Heat exchanger with multiple thermal groups
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2026-01-14
- Publication Date
- 2026-08-13
Smart Images
Figure IB2026050288_13082026_PF_FP_ABST
Abstract
Description
Multi-thermal group heat exchanger TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to a heat exchanger comprising a plurality of thermal groups each comprising a plurality of fluid transport channels in the form of helicals of linear length LL arranged in a single cylindrical monobloc body made by additive manufacturing, the single cylindrical body being of height H and of reference axis AL-AL. STATE OF PRIOR ART
[0002] Heat exchangers are particularly common devices used in countless applications and systems, especially those involving internal combustion engines and refrigeration units. Typically, heat exchangers consist of a long tube through which a fluid circulates. The tube often forms a circuit in which the flow alternates back and forth, arranged side by side. When two or more fluids are used, the exchangers are typically serpentine in shape, with a double winding that allows adjacent tubes to be in thermal contact, thus facilitating heat exchange. These arrangements are generally quite bulky, with complex architectures, and their efficiency could be improved. To enhance these devices, several attempts have been made with arrangements that aim to move away from the use of long, serpentine tubes.
[0003] For example, document US20090101321 describes a heat exchanger comprising a main body into which a plurality of cells are inserted, aligned side by side. This type of device is advantageously compact and efficient, but complex to manufacture. However, the straight paths of the cells limit the heat exchange lengths.
[0004] Document WO2016074048 describes a heat exchanger consisting of multiple superimposed plates in which fluid circulation channels are arranged. This architecture allows the exchanger to be adapted to specific requirements. However, this type of construction with multiple component parts is relatively complex and expensive. Wall-Echang-LL
[0005] Both of these types of architectures are complex to implement, costly, and have performance levels that could be improved.
[0006] The US10094621 document relates to a spiral heat exchanger with opposed flow, constructed using two rectangular tunnels made of metal sheets separated from each other by a spacer to avoid contact between the tunnels, and wound to form a spiral.
[0007] Document US2015 / 300745 relates to a spiral heat exchanger comprising a central core around which are wound two helices housed in a tube forming an internal wall.
[0008] These last two exchangers are complex to manufacture and assemble (particularly because they require the assembly of several elements together, for example sheets by welding or brazing), provide limited efficiency, and due to the windings, are difficult to implement and involve large dimensions.
[0009] US patent 2021270535 describes a device for use in the production of a tube bundle for a wound heat exchanger, in which tubes are wound in multiple layers around a central tube extending in an axial direction, with ribs extending in the axial direction being arranged between the tube layers. The invention further relates to a method for manufacturing a tube bundle using said device.
[0010] The US2021199390 document describes a method for controlling the recovery of heat energy from a wastewater flow in a spiral pipe to a heat transfer fluid circulating in a first heat transfer space inside a container with a temperature difference between the wastewater and the heat transfer fluid.
[0011] The US2018187980 document describes a water heat recovery device with first and second passes arranged in a counter-current orientation. It has a hot side and a cold side for fresh water supplied under pressure. It extracts heat from a building's water pipes. Wall-Echang-LL
[0012] These last three documents all concern "conventional" heat exchangers, that is, those using multiple separate tubes to carry the different fluids, these tubes being housed within a casing. These multi-component designs are complex, expensive, exhibit significant efficiency losses, and require large dimensions.
[0013] FR3088995 describes a coil for a heat exchanger, comprising at least a first turn and a second turn, the first and second turns being adjacent, each turn having, in a cross-sectional plane in the direction of flow of a fluid in the coil, a wall delimiting a section for the passage of the fluid in the turn, the passage section having a shape comprising a major axis and a minor axis, an orthogonal projection of an end of the major axis of the first turn onto a line comprising the major axis of the second turn belonging to the major axis of the second turn, the first and second turns having a portion of wall in common.
[0014] US11841194 describes a device intended for use in the production of a tube bundle of a wound heat exchanger, in which the tubes are wound in a plurality of tube layers on a central tube oriented in an axial direction.
