WO2024132477A1

WO2024132477A1 - Plate heat exchanger module with plate channels, which channels in one circuit include at least one fluid supply and distribution zone formed by studs, and which channels in the other circuit are delimited by the flat plate surface and thickened edges

Info

Publication number: WO2024132477A1
Application number: PCT/EP2023/084150
Authority: WO
Inventors: Xavier JEANNINGROS; Lionel Cachon; Emmanuel Rigal; Sébastien Vincent
Original assignee: Commissariat A L'energie Atomique Et Aux Energies Alternatives
Priority date: 2022-12-20
Filing date: 2023-12-04
Publication date: 2024-06-27
Also published as: FR3143725A1

Abstract

The invention essentially consists in producing a plate heat exchanger module whose plates are stacked or produced by additive manufacturing, wherein at least one of the pre-headers of one of the fluid circuits, referred to as the first circuit, is produced using studs distributed over the plate surface, which studs delimit the channels in which the fluid circulates before reaching its heat exchange zone, and the other of the fluid circuits, referred to as the second circuit, is delimited solely by the flat surface of a plate and the discontinuous lateral and longitudinal edges which have a greater thickness than the flat surface.

Description

Title: Channel plate heat exchanger module of which those of one circuit integrate at least one fluid supply and distribution zone formed by pads and those of the other circuit are delimited by the flat plate surface and extra thickness edges.

Technical area

The present invention relates to a heat exchanger module with a stack of metal plates, integrating at least two fluid circuits.

The invention relates more particularly to the production of a new type of heat exchanger module to reduce pressure losses without harming the uniformity of the distribution of the different internal fluid circulation channels, and while ensuring both good thermal efficiency and satisfactory thermomechanical loading.

Known heat exchangers comprise either a single or at least two circuits with internal fluid circulation channels. In single-circuit exchangers, heat exchanges take place between the circuit and a surrounding fluid in which it is bathed. In exchangers with at least two fluid circuits, heat exchanges take place between the two fluid circuits.

Chemical reactors are known which implement a continuous process according to which a small quantity of co-reactants is simultaneously injected at the inlet of a first fluid circuit, preferably equipped with a mixer, and we recover the chemical product obtained at the outlet of said first circuit. Among these known chemical reactors, some include a second fluid circuit, usually called utility, and whose function is to thermally control the chemical reaction, either by providing the heat necessary for the reaction, or on the contrary by evacuating the heat released by the reaction. -this. Such chemical reactors with two fluid circuits with utility are usually called exchanger-reactors.

The present invention concerns both the production of heat exchanger modules with a sole thermal exchange function and integrating two fluid circuits as well as the production of exchangers-reactors. Also, by “heat exchanger module with at least two fluid circuits”, it is necessary to understand in the context of the invention, both a heat exchanger module with a function only of thermal exchanges and an exchanger -reactor. The main use of an exchanger module between two fluids according to the invention is its use with water as one of the two fluids. H can advantageously be an exchange between liquid water and liquid water.

The main application targeted by an exchanger module according to the invention is the exchange of heat between liquid water of a primary circuit, and a secondary circuit of a pressurized water nuclear reactor (PWR) of small or medium power type or SMR in English (acronym for “Small Modular Reactor”), with heat-generating vocation.

By “heat-producing”, we mean here and in the context of the invention, a nuclear reactor whose power is mainly dedicated to the supply of heat. The power of a heat-producing reactor can be 100% to provide heat. A small part of its power can still be used to provide electricity.

A heat exchanger module according to the invention can also be implemented in any other application requiring an exchange between two fluids, such as a liquid and a gas, preferably when it is necessary to have a compact exchanger. and high thermal power.

By “primary fluid”, we mean in the context of the invention, the usual meaning in thermal, namely the hot fluid which transfers its heat to the secondary fluid which is the cold fluid.

Conversely, by “secondary fluid” is meant in the context of the invention, the usual meaning in thermal, namely the cold fluid to which the heat of the primary fluid is transferred.

In the main application, the primary fluid is the liquid water of the primary circuit of a PWR reactor, while the secondary fluid is the liquid water of the secondary circuit of said PWR reactor.

Prior art

Known tube exchangers are for example tube and shell exchangers, in which a bundle of straight or curved tubes in the shape of a U or in the shape of a helix is fixed on pierced plates and arranged inside an enclosure waterproof called grille. In these tube and shell exchangers, one of the fluids circulates inside the tubes while the other fluid circulates inside the shell. These tube and shell exchangers have a large volume and are therefore of low compactness. Existing so-called plate heat exchangers have significant advantages over existing so-called tube heat exchangers, in particular their thermal performance and their compactness thanks to a ratio of the surface area to the volume of heat exchange favorably pupil. Compact plate exchangers are used in many industrial fields. In this field of compact plate exchangers, numerous elementary shapes defining heat exchange patterns have been developed.

