Flow equalizing structure in seal head of printed circuit board type heat exchanger

Abstract

The invention discloses a flow equalizing structure in a seal head of a printed circuit board type heat exchanger. Comprising a fluid inlet (1), a crescent flow channel a (2) and a crescent flow channel b (3) are symmetrically distributed on the two sides of the fluid inlet (1), the crescent flow channel a and the crescent flow channel b are symmetrically connected with the arc-shaped top of a semi-oval cavity (4), the middle of the bottom of the semi-oval cavity (4) is connected with a core front cavity (6) through a divergent cavity outlet (5), and a triangular shunt array (7) is arranged in the core front cavity (6). The problem that the flow of part of the flow channels in the core body is always too large or too small is solved, and therefore the heat exchange effect of the heat exchanger is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flow heat transfer, in particular to a flow uniformization structure in a printed circuit board heat exchanger head. BACKGROUND

[0002] As a kind of heat exchange equipment with high integration and superior performance, printed circuit board heat exchanger (PCHE) shows wide adaptability in application scenarios with strict requirements for thermal management due to its compact size and high heat exchange density. Its interior is composed of a large number of micro-channels, and cold and hot fluids flow in these channels in opposite or cross directions, thereby realizing efficient heat exchange in limited space. The micro-channel structure not only increases the heat transfer area, but also has the characteristics of high pressure resistance and high temperature resistance, so it is widely favored in the fields of nuclear energy, navigation and aviation. The manufacturing process of PCHE uses etching technology to etch the channel pattern on the metal plate, and then forms the core body through multi-layer diffusion welding. At the upstream and downstream ends of this structure, a head chamber is usually welded for fluid introduction and collection. However, the flow behavior inside the general PCHE head has not been concerned, and since the cross-sectional area of the inlet and outlet pipes is much smaller than that of the head body, the fluid has not been fully developed before entering the heat exchange core, resulting in the flow being concentrated in the channels close to the inlet pipe, while the flow is sparse away from the inlet pipe. The problem of uneven flow caused by this affects the uniformity of the heat exchange process and reduces the heat exchange effect of PCHE.

[0003] The prior art relies on designing a plate-shaped flow guide or flow uniformization structure at the PCHE head, examples of which can be found in many prior art, including Chinese patent No. CN112146485A (Xiao Gang), Chinese patent No. CN114166047A (Xiao Yi), Chinese patent No. CN208952771U (Yang Yu), Chinese patent No. CN108180779A (Guo Jiangfeng), and Chinese patent No. CN105043144A (Wang Qiwang). However, this structure is very limited to specific inlet velocity conditions, and when the inlet flow rate is large and the size of the core body is larger than the inlet of the head, it is still not possible to achieve uniform flow rate at the inlet of the core body. SUMMARY

[0004] The purpose of the present application is to provide a flow uniformization structure in a printed circuit board heat exchanger head. The present application avoids the problem that the flow rate in the core body is always large or small, thereby improving the heat exchange effect of the heat exchanger.

[0005] Technical solution. A flow equalization structure in a printed circuit board heat exchanger head, comprising a fluid inlet, symmetrical crescent-shaped flow channels a and b distributed on both sides of the fluid inlet, the crescent-shaped flow channels a and b are symmetrically connected with the arc-shaped top of the semi-elliptical cavity, the gradually expanding cavity outlet in the middle of the bottom of the semi-elliptical cavity is connected with the front cavity of the core body, and a triangular flow distribution array is arranged in the front cavity of the core body.

[0006] In the aforementioned flow equalization structure in the printed circuit board heat exchanger head, the outer boundary of each crescent-shaped flow channel is a continuous circular arc, and the inner boundary is an inner arc line with a large curvature radius at both ends and a small curvature radius in the middle, thereby forming a flow channel with one wide end and one narrow end between the two boundaries, and the flow channel gradually shrinks from the inlet to the outlet.

[0007] In the aforementioned flow equalization structure in the printed circuit board heat exchanger head, the transverse width w of the narrowest end of the crescent-shaped flow channel a and the crescent-shaped flow channel b is 3-5 mm.

[0008] In the aforementioned flow equalization structure in the printed circuit board heat exchanger head, the included angle between the extension line of the crescent-shaped flow channel outlet and the symmetry axis is 40-70°. α

[0009] In the aforementioned flow equalization structure in the printed circuit board heat exchanger head, the short axis of the semi-elliptical cavity is 20-40 mm, and the ratio of the long axis to the short axis is 1.2-1.5.