[0015] We are also familiar with document FR220091. This document describes a cylindrical, multi-channel, single-piece heat exchanger whose channels are spirally wound around a central axis. All the channels share the same axis. Due to the cylindrical configuration of the exchanger, with all channels wound at the same pitch, the further one moves from the central axis, the longer the channels must travel to cover the entire length of the exchanger. Thus, the linear length of the channels increases with their radial position. This arrangement results in discontinuities in the heat exchange characteristics depending on the channel positions. The overall characteristics of the exchanger are therefore particularly difficult to control.
[0016] To overcome the various disadvantages mentioned above, the invention provides for different technical means. DESCRIPTION OF THE INVENTION
[0017] Firstly, a primary objective of the invention is to provide a heat exchanger with improved efficiency. Wall-Echang-LL
[0018] Another objective of the invention is to provide a heat exchanger having uniform thermal and fluidic characteristics.
[0019] Another objective of the invention is to provide a heat exchanger with an optimal exchange surface.
[0020] Another objective of the invention is to provide a compact, robust and durable heat exchanger.
[0021] To achieve this, the invention provides for a heat exchanger comprising at least two thermal groups GTi, each transporting a thermal fluid FTi, and of which at least one thermal group GTi comprises a plurality of fluid transport channels in the form of helicals of linear length LL arranged in a single monobloc body, the single body being of height H, with reference axis AL-AL, said thermal groups GTi being made up of a plurality of coaxial cylindrical stacks of stroke channels Ci wound in a spiral around the reference axis AL-AL, each stack being spaced from the axis AL-AL by a radius Ri, all the channels of all the thermal groups GTi of the same thermal fluid FTi having a substantially identical linear length LL.
[0022] This architecture allows for the design of a heat exchanger with channels of identical linear lengths for at least one of the heat transfer fluids. This enables precise control of the heat transfer characteristics and ensures uniformity across the entire volume of the exchanger. This architecture results in uniform heat transfer rates for all the thermal units. The arrangement also prevents variations in pressure drop between the different thermal units.
[0023] According to an advantageous embodiment, the channels of the same GTi thermal group have a substantially identical cross-section.
[0024] In another advantageous embodiment, the channels of two adjacent thermal groups have identical cross-sections. This particular case allows, for example, the use of identical fluids in different thermal groups. Wall-Echang-LL
[0025] According to an advantageous embodiment, the stroke Ci of the channels of a given stack is a function of the ratio H / LL and Ri.
[0026] According to another advantageous embodiment, the stroke Ci of the channels in a given stack corresponds to: where H corresponds to the height of body 2, Ri corresponds to the radius of thermal group GTi, and LL is the linear length of the channels of thermal group GTi.
[0027] According to yet another advantageous embodiment, the exchanger includes at least one connector serving as a single entry or exit point for all the channels of thermal groups using the same fluid.
[0028] Advantageously, the connectors are arranged at the end of the single body.
[0029] Such an arrangement facilitates connections between the exchanger and the rest of the fluidic circuit.
[0030] Another advantage is that the single unit is metallic and manufactured using additive manufacturing. Metals such as copper, steel, aluminum, titanium, or an alloy based on one or more of these elements are used. These metals and alloys allow for the production of highly efficient heat exchangers. DESCRIPTION OF THE FIGURES
[0031] All implementation details are given in the following description, supplemented by figures 1 to 12, presented solely as non-limiting examples, and in which: -Figure 1 is a perspective cross-section of an example of a heat exchanger body, illustrating an example of fluid passage paths with six thermal groups; -Figure 2 is a schematic representation partially illustrating the arrangements of several thermal groups, seen in perspective; Wall-Echang-LL-la figure 3 is a schematic representation partially illustrating the arrangements of the thermal groups of figure 2, in side view; -Figure 4 shows the arrangement of figures 2 and 3 with the central thermal group illustrated in its entirety; -Figure 5 shows the arrangement of figures 2 and 3 with the two central thermal groups illustrated in full; -Figure 6 shows the arrangement of figures 2 and 3 with all the thermal groups illustrated in full; -Figure 7 shows the arrangement of Figure 6, in front view; -Figure 8 is a schematic representation illustrating the sections of the thermal groups and their path helices; -Figure 9 shows a perspective view of an example of an exchanger with a body and a plurality of connectors arranged at the ends of the body; -Figure 10 is a schematic representation illustrating an example of paired thermal group channels grouping towards a common connector; -Figure 11 is a schematic representation illustrating an example of paired thermal group channels grouping towards a common connector; -Figure 12 is a schematic representation illustrating an example of paired thermal group channels grouping towards a common connector. DETAILED DESCRIPTION OF THE INVENTION DEFINITIONS
[0032] The term "fluid" refers to a substance (pure or mixture) capable of transporting thermal energy through a channel designed for this purpose. A fluid can be in a liquid or gaseous state. Commonly used fluids include water, air, helium, nitrogen, hydrogen, etc.