We can first mention plate exchangers incorporating fins, in which a heat exchange pattern is defined by a structure delimited by fins, the structures being attached between two metal plates and can have very varied geometries. The exchange reason may be different between one of the two fluid circuits of the exchanger and the other. The assembly between metal plates is usually done by brazing, or by diffusion welding.

Corrugated or corrugated plate exchangers are also known. The undulations are created by stamping a plate separating the two fluid circuits. As a result, the exchange pattern is identical for each of the two fluid circuits.

The flow of fluids generated by this type of exchange pattern is three-dimensional and, therefore, very efficient. The assembly between plates is done either by bolted connection or by their peripheral welding (conventional welding, or by diffusion welding).

Finally, plate exchangers with machined grooves are known, the machining being mechanical or carried out electrochemically. The channels defined by the machining are of millimeter section and are most often continuous and according to a regular zigzag profile. The plates are assembled by diffusion welding, in particular by hot isostatic compression (CIC) allowing welding on all contact points between two adjacent plates. This type of machined groove plate exchanger is therefore intrinsically very resistant to pressure.

The patent application entitled “Nuclear installation comprising at least one modular nuclear reactor (SMR) and a vessel well delimiting a water basin in which the SMR reactor block and the exchangers between primary and secondary circuits are immersed.” and filed on the same day as this application proposes a new nuclear reactor architecture. In this architecture, the heat exchangers between the primary and secondary circuits of a heat-producing PWR reactor are arranged on the periphery of the reactor vessel, these components being immersed in a basin of water as the secondary circuit fluid. The circulation of water in the primary and secondary circuits is carried out by natural convection, without a pump. The circulation of the primary fluid is obtained by thermosyphon and that of the secondary fluid is obtained by creating a thermocline within the water basin.

The inventors of the present application had to design the exchangers between primary and secondary circuits according to this architecture.

Firstly, they analyzed that circulation by natural convection of water in the primary and secondary circuits has the disadvantage of being relatively sensitive to pressure losses.

However, the specifications for a submerged exchanger as indicated above impose a maximum pressure loss of 2000 Pa for the part of the secondary circuit within the exchanger.

The inventors considered that plate exchangers assembled by hot isostatic compression (CIC) presented various advantages as exchangers between primary and secondary circuits of the aforementioned reactor, in particular due to the fact that compared to tube and shell exchangers, they are often more compact and less sensitive to vibrations.

More particularly, they analyzed that an exchanger module as disclosed in patent application EP4086556A1 was a good candidate for application as an exchanger between primary and secondary circuits of the aforementioned reactor. Indeed, the module according to this patent application has the following major advantages:

- possibility of manufacturing by a CIC process;

- control of flow distribution, with imposed pressure loss;

- guarantee of mechanical strength;

- minimization of thermal inertia, for thermomechanical sizing during transient operating regimes of the reactor;

- minimization of the number of intake manifolds. The inventors then carried out calculations of the pressure losses of a module according to this patent application EP4086556A1, from a digital simulation tool for digital fluid mechanics (MFN), (in English “Computational Fluid Dynamics” from acronym CFD), under the operating conditions of a heat-generating reactor mentioned above.

The following table 1 summarizes these operating conditions for thermal power exchanged by a module of 4.167 MW.

[Table 1]

The calculations carried out indicate that the pressure loss obtained in the secondary circuit is 2455 Pa, including 1055 Pa in the zone of grooved exchange channels and 1400 Pa in the inlet and outlet precollectors.

The maximum pressure loss of 2000 Pa imposed by the specifications is therefore largely exceeded.

There is therefore a need to further improve plate exchanger modules such as that according to patent application EP4086556A1, in particular in order to reduce pressure losses within the modules, and more particularly their secondary circuit.

