HYBRID HEAT EXCHANGER COMPRISING A TUBE SECTION AND AN ADDITIVE FABRICATION SECTION

Abstract

The invention relates to a hybrid heat exchanger comprising a 3D-printed central section (1) optimized for high-temperature heat transfer and surrounded by a tubular section (2) designed for lower-temperature heat transfer. The central section is integrated within the tubular section, thereby optimizing heat transfer while reducing production and operating costs. The 3D-printed central section may include finned layers and triply periodic minimum surface area (TPMS) structures to increase the exchange surface area and improve thermal efficiency. The tubular section may consist of several tubes (smooth, corrugated, or finned) arranged around the central section. The assembly is designed for a coaxial arrangement, ensuring uniform distribution of the heat transfer fluid and mechanical or welded fastening.The invention also minimizes heat loss through an optimized configuration and uses different materials adapted to the thermal conditions of each section. A manufacturing process for this hybrid heat exchanger is also described, including additive manufacturing by laser melting and assembly of components by vacuum brazing or welding. [Fig. 2]

Description

Title of the invention: HYBRID HEAT EXCHANGER COMPRISING A TUBE SECTION AND AN ADDITIVE FABRICATION SECTION Background of the invention

[0001] The invention relates to the field of heat exchanger devices and systems, particularly in applications where thermal efficiency and cost reduction are essential. More specifically, it describes a hybrid heat exchanger combining 3D printing technologies using additive manufacturing and tubular heat exchangers, aimed at optimizing heat transfer in different environments while reducing the drawbacks inherent in each technology.

[0002] Thermodynamic systems, long used in commercial and residential applications, facilitate the heating or cooling of a working fluid. These systems generally employ a heat exchanger to change the temperature of the fluid, which is then used for specific functions. For example, in power generation systems with steam engines (also known as the Rankine cycle), counter-current heat exchangers heat the working fluid to power an electric generator turbine.

[0003] Innovative shell and tube heat exchangers are known in the literature. For example, French patent FR3141759 describes a multi-section shell and tube heat exchanger, but it does not include an additively manufactured heat exchanger. Constructing this type of heat exchanger requires very high-temperature brazing, which adds to the manufacturing complexity and the overall product cost. High-temperature brazing also presents several disadvantages, including the risk of cracking or defects at the joints due to thermal cycling, premature material degradation, and poor resistance to high-pressure environments. Furthermore, brazing processes can lead to leaks when thermal stresses are not properly managed, thus compromising the integrity of the heat exchanger during high-temperature operation.The innovation proposed in this patent, which combines additive manufacturing and a traditional tubular section, makes it possible to overcome these limitations while improving thermal performance.

[0004] Although the invention can be used in any type of heat exchange application, it is particularly interesting for high-temperature applications, exceeding 500°C. This makes it particularly suitable for demanding industrial environments, where high-efficiency heat transfer in extreme conditions are necessary, such as in gas turbines, electricity production, or industrial processes requiring high temperatures.

[0005] The invention also applies to the field of turbogenerator devices and systems operating on a gas turbine cycle, intended for motor vehicles. More specifically, it proposes a heat exchanger architecture adapted to these turbogenerators. In this type of application, the heat exchanger is used as a heat recovery unit, allowing the energy at the turbine outlet to be recovered to preheat the combustion chamber inlet, thereby increasing the thermodynamic efficiency of the system.

[0006] Traditionally, a typical heat exchanger configuration uses a "shell and tubes" design for heat exchange. This configuration comprises a plurality of tubes nested inside an outer shell. The working fluid is pumped through the tubes, while the heat source fluid or other heating component is contained within the outer shell. Although this type of configuration is widely used, it exhibits inefficiencies in heat exchange between the heat source fluid and the working fluid, resulting in much larger heat exchange units with lower efficiency. This problem limits the amount of heat transferred to a smaller volume of working fluid than is achievable with modern heat exchanger systems.