[0033] By "separate fluids" we mean fluids circulating in distant thermal groups, without fluidic communication between them. The fluids may be different or identical.
[0034] The term "monobloc body" refers to a single part produced by additive manufacturing, preferably metallic, implemented by melting additive material such as powder or wire or other support, and whose disassembly is impossible without compromising the integrity of the part. Wall-Echang-LL
[0035] By "substantially identical linear length" we mean channels where the difference in length between the shortest and the longest is less than 5%, and preferably less than 3%, and even more preferably less than 1%.
[0036] By "channels of substantially identical cross-section" we mean channels in which the difference in cross-section between the narrowest and the widest is less than 5%, and preferably less than 3% and even more preferably less than 1%.
[0037] Figure 1 illustrates an example of a unit or monobloc body 2 of height H and reference or longitudinal axis AL-AL, constituting the core of the heat exchanger 1 shown in its entirety in the example of Figure 9. In this example, the body 2 is cylindrical and the reference axis AL-AL is also the central axis of the body. The fluidic channels 3 are arranged to allow heat exchange between the fluids. To promote heat exchange, the body 2 is made of a material with high thermal conductivity, preferably metallic, such as aluminum, copper, steel, or a similar material. As illustrated, the body comprises a plurality of thermal groups GTi, in this example numbered from GT1 to GT6. Thermal group GT1 is the most central, with the smallest radius Ri, while thermal group GT6, with the largest radius Ri, occupies the outermost radial position.Each thermal group comprises a plurality of helical fluid transport channels 3 of linear length LL. Within a given thermal group, the channels are arranged in a stack 4, with the multiple stacks 4 of the thermal groups being coaxial. To standardize heat transfer characteristics and avoid variations in pressure drop, all channels 3 of the same thermal group GTi have a substantially identical, and preferably identical, linear length LL. For the same reasons, the channels of the multiple thermal groups of a body 2, in this example from GT1 to GT6, have a substantially identical, and preferably identical, linear length LL. As more clearly seen in Figures 2 to 6, the identical linear lengths are achieved through an architecture in which the pitch varies from one group to another, the pitch value increasing from the center outwards, i.e., in this example, from GT1 to GT6.
[0038] Furthermore, also to optimize the same characteristics, the channels of the same GTi thermal unit preferably have a substantially identical cross-section, and more preferably identical. According to a first embodiment, the channels of the Wall-Echang-LL multiple thermal groups GT1 to GT6 have a substantially identical and preferably identical cross-section.
[0039] The following relationship allows us to determine the step (or stroke) value of a given thermal group: where H corresponds to the height of body 2, Ri corresponds to the radius of thermal group GTi, and LL is the linear length of the channels of thermal group GTi.
[0040] We observe that the stroke is proportional to the radius Ri of the relevant GTi thermal group. More specifically, the stroke Ci of the channels in a given 4-channel stack is a function of the H / LL ratio and Ri.
