Printed circuit board type flue gas heat exchanger and its preparation method

Abstract

This invention discloses a printed circuit board type flue gas heat exchanger and its manufacturing method. The heat exchanger includes a heat exchanger core, which comprises a flue gas side plate structure and a cold fluid plate. The flue gas side plate structure and the cold fluid plate are stacked alternately, and cold fluid channels are machined within the cold fluid plate. The flue gas side plate structure includes a flue gas side upper cover plate, a flue gas side middle plate, and a flue gas side lower cover plate. Upper and lower notches are machined on opposite surfaces of the upper and lower cover plates, respectively. Flow channels are formed on the flue gas side middle plate. The upper notch, flow channels, and lower notch constitute a complete flue gas flow channel, and multiple turbulent fluids are pre-machined within the flow channels of the flue gas side middle plate. This invention sets turbulent fluids in the flue gas flow channel to ensure high-intensity heat transfer on the flue gas side. Furthermore, by adding the flue gas side middle plate, a large number of turbulent fluids can be formed on the flue gas side middle plate in one step, and then the flue gas side middle plate is welded as a whole into the flue gas heat exchanger, which is simple to manufacture and low in cost.

Description

Technical Field

[0001] This invention relates to the field of thermal energy technology, specifically to a printed circuit board type flue gas heat exchanger and its preparation method. Background Technology

[0002] The exhaust gas from internal combustion engines is mainly produced by fuel combustion. It is at a high temperature and contains pollutants such as sulfides and dust. To ensure all this exhaust gas is released into the atmosphere, it must be treated. During this treatment process, flue gas heat exchangers can be used to recover waste heat from the high-temperature flue gas, achieving thermal energy reuse. Therefore, flue gas heat exchangers are widely used in industrial waste heat recovery projects and are a key component of the waste heat recovery cycle system, responsible for absorbing heat from the exhaust gas from the internal combustion engine. Small, lightweight heat exchangers are the primary consideration for the application of waste heat recovery in internal combustion engines. However, traditional heat exchangers and traditional heat exchange enhancement methods suffer from low heat exchange efficiency, resulting in excessively large and heavy flue gas heat exchangers.

[0003] In related technologies, Chinese invention patent document CN109899823A discloses a micro-eccentric oscillating flue gas turbulence device and a method for enhancing heat exchange in flue pipes. This turbulence device includes a micro-eccentrically positioned turbulence plate that can rotate along a positioning shaft, and a positioning shaft that fixes the turbulence plate in the flue pipe. The rotating turbulence plate agitates the flue gas in the flue pipe to reduce the boundary layer thermal resistance of the inner wall of the flue pipe and / or generate local turbulence in the flue pipe. The positioning shaft is fixed inside the flue pipe by expansion, welding, threading, or grooving. This solution requires fixing each turbulence structure to the flue pipe individually using expansion, welding, threading, or grooving, which is difficult and costly to manufacture. Furthermore, the large size of the flue pipe results in an excessively large volume and weight of the flue gas heat exchanger.

[0004] Printed circuit board heat exchangers (PCHEs) are highly efficient and compact heat exchange devices with advantages such as large heat transfer area per unit volume and safe and reliable operation under high temperature and high pressure conditions. They can meet the requirements for miniaturization and weight reduction of flue gas heat exchangers. Related technologies already include solutions using printed circuit board flue gas heat exchangers, such as those described in patent documents with publication numbers CN113670098A and CN112097552A; however, these solutions do not incorporate turbulence structures in the flue gas flow path, resulting in low heat exchange efficiency on the flue gas side. Summary of the Invention

[0005] The technical problem to be solved by the present invention is how to provide a flue gas heat exchanger that is easy to process, low in cost, and can guarantee highly enhanced heat exchange on the flue gas side.

[0006] The present invention solves the above-mentioned technical problems through the following technical means:

[0007] This invention proposes a printed circuit board type flue gas heat exchanger, the heat exchanger comprising a micron-sized printed circuit board type heat exchanger core, the heat exchanger core comprising a flue gas side plate structure and a cold fluid plate, the flue gas side plate structure and the cold fluid plate being stacked alternately, and the cold fluid plate having a cold fluid flow channel processed inside;

[0008] The flue gas side plate structure includes a flue gas side upper cover plate, a flue gas side middle plate, and a flue gas side lower cover plate. The upper and lower covers plate are respectively machined with an upper recess and a lower recess on their opposite surfaces. A flow channel is opened on the flue gas side middle plate. The upper recess, the flow channel, and the lower recess constitute a complete flue gas flow channel. Multiple turbulent fluids are pre-machined in the flow channel of the flue gas side middle plate.

