DEVICE SUITABLE FOR THERMAL DECOUPLING IN A HEAT EXCHANGER

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(a) to foreign priority patent application EP24383383.7, filed Dec. 17, 2024. The foreign priority patent application is hereby incorporated by reference in its entirety herein, including without limitation: the specification, claims, and abstract, as well as any figures, tables, appendices, or drawings thereof.

TECHNICAL FIELD

The present disclosure relates to a device suitable for thermal decoupling in a heat exchanger. Specifically, the present disclosure relates to a device adapted or designed to establish a barrier to by-pass flow through the space between two spaced-apart surfaces, ensuring improved heat exchanger efficiency.

According to a preferred embodiment, a first surface is the inner surface of a casing and, the second surface is the outer surface of a core of a heat exchanger. In this embodiment, heat recovery is of interest and, for this purpose, heat is transferred from a first fluid, a hot gas, to a second fluid, a gas to be heated. An example of hot gas is the post-combustion gas coming from a gas turbine, for example from among the gas turbines used for electricity generation. An example of a gas to be heated is air.

The heat exchanger comprises a casing housing a core, the core configured for exchanging heat between the first fluid and the second fluid. The by-pass flow barrier provided by the invention prevents the passage of the hot gas from an inlet port of the casing to an outlet port of the casing without passing through the core of the heat exchanger while preventing mechanical stress due to large and non-uniform thermal expansions of the core.

BACKGROUND

In the field of heat exchangers, it is common to encounter challenges related to thermal decoupling and the prevention of bypass flow that may flow between the core and the casing.

Known systems typically involve various sealing mechanisms and structural designs aimed at minimizing thermal losses and ensuring efficient heat transfer. However, these conventional approaches often face limitations in terms of durability, ease of installation, and effectiveness in maintaining a consistent barrier over time.

Another problem not solved by the state of the art is that of establishing a barrier between two surfaces against the passage of a by-pass flow in the face of high degrees of non-uniform expansion.

For instance, gaskets and seals used in traditional heat exchangers can degrade under high temperatures and pressures, leading to leaks and reduced performance. Additionally, the rigid structures employed in some designs may not adequately accommodate thermal expansion and contraction, resulting in mechanical failures or inefficiencies.

According to known practices, achieving a reliable thermal barrier in heat exchangers often requires very complex assembly processes and the use of multiple components, which can increase manufacturing costs and maintenance requirements. Despite the substantial advances in the field of heat exchanger technology, there remains a need for more robust and adaptable solutions that can maintain effective thermal decoupling under varying operational conditions.

Existing designs may also struggle with providing uniform pressure distribution across the sealing surfaces, leading to uneven tensional stress in some pieces and potential points of failure.

In addition, integrating thermal barriers into compact, high-performance heat exchanger configurations presents additional challenges due to space constraints.

It is therefore a technical problem underlying the present invention to provide a device for thermal decoupling in a heat exchanger that at least partially overcomes the disadvantages of known systems.

SUMMARY

It is an object of this invention to provide a device that overcomes one or more of the disadvantages of known systems.

A first aspect of the invention provides a device suitable for, and more particularly adapted for, thermal decoupling in a heat exchanger, in particular for establishing a barrier to by-pass flow through the space left between two surfaces, a first surface and a second surface and both surfaces spaced apart, comprising: a first wall with means adapted for at least resting on the first surface; a second wall with means adapted for at least resting on the second surface; wherein the first wall and the second wall have an overlapping region and, between the first wall and the second wall there are elastic recovery means configured to provide a tendency to maintain a resting force on the first surface and on the second surface.

The subject matter described is a device designed for thermal decoupling in a heat exchanger, particularly to establish a barrier to by-pass flow through the space left between two surfaces, denoted as a first surface and a second surface, which are spaced apart. The device comprises a first wall that includes means adapted for at least resting on the first surface, and a second wall that includes means adapted for at least resting on the second surface. The first wall and the second wall have an overlapping region, and between these walls, there are elastic recovery means configured to provide a tendency to maintain a resting force on both the first and second surfaces.

In this context, thermal decoupling refers to the process of minimizing thermal stress caused by different expansion rates of materials in contact within the heat exchanger. The first surface and second surface are parts of the heat exchanger that are spaced apart, creating a potential gap through which by-pass flow could occur.

The first wall and second wall are structural components of the device that rest on these surfaces to form a barrier.