The aim of the invention is to meet this need. Presentation of the invention

To do this, the invention relates to a heat exchanger module with at least two fluid circuits, of longitudinal axis comprising a stack of plates defining at least two fluid circuits, at least a part of the plates comprising each of the channels of fluid circulation, in which:

- the channels of one of the two circuits, called the first circuit, present:

• at least one zone for supplying and distributing the fluid, called the first fluid, from outside the stack, forming a pre-collector of the first fluid, in which the channels are delimited, for each plate, by studs solids distributed over the plate surface and open out at one of the longitudinal ends of the plate,

• an exchange zone continuous with the pre-collector in which the channels are delimited, for each plate, each by a groove separated from each other by a rib and extend along the longitudinal axis;

- the channels of the other of the two circuits called the second circuit present:

• at least one zone for supplying and distributing the fluid, called the second fluid, from outside the stack, forming a pre-collector for the second fluid, in which the single channel is delimited, for each plate, by the flat central surface of the plate, a lateral edge with excess thickness relative to the flat surface of the plate and the two discontinuous longitudinal edges with the same excess thickness relative to the flat surface of the plate as the lateral edge,

• a continuous exchange zone with the pre-collector in which the single channel is delimited, for each plate, by the flat central surface of the plate and the two discontinuous longitudinal edges with the same thickness relative to the flat surface of the plate that the lateral edge, the distance between the lateral edge and one of the discontinuous longitudinal edges in excess thickness defining an entry or exit opening for the second fluid in the stack.

According to an advantageous embodiment, the module comprises two pre-collectors of the first circuit, each arranged at one of the longitudinal ends of the stack, one of the two pre-collectors forming a fluid inlet pre-collector , the other forming a fluid outlet precollector.

The pads of the first circuit are advantageously full. According to an advantageous embodiment, the module comprises at least at one of the longitudinal ends of the stack, a fluid collector opening onto a lateral base of the stack onto which the channels of the pre-collector of the first circuit open but not those of the pre-collector of the second circuit.

According to this mode, the module advantageously comprises at one of the longitudinal ends, a fluid collector forming the inlet collector of the first circuit and at the other of the longitudinal ends, a fluid collector forming the outlet collector of the first circuit .

According to another advantageous embodiment, the module comprises on a lateral side of the stack, a fluid collector crossing the stack transversely to the axis (X) and opening onto the channels of the pre-collector of the second circuit but not on those of the first circuit.

According to this mode, the module advantageously comprises on each lateral side of the stack, a fluid collector forming the output collector of the second circuit.

According to an alternative configuration, the pads are uniformly distributed staggered on the plate surface of the pre-collector, in a triangular pattern.

According to another alternative, the pads are uniformly distributed on the plate surface of the pre-collector in a rectangular or square pattern.

More preferably, the pads are of generally cylindrical shape.

More preferably, the channels of the exchange zone of the first circuit are straight, parallel to each other and extend parallel to the longitudinal axis (X).

The invention also relates, according to a first alternative, to a method of manufacturing an exchanger module which has just been described, comprising the following steps: al/ producing a plurality of at least two metal plates each including:

- on one of the two main faces:

• at least one supply and distribution zone of the first fluid, called the first fluid, forming a pre-collector of the first fluid, in which the channels are delimited by solid pads distributed over the plate surface and open to one longitudinal ends of the plate, • an exchange zone continuous with the pre-collector in which the channels are each delimited by a groove separated from each other by a rib;

- on the other of the two main faces:

• at least one supply and distribution zone of the second fluid called second fluid, forming a pre-collector of the second fluid, in which the single channel is delimited by the flat central surface of the plate, a lateral edge in excess thickness relative to to the flat surface of the plate and the two discontinuous longitudinal edges with the same excess thickness relative to the flat surface of the plate as the lateral edge,

• a continuous exchange zone with the pre-collector in which the single channel is delimited by the flat central surface of the plate and the two discontinuous longitudinal edges with the same excess thickness relative to the flat surface of the plate as the lateral edge, the distance between the lateral edge and one of the discontinuous longitudinal edges in excess thickness defining an inlet or outlet opening for the second fluid; b 1/ mirroring with alignment and contact by their main faces of two plates comprising the studs and ribs; cl/ assembly by hot isostatic compression (CIC) of the two plates, so as to obtain a metal sheet; d 1/ stacking of the plurality of layers assembled by CIC according to step c/ with installation of an end plate at each longitudinal end of the stack; el/ welding, preferably by laser, of the plurality of layers and end plates stacked so as to obtain the module.