[0009] This invention incorporates a turbulent flow path in the flue gas flow channel to ensure highly enhanced heat transfer on the flue gas side. Furthermore, by adding an intermediate plate on the flue gas side, a large number of turbulent flow structures can be fabricated on the intermediate plate in one go, and then the intermediate plate is welded as a whole into the flue gas heat exchanger, which is simple to process and low in cost. In addition, the flue gas flow channel is formed by a combination of three layers of plates. This multi-layer structure not only facilitates the addition of micro-turbulent flow structures, but also effectively increases the flue gas flow area and reduces the flue gas pressure drop.

[0010] Furthermore, the flue gas side plate structure is provided with a plurality of flue gas flow channels, and the cold fluid plate is provided with a plurality of cold fluid flow channels. The plurality of flue gas flow channels and the plurality of cold fluid flow channels are arranged in a periodic staggered combination in the stacking direction.

[0011] Furthermore, the flue gas side intermediate plate is provided with the turbulent fluid obtained by chemical corrosion or mechanical processing, and the turbulent fluid is determined in advance by numerical simulation calculation.

[0012] Furthermore, the heat exchanger core adopts a micron-level printed circuit board type heat exchanger core.

[0013] Furthermore, the turbulent fluid can be rectangular, circular, airfoil-shaped, or triangular.

[0014] Furthermore, the distance between adjacent turbulent fluids ranges from 2 mm to 40 mm.

[0015] Furthermore, the horizontal tilt angle of the turbulent fluid is between 0 and 45°.

[0016] Furthermore, the thickness of the turbulent fluid is between 150 μm and 750 μm, and the length of the turbulent fluid is between 1 mm and 2 mm.

[0017] Furthermore, the hydraulic diameter of the flue gas flow channel orifice is 0.5mm to 4mm, and the hydraulic diameter of the cold fluid flow channel orifice is 0.5mm to 3mm.

[0018] Furthermore, the flue gas side upper cover plate, the flue gas side middle plate, the flue gas side lower cover plate, and the cold fluid plate are all made of corrosion-resistant materials, and the plates are welded together by high-temperature diffusion welding.

[0019] Furthermore, this invention also proposes a method for preparing a printed circuit board flue gas heat exchanger, the method comprising:

[0020] Based on the parameters of the turbulent fluid, the turbulent fluid is processed on the flue gas side intermediate plate by chemical etching or mechanical processing.

[0021] The flue gas side upper cover plate, the flue gas side lower cover plate, and the cold fluid plate are processed, wherein the cold fluid plate is processed with a cold fluid flow channel;

[0022] The upper cover plate on the flue gas side, the middle plate on the flue gas side, and the lower cover plate on the flue gas side are subjected to high-temperature diffusion welding to form a flue gas side plate structure with a flue gas flow channel.

[0023] The flue gas side plate structure and the cold fluid plate are alternately stacked and welded with high diffusion to obtain a flue gas heat exchanger.

[0024] Furthermore, the method also includes determining the optimal parameters of the turbulent fluid within the flue gas duct based on numerical simulation calculations, specifically:

[0025] Determine multiple combinations of parameters for the turbulent fluid, each of which includes location, quantity, shape, and size;

[0026] Based on the parameters of the turbulent fluid and the flue gas flow path, the flue gas flow path of the flue gas heat exchanger is modeled using Ansys Fluent modeling software, and the boundary conditions are determined.

[0027] The model of the flue gas flow path is discretized and meshed to obtain a high-quality mesh model;

[0028] Based on the control equations, the flow and heat transfer effects of the flue gas duct model under various combinations of parameters are determined.

[0029] By comparing the flow and heat transfer effects of the flue gas duct model under different parameter combinations, the optimal parameter combination of the turbulent fluid is determined.