The overlapping region is the area where the first and second walls overlap, ensuring continuity of the barrier even if there is a differential displacement between the first surface and the second surface. Elastic recovery means are components that provide a restoring force, maintaining a force between the walls against their respective surfaces despite thermal expansion or contraction reducing or increasing the distance between the spaced surfaces. The restoring force prevents the overlapping walls from separating the two spaced surfaces, the first surface and the second surface, which would cause a path for the by-pass flow.

The advantages of this device include the ability to effectively prevent by-pass flow between the core of the heat exchanger and the housing casing, even when there are variations in the distance between the inner surface of the casing and the outer surface of the core due to its thermal expansion. This ensures efficient thermal transfer between the fluids within the heat exchanger since alternative paths to the flow of the first hot fluid are prevented from passing through the core transferring its heat. In addition, the proposed solution reduces the thermal stress on the components.

In an embodiment according to the previously disclosed first aspect of the invention, the first wall, the second wall, or both walls of the device are a plate.

This introduces a specific structural configuration for the walls that rest on the first and second surfaces. According to this embodiment, the manufacturing process is simple, since the shape of the walls is obtained by cutting, bending or stamping operations from raw sheet material.

The new feature brought by this embodiment is the specification of the walls'form as plates, which implies a planar structure, preferably flat. This structural detail can influence the device's performance in terms of stability and contact area with the surfaces. Plates, being flat, can provide a more consistent contact between the overlapped surfaces, enhancing the effectiveness of the thermal decoupling and the barrier to bypass flow.

In addition, according to a specific embodiment, when the two walls show a further resting force of one wall against the other a minimum clearance between the walls is ensured.

This configuration can also simplify the manufacturing process, as plates are a common and easily produced form.

The flat, plate-like walls can also facilitate easier installation and alignment with surfaces, as the shape of the plates can be cut to fit the shape of the surface, ensuring a more reliable and effective thermal decoupling.

In an embodiment according to any of the previously disclosed embodiments, the means for at least resting on the first surface, the means for at least resting on the second surface or both means, are a support plate.

The support plate serves as the means for at least resting on the first surface, the means for at least resting on the second surface, or both means. This feature brings a more defined and potentially more stable interface between the device and the surfaces it is intended to rest upon. By specifying the use of a support plate, the claim enhances the structural integrity and reliability of the device in maintaining its position between the two surfaces.

The support plate can provide a more uniform distribution of the resting force, which is facilitated by the elastic recovery means configured to maintain a resting force on both the first and second surfaces. This uniform distribution can help in reducing stress concentration on the surfaces, thereby extending the lifespan of both the device and the surfaces it interacts with.

Additionally, the support plate can offer a more robust and consistent barrier to bypass flow through the space left between the two surfaces, thereby improving the thermal decoupling efficiency of the heat exchanger.

The introduction of the support plate as a means for resting on the surfaces also implies that the device can be more easily manufactured installed and maintained, as the support plate can provide a clear and stable point of contact. This can be particularly advantageous in applications where the surfaces may not be perfectly aligned or where there may be slight variations in the spacing between the surfaces. The support plate can accommodate these variations and still maintain a secure and effective resting position.

Furthermore, the use of a support plate can potentially simplify the manufacturing process of the device, particularly when the walls are also plates that come from a single original raw plate that is cut and bent to configure the first and second walls as a continuation of the support plate.

In an embodiment according to any of the previously disclosed embodiments, the device comprises: a first profile formed by two first walls joined by means of a first support plate configured to rest on the first surface, configuring said first profile with a ‘U’ shaped transverse cross-section wherein at least one first wall has an overlapping region with the second wall and, the first profile is configured to extend along the longitudinal direction essentially parallel to one of the surfaces, the first surface or the second surface.

This embodiment introduces a device that includes a first profile formed by two first walls joined by means of a first support plate configured to rest on the first surface. This first profile extends along a longitudinal direction and has a ‘U’shaped transverse cross-section.

This first ‘U’-shaped profile forms an interior space that houses elements that are at least partially protected, e.g. the elastic recovery means. According to this example, it is sufficient that at least one of the first walls of the first profile is the wall that overlaps with the second wall.

In an embodiment according to the previously disclosed embodiment, the device further comprises: at least one second profile formed by two second walls joined by means of a second support plate configured to rest on the second surface, configuring said second profile extending along the longitudinal direction and with a ‘U’ shaped transverse cross-section; wherein each first wall has an overlapping region with a second wall and wherein the two profiles are configured to extend along the longitudinal direction essentially parallel to one of the surfaces, the first surface or the second surface.

