Planar heat exchanger with interchangeable flow directions

Abstract

The invention discloses a planar heat exchanger with interchangeable flow directions, and relates to the technical field of heat dissipation of electronic equipment. The heat exchanger is formed by sequentially connecting a first flow dividing area, a heat exchange area and a second flow dividing area. The first flow dividing area and the second flow dividing area are arranged in a mirror symmetry mode relative to the heat exchange area and have completely same geometric outlines. The heat exchange area is rectangular; the first flow dividing area and the second flow dividing area are planar variable cross-section runners, the widest cross-section end is connected with the heat exchange area, the narrowest cross-section end is connected with a fluid inlet or outlet, and the fluid inlet or outlet is centrally arranged relative to a flow direction shaft; a central rectifying body is arranged at the center of a flow direction shaft in the first flow dividing area and the second flow dividing area; the purpose that the flow directions of the heat exchangers can be exchanged is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of heat dissipation of electronic equipment, and in particular to a liquid cooling device suitable for heat dissipation of high-power electronic devices. Background Art

[0002] A cooling plate is a derivative of a heat exchanger. A heat exchanger is used to achieve heat exchange between fluids. The most widely used interlayer heat exchanger (different fluid media are not in direct contact) transfers heat from a high-temperature fluid to a low-temperature fluid via the heat exchanger wall plate to achieve heat exchange between the two fluids. The heat exchanger wall plate (tube or plate) is mostly made of metal materials with high thermal conductivity, good strength and toughness, and easy to obtain and process. A cooling plate can be understood as half a heat exchanger, which is used to achieve heat exchange between fluids and solids. The heat of the cooling plate is transferred from the heat source on the solid side to the low-temperature fluid via the cooling plate wall plate, or from the high-temperature fluid to the heat sink on the solid side via the cooling plate wall plate to achieve heat exchange between solids and liquids. Due to the different characteristics of the heat exchange objects, the heat exchanger can arrange cold and hot fluids at intervals, and achieve a higher area-to-volume ratio through spatial stacking, while the cooling plate can only arrange a layer of fluid, making it difficult to achieve a higher area-to-volume ratio.

[0003] Cold plates are commonly used for heat dissipation of electrical, electronic, and power equipment. Depending on the fluid medium used, they can be divided into two categories: air-cooled plates and liquid-cooled plates. Since the density, specific heat capacity, and thermal conductivity of liquids are much greater than those of gases, under the same available temperature difference conditions, the heat exchange efficiency and heat capacity of liquid-cooled plates are much greater than those of air-cooled plates, and the volume is also more compact. In the absence of other factors with higher weight, liquid-cooled plates are preferred for heat dissipation of high-power equipment.

[0004] At present, multi-return integral liquid cooling plates are the mainstream form of heat dissipation for high-power electrical, electronic, and power equipment. Its design principle is to design uniform temperature for large-area uniform heat sources and maximize the use of the hot side area. It can realize the cooling of electronic modules (or electrical modules, hereinafter referred to as electronic modules for simplified description) with medium heat dissipation power and medium heat flux density, and is insensitive to the type, quantity and arrangement order of electronic modules. It has good adaptability and can be called a universal liquid cooling plate. However, it has been found in engineering practice that liquid cooling plates with uniform temperature design cannot enhance the local heat exchange capacity for local high heat flux density point heat sources, resulting in overheating in some areas and underheating in other areas, wasting the heat capacity of the coolant. Its design characteristics and performance are difficult to meet the cooling requirements of a certain type of electronic modules with distributed point heat source characteristics. Therefore, it is necessary to develop a special liquid cooling plate that is different from the design concept of the universal liquid cooling plate.