[0030] Furthermore, the governing equations are expressed as follows:

[0031] Continuity equation:

[0032]

[0033] Turbulence equations:

[0034]

[0035] Energy equation:

[0036]

[0037] Heat conduction equation:

[0038]

[0039] In the formula: u i ρ is the velocity vector; x is the fluid density; i u represents the velocity component along the x-axis. j V is the velocity component along the y-axis; P is pressure; g is the gravitational factor; μt is molecular viscosity; μs is turbulent velocity; E is energy; K eff τ is the effective conductivity; T is the temperature; τ is the effective conductivity. ij S is the time factor; h For turbulent dissipation, λ is the turbulent thermal conductivity. For temperature gradient.

[0040] Furthermore, the upper cover plate and the lower cover plate on the flue gas side are respectively machined with an upper recess and a lower recess. The upper cover plate, the intermediate plate on the flue gas side, and the lower cover plate on the flue gas side are subjected to high-temperature diffusion welding to form a flue gas side plate structure with a flue gas flow channel, including:

[0041] The upper recess of the flue gas side upper cover plate is opposite to the lower recess of the flue gas side lower cover plate, and the flue gas side intermediate plate is located between the flue gas side upper cover plate and the flue gas side lower cover plate and is subjected to high-temperature diffusion welding to form the flue gas side plate structure. The upper recess, the flue gas side intermediate plate and the lower recess constitute a complete flue gas flow channel.

[0042] The advantages of the present invention are:

[0043] (1) The present invention provides a turbulent fluid in the flue gas flow channel, which can ensure high heat exchange on the flue gas side; and by adding the flue gas side intermediate plate, a large number of turbulent fluid structures can be formed on the flue gas side intermediate plate in one go, and then the flue gas side intermediate plate is welded into the flue gas heat exchanger as a whole, which is simple to process and low in cost; in addition, the flue gas flow channel is formed by the combination of three layers of plates. This multi-layer structure not only facilitates the addition of micro turbulent structures, but also effectively increases the flue gas flow area and reduces the flue gas pressure drop.

[0044] (2) The optimal position and size of the turbulent fluid can be calculated in advance through numerical simulation, so that the flue gas channel has the best heat transfer flow resistance performance.

[0045] (3) The core of the flue gas heat exchanger adopts a micron-level printed circuit board, which can meet the requirements of small size and lightweight.

[0046] (4) The heat exchanger core is made of corrosion-resistant materials such as stainless steel to improve the corrosion resistance of the heat exchanger.

[0047] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the printed circuit board type flue gas heat exchanger in the first embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the single-channel structure on the flue gas side in the first embodiment of the present invention, wherein (a) is a schematic diagram of the flow of flue gas in the flue gas channel after it flows into the core, and (b) is a cross-sectional view of (a);

[0050] Figure 3 This is a comparison chart of heat transfer performance with and without micro-turbulent fluid in the first embodiment of the present invention;

[0051] Figure 4 This is a schematic flowchart of the preparation method of the printed circuit board type flue gas heat exchanger in the second embodiment of the present invention.

[0052] In the picture:

[0053] 1-Upper cover plate on the flue gas side; 2-Intermediate plate on the flue gas side; 3-Lower cover plate on the flue gas side; 4-Cold fluid plate; 5-Cold fluid channel; 6-Flue gas channel; 7-Turbulent fluid. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0055] like Figure 1 As shown, the first embodiment of the present invention proposes a printed circuit board type flue gas heat exchanger, including a heat exchanger core, the heat exchanger core including a flue gas side plate structure and a cold fluid plate 4, the flue gas side plate structure and the cold fluid plate 4 are stacked alternately, and a cold fluid channel 5 is processed in the cold fluid plate 4;

[0056] The flue gas side plate structure includes a flue gas side upper cover plate 1, a flue gas side middle plate 2, and a flue gas side lower cover plate 3. The flue gas side upper cover plate 1 and the flue gas side lower cover plate 3 are respectively machined with an upper notch and a lower notch on their opposite surfaces. A flow channel is opened on the flue gas side middle plate 2. The upper notch, the flow channel, and the lower notch constitute a complete flue gas flow channel 6. Multiple turbulent fluids 7 are pre-machined in the flow channel of the flue gas side middle plate 2.

