclosure because it allows rapid and robust manufacture of the heat exchanger without requiring fusion of the edges of the distribution frames and metal sheets. This ensures a strong, watertight bond between the distribution frames and the metal sheets, while maintaining the structural integrity of the heat exchanger and minimizing the risk of heat distortion. It should be noted that the distribution frames and metal sheets can also be assembled by vacuum diffusion bonding, which allows adhesion between the diffusion frames and metal sheets to be created by atomic diffusion under high temperature pressure. Alternatively, laser welding can be used, given its precision and ability to target small zone.

The disclosed subject matter is further introduced in the claims. As it will be understood by a skilled person from the present disclosure, any one of the embodiments presented in these claims can be considered alone or in combination. In particular, the dependency of the claims can be considered in a broader manner so that any one of the possible combinations of the claims—as far as they are technically possible and understood by the person skilled in the art, in particular in view of the present disclosure—are part of the present application.

DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of this disclosure will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 shows an exploded view of an exchanger, according to an embodiment of the disclosure;

FIG. 2 shows an exploded view of a stack of two distribution frames separated by a metal sheet, according to an embodiment of the disclosure;

FIG. 3 illustrates an exploded view of a stack of two distribution frames, each incorporating a metallic lattice and separated by a metal sheet, according to an embodiment of the disclosure; and

FIG. 4 shows an exploded view of a stack of two distribution frames separated by a metal sheet with corrugations, according to an embodiment of the disclosure.

The drawings in the FIGURES are not to scale. Similar elements are generally denoted by similar references in the FIGURES. In the scope of this document, the same or similar elements may have the same references. Furthermore, the presence of reference numbers or letters in the drawings may not be considered as limiting, even when these numbers or letters are indicated in the claims

DETAILED DESCRIPTION

This section provides a detailed description of certain embodiments of the present disclosure. The latter is described with particular embodiments and references to FIGURES but the disclosure is not limited by them. In particular, the drawings and FIGURES described below are only schematic and are not limiting.

In the following description, details are set forth to provide a thorough understanding of representative embodiments of the present disclosure. It will be apparent to one skilled in the art, however, that the embodiments disclosed herein may be practiced without embodying all of the specific details. In some instances, well-known process steps or structural elements have not been described in detail in order not to unnecessarily obscure various aspects of the present disclosure. Further, it will be appreciated that embodiments of the disclosure may employ any combination of features described herein.

FIG. 1 shows a view of a heat exchanger 1 according to an embodiment of the disclosure. The heat exchanger 1 comprises a stack of flat distribution frames 31, 31′. Each of these distribution frames 31, 31′ is characterized by an internal contour which delimits a hollow fluid zone 80 dedicated to the passage of a fluid, hot or cold. The hot and cold fluid zones 80 alternate along the length of the heat exchanger 1. By “along a thickness” is meant along a stacking axis along which this thickness is measured, the axis being noted and represented by X in FIG. 1. The stack is also considered along the stacking axis X. The term “thickness” is considered along this axis for the purposes of this document.

The distribution frames 31, 31′ can be made in one piece or assembled from several metal elements. The distribution frames 31, 31′ are each provided with inlet orifices 11 and outlet orifices 11 for the passage of fluids. As shown in FIG. 1, these orifices 11 are circular, for example, and are aligned to ensure continuous fluid flow through the stack. Two adjacent distribution frames 31, 31′ can be identical in design but turned 180° in relation to each other, or positioned so that one is the image of the other by mirror symmetry.

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 around 1 to 2 mm thick. They have orifices aligned with those 11 in the distribution frames 31, 31′ to allow fluids to pass through the exchanger 1 without interruption.

The distribution frames 31, 31′ are each fitted with projections 4 providing local support for the metal sheets 32. The projections 4 extend from the internal contour towards the fluid zone 80. As illustrated in FIG. 2, these projections 4 comprise fingers connected to a common base 41. The fingers are parallel and of the same length, reminiscent of the shape of a comb. The fingers at the projections 4 provide local support for the metal sheets 32, following assembly of the exchanger 1. This support helps to maintain the integrity of the metal sheets 32 by preventing them from sagging or vibrating excessively.

The structural integrity and tightness of the heat exchanger 1 can be ensured by the addition of lower and upper cover plates 51, 52 as shown in FIG. 1. The plates 51, 52 can be thicker and welded to the edges of the exchanger 1. These plates 51, 52 guarantee rigidity and complete sealing of the exchanger 1.

