Plate heat exchanger

Abstract

The application provides a plate heat exchanger, comprising: at least two plates arranged in a stack; each plate is etched on a single side surface to form at least two flow channels, and the flow channels extend along the length direction of the plate; wherein a porous coating is arranged in the flow channels. By arranging the porous coating in the flow channels, the number of vaporization cores on the inner wall of the flow channels can be greatly increased, the superheat degree of the boiling initiation can be reduced, the uniform generation and rapid separation of the micro-bubbles from the wall surface can be promoted, the aggregation and coalescence of the large bubbles can be inhibited, the flow channel blockage and the flow pressure drop increase can be avoided, and thus the boiling heat exchange capacity and the operation stability of the plate heat exchanger can be significantly improved.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and more specifically to a plate heat exchanger. Background Technology

[0002] Plate heat exchangers have advantages such as compact structure, high heat exchange efficiency, and convenient disassembly and maintenance, and are therefore widely used in energy and power, chemical refrigeration, nuclear power heat exchange and other fields.

[0003] The plates of existing plate heat exchangers are mostly formed by etching to create the flow channels. However, the inner walls of the flow channels are mostly smooth. Under boiling heat exchange conditions, the number of vaporization nuclei on the wall surface is small, and the superheat of bubble generation is large. This can easily lead to the formation of large bubbles or even gas locks in the flow channels. This can not only cause flow channel blockage and increase the pressure drop of the medium flow, but also easily cause local dry burning problems, which can significantly reduce the boiling heat exchange stability and overall heat exchange performance of the heat exchanger.

[0004] Based on this, the inventors of this application propose a plate heat exchanger in order to solve one or more of the aforementioned technical problems. Summary of the Invention

[0005] The present invention solves the above-mentioned technical problems through the following technical solution: The present invention provides a plate heat exchanger, comprising: at least two stacked plates; Each of the aforementioned plates has at least two flow channels etched on one side surface, the flow channels extending along the length of the plate; wherein, The flow channel is equipped with a porous coating.

[0006] According to one embodiment of the present invention, the porous coating is formed by high-temperature sintering of metal powder and forms an integrated structure with the plate.

[0007] According to one embodiment of the present invention, the porous coating is formed on the inner wall of the flow channel by 3D printing.

[0008] According to one embodiment of the present invention, the thickness of the porous coating is 0.1 mm to 0.5 mm; The porosity of the porous coating is 25%-50%.

[0009] According to one embodiment of the present invention, the cross-sectional shape of the flow channel along the medium flow direction is an arc shape; The porous coating is applied to the bottom region of the concave arc surface of the flow channel.

[0010] According to one embodiment of the present invention, the cross-sectional shape of the flow channel along the medium flow direction is rectangular; The porous coating is applied to the circumferential sidewalls of the flow channel.

[0011] According to one embodiment of the present invention, the flow channel is any one of a straight flow channel, a Z-shaped flow channel, an S-shaped flow channel, or an airfoil flow channel.

[0012] According to one embodiment of the present invention, a plurality of flow channels are etched on each of the plates, and the center lines of the plurality of flow channels are parallel to each other and equally spaced.

[0013] According to one embodiment of the present invention, the plate is provided with an inlet section and an outlet section at both ends, and both the inlet section and the outlet section are connected to the flow channel.

[0014] According to one embodiment of the present invention, the flow channel includes a first medium channel and a second medium channel, wherein the first medium channel and the second medium channel are arranged at intervals from each other; The first medium channel is for the medium to be cooled to flow through, and the second medium channel is for the coolant to flow through.

[0015] The positive and progressive effects of this invention are as follows: The plate heat exchanger of the present invention, by setting a porous coating in the flow channel, can significantly increase the number of vaporization nuclei on the inner wall of the flow channel, reduce the boiling initiation superheat, promote the uniform generation of micro bubbles and their rapid detachment from the wall surface, inhibit the aggregation and merging of large bubbles, and avoid flow channel blockage and increased flow pressure drop. As a result, the boiling heat transfer capacity and operational stability of the plate heat exchanger can be significantly improved. Attached Figure Description

[0016] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein: Figure 1 This is a partial structural schematic diagram of a plate heat exchanger according to an embodiment of the present invention; Figure 2 for Figure 1 A partial schematic diagram of the bonding between the middle plate and the coating; Figure 3 This is a schematic diagram of the plate structure according to another embodiment of the present invention; Figure 4 This is a schematic diagram of the flow channel arrangement of one embodiment of the plate heat exchanger of the present invention.