[0010] In the aforementioned flow equalization structure in the printed circuit board heat exchanger head, the included angle between the two straight boundaries of the gradually expanding cavity outlet is 90-130°. β

[0011] In the aforementioned flow equalization structure in the printed circuit board heat exchanger head, the triangular flow distribution array is composed of more than one triangular array of the same specification, the top angle of each triangle faces the gradually expanding cavity outlet direction, and the top angle is 30-45°.

[0012] In the aforementioned flow equalization structure in the printed circuit board heat exchanger head, the triangular flow distribution array includes two rows, and the triangles in the two rows are staggered in the arrangement along the fluid flow direction.

[0013] In the aforementioned flow equalization structure in the printed circuit board heat exchanger head, in the triangular flow distribution array, the gap between the adjacent two triangles in the row away from the semi-elliptical cavity is communicated with the heat exchange channel of the heat exchange core body.

[0014] ​​The beneficial effects of the present application are as follows: the present application sets a specific geometry at the inlet head of the heat exchanger, so that the fluid before entering the core forms a periodic flow distribution in the space in the transverse direction. The axisymmetric arrangement of the crescent-shaped flow channel promotes the formation of two flow beams with different directions, which are dynamically reorganized after merging into the semi-elliptical cavity. The configuration inside the cavity and the subsequent diverging channel jointly induce a non-steady transverse oscillatory flow pattern. The opening angle of the diverging structure controls the spread of the flow beam in the cavity before entering the core, so that the fluid realizes transverse sweeping in the plane. The two rows of staggered triangular shunt units inside the cavity before the core spatially segment the sweeping flow in structure, guiding it to enter the core inlet area in a dispersed and nonlinear manner. The above structure realizes the adjustment of the spatial distribution of the flow entering the core by inducing periodic disturbance and asymmetric distribution through geometry without movable parts. Therefore, the flow channels in the core alternately obtain different flow levels at different time periods, avoiding long-term flow deviation between flow channels and improving the balance of the heat exchanger under variable conditions and the utilization rate of the effective heat exchange area.

[0015] In summary, the present application can realize transverse periodic sweeping discharge at the head without moving devices. This structure allows the flow of all flow channels in the core to periodically change between large and small flow rates, avoiding the problem of some flow channels in the core always having large or small flow rates, thereby improving the heat exchange effect of the heat exchanger. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a structural schematic diagram of the present application; Figure 2 is a structural schematic diagram of the crescent-shaped flow channels a and b; Figure 3 is a structural schematic diagram of a single crescent-shaped flow channel; Figure 4 is a schematic diagram of the operating principle of the fluid oscillator of the present application, showing the fluid flow on both sides and the distribution of vortices during the oscillation process; Figure 5 is a schematic diagram of the overall fluid flow inside the head of the present application, the fluid forms a periodic flow distribution in the transverse direction in space after passing through the oscillator, and is guided into the flow channel through the triangular shunt array. DETAILED DESCRIPTION

[0017] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will combine the drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0018] The features and illustrative embodiments of various aspects of the present application will be described below in detail. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one of ordinary skill in the art that the present application can be practiced without some of these specific details. The following description of embodiments is merely exemplary in nature and is provided to give a better understanding of the present application. The present application is not limited to any particular setting or method set forth in the following description, but covers any improvements, alternatives, and modifications of the structures, methods, devices, etc. without departing from the spirit of the present application. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessary obscurity of the present application.

[0019] It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict, and each embodiment can be referred to and cited by each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0020] Embodiment 1. A micro-channel heat exchanger head with a fluid oscillator, referring to Figures 1-5 , the structure includes a fluid inlet 1, a crescent-shaped flow channel a2, a crescent-shaped flow channel b3, a semi-elliptical cavity 4, a gradually expanding cavity outlet 5, a core front cavity 6, and a triangular shunt array 7 arranged in the core front cavity.

[0021] The fluid inlet 1 is a circular structure for receiving heat exchange medium from the outside. Its two sides are connected with the crescent-shaped flow channel a2 and the crescent-shaped flow channel b3, respectively. The two flow channels are arranged in axial symmetry, the outer edge of the flow channel is a continuous circular arc 8, and the inner edge is an inner arc line 9 with a large curvature radius at both ends and a small curvature radius in the middle, forming a contraction type channel with one wide end and one narrow end, which promotes the formation of a direction-controlled double-beam flow during fluid flow. The outlet width w of each flow channel is controlled between 3 to 5 millimeters, which helps to form disturbance in subsequent flow.