The invention also relates, according to a second alternative, to a method of manufacturing an exchanger module which has just been described, comprising the following steps: a2Z production of a plurality of at least two metal plates comprising each:

- on one of the two main faces:

• at least one supply and distribution zone of the first fluid, called the first fluid, forming a pre-collector of the first fluid, in which the channels are delimited by solid pads distributed over the plate surface and open to one longitudinal ends of the plate,

• an exchange zone continuous with the pre-collector in which the channels are each delimited by a groove separated from each other by a rib; on the other of the two main faces:

• at least one supply and distribution zone of the second fluid called the second fluid, forming a pre-collector of the second fluid, in which the single channel is delimited by the flat central surface of the plate,

• a continuous exchange zone with the pre-collector in which the single channel is delimited by the flat central surface of the plate and the two discontinuous longitudinal edges with the same excess thickness relative to the flat surface of the plate as the lateral edge, the distance between the lateral edge and one of the discontinuous longitudinal edges in excess thickness defining an inlet or outlet opening for the second fluid; b2/ mirroring with alignment and contact by their main faces of two plates comprising the studs and ribs; c2/ assembly by hot isostatic compression (CIC) of the two plates, so as to obtain a metal sheet; d2/ alternating stacking of the plurality of layers assembled by CIC according to step c/ with at each lateral end, the teeth of a metal comb defining a lateral edge in excess relative to the flat surface of the plate and with each longitudinal end , the teeth of a metal comb defining the two discontinuous longitudinal edges with the same excess thickness relative to the flat surface of the plate as the lateral edge; e/ assembly by hot uniaxial compression (CUC), of the plurality of layers, combs and end plates stacked so as to obtain the module.

We can also consider producing an exchanger module by additive manufacturing.

The invention also relates to the use of the heat exchanger as described above, the fluid of the first circuit, as primary fluid, being liquid water and the fluid of the second circuit, as secondary fluid, being also liquid water.

The fluid from the first or second circuit can come from a nuclear reactor.

The invention also relates to a nuclear installation comprising a pressurized water nuclear reactor, in particular of the SMR type and comprising a plurality of exchanger modules such as that described above Thus, the invention essentially consists of producing an exchanger module with stacked plates or produced by additive manufacturing, of which at least one of the pre-collectors of one of the fluid circuits, called the first circuit, is produced with pads distributed over the plate surface which delimits the channels in which the fluid circulates before reaching its heat exchange zone and the other of the fluid circuits, said second circuit is delimited only by the flat surface of a plate and the lateral edges and discontinuous longitudinal sections in excess of the flat surface.

The pads of the first circuit and the extra-thickness edges of the second circuit guarantee the pressure resistance of the plates while having low thermal inertia.

The pads make it possible to guarantee homogeneous distribution of the fluid by minimizing the addition of pressure losses, independently of the geometry of the channels in the heat exchange zone.

The geometric shapes and distributions of the pads can be modified as desired to control the distribution of the fluid depending on the intended application and its constraints, particularly temperature and pressure.

We can also vary the density of pads in the pre-collector.

Thanks to the pads according to the invention in place of the bifurcations according to patent FR3054879B 1, we also get rid of the zones of thermal inertia Z.I as illustrated in Figure IB.

In addition, the pads make it possible to define the geometries of exchanger modules with an inlet and outlet of fluid on the same longitudinal face of the module to obtain a side-by-side arrangement of modules and minimize the lengths of piping between them.

The absence of pads and isthmuses (ribs separating grooves forming channels) in the secondary circuit makes it possible to significantly reduce the pressure losses of the second circuit. This makes the exchanger module compatible with an application such as a heat-generating PWR nuclear reactor, for which the module is immersed in the fluid of its secondary circuit.

In addition, the fact of arranging the input and output collectors at the longitudinal ends of the stack of the module makes it possible to reduce the pressure losses of the first circuit. All applications requiring heat exchangers or steam generators can be considered with exchanger modules according to the invention, among which we can cite all types of nuclear reactors GEN 3, GEN 4, SMR (English acronym for “Small Medium Reactor), urban heating networks, EHT electrolysers, the oil and gas industry, the solar industry, the chemical industry...

Other advantages and characteristics will become clearer on reading the detailed description, given for illustrative and non-limiting purposes, with reference to the following figures.

Brief description of the drawings

[Fig 1] Figure 1 is a perspective and partial cutaway view of an exchanger module according to the invention with its collectors, Figure 1 showing a main face of a plate whose channels and pads are dedicated to the circulation of liquid water as the primary fluid.

[Fig 2] Figure 2 is a front view showing one of the main faces of a plate whose channels and pads are dedicated to the circulation of liquid water as a primary fluid.

[Fig 3] Figure 3 is a front view showing the other of the main faces of the plate according to Figure 2, the flat surface of which is dedicated to the circulation of liquid water as a secondary fluid.

[Fig 4A] [Fig 4B] Figures 4A, 4B are perspective views showing steps of a first method of manufacturing an exchanger module according to the invention.

[Fig 5] Figure 5 is a perspective view of an exchanger module according to the invention manufactured according to a second manufacturing process.

[Fig 6] Figure 6 is a perspective view of a longitudinal comb implemented on one of the longitudinal edges of an exchanger module during its manufacture according to the second process.