[0017] 1. Plate; 11. Import section; 12. Exit section; 2. Flow channel; 21. First medium channel; 22. Second medium channel; 3. Porous coating. Detailed Implementation

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0019] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0020] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0021] Existing plate heat exchangers mostly form flow channels by etching plates, and the inner walls of these channels are generally smooth. Under boiling heat exchange conditions, the number of vaporization nuclei on smooth walls is insufficient, the superheat required for boiling initiation is high, and large bubbles are easily generated and aggregated within the flow channels, leading to gas locks, flow channel blockage, and increased pressure drop of the medium. Simultaneously, bubble retention can easily cause localized dry burning of the wall surface, severely weakening the heat exchange efficiency and operational stability of the plate heat exchanger.

[0022] In view of the above-mentioned shortcomings of the existing technology, this application proposes a plate heat exchanger, specifically including at least two stacked plates 1. Each plate 1 has at least two flow channels 2 etched on one side surface, the flow channels 2 extending along the length direction of the plate 1; wherein, a porous coating 3 is provided in the flow channels 2.

[0023] like Figure 1As shown, the example is a stacked arrangement of three plates 1 (A, B, C). Multiple channels 2 for medium flow are etched on each plate 1 (A, B, C). The number of channels 2 is only for example and is not limited in shape or number.

[0024] In practical applications, the flow channels 2 of plates 1A and 1C can serve as the first medium channel 21 for the flow of coolant. The flow channel 2 of plate 1B can serve as the second medium channel 22 for the flow of the medium to be cooled, through which heat exchange and cooling can be achieved.

[0025] Optionally, the medium to be cooled can be high-temperature steam, and the corresponding coolant can be water. The specific coolant and medium to be cooled can be selected according to actual needs, and no limitation is made here.

[0026] like Figure 1 and Figure 2 As shown, this application provides a porous coating 3 on the inner wall of the smooth flow channel 2, which can significantly increase the number of micro vaporization nuclei on the wall of the flow channel 2, reduce the initial superheat of boiling heat transfer, promote the uniform generation of micro bubbles and their rapid detachment from the wall, suppress the formation of large bubbles and gas plugs from the source, and avoid blockage of the flow channel 2 and increased flow pressure drop.

[0027] Meanwhile, the porous coating 3 has good capillary liquid replenishment capability, which can effectively prevent local dry burning on the heat exchange wall surface, increase the micro heat exchange area, and enhance the fluid disturbance near the wall surface. Overall, it can improve the boiling heat exchange efficiency and operational stability of the plate heat exchanger.

[0028] In one embodiment, the porous coating 3 is formed by high-temperature sintering of metal powder and forms an integrated structure with the plate 1.

[0029] Compared with traditional spraying and bonding methods, the high-temperature sintering method adopted in this application can form a strong metallurgical bond between the porous coating 3 and the plate 1, thereby effectively improving the bonding strength between the porous coating 3 and the plate 1 and avoiding problems such as coating peeling, cracking and detachment in plate heat exchangers under long-term alternating hot and cold conditions.

[0030] Meanwhile, the porous structure formed by sintering metal powder has uniform pores and high overall structural strength, thus possessing the effects of high temperature resistance, media erosion resistance and thermal shock resistance. This ensures that the plate heat exchanger's effects of suppressing large bubble generation, replenishing liquid and strengthening its own structure do not diminish during long-term operation, thereby ensuring the service life and operational reliability of the plate heat exchanger.

[0031] In some other embodiments, the porous coating 3 can also be formed on the inner wall of the flow channel 2 by 3D printing.

[0032] 3D printing has the advantages of high molding precision and strong structural controllability. It can achieve integrated molding of the inner wall of complex irregular flow channel 2 without the need for subsequent secondary processing. It has high molding efficiency and the resulting coating morphology fits the inner wall of flow channel 2 better.

[0033] The porous coating 3, formed by 3D printing, can ensure the uniform distribution of vaporization cores and accurately match the bubble generation pattern, thus better suppressing the generation of large bubbles and improving the heat exchange effect of plate heat exchangers.

[0034] Please continue to refer to Figure 1 and Figure 2 Optionally, the thickness of the porous coating 3 is 0.1mm-0.5mm; the porosity of the porous coating 3 is 25%-50%.

[0035] By limiting the thickness range of the porous coating 3, it is possible to avoid the porous coating 3 becoming too thick and encroaching on the flow cross-section of the flow channel 2, thereby increasing the flow resistance. At the same time, it is also possible to avoid insufficient vaporization nuclei and weak strengthening effect due to the porous coating 3 being too thin.

