Plate heat exchanger module with plate channels containing a fluid supply and distribution zone limited by pins and thickened edges

Description

technical field

[0001] The present invention relates to a heat exchanger module as defined by the preamble of claim 1, and as disclosed by EP 4 086 556 A.

[0002] The invention relates more particularly to the realization of a new type of heat exchanger module to reduce pressure losses without affecting the uniformity of the distribution of the different internal fluid circulation channels, and while ensuring both good thermal efficiency and satisfactory thermomechanical loading.

[0003] Known heat exchangers comprise either one or two internal fluid circulation channels. In single-circuit exchangers, heat exchange occurs between the circuit and the surrounding fluid in which it is immersed. In exchangers with two or more fluid circuits, heat exchange occurs between the two fluid circuits.

[0004] Chemical reactors are known to operate a continuous process in which a small quantity of co-reactants is simultaneously injected into the inlet of a first fluid circuit, preferably equipped with a mixer, and the resulting chemical product is recovered at the outlet of this first circuit. Among these known chemical reactors, some include a second fluid circuit, usually called a utility circuit, whose function is to thermally control the chemical reaction, either by supplying the heat necessary for the reaction or, conversely, by removing the heat released by it. Such chemical reactors with two fluid circuits and a utility circuit are usually called heat exchanger-reactors.

[0005] The present invention relates both to the implementation of heat exchanger modules with a sole function of heat exchange and incorporating two fluid circuits, and to the implementation of reactor-exchangers. Therefore, the term "heat exchanger module with at least two fluid circuits" should be understood, within the scope of the invention, to include both a heat exchanger module with a sole function of heat exchange and a reactor-exchanger.

[0006] The primary use of a two-fluid heat exchanger module according to the invention is its use with water as one of the two fluids. Advantageously, this can be a liquid-water-to-liquid-water exchange.

[0007] The main application targeted by an exchanger module according to the invention is the exchange of heat between liquid water from a primary circuit, and a secondary circuit of a small or medium power pressurized water reactor (PWR) or SMR (acronym for "Small Modular Reactor"), intended for heat generation.

[0008] For the purposes of this invention, "heat-producing reactor" refers to a nuclear reactor whose power output is primarily dedicated to heat generation. A heat-producing reactor may be entirely dedicated to heat production. However, a small portion of its power output may also be used to generate electricity.

[0009] 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 with high thermal power.

[0010] For the purposes of this invention, "primary fluid" means the usual meaning in thermal engineering, namely the hot fluid which transfers its heat to the secondary fluid which is the cold fluid.

[0011] Conversely, in the context of the invention, "secondary fluid" means the usual meaning in thermal engineering, namely the cold fluid to which heat is transferred from the primary fluid.

[0012] In the main application, the primary fluid is the liquid water from the primary circuit of a PWR reactor, while the secondary fluid is the liquid water from the secondary circuit of said PWR reactor. Previous technique

[0013] Examples of known tube-and-shell heat exchangers include shell-and-tube heat exchangers, in which a bundle of straight or U-shaped or helical tubes is mounted on perforated plates and arranged inside a sealed enclosure called a shell. In these shell-and-tube heat exchangers, one fluid flows inside the tubes while the other flows inside the shell. These shell-and-tube heat exchangers have a large volume and are therefore not very compact.

[0014] Existing plate heat exchangers offer significant advantages over existing tube heat exchangers, particularly in terms of thermal performance and compactness, thanks to a favorable surface area to volume ratio. Compact plate heat exchangers are used in numerous industrial sectors. Within this field, many basic shapes defining heat exchange patterns have been developed.

[0015] The first example is plate heat exchangers incorporating fins, in which a heat exchange pattern is defined by a finned structure. These structures are sandwiched between two metal plates and can have highly varied geometries. The heat exchange pattern can differ between the two fluid circuits of the exchanger. The metal plates are usually joined by brazing or diffusion welding.

[0016] It is also known as corrugated or corrugated plate heat exchangers. The corrugations are created by stamping a plate that separates the two fluid circuits. As a result, the heat exchange pattern is identical for each of the two fluid circuits.