[0005] The core of a certain type of electronic module is multiple groups of regularly arranged power devices. The heat dissipation power of power devices usually accounts for more than 90% of the heat dissipation power of such electronic modules. Since the circuit composition within a single group is exactly the same and the groups are connected in parallel, the power devices are arranged neatly and concentrated in a local area of ​​the planar circuit, which has the typical characteristics of non-uniform and distributed point heat sources. A single power device usually has the properties of high heat flux density and high power at the same time, with prominent point heat source characteristics and very poor (planar) thermal expansion effect of the heat conductor. Special liquid cold plates can enhance local heat exchange capabilities based on the layout characteristics of its power devices, and better solve the cooling problem of non-uniform and distributed point heat sources.

[0006] The special liquid cooling plate is designed with the concept of "hot end small system". Its concept can refer to the cooler flow path described in the patent "A cooler flow path with symmetrical topological structure and double heat dissipation surface liquid cooling plate" (ZL201910328141.9). A "hot end small system" suitable for passive mode of single-phase liquid is usually an open flow path composed of components such as heat exchangers, splitters, mixers and connecting flow channels. The "heat exchanger" mentioned here refers to a structural whole composed of a number of regularly arranged heat dissipation teeth, wall panels, and flow channels (including upstream and downstream expansion sections). Two surfaces serve as fluid inlet and outlet, respectively, and the remaining surfaces are closed surfaces; it can appear in the form of an independent structural part (such as a cooling device for a commercial computer CPU or GPU) with obvious structural separable surfaces, or it can appear in an integrated form without structural separable surfaces. Due to the planar properties of the flow path of the special liquid cooling plate, the planar heat exchanger is its key flow path component. From the perspective of enhancing the convective heat transfer effect, reducing the hydraulic equivalent diameter of the channel and increasing the heat exchange surface area are both effective technical measures. In order to control the flow resistance, the mainstream of planar heat exchangers is to use parallel channels, that is, parallel flow heat exchangers. Parallel channels inevitably involve the problem of uniform distribution of flow, so planar heat exchangers are usually composed of upstream structures, heat exchange areas and downstream structures in series, and the heat exchange area is the area where the parallel channels are located. According to the relative relationship between the inlet and outlet flow directions and the flow directions in the channels, planar heat exchangers can be divided into two types: baffle heat exchangers and direct flow heat exchangers.

[0007] The upstream and downstream structures of the baffle heat exchanger are both static pressure chambers (i.e., large spaces). Based on the principle of static pressure diversion, the velocity component perpendicular to the channel flow direction is first stagnated to zero at the upstream of the channel, and the velocity component parallel to the channel flow direction is increased synchronously to complete the first 90° turn of the flow. Then, the velocity component parallel to the channel flow direction is stagnated to zero at the downstream of the channel, and the velocity component perpendicular to the channel flow direction is increased synchronously to complete the second 90° turn of the flow. According to the similarities and differences in the inlet and outlet flow directions, the baffle heat exchanger can be further divided into two types: heat exchangers with different inlet and outlet sides (Z type) and heat exchangers with same inlet and outlet sides (U type). The upstream and downstream structures of the baffle heat exchanger were originally rectangular static pressure chambers, which were changed into trapezoidal static pressure chambers with equal area flow after analysis and optimization. The characteristics of the baffle heat exchanger can also be referred to the series combination of two heat exchangers with different technical specifications described in the patent "A cooler flow path and double heat dissipation surface liquid cooling plate with symmetrical topological structure" (ZL201910328141.9).

[0008] However, baffle heat exchangers have two 90° flow turns and a process where the flow velocity stagnates to zero, resulting in a large flow resistance. In addition, in terms of circuit layout, the length of a single circuit in the direction of the circuit is relatively free, while the width of a single circuit and the distance between multiple circuits in parallel are relatively small. The flow direction of the channel of a baffle heat exchanger is usually parallel to the width direction of a single circuit, resulting in a shorter channel and a larger number of parallel connections, which is not conducive to convective heat transfer. The series combination of two heat exchangers of different technical specifications described in the patent "A cooler flow path and double heat dissipation surface liquid cooling plate with a symmetrical topological structure" (ZL201910328141.9) has improved this, making the flow direction in the heat exchanger channel parallel to the length direction of the circuit. In order to overcome these two shortcomings of the baffle heat exchanger, the concept of "direct current heat exchanger" is proposed, and the inlet and outlet are usually centered, rather than offset.