[Fig 7] Figure 7 is a partial perspective view showing the implementation of the longitudinal comb according to Figure 6 within a stack in order to form an exchanger module according to the invention.

[Fig 8] Figure 8 is a perspective view of a side comb implemented on one of the longitudinal edges of an exchanger module during its manufacture according to the second process. [Fig 9] Figure 9 is a partial perspective view showing the implementation of the side comb according to Figure 8 within a stack in order to form an exchanger module according to the invention.

[Fig 10] Figure 10 is a perspective and partial cutaway view of an exchanger module according to the invention without its collectors, Figure 10 illustrating the circulation of the primary fluid within the module.

[Fig 11] Figure 11 is a perspective and partial cutaway view of an exchanger module according to the invention without its collectors, Figure 11 illustrating the circulation of the secondary fluid within the module.

detailed description

For the sake of clarity, the same elements are designated by the same numerical references according to the state of the art and according to the invention.

It is specified that throughout the request, the terms “inlet”, “outlet”, “upstream”, “downstream” are to be understood in relation to the direction of circulation of the fluid considered within a module. heat exchange according to the invention.

The exchanger module M is described as an exchanger module between liquid water as a primary circuit fluid (Fl) and also liquid water as a secondary circuit fluid (F2) of an SMR type PWR nuclear reactor.

In Figure 1, there is therefore shown a heat exchanger module M according to the invention with two fluid circuits, which is implemented by way of example for an exchange between liquid water (Fl), in as primary fluid and liquid water (F2), as secondary fluid in which the module M can be immersed.

The module M consists of a stack of metal plates 1 assembled together first in layers by diffusion welding preferably using a CIC technique then by laser welding between them or by insertion of combs in the stack then by compression uniaxial hot, as detailed below. Module M can also be produced by additive manufacturing. As visible in this figure 1, this module M which extends along a central axis (X), integrates two collectors 11, 12 respectively for inlet and outlet of the liquid water of the primary fluid (Fl), one being arranged on top of the module along the X axis and the other also being arranged along the X axis of the module but on the bottom. As detailed below, each of the collectors 11, 12 opens onto a side base of the stack of plates 1 onto which the channels of the fluid circuit Fl open but not those of the secondary fluid circuit F2.

The module M also includes two outlet collectors 22 for the fluid F2, arranged on either side of the inlet collector 11 for the fluid Fl at the top of the module. The module M does not include fluid inlet collectors F2 as such, the latter entering directly into the secondary circuit inlet pre-collector from the bottom of the module, as detailed below.

In such a module M, the circulation of fluids (Fl, F2) is therefore counter-current.

The module M according to the exchanger comprises a plurality of plates 1 stacked together, one main face 10 of which delimits the circulation of the fluid Fl and the other main face 20 of which, opposite the main face 10, delimits the circulation of the fluid F2, the arrows symbolizing the circulation of each of the fluids in each plate concerned.

Figure 2 shows the main face 10 of a plate 1, dedicated to the circulation of FL

The main face 10 comprises two supply and distribution zones ZH each forming a fluid pre-collector, arranged on either side of a heat exchange zone ZE.

The channels 13 of a pre-collector ZH are delimited by solid cylindrical pads 14 distributed over the plate surface. Preferably, the solid cylindrical pads 14 are uniformly distributed staggered on the surface of the main face 10 at the pre-collector level. More precisely, this staggered distribution is made according to an identical triangular pattern over the entire surface of the main face 10 at the level of the pre-collector ZH. A distribution in a triangular pattern allows better filling of the volume of the pre-collector by the pads 14 and is preferred to ensure the pressure resistance of the exchanger module. The channels 13 delimited by the solid cylindrical pads 14 open onto the channels 15 of the heat exchange zone ZE which is continuous with the pre-collector. As shown, the channels 15 of the exchange zone are each delimited by a groove 15 separated from each other by a rib 16 and extend along the longitudinal axis (X). Preferably, as shown, they are straight, parallel to each other and extend parallel to the longitudinal axis (X) of module 1.

As detailed below, two adjacent plates 1 with cylindrical studs 14 whose height represents part of the height of a channel 13, are intended to be assembled together with their main faces 10 facing one of the the other to form a sheet 3, the total height of the fluid circulation channel being that cumulative of the pads 14 of the two plates 1 in continuity with one another. The same goes for the ribs 16. The arrangement of the pads 14 makes it possible to guarantee the pressure resistance of the plates 1. The pads 14 make it possible to guarantee a homogeneous distribution of the primary fluid Fl, i.e. liquid water, independently of the geometry of the channels 15 of their heat exchange zone ZE while presenting low thermal inertia and minimizing the addition of pressure losses. In addition, as already mentioned, the studs 14 are sized to guarantee pressure resistance.