[0057] In this embodiment, by providing a turbulent flow 7 in the flue gas flow channel 6, high-intensity heat transfer on the flue gas side can be ensured. Moreover, by adding the flue gas side intermediate plate 2, a large number of turbulent flow 7 structures can be formed on the flue gas side intermediate plate 2 in one go, and then the flue gas side intermediate plate 2 can be welded into the flue gas heat exchanger as a whole, which is simple to process and low in cost. In addition, the flue gas flow channel 6 is formed by combining three layers of plates. This multi-layer structure not only facilitates the addition of micro turbulent flow structures, but also effectively increases the flue gas flow area and reduces the flue gas pressure drop.

[0058] In one embodiment, the flue gas side plate structure is provided with a plurality of flue gas flow channels 6, and the cold fluid plate 4 is provided with a plurality of cold fluid flow channels 5. The plurality of flue gas flow channels 6 and the plurality of cold fluid flow channels 5 are arranged in a periodic staggered combination in the stacking direction.

[0059] It should be noted that multiple upper recesses are equally spaced on the flue gas side upper cover plate 1, and multiple lower recesses are equally spaced on the flue gas side lower cover plate 3. The positions of the upper and lower recesses correspond and the number is the same, which can be about 50. Multiple flow channels are opened on the flue gas side middle plate 2. The positions of the flow channels correspond to the positions of the upper and lower recesses and the number is the same. Multiple micro-fluid-flow structures are processed in each flow channel. By combining and welding the flue gas side upper cover plate 1, the flue gas side middle plate 2, and the flue gas side lower cover plate 3, a flue gas side plate structure with a certain number of flue gas flow channels 6 is formed. Cold fluid channels 5 are processed in the cold fluid plate 4. After the flue gas side plate structure and the cold fluid plate 4 are alternately stacked and welded, the multiple flue gas flow channels 6 and the multiple cold fluid flow channels 5 are periodically staggered and arranged in the stacking direction.

[0060] Furthermore, the cross-sectional shapes of the upper and lower recesses include, but are not limited to, rectangles, arcs, trapezoids, etc., and the shapes of the upper and lower recesses are symmetrically arranged.

[0061] It should be noted that, according to numerical simulation calculations, the performance of flue gas duct 6 is better when the cross-sectional shape of the upper and lower notches is rectangular.

[0062] In one embodiment, the flue gas side intermediate plate 2 is provided with the turbulent fluid 7 obtained by chemical corrosion or mechanical processing, and the turbulent fluid 7 is determined in advance by numerical simulation calculation.

[0063] It should be noted that, in this embodiment, by adding the flue gas side intermediate plate 2, a large number of turbulent fluids 7 can be formed on the intermediate plate at one time, and the intermediate plate can be welded into the flue gas heat exchanger as a whole. The processing is simple and greatly reduces the cost of the heat exchanger reinforcement structure.

[0064] Furthermore, in this embodiment, the optimal arrangement position and parameters of the turbulent fluid 7 structure are determined by performing numerical simulation calculations in advance, and the structure is pre-processed on the intermediate plate, which enables the flue gas duct 6 to have the best heat transfer flow resistance performance.

[0065] In one embodiment, the heat exchanger core is a micron-sized printed circuit board type heat exchanger core.

[0066] In this embodiment, the core of the flue gas heat exchanger adopts a micron-level printed circuit board, which can meet the requirements of small size and lightweight.

[0067] In one embodiment, the turbulent fluid 7 may take the shape of, but is not limited to, rectangle, circle, airfoil or triangle.

[0068] It should be noted that, based on prior numerical simulation calculations, this embodiment determined that the turbulence structure performs best when the turbulence fluid 7 is rectangular.

[0069] In one embodiment, the distance between adjacent disturbing fluids 7 ranges from 2 mm to 40 mm.

[0070] In this embodiment, simulation shows that when the distance between adjacent turbulent fluids 7 is set between 2mm and 40mm, the turbulence structure performs better. The distance between each turbulent fluid 7 can be the same or different, and those skilled in the art can set it according to actual needs.

[0071] In one embodiment, the horizontal tilt angle of the turbulent fluid 7 is between 0 and 45°.