[0009] The flow direction in the direct-flow heat exchanger is constant, and the flow direction is consistent with the direction of the circuit. The larger length in the direction of the circuit can be fully utilized to increase the length of the channel, and the limitation in the width direction of the circuit can be used to reduce the difficulty of diversion. The upstream structure of the direct-flow heat exchanger is a planar diffuser, which decelerates and diffuses the pressure through the increasing cross section, and realizes the uniform distribution of the flow. Its downstream structure is a planar nozzle, which decompresses and increases the speed through the decreasing cross section, and sucks the fluid in the channel. The diffuser and nozzle of the direct-flow heat exchanger can adopt the same geometric design, that is, the symmetrical direct-flow heat exchanger, which has a relatively simple design and the flow direction is reciprocal. However, diffuser flow and nozzle flow are two different flow phenomena after all. The same expansion angle (or contraction angle) cannot meet the requirements of the two flows at the same time. For example, a smaller expansion angle leads to a larger size of the flow separation vortex in the diffuser, while a larger contraction angle leads to an increase in the flow resistance in the nozzle. In order to solve this problem, the diffuser and nozzle of the direct-flow heat exchanger can also adopt different geometric designs, that is, an asymmetric direct-flow heat exchanger, but the flow direction is determined and the flow resistance will be slightly increased. The characteristics of these two types of direct-flow heat exchangers can be referred to the relevant description of direct-flow heat exchangers in the patent "A unit flow path, heat exchanger, and liquid cooling plate" (ZL202210019804.0).

[0010] Asymmetric direct-flow heat exchangers can well match the diffuser flow upstream of the parallel slots and the nozzle flow downstream. However, the flow direction of the asymmetric direct-flow heat exchanger is fixed. If the flow is reversed, the design effect will be greatly reduced, which is worse in some application scenarios where the flow needs to be reciprocal to simplify the design difficulty. Secondly, dedicated liquid cooling plates are generally designed as thin-walled pressure-resistant structures, and the cavity structure upstream / downstream of the parallel slots is the first pressure damage area. The larger the number of parallel slots, the larger the cavity structure of the diffuser (or nozzle) based on the same expansion angle (or contraction angle), the lower the pressure resistance, and the lower the structural safety. Based on these two shortcomings, it is necessary to develop a new symmetrical direct-flow heat exchanger to supplement the asymmetric direct-flow heat exchanger. Summary of the invention

[0011] The object of the present invention is to provide a planar heat exchanger with interchangeable flow directions, so as to achieve the purpose that the flow directions of the heat exchanger can be interchanged and the size of the heat exchanger can be adjusted according to the area of ​​the heat source (ie, it has scalability).

[0012] In order to achieve the above object, the present invention adopts the following technical means: A planar heat exchanger with interchangeable flow directions, which is formed by sequentially connecting a first flow splitting area, a heat exchange area and a second flow splitting area; the first flow splitting area and the second flow splitting area are arranged in mirror symmetry with respect to the heat exchange area and have completely the same geometric profile; The heat exchange area is rectangular and is formed by a number of grooves and teeth parallel to the flow axis and arranged regularly at intervals; The first flow splitting area and the second flow splitting area are both plane variable cross-section flow channels, the widest cross-section end is connected to the heat exchange area, and the narrowest cross-section end is connected to the fluid inlet or outlet, and the fluid inlet or outlet is centered relative to the flow axis; in the first flow splitting area and the second flow splitting area, there is a central rectifier at the center of the flow axis, and there is a distance between the central rectifier and the fluid inlet or outlet and the parallel channels of the heat exchange area; When the fluid flows through the first diversion area, the heat exchange area and the second diversion area in sequence, the first diversion area behaves as a diffuser and the second diversion area behaves as a nozzle; when the fluid flows through the second diversion area, the heat exchange area and the first diversion area in reverse order, the second diversion area behaves as a diffuser and the first diversion area behaves as a nozzle.