[0017] The fluid flow generated by this type of exchange pattern is three-dimensional and, therefore, very efficient. The plates are joined either by bolting or by perimeter welding (conventional welding or diffusion welding).

[0018] Finally, there are plate heat exchangers with machined grooves, where the machining is either mechanical or electrochemical. The channels defined by the machining are millimeter-sized in cross-section and are most often continuous with a regular zigzag profile. The plates are joined by diffusion welding, particularly hot isostatic compression (HIC), which allows for welding at all contact points between two adjacent plates. This type of plate heat exchanger with machined grooves is therefore inherently very resistant to pressure.

[0019] The patent application entitled "Nuclear installation comprising at least one modular nuclear reactor (SMR) and a reactor vessel well delimiting a water basin in which the SMR reactor block and the heat exchangers between the primary and secondary circuits are immersed."and filed on the same day as this application proposes a new nuclear reactor architecture.

[0020] In this architecture, the heat exchangers between the primary and secondary circuits of a PWR designed for heat generation are arranged around the periphery of the reactor vessel. These components are immersed in a water basin as the secondary circuit fluid. Water circulation in the primary and secondary circuits is achieved by natural convection, without pumps. Primary fluid circulation is achieved by thermosiphon, and secondary fluid circulation is achieved by creating a thermocline within the water basin.

[0021] The inventors of this application had to design the exchangers between the primary and secondary circuits according to this architecture.

[0022] Firstly, they analyzed that the natural convection circulation of water in the primary and secondary circuits has the disadvantage of being relatively sensitive to pressure losses.

[0023] However, the specifications for an immersed heat exchanger as indicated above impose a maximum pressure drop of 2000 Pa for the part of the secondary circuit within the heat exchanger.

[0024] The inventors considered that hot isostatic compression assembled (HCI) plate heat exchangers had various advantages as exchangers between the primary and secondary circuits of the aforementioned reactor, notably because, compared to shell and tube heat exchangers, they are often more compact and less sensitive to vibration.

[0025] More specifically, they analyzed that a heat exchanger module as disclosed in patent application EP4086556A1 was a good candidate for application as a heat exchanger between the primary and secondary circuits of the aforementioned reactor. Indeed, the module described in this patent application offers 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 inertias, for thermomechanical dimensioning during transient operating regimes of the reactor; minimization of the number of inlet manifolds.

[0026] The inventors then performed pressure loss calculations of a module according to this patent application EP4086556A1, using a numerical simulation tool for Computational Fluid Dynamics (CFD), under the operating conditions of the aforementioned heat-producing reactor.

[0027] Table 1 below summarizes these operating conditions for a thermal power exchanged by a module of 4.167 MW. [Table 1] Settings Values Primary circuit water pressure 3 bars Primary circuit inlet temperature 110°C Primary circuit outlet temperature 65°C Primary circuit water flow rate 33.04 kg / s Secondary circuit water pressure 2.5 bars Temperature at the inlet of the secondary circuit 45°C Secondary circuit outlet temperature 90°C Secondary circuit water flow rate 22.12 kg / s

[0028] The calculations carried out indicate that the pressure loss obtained in the secondary circuit is 2455 Pa, of which 1055 Pa is in the grooved exchange channel area and 1400 Pa is in the inlet and outlet pre-manifolds.

[0029] The maximum pressure drop of 2000 Pa required by the specifications is therefore largely exceeded.

[0030] There is therefore a need to further improve plate heat exchanger modules such as that according to patent application EP4086556A1, in particular to reduce pressure losses within the modules, and more specifically in their secondary circuit.

[0031] The purpose of the invention is to address this need. Description of the invention

[0032] To this end, the invention relates to a heat exchanger module with at least two fluid circuits, with a longitudinal axis comprising a stack of plates defining at least two fluid circuits, at least a portion of the plates each comprising fluid circulation channels, in which: The channels of one of the two circuits, called the first circuit, have: at least one fluid supply and distribution zone, called the first fluid, from outside the stack, forming a pre-collector for the first fluid, in which the channels are delimited, for each plate, by solid studs distributed over the plate surface and open at one of the longitudinal ends of the plate; a continuous exchange zone 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 extending along the longitudinal axis; the channels of the other of the two circuits, called the second circuit, have: at least one fluid supply and distribution zone, 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 increased thickness relative to the flat plate surface and the two discontinuous longitudinal edges with the same increased thickness relative to the flat plate surface 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 plate surface and the two discontinuous longitudinal edges with the same increased thickness relative to the flat plate surface as the lateral edge, the distance between the lateral edge and one of the discontinuous longitudinal edges with increased thickness defining an inlet or outlet opening for the second fluid in the stack.

