Brazed plate heat exchanger with freeze detection system

Abstract

The brazed plate heat exchanger (10) comprises a plurality of heat exchanger plates (12A, 12B, 12C) stacked on top of each other. The heat exchanger plates (12A, 12B, 12C) are obtained by forming them from their respective metal sheets and are permanently joined to each other by brazing with brazing material to form a plate package (30) having a first plate space (32) for a first fluid and a second plate space (34) for a second fluid. Each of the heat exchanger plates (12A, 12B, 12C) comprises a plurality of port holes (P1, P2, P3, P4) and one or more side edges (26, 28) that form the outer periphery of the heat exchanger plate (12A, 12B, 12C). The brazed plate heat exchanger (10) comprises a plurality of cells (36) having a predetermined internal volume (V). Each cell (36) is integrated with the corresponding heat exchanger plate (12A, 12B, 12C) and is separated by a first plate space (32) and / or a second plate space (34) through its respective deformable wall portion (38). The deformable wall portion (38) has a mechanical strength lower than the average mechanical strength of the metal sheets of the heat exchanger plate (12A, 12B, 12C). At least one channel (40) is provided between each cell (36) and one of the side edges (26, 28) of the heat exchanger plate (12A, 12B, 12C), and each channel (40) fluidly connects the internal volume (V) of each cell (36) to the environment outside the brazed plate heat exchanger (10).

Description

Technical Field

[0001] The present invention generally refers to a plate heat exchanger, and more specifically to a brazed plate heat exchanger used as an evaporator, wherein the heat exchanger plates are provided with an improved system for detecting freezing of at least one of two fluids flowing inside the heat exchanger.

Background Art

[0002] A heat exchanger is a device used to transfer heat between two or more fluids. A plate heat exchanger is a specific type of heat exchanger that uses metal plates to transfer heat between two fluids. A plate-type heat exchanger generally includes a starting plate, an ending plate, and a plurality of intermediate plates stacked on top of each other to form flow paths therebetween. In a plate-type heat exchanger, two fluids at different temperatures (one of which is usually identified as a refrigerant fluid) flow through flat channels obtained between the opposing surfaces of pairs of adjacent heat exchanger plates. In this way, the two fluids exchange their heat capacities. These fluids may flow in countercurrent or parallel flow, and their leak-free circulation is ensured by gaskets or joints between the heat exchanger plates.

[0003] The flow paths between the heat exchanger plates are usually obtained by providing a corrugated pattern on both flat surfaces. In other words, both flat surfaces have a pattern of ridges and grooves pressed thereon. When the heat exchanger plates are stacked on top of each other, the ridges of the first heat exchanger plate contact the grooves of the adjacent heat exchanger plate, and thus, these plates are kept at a distance from each other through spacer elements. In this way, the flow paths are formed.

[0004] The usual method for manufacturing flat-plate heat exchangers is to braze the heat exchanger plates together. This method requires that the heat exchanger plates be covered with brazing material. During the manufacturing process, the heat exchanger plates are stacked on top of each other and placed in a furnace that is hot enough to melt the brazing material at least partially. After the furnace temperature is lowered, the brazing material solidifies, joining the heat exchanger plates together and making it possible to form a small, strong heat exchanger.

[0005] Brazed plate heat exchangers, also known by the acronym "BHE," can be used as evaporators. When a brazed plate heat exchanger is used as an evaporator, the first fluid, usually water, loses heat and cools into a second fluid, i.e., a refrigerant fluid, and the second fluid evaporates. Under specific conditions of low temperature and fluid flow, freezing can occur in the water circuit of a BHE evaporator. Because the temperature and flow of the fluid change within the channel area, ice formation occurs gradually, and therefore the duration of these dangerous conditions is another important parameter to consider.

[0006] The flow path of a BHE evaporator can withstand the freezing of water without any problems, even under the dangerous conditions described above. However, if some water becomes trapped in a closed space and freezes instantaneously, causing volume expansion, this situation becomes dangerous to the mechanical integrity of the BHE evaporator. This can occur, for example, because previously formed ice can create an ice plug around the water. The volume of ice expands by about 7% compared to the volume occupied by the water. When trapped, the ice exerts very strong pressure on the wall (in this case, a flat surface) that is limiting the ice. Another effect is that as the ice expands, it creates a "piston effect" on the trapped water, increasing the water pressure.