[0013] Preferably, the expansion angle a of the first diversion area is equal to the contraction angle b of the second diversion area, and the expansion angle a and the contraction angle b are between 45° and 90°.

[0014] Furthermore, the central rectifying body is an elongated cylinder, comprising a straight side segment parallel to the flow axis and semicircular surfaces arranged at both ends of the straight side segment.

[0015] Furthermore, the size of the planar heat exchanger with interchangeable flow directions increases or decreases according to the area of ​​the heat source to be cooled. After the planar heat exchanger with interchangeable flow directions is enlarged, in the first diversion area and the second diversion area, a plurality of long cylindrical auxiliary rectifiers are symmetrically and spaced apart on both sides of the central rectifier, and the auxiliary rectifiers are arranged in parallel with the central rectifier or in a circular arc-shaped concentric radial arrangement.

[0016] Furthermore, when the auxiliary rectifier is arranged in parallel with the central rectifier, the length of the auxiliary rectifier gradually decreases in the direction away from the central rectifier, and one end of the auxiliary rectifier facing the heat exchange zone is flush with the end of the central rectifier facing the heat exchange zone, and the spacing between the rectifiers is equal or increases from the center to both sides.

[0017] Furthermore, when the auxiliary rectifier and the central rectifier are arranged concentrically and radially in an arc shape, the length of the central rectifier in the radial direction is greater than the length of the auxiliary rectifier, and the sizes of the auxiliary rectifiers are the same, and the end of the auxiliary rectifier close to the heat exchange zone and the end of the central rectifier close to the heat exchange zone are on the same virtual arc line; adjacent rectifiers are arranged at equal intervals.

[0018] Furthermore, the central rectifier and the auxiliary rectifier are arranged concentrically and radially in an arc shape, and the minimum angle between adjacent rectifiers is 15°.

[0019] Furthermore, the grooves in the heat exchange zone are straight grooves of equal cross-section, and the teeth are straight teeth of equal cross-section. The characteristic size and number of the grooves are independent of the size of the heat source area and are only determined by the size of the heat flux density of the heat source.

[0020] Furthermore, the box body and the cover plate are composed of two parts, which are connected as a whole by welding, and the welding positioning of the two parts is achieved by a group of positioning columns and positioning holes.

[0021] Furthermore, the box body includes a complete flow channel contour formed by the first diversion area, the heat exchange area and the second diversion area, a central rectifier, an auxiliary rectifier and a group of positioning holes; the cover plate includes all the heat dissipation teeth of the heat exchange area and a group of positioning columns.

[0022] The present invention has the following beneficial effects: The symmetrical direct-flow heat exchanger proposed in the invention increases the flow resistance by about 15% to 25% (related to the number and arrangement of the rectifier mechanisms) without affecting uniform flow distribution, but achieves the requirement of reciprocal flow direction of the heat exchanger and solves the problem of using the same type of dedicated liquid cooling plate in application scenarios that require flow direction exchange.

[0023] The symmetrical direct-flow heat exchanger proposed by the present invention greatly improves the problem of insufficient pressure resistance of the cavity area due to the presence of the rectifier, and further enhances the safety of the thin-wall pressure-resistant structure.

[0024] The symmetrical direct-flow heat exchanger proposed by the present invention has a simple structure, completely inherits the original manufacturing process, and does not increase material loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram and dimension definition of a planar heat exchanger with interchangeable flow directions according to the present invention.

[0026] Figure 2 A schematic diagram of a planar heat exchanger in one embodiment to demonstrate the scalability of the present invention.

[0027] Figure 3 A schematic diagram of a planar heat exchanger in another embodiment to illustrate the scalability of the present invention.

[0028] Figure 4 It is a schematic diagram of the composition of the planar heat exchanger with interchangeable flow channels of the present invention.

[0029] Figure 5 It is a schematic structural diagram of the box body of the planar heat exchanger of the present invention.

[0030] Figure 6 It is a schematic structural diagram of the cover plate of the planar heat exchanger of the present invention.