[0072] It should be noted that those skilled in the art can adjust the tilt angle of the spoiler structure for different engine operating conditions.

[0073] In one embodiment, the thickness of the turbulent fluid 7 is between 150 μm and 750 μm, and the length of the turbulent fluid 7 is between 1 mm and 2 mm.

[0074] It should be noted that numerical simulation calculations have determined that the turbulent fluid 7 structure of this size has the best heat transfer and flow resistance performance.

[0075] In one embodiment, the hydraulic diameter of the flue gas flow channel 6 orifice is 0.5mm to 4mm, and the hydraulic diameter of the cold fluid flow channel 5 orifice is 0.5mm to 3mm.

[0076] In one embodiment, the flue gas side upper cover plate 1, the flue gas side middle plate 2, the flue gas side lower cover plate 3, and the cold fluid plate 4 are all made of corrosion-resistant materials, and the plates are welded together by high-temperature diffusion welding.

[0077] In this embodiment, the heat exchanger core is made of corrosion-resistant materials such as stainless steel to improve the corrosion resistance of the heat exchanger.

[0078] It should be noted that high-temperature fluids, such as flue gas, flow into the core and then into the flue gas flow channel 6 (e.g., Figure 2 (a) shown). Through the sectional view (as shown in the image). Figure 2 As shown in (b), the specific location and size of the micron-sized turbulent fluid 7 within the flow channel can be observed. The micron-sized turbulent fluid 7 is positioned in the middle of the flow channel. By using a centrally machined intermediate plate, a large number of micron-sized turbulent fluids 7 can be obtained. During flue gas flow, the flue gas collides with and passes over the micron-sized turbulent structure. The micron-sized turbulent structure increases the heat transfer area and disrupts the fluid thermal boundary layer, enhancing fluid turbulence and strengthening heat transfer. Simulation calculations show that the heat transfer performance of the flow channel with the micron-sized turbulent structure is 43% higher than that of the traditional flow channel. Figure 3 As shown.

[0079] In addition, such as Figure 4 As shown, the second embodiment of the present invention also proposes a method for preparing a printed circuit board flue gas heat exchanger, the method comprising:

[0080] S10. Based on the parameters of the turbulent fluid, the turbulent fluid is processed on the flue gas side intermediate plate by chemical etching or mechanical processing.

[0081] S20. Process the flue gas side upper cover plate, the flue gas side lower cover plate and the cold fluid plate, wherein the cold fluid plate is processed with a cold fluid flow channel.

[0082] S30. The upper cover plate on the flue gas side, the middle plate on the flue gas side, and the lower cover plate on the flue gas side are subjected to high-temperature diffusion welding to form a flue gas side plate structure with a flue gas flow channel.

[0083] S40. The flue gas side plate structure and the cold fluid plate are alternately stacked and welded with high diffusion to obtain a flue gas heat exchanger.

[0084] In this embodiment, a large number of turbulent flow structures are fabricated on the intermediate plate in one go according to the parameters of the turbulent flow, and then welded to the flue gas exchanger. The fabrication process is simple and low-cost, and it can give the flue gas flow channel optimal heat transfer and flow resistance performance. In addition, the flue gas flow channel is formed by combining three layers of plates. This multi-layer structure not only facilitates the addition of micro-turbulent flow structures, but also effectively increases the flue gas flow area and reduces the flue gas pressure drop.

[0085] In one embodiment, the method further includes:

[0086] Determine multiple combinations of parameters for the turbulent fluid, each of which includes location, quantity, shape, and size;

[0087] Based on the parameters of the turbulent fluid and the flue gas flow path, the flue gas flow path of the flue gas heat exchanger is modeled using Ansys Fluent modeling software, and the boundary conditions are determined.

[0088] The model of the flue gas flow path is discretized and meshed to obtain high-quality meshing results;

[0089] Based on the control equations, the flow and heat transfer effects of the flue gas duct model under various combinations of parameters are determined.

[0090] By comparing the flow and heat transfer effects of the flue gas duct model under different parameter combinations, the optimal parameter combination of the turbulent fluid is determined.

[0091] This embodiment determines the optimal parameters of the turbulent fluid through numerical simulation calculation, and processes a large number of turbulent fluids on the intermediate plate according to the optimal parameters. The intermediate plate is then welded to the flue gas heat exchanger, which enables the flue gas flow channel to have the best heat transfer flow resistance performance.