[0007] Plate failure rarely occurs when the initial freezing takes place. Typically, a few (but not many) freeze-thaw-freeze cycles are required. In any case, repairing the system after BHE evaporator failure caused by freezing is costly and time-consuming. In addition, it must be considered that potentially environmentally harmful refrigerants (i.e., flammable, toxic, and / or with high GWP values) typically circulate within the BHE evaporator. For these reasons, the release of refrigerants into the environment must be avoided for safety and environmental reasons.

[0008] To avoid or reduce the risk of failure, the plates of BHE evaporators for low-temperature fluid applications are designed according to certain rules to avoid the formation of areas where water can accumulate as much as possible. In addition, operating condition limits (including parameters on fluid temperature, fluid flow rate, and duration) are determined for specific BHE evaporators and applications. However, the actual operating conditions of BHE evaporators are often difficult to predict and control. For example, the actual water flow rate is often unknown. There may also be failures in the BHE evaporator's control system, or incorrect settings (e.g., the water limit temperature being too low), or a combination of all of these factors.

[0009] Document Chinese Patent Application Publication No. 113432461 discloses a brazed plate heat exchanger in which the heat exchanger plate has specific joints that function as ice-breaking points. These joints need to be surrounded by elastically deformable surfaces of channels through which a liquid that may be prone to freezing flows. Therefore, brazed plate heat exchangers require a complex and expensive manufacturing process to achieve ice-breaking points.

[0010] Document No. 203274588 of the Chinese Utility Model Patent discloses a brazed plate heat exchanger having a built-in groove with a temperature sensor. The temperature sensor is intended to indicate the possibility of the fluid freezing. However, there is only one temperature sensor, and it is positioned at a specific location in the heat exchanger, and is therefore positioned to detect the fluid temperature only at that specific location. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Chinese Patent Application Publication No. 113432461 Specification [Patent Document 2] China Utility Model No. 203274588 Specification [Overview of the project] [Problems that the invention aims to solve]

[0012] Therefore, one object of the present invention is to provide a brazed plate heat exchanger that can overcome the shortcomings of the prior art in a simple, inexpensive, and particularly functional way.

[0013] More specifically, one object of the present invention is to provide a brazed plate heat exchanger, which is used particularly as an evaporator, that can warn the factory owner, and therefore the heat exchanger manufacturer, as soon as possible after the first freezing occurs, when freezing occurs in the heat exchanger due to operating conditions, provided that the damage is limited and there is no breakage of the heat exchanger or leakage of the refrigerant.

[0014] Another object of the present invention is to provide a brazed plate heat exchanger that allows the factory owner to perform corrective actions to bring the operating parameters back within acceptable limits and to set the control parameters accordingly. [Means for solving the problem]

[0015] These and other objectives are achieved in accordance with the present invention by providing a brazed plate heat exchanger as described in the appended claims.

[0016] Further features of the present invention are highlighted by the dependent claims, which are integral parts of this description.

[0017] The brazed plate heat exchanger according to the present invention comprises a plurality of heat exchanger plates stacked on top of each other. The heat exchanger plates are obtained by forming each plate from a metal sheet. The heat exchanger plates are permanently joined to each other by brazing with a brazing material to form a plate package comprising a first plate space for a first fluid and a second plate space for a second fluid. Each heat exchanger plate comprises a plurality of port holes and one or more side edges forming the outer perimeter of the heat exchanger plate. The heat exchanger comprises a plurality of cells having predetermined internal volumes, each cell being integral with the corresponding heat exchanger plate and separated by the first plate space and / or the second plate space through its respective deformable wall portion. The deformable wall portion has a mechanical strength lower than the average mechanical strength of the metal sheet of the heat exchanger plate. At least one channel is provided between each cell and one of the side edges of the heat exchanger plate. Each channel fluidly connects the internal volume of the respective cell to the environment outside the heat exchanger.

[0018] Preferably, each cell is positioned near one of the side edges of the heat exchanger plate. Always preferably, each cell is positioned between one of the port holes and one of the side edges of the heat exchanger plate.