[0007] Plate and fin heat exchangers were developed to overcome many of the inefficiencies present in shell and tube heat exchanger designs in terms of thermal performance and compactness. Plate heat exchangers use a plurality of plates and fins arranged adjacent to one another. The working fluid and the heat source are allowed to flow between alternating plates. By allowing this flow between alternating plates, a large quantity of working fluid can be heated in a relatively small space, but very efficiently. As a result, not only is the size of the heat exchanger much smaller, but a larger quantity of working fluid can be heated to a higher temperature compared to traditional technologies.

[0008] Plate and fin heat exchangers, although efficient, also have drawbacks, particularly in terms of pressure losses. These losses are mainly due to two factors: the small hydraulic diameter of the fluid passage channels and the presence of fins, which increase resistance to fluid flow.

[0009] The manufacturing process of the fins is another limitation. The fins are generally made from materials such as aluminum or copper, in due to their good thermal conductivity, but when high-temperature resistant materials, such as stainless steel, titanium, or stainless steel, are used, manufacturing constraints become much more complex. These materials, used in high-temperature and high-pressure environments, require complex brazing techniques, often under vacuum, to ensure the quality of the joints.

[0010] Fin design limitations are also a major problem, especially for high-performance materials. It is difficult to create optimized and complex fin geometries with these rigid materials, which prevents optimal heat transfer.This need to use high-performance materials, combined with the complexity of the manufacturing process, can significantly increase the cost of plate and fin heat exchangers, especially for industrial applications requiring high performance and increased corrosion resistance.

[0011] 3D-printed plate and fin heat exchangers represent a significant advancement over traditional plate and fin heat exchangers. Thanks to 3D printing technology, these exchangers can be designed with a precision and geometric complexity unattainable with conventional manufacturing methods. This allows for much more efficient optimization of fluid flow and heat transfer. Furthermore, 3D-printed exchangers are even more compact, as the technology reduces dead spaces and increases the heat exchange surface area while maintaining a compact structure. Thus, 3D-printed plate and fin heat exchangers offer superior thermal efficiency and occupy an even smaller volume than their traditional counterparts, making them particularly suitable for applications where space is limited and energy efficiency is crucial.

[0012] However, each technology has distinct limitations. 3D-printed heat exchangers, while highly efficient, are expensive to produce, especially on a large scale. Their manufacturing complexity and the need for specialized materials to withstand high temperatures increase costs, limiting their use to niche applications.

[0013] Tubular heat exchangers, on the other hand, are much less expensive to produce and are commonly used in many industrial applications, especially when designed for low temperature levels with an inexpensive brazing process. However, their thermal efficiency is lower, particularly at high temperatures, which can lead to energy losses and a reduction in overall system performance.

[0014] Moreover, at these high temperatures, traditional tubular or plate and fin heat exchangers present significant brazing problems, which can lead to leaks and compromising system integrity, especially for high-temperature applications, making their use less reliable in demanding thermal environments.

[0015] For moderate temperatures (below 450°C), soft soldering, using alloys such as copper or silver, is generally sufficient. This process, carried out at relatively low temperatures, is more economical but less suitable for high-temperature applications, as components such as joints can become brittle or break under the effect of heat.

[0016] For high-temperature applications (above 450°C and up to 650°C), brazing is required. This process uses high-performance alloys, such as nickel or gold alloys, and is carried out at higher temperatures (up to 1000°C). Vacuum brazing is often required to prevent oxidation. This method is much more expensive due to the materials used and the complexity of the equipment, thus increasing the overall cost of the heat exchanger.

[0017] Above 650°C, even more sophisticated solutions such as diffusion brazing may be required. This technique creates extremely strong joints but requires lengthy and complex processing conditions, which significantly increases production costs.

[0018] It follows from the above that there is a need for an improved heat exchanger. More specifically, it is necessary to have a high-temperature heat exchanger offering better heat transfer and increased sealing, while being lighter and less expensive. GENERAL DESCRIPTION OF THE INVENTION

[0019] The invention aims to combine the advantages of both technologies by proposing a hybrid heat exchanger. This combination optimizes high-temperature heat transfer with a central section manufactured by additive manufacturing using 3D metal printing, while using tubular exchangers to manage low-temperature heat transfer.