Additionally, the device includes at least one second profile formed by two second walls joined by means of a second support plate configured to rest on the second surface. This second profile also extends along the longitudinal direction and has a ‘U’ shaped transverse cross-section. Each first wall that exists has an overlapping region with a second wall, and the profiles are configured to extend along the longitudinal direction essentially parallel to one of the surfaces.

The specific structure providing the interaction between overlapping walls involves the structural configuration and interaction of the first and second profiles. The first profile, with its two first walls and first support plate, is designed to rest on the first surface, while the second profile, with its two second walls and second support plate, is designed to rest on the second surface. The overlapping region between each first wall and a second wall ensures two separate barriers preventing the bypass flow.

The ‘U’ shaped transverse cross-section of both profiles adds structural integrity and stability to the device, allowing it to effectively establish a barrier to by-pass flow through the space left between each of the two overlapped surfaces.

In an embodiment according to any of the previously disclosed embodiments, the elastic recovery means rest on the first support plate and on the second support plate adapted to cause the tendency to be spaced apart.

As the first support plate rests on the first surface and the second support plate rests on the second surface, the device adapts its support plates and their respective resting surfaces to the available space between the first and second surfaces.

This configuration enhances the functionality of the device by ensuring that the elastic recovery means maintain the necessary resting force on the first surface and the second surface preventing the appearance of gaps that cause bypass flows.

The introduction of the support plates provides a structured foundation for the elastic recovery means, ensuring that they can perform their function of maintaining the resting force more efficiently over almost the entire support plates. The support plates serve as a stable base, allowing the elastic recovery means to exert a consistent force, thereby improving the overall stability and effectiveness of the thermal decoupling device.

The adaptation of the support plates to cause the tendency to be spaced apart further ensures that the device can accommodate variations in the spacing between the first and second surfaces, providing a more versatile and reliable solution for thermal decoupling in heat exchangers responding to any thermal change, in particular for cores with a “U” configuration, due to the difference in thermal expansion between the two branches.

This enhancement is particularly significant in applications where maintaining a consistent barrier to by-pass flow is critical, as it ensures that the device can adapt to different operational conditions while still providing effective thermal decoupling.

In a further embodiment according to the two previously disclosed embodiments, the at least one second profile is housed inside the first profile.

In this embodiment, this particular configuration introduces a specific structure where the second profile is nested within the first profile. This structural arrangement enhances the interaction between the first and second profiles, as any force between the first and second walls on one side of the profile is transmitted across the profiles to the opposite side, so that a force that causes a reduction in the clearance between the two walls also causes a reduction in the clearance between the two walls on the opposite side of the profiles.

Additionally, the new feature of having the second profile housed inside the first profile brings a more robust structure since the profile housing the other profile is a guide preventing the relative displacement between the two pieces.

Furthermore, the housing of the second profile inside the first profile could provide additional protection to the inner space where the elastic recovery means are housed, being protected from high temperature conditions which could lead to loss of elastic properties, thereby extending the lifespan of the device.

In a further embodiment according to any previously disclosed embodiment, the space between the two profiles is at least partially occupied by an inner filling material, the inner filling material having at least a cavity to house the elastic recovery means.

This feature enhances the device's functionality by providing additional structural integrity and stability to the thermal decoupling mechanism. The inner filling material serves to occupy the space between the profiles and the elastic recovery means, thereby reducing any potential gaps that could compromise the effectiveness of the thermal barrier.

The inner filling material could also potentially provide additional thermal insulation, further improving the device's ability to prevent bypass flow through the space left between the two surfaces.

When the filler material is a heat-insulating material, then the heat transfer from the hot gas into the spring space is drastically reduced, preventing the spring from reaching excessively high temperatures that would degrade its elastic properties.

In a further embodiment according to any previously disclosed embodiment, the elastic recovery means, preferably a spring, comprise a spring housed in a sleeve.

This embodiment introduces a specific configuration for the elastic recovery means, which comprise a spring housed in a sleeve. The elastic recovery means are designed to exert a force that maintains the resting force on both the first and second surfaces. The inclusion of the sleeve serves as a housing for the elastic recovery means, which likely provides additional stability and protection, specifically when the elastic recovery means are one or more springs, ensuring it remains in the correct position and operates effectively.

