Resistance reducing fin of printed circuit board heat exchanger

Abstract

The utility model provides a printed circuit board heat exchanger resistance-reducing fin which comprises a plurality of fins which are discontinuously arranged on a heat exchange plate, the windward side of the head of each fin is a concave curved surface, the middle of each fin is a smooth straight surface, and a streamline curved surface of the tail of a traditional wing-shaped fin is reserved at the tail of each fin. The fin can greatly reduce resistance loss caused by fin head stagnation points and fin middle-rear part negative pressure gradient and flow separation, obviously reduce flow resistance and pressure loss of the heat exchanger, and improve comprehensive heat exchange capability of the printed circuit board heat exchanger.

Description

Technical Field

[0001] This utility model belongs to the technical field of microchannel heat exchanger fins, specifically a drag-reducing fin for a printed circuit board heat exchanger. Background Technology

[0002] Driven by the pursuit of higher energy conversion efficiency, a high-efficiency, compact printed circuit board heat exchanger (PCHE) based on chemical etching and diffusion welding technology has broken through the performance bottleneck of traditional heat exchangers. Its core structure consists of multiple stacked heat exchange plates. Millimeter-scale microchannels are etched into the heat exchange plates, and then the cold and hot side heat exchange plates are alternately welded into a whole using vacuum diffusion welding technology. The PCHE has a specific surface area of ​​up to 2500 m². 2 / m 3 Its extremely high compactness and excellent resistance to high and low temperatures (-200℃~900℃) and high pressure (>30MPa) make it of great application value in advanced energy systems such as solar power generation, ultra-high temperature gas-cooled reactors, and nuclear fusion reactor cooling.

[0003] Existing research classifies the channel structure of printed circuit board heat exchangers (PCHEs) into two categories:

[0004] (1) Continuous structural channels (such as straight channels and wavy channels) have continuous flow paths and low pressure loss, but thicker boundary layers will limit heat transfer performance.

[0005] (2) Discontinuous structural channels (such as airfoil ribs, rhomboid ribs, and S-shaped ribs) disrupt the flow boundary layer through periodically arranged discontinuous ribs, enhancing fluid mixing and improving heat transfer efficiency, but also increasing flow resistance. Current research considers airfoil ribs and rhomboid ribs to have better overall performance, but due to the large negative pressure gradients generated at the leading edge stagnation point and the sharp inflection point in the middle of the ribs, which separate the flow, further optimization of their rib structure is needed to overcome the large flow resistance and pressure loss, and improve the overall heat transfer performance of the PCHE channel in the printed circuit board heat exchanger.

[0006] It should be noted that the above technical information is intended only to enhance the understanding of the overall background technology of this utility model, and should not be regarded as an admission or in any form an implication that the above technical information constitutes prior art known to those skilled in the art. Utility Model Content

[0007] To address the shortcomings in the aforementioned background technology, this utility model optimizes the existing airfoil and rhomboid fin structures and proposes a drag-reducing fin for printed circuit board heat exchangers. This significantly reduces the flow resistance and pressure loss caused by the stagnation point at the fin head and the negative pressure gradient and flow separation in the middle and rear of the fin, thereby improving the overall heat exchange capacity of the printed circuit board heat exchanger.

[0008] The technical solution of this application is as follows:

[0009] A heat exchanger for printed circuit boards with drag reduction fins includes several fins that are discontinuously arranged on a heat exchange plate. The front face of the fins is a concave curved surface, the middle is a smooth straight surface, and the tail retains the streamlined curved surface of a traditional airfoil fin.

[0010] Furthermore, the rib is made of two NACA00 series airfoil ribs of the same size and chord length, which are cross-joined along the axis of symmetry of the length direction of the airfoil rib, retaining the tail portion. Two symmetrical vertices B are formed at the cross-joining point. The convex curved surface of the head of the rib is flipped into a concave curved surface along the axis of symmetry of the line connecting the two symmetrical vertices B and the head vertex A of the rib. Then, the sharp inflection point B at the cross-joining point is replaced with a smooth straight surface, and the tail portion retains the streamlined curved surface of the original NACA00 series airfoil rib.

[0011] Furthermore, the length L of the rib c The width L of the rib is 4.0-16.0 mm. w The rib has a diameter of 0.8-3.2 mm and a height L. h It is 1.5-2mm.