[0041] However, as shown in Figure 8, and as seen in the examples in Figures 1 to 6, the cross-sectional area can differ between thermal groups. This is the case, for example, when the heat exchanger is used with two or more different thermal fluids (FTi). Since each fluid has its own characteristics, it may be desirable to provide cross-sectional areas adapted to each type of fluid. Consequently, the spacing between neighboring channels of different thermal groups can also vary. Furthermore, the larger the cross-sectional area of a channel, the more space it occupies, which can limit the number of channels in a single stack (4) or shift the Ri of the directly adjacent thermal group (GTi).
[0042] The following relationship takes these additional parameters into account: Ci = Ne . (He + H ) , where Hc unit height (in the direction of the AL-AL axis) of the channels of the same GTi. Hi unit height (in the direction of the AL-AL axis) inter-channel between two channels of the same GTi. The number of channels of the same GTi. Wall-Echang-LL
[0043] We thus obtain a system of two equations and six unknowns, composed of the relation Ci as a function of the ratio H / LL and Ri, and Ci as a function of Ne, Hc, and Hi. To solve it, we need to fix the unknowns to solve the system. • Ri depends on the GTi in question and is a function of the channel width of the same Fti and the wall thickness. • H is fixed, defined by the permissible height according to the constraints of additive manufacturing. • Hc has a maximum value that must not be exceeded for mechanical dimensioning considerations • Hi has a minimum value that must not be exceeded for mechanical dimensioning considerations
[0044] Thus the two remaining unknowns are LL and Ne, the objective is to solve the system of equations for each GTi by maximizing the number Ne of channels that can be accommodated in a space Ci while respecting Hcmax and Himax.
[0045] As shown in Figures 1 and 3, and more specifically in Figure 7, the stroke Ci of the channels is determined from their central axis, this central axis running along the height H of the body 2, between the two faces of the body. Therefore, since the channels have a non-zero cross-section, they are interrupted at mid-height, i.e., at the level of their central axis, at both ends of the body 2. For example, Figure 7 clearly shows the channels 3 of the GT6 thermal unit, which are interrupted at mid-height.
[0046] Figure 2 is a schematic perspective view of an example of channel routing for several thermal groups. The unit body 2, or monoblock, in which these channels are formed is not shown in this figure. It is essentially a "negative" view showing the voids or areas where there is no material. Each of the fluid channels 3, which form a helical winding, is observed. As illustrated, the winding is made around a longitudinal axis AL of the heat exchanger, which serves as the reference axis. Figure 3 illustrates the same channels and thermal groups as Figure 2, but from a front view. In both figures, two of the channels 3 of the central thermal group GT1 are shown, one of which is shaded to facilitate visualization of the two channels.To simplify the figure and allow for a clear view of the winding variations, and in particular the pitch variations, as a function of the evolution of the radius, only one channel is illustrated for the following thermal groups. Wall-Echang-LL
[0047] Figures 4, 5, and 6 illustrate the progressive stacking of the various thermal groups. Figure 4 shows the central thermal group with all its channels. Figure 5 shows the first two thermal groups from the center in their entirety. Figure 6 shows all the thermal groups with all their channels. To complement these schematic views, Figure 7 shows a front view of body 2 from Figure 6.
[0048] As shown in Figure 1, the number of channels in a body 2 can be relatively high. For example, in a body with a height H of 100 mm and a diameter of 180 mm, GTi thermal units with the following characteristics can be integrated:
[0049] To avoid having to connect each of the channels individually to the rest of the fluid circuit to which the exchanger is connected, 5 connectors are provided.
[0050] Figure 9 illustrates an example of a two-fluid heat exchanger with two connectors 5 on each side, i.e., an inlet connector 5 and an outlet connector 5, each on its respective side of the exchanger. The cross-sectional view shows the two axial inlets / outlets 7 of the thermal fluid FT1 and the two lateral inlets / outlets 8 of the thermal fluid FT2.
[0051] Figures 10 to 12 are schematic representations in "negative" mode of an example of connector 5 intended to make a fluidic link between the channels of the same thermal fluid FTi and thus minimize the number of inlets / outlets of the exchanger.