This protection extends to the extreme conditions in the hot gas inlet regions, both due to the high temperatures and the gas composition that could degrade the elastic properties of the spring. The presence of the sleeve prevents the spring from being exposed to such conditions and factors which can lead to a more reliable and long-lasting device.

This configuration ensures that the spring can function optimally within the device, maintaining the necessary force to keep the first and second walls in contact with their respective surfaces. This detailed protecting mechanism, specifically the spring and the sleeve housing the spring, enhances the device's ability to provide a consistent and effective thermal decoupling barrier.

In a further embodiment according to any previously disclosed embodiment, the first surface, the second surface or both are formed by fins arranged consecutively and separated from each other forming channels;

• • between the fins there is arranged a first filling material, preferably in the form of a bead stretched along the channel formed between fins, in such a way that the support with the device is with the intermediary of the first filling material.

According to this embodiment, the core is formed by fins arranged consecutively and separated from each other to form channels. The set of fins increases the efficiency of the heat exchanger but, at the location of the device causes bypass flow through the channels caused by the fins if no additional technical solutions are not used. According to this embodiment, a first filling material is arranged between the fins in such a way that the support with the interposition of said first filling material. This means that the first filling material occupies the available space in the channel configured between two fins and therefore acts as a barrier against the bypass flow.

This configuration enhances the device's adaptability to different heat exchanger designs by allowing it to interface with surfaces that are not continuous but rather segmented by fins. According to this embodiment, the device further comprises a first filling material, preferably in the form of a bead, which is stretched along the channels formed between the fins. This filling material serves as an intermediary, facilitating the support of the device on the fins.

This intermediate filling material increases the stability and effectiveness of the resting force exerted by the device on the fins and ensures that the elastic recovery means can work optimally, since the shape of the resting surface directly in contact with the support can be matched by means of the first filling material.

In a further embodiment according to any previously disclosed embodiment, the device comprises a second filling material in laminar form that is interposed between the device and the first filling material.

This embodiment introduces a second filling material in laminar form that is interposed between the device and the first filling material. This addition involves the interaction between the second filling material and the first filling material as well as the device itself. The second filling material, being in laminar form, according to a preferred embodiment is flat, which allows it to be easily placed between the device and the first filling material. This laminar form facilitates a more uniform distribution of any forces or pressures exerted by the device onto the first filling material also absorbing any shape perturbation caused by the fins and the first filling material filling the channels between the fins. That is, additionally the second filling material can act as a cushion or buffer, absorbing any minor movements or vibrations that may occur between the device and the first filling material. This can prevent wear and tear on both the device and the first filling material, thereby increasing the longevity and durability of the heat exchanger system.

The presence of the second filling material also causes that the support is not in direct contact with the end of any fin reducing the stress.

In a particular implementation of the heat exchanger, the heat exchanger comprises: a core formed by stacking a plurality of heat exchanging hollow plates where each heat exchanging hollow plate comprises at least one chamber with peripheral fins; at least one conduct passing through the at least one chamber of the plurality of heat exchanging hollow plates; a casing housing the core such that: the casing has an inlet port for the inlet of a first fluid, preferably a hot gas and, an outlet port for the outlet of the first fluid; the core is interposed between the inlet port and the outlet port to interpose itself in operational mode to the flow of the first fluid; the at least one conduit is in fluidic communication with an inlet and an outlet outside the casing for a second fluid, preferably a cold gas to be heated; a device for thermal decoupling according to any one of the preceding disclosed embodiments, extending along a peripheral path around the core (C) and arranged between the core and the casing to establish a barrier to the passage of the bypass flow wherein the first surface is the inner surface of the casing and the second surface is the outer surface of the core.

The new features brought by this heat exchanger include the detailed structure of said heat exchanger, such as the stacking of hollow plates with peripheral fins, the inclusion of at least one conduit passing through the chambers of the hollow plates, and the specific arrangement of the core within the casing. These features cause the heat exchange between the first and second fluids and enhances the efficiency by establishing a barrier to bypass flow through the thermal decoupling device. The arrangement of the core and the casing, along with the fluidic communication of the conduit, ensures that the heat exchanger operates effectively in its intended application.

In a further embodiment according to any previously disclosed embodiment, the peripheral path along which the device extends is straight in sections.

This structure where the peripheral path is straight in sections allows to adapt to the plates and shape of a core formed by stacking chambers. These faces are either flat or are formed by consecutively arranged fins that define, at least in sections, straight sections. In this way, the device adapts to each of the sections increasing the efficiency in its function as a barrier to the passage of bypass flow.