[0020] The main objective of this invention is to reduce the production and operating costs of heat exchangers while maintaining or increasing their overall thermal efficiency. By integrating 3D-printed sections only where they are most needed, the invention reduces costs while maximizing performance.

[0021] The proposed hybrid heat exchanger consists of two main sections: a central section made by metal additive manufacturing in 3D printing located at the heart of the exchanger, surrounded by a tubular section.

[0022] The 3D-printed section is optimized to handle high-temperature heat transfer, where thermal efficiency is most critical. It is designed in the middle of the structure to maximize the heat exchange surface area while minimizing heat loss by convection and radiation.

[0023] The tubular section, on the other hand, is used for heat transfer at lower temperatures. This section is designed to be economical and easy to produce, requiring inexpensive brazing, thus reducing the overall costs of the heat exchanger.

[0024] The integration of these two technologies makes it possible to create a heat exchanger that is efficient, economical, and durable. The hybrid exchanger combines the high performance of 3D-printed sections with the reliability and low cost of tubular exchangers.

[0025] One of the main advantages of the hybrid heat exchanger is the significant reduction in production costs. By using 3D printing only where necessary, manufacturing costs are considerably reduced compared to a fully 3D-printed exchanger.

[0026] Furthermore, the use of tubular technology for low-temperature sections reduces leakage and brazing problems, which are often associated with high-temperature heat exchange. This improves the reliability and durability of the heat exchanger.

[0027] The invention also allows a reduction in the weight and volume of the exchanger, which is particularly important for applications where space and weight are critical constraints, such as in aerospace or automotive.

[0028] Furthermore, the hybrid heat exchanger offers flexibility in the choice of materials. The 3D-printed section can be manufactured from materials optimized for high temperatures, while the tubular section can use less expensive materials, suitable for lower temperatures.

[0029] The hybrid heat exchanger according to the invention may also include one or more of the following features, which may be combined: • The 3D printed central section and the tubular section can be arranged coaxially, ensuring uniform distribution of the heat transfer fluid. • The 3D printed section can be modular, allowing for its replacement or adaptation according to the specific needs of the application. • The tubular section can also be made using other low-cost heat exchanger technologies, such as tube and fin, plate and fin exchangers, or any other suitable technology. • The tubes of the tubular section can be arranged in a spiral around the 3D printed central section, thus maximizing the efficiency of heat exchange. • The central plate and fin section can also be formed by other heat exchange technologies, such as primary surface exchangers, tetrahedral structures, TPMS (Triply periodic minimal surfaces) structures, or any other technology. • The hybrid heat exchanger is designed to minimize heat loss by convection and radiation, thanks to the central placement of the 3D printed section surrounded by the tubes. • The overall dimensions of the heat exchanger can be adjusted according to the needs of the installation, thus offering integration flexibility. • The hybrid heat exchanger can be compatible with a wide range of heat transfer fluids, including water-based, oil-based or gas-based fluids.

[0030] In a particular embodiment of the invention, the 3D printed section of the hybrid heat exchanger can be integrated into the overall structure by two main methods: by mechanical fixing using bolts, or by direct welding to the structure.

[0031] When the printed part is fixed by bolts, this offers the advantage of a modular and demountable solution. This method allows for easy replacement of the printed section for maintenance or technological upgrades, without having to modify the entire structure. The fixing points are strategically placed to ensure a homogeneous distribution of mechanical and thermal stresses, thus guaranteeing a robust connection while minimizing the risk of deformation or leakage. This type of fixing is particularly advantageous in environments where frequent adjustments or replacements are necessary.

[0032] In a particular embodiment of the invention, the 3D-printed portion of the hybrid heat exchanger is produced using plate and fin technology, where alternating layers of hot and cold fluids are printed. This approach allows for the creation of complex geometries, such as offset, corrugated, or other fin configurations. These structures are specifically optimized for 3D printing and cannot be manufactured using traditional methods, thus offering superior thermal performance and increased compactness.