[0036] By setting a porous coating 3 with a porosity of 25%-50% on the inner wall of the flow channel 2, the porous coating 3 can form a continuous capillary channel, which not only ensures the capillary siphon liquid replenishment capacity and can replenish the medium carried away by boiling phase change in time to avoid local dry burning; but also prevents the structural strength from decreasing due to excessive porosity and easy erosion by the medium, and also avoids the loss of capillary action and vaporization core advantages due to excessively low porosity.

[0037] Please refer to Figure 3 In one embodiment, the cross-sectional shape of the flow channel 2 along the medium flow direction is arc-shaped; the porous coating 3 is applied to the bottom area of ​​the arc concave surface of the flow channel 2.

[0038] Because the bottom of the concave arc surface is a dead zone with the thickest boundary layer, heat easily accumulates, and bubbles are most likely to form, become trapped, and grow. By strategically placing a porous coating 3 at this location, vaporization nuclei can be densely provided in the core area where bubbles initially form, prompting bubbles to form in a small form and detach quickly. Simultaneously, the capillary action of the porous structure continuously replenishes liquid into the gaps within the porous coating 3, effectively inhibiting the aggregation and merging of large bubbles at the bottom of the concave surface, preventing bubble stagnation in this area from forming gas plugs and blocking the flow channel 2.

[0039] Please continue to refer to Figure 1 In some other embodiments, the cross-sectional shape of the flow channel 2 along the medium flow direction is rectangular; the porous coating 3 is applied to the circumferential sidewall of the flow channel 2.

[0040] It should be noted that the low fluid velocity, thick boundary layer, and high superheat of the sidewalls of the rectangular flow channel are the main areas where bubbles preferentially generate, attach, and grow, while the bottom wall is directly scoured by the mainstream medium and does not easily accumulate bubbles.

[0041] Therefore, this application employs a circumferential sidewall arrangement for the rectangular cross-section flow channel 2 to cover areas prone to bubble formation, preventing large bubbles from forming due to localized boiling at single points on the sidewall. Simultaneously, the capillary channels of the porous sidewall structure ensure uniform liquid replenishment, preventing dry burning of the sidewall heat exchange surface. This effectively reduces the probability of bubble adhesion and retention, inhibits bubble coalescence and growth, and reduces medium flow resistance, significantly improving the heat transfer stability of the rectangular cross-section flow channel 2.

[0042] In one embodiment, the flow channel 2 is any one of a straight flow channel 2, a Z-shaped flow channel 2, an S-shaped flow channel 2, or an airfoil flow channel 2. Figure 4 The example used is a Z-shape, but this is not a limitation.

[0043] For the direct-flow channel 2, its flow resistance is low, making it suitable for high-flow-rate conditions. The Z-shaped and S-shaped channels 2 can extend the medium flow path, enhance fluid turbulence, and increase the heat exchange temperature difference, making them suitable for conditions requiring high heat exchange temperature differences. The airfoil channel 2 has a streamlined structure with low flow resistance, making it suitable for high gas-liquid ratio boiling conditions.

[0044] The specific form of flow channel 2 can be selected based on actual working conditions, and no limitation is made here.

[0045] Please continue to refer to Figure 4 Multiple flow channels 2 are etched on each plate 1, and the center lines of the multiple flow channels 2 are parallel to each other and equally spaced.

[0046] This application arranges multiple parallel flow channels 2 at equal intervals on a single plate 1, which makes the flow channels 2 on the surface of the plate 1 well-distributed and the medium flow uniform. The medium velocity, flow rate and heat exchange conditions in each flow channel 2 are kept consistent, avoiding uneven heat exchange and local overheating caused by excessive or insufficient flow rate in a single flow channel 2.

[0047] Moreover, the parallel and equally spaced layout facilitates the overall etching process of plate 1 and the standardization of molds, thereby reducing the processing cost of plate 1. At the same time, after the plates 1 are stacked, the hot and cold flow channels 2 are arranged in a regular manner, with high heat exchange area utilization and uniform and stable heat exchange. Combined with the porous coating 3 on the inner wall of the flow channel 2, the boiling heat exchange performance of each area of ​​the overall heat exchanger can be balanced, without any local heat exchange shortcomings.

[0048] The plate 1 has an inlet section 11 and an outlet section 12 at both ends, and both the inlet section 11 and the outlet section 12 are connected to the flow channel 2.