[0019] According to a preferred embodiment of the present invention, the deformable wall portion has an average thickness thinner than the average thickness of the metal sheets of the heat exchanger plate. Alternatively, according to another preferred embodiment of the present invention, the deformable wall portion comprises one or more bends having small radii. As a further alternative, according to a further preferred embodiment of the present invention, the deformable wall portion is made of a different metal material than the metal material from which the metal sheets of the heat exchanger plate are made.

[0020] According to a preferred embodiment, at least a portion of the cell is provided with sensor means for detecting deformation and / or damage to the deformable wall portion associated with each cell. Preferably, the sensor means are - A colored fluid substance having a viscosity greater than that of the first fluid and the second fluid, wherein the colored fluid substance is arranged to at least partially fill the internal volume of a single cell and to leak out of the respective channels if a deformable wall portion deforms and / or breaks, - At least one conductive fluid material that at least partially fills the internal volume of a single cell, and at least one conductive cable connecting the internal volume of this single cell through its respective channels to an electronic control unit of a heat exchanger, wherein the conductive fluid material is arranged to generate an electrical signal and transmit it through the cable to the electronic control unit when a deformable wall portion deforms and / or breaks, - An elastic element in direct contact with a deformable wall portion of a single cell, and at least one conductive cable in direct contact with the elastic element, connecting the internal volume of the single cell through its respective channels to an electronic control unit of a heat exchanger, wherein elastic deformation of the elastic element occurs when the deformable wall portion deforms and / or breaks, and this elastic deformation generates an electrical signal which is transmitted through the cable to the electronic control unit. It can be equipped with.

[0021] According to a preferred embodiment of the present invention, the heat exchanger comprises pairs of adjacent cells, where the two cells of a single pair of adjacent cells are respectively arranged in two adjacent first plate spaces and / or two adjacent second plate spaces. The two cells of a single pair of adjacent cells are separated from each other and from the adjacent first plate spaces and / or adjacent second plate spaces by at least one deformable wall portion.

[0022] Preferably, pairs of adjacent cells are interconnected through connecting pipelines, and the connecting pipelines are, in turn, fluid-connected through at least one of the channels to a single lateral opening obtained at one of the lateral ends of the heat exchanger plates. More preferably, these pairs of adjacent cells and the connecting pipelines are filled with an inert gas. Even more preferably, at least one probe is connected to the lateral opening. This probe can detect changes in the pressure and / or temperature values of the inert gas.

[0023] According to a further preferred embodiment of the invention, the heat exchanger comprises one or more fluid collection tanks, which are arranged outside the heat exchanger and are designed to collect the fluid exiting the heat exchanger through at least one of the channels. The fluid collection tank preferably comprises one or more fluid level sensors and / or one or more overflow discharge pipelines.

[0024] The features and advantages of the brazed plate heat exchanger according to the invention will become more apparent from the following illustrative and non-limiting description, with reference to the accompanying schematic drawings.

Brief Description of the Drawings

[0025] [Figure 1] It is a side view of a general embodiment of the brazed plate heat exchanger. [Figure 2] It is a plan view of the brazed plate heat exchanger of FIG. 1. [Figure 3] It is a schematic partial cross-sectional view of the brazed plate heat exchanger of FIG. 1, showing the main components of the freezing detection system according to the invention in its first embodiment. [Figure 4] It is a schematic perspective view of the components of the freezing detection system. [Figure 5] It is another schematic partial cross-sectional view of the brazed plate heat exchanger of FIG. 1, showing the main components of the freezing detection system according to the invention in its second embodiment. [Figure 6A] It is a diagram showing possible locations of the components of the freezing detection system. [Figure 6B] This diagram shows the possible locations of the components of the freeze detection system. [Figure 7] Figure 1 is another partial cross-sectional view of the brazed flat plate heat exchanger, illustrating the operation of the freeze detection system according to the present invention. [Figure 8] Figure 1 is another partial cross-sectional view of the brazed plate heat exchanger, showing further components of the freeze detection system. [Figure 9] Figure 1 is another partial cross-sectional view of the brazed plate heat exchanger, in which the main components of the freeze detection system are shown in the third embodiment. [Figure 10] Figure 9 is a cross-sectional view showing the operation of the freeze detection system. [Figure 11] Figure 9 is another cross-sectional view showing the operation of the freeze detection system. [Figure 12] Figure 9 is another cross-sectional view showing other components of the freeze detection system. [Figure 13] This is a schematic diagram showing further components of the freeze detection system according to the present invention. [Modes for carrying out the invention]