In a further embodiment according to any previously disclosed heat exchanger, said heat exchanger has two conduits and each heat exchanging hollow plate has two chambers being both chambers fluidically connected, and wherein a conduit passes through a first chamber of each heat exchanging hollow plate of the stack and, the other conduit passes through a second chamber of each heat exchanging hollow plate and, where a conduit and the other conduit are fluidically connected through the plurality of hollow plates giving rise to either a “U” configuration or a “Z” configuration for the second fluid and establishing a more compact core.

According to this embodiment, the heat exchanger incorporates two conduits and each heat exchanging hollow plate has two chambers. Specifically, one conduit passes through the first chamber of each heat exchanging hollow plate in the stack, while the other conduit passes through the second chamber of each heat exchanging hollow plate. According to this embodiment the two conduits are essentially parallel.

The second fluid in one chamber of a hollow plate is in fluidic communication with the other chamber of the same hollow plate. In this way, the second fluid that enters through the conduit passing through each of the first chambers of the stack of hollow plates is transferred to the second chamber for each hollow plate and finally the second conduit collects the flows that have passed to the second chamber of each hollow plate.

In the preferred example the thickness of the two chambers of each hollow plate is greater than the thickness of the area where the fluidic communication between chambers is located. The thickness of the hollow plates are extended in the staking direction. The space between two adjacent hollow plates in the area of reduced thickness, i.e. where the fluid communication between the chambers takes place, is where the main heat exchange surface between the two fluids exist. The rest of heat exchange surface is around the first and second chambers.

When the stack is in idle mode because there is no hot gas inlet, the expansion of all the chambers is the same. On the contrary, when in operating mode there is a flow of hot gas passing through the outside of the core, the hot gas heats the entire stack, both on the side where the first chambers are located and, on the side, where the second chambers are located. However, the temperature of the first chambers in this operating mode is cooler since the second fluid that receives the heat enters cold in all the first chambers but leaves hotter in the return flow through the second chambers.

This means that the stack of the first chambers with a lower temperature has a lower degree of thermal expansion in the stacking direction than the side of the stack where the second chambers are located. The result is an inhomogeneous expansion that must be compensated for because the spacing between the core and the inner surface of the casing is no longer the same in operating mode but, in the preferred embodiment is the same when at idle mode and cold.

This is the main function of the thermal decoupling device placed around the core so that the hot flow of the first fluid impinges on one side of the core and passes through the spaces left by the fluidic passages of the hollow plate stack transferring heat through the large exchange surface provided by this configuration.

Likewise, the thermal decoupling device not only compensates for variations between the outer surface of the core and the inner surface of the casing along a closed path but also prevents the event of bypass flow in any of the operating conditions.

The ‘U’ configuration is the configuration shown when the entry of the second fluid into the first conduit, the one that feeds the first chambers, occurs at an end located on the same side of the core where the exit of the same second fluid occurs through the second conduit, the one that collects this second fluid from the second chambers.

The ‘Z’ configuration is when this outlet of the second fluid in the second conduit is not on the same side but on the opposite side of the core.

The “U” or “Z” configuration for the second fluid results in a much more compact core because the outward and return flow path of the second fluid is set along the same length and, heat exchange also occurs in the region between the first chamber and the second chamber further increasing the exchange area.

BRIEF DESCRIPTION OF THE DRAWINGS

Several embodiments in which the present disclosure can be practiced are illustrated and described in detail, wherein like reference characters represent like components throughout the several views. The drawings are presented for exemplary purposes and may not be to scale unless otherwise indicated.

FIG. 1: This figure shows schematically a first example of realization where the first surface, the second surface and the overlapping walls causing the barrier against the bypass flow are shown. The same figure shows schematically the elastic recovery means. At the top is shown a trihedron with the three main directions to be used in the description.

FIG. 2: This figure schematically shows a second embodiment with two pairs of walls and a support plate for each pair of walls so that two “U” profiles are configured. According to this embodiment the two “U” profiles show the same overlapping order.

FIG. 3: This figure schematically shows a third embodiment as in the previous figure but, one “U” profile shows a smaller section such that one “U” profile houses the other “U” profile.

FIG. 4: This figure schematically shows a fourth embodiment wherein a profile extending according to a longitudinal direction (and comprises an inner filling material with cavities for housing the elastic recovery means. This same figure shows a more complex example where there are two alignments of profiles with inner filling material.