[0022] The outlet of the crescent-shaped flow channel is introduced into the lower semi-elliptical cavity 4 at an angle (40° to 70°), which plays a role in reorganizing the fluid flow direction, with the short axis controlled at 20-40 mm and the long-to-short axis ratio ranging from 1.2 to 1.5 to ensure the convergence effect. The lower part of the semi-elliptical cavity 4 is connected to the gradually expanding cavity outlet 5, which is composed of two straight lines with an opening angle ranging from 90° to 130°, used to expand the reorganized flow and guide it to form a transverse oscillation mode.

[0023] The two fluid streams from the crescent-shaped flow channel a2 and the crescent-shaped flow channel b3 are introduced into the lower semi-elliptical cavity 4 at an angle after leaving their narrowest ends. In the semi-elliptical cavity 4, due to the opposite flow directions of the two fluid streams, their flow momentum directly collides and interferes in space, forming two opposing flow zones inside the cavity. This flow structure causes the dominant path of the fluid in the semi-elliptical cavity 4 to constantly shift between left and right. Due to the alternating forces exerted by the fluids on both sides in space, the overall direction of the fluid near the outlet exhibits a stable periodic oscillation trend.

[0024] This oscillation phenomenon is formed by the mutual competition of the fluids transported by the crescent-shaped flow channel a2 and the crescent-shaped flow channel b3 in the cavity 4. At each moment, the fluid on one side dominates in space, pushing the main flow to extend towards the outlet direction of that side to the gradually expanding cavity outlet 5; but as the momentum of the fluid on the opposite side accumulates, the direction of the fluid's action reverses, and the main flow path shifts to the opposite side, causing the flow direction to alternate. This process can continue to operate without external control or feedback structure, exhibiting a stable periodic characteristic.

[0025] Especially in the transition area between the semi-elliptical cavity 4 and the gradually expanding cavity outlet 5, the space where the fluid is located gradually expands, providing favorable conditions for the shift and expansion of the main flow direction. This spatial change amplifies the mutual interference between the fluids, enhancing the asymmetry of the overall flow and helping to form a complete periodic oscillation cycle. Through this structural design, the fluid from the fluid inlet 1, after entering, is guided by the crescent-shaped flow channel a2 and the crescent-shaped flow channel b3, reorganized in the semi-elliptical cavity 4, and expanded at the gradually expanding cavity outlet 5, achieving periodic disturbance without any movable parts, providing a stable inlet basis for the subsequent uniform flow and heat exchange process.

[0026] The core front cavity 6 is located behind the gradually expanding outlet 5, and the inside of the core front cavity 6 is provided with a flow distribution array 7 composed of a plurality of triangular units. The flow distribution array is arranged in a staggered structure of two rows, the top angle of the unit is directed to the gradually expanding port, and the top angle is 30 DEG to 45 DEG. The first row of units is arranged vertically to the heat exchange channel 10 direction of the heat exchange core, and the second row is arranged in a staggered manner below the first row, and the center of the second row is aligned with the gap between two adjacent heat exchange channels 10 in the core. The fluid entering the gap can be effectively induced to periodically distribute in the transverse direction.

[0027] The structure realizes nonlinear disturbance of the fluid under the premise of no movable parts, promotes the fluid to oscillate transversely and be distributed asymmetrically before entering the heat exchange channels of the core, and then realizes alternating flow supply between the channels in time, thereby relieving the long-term flow deviation problem. Therefore, the balance, heat exchange efficiency and effective heat exchange area utilization rate of the heat exchanger under variable load conditions can be improved.

[0028] The application provides a flow equalization structure in a micro-channel heat exchanger head with a fluid oscillator.

[0029] The processing method can include the following steps: The embodiment provides a manufacturing method for a flow equalization structure in a micro-channel heat exchanger head region. The method is suitable for a laminated heat exchanger with a metal multilayer structure, and a chemical etching process is used to accurately build a preset geometric structure on a single metal plate. The method is suitable for stainless steel, nickel-based alloy, titanium alloy and other metal materials widely used in high-temperature and high-pressure heat exchange scenes, has high manufacturing precision and can realize batch production.

[0030] Firstly, a metal sheet with a thickness of 0.8 mm to 1.5 mm is selected as an etching substrate. After the metal plate is cut, degreased and surface activated, the residual oxide layer and organic impurities on the surface are removed, so that the uniform adhesion of the subsequent photoresist layer and the pattern transfer precision are ensured.

[0031] Then, a positive photoresist or dry film photoetching material is applied to the surface of the substrate. The thickness of the photoresist layer is controlled to be in the range of 10 to 20 microns by using a hot roller film coating or spin coating technology, so as to ensure the subsequent pattern precision and etching boundary definition.