[0031] Among them, 1-first flow distribution area, 2-heat exchange area, 3-second flow distribution area, 8-central rectifier, 9-auxiliary rectifier, 10-box body, 11-cover plate, 12-heat dissipation teeth, 13-positioning holes, 14-positioning columns. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0035] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0036] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use, or the positions or positional relationships commonly understood by those skilled in the art, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] Please combine Figures 1 to 6 As shown, a planar heat exchanger with interchangeable flow directions comprises a first flow dividing area 1, a heat exchange area 2 and a second flow dividing area 3 arranged in sequence; the first flow dividing area 1 and the second flow dividing area 3 are arranged in mirror symmetry, and a rectifying mechanism is respectively built in the first flow dividing area 1 and the second flow dividing area 3; In the first flow dividing area and the second flow dividing area, there is a central rectifying body 8 at the center of the flow axis, and there is a distance between the central rectifying body 8 and the inlet or outlet of the fluid and the parallel channels of the heat exchange area; The first flow-dividing area 1 and the second flow-dividing area 3 of the planar heat exchanger have exactly the same geometric design. When the flow direction is determined, the upstream structure behaves as a diffuser, and the downstream structure behaves as a nozzle. Here, the first flow-dividing area 1 and the second flow-dividing area 3 can be used as the upstream structure or the downstream structure respectively. When the first flow-dividing area 1 is used as the upstream structure, the second flow-dividing area 3 is used as the downstream structure. When the second flow-dividing area 3 is used as the upstream structure, the first flow-dividing area 1 is used as the downstream structure. The planar heat exchanger corresponds to the power device in geometric position and has geometric dimensions comparable to those of the power device in the flow direction. A single heat exchanger can be used for heat collection of 1 to 2 power devices (single-point or double-point heat sources).

[0039] The downstream direction of the heat exchange zone 2 is the long side of the heat exchange zone, and the short side of the heat exchange zone is along the flow direction. The heat exchange zone is composed of a number of grooves and straight teeth arranged regularly, guiding the heat of the power device to be mainly conducted to the heat dissipation teeth in the vertical direction and exchange heat with the coolant, while the plane expansion area inside the wall plate is almost negligible. The characteristic size selection of the heat exchanger must follow the laws of physics.

[0040] First, the selection of the cross-sectional geometric parameters of the heat exchange zone 2 includes: the tooth height (or groove height) l, the groove width w and the tooth width t. According to the definition of Biot number (Bi) in heat transfer: ; Among them, k sis the solid thermal conductivity, h is the convective heat transfer coefficient, and L is the characteristic length; the Bi number characterizes the relative strength relationship between convective heat transfer and solid heat conduction. Usually, the heat transfer capacity is arranged from high to low as follows: liquid convection heat transfer, metal solid heat conduction, gas convection heat transfer.

[0041] For air-cooled plates, the heat conduction depth of metal solids is large, and the channel section of the heat exchanger is suitable for a larger aspect ratio (l / w), which is often greater than 20, resulting in a larger thickness of the air-cooled plate. The heat dissipation teeth of the air-cooled plate are relatively thin, and the ratio of the heat dissipation teeth thickness to the channel width is often less than 0.2.

[0042] For liquid cooling plates, the heat conduction depth of metal solids is small, and the heat exchanger channel section is suitable for a smaller aspect ratio (l / w), which is often less than 15 and is highly related to the ratio of the heat dissipation tooth thickness to the channel width (t / w), resulting in a smaller thickness of the liquid cooling plate. The heat dissipation teeth of the liquid cooling plate are thicker and have the function of increasing the compressive strength.

[0043] Next, regarding the channel length L f choice.

[0044] When the fluid flows into the pipe, a flow boundary layer will form at the wall. The thickness of the flow boundary layer increases along the flow direction. When the flow boundary layers on the opposite sides contact each other, the flow enters the fully developed section. The friction coefficient decreases monotonically from the initial point of the flow boundary layer, and then remains a constant value in the fully developed section. When there is a temperature difference between the fluid and the pipe wall, a thermal boundary layer will form at the wall. The thickness of the thermal boundary layer also increases along the flow direction. When the thermal boundary layers on the opposite sides contact each other, the thermal fully developed section is entered. The convective heat transfer coefficient decreases monotonically from the initial point of the thermal boundary layer, and then remains a constant value in the fully developed section.

[0045] According to the definition of Prandtl number (Pr) in heat transfer: ; Among them, ν is the viscosity coefficient, α is the thermal diffusion coefficient; the Pr number characterizes the relative strength relationship between momentum diffusion and thermal diffusion. The Pr number of water is about 6, and the Pr number of common coolants is about 54, indicating that when using water or common coolants as the medium, the development of the flow boundary layer is much faster than the thermal boundary layer. The smaller friction coefficient of the fluid in the fully developed flow stage and the larger convection heat transfer coefficient in the initial heat stage can be used to design the flow length of the heat exchange channel.

[0046] The length of the initial section of laminar flow is X fd ,h and the thermal initial segment length X fd ,t can be calculated as follows: ; Among them, R eD is the Reynolds number, D his the hydraulic equivalent diameter of the channel.

[0047] The long side of the heat exchange area is equal to the channel length L f , the short side W of the heat exchange zone is approximately equal to the side length of the power device. Assuming the number of parallel slots in the heat exchange zone is n, there is a relationship between the short side W of the heat exchange zone and the slot width w, the tooth width t and the number of slots n: ; Usually, the length-to-width ratio of the heat exchange area (L f / W) is between 1.5 and 3, which can better balance the contradiction between the inlet section effect of the flow and the economical heat exchanger.

[0048] The expansion angle a of the first flow diversion area is equal to the contraction angle b of the second flow diversion area, and the expansion angle a and the contraction angle b are 45° to 90°.

[0049] The central rectifying body 8 includes a straight edge section parallel to the flow axis and semicircular surfaces arranged at both ends of the straight edge section.

[0050] Sub-rectifier bodies 9 are arranged at intervals on both sides of the central rectifying body 8 . The sub-rectifier bodies 9 are arranged in parallel with the central rectifying body 8 or in a circular arc-shaped concentric radial arrangement.

[0051] In one embodiment, please refer to Figure 2 As shown, when the auxiliary rectifier 9 is arranged in parallel with the central rectifier 8, the length of the auxiliary rectifier 9 gradually decreases in the direction away from the central rectifier 8, and the end of the auxiliary rectifier 9 facing the heat exchange area 2 is flush with the end of the central rectifier 8 facing the heat exchange area 2, and the spacing between the rectifiers (that is, between the aforementioned central rectifier 8 and the aforementioned auxiliary rectifier 9 and between two adjacent auxiliary rectifiers 9) is equal or increases from the center to both sides.

[0052] In addition, in another embodiment, please refer to Figure 3 As shown, when the auxiliary rectifier body 9 and the central rectifier body 8 are arranged concentrically and radially in an arc shape, the length of the central rectifier body 8 in the radial direction is greater than the length of the auxiliary rectifier body 9, and the end of the auxiliary rectifier body 9 close to the heat exchange area 2 and the end of the central rectifier body 8 close to the heat exchange area 2 are on the same arc line; adjacent rectifier bodies (that is, between the aforementioned central rectifier body 8 and the aforementioned auxiliary rectifier body 9 and between two adjacent auxiliary rectifier bodies 9) are arranged at equal intervals, and the minimum angle between adjacent rectifier bodies is 15°.