[0052] In this example, the thermal fluid FT 1 is composed of the odd GTi GT 1, GT3 and GT5 and the thermal fluid FT2 is composed of the even GTi GT2, GT4 and GT6. Wall-Echang-LL
[0053] The junction zones 6 are observed where the channels of the thermal groups of the same thermal fluid FTi join to form a single inlet / outlet. Figure 10 illustrates a heat exchanger 1 with two thermal fluids: thermal fluid FT1 with an axial inlet / outlet 7 in the center, and thermal fluid FT2 with a lateral inlet / outlet 8. In this example, the connectors 6 of these two thermal fluids fit together in complementary star-shaped radial arrangements, allowing all the thermal groups carrying the same thermal fluid to be linked together.
[0054] Because this architecture is particularly complex, especially for heat exchangers using small-section channels, it is advantageous to manufacture such a heat exchanger using a material addition process, such as a 3D printer. This allows for the easy implementation of virtually any arrangement with multiple helical passages and connectors at the channel ends.
[0055] Manufacturing trials conducted with this heat exchanger architecture, produced using metal additive manufacturing, have achieved channel dimensions of 0.4 mm wide by 1 mm high, and even more preferably down to 0.2 mm wide by 0.5 mm high. The achieved heat exchange wall thicknesses are 0.2 mm, and even more preferably 0.1 mm. With current manufacturing technologies, no other manufacturing method can achieve such dimensions.
[0056] These dimensional characteristics allow for excellent heat transfer coefficients, while ensuring easy depowder removal (in the case of metal additive manufacturing by powder bed fusion) and thus the operability of the constructed model. This also allows for heat exchange area compactness of 3500 m² / m³, and more preferably 5000 m² / m³. The architecture with multiple thermal units allows for the creation of heat exchangers with well-controlled thermal characteristics. To optimize thermal efficiency, it is beneficial to arrange as many channels as possible within each thermal unit. Wall-Echang-LL Reference numbers used in the figures Heat exchanger One-piece single body Canals Coaxial cylindrical stacks Connector Junction zone FTi axial thermal fluid inlet / outlet FTi thermal fluid side inlet / outlet Wall-Echang-LL
Claims
DEMANDS 1. Heat exchanger (1) comprising at least two thermal groups GTi each transporting a thermal fluid FTi and of which at least one thermal group GTi has a plurality of fluid transport channels (3) in the form of helicals of linear length LL arranged in a single monobloc body (2), the single body (2) being of height H, with reference axis AL-AL, said thermal groups GTi being made up of a plurality of coaxial cylindrical stacks (4) of channels (3) of stroke Ci wound in a spiral around the reference axis AL-AL, each stack (4) being spaced from the axis AL-AL by a radius Ri, characterized in that all the channels (3) of all the thermal groups GTi of the same thermal fluid FTi have a substantially identical linear length LL.
2. Heat exchanger (1) according to claim 1, in which the channels of the same thermal group GTI have a substantially identical cross-section.
3. Heat exchanger (1) according to any one of claims 1 or 2, in which the channels of two adjacent thermal groups have identical cross-sections.
4. Heat exchanger (1) according to any one of claims 1 to 3, wherein the stroke Ci of the channels of a given stack is a function of the ratio H / LL and Ri.
5. Heat exchanger (1) according to claim 4, in which the stroke Ci of the channels of a given stack corresponds to: where H corresponds to the height of body 2, Ri corresponds to the radius of thermal group GTi, and LL is the linear length of the channels of thermal group GTi.
6. Heat exchanger (1) according to any one of claims 1 to 5, wherein the exchanger comprises at least one connector (5), serving as a single inlet or outlet point for all the channels of thermal groups using the same fluid.
7. Heat exchanger (1) according to claim 6, in which the connectors (5) are arranged at the end of the single body (2). Wall-Echang-LL8. Heat exchanger according to any one of the preceding claims, wherein the single body (1) is metallic and produced by additive manufacturing.
9. Heat exchanger according to claim 8, wherein the body is made of copper, or steel, or aluminum, or titanium or an alloy based on one or more of these elements. Wall-Echang-LL