[0026] Referring particularly to Figures 1 and 2, a brazed plate heat exchanger 10 is shown. The heat exchanger 10 comprises a plurality of heat exchanger plates 12A, 12B, 12C stacked on top of each other in a manner known by itself. Typically, the heat exchanger plates 12A, 12B, 12C are stacked on top of each other between a first end plate 14 and a second end plate 16 of the heat exchanger 10. Each heat exchanger plate 12A, 12B, 12C is obtained by forming it from its respective metal sheet. The first end plate 14, the second end plate 16, and the heat exchanger plates 12A, 12B, 12C are permanently joined to each other through brazing with a brazing material to form a plate package 30. The plate package 30 thus comprises a first plate space 32 for a first fluid and a second plate space 34 for a second fluid (see, for example, Figure 3). The first and second fluids may be any suitable heat transfer fluids. For example, the first fluid may be a hotter fluid, and the second fluid may be a colder fluid. The second fluid is therefore a cooling fluid, and it receives heat from the first fluid. More specifically, when the heat exchanger 10 is used as an evaporator, the first fluid may be water, and the second fluid may be a refrigerant fluid.

[0027] Each heat exchanger plate 12A, 12B, 12C, as well as the first end plate 14 and the second end plate 16, are provided with a plurality of port holes, preferably four port holes P1, P2, P3, and P4. The first port hole P1 is connected to the first connecting pipe 18 and communicates with the first flat plate space 32. The second port hole P2 is connected to the second connecting pipe 20 and communicates with the first flat plate space 32. The third port hole P3 is connected to the third connecting pipe 22 and communicates with the second flat plate space 34. Finally, the fourth port hole P4 is connected to the fourth connecting pipe 24 and communicates with the second flat plate space 34. The connecting pipes 18, 20, 22, and 24 can be provided extending from the first end plate 14 and / or from the second end plate 16, as shown in Figure 1.

[0028] Each heat exchanger plate 12A, 12B, 12C, as well as the first end plate 14 and the second end plate 16, can have the shape of any planar figure enclosed by closed lines, such as a convex polygon or a circle. Each heat exchanger plate 12A, 12B, 12C, as well as the first end plate 14 and the second end plate 16, thus have one or more side edges 26, 28 that form the outer perimeter of the heat exchanger plates 12A, 12B, 12C, 14, 16. Preferably, as shown in Figures 1 and 2, each heat exchanger plate 12A, 12B, 12C, as well as the first end plate 14 and the second end plate 16, has a substantially rectangular shape with two longitudinal side edges 26 and two short side edges 28, as shown in Figure 2. The longitudinal axis X extends parallel to the two longitudinal side edges 26 and across the two short side edges 28.

[0029] According to the present invention, the heat exchanger 10 comprises a plurality of hollow structures or cells 36 having a predetermined internal volume V. Each cell 36 is integral with the corresponding heat exchanger plates 12A, 12B, 12C and is separated by a first plate space 32 and / or a second plate space 34 through its respective deformable wall portion 38. In other words, each cell 36 is confined by its respective deformable wall portion 38 to one of the first plate spaces 32 and / or one of the second plate spaces 34. Each cell 36 is then sealed from the first plate space 32 and / or the second plate space 34 by one or more flat brazed joints. For example, as shown in Figure 3, a cell 36 can be brought into contact with the first plate space 32 of the heat exchanger 10, through which a first fluid that may freeze, such as water, flows.

[0030] The deformable wall portion 38 that partially encloses the internal volume V surrounded by cell 36 has a mechanical strength lower than the average mechanical strength of the metal sheets of the heat exchanger plates 12A, 12B, and 12C. In mechanics of materials, the expression "mechanical strength" refers to the ability of a material to withstand an applied load without fracture or plastic deformation. In this application, the expression "lower mechanical strength" means that the deformable wall portion 38 is mechanically weaker than the wall portion surrounding the plate space 32 and / or 34 between the heat exchanger plates 12A, 12B, and 12C. In other words, the deformable wall portion 38 is the first wall portion of the plate space 32 and / or 34 that will deform or break due to the formation of ice I under hazardous conditions (Figure 3). At the same time, these deformable wall portions 38 are strong enough to withstand the normal pressure of the fluid (water W, see Figure 3) flowing through the plate space 32 and / or 34.