[0053] In summary, the upstream structure and downstream structure of the planar heat exchanger proposed in the present invention have exactly the same geometric design, and the inlet and outlet are centered relative to the flow axis. In order to balance the contradiction between flow function and structural compactness, the expansion angle a (or contraction angle b) of the upstream structure (or downstream structure) is between 45° and 90°. In the upstream structure (or downstream structure), there is a rectifying mechanism at the center of the flow axis. Since the cylinder only has a disturbing effect but no rectifying effect, the central rectifying body 8 is a long cylinder, that is, it has a straight edge parallel to the flow axis, and the two ends of the straight edges on both sides are connected by semicircles. The semicircular end can better disturb the flow without forming a wake vortex, and the straight section parallel to the flow axis can complete the flow diversion. There is a distance between the central rectifying body 8 and the inlet (or outlet) of the planar heat exchanger and the parallel groove of the heat exchange zone 2. When acting as a diffuser, the distance between the front edge of the central rectifying body 8 and the diffuser inlet cross section will not hinder the flow, and the fluid is smoothly and symmetrically divided into two left and right streams; the distance between the rear edge of the central rectifying body 8 and the parallel grooves of the heat exchange flow area 2 allows the fluid to quickly merge into one stream after leaving the rear edge of the rectifying body, and be evenly distributed to the entrances of all parallel grooves. When acting as a nozzle, the central rectifying body 8 only plays a role in disturbing the flow, which will slightly increase the flow resistance.

[0054] If the parallel scale of the slots is large (for example, cooling devices with larger geometric dimensions, such as commercial CPUs, GPUs, or FPGAs), then in the upstream structure (or downstream structure), in addition to the central rectifier 8, multiple auxiliary rectifiers 9 can be symmetrically added on both sides.

[0055] The existence of the rectifying mechanism greatly reduces the span of the cavity area of ​​the upstream structure (or downstream structure), and greatly enhances the structural compressive strength of the area.

[0056] The length of the heat exchanger L is determined by the length of the heat exchange zone L f The heat exchanger is composed of three sections: the upstream structure length and the downstream structure length. The width W of the heat exchanger is equal to the short side of the heat exchange area. The contour turning point of the heat exchanger is designed with rounded corners.

[0057] The planar heat exchanger proposed in the present invention is composed of two parts, a box body 10 and a cover plate 11, which are connected as a whole by welding. The box body 10 includes the complete flow channel contour and all rectifiers of the heat exchanger composed of the first diversion area 1, the heat exchange area 2 and the second diversion area 3, and the cover plate 11 includes all the regularly arranged heat dissipation teeth 12 of the heat exchanger. The welding positioning of the two parts is achieved by specially designing two positioning columns 14-positioning holes 13, and the distance between the two positioning columns 14-positioning holes 13 is as large as possible to increase the linear positioning accuracy. The positioning column 14 is assigned to the cover plate 11, and a cylindrical design that is easier to achieve high processing accuracy is adopted; while the positioning hole 13 is assigned to the box body 10, and a cylindrical hole design that is easier to achieve high processing accuracy is adopted. The positioning column 14 on the cover plate 11 is the same height as the heat dissipation tooth 12 to save materials, and the distribution position cannot interfere with the tool path when processing the heat dissipation tooth 12.

[0058] The symmetrical direct-flow heat exchanger proposed in the present invention can be integrated into a variety of unit flow paths and dedicated liquid cooling plates, effectively solving the heat dissipation problem of high heat flux density and high-power electronic modules with typical non-uniform and distributed point heat source characteristics.

[0059] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A planar heat exchanger with interchangeable flow directions, characterized in that: The first flow diversion area (1), the heat exchange area (2) and the second flow diversion area (3) are sequentially connected; the first flow diversion area (1) and the second flow diversion area (3) are arranged in a mirror-symmetrical manner relative to the heat exchange area (2) and have completely the same geometric profile; The heat exchange area (2) is rectangular and is formed by a plurality of grooves and teeth parallel to the flow axis and arranged regularly at intervals; The first flow splitting area (1) and the second flow splitting area (3) are both planar variable cross-section flow channels, the widest cross-section end is connected to the heat exchange area (2), and the narrowest cross-section end is connected to the fluid inlet or outlet, and the fluid inlet or outlet is centrally located relative to the flow axis; in the first flow splitting area (1) and the second flow splitting area (3), there is a central rectifying body (8) at the center of the flow axis, and there is a distance between the central rectifying body (8) and the fluid inlet or outlet and the parallel channels of the heat exchange area (2); When the fluid flows through the first flow diversion area (1), the heat exchange area (2) and the second flow diversion area (3) in sequence, the first flow diversion area (1) behaves as a diffuser and the second flow diversion area (3) behaves as a nozzle; when the fluid flows through the second flow diversion area (3), the heat exchange area (2) and the first flow diversion area (1) in reverse order, the second flow diversion area (3) behaves as a diffuser and the first flow diversion area (1) behaves as a nozzle.