With such a main face 10 of a plate 1, as partly illustrated in Figure 2, the liquid water Fl is supplied from the tubular inlet collector 11 to be distributed from the inlet 100 of the channels 13 delimited by the pads 14. The liquid water Fl circulates in the channels 13 around the pads 14 of the inlet pre-collector, to reach the channels 15 of the heat exchange zone ZE then circulates around the pads 14 of the pre-collector outlet to be evacuated through the outlet 101 of the channels 13 then recovered by the tubular outlet collector 12.

Figure 3 shows the main face 20 of a plate 1, dedicated to the circulation of F2.

The main face 20 is opposite the main face 10 of a plate 1.

The main face 20 comprises two supply and distribution zones ZH each forming a fluid pre-collector, arranged on either side of a heat exchange zone ZE.

This main face 20 is delimited by two lateral edges 24, 25 in excess of the flat surface 23 and by two discontinuous longitudinal edges 27, 28, that is to say not continuous between the two side edges 24, 25, and which have the same extra thickness as that of the side edges 24, 25.

The single channel 23 of a pre-collector Zu is delimited by the flat central surface 23 of the plate, an extra-thickness lateral edge 24 or 25 and the two longitudinal edges 27, 28.

The single channel 23 of the exchange zone ZE is, for its part, delimited by the flat central surface 23 and the two discontinuous longitudinal edges 27, 28.

The distance between the lateral edge 24 or 25 and one of the discontinuous longitudinal edges 27 or 28 in excess defines an inlet opening 200 or outlet 201 of the fluid F2.

With such a main face 20 of a plate 1, as partly illustrated in Figure 3, the liquid water F2 is supplied from the inlet openings 200 which constitute a sort of inlet collector, then into the 'single channel 23 of flat surface. The fluid F2 is then directed and guided by the longitudinal edges 27, 28 from the inlet pre-collector, to reach the single channel 23 of flat surface of the heat exchange zone ZE then is directed and guided by the lateral edge 25 of the outlet pre-collector to be evacuated through the outlet openings 201 then to be recovered by the two outlet collectors 22.

Thus, according to the invention, we dispense with all ribs (isthmus) and pads for the secondary fluid circuit F2 and we arrange the inlet 11 and outlet 12 collectors of the primary fluid circuit Fl on the longitudinal ends of stacking.

To achieve this design, the inventors carried out a thermo-hydraulic dimensioning of an exchanger module 1 according to the invention, by computational fluid mechanics (CFM) calculations (in English "Computational Fluid Dynamics" acronym CFD).

Table 2 below explains the geometries of exchange channels on the overall dimensions of an exchanger module M meeting the desired operating conditions for application to an SMR type PWR nuclear reactor, as indicated in Table 1 mentioned in the preamble. [Table 2]

From this table 2, it appears that by removing any rib (isthmus) for the circuit of the secondary fluid F2, or by keeping a single channel with a section equal to 500x2 mm ² , the exchange length is entirely acceptable .

As already indicated, an exchanger module M according to the invention is intended to be immersed in a basin of water which constitutes part of the secondary fluid circuit. Thus, the only pressure acting on the walls of the stack of the secondary fluid circuit corresponds to the isostatic pressure and the pressure losses.

From Table 2, it appears that the pressure losses calculated at 1500 Pa are negligible for the mechanical dimensioning, which clearly validates the inventors' choice to eliminate any rib (isthmus) for the secondary fluid circuit F2.

In addition, due to its immersion, an exchanger module M receives a secondary fluid with admission speeds, that is to say at the inlet openings 200, which are extremely low. This also validates the deletion of any pad in the precollector.

Finally, the choice of a main face 10 with ribs (isthmus) 16 and studs 14 is made to maintain margins in the mechanical dimensioning of the module M, particularly in cases of nominal operation and in anticipation of cases of accidental operation of a PWR nuclear reactor.

We now describe with reference to Figures 4A and 4B a method of manufacturing an exchanger module M according to the invention. makes this design somewhat asymmetrical between the main faces

10 and 20 of the same plate 1, assembly of the module solely by stacking plates 1 which would be welded by diffusion welding by CIC is made impossible.

Indeed, the absence of isthmus (rib) and pad for the secondary fluid circuit would cause the plates to collapse during the application of the CIC cycle.