[0031] In several ways, a lower mechanical strength for the deformable wall portion 38 relative to the other wall portions of the heat exchanger plates 12A, 12B, and 12C may be obtained. For example, the deformable wall portion 38 may have an average thickness thinner than the average thickness of the metal sheets of the heat exchanger plates 12A, 12B, and 12C. Alternatively or additionally, the deformable wall portion 38 may have one or more bends with small radii. As a further alternative, the deformable wall portion 38 may be made from a different metal material than the metal material from which the metal sheets of the heat exchanger plates 12A, 12B, and 12C are made. A further possible alternative for obtaining a lower mechanical strength for the deformable wall portion 38 may be to increase the distance between the continuous brazed joints connecting each cell 36 to the first flat plate space 32 and / or the second flat plate space 34.

[0032] The deformation of the wall portion 38 and therefore each cell 36 absorbs the portion of the increasing fluid volume, resulting in a simple, limited, and easily recoverable malfunction for the heat exchanger 10 and the plant in which the heat exchanger operates. The advantage is that even if slightly damaged, the heat exchanger 10 can continue to operate without leaking and does not need to be replaced. The deformation of the wall portion 38 and therefore each cell 36 can be used as a signal that dangerous freezing conditions have been reached in the flat space 32 and / or 34 of the heat exchanger 10. Due to this deformation, the heat exchanger 10 can only operate effectively once (or a few times). However, it is recommended to repair the damaged heat exchanger 10 as soon as possible, mainly to avoid one of the two fluids, typically the refrigerant, being released into the environment. Generally, regulations stipulate that once freezing is detected in that manner for the first time, the plant owner must reset and upgrade the plant's operating conditions to restore safe operating conditions and prevent those dangerous conditions from being reached again at any other time in the future.

[0033] As better illustrated in Figure 4, at least one channel 40 is provided between each cell 36 and one of the side edges 26, 28 of the heat exchanger plates 12A, 12B, and 12C. Each channel 40 fluidly connects the internal volume V of each cell 36 to the environment outside the heat exchanger 10. Each channel 40 is a small-radius channel, like a nozzle. The advantage of the channel 40 is that even if the wall portion 38 and thus the corresponding cell 36 are damaged due to freezing, the subsequently molten fluid (water W) leaks out to the outside through the corresponding channel 40 (see Figure 7). When this occurs, the static pressure of the water circuit drops, which can also be a signal of a problem. Due to the low pressure and the non-hazardous fluid (water), water leakage through the channel 40 is easy to detect and then repair (e.g., by sealing the channel 40 with adhesive). As with deformation conditions that work for one instance, here any corrective action is needed to the operating parameters of the heat exchanger 10 and / or the entire plant.

[0034] Figures 6A and 6B show two possible locations for a single cell 36 and their respective channels 40. For example, each cell 36 can be located near one of the side edges 26, 28 of the heat exchanger plates 12A, 12B, and 12C. Alternatively, or in addition, each cell 36 can be located between one of the port holes P1, P2, P3, and P4 and one of the side edges 26, 28 of the heat exchanger plates 12A, 12B, and 12C. Generally, the location of the cell 36 can be determined according to fluid dynamics analysis (which can be done using fluid dynamics software, laboratory work, and field test results, etc.). If necessary, more than one cell 36 can be located at different points on the heat exchanger plates 12A, 12B, and 12C.

[0035] According to a preferred embodiment of the present invention, at least a portion of the cell 36 may be equipped with sensor means for detecting deformation and / or damage to the deformable wall portions 38 associated with each cell 36. The sensor means can be located inside the cell 36 and / or with the cell 36, several embodiments thereof are schematically shown in Figure 8. When water W freezes, the water W increases in volume, causing the wall portions 38 of the cell 36 to deform elastically or permanently, or even to break. Thus, the sensor means functions as part of a freeze detection system to detect deformation and / or damage and issue a warning signal.