[0033] 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 pre-collector.

[0034] The markers on the first circuit are advantageously full.

[0035] According to an advantageous embodiment, the module includes 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.

[0036] According to this mode, the module advantageously includes at one of the longitudinal ends, a fluid collector forming the inlet manifold of the first circuit and at the other of the longitudinal ends, a fluid collector forming the outlet manifold of the first circuit.

[0037] According to another advantageous embodiment, the module includes on a lateral side of the stack, a fluid collector passing through the stack transversely to the (X) axis and opening onto the channels of the pre-collector of the second circuit but not onto those of the first circuit.

[0038] According to this mode, the module advantageously includes on each lateral side of the stack, a fluid collector forming the outlet collector of the second circuit.

[0039] According to an alternative configuration, the studs are evenly distributed in a staggered pattern on the pre-collector plate surface, according to a triangular pattern.

[0040] According to another alternative, the studs are evenly distributed on the pre-collector plate surface in a rectangular or square pattern.

[0041] Preferably, the posts are generally cylindrical in shape.

[0042] Preferably, the channels in the exchange zone of the first circuit are straight, parallel to each other and extend parallel to the longitudinal axis (X).

[0043] The invention also relates, according to a first alternative, to a method for manufacturing a heat exchanger module which has just been described, comprising the following steps: a1 / production of a plurality of at least two metal plates each comprising: on one of the two main faces: at least one supply and distribution zone for the first fluid, called first fluid, forming a pre-collector for the first fluid, in which the channels are delimited by solid studs distributed over the surface of the plate and open at one of the longitudinal ends of the plate, 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 for the second fluid, called the second fluid, forming a pre-collector for the second fluid, in which the single channel is delimited by the flat central surface of the plate, a lateral edge that is thicker than the flat surface of the plate and the two discontinuous longitudinal edges that are the same thickness 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 that are the same thickness as the lateral edge, the distance between the lateral edge and one of the discontinuous longitudinal edges that are thicker defining an inlet or outlet opening for the second fluid;b1 / mirroring with alignment and contact by their main faces of two plates comprising the studs and ribs; c1 / assembly by hot isostatic compression (HIC) of the two plates, so as to obtain a metallic sheet; d1 / stacking of the plurality of sheets assembled by HIC according to step c / with placement of an end plate at each longitudinal end of the stack; e1 / welding, preferably by laser, of the plurality of stacked sheets and end plates so as to obtain the module.

[0044] The invention also relates, according to a second alternative, to a method for manufacturing a heat exchanger module which has just been described, comprising the following steps: a2 / production of a plurality of at least two metal plates each comprising: on one of the two main faces: at least one supply and distribution zone for the first fluid, called first fluid, forming a pre-collector for the first fluid, in which the channels are delimited by solid studs distributed over the surface of the plate and open at one of the longitudinal ends of the plate, 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 for the second fluid, called the second fluid, forming a pre-collector for 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 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 with the same 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 (HIC) of the two plates, so as to obtain a metallic sheet;d2 / alternating stacking of the plurality of sheets assembled by CIC according to step c / with at each lateral end, the teeth of a metal comb defining a lateral edge thicker than 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 thickness as the lateral edge; e / assembly by hot uniaxial compression (CUC), of the plurality of sheets, combs and end plates stacked so as to obtain the module. ;

[0045] We can also consider producing a heat exchanger module using additive manufacturing.

[0046] The invention also relates to the use of the heat exchanger as described above, the fluid of the first circuit, as the primary fluid, being liquid water and the fluid of the second circuit, as the secondary fluid, also being liquid water.

[0047] The fluid in the first or second circuit may come from a nuclear reactor.

[0048] 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 the one described above.