[0092] In one embodiment, the governing equation is expressed as:

[0093] Continuity equation:

[0094]

[0095] Turbulence equations:

[0096]

[0097] Energy equation:

[0098]

[0099] Heat conduction equation:

[0100]

[0101] In the formula: u i ρ is the velocity vector; x is the fluid density; i u represents the velocity component along the x-axis. j V is the velocity component along the y-axis; P is pressure; g is the gravitational factor; μt is molecular viscosity; μs is turbulent velocity; E is energy; K eff τ is the effective conductivity; T is the temperature; τ is the effective conductivity. ij S is the time factor; h For turbulent dissipation, λ is the turbulent thermal conductivity. For temperature gradient.

[0102] In one embodiment, the upper cover plate and the lower cover plate on the flue gas side are respectively machined with an upper recess and a lower recess. The upper cover plate, the intermediate plate on the flue gas side, and the lower cover plate on the flue gas side are high-temperature diffusion welded to form a flue gas side plate structure with a flue gas flow channel, including:

[0103] The upper recess of the flue gas side upper cover plate is opposite to the lower recess of the flue gas side lower cover plate, and the flue gas side intermediate plate is located between the flue gas side upper cover plate and the flue gas side lower cover plate and is subjected to high-temperature diffusion welding to form the flue gas side plate structure. The upper recess, the flue gas side intermediate plate and the lower recess constitute a complete flue gas flow channel.

[0104] It should be noted that the upper recess on the flue gas side upper cover plate, the lower recess on the flue gas side lower cover plate, and the flow channels opened on the flue gas side middle plate are in the same position and have the same number. The upper recess, the flow channels on the flue gas side middle plate, and the lower recess constitute a complete flue gas flow channel. Multiple cold fluid channels are processed inside the cold fluid plate. The flue gas side plate structure and the cold fluid plate are stacked and welded alternately. Multiple flue gas flow channels and multiple cold fluid flow channels are periodically staggered and arranged in the stacking direction to realize the recovery of waste heat from high-temperature flue gas.

[0105] The printed circuit board flue gas heat exchanger prepared in this embodiment can ensure high-intensity heat exchange on the flue gas side, as well as simple processing and low processing cost. Moreover, the heat exchanger core adopts a micron-level printed circuit board, which is of great significance for energy saving and emission reduction of internal combustion engines and the miniaturization and integration of internal combustion engine waste heat recovery systems.

[0106] It should be understood that although this embodiment is described using a waste heat recovery flue gas heat exchanger for internal combustion engines, those skilled in the art will understand that the micron-level turbulence-enhanced heat exchanger according to the present invention is also applicable to other working media (e.g., high-temperature, high-pressure combustion gases). Furthermore, although the flue gas heat exchanger of the present invention is described above using a transcritical cycle system as an example, those skilled in the art will understand that the micron-level turbulence-enhanced heat exchanger of the present invention can also be used in other thermodynamic cycle systems, such as Brayton cycle systems.