[0036] The sensor means may be of various types. For example, as shown in Figure 8, the sensor means may comprise at least one colored fluid substance 42 having a viscosity greater than the viscosity of the first and second fluids flowing into the heat exchanger 10. This colored fluid substance 42 may be a high-viscosity, colored, grease-like substance. This colored fluid substance 42 is arranged to at least partially fill the internal volume V of a single cell 36 and to leak out through the respective channels 40 if the respective deformable wall portion 38 deforms and / or breaks. In other words, once the cell 36 is compressed and / or the respective deformable wall portion 38 deforms or breaks, this colored fluid substance 42 is pushed out of the heat exchanger 10 through the respective channels 40 and becomes visible on the outside.

[0037] According to a different embodiment, as also shown in Figure 8, the sensor means may comprise at least one conductive fluid material 44 that at least partially fills the internal volume V of a single cell 36, and at least one conductive cable 46 that connects the internal volume V of the single cell 36 to an electronic control unit 50 of the heat exchanger 10 through its respective channel 40. The conductive fluid material 44 is arranged to generate an electrical signal and transmit it to the electronic control unit 50 through the cable 46 when a deformable wall portion 38 of the cell 36 deforms and / or breaks. For example, the conductive fluid material 44 may be a grease-like conductive material that is pressed toward the conductive cable 46 to short-circuit (close the circuit) its wire end.

[0038] In a further embodiment, as still shown in Figure 8, the sensor means may comprise at least one elastic element 48 in direct contact with a deformable wall portion 38 of a single cell 36, and at least one conductive cable 46 in direct (physical) contact with the elastic element 48, connecting the internal volume V of the single cell 36 through its respective channel 40 to the electronic control unit 50 of the heat exchanger 10. When the deformable wall portion 38 deforms and / or breaks, elastic deformation occurs in the elastic element 48, and this elastic deformation generates an electrical signal which is transmitted to the electronic control unit 50 through the cable 46. For example, the elastic element 48 may be a spring that is pushed toward the conductive cable 46 to short-circuit (close the circuit) its wire end, or some mechanical / electrical / electronic element.

[0039] As shown in the embodiment of Figure 9, the heat exchanger 10 can advantageously provide pairs of adjacent cells 36 obtained on either side of a dividing wall between two adjacent first plate spaces 32 and / or between two adjacent second plate spaces 34. Thus, two cells 36 of a single pair of adjacent cells 36 are respectively located in two adjacent first plate spaces 32 and / or two adjacent second plate spaces 34. These two cells 36 of a single pair of adjacent cells 36 are separated from each other and from the adjacent first plate spaces 32 and / or adjacent second plate spaces 34 by at least one deformable wall portion 38.

[0040] Preferably, as shown in Figure 10, pairs of adjacent cells 36 are connected to each other through connecting conduits 52. The connecting conduits 52 are fluidly connected through at least one of the channels 40 to a single transverse opening 54 obtained at one of the side ends 26, 28 of the heat exchanger plates 12A, 12B, 12C. If one or more deformable wall portions 38 of the cells 36 are damaged by ice formation, leaked water fills all of these cells 36, and therefore, regardless of which cells 36 are actually contained, the leaked water is always directed to a single point on the heat exchanger 10, i.e., a single transverse opening 54. Thus, having only one point of leakage to the outside makes it easier to detect and even sense the leak. In the embodiments described above, the transverse opening 54 can also be easily sealed to stop the water leak and allow the heat exchanger 10 to operate until planned repairs are made. For example, the sensor means described herein can send an appropriate signal to the electronic control unit 50 to activate an "emergency mode," allowing the heat exchanger 10 to continue operating under certain limitations. This would prevent any further freezing inside the heat exchanger 10 (e.g., by shutting off defrosting of the external coils, raising the minimum water temperature setpoint, or lowering the compressor speed). In this way, the heat exchanger 10 can remain operational and provide at least some heating or cooling until its planned repair / replacement.