[0033] 3D printing also allows for local adjustment of the fluid passage cross-section according to variations in temperature and density of the fluids circulating in the exchanger. When the fluid temperature increases, causing expansion, the passage cross-section can be enlarged to maintain optimal flow while minimizing pressure losses. Conversely, when the temperature decreases and the fluid contracts, the cross-section of the passages can be reduced to optimize fluid flow and maximize thermal efficiency. These localized adjustments are made possible by the flexibility of 3D printing, which allows for the design of structures impossible to create using conventional manufacturing techniques.

[0034] The fins, shown in [Fig. 5], whether staggered, corrugated, or of other shapes, increase the heat exchange surface area and promote flow turbulence, thus improving heat transfer without significantly increasing the volume of the exchanger. Furthermore, the printed geometries minimize fluid stagnation areas, reducing heat loss and increasing the overall efficiency of the system.

[0035] Optimizing the dimensions of the extended surfaces, specifically for 3D printing, maximizes thermal performance while minimizing the weight and volume of the heat exchanger. This is particularly advantageous for industrial applications where space and weight are critical constraints.

[0036] In a particular embodiment of the invention, the tubular portion of the hybrid heat exchanger can be formed from smooth, corrugated tubes or tubes equipped with external or internal fins to improve heat transfer. This configuration allows the tube geometry to be adapted to specific thermal requirements, offering greater flexibility to meet thermal and hydraulic performance requirements in various applications.

[0037] The tubular portion may consist of a single uniform section of tubes, or of successive sections of tubes in series. In this embodiment, each successive section is optimized to adjust the fluid passage area according to variations in temperature and fluid velocity. For example, the initial sections may have larger passage diameters to compensate for the thermal expansion of the fluid, while the subsequent sections, where the fluid cools and contracts, may have smaller diameters to maintain a regular flow and minimize pressure losses.

[0038] This configuration maximizes the thermo-hydraulic performance of the heat exchanger by dynamically adjusting the flow parameters at each stage of the process. The external fins added to the tubes increase the contact area with air or another cooling fluid, thus improving heat transfer without requiring an increase in the overall volume of the heat exchanger.

[0039] Tubes with internal and / or external fins ([Fig.6]), meanwhile, promote turbulence in the fluid, further increasing the efficiency of heat transfer while maintaining a compact design.

[0040] This ability to locally adjust the cross-section of the fluid passages and to integrate various tube geometries allows the heat exchanger to operate optimally in environments where thermal management must be particularly efficient. Brief description of the drawings

[0041] The invention will be better understood and other features and advantages will become more apparent upon reading the description given below by way of purely illustrative and non-limiting examples, with reference to the accompanying drawings in which:

[0042] [Fig. 1] presents a hybrid exchanger according to the invention, shown in perspective view;

[0043] Figure 2 shows a cross-sectional view of a version of the hybrid heat exchanger, where we can observe the part produced using additive manufacturing with 3D metal printing in the center, surrounded by the tubes. This configuration clearly shows the central arrangement of the 3D printed structure, optimized for heat transfer at high temperatures, while the outer tubes provide additional heat exchange at lower temperatures.

[0044] Figure 3 illustrates a variant of the hybrid heat exchanger, shown without the central section for clarity

[0045] Figure 4 shows a detailed view of an example of a 3D-printed heat exchanger, Composed of layers of fins separated by plates, this design optimizes heat transfer by increasing the exchange surface area while maintaining a compact structure. The alternating layers of plates and fins promote a smooth fluid flow and efficient heat dissipation.

[0046] Figure 5 shows an example of the embodiment of a layer of the plate heat exchanger and fins, equipped with corrugated fins

[0047] Figure 6 shows an example of an embodiment of a tube equipped with fins. internal and external.

[0048] Figure 7 presents another design example for the printed central section in 3D. Instead of a plate and fin inspired design, the design now uses triply periodic minimal surfaces (TPMS).

[0049] Figure 8 presents another design possibility, where the external shape of The heat exchanger is no longer limited to a cubic structure but can be manufactured in a cylindrical shape. This cylindrical configuration offers greater design flexibility, allowing for better adaptation to various industrial applications where space and shape constraints are critical. The cylindrical shape also optimizes fluid flow around and through the heat exchanger, improving thermal performance while reducing pressure losses. This design integrates easily into compact systems and contributes to a homogeneous distribution of heat transfer.