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

The materials used to manufacture heat exchanger 1 are selected for their resistance to corrosion and high temperatures. For example, steels with a high chromium and nickel content or special nickel-based alloys can be used, enabling the heat exchanger 1 to operate efficiently up to maximum temperatures of around 800° C.

FIG. 2 shows a stack of two distribution frames 31, 31′ separated by a metal sheet 32. The two distribution frames 31, 31′ are identical in design but turned 180° in relation to each other, or positioned so that one is the image of the other in a mirror. Each distribution frame 31, 31′ of the heat exchanger 1 is delimited by an external and an internal contours. These contours, referenced 33 for the internal contour and 34 for the external contour, are shown on one of the distribution frames 31 in FIG. 1 by way of example.

The internal contour of each distribution frame 31, 31′ delimits a hot or cold fluid zone 80. The internal contour comprises alternating convex 21 and concave 22 portions. This shape is wavy, for example, and is located on two opposite sides of each distribution frame 31, 31′.

The corrugation on one side of a distribution frame 31, 31′ can be out of phase with that on the opposite side. This means that the wave crests on one side are aligned with the troughs on the opposite side, and vice versa. This increases the contact surface between the hot and cold fluids, improving heat transfer. Each distribution frame 31, 31′ has, for example, two fluid inlet orifices 11 and two fluid outlet orifices 11. In the embodiment shown in this FIGURE, the inlet and outlet orifices 11 are arranged between the convex portions 21 and the external contour of the distribution frame 31, 31′.

Each distribution frame 31, 31′ is provided with finger-like projections 4 connected to a common base 41. In the illustrated embodiments, the fingers extend into the fluid zone from and normal to the common base 41. As illustrated in FIG. 2, the common base 41 of the fingers at a dispensing frame 31, 31′ is arranged along an orthogonal projection of an edge of one of the inlet or outlet orifices 11 of the adjacent dispensing frame 31′, 31. The common base 41 extends here from the internal contour so as to form a bridge in the fluid zone 80.

Placed between the two distribution frames 31, 31′, a thin metal sheet 32 comprises orifices 11 which align with those of the adjacent distribution frames 31, 31′ to allow uninterrupted passage of the fluids. This metal sheet 32 acts as a direct thermal interface between the two fluid zones 80, facilitating heat exchange. The hot and cold fluids can flow in opposite directions, as shown by the arrows in FIG. 2.

According to a first 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 separating the two distribution frames 31, 31′ to enter the cold fluid zone 80 in the distribution frame 31. At the same time, in the opposite direction of flow, the hot fluid enters via 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, which can be comb-shaped, support the metal sheet 32 and also ensure uniform distribution of the fluid, avoiding unnecessary turbulence and optimizing heat transfer.

The fluids continue their journey until they reach the opposite ends of the respective fluid zones 80, where they exit via the corresponding orifices 11. Similarly, the fingers allow the fluids to be directed out of the fluid zone 80. This counter-current configuration ensures a constant temperature gradient along the entire length of the exchanger, promoting more efficient and uniform heat transfer. The fingers at the entrance and exit of the fluid zone 80 may, for example, have a thickness of approximately half the thickness of the corresponding distribution frame 31, 31′.

FIG. 3 shows an exploded view of a stack of two distribution frames 31, 31′, each incorporating a metallic lattice 9 and separated by a metal sheet 32. The distribution frames 31, 31′ are polygonal in shape. Each distribution frame 31, 31′ comprises, for example, rectangular inlet and outlet orifices 11 arranged to promote fluid distribution in the heat exchanger 1.

As shown in FIG. 3, each distribution frame 31, 31′ comprises, for example, three inlet orifices 11 and three outlet orifices 11, symmetrically distributed on two opposite sides. The internal contour of each distribution frame 31, 31′ can comprise zigzag shapes, with alternating convex 21 and concave 22 portions. Two or more such inlet and outlet orifices make the heat exchanger more efficient, although other numbers of orifices are not limiting to the scope of the disclosure. These shapes are typically present out of phase on two opposite sides of each distribution frame 31, 31′. As shown on FIG. 3, on the first distribution frame 31, these orifices are positioned between convex portions 21 of the internal contour and the external contour of the distribution frame 31.

Each of the distribution frames 31, 31′ comprises support projections 4 comprising fingers connected to a common base 41. The common base 41 extends into the fluid zone 80, following a straight trajectory so as to form a bridge in this zone 80. As shown, these fingers are located in the immediate vicinity of the inlets and outlets of the fluid zone 80. These fingers are oriented normally towards the inside of the fluid zone 80. For example, they are spaced 1 to 2 mm apart, e.g. around 1 mm apart, for good stacking support. As illustrated in FIG. 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 inlet or outlet orifices 11 of the adjacent distribution frame 31′, 31.

In the illustrated embodiment of FIG. 3, the second distribution frame 31′, positioned opposite the first distribution frame 31, is its mirror image, with the exception of the configuration of the inlet and outlet orifices 11. These are designed as open slots, each having an edge from which dispensing projections 6 extend outwardly relative to the fluid zone 80 of the dispensing frame 31′. These projections 6 comprise fingers connected to an edge of one of the slots. These can adopt a similar structure to the support projections 4 located at the fluid zone 80 but are oriented in the opposite direction.

The fingers at the level of the distribution projections 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 according to the stack when the fingers have free ends extending at the level of the latter, as illustrated in FIG. 3.

A metallic lattice 9 can be inserted into at least part of the fluid zone 80 of each distribution frame 31, 31′. In a known way, the metallic lattice 9 is made up of vertical and horizontal crossed wires so as to form meshes. The wires can have a diameter of about half the thickness of the corresponding fluid zone 80. The metallic lattice 9 can be welded to the distribution frames 31, 31′ and the metal sheet 32 using the techniques described above. The metallic lattice 9 can occupy all the vacant space in the fluid zone 80 perpendicular to the stack. As shown in FIG. 3, a single metal sheet 32 is placed between the two distribution frames, acting as a thermal conductor, allowing heat transfer between the hot and cold fluids in the heat exchanger 1. This metal sheet 32 is thin to maximize thermal efficiency. The metal sheet 32 comprises orifices corresponding to those in the two distribution frames 31, 31′.

FIG. 4 shows 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 in the same way as in FIG. 3. Each distribution frame 31, 31′ has an external and an internal contours having zigzag shapes, optimising space for the flow of fluids.

As shown in FIG. 4, a different type of metal sheets 32 can be placed between the two distribution frames 31, 31′. This metal sheet 32 has corrugations 321. These corrugations are inclined with respect to a direction of fluid flow along the metal sheet 32. The corrugations 321 have an angle of inclination of between e.g. 30° and 40° to the plane of extension of the distribution frames 31, 31′. The corrugations 321 may, for example, be sinusoidal or V-shaped.

Advantageously, the corrugations add rigidity to the metal sheet 32, enabling 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 an improved heat transfer by exposing more surface area to the fluid.

The corrugated metal sheets 32 can be manufactured 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.

In summary, the disclosure relates, for example, to a heat exchanger 1 designed to preheat the combustion air, for example, of a micro-turbine in a cogeneration system. The structure of the 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 framing 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 on the distribution frames 31, 31′, simplifying the manufacture of the heat exchanger 1.

The present application may reference quantities and numbers. Unless specifically stated, such quantities and numbers are not to be considered restrictive, but exemplary of the possible quantities or numbers associated with the present application. Also in this regard, the present application may use the term “plurality” to reference a quantity or number. In this regard, the term “plurality” is meant to be any number that is more than one, for example, two, three, four, five, etc. The terms “about,” “approximately,” “near,” etc., mean plus or minus 5% of the stated value. Unless otherwise indicated, the numerical values given as examples are given with a margin of error of 10%. For the purposes of the present disclosure, the phrase “at least one of A and B” is equivalent to “A and/or B” or vice versa, namely “A” alone, “B” alone or “A and B.”. Similarly, the phrase “at least one of A, B, and C,” for example, means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all further possible permutations when greater than three elements are listed.

In the detailed description herein, references to “one embodiment”, “an embodiment”, “an example embodiment”, “one or more embodiments”, “some embodiments”, etc., indicate that the embodiment or embodiments described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment or embodiments. In addition, when a particular feature, structure, or characteristic is described in connection with an embodiment or embodiments, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments. Thus, it will be appreciated that embodiments of the present disclosure may employ any combination of features described herein. All such combinations or sub-combinations of features are within the scope of the present disclosure.

The principles, representative embodiments, and modes of operation of the present disclosure have been described in the foregoing description. However, aspects of the present disclosure, which are intended to be protected, are not to be construed as limited to the particular embodiments disclosed. The embodiments described herein are to be regarded as illustrative rather than restrictive. It will be appreciated that variations and changes may be made by others, and equivalents employed, without departing from the spirit of the present disclosure. Accordingly, it is expressly intended that all such variations, changes, and equivalents fall within the spirit and scope of the present disclosure, as claimed.