[0049] By setting an inlet section 11 and an outlet section 12 at both ends of the plate 1 that are connected to the flow channel 2, the medium can be smoothly divided and merged, so that the medium is evenly introduced into each flow channel 2, and smoothly merged and flowed out after heat exchange, avoiding turbulence, deflection and eddies when the medium enters and exits, and reducing the local pressure drop at the inlet and outlet.

[0050] Meanwhile, the inlet section 11 and outlet section 12 can guide and stabilize the flow of the medium, ensuring a balanced distribution of the medium in each flow channel 2, making the boiling conditions in the flow channel 2 stable and controllable. Combined with the enhanced heat exchange structure of the porous coating 3, it can maintain the stability of the flow rate and heat exchange parameters of the entire plate heat exchanger system, and improve the overall stability and heat exchange consistency of the machine.

[0051] In summary, the plate heat exchanger proposed in this application has at least the following beneficial effects: First, it effectively solves the problems of insufficient vaporization nuclei and high boiling initiation superheat in traditional smooth flow channels 2. The porous coating 3 on the inner wall of flow channel 2 can provide a large number of uniformly distributed vaporization nuclei, which promotes the medium to be cooled to be generated quickly in the form of micro bubbles and detach from the wall surface. It inhibits the aggregation and merging of large bubbles from the source, avoids the formation of gas plugs to block flow channel 2, ensures smooth medium flow, and reduces flow pressure drop.

[0052] Second, it can target high-bubble areas according to different flow channel cross-sectional shapes such as arc and rectangle, accurately matching the bubble formation pattern to maximize the functions of bubble suppression and anti-clogging. At the same time, relying on the capillary replenishment capability of the porous structure, it continuously replenishes the medium carried away by boiling phase change, effectively avoiding local dry burning of the wall surface and improving the heat exchange stability of the plate heat exchanger.

[0053] Third, the porous coating 3 can be formed by high-temperature sintering or 3D printing, forming a firm bond with the plate 1. It has high structural strength, is resistant to erosion and thermal shock, and can maintain the pore structure and vaporization core function for a long time. This avoids the problem of coating peeling off under long-term alternating hot and cold conditions and extends the service life of the plate heat exchanger.

[0054] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0055] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0056] Flowcharts are used in this application to illustrate the operations performed by the system according to embodiments of this application. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, various steps can be processed in reverse order or simultaneously. Furthermore, other operations may be added to these processes, or one or more steps may be removed from these processes.

[0057] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0058] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of scope in some embodiments of this application are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0059] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the essential spirit of this application will fall within the scope of the claims of this application.

Claims

1. A plate heat exchanger, characterized in that, include: At least two stacked panels; Each of the aforementioned plates has at least two flow channels etched on one side surface, the flow channels extending along the length of the plate; wherein, The flow channel is equipped with a porous coating.

2. The plate heat exchanger according to claim 1, characterized in that, The porous coating is formed by high-temperature sintering of metal powder and is integrated with the plate to form an integral structure.

3. The plate heat exchanger according to claim 1, characterized in that, The porous coating is formed on the inner wall of the flow channel by 3D printing.

4. The plate heat exchanger according to claim 1, characterized in that, The thickness of the porous coating is 0.1mm-0.5mm; The porosity of the porous coating is 25%-50%.

5. The plate heat exchanger according to claim 1, characterized in that, The cross-sectional shape of the flow channel along the medium flow direction is arc-shaped; The porous coating is applied to the bottom region of the concave arc surface of the flow channel.

6. The plate heat exchanger according to claim 1, characterized in that, The cross-sectional shape of the flow channel along the medium flow direction is rectangular; The porous coating is applied to the circumferential sidewalls of the flow channel.

7. The plate heat exchanger according to claim 1, characterized in that, The flow channel is any one of a straight flow channel, a Z-shaped flow channel, an S-shaped flow channel, or an airfoil flow channel.

8. The plate heat exchanger according to claim 1, characterized in that, Multiple flow channels are etched on each of the aforementioned plates, with the center lines of the multiple flow channels being parallel to each other and equally spaced.

9. The plate heat exchanger according to claim 1, characterized in that, The plate has an inlet section and an outlet section at both ends, and both the inlet section and the outlet section are connected to the flow channel.

10. The plate heat exchanger according to claim 1, characterized in that, The flow channel includes a first medium channel and a second medium channel, which are arranged at intervals from each other. The first medium channel is for the medium to be cooled to flow through, and the second medium channel is for the coolant to flow through.

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