[0012] Furthermore, the fins are arranged in an alternating pattern on the heat exchange plate, with a vertical spacing L between adjacent fins. t The horizontal spacing L between adjacent ribs is 1.6-6.4 mm. z The spacing between adjacent ribs is 4.0-16mm. k It is 4.0-16mm.

[0013] The specific beneficial effects of this utility model include:

[0014] 1. In this utility model, the windward surface of the rib head adopts a concave curved surface instead of the traditional convex curved surface of the rib. Numerical studies have shown that, within a mass flow rate range of 1.057–4.017 g / s, the pressure loss at the head of the rib is reduced by 10.89% compared to existing airfoil ribs and rhomboid convex curved surface ribs.

[0015] 13.21% and 3.28%–5.26%;

[0016] 2. In this invention, the middle section of the rib uses a smooth, straight surface instead of a sharp inflection point. Numerical studies within the mass flow rate range of 1.057–4.017 g / s show that, compared to existing airfoil-shaped and rhomboid ribs with a sharp inflection point in the middle, the negative pressure gradient of the rib is reduced by 57.14%–76.53%.

[0017] and 14.29% to 25.00%;

[0018] 3. Considering the above-mentioned optimization effects of the fin structure, the overall heat exchange performance (the ratio of heat transfer factor to friction factor j / f) of the printed circuit board heat exchanger of this utility model is improved by 5.19% to 9.20% and 1.90% to 2.65% compared with the existing airfoil fins and rhomboid fins, respectively. It effectively reduces the flow resistance and pressure loss of the heat exchange fluid and improves the overall heat exchange capacity of the heat exchanger. Attached Figure Description

[0019] To more clearly illustrate the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the fins on the heat exchange plate in this utility model;

[0021] Figure 2 This is a cross-sectional view of the NACA00 series airfoil ribs;

[0022] Figure 3 The cross-sectional view and side view of the rib in this utility model are shown.

[0023] Figure 4 This is a diagram showing the arrangement of adjacent fins on the heat exchange plate in this utility model;

[0024] Figure 5 This is a three-dimensional schematic diagram of the core structure of a supercritical fluid printed circuit board heat exchanger using the ribs of this utility model.

[0025] Explanation of icon numbers:

[0026] 1. Ribs;

[0027] 2. Heat exchange plate;

[0028] 10. Heat exchanger plate one;

[0029] 20. Heat exchanger plate two;

[0030] 30. Single-channel heat exchange fluid;

[0031] 40. Two-channel heat exchange fluid. Detailed Implementation

[0032] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the core concept of the present utility model and the following embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0033] These embodiments are provided to make the application thorough and complete, and to fully express the scope of the application to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​illustrated in these embodiments should be interpreted as merely exemplary and not as limiting.

[0034] A type of printed circuit board heat exchanger drag-reducing fin, such as Figures 1-3 As shown, it includes several fins 1 that are not continuously arranged on the heat exchange plate 2. The head of the fin 1 has a concave curved surface, the middle part has a smooth straight surface, and the tail part retains the streamlined curved surface of the traditional airfoil fin.

[0035] Specifically, the rib 1 is composed of two NACA00 series airfoil ribs of the same size and chord length, which are intersected along the axis of symmetry in the length direction of the airfoil ribs, retaining the tail portion. The intersection forms two symmetrical vertices B, as shown in [reference needed]. Figure 2 Along the axis of symmetry connecting the two symmetrical vertices B and the vertex A of the rib head, the convex surface of the head of rib 1 is flipped into a concave surface. Then, the sharp inflection point B at the intersection is replaced with a smooth straight surface. The tail retains the streamlined surface of the original NACA00 series airfoil rib. See Figure 3 .

[0036] Specifically, the NACA00 series airfoil ribs are existing technology, a series of airfoils developed by the National Advisory Committee on Aeronautics (NACA). Each airfoil's designation consists of the four letters "NACA" followed by a string of numbers, where the numbers represent the airfoil's geometric parameters.

[0037] As one implementation method, such as Figure 5 As shown, in the printed circuit board heat exchanger core composed of alternating stacked heat exchange fluid channels 30 and 40, supercritical CO2 is introduced into heat exchange fluid channel 30 as the heat fluid. Several discontinuously arranged fins 1 are etched onto its heat exchange plate 10 using chemical etching. The length L of the fins 1 is... c 4.0mm, width L w0.8mm, height L h The fins 1 are arranged alternately on the heat exchange plate 10 with a diameter of 1.5 mm. The vertical distance L between adjacent fins 1 is 1.5 mm. t The horizontal spacing L between adjacent ribs 1 is 1.6 mm. z The spacing L between adjacent ribs 1 is 4.0 mm. k The diameter is 4.0 mm; the second heat exchange fluid channel 40 serves as a cold fluid channel to cool the supercritical CO2 fluid in the first heat exchange fluid channel 30. The second heat exchange plate 20 can be selected according to the type of fluid and the heat exchange process, and the appropriate channel structure can be selected.