FIG. 5: This figure schematically shows a fifth embodiment as shown in FIG. 3, where now the second surface is formed by a sequence of fins located at the ends of the hollow plates giving rise to channels. These channels are filled with a first filling material.

FIG. 6: This figure schematically shows a sixth embodiment as shown in FIG. 5, wherein the second surface formed by a sequence of fins filled by a first filling material shows a second filling material in the form of a mat or flat structure.

FIG. 7: This figure schematically shows a view of the main elements forming a heat exchanger according to an example embodiment as well as of an embodiment of a thermal decoupling device such as those described. Additionally, the same figure shows schematically on the right a section of a hollow plate with the perimeter fin structure.

An artisan of ordinary skill in the art need not view, within isolated figure(s), the near infinite distinct combinations of features described in the following detailed description to facilitate an understanding of the present disclosure.

DETAILED DESCRIPTION

The present invention, according to the first inventive aspect, is a thermal decoupling device.

Turning to FIG. 1, this figure schematically shows two surfaces, a first surface (1) and a second surface (2) spaced apart. In operational mode, the first surface (1) is the inner surface of the casing (S) and the second surface (2) is the outer surface of the core (C) of the heat exchanger formed by stacking a plurality of hollow plates. The structure of the heat exchanger will be described in more detail below making use of FIG. 7.

The first surface (1) and the second surface (2) are spaced according to a separation direction d as shown by the trihedron located at the top of FIG. 1. In turn, one and the other surface (1, 2) extend according to two directions perpendicular to each other identified as f and l, and perpendicular to the separation direction d.

It is between the first surface (1) and the second surface (2) that there is a space allowing a bypass flow unless impeded, such as occurs by the presence of the device (3) for thermal decoupling, for example according to the embodiments described.

FIG. 1 shows the essential elements of the device (3), a first wall (3.1) with means adapted to at least rest on the first surface (1) and, a second wall (3.2) also with means adapted to at least rest on the second surface (2). The means for resting on the first surface (1) and on the second surface (2) are identified in this embodiment as a support plate (3.3, 3.4) resting against one and the other surface (1, 2).

In this embodiment the support plate (3.3, 3.4) and the corresponding wall, either the first wall (3.1) or the second wall (3.2), are fixed to each other maintaining a perpendicular angle. In this way, the first wall (3.1) and the second wall (3.2) are positioned essentially parallel and with an overlap region (R).

This overlapping region (R) ensures that, in the event of a variation in the spacing between the first wall (1) and the second wall (2), a barrier is maintained between the two walls (1, 2) that prevents the bypass flow from passing through.

Additionally, the device (3) comprises elastic recovery means (3.5) responsible for maintaining a tendency for the first wall (3.1) to be resting on the first surface (1) and the second wall (3.2) to be resting on the second surface (2).

Preferred embodiments of the elastic recovery means (3.5) are one or more springs, one or more elastic straps or one or more leaf springs.

FIG. 2 shows the same elements as in FIG. 1 where now the support plates (3.3, 3.4) resting against the first surface (1) and the second surface (2) have two walls, one support plate (3.3) having two first walls (3.1) and the other support plate (3.4) having two second walls (3.2) such that two profiles (P1, P2) are configured with a “U” configuration with the walls of the “U” profile facing the other “U” profile.

In this embodiment example the two profiles (P1, P2) are the same such that, following the orientation of the figure, the two first walls (3.1) are located above the two second walls (3.2).

FIG. 3 inherits all the elements described in FIG. 2, hence the descriptions of common elements are valid for this figure.

In FIG. 3 the two profiles (P1, P2) are different, the profile on the left (P1) is somewhat wider than the profile on the right (P2) so that the profile on the left (P1) completely houses the profile on the right (P2).

FIG. 4 shows the longitudinal direction l in which a “U” profile is extended with an inner filling material (3.6) that prevents the inner space of the profiles (P1, P2) from easily allowing the first fluid, the hot gas, to pass through if it manages to overcome the barrier formed by the overlap between the first wall (3.1) and the second wall (3.2).

In this same figure it is observed that the inner filling material (3.6) shows a plurality of cavities of circular plan view, that is, of cylindrical configuration, to house springs. These springs are the specific shape in this embodiment of the elastic recovery means (3.5). Additionally, in this embodiment the springs are protected since they are housed inside a sleeve (3.7).

If the inner filling material (3.6) is chosen to be thermally insulating, the springs are further protected against the high temperatures of the hot gas which could degrade their elastic properties.