[0107] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0108] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0109] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a printed circuit board flue gas heat exchanger, characterized in that, The flue gas heat exchanger includes a heat exchanger core, which comprises a flue gas side plate structure and a cold fluid plate. The flue gas side plate structure and the cold fluid plate are stacked alternately, and a cold fluid channel is machined within the cold fluid plate. The flue gas side plate structure includes a flue gas side upper cover plate, a flue gas side middle plate, and a flue gas side lower cover plate. An upper notch and a lower notch are machined on opposite surfaces of the flue gas side upper cover plate and the flue gas side middle plate, respectively. A flow channel is formed on the flue gas side middle plate. The upper notch, the flow channel, and the lower notch constitute a complete flue gas flow channel. A turbulent fluid obtained by chemical corrosion or mechanical processing is disposed within the flow channel on the flue gas side middle plate. The turbulent fluid is a micron-level turbulent fluid determined in advance by numerical simulation calculation. The method includes: Based on the parameters of the turbulent fluid, the turbulent fluid is processed on the flue gas side intermediate plate by chemical etching or mechanical processing. The flue gas side upper cover plate, the flue gas side lower cover plate, and the cold fluid plate are processed, wherein the cold fluid plate is processed with a cold fluid flow channel; The upper cover plate on the flue gas side, the middle plate on the flue gas side, and the lower cover plate on the flue gas side are subjected to high-temperature diffusion welding to form a flue gas side plate structure with a flue gas flow channel. The flue gas side plate structure and the cold fluid plate are alternately stacked and welded with high diffusion to obtain a flue gas heat exchanger. Among them, the optimal parameters of the turbulent fluid in the flue gas duct were determined based on numerical simulation calculations, specifically as follows: Determine multiple combinations of parameters for the turbulent fluid, each of which includes location, quantity, shape, and size; Based on the parameters of the turbulent fluid and the flue gas flow path, the flue gas flow path of the flue gas heat exchanger is modeled using Ansys Fluent modeling software, and the boundary conditions are determined. The model of the flue gas flow path is discretized and meshed to obtain the meshed result; Based on the governing equations, the flow and heat transfer effects of the flue gas duct model under various parameter combinations are determined, wherein the governing equations are expressed as: Continuity equation: Turbulence equations: Energy equation: Heat conduction equation: In the formula: u i ρ is the velocity vector; x is the fluid density; i u represents the velocity component along the x-axis. j V is the velocity component along the y-axis; P is pressure; g is the gravitational factor; μt is molecular viscosity; μs is turbulent velocity; E is energy; K eff τ is the effective conductivity; T is the temperature; τ is the effective conductivity. ij S is the time factor; h For turbulent dissipation, λ is the turbulent thermal conductivity. For temperature gradient; By comparing the flow and heat transfer effects of the flue gas duct model under different parameter combinations, the optimal parameter combination of the turbulent fluid is determined.

2. The method for preparing a printed circuit board flue gas heat exchanger as described in claim 1, characterized in that, The upper cover plate, the middle plate, and the lower cover plate on the flue gas side are subjected to high-temperature diffusion welding to form a flue gas side plate structure with a flue gas flow channel, including: The upper recess of the flue gas side upper cover plate is opposite to the lower recess of the flue gas side lower cover plate, and the flue gas side intermediate plate is located between the flue gas side upper cover plate and the flue gas side lower cover plate and is subjected to high-temperature diffusion welding to form the flue gas side plate structure. The upper recess, the flue gas side intermediate plate and the lower recess constitute a complete flue gas flow channel.

3. The method for preparing a printed circuit board flue gas heat exchanger as described in claim 1, characterized in that, The flue gas side plate structure has multiple flue gas flow channels, and the cold fluid plate has multiple cold fluid flow channels. The multiple flue gas flow channels and the multiple cold fluid flow channels are periodically and alternately arranged in the stacking direction.

4. The method for preparing a printed circuit board flue gas heat exchanger as described in claim 1, characterized in that, The heat exchanger core adopts a micron-level printed circuit board type heat exchanger core.

5. The method for preparing a printed circuit board flue gas heat exchanger as described in claim 1, characterized in that, The turbulent fluid can be rectangular, circular, airfoil-shaped, or triangular.

6. The method for preparing a printed circuit board flue gas heat exchanger as described in claim 1, characterized in that, The distance between adjacent disturbing fluids ranges from 2 mm to 40 mm.

7. The method for preparing a printed circuit board flue gas heat exchanger as described in claim 1, characterized in that, The horizontal tilt angle of the turbulent fluid is between 0 and 45°.

8. The method for preparing a printed circuit board flue gas heat exchanger as described in claim 1, characterized in that, The thickness of the turbulent fluid is between 150 μm and 750 μm, and the length of the turbulent fluid is between 1 mm and 2 mm.

9. The method for preparing a printed circuit board flue gas heat exchanger as described in claim 1, characterized in that, The hydraulic diameter of the flue gas flow channel orifice is 0.5mm to 4mm, and the hydraulic diameter of the cold fluid flow channel orifice is 0.5mm to 3mm.

10. The method for preparing a printed circuit board flue gas heat exchanger as described in claim 1, characterized in that, The flue gas side upper cover plate, the flue gas side middle plate, the flue gas side lower cover plate, and the cold fluid plate are all made of corrosion-resistant materials.

Images