To overcome this difficulty, we produce layers 3 each consisting of two plates 1 mirrored, that is to say in contact by their pads 14 of their main faces 10, then assembled by CIC. The height of the inlet 100 and outlet 101 openings of the primary fluid Fl as well as that of the channels 13, 15 within the inlet and outlet pre-collectors and the exchange zone is determined by the height of the pads 14 and ribs (isthmus) 16.

We thus obtain unitary layers 3, such as that shown in Figure 4A, with the main exterior faces which are the main faces 20 of the two initial plates 1.

The extra thicknesses of the lateral edges 24, 25 and longitudinal edges 27, 28 which are initially integrated into the plates 1 delimit the height of the channels 23 of the secondary fluid F2. To minimize singular pressure losses, care is taken to ensure that the height H between a lateral edge 24 or 25 and a longitudinal edge 27 or 28 is less than or equal to the width L/2 of the channel 23 considered in the exchange zone. ZE, or between the two longitudinal edges 27, 28.

The layers 3 are stacked on top of each other with two end plates 5 at the ends of the stack 4 defining the exchanger module M.

Then, these layers 3 and end plates 5 are welded together preferably by laser welding (Figure 4B).

Instead of producing plates 1 which incorporate the extra thicknesses from their manufacture, it is possible to plan to produce plates 1 without extra thickness on their main face 20 and to produce the extra thicknesses by means of combs 6, 7 nested in the stack of layers 3 .

Once the nesting has been achieved, the assembly between the layers 3 and the combs 6, 7 is then carried out by uni-axial compression (Uni-axial Diffusion Welding (SDU)) to constitute the exchanger module M, as shown in Figure 5.

The shape of the longitudinal 6 and lateral combs 7 as well as the individual nesting of their teeth 60, 70 between two adjacent layers are shown in Figures 6 to 9.

Figures 10 and 11 illustrate the circulation of the primary fluids Fl and secondary F2 within the assembled stack of layers and end plates 5 of an exchanger module M according to the invention, without its collectors.

Other variants and improvements can be considered without departing from the scope of the invention.

The heights of the discontinuous lateral and longitudinal edges of the main faces 20 of the plates 1 which delimit the circulation of the second fluid F2 can be adapted depending on the application according to the usual sizing rules, mechanical resistance to pressure, pressure losses and of fluid flow distribution.

The geometries of the pads and the periodicity of the pitch of the rectangular, square or triangular pattern of their distribution, are to be determined depending on the application according to the usual sizing rules, mechanical resistance to pressure, pressure losses and distribution of fluid flow in the channels. If in all the examples illustrated, all the main faces 10 of the plates 1 are made with pre-collectors with pads 14, we can consider making only those of a single fluid circuit, the other being able to include classic pre-collectors.

We can consider shapes other than cylindrical pads 14. For example, we can consider elliptical geometries, in the shape of drops of water...

Furthermore, if in the examples illustrated, the channels of the heat exchange zone (ZE) are straight channels, the pre-collector according to the invention is independent of this geometry and we can therefore consider other geometries for the exchange channels (ZE), for example curved, zig-zag, double zig-zag channels, etc. Whatever the geometry chosen, in the end, the depth of the exchange channels determines the height of the pads of the precollector according to the invention.

In the example illustrated, the inlet and outlet collectors 11, 12 respectively, are tubular in shape and arranged along the longitudinal axis of the module. Other arrangements of collecting tubes can also be considered.

Also, if in the example illustrated, inlet collectors as such are not provided for the secondary fluid, these being produced by the inlet openings 200 of the inlet precollector ZH, we can provide d add more, like the outlet collectors 22.

Generally speaking, the collectors of the two circuits are likely to be sized under pressure (pressure difference between two circuits) or not.

Claims

1. Heat exchanger module (M) with at least two fluid circuits, of longitudinal axis (X) comprising a stack of plates (1) defining at least two fluid circuits, at least part of the plates each comprising fluid circulation channels, in which:

- the channels of one of the two circuits, called the first circuit, present:

• at least one supply and distribution zone (ZH) of the first fluid, called the first fluid, from outside the stack, forming a pre-collector of the first fluid, in which the channels (13) are delimited, for each plate, by solid studs (14) distributed over the plate surface and opening out at one of the longitudinal ends of the plate,

• an exchange zone (ZE) continues with the pre-collector in which the channels are delimited, for each plate, each by a groove (15) separated from each other by a rib (16) and extend along the longitudinal axis (X);

• at least one supply and distribution zone (ZH) of the fluid, called the second fluid, from outside the stack, forming a pre-collector of the second fluid, in which the single channel is delimited, for each plate, by the flat central surface of the plate, a lateral edge with excess thickness relative to the flat surface of the plate and the two discontinuous longitudinal edges with the same excess thickness relative to the flat surface of the plate (X) as the lateral edge,

• an exchange zone (ZE) continuous with the pre-collector in which the single channel is delimited, for each plate, by the flat central surface of the plate and the two discontinuous longitudinal edges with the same thickness relative to the flat surface plate (X) than the lateral edge, the distance between the lateral edge and one of the discontinuous longitudinal edges in excess thickness defining an entry or exit opening for the second fluid in the stack.