The lower part of FIG. 4 shows an embodiment in which there are arranged two profiles arranged adjacent and consecutive as shown in the upper part of the same figure establishing a double barrier.

FIG. 5 inherits all the elements described in FIG. 3 hence the descriptions of common elements are valid for this figure.

In FIG. 5 the second surface (2), the outer surface of the core (C) of a heat exchanger, is a surface formed by stacking a plurality of hollow plates (C1) in which, in the perimeter zone, there are fins (C1.4) that increase the heat exchanging ability by increasing the contact area with the surrounding fluid.

These fins (C1.4) are arranged consecutively forming channels (CH) which, if no size is adapted, are preferential paths for the fluid and would give rise to a bypass flow.

To prevent the passage of bypass flow, according to this embodiment, in the channels (CH) a first filling material (M1) is introduced so that the second surface (2) is formed by this first filling material (M1) since preferably the first filling material (M1) is sufficient to protrude to a greater degree than the fins (C1.4).

In this way, the support plate (3.4) on the right rests on the first filling material (M1) and not directly against the edges of the fins (C1.4). If this were the case, if there were direct contact, vibrations, lack of sufficient support on the first filling material (M1) and mechanical fatigue would occur both on the edges of the fins (C1.4) and on the support plates (3.4).

FIG. 6 inherits all the elements described in FIG. 3 hence the descriptions of common elements are valid for this figure.

This FIG. 6, on the right, shows the surface formed by stacking the stacked hollow plates (C1), with the channels (CH) formed and, as shown in FIG. 5, filled by the first filling material (M1).

Additionally, the surface generated by the first filling material (M1) is covered by a second filling material (M2) which, in this embodiment example has the configuration of a mat.

Both the first filling material (M1) and the second filling material (M2) are made of a compressible material so that they allow deformation to adapt to the shape of adjacent surfaces that may be generating a pressure force.

In the case of the first filling material (M1) the configuration is in the form of elongated portions that are housed inside the channel (CH). These portions are deformed into the shape of the channel imposed by the ends of the stacked hollow plates ending in a fin (C1.4).

In turn, these portions of the first filling material (M1) give rise to an alignment of elongated protrusions rather than a flat surface. The second filling material (M2) and configured in the form of a mat, has on one side the flat surface of the support plate (3.4) and, on the opposite side the alignment of elongated protrusions. The deformation ability of the second filling material adapts to the external shape of these elongated protrusions avoiding that the irregular surface resulting from the first filling material (M1) causes new channels that would allow the bypass flow to pass.

This solution based on the second filling material (M2) in the form of a mat is also applicable to the opposite flat support plate (3.3) which is facing a flat surface such as the inner surface of the casing (S).

FIG. 7 shows a heat exchanger in schematic form where a device (3) is incorporated from among those described above.

The heat exchanger comprises a casing (S) showing, in the upper left part of the figure, an inlet (S1) of a first fluid, a hot gas.

An example of hot gas is the gas coming from a gas turbine and from which it is desired to recover heat by transferring its thermal energy to a second fluid. An example of a second fluid is air, for example to be used in the gas turbine in a heat recovery configuration.

The hot gas enters into the casing (S) through an inlet port (S1). The casing (S) houses in its interior a heat exchanging core (C) such that, the passage of the hot gas through the core (C) allows to transfer its heat. After the hot gas passes through the core (C), the gas reaches an outlet port (S2) through which it exits the heat exchanger.

According to the orientation of FIG. 7 the hot gas flow enters into the upper part and exits out of the lower part shown on the right of the casing (S).

The core (C) of the heat exchanger is a stack of hollow plates (C1) that allow the hot gas to pass through it, also transferring heat. The second fluid circulates inside the hollow plates and receives the heat transferred by the first fluid, raising its temperature.

In this case, the second fluid enters into a first conduit (C2), is distributed along the entire stack of hollow plates (C1), and exits through a second conduit (C3). A hollow arrow extending from the first conduit (C2) shown at the top of the core (C) to the second conduit (C3) indicates the direction of passage of the second fluid through the hollow plate stack (C1).

In the same figure, a section of a hollow plate (C1) of the stack is shown with a dashed arrow on the right, the section according to a plane passing through the line of symmetry of the heat exchanger, to allow observation of the inner structure of the hollow plate (C1).