2. A planar heat exchanger with interchangeable flow directions according to claim 1, characterized in that: The expansion angle a of the first flow diversion area (1) is equal to the contraction angle b of the second flow diversion area (3), and the expansion angle a and the contraction angle b are between 45° and 90°.

3. The planar heat exchanger with interchangeable flow directions according to claim 1, characterized in that: The central rectifying body (8) is a long cylindrical body, comprising a straight edge section parallel to the flow axis and semicircular surfaces arranged at both ends of the straight edge section.

4. A planar heat exchanger with interchangeable flow directions according to any one of claims 1 to 3, characterized in that: The size of the planar heat exchanger with interchangeable flow directions increases or decreases according to the area of ​​the heat source to be cooled. After the planar heat exchanger with interchangeable flow directions is enlarged, in the first flow branch area (1) and the second flow branch area (3), a plurality of long cylindrical auxiliary flow branches (9) are symmetrically and spaced apart on both sides of the central flow branch (8), and the auxiliary flow branches (9) are arranged in parallel with the central flow branch (8) or in a circular arc-shaped concentric radial arrangement.

5. The planar heat exchanger with interchangeable flow directions according to claim 4, characterized in that: When the auxiliary rectifier (9) is arranged in parallel with the central rectifier (8), the length of the auxiliary rectifier (9) gradually decreases in the direction away from the central rectifier (8), and one end of the auxiliary rectifier (9) facing the heat exchange area (2) is flush with one end of the central rectifier (8) facing the heat exchange area (2), and the spacing between the rectifiers is equal or increases from the center to both sides.

6. The planar heat exchanger with interchangeable flow directions according to claim 4, characterized in that: When the auxiliary rectifier (9) and the central rectifier (8) are arranged concentrically and radially in an arc shape, the length of the central rectifier (8) in the radial direction is greater than the length of the auxiliary rectifier (9), and the auxiliary rectifiers (9) are of the same size, and one end of the auxiliary rectifier (9) close to the heat exchange area (2) and one end of the central rectifier (8) close to the heat exchange area (2) are on the same virtual arc line; adjacent rectifiers are arranged at equal intervals.

7. A planar heat exchanger with interchangeable flow directions according to claim 6, characterized in that: The central rectifier (8) and the auxiliary rectifier (9) are arranged concentrically and radially in an arc shape, and the minimum angle between adjacent rectifiers is 15°.

8. The planar heat exchanger with interchangeable flow directions according to claim 4, characterized in that: The grooves in the heat exchange zone (2) are straight grooves with equal cross-sections, and the tooth plates are straight tooth plates with equal cross-sections. The characteristic size and number of the grooves are independent of the size of the heat source area and are only determined by the size of the heat flux density of the heat source.

9. A planar heat exchanger with interchangeable flow directions according to any one of claim 1, characterized in that: It consists of two parts, a box body (10) and a cover plate (11), which are connected as a whole by welding. The welding positioning of the two parts is achieved by the cooperation of a group of positioning columns (14) and positioning holes (13).

10. The planar heat exchanger with interchangeable flow directions according to claim 9, characterized in that: The box body (10) comprises a complete flow channel profile formed by a first flow distribution area (1), a heat exchange area (2) and a second flow distribution area (3), a central rectifying body (8), an auxiliary rectifying body (9) and a group of positioning holes (13); the cover plate (11) comprises all heat dissipation teeth of the heat exchange area (2) and a group of positioning columns (14).

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