[0038] The pressure loss ΔP, friction factor f, heat transfer factor j, and the ratio j / f (reflecting the overall heat transfer performance of the channel) on the supercritical working fluid side of the printed circuit board heat exchanger using the fins of this invention were numerically calculated using FLUENT flow heat transfer numerical simulation software. The calculation results were compared with those of the NACA0025 airfoil fin printed circuit board heat exchanger with the same chord length and arrangement on the supercritical working fluid side. Table 1 lists the numerical model and its parameter settings.

[0039] Table 1 Numerical Model and Parameter Settings

[0040]

[0041] Table 2 lists the numerical calculation results of the pressure loss ΔP, friction factor f, and the ratio of heat transfer factor to friction factor j / f (reflecting the overall heat transfer performance) on the supercritical working fluid side of the printed circuit board heat exchanger with the new finned structure, when the outlet pressure is 20 MPa, the inlet temperature is 686 K, and the inlet mass flow rate increases in the range of 1.057 to 4.017 g / s under a fixed cooling load. The results are compared with the corresponding calculation results on the supercritical working fluid side of the NACA0025 airfoil fin printed circuit board heat exchanger.

[0042] Table 2

[0043]

[0044] As can be seen from Table 2, compared with the NACA0025 airfoil fins, the pressure loss ΔP on the supercritical working fluid side of the printed circuit board heat exchanger of the present invention is reduced by 19.47% to 22.37%, the friction factor f is reduced by 11.02% to 16.55%, and the ratio j / f of the heat transfer factor to the friction factor in the overall heat exchange performance is increased by 5.19% to 9.20%.

[0045] The data above show that the flow resistance and pressure loss of the printed circuit board heat exchanger with the finned structure of this invention are significantly reduced, and the overall heat exchange capacity of the heat exchanger is significantly improved.

[0046] Any aspects of this utility model that are not detailed herein are conventional technical means known to those skilled in the art.

[0047] The above content shows and describes the basic principles, main features, and beneficial effects of this utility model. The above description is merely a preferred embodiment of this utility model and is not intended to limit it. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A heat exchanger drag-reducing fin for a printed circuit board, characterized in that: It includes several non-continuously arranged fins (1) on the heat exchange plate (2). The front of the fin (1) is a concave curved surface, the middle is a smooth straight surface, and the tail retains the streamlined curved surface of the traditional airfoil fin.

2. The printed circuit board heat exchanger drag-reducing fins according to claim 1, characterized in that: The rib (1) is made of two NACA00 series airfoil ribs of the same size and chord length. They are cross-joined along the axis of symmetry of the length direction of the airfoil rib, and the tail part is retained. Two symmetrical vertices B are formed at the cross-joining point. The convex curved surface of the head of the rib (1) is flipped into a concave curved surface along the axis of symmetry of the line connecting the two symmetrical vertices B and the head vertex A of the rib. Then the sharp inflection point B at the cross-joining point is replaced by a smooth straight surface. The tail part retains the streamlined curved surface of the original NACA00 series airfoil rib.

3. The printed circuit board heat exchanger drag-reducing fins according to claim 1, characterized in that: The length L of the rib (1) c 4.0-16.0mm, width L w 0.8-3.2mm, height L h It is 1.5-2mm.

4. The printed circuit board heat exchanger drag-reducing fins according to claim 1, characterized in that: The ribs (1) are arranged alternately on the heat exchange plate (2), and the vertical distance L between adjacent ribs (1) is... t The horizontal spacing L between adjacent ribs is 1.6-6.4 mm. z The spacing between adjacent ribs is 4.0-16mm. k It is 4.0-16mm.

5. The printed circuit board heat exchanger drag-reducing fins according to claim 1, characterized in that: The heat exchanger using finned (1) printed circuit board has a core composed of multiple layers of hot and cold fluid heat exchange plates stacked alternately. The finned (1) fluid heat exchange plates have several rows and columns of fins (1), with adjacent rows and / or adjacent columns of fins (1) arranged alternately.

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