Each hollow plate (C1) comprises two chambers (C1.1, C1.2), a first chamber (C1.1) is shown in the upper part of the figure and, the second chamber (C1.2) is shown in the lower part of the figure. Both chambers (C1.1, C1.2) are fluidically connected by means of a narrowed zone. The structure of the hollow plate (C1) is flat because the two chambers (C1.1, C1.2) are flat and so is the space that fluidically communicates both chambers (C1.1, C1.2). In fact, this intermediate space (C1.3) that fluidically communicates both chambers (C1.1, C1.2) is delimited by two flat walls with a smaller distance than the flat walls of both chambers (C1.1, C1.2).

In the chambers (C1.1, C1.2) shown in section the fluid communication with the two conduits (C2, C3) for the inlet and outlet (of the second fluid are shown schematically on the right section using dashed lines.

According to a “U” configuration for the second fluid, the second fluid enters the first conduit (C2) in a certain direction. For example, in FIG. 7, the first fluid enters the first conduit in a direction perpendicular to the plane defined by the paper in which the figure is shown. The direction in this case is “entering the paper”. After passing through the core (C), which is led from the set of first chambers (C1.1) to the set of second chambers (C1.2) through the space (C1.3) between the stacked hollow plates (C1), the second fluid converges in the second conduit (C3) and exits. If the exit of the second fluid is in the direction “coming out” of the paper plane, a “U” configuration is used. If the exit of the second fluid is in the direction “going into the paper”, coming out of the heat exchanger on the opposite side hidden by the core (C) in FIG. 7, then a “Z” configuration is used.

The first fluid must pass through the stack of hollow plates (C1), in particular using the space caused by the narrowed zone in the intermediate space (C1.3), so, any space between the core (C) and the inner surface of the casing (S) must include a barrier to the passage of the hot gas flow since, if there is any passage the hot gas will tend to go through this passage as it encounters less resistance than passing through the stack of hollow plates (C1). This is the bypass flow that is prevented by the thermal decoupling device (3).

The passages to be prevented are those shown on the right and left of the core (C), with an enlargement at the left side of FIG. 7, as well as in the planes parallel to the plane defined by the drawing paper plane where the figure is represented. The latter is the one that allows to show schematically four circles. That is, the thermal decoupling device (3) comprises four straight segments or sections, one for each space between the outer surface of the core (C) and the inner surface of the casing (S) giving rise to four straight sections configuring a closed path.

The decoupling device (3), according to a preferred embodiment provides a gas barrier around the core (C) having a width covering the distance defined by the intermediate space (C1.3). According to one embodiment, the width of the decoupling device (3) has a width equal to said distance, and according to other embodiments, said distance is covered by two or more decoupling devices (3) arranged in parallel. The schematic embodiment of FIG. 7 shows two decoupling devices in parallel with a spacing between them that allows to show the intermediate space (C1.3), but the two parallel decoupling devices (3) are preferably without spacing or with an small gap, for example to allow dilatation.

The one or more decoupling devices (3) force to the first fluid, the hot fluid, to pass through the inner space between the hollow plates (C1) in the region of the intermediate space (C1.3) while preventing the bypass flow between the core (C) and the casing (S).

The enlarged detail on the left shows in section the two U-sections of the two profiles (P1, P2), one housing the other (P1, P2). In the view parallel to the paper plane it can be seen that the inside of the profiles (P1, P2) contains an inner filling material (3.6) in which there are four cavities to house four springs, the specific form of elastic recovery means (3.5). Each of the springs is protected by a sleeve (3.7) which surrounds the spring and which in turn is also housed in the cavity of the inner filling material (3.6).

The thermal decoupling device (3) works differently on the sides than on the visible part. The sides are those whose core (C) surface is formed by the fins (C1.4) and therefore is the surface that generates channels (CH). This solution is the one that implements a support as shown in FIG. 6 with a first filling material (M1) and a second filling material (M2).

The surfaces seen, have no channels since the stacking surface is flat in this area but, the chambers (C1.1) directly fed by the inlet (C2) of the second cold fluid are colder than the chambers (C1.2) directly fed by the outlet (C3) where the second fluid has already raised its temperature by receiving the heat transferred by the first fluid. This causes the stack to show different heights on the side of the first chambers (C1.1) with respect to the side of the second chambers (C1.2). The springs of the device (3) thermal decoupling allow to compensate these differences of separation between the core (C) and the inner surface of the casing (S) maintaining at all temperature conditions the overlapping of the lateral walls (3.1, 3.2) of the profiles (P1, P2) and therefore securing the barrier against the passage of the bypass flow.