[0032] Subsequently, a high-resolution mask pattern including a crescent-shaped flow channel, a semi-elliptical cavity, a gradually expanding channel and a triangular flow distribution array pattern is accurately transferred to the photoresist layer by an alignment exposure device. The exposure wavelength is selected according to the type of the photoresist (such as a 365 nm i-line light source), and the exposure dose is controlled in a suitable range to avoid pattern edge diffusion.

[0033] After the non-exposed area is removed by the developing process, the surface of the metal plate only retains the photoresist layer of the pattern covered area. At this time, the plate is immersed in an etching solution containing ferric salt for chemical corrosion. The etching solution can be FeCl3 solution with a mass fraction of 35%-5%, the etching temperature is controlled at 40-50℃, and the time is determined according to the etching depth and the complexity of the channel pattern, usually not more than 10 minutes.

[0034] After etching, the plate is taken out, the residual photoresist layer is removed with a stripping solution (such as an alkaline stripping solution), and the surface residues are washed with deionized water. After drying, a single-layer metal plate with complete and uniform flow structure is obtained. The etching depth is controlled between 0.2-0.6 mm, and the edge profile is sharp without burrs.

[0035] If a complete multi-layer structure is required, the etched single plate can be stacked and positioned with other cold and hot runner plates, and vacuum diffusion welding, hot isostatic pressing (HIP) or brazing can be used to realize the overall combination of the structure. The welding process requires to be completed in a controlled temperature and pressure environment to ensure that the channel morphology does not collapse or warp at high temperature.

[0036] The manufacturing method avoids the problems of edge burrs and heat affected zone caused by mechanical milling or laser cutting, and has the advantages of low manufacturing cost, high pattern consistency and strong adaptability, and is particularly suitable for the manufacturing of high-efficiency micro-channel heat exchangers with complex structure and high precision requirements for channel morphology.

[0037] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements should be covered within the protection scope of the present application.

Claims

1. A flow equalizing structure in a printed circuit board type heat exchanger header, characterized by, The fluid inlet (1) is symmetrically distributed with crescent-shaped flow channels a (2) and b (3) on both sides, the crescent-shaped flow channels a and b are symmetrically connected with the arc-shaped top of the semi-elliptical cavity (4), the middle of the bottom of the semi-elliptical cavity (4) is connected with the front cavity (6) of the core through the gradually expanding cavity outlet (5), and the triangular shunt array (7) is arranged in the front cavity (6) of the core.

2. The flow equalization structure in the printed circuit board heat exchanger header according to claim 1, characterized in that, The outer boundary of each crescent-shaped flow channel is a continuous circular arc (8), and the inner boundary is an inner arc line (9) with a large curvature radius at both ends and a small curvature radius in the middle, thereby forming a flow channel with one wide end and one narrow end between the two boundaries, and the flow channel gradually shrinks from the inlet to the outlet.

3. The flow equalizing structure within the header of a printed circuit board heat exchanger according to claim 1, wherein The transverse width w of the narrowest end of the crescent-shaped flow channel a (2) and the crescent-shaped flow channel b (3) is 3-5 mm.

4. The flow equalizing structure within the header of a printed circuit board heat exchanger of claim 1, wherein, The included angle between the extension line of the crescent-shaped runner outlet and the symmetry axis α is 40-70°.

5. The flow equalizing structure within the header of a printed circuit board heat exchanger of claim 1, wherein, The short axis of the semi-elliptical cavity (4) ranges from 20 to 40 mm, and the ratio of the long axis to the short axis ranges from 1.2 to 1.

5.

6. The flow equalizing structure within the header of a printed circuit board heat exchanger of claim 1, wherein, The included angle between the two straight boundaries of the gradually expanding cavity outlet (5) β The range is 90° to 130°.

7. The flow equalizing structure within the header of a printed circuit board heat exchanger of claim 1, wherein, The triangular shunt array (7) is composed of more than one triangular array of the same specification, the top angle of each triangle faces the direction of the gradually expanding cavity outlet (5), and the top angle ranges from 30 to 45 degrees.

8. The flow equalizing structure within the header of a printed circuit board heat exchanger according to claim 7, characterized in that, The triangular shunt array (7) includes two rows, and the triangles in the two rows are staggered in the arrangement along the fluid flow direction.

9. The flow equalizing structure within the header of a printed circuit board heat exchanger according to claim 8, characterized in that, In the triangular shunt array (7), the gap between the two adjacent triangles in the row away from the semi-elliptical cavity (4) is in communication with the heat exchange channel (10) of the heat exchange core.

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