[0049] Thus, the invention essentially consists of producing a stacked plate exchanger module or plates made by additive manufacturing, of which at least one of the pre-collectors of one of the fluid circuits, called the first circuit, is made with studs distributed on the plate surface which delimit the channels in which the fluid flows before reaching its heat exchange zone and the other of the fluid circuits, called the second circuit is delimited only by the flat surface of a plate and discontinuous lateral and longitudinal edges in excess of thickness with respect to the flat surface.

[0050] The studs of the first circuit and the thickened edges of the second circuit ensure that the plates can withstand pressure while exhibiting low thermal inertia.

[0051] The pads ensure a homogeneous distribution of the fluid by minimizing the addition of pressure losses, regardless of the geometry of the channels in the heat exchange zone.

[0052] The geometric shapes and distribution of the pads can be modified as desired to control the fluid distribution according to the intended application and its constraints, particularly temperature and pressure.

[0053] The density of studs in the pre-collector can also be varied.

[0054] Thanks to the studs according to the invention in place of the bifurcations according to patent FR3054879B 1, we also get rid of the thermal inertia zones ZI as illustrated in figure 1B.

[0055] In addition, the pads allow the definition of exchanger module geometries with a fluid inlet and outlet on the same longitudinal face of the module to obtain a side-by-side module arrangement and minimize the piping lengths between them.

[0056] The absence of studs and isthmuses (ribs separating grooves forming channels) in the secondary circuit significantly reduces pressure losses in the second circuit. This makes the heat exchanger module compatible with applications such as a PWR nuclear reactor designed for heat generation, where the module is immersed in the fluid of its secondary circuit.

[0057] Furthermore, arranging the input and output manifolds at the longitudinal ends of the module stack helps to reduce pressure losses in the first circuit.

[0058] All applications requiring heat exchangers or steam generators can be considered with exchanger modules according to the invention, among which we can mention all types of nuclear reactors GEN 3, GEN 4, SMR (English acronym for "Small Medium Reactor"), urban heating networks, EHT electrolyzers, the oil and gas industry, the solar industry, the chemical industry...

[0059] Other advantages and features will become clearer upon reading the detailed description, which is provided for illustrative purposes only and is not exhaustive, with reference to the following figures. Brief description of the drawings

[0060] [ Fig 1 ] there figure 1 is a perspective and partial cutaway view of a heat exchanger module according to the invention with its manifolds, the figure 1 showing a main face of a plate whose channels and studs are dedicated to the circulation of liquid water as the primary fluid. Fig 2 ] there figure 2 is a front view showing one of the main faces of a plate whose channels and studs are dedicated to the circulation of liquid water as the primary fluid. Fig 3 ] there figure 3 is a front view showing the other of the main faces of the plate according to the figure 2 , whose flat surface is dedicated to the circulation of liquid water as a secondary fluid. Fig 4A] [Fig 4B ] THE Figures 4A, 4B These are perspective views showing steps in a first manufacturing process for a heat exchanger module according to the invention. Fig 5 ] there figure 5 is a perspective view of a heat exchanger module according to the invention manufactured according to a second manufacturing process. Fig 6 ] there figure 6 is a perspective view of a longitudinal comb implemented on one of the longitudinal edges of a heat exchanger module during its manufacture according to the second process. Fig 7 ] there figure 7is a partial perspective view showing the implementation of the longitudinal comb according to the figure 6 within a stack to form a heat exchanger module according to the invention. Fig 8 ] there figure 8 is a perspective view of a lateral comb implemented on one of the longitudinal edges of a heat exchanger module during its manufacture according to the second process. Fig 9 ] there figure 9 is a partial perspective view showing the implementation of the lateral comb according to the figure 8 within a stack to form a heat exchanger module according to the invention. Fig 10 ] there Figure 10 is a perspective and partial cutaway view of a heat exchanger module according to the invention without its manifolds, the Figure 10 illustrating the circulation of the primary fluid within the module. Fig 11 ] there figure 11 is a perspective and partial cutaway view of a heat exchanger module according to the invention without its manifolds, the figure 11illustrating the circulation of the secondary fluid within the module. Detailed description

[0061] 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.

[0062] It is specified that throughout the application, the terms "inlet", "outlet", "upstream", "downstream" are to be understood in relation to the direction of circulation of the fluid considered within a heat exchange module according to the invention.

[0063] The exchanger module M is described as an exchanger module between liquid water as the fluid of a primary circuit (F1) and also liquid water as the fluid of a secondary circuit (F2) of an SMR type PWR nuclear reactor.

[0064] In figure 1We have therefore represented a heat exchanger module M according to the invention with two fluid circuits, which is implemented as an example for an exchange between liquid water (F1), as a primary fluid and liquid water (F2), as a secondary fluid in which the module M can be immersed.

[0065] The M module 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 inserting combs into the stack, and finally by hot uniaxial compression, as detailed below. The M module can also be manufactured by additive manufacturing.

[0066] As seen on this figure 1This module M, which extends along a central axis (X), incorporates two manifolds 11 and 12, respectively for the inlet and outlet of the liquid water from the primary fluid (F1). One manifold is arranged on the top of the module along the X-axis, and the other is also arranged along the X-axis of the module, but on the underside. As detailed later, each of the manifolds 11 and 12 opens onto a lateral base of the plate stack 1, onto which the channels of the fluid circuit F1 open, but not those of the secondary fluid circuit F2.

[0067] Module M also includes two F2 fluid outlet manifolds 22, arranged on either side of the F1 fluid inlet manifold 11 at the top of the module. Module M does not include separate F2 fluid inlet manifolds; the fluid enters directly into the secondary circuit inlet pre-manifold from the bottom of the module, as detailed later.

[0068] In such a module M, the circulation of fluids (F1, F2) is therefore counter-current.

[0069] The module M according to the exchanger comprises a plurality of plates 1 stacked together, of which a main face 10 delimits the circulation of fluid F1 and of which the other main face 20, opposite the main face 10 delimits the circulation of fluid F2, the arrows symbolizing the circulation of each of the fluids in each plate concerned.

[0070] There figure 2 shows the main face 10 of a plate 1, dedicated to the circulation of F1.

[0071] The main face 10 comprises two supply and distribution zones ZH, each forming a pre-collector of the fluid, arranged on either side of a heat exchange zone ZE.

[0072] The channels 13 of a pre-collector ZH are delimited by solid cylindrical studs 14 distributed across the plate surface. Preferably, the solid cylindrical studs 14 are uniformly staggered across the surface of the main face 10 at the pre-collector level. More precisely, this staggered distribution follows an identical triangular pattern across the entire surface of the main face 10 at the pre-collector ZH level. A triangular pattern distribution allows for better filling of the pre-collector volume by the studs 14 and is preferred to ensure the pressure resistance of the heat exchanger module.

[0073] The channels 13, delimited by the solid cylindrical studs 14, open into 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.

[0074] As detailed below, two adjacent plates 1 with cylindrical studs 14, whose height represents a portion of the height of a channel 13, are intended to be joined together with their main faces 10 facing each other to form a sheet 3. The total height of the fluid circulation channel is the sum of the studs 14 of the two continuous plates 1. The same applies to the ribs 16. The arrangement of the studs 14 ensures the pressure resistance of the plates 1. The studs 14 guarantee a homogeneous distribution of the primary fluid F1, i.e., liquid water, regardless of the geometry of the channels 15 in their heat exchange zone ZE, while exhibiting low thermal inertia and minimizing added pressure losses. Furthermore, as already mentioned, the studs 14 are dimensioned to guarantee pressure resistance.

[0075] With such a main face 10 of a plate 1, as is partly illustrated in figure 2 , liquid water F1 is supplied from the inlet tubular manifold 11 to be distributed from the inlet 100 of the channels 13 delimited by the pads 14. Liquid water F1 flows in the channels 13 around the pads 14 of the inlet pre-manifold, to reach the channels 15 of the heat exchange zone ZE then flows around the pads 14 of the outlet pre-manifold to be discharged by the outlet 101 of the channels 13 then recovered by the outlet tubular manifold 12.

[0076] There figure 3 shows the main face 20 of a plate 1, dedicated to the circulation of F2.

[0077] The main face 20 is opposite the main face 10 of a plate 1.

[0078] The main face 20 comprises two supply and distribution zones ZH, each forming a pre-collector of the fluid, arranged on either side of a heat exchange zone ZE.

[0079] This main face 20 is delimited by two lateral edges 24, 25 which are thicker than the flat surface 23 and by two discontinuous longitudinal edges 27, 28, i.e. not continuous between the two lateral edges 24, 25, and which have the same thickness as the lateral edges 24, 25.

[0080] The single channel 23 of a ZH pre-collector is delimited by the flat central surface 23 of the plate, a lateral edge 24 or 25 in excess thickness and the two longitudinal edges 27, 28.

[0081] 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.

[0082] The distance between the lateral edge 24 or 25 and one of the discontinuous longitudinal edges 27 or 28 in excess thickness defines an inlet opening 200 or outlet opening 201 of the fluid F2.

[0083] With such a main face 20 of a plate 1, as is partly illustrated in figure 3 Liquid water F2 is fed from the inlet openings 200, which form a kind of inlet manifold, and then into the single flat-surface channel 23. The fluid F2 is then directed and guided by the longitudinal edges 27, 28 from the inlet pre-manifold, to reach the single flat-surface channel 23 of the heat exchange zone ZE, and then directed and guided by the lateral edge 25 of the outlet pre-manifold to be discharged through the outlet openings 201 and then recovered by the two outlet manifolds 22.

[0084] Thus, according to the invention, we do away with all ribs (isthmuses) and studs for the secondary fluid circuit F2 and we arrange the inlet manifolds 11 and outlet 12 of the primary fluid circuit F1 on the longitudinal ends of the stack.

[0085] To achieve this design, the inventors carried out a thermo-hydraulic dimensioning of an exchanger module 1 according to the invention, by calculations of numerical fluid mechanics (MFN), (in English "Computational Fluid Dynamics" acronym CFD).

[0086] 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] Settings Unit Primary circuit F1 Secondary circuit F2 Width of a plate 1 m 0,5 0,5 Width of an exchange channel m 0,004 0,5 Depth of an exchange channel for a water table 3 m 0,003 0,002 Width of a rib (isthmus) m 0,001 0 Number of heat exchange channels per plate: 1 - 100 1 Pressure drop Pa 1233 1500 Number of plates: 1 61,99 Thickness of the plate stack m 0,496 Length of the ZE exchange zone m 2,204

[0087] From this table 2, it appears that by removing any rib (isthmus) for the secondary fluid circuit F2, i.e. keeping a single channel with a cross-section equal to 500x2 mm 2< , the exchange length is quite acceptable.

[0088] As already mentioned, a heat exchanger module M according to the invention is intended to be immersed in a water basin that forms part of the secondary fluid circuit. Thus, the only pressure acting on the walls of the secondary fluid circuit stack corresponds to the isostatic pressure and pressure losses.

[0089] Table 2 shows that the pressure losses calculated at 1500 Pa are negligible for mechanical sizing, which validates the inventors' choice to eliminate any rib (isthmus) for the secondary fluid circuit F2.

[0090] Furthermore, due to its immersion, an M heat exchanger module receives a secondary fluid with extremely low inlet velocities, i.e., at the 200 inlet openings. This also validates the elimination of any blockage in the pre-manifold.

[0091] Finally, the choice of a main face 10 with ribs (isthmuses) 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 accidental operating cases of a PWR nuclear reactor.

[0092] We are now describing with reference to Figures 4A and 4B a method for manufacturing a heat exchanger module M according to the invention.

[0093] Step i / Due to this somewhat asymmetrical design 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 rendered impossible.

[0094] Indeed, the absence of an isthmus (rib) and a stud for the secondary fluid circuit would cause the plates to sag during the application of the CIC cycle.

[0095] To overcome this difficulty, layers 3 are created, each consisting of two mirrored plates 1, that is, in contact by their studs 14 with their main faces 10, then joined by CIC. The height of the inlet 100 and outlet 101 openings of the primary fluid F1, as well as that of the channels 13, 15 within the inlet and outlet pre-manifolds and the exchange zone, is determined by the height of the studs 14 and ribs (isthmuses) 16.

[0096] This results in three unitary sheets, such as the one shown in the figure 4A , with the main outer faces which are the main faces 20 of the two initial plates 1.

[0097] The overthicknesses 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.

[0098] To minimize singular head 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, i.e. between the two longitudinal edges 27, 28.

[0099] Step ii / : The layers 3 are stacked one on top of the other with two end plates 5 at the ends of the stack 4 defining the exchanger module M.

[0100] Then, these layers 3 and end plates 5 are welded together, preferably by laser welding ( figure 4B ).

[0101] Instead of producing plates 1 which incorporate the extra thicknesses from their manufacture, it is possible 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.

[0102] Once the interlocking is complete, the assembly between the layers 3 and the combs 6, 7 is then carried out by uniaxial compression (Uniaxial Diffusion Welding (UDW)) to form the exchanger module M, as shown in the figure 5 .

[0103] The shape of the longitudinal combs 6 and lateral combs 7, as well as the individual imbrication of their teeth 60, 70 between two adjacent layers, are shown in figures 6 to 9 .

[0104] THE Figures 10 And 11illustrate the circulation of primary fluid F1 and secondary fluid F2 within the assembled stack of sheets and end plates 5 of an exchanger module M according to the invention, without its manifolds.

[0105] Other variations and improvements can be considered without going outside the scope of the invention.

[0106] 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 according to the application according to the usual sizing rules, mechanical resistance to pressures, pressure losses and fluid flow distribution.

[0107] The geometries of the studs and the periodicity of the pitch of the rectangular, square or triangular pattern of their distribution, are to be determined according to the application according to the usual sizing rules, mechanical resistance to pressures, pressure losses and fluid flow distribution in the channels.

[0108] If in all the illustrated examples, all the main faces 10 of the plates 1 are made with stud pre-collectors 14, it is possible to consider making only those of a single fluid circuit, the other being able to include classic pre-collectors.

[0109] We can consider shapes other than cylindrical blocks. For example, we can consider elliptical geometries, or shapes resembling teardrops...

[0110] Furthermore, although in the illustrated examples the heat exchange zone (ZE) channels are straight channels, the pre-collector according to the invention is independent of this geometry and other geometries can therefore be considered for the exchange channels (ZE), for example curved, zig-zag, double zig-zag channels... Whatever the geometry chosen, in the end, the depth of the exchange channels determines the height of the studs of the pre-collector according to the invention.

[0111] In the illustrated example, the inlet and outlet collectors 11 and 12, respectively, are tubular in shape and arranged along the longitudinal axis of the module. Other arrangements of collector tubes are also possible.

[0112] Also, if in the illustrated example, no inlet manifolds as such are provided for the secondary fluid, these being made by the inlet openings 200 of the inlet pre-manifold ZH, it is possible to provide for adding them, like the outlet manifolds 22.

[0113] In general, the manifolds of the two circuits are likely to be sized under pressure (pressure difference between two circuits) or not.

Claims

1. Heat exchanger module (M) having at least two fluid circuits, of longitudinal axis (X) comprising a stack of plates (1) defining at least two fluid circuits, at least a part of the plates each comprising fluid circulation channels, wherein: - the channels of one of the two circuits, referred to as first circuit, have: • at least one zone (ZH) for supplying and distributing the first fluid, referred to as first fluid, from the outside of the stack, forming a pre-header for the first fluid, in which zone the channels (13) are delimited, for each plate, by solid studs (14) distributed over the surface of the plate and open at one of the longitudinal ends of the plate, • an exchange zone (ZE) continuous with the pre-header, in which zone the channels are each delimited, for each plate, by a groove (15), are separated from each other by a rib (16) and extend along the longitudinal axis (X); the heat exchanger module being characterized in that the channels of the other of the two circuits, referred to as second circuit, have: • at least one zone (ZH) for supplying and distributing the fluid, referred to as second fluid, from the outside of the stack, forming a pre-header for the second fluid, in which zone the single channel is delimited, for each plate, by the flat central surface of the plate, a lateral edge with an overthickness relative to the flat surface of the plate and the two discontinuous longitudinal edges with the same overthickness relative to the flat surface of the plate (X) as the lateral edge, • an exchange zone (ZE) continuous with the pre-header, in which zone 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 overthickness relative to the flat surface of the plate (X) as the lateral edge, the distance between the lateral edge and one of the discontinuous longitudinal edges with an overthickness defining an inlet or outlet opening for the second fluid in the stack.

2. Heat exchanger module according to Claim 1, comprising two pre-headers of the first circuit, each arranged at one of the longitudinal ends of the stack, one of the two pre-headers forming an inlet pre-header for the first fluid, the other forming an outlet pre-header for the first fluid.

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

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

5. Exchanger module according to Claim 4, comprising, at one of the longitudinal ends, a fluid header forming the inlet header (11) of the first circuit and, at the other of the longitudinal ends, a fluid header forming the outlet header (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 header (22) passing through the stack transversely to the axis (X) and opening onto the channels of the pre-header of the second circuit but not onto those of the first circuit.

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

8. Exchanger module according to one of the preceding claims, the studs being uniformly distributed in a staggered configuration over the surface of the plate of the pre-header in a triangular pattern.

9. Exchanger module according to one of Claims 1 to 7, the studs being uniformly distributed over the surface of the plate of the pre-header in a rectangular or square pattern.

10. Exchanger module according to one of the preceding clams, the studs being of cylindrical overall shape.

11. Exchanger module according to one of the preceding claims, the channels (15) of the exchange zone of the first circuit and of the second circuit being straight, mutually parallel, and extending 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: a1 / producing a plurality of at least two metal plates each comprising: - on one of the two main faces: • at least one zone for supplying and distributing the first fluid, referred to as first fluid, forming a pre-header for the first fluid, in which zone the channels are delimited by solid studs distributed over the surface of the plate and open at one of the longitudinal ends of the plate, • an exchange zone continuous with the pre-header, in which zone the channels are each delimited by a groove and are separated from each other by a rib; - on the other of the two main faces: • at least one zone for supplying and distributing the second fluid, referred to as second fluid, forming a pre-header for the second fluid, in which zone the single channel is delimited, by the flat central surface of the plate, a lateral edge with an overthickness relative to the flat surface of the plate and the two discontinuous longitudinal edges with the same overthickness relative to the flat surface of the plate as the lateral edge, • an exchange zone continuous with the pre-header, in which zone the single channel is delimited by the flat central surface of the plate and the two discontinuous longitudinal edges with the same overthickness 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 with an overthickness defining an inlet or outlet opening for the second fluid; b1 / placing, with alignment and contact via their main faces, two plates comprising the studs and ribs such that they mirror one another; c1 / assembling the two plates by hot isostatic pressing (HIP), so as to obtain a metal layer; d1 / stacking the plurality of layers assembled by HIP according to step c / with placement of an end plate at each longitudinal end of the stack; e1 / welding, preferably by laser, of the plurality of stacked layers and end plates 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: • at least one zone for supplying and distributing the first fluid, referred to as first fluid, forming a pre-header for the first fluid, in which zone the channels are delimited by solid studs distributed over the surface of the plate and open at one of the longitudinal ends of the plate, • an exchange zone continuous with the pre-header, in which zone the channels are each delimited by a groove and are separated from each other by a rib; - on the other of the two main faces: • at least one zone for supplying and distributing the second fluid, referred to as second fluid, forming a pre-header for the second fluid, in which zone the single channel is delimited by the flat central surface of the plate, • an exchange zone continuous with the pre-header, in which zone the single channel is delimited by the flat central surface of the plate and the two discontinuous longitudinal edges with the same overthickness 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 with an overthickness defining an inlet or outlet opening for the second fluid; b2 / placing, with alignment and contact via their main faces, two plates comprising the studs and ribs such that they mirror one another; c2 / assembling the two plates by hot isostatic pressing (HIP), so as to obtain a metal layer; d2 / alternately stacking the plurality of layers assembled by HIP according to step c / with, at each lateral end, the teeth of a metal comb defining a lateral edge with an overthickness 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 overthickness relative to the flat surface of the plate as the lateral edge; e / assembling, by uniaxial hot pressing (UHP), the plurality of stacked layers, combs and end plates so as to obtain the module.

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 secondary fluid, also being liquid water.

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

16. Nuclear facility 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 fluid of the secondary circuit.