2. Heat exchanger module according to claim 1, comprising two pre-collectors of the first circuit, each arranged at one of the longitudinal ends of the stack, one of the two pre-collectors forming a pre-collector d the inlet of the first fluid, the other forming an outlet pre-collector of the first fluid.

3. Heat exchanger module according to claim 1 or 2, comprising two pre-collectors of the second circuit, each arranged at one of the longitudinal ends of the stack, one of the two pre-collectors forming a pre-collector of fluid inlet, the other forming a fluid outlet pre-collector.

4. Exchanger module according to one of the preceding claims, comprising at least at one of the longitudinal ends of the stack, a fluid collector (11, 12) opening onto a lateral base of the stack on which the channels of the pre-collector of the first circuit open out but not those of the pre-collector of the second circuit.

5. Exchanger module according to claim 4, comprising at one of the longitudinal ends, a fluid collector forming the inlet collector (11) of the first circuit and at the other of the longitudinal ends, a fluid collector forming the output collector (12) of the first circuit.

6. Exchanger module according to one of the preceding claims, comprising at least on one lateral side of the stack, a fluid collector (22) passing through the stack transversely to the axis (X) and opening onto the channels of the pre-collector of the second circuit but not on those of the first circuit.

7. Exchanger module according to claim 6, comprising on each lateral side of the stack, a fluid collector forming the outlet collector (22) of the second circuit.

8. Exchanger module according to one of the preceding claims, the pads being uniformly distributed staggered on the plate surface of the pre-collector in a triangular pattern.

9. Exchanger module according to one of claims 1 to 7, the pads being uniformly distributed on the plate surface of the pre-collector in a rectangular or square pattern.

10. Exchanger module according to one of the preceding claims, the pads being of generally cylindrical shape.

11. Exchanger module according to one of the preceding claims, the channels (15) of the exchange zone of the first circuit and the second circuit being straight, parallel to each other and which extend parallel to the longitudinal axis (X ).

12. Method for manufacturing a heat exchanger module according to one of the preceding claims, comprising the following steps: al/ producing a plurality of at least two metal plates each comprising:

- on one of the two main faces:

• a continuous exchange zone with the pre-collector in which the channels are each delimited by a groove separated from each other by a rib;

- on the other of the two main faces:

• at least one supply and distribution zone of the second fluid called second fluid, forming a pre-collector of the second fluid, in which the single channel is delimited, by the flat central surface of the plate, a lateral edge in excess thickness by relative to the flat surface of the plate and the two discontinuous longitudinal edges with the same excess thickness relative to the flat surface of the plate as the lateral edge,

• a continuous exchange zone with the pre-collector in which the single channel is delimited by the flat central surface of the plate and the two discontinuous longitudinal edges with the same excess thickness relative to the flat surface of the plate as the lateral edge, the distance between the lateral edge and one of the discontinuous longitudinal edges in excess thickness defining an inlet or outlet opening for the second fluid; b 1/ mirroring with alignment and contact by their main faces of two plates comprising the studs and ribs; cl/ assembly by hot isostatic compression (CIC) of the two plates, so as to obtain a metal sheet; dl/ stacking of the plurality of layers assembled by CIC according to step c/ with placement of an end plate at each longitudinal end of the stack; el/ welding, preferably by laser, of the plurality of layers and end plates stacked so as to obtain the module.

13. Method for manufacturing a heat exchanger module according to one of claims 1 to 11, comprising the following steps: a2/ producing a plurality of at least two metal plates each comprising:

- on one of the two main faces:

- on the other of the two main faces:

14. Use of at least one heat exchanger module according to one of claims 1 to 11, the fluid of the first circuit, as primary fluid being liquid water and the fluid of the second circuit, as as a secondary fluid, also being liquid water.

15. Use according to claim 14, the fluid of the first or second circuit coming from a nuclear reactor.

16. Nuclear installation comprising a pressurized water nuclear reactor, of the SMR type, comprising a plurality of exchanger modules according to one of claims 1 to 11, immersed in liquid water as secondary circuit fluid.