[0041] Referring to Figure 12, all cells 36 and their respective connecting conduits 52 can be filled with inert gas. At least one probe 56 can be connected to the lateral opening 54. The probe 56 may be a pressure or temperature sensor capable of detecting changes in the pressure and / or temperature values ​​of the inert gas. The probe 56 is thus capable of detecting when the volume of the cell 36 has changed due to deformation and / or breakage caused by ice formation.

[0042] Referring to Figure 13, further components of the freeze detection system according to the present invention are shown. These components comprise one or more fluid collection tanks 58, 60, which are located outside the heat exchanger 10 and are designed to collect fluid exiting the heat exchanger 10 through at least one of the channels 40. More precisely, the first collection tank 58 may be designed to collect fluid exiting multiple channels 40 of the heat exchanger 10 according to the embodiment of Figure 3, while the second collection tank 60 may be designed to collect fluid exiting a single channel 40 and a single lateral opening 54 of the heat exchanger 10 according to the embodiment of Figure 10. Preferably, at least one of the collection tanks 58, 60 may be equipped with one or more fluid level sensors 62 and / or one or more overflow discharge lines 64 to monitor the amount of fluid and discharge any excess as needed.

[0043] Thus, it is understood that the brazed plate heat exchanger according to the present invention achieves the objectives outlined above.

[0044] The brazed plate heat exchanger of the present invention, thus conceived, is open to many modifications and variations, all of which fall within the same conceptual framework, and moreover, all of its details can be replaced by technically equivalent elements. In practice, the materials used, as well as the shape and size, may be of any type according to the technical requirements.

[0045] Therefore, the scope of protection of the present invention is defined by the enclosed claims. [Explanation of Symbols]

[0046] 10. Brazed flat plate heat exchanger 12A heat exchanger plate 12B Heat exchanger plate 12C heat exchanger plate 14. First end plate 16. Second End Version 18. First connecting pipe 20 Second connecting pipe 22 Third connecting pipe 24. Fourth connecting pipe 26 Longitudinal end of flat plate 28 Flat plate short side end 30 flat plate packages 32 The first flat space 34 The second flat space 36 cells 38 Deformable wall section 40 channels 42 Colored fluid substances 44 Conductive Fluid Substances 46 Conductive Cables 48 Elastic elements 50 Electronic control units 52 Connecting conduits 54 Horizontal opening 56 probes 58 First fluid collection tank 60 Second fluid collection tank 62 Fluid level sensor 64 Overflow discharge pipeline P1 First porthole P2 Second Porthole P3 Third Porthole P4 The fourth porthole

Claims

1. A brazed flat plate heat exchanger (10) comprising a plurality of heat exchanger plates (12A, 12B, 12C) stacked on top of each other, wherein the heat exchanger plates (12A, 12B, 12C) are obtained by forming them from metal sheets, and the heat exchanger plates (12A, 12B, 12C) form a flat plate package (30) comprising a first flat plate space (32) for a first fluid and a second flat plate space (34) for a second fluid. The heat exchanger plates (12A, 12B, 12C) are permanently joined to each other through brazing with brazing material, each of the heat exchanger plates (12A, 12B, 12C) has a plurality of port holes (P1, P2, P3, P4), and each of the heat exchanger plates (12A, 12B, 12C) has one or more side edges (26, 28) that form the outer circumference of the heat exchanger plate (12A, 12B, 12C), and the brazed flat plate heat exchanger (10) is predetermined A brazed plate heat exchanger (10) comprising a plurality of cells (36) having a defined internal volume (V), each cell (36) being integral with a corresponding heat exchanger plate (12A, 12B, 12C), each cell (36) being separated by the first plate space (32) and / or the second plate space (34) through its respective deformable wall portion (38), the deformable wall portion (38) having a mechanical strength lower than the average mechanical strength of the metal sheet of the heat exchanger plate (12A, 12B, 12C), and at least one channel (40) provided between each cell (36) and one of the side ends (26, 28) of the heat exchanger plate (12A, 12B, 12C), each channel (40) being characterized by fluidly connecting the internal volume (V) of each cell (36) to the environment outside the brazed plate heat exchanger (10).

2. The brazed flat plate heat exchanger (10) according to claim 1, characterized in that each cell (36) is located near one of the side ends (26, 28) of the heat exchanger plate (12A, 12B, 12C).

3. The brazed flat plate heat exchanger (10) according to claim 1 or 2, characterized in that each cell (36) is positioned between one of the port holes (P1, P2, P3, P4) and one of the side ends (26, 28) of the heat exchanger plate (12A, 12B, 12C).

4. The brazed flat plate heat exchanger (10) according to any one of claims 1 to 3, characterized in that the deformable wall portion (38) has an average thickness thinner than the average thickness of the metal sheets of the heat exchanger plates (12A, 12B, 12C).

5. The brazed flat plate heat exchanger (10) according to any one of claims 1 to 4, characterized in that the deformable wall portion (38) comprises one or more bends having a small radius.

6. The brazed flat plate heat exchanger (10) according to any one of claims 1 to 5, characterized in that the deformable wall portion (38) is made of a different metal material from the metal material from which the metal sheets of the heat exchanger plates (12A, 12B, 12C) are made.

7. A brazed plate heat exchanger (10) according to any one of claims 1 to 6, characterized in that at least a portion of the cell (36) is provided with sensor means (42, 44, 46, 48) for detecting deformation and / or damage of the deformable wall portion (38) associated with the cell (36).

8. The brazed plate heat exchanger (10) according to claim 7, wherein the sensor means comprises at least one colored fluid substance (42) having a viscosity greater than the viscosity of the first fluid and the second fluid, the colored fluid substance is arranged to at least partially fill the internal volume (V) of a single cell (36) and to leak out of each of the channels (40) in the event of deformation and / or breakage of the deformable wall portion (38).

9. The brazed plate heat exchanger (10) according to claim 7, wherein the sensor means comprises at least one conductive fluid material (44) that at least partially fills the internal volume (V) of a single cell (36), and at least one conductive cable (46) that connects the internal volume (V) of the single cell (36) to an electronic control unit (50) of the brazed plate heat exchanger (10) through the respective channels (40), and the conductive fluid material (44) is arranged to generate an electrical signal and transmit it through the cable (46) to the electronic control unit (50) in the event of deformation and / or damage of the deformable wall portion (38).

10. The brazed plate heat exchanger (10) according to claim 7, wherein the sensor means comprises at least one elastic element (48) in direct contact with the deformable wall portion (38) of a single cell (36), and at least one conductive cable (46) in direct contact with the elastic element (48) and connects the internal volume (V) of the single cell (36) to an electronic control unit (50) of the heat exchanger (10) through each of the channels (40), wherein elastic deformation of the elastic element (48) occurs in the event of deformation and / or damage of the deformable wall portion (38), and the elastic deformation generates an electrical signal which is transmitted to the electronic control unit (50) through the cable (46).

11. A brazed plate heat exchanger (10) according to any one of claims 1 to 10, comprising a pair of adjacent cells (36), wherein the two cells (36) of a single pair of adjacent cells (36) are respectively arranged in two adjacent first plate spaces (32) and / or two adjacent second plate spaces (34), and the two cells (36) of the single pair of adjacent cells (36) are separated from each other and from the adjacent first plate spaces (32) and / or the adjacent second plate spaces (34) by at least one deformable wall portion (38).

12. The brazed flat plate heat exchanger (10) according to claim 11, characterized in that the pairs of adjacent cells (36) are connected to each other through connecting conduits (52), and the connecting conduits (52) are fluidly connected to a single lateral opening (54) obtained in one of the side ends (26, 28) of the heat exchanger plates (12A, 12B, 12C) through at least one of the channels (40).

13. The brazed plate heat exchanger (10) according to claim 12, characterized in that the pairs of adjacent cells (36) and the connecting conduits (52) are filled with an inert gas.

14. The brazed plate heat exchanger (10) according to claim 13, characterized in that at least one probe (56) is connected to the lateral opening (54), and the probe (56) is capable of detecting changes in the pressure and / or temperature of the inert gas.

15. A brazed plate heat exchanger (10) according to any one of claims 1 to 14, comprising one or more fluid collection tanks (58, 60) positioned outside the brazed plate heat exchanger (10) and designed to collect fluid exiting the heat exchanger (10) through at least one channel (40), wherein the fluid collection tanks (58, 60) preferably comprise one or more fluid level sensors (62) and / or one or more overflow discharge lines (64).

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