[0050] DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

[0051] Figures 1 and 2 show a hybrid heat exchanger according to the invention, comprising a 3D printed central section 1 surrounded by a tubular section 2. The 3D printed central section (1) and the tubular section (2) are arranged coaxially to ensure uniform distribution of the heat transfer fluid.

[0052] The 3D-printed central section (1) consists of layers of fins separated by plates, increasing the heat exchange surface area. This maximizes heat transfer in high-temperature areas.

[0053] The fins are 3D printed with complex geometries such as corrugated or offset fins, impossible to manufacture by conventional methods, the 3D printed central section is integrated into the tubular section, which optimizes heat transfer at high temperature while reducing production and operating costs.

[0054] In one of the variants, the section produced by additive manufacturing in 3D printing can include variable sections, in which the section of the hot fluid that is cooling down narrows, while the section of the cold fluid that is heating up widens throughout the heat exchange path.

[0055] In this variant, the fluid inlet Fl, visible in [Fig. 1], is located on the outer surface of the heat exchanger, which is generally used for the cold fluid. This configuration minimizes heat loss between the heat exchanger and the environment, thus reducing the need for specific thermal insulation for very high temperatures.

[0056] Similarly, the fluid outlet Fl, designated Fl-E ("E" for "exit" in English), is located in the center of the exchanger, which also helps to limit heat losses and optimize the overall efficiency of the system.

[0057] The heat exchanger is configured for counter-current fluid flow, improving heat transfer efficiency. The hot fluid inlet F2 is located in the center of the exchanger, thus creating a counter-current heat exchanger. This type of design significantly improves the thermal performance of the exchanger. In a counter-current heat exchanger, the two fluids flow in opposite directions, allowing for more efficient heat transfer. Unlike a co-current heat exchanger, where the temperatures of the two fluids quickly converge, the counter-current heat exchanger maintains a greater temperature difference over the entire exchange, thus maximizing heat transfer between fluids and increasing energy efficiency.

[0058] Figure 2 illustrates the operation of a hybrid heat exchanger according to the invention, in which two fluids enter respectively through the Fl-I and F2-I inlets (I design inlet). According to one embodiment of the invention, these fluids then flow through alternating layers within the 3D-printed section, which consists of plates and fins. Inside the exchanger, the fluids circulate in separate channels, created by alternating layers of plates and fins, thus allowing heat exchange between the fluids without them mixing.

[0059] Once the heat transfer has been carried out in the 3D printed section, the hot fluid, after giving up some of its heat, is discharged through outlet F2-E1 and then circulates in the spaces between the tubes of the tubular section SI for further heat exchange with the Fluid Fl.

[0060] The fluid Fl, after circulating inside the tubes in sections S1 and S2, finally exits section 3 and flows into the 3D-printed section. The central 3D-printed section (1) is made from materials optimized for high temperatures, while the tubular section (2) uses materials suitable for lower temperatures. This configuration maximizes heat exchange efficiency by utilizing the 3D-printed section for high temperatures and the tubular section for additional cooling.

[0061] Furthermore, the tubular section (2) comprises one or more tube sections (S2.1, S2.2, S2.3) arranged around the central 3D-printed section. The tubes may be smooth, corrugated, or finned. The number of tube rows in each section is adjustable, allowing the flow area and heat exchange surface to be tailored to the specific application requirements. This modularity provides precise control over the heat exchanger's thermal performance in response to temperature variations, flow rate, and heat transfer requirements, while also enabling better adaptation to operating conditions.

[0062] Figure 3 shows a variant of the hybrid heat exchanger, illustrated without the 3D-printed central section for clarity. This variant consists of a secondary tubular heat exchanger composed of three distinct sections: S2.1, S2.2, and S2.3. Each section, as shown in the figure, consists of a different number of tubes, allowing the heat exchange surface area and fluid flow cross-section to be adjusted according to the specific requirements of each application.

[0063] Sections S2.1, S2.2 and S2.3 can also be made from different materials or use specific brazing methods, depending on the thermal and mechanical stresses encountered. For example, a section exposed to higher temperatures can be made using a heat-resistant alloy. heat, while a section operating at lower temperatures can be constructed with lighter or more economical materials.

[0064] This modular design allows for the optimization of the heat exchanger's thermal and hydraulic performance. By adapting the number of tubes and the materials used in each section, it is possible to maximize heat transfer while minimizing pressure losses. Furthermore, this configuration offers great flexibility to meet a variety of industrial applications, allowing for precise adjustments based on specific operational requirements.

[0065] Figure 3 shows in detail the direction of fluid flow Fl. Taking a turbogenerator cycle as an example, cold, high-pressure compressed air exits the compressor and enters the heat exchanger at its Fl-I end. The high-pressure fluid enters the tubes in section S3. The connection between sections S2.3 and S2.2 forms a settling chamber located at the bottom of the heat exchanger, designated CT2-3. Another settling chamber, CT1-2, is present in this variant, allowing the three sections to be formed. In this configuration, the flow follows a U-shape, which can be adapted according to the dimensions of each section, particularly its width, length, and height.

[0066] Figure 4 shows a detailed view of an example of a 3D-printed heat exchanger consisting of layers of fins separated by plates. This design optimizes heat transfer by increasing the exchange surface area while maintaining a compact structure. The alternating layers of plates and fins promote a smooth fluid flow and efficient heat dissipation.

[0067] Figure 5 shows a type of corrugated fins

[0068] Figure 6 shows a tube with fins internally and externally

[0069] Figure 7 presents a variation of the invention, using TPMS structures (Triply Periodic Minimal Surface) to optimize heat transfer.

[0070] These structures offer several advantages for 3D-printed heat exchangers, including an exceptionally high heat exchange surface area relative to the total volume, thus optimizing heat transfer. Furthermore, they ensure uniform flow distribution across the exchanger and minimize dead zones where the fluid could stagnate, thereby improving the overall efficiency of the system.

[0071] TPMS are particularly effective at optimizing heat transfer by creating continuous, interconnected, and complex channels that facilitate better fluid circulation. This results in increased thermal performance while maintaining low hydraulic resistance. Furthermore, these structures exhibit high mechanical robustness despite their light weight, thus reducing the mass of the heat exchanger without compromising its resistance to thermal stresses and mechanical. Thus, the 3D printed central section uses triply periodic minimum area structures (TPMS) to optimize heat transfer.

[0072] In addition, [Fig. 8] also illustrates another manufacturing possibility, where the external shape of the heat exchanger is not limited to a cubic design, but can be cylindrical. This cylindrical shape, applied to the 3D-printed central section, offers several advantages: it allows for better integration of the heat exchanger into industrial environments with constrained shapes, while improving fluid distribution around the structure. The cylindrical design, combined with TPMS structures, further optimizes fluid flow and increases the thermal contact area, resulting in superior thermal performance and reduced pressure losses.

[0073] The manufacture of the exchanger is done in two stages, one for the central part and the other for the external exchanger, one variant of which is a vertical tube exchanger.

[0074] For the manufacture of the 3D-printed central section: The central section of the heat exchanger, composed of complex plates and fins, is produced by 3D printing using a selective laser melting process. The main steps are as follows. • Selective laser melting (SLS): A bed of metal powder is laid out, then a laser beam selectively melts the areas defined by the 3D design, layer by layer, to form the complex structures of the heat exchanger (fins, plates, channels, etc.). This makes it possible to create geometries impossible to produce using traditional methods, such as TPMS structures. • Thermal relaxation: After printing, a thermal relaxation step is necessary to reduce the internal stresses created during laser melting. The part is placed in an oven at a controlled temperature for several hours to stabilize the material's mechanical properties. • Powder removal: Once the part has cooled, the remaining unsintered powder is removed. This step is generally done by blowing compressed air or by vibration to extract all the unfused powder, leaving the channels and heat exchange surfaces clean and functional.

[0075] For manufacturing the outer tubular section by brazing: The outer part of the heat exchanger, consisting of tubes around the 3D-printed section, is produced by a brazing process. The following are the manufacturing steps: • Flange manufacturing: A part called a "flange" is produced, featuring holes to accommodate the tubes. This flange can be laser-cut or cut using a high-pressure water jet. The holes are precisely sized to hold the tubes in position. • Tube assembly: The heat exchanger tubes (TS) are then inserted into the flange holes. The tubes can be made of different materials depending on the thermal requirements of each section of the exchanger. Copper washers are added around the tubes to facilitate the mixing process. • Vacuum brazing: The assembly consisting of the tubes, flange, and copper washers is placed in a vacuum furnace. The furnace is heated gradually using two temperature ramps: • An initial increase at a rate of 10°C / min up to 750°C to prepare the materials. • A second increase at a rate of 5°C / min up to 1100°C to perform the brazing. • Temperature maintenance: The brazing is maintained at 1100°C for approximately 15 minutes, allowing the copper washers to melt and create a solid joint between the tubes and the flange. • Controlled cooling: After brazing, the furnace is gradually cooled to 900°C under vacuum, then to ambient temperature under an argon atmosphere, in order to prevent oxidation of the materials and to guarantee good quality of the brazed joints.

[0076] Once the two parts of the heat exchanger are produced, the 3D-printed central section (1) is attached to the overall structure of the heat exchanger either by mechanical fastening using bolts, or by direct welding: • Welding: The two sections can be welded together to ensure a strong and watertight connection, particularly suitable for high-temperature applications where structural integrity is crucial. • Bolted fastening: Alternatively, the two sections can be mechanically joined using bolts, allowing for modularity and ease of maintenance, particularly in industrial environments where frequent replacements or adjustments may be necessary.

[0077] These assembly methods offer flexibility in the design and integration of the hybrid heat exchanger, ensuring performance, durability, and adaptability to diverse industrial requirements.

Claims

Demands

1. Hybrid heat exchanger comprising: • a 3D printed central section (1) optimized for high temperature heat transfer, located at the core of the exchanger; • a tubular section (2) surrounding the central section, designed for heat transfer at lower temperatures; characterized in that the 3D printed central section is integrated into the tubular section, thereby optimizing high temperature heat transfer while reducing production and operating costs.

2. Heat exchanger according to claim 1, characterized in that the 3D printed central section (1) is made up of layers of fins separated by plates, increasing the heat exchange surface.

3. Heat exchanger according to any one of the preceding claims, wherein the 3D printed central section (1) uses triply periodic minimum area structures (TPMS) to optimize heat transfer.

4. Heat exchanger according to any one of the preceding claims, wherein the tubular section (2) comprises one or more tube sections (S2.1, S2.2, S2.3) arranged around the central 3D printed section, the tubes being able to be smooth, corrugated or equipped with fins.

5. Heat exchanger according to any one of the preceding claims, wherein the 3D printed central section (1) and the tubular section (2) are arranged coaxially to ensure uniform distribution of the heat transfer fluid.

6. Heat exchanger according to any one of the preceding claims, wherein the 3D printed central section (1) is attached to the overall structure of the exchanger either by mechanical fastening using bolts or by direct welding.

7. A heat exchanger according to any one of the preceding claims, characterized in that the section produced by additive manufacturing in 3D printing comprises variable sections, in which The section of the hot fluid that is cooling down shrinks, while the section of the cold fluid that is heating up expands throughout the heat exchange process.

8. Heat exchanger according to any one of the preceding claims, wherein the 3D printed central section (1) is made from materials optimized for high temperatures, while the tubular section (2) uses materials suitable for lower temperatures.

9. Heat exchanger according to any one of the preceding claims, designed to minimize heat losses by convection and radiation, thanks to the central placement of the 3D printed section surrounded by the tubes.

10. A method for manufacturing a hybrid heat exchanger according to any one of the preceding claims, comprising the following steps#: • manufacturing the 3D printed central section (1) by selective laser melting#; • thermal relaxation of the printed part#; • emptying of the residual unsintered powder#; • manufacturing the tubular section (2) by assembling tubes on a flange#; • vacuum brazing of the tubes on the flange#; • assembly of the 3D printed central section (1) and the tubular section (2) by welding or mechanical fastening.

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