Three-dimensional interlaced micro-channel SiC ceramic heat exchanger and preparation method thereof

Abstract

The application belongs to the technical field of ceramic material forming and heat exchange, and particularly discloses a three-dimensional staggered micro-channel SiC ceramic heat exchanger and a preparation method thereof. The three-dimensional staggered micro-channel SiC ceramic heat exchanger comprises cold working medium micro-channels and hot working medium micro-channels, and the initial Gyroid lattice structure is offset by 1 / 2 of the period length along the X-axis, the Y-axis and the Z-axis direction. The initial Gyroid lattice structure and the Gyroid lattice structure offset along the Y-axis direction jointly form the cold working medium micro-channels, and the Gyroid lattice structure offset along the X-axis and the Z-axis direction jointly form the hot working medium micro-channels. The cold working medium micro-channels and the hot working medium micro-channels are chiral and embedded with each other and are physically isolated from each other. The three-dimensional staggered micro-channels are constructed, in which the cold working medium and the hot working medium are adjacent and staggered. Higher space utilization and specific surface area are realized, the heat exchanger has a compact structure and a significantly enhanced heat exchange performance, and the heat exchange area in a unit volume is effectively increased and the heat exchange performance is enhanced.

Description

Technical Field

[0001] This invention relates to the field of ceramic material forming and heat exchange technology, and in particular to a three-dimensional staggered microchannel SiC ceramic heat exchanger and its preparation method. Background Technology

[0002] As thermal systems in cutting-edge technology fields such as advanced nuclear energy systems, aerospace propulsion systems, and high-power electronic devices develop towards higher temperatures (>1000 ℃), higher heat flux densities, and more compact volumes, traditional heat exchangers face severe challenges in terms of high temperature resistance, structural compactness, and heat exchange performance, and urgently need to achieve innovative breakthroughs in heat exchanger structural design and manufacturing processes.

[0003] Microchannel heat exchangers, due to their tiny channel size (<1 mm) and extremely high heat transfer area (an order of magnitude higher than traditional heat exchangers), have shown significant potential in reducing system volume and improving heat transfer performance. However, existing microchannel heat exchangers are mainly based on flat or tube bundle two-dimensional stacked structures, such as the schemes disclosed in CN110425904A and CN221666688U, which have the following limitations: (1) The arrangement of microchannels is limited by the two-dimensional spatial extension, resulting in low three-dimensional space utilization and a limited effective heat transfer area that can be constructed per unit volume; (2) The mainstream direction of the working fluid in the stacked structure is almost perpendicular to the temperature gradient direction, resulting in poor flow and heat transfer matching and limited heat transfer performance; (3) There are a large number of interfaces in the stack, which are prone to becoming crack sources under high thermal stress and load, leading to interlayer leakage or structural failure. In addition, most existing microchannel heat exchangers are made of metal materials, and metals have significant performance bottlenecks in extreme high temperature and strong corrosion environments: conventional stainless steel is prone to oxide scale peeling and grain boundary corrosion above 650 ℃; although nickel-based alloys can withstand high temperatures of about 900 ℃, they are prone to embrittlement in sulfidation or environments containing corrosive impurities, accompanied by carbide precipitation, microstructure degradation and decreased mechanical properties.

[0004] In contrast, silicon carbide (SiC) ceramic materials are considered ideal for high-temperature microchannel heat exchangers due to their advantages such as high temperature resistance, corrosion resistance, and high specific strength. However, their high melting point and high hardness and brittleness make it difficult to achieve the complex three-dimensional microchannel structure forming for enhanced heat transfer using traditional machining methods, severely limiting the engineering application of microchannel ceramic heat exchangers. Therefore, a new structural design and integral forming process is urgently needed to achieve a performance breakthrough in microchannel heat exchangers. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned shortcomings of existing technologies by providing a three-dimensional staggered microchannel SiC ceramic heat exchanger and its fabrication method. The three-dimensional staggered microchannel structure overcomes the space utilization limitations of traditional two-dimensional stacked structures, allowing the microchannels to be arranged in a staggered manner in three-dimensional space, thereby significantly increasing the specific surface area per unit volume, up to a maximum of 10300 m². 2 / m 3 This structure also allows for a better match between the working fluid flow direction and the temperature gradient direction, enhancing convective heat transfer and achieving a volumetric power density exceeding 100 MW / m³. 3 Furthermore, the integral forming of SiC ceramics without interlayer interfaces significantly improves structural reliability under high heat flux density and high temperature loads.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of this invention is to provide a three-dimensional staggered microchannel SiC ceramic heat exchanger, comprising: a heat exchanger body, composed of an array of multiple unit cells, each unit cell being composed of four interlocking Gyroid lattice structures; the four Gyroid lattice structures include an initial lattice structure G1 and offset lattice structures G2, G3, and G4; G2, G3, and G4 are respectively offset from G1 along the X-axis, Y-axis, and Z-axis directions by half of their period length, G1 and G3 together constitute a cold working medium microchannel, and G2 and G4 together constitute a hot working medium microchannel, wherein G1 is defined by Equation 1, and G2, G3, and G4 are defined by Equations 2, 3, and 4 respectively.

[0008] Formula 1;

[0009] Formula 2; Formula 3; Equation 4;

[0010] Where C is a parameter, l is the period length, and α is the structural deformation coefficient, with a value of 0.5~1.5;

[0011] The cold working medium microchannel and the hot working medium microchannel are chirally interlocked and physically isolated from each other, constructing a three-dimensional staggered microchannel in which the cold and hot working mediums are adjacent to each other and distributed alternately.

[0012] Furthermore, the heat exchange area of ​​the three-dimensional staggered microchannel SiC ceramic heat exchanger reaches 7400~10300m². 2 / m 3 Volumetric power density reaches 100~350 MW / m 3 .

[0013] Furthermore, it also includes a first distributor and a second distributor respectively disposed at both ends of the heat exchanger body, the first distributor being connected to the first inlet pipe and the first outlet pipe respectively, and the second distributor being connected to the second inlet pipe and the second outlet pipe respectively.

[0014] Furthermore, both the first and second splitters include:

[0015] The multi-port has a first port for introducing cold working fluid at one end and a second port for introducing hot working fluid at the other end.

[0016] The main body interface is located between the first interface and the second interface, and is sealed and connected to the end face of the heat exchanger body;

[0017] The internal isolation structure includes multiple horizontally arranged internal baffles; the multiple internal baffles divide the internal space of the distributor into multiple sub-chambers; the sub-chambers in the first distributor are connected only to the cold working fluid microchannels, and the sub-chambers in the second distributor are connected only to the hot working fluid microchannels, for forming a three-dimensional staggered distribution and collection of cold and hot working fluids at the inlet and outlet positions of the heat exchanger body.

[0018] Furthermore, the first inlet pipe, the first outlet pipe, the second inlet pipe, and the second outlet pipe are all tapered transition pipe structures that gradually expand from a round opening to a square opening.

[0019] A second aspect of the present invention is to provide a method for preparing the aforementioned three-dimensional staggered microchannel SiC ceramic heat exchanger, comprising the following steps:

[0020] The structural templates of the cold working medium microchannels and hot working medium microchannels are designed according to the structure of the described structure, and are formed by photopolymerization 3D printing using resin as raw material.

[0021] A water-based SiC ceramic slurry was prepared and injected into the structural template under vacuum pressure.

[0022] SiC ceramic preforms are formed by cryogel solidification and then freeze-dried to obtain SiC ceramic blanks;

[0023] The SiC ceramic blank is thermally degreased and demolded to obtain a preform, which is then subjected to high-temperature silicon infiltration sintering to obtain an integrally formed microchannel core.

[0024] Furthermore, the water-based SiC ceramic slurry comprises: 60%~70% SiC powder by volume, 0.5%~1.5% polyvinyl alcohol by mass, and 0.2%~0.5% tetramethylammonium hydroxide by mass.

[0025] Furthermore, the gel curing temperature is -5℃ to -40℃, and the curing time is 1 to 4 hours.

[0026] Furthermore, the heat-induced degreasing and demolding process involves raising the temperature from room temperature to 600℃~650℃ at a heating rate of 0.5℃ / min and holding it at that temperature for 2~3 hours.

[0027] Furthermore, the high-temperature silicon infiltration sintering is carried out using a liquid-phase followed by gas-phase silicon infiltration method, specifically including: embedding the preform in silicon powder and placing it in a vacuum sintering furnace, raising the temperature from room temperature to 1400℃~1450℃ at a heating rate of 5℃~10℃ / min and holding it at that temperature for 2~2.5h, so that liquid-phase silicon infiltrates into the preform; then continuing to raise the temperature to 1700~1750℃ at a heating rate of 5~10℃ / min and holding it at that temperature for 1~1.5h.

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] (1) The present invention provides a three-dimensional staggered microchannel SiC ceramic heat exchanger composed of multiple unit cell arrays, each unit cell being composed of four Gyroid lattice structures spatially interlocked; the four Gyroid lattice structures include an initial lattice structure G1 and offset lattice structures G2, G3, and G4; G2, G3, and G4 are respectively offset by half of their period length along the X-axis, Y-axis, and Z-axis directions with G1 as the reference. The four Gyroid lattice structures are intertwined in the unit cell space and do not interfere with each other, thereby forming four independent fluid domain channels inside the heat exchanger. G1 and G3 together constitute a cold working medium microchannel, and G2 and G4 together constitute a hot working medium microchannel, effectively increasing the heat exchange area per unit volume and enhancing the heat exchange performance.

[0030] (2) By nesting porous lattice structures in three-dimensional space, a three-dimensional staggered microchannel is constructed in which cold and hot working fluids are adjacent to each other and distributed in an alternating manner, thereby achieving higher space utilization and specific surface area. This allows the heat exchanger to achieve significantly enhanced heat transfer performance while maintaining a compact design, with a volumetric power density exceeding 100 MW / m³. 3 .

[0031] (3) Complex three-dimensional interlaced microchannels are prepared by integral molding process, which avoids the interface problems of easy leakage and damage in traditional stacked structures, and significantly improves structural integrity and service reliability. The prepared three-dimensional interlaced microchannel ceramic heat exchanger can achieve a density of 95% to 98% and a bending strength of 200 to 300 MPa. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the three-dimensional staggered microchannel SiC ceramic heat exchanger structure in this invention;

[0033] Figure 2 This is a schematic diagram of the main structure of the three-dimensional staggered microchannel heat exchanger in this invention;

[0034] Figure 3 The heat transfer area corresponding to different deformation coefficients of the three-dimensional staggered microchannel SiC ceramic heat exchanger in this invention;

[0035] Figure 4 This is a flow diagram of the cold and hot working fluids inside the three-dimensional staggered microchannel SiC ceramic heat exchanger of the present invention;

[0036] Figure 5 This is a statistical diagram of the particle size distribution of SiC powder used in this invention;

[0037] Figure 6 The images show the physical structure (a and b) of the three-dimensional staggered microchannel SiC ceramic heat exchanger in Example 1 and its microstructure (c and d).

[0038] Figure 7 A performance comparison diagram of a traditional microchannel heat exchanger and the SiC ceramic heat exchanger of the present invention;

[0039] In the picture:

[0040] 101-First Inlet Pipe

[0041] 102-Second Inlet Pipe

[0042] 201-First Outlet Pipe

[0043] 202-Second Outlet Pipe

[0044] 401 - Heat exchanger body

[0045] 402-unit cell,

[0046] 403 - End face of heat exchanger body

[0047] 310 - First shunt

[0048] 320 - Second shunt

[0049] 301 - First Interface

[0050] 302-Second Interface

[0051] 303-Inner partition,

[0052] 304-sub-chamber. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of this invention clearer, the specific embodiments and accompanying drawings are described in further detail below. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0054] Terminology Explanation:

[0055] The "Gyroid-type lattice structure" in this invention is a continuous non-self-intersecting surface structure defined by the interweaving of sine and cosine functions, based on the mathematical theory of three-period minimum surfaces (TPMS), and has highly connected spatial topological characteristics.

[0056] In this invention, "asymmetric expanding configuration at both ends" refers to a specific geometric shape feature of the splitter. "Asymmetric" means that the single-port cross-section (usually circular or rectangular) at the feed end of the splitter differs significantly in geometric topology and the number of openings from the lattice-type porous interface at the docking end; "expanding" means that the envelope profile of the splitter smoothly expands along the fluid flow direction to achieve fluid deceleration, pressure stabilization, and flow field spreading.

[0057] In this invention, "internal baffle and sub-chamber" refers to: an internal baffle, which is a physical partition component arranged horizontally or in a specific radial parallel arrangement inside the distributor; and a sub-chamber, which is a plurality of thin-layered independent pressure chambers formed by the internal baffle dividing the internal volume of the distributor. Its function is to decouple the macroscopic continuous fluid into multiple parallel tiered flow streams in the vertical dimension before it enters the heat exchanger body.

[0058] In this invention, "matrix-shaped flow-through micro-orifices" refers to the discretely distributed micro-fluid channel interfaces on the interface face of the splitter. Their arrangement is no longer a single opening, but rather spatially encoded according to the topological phase of the heat exchanger's main body end face. The flow-through micro-orifices corresponding to the sub-chambers are staggered on the end face (like a checkerboard pattern), serving as the key physical interface for realizing the transformation of fluid from "laminar flow" to "three-dimensional staggered flow."

[0059] Example 1

[0060] This invention provides a three-dimensional staggered microchannel SiC ceramic heat exchanger, employing an integrated additive manufacturing structure. (Reference) Figure 1 and Figure 2 The heat exchanger includes:

[0061] The heat exchanger body 401 is composed of multiple unit cells 402 arranged in an array in three-dimensional space;

[0062] It is composed of multiple unit cell arrays, each unit cell being formed by four Gyroid-type lattice structures spatially interlocked; the four Gyroid-type lattice structures include an initial lattice structure G1 and offset lattice structures G2, G3, and G4; G2, G3, and G4 are respectively obtained by offsetting half of their period length along the X-axis, Y-axis, and Z-axis directions, with G1 as the reference. G1 and G3 together constitute a cold working fluid microchannel, and G2 and G4 together constitute a hot working fluid microchannel. G1 is defined by Equation 1, and G2, G3, and G4 are defined by Equations 2, 3, and 4, respectively.

[0063] Formula 1;

[0064] Formula 2; Formula 3; Equation 4;

[0065] Where C is a parameter, l is the period length, and α is the structural deformation coefficient, which takes a value of 0.5 to 1.5;

[0066] The cold working medium microchannel and the hot working medium microchannel are chirally interlocked and physically isolated from each other, constructing a three-dimensional staggered microchannel in which the cold and hot working mediums are adjacent to each other and distributed alternately.

[0067] refer to Figure 3 The structural variation coefficient α is in the range of 0.5 to 1.5, and the three-dimensional staggered microchannel configuration enables the heat exchanger to achieve a heat exchange area of ​​7400 to 10300 m². 2 / m 3 Volumetric power density reaches 100~350 MW / m 3 .

[0068] refer to Figure 4 This figure reveals the flow field dynamics within a three-dimensional staggered microchannel through computational fluid dynamics simulation: at local flow velocities up to 120 m / s, the Gyroid-type triple-periodic minimal surface geometry forces the fluid to generate intense secondary flows and vortices (indicated by red arrows in the figure). This intense fluid disturbance effectively thins the laminar boundary layer (the main source of thermal resistance) by scouring the walls and promotes deep mixing of hot and cold fluids, explaining the physical mechanism behind the structure's ultra-high volumetric heat transfer density.

[0069] In some embodiments, a first distributor 310 and a second distributor 320 are respectively disposed at both ends of the heat exchanger body 401. The first distributor 310 is connected to the first inlet pipe 101 and the first outlet pipe 201, respectively, and the second distributor 320 is connected to the second inlet pipe 102 and the second outlet pipe 202, respectively.

[0070] The separator is the core component for converting macroscopic fluid into microscopic array flow. It can be designed as a two-section asymmetric, gradually expanding configuration with an internal stacked isolation structure. The separator shell presents an irregularly shaped cavity that smoothly expands from the near end to the far end (connecting to the heat exchanger body). Static pressure recovery is achieved through expansion and deceleration, ensuring uniform distribution of the hot and cold working fluids before entering the heat exchanger body. Specifically, both the first separator 310 and the second separator 320 include:

[0071] The multi-port has a first port 301 for introducing cold working fluid at one end and a second port 302 for introducing hot working fluid at the other end.

[0072] The main body interface 305 is located between the first interface and the second interface, and is sealed and connected to the end face of the heat exchanger body;

[0073] The internal isolation structure includes multiple horizontally arranged internal baffles 303; the multiple internal baffles 303 divide the internal space of the distributor into multiple sub-chambers 304; the sub-chambers in the first distributor are connected only to the cold working fluid microchannels, and the sub-chambers in the second distributor are connected only to the hot working fluid microchannels, for forming a three-dimensional staggered distribution and collection of cold and hot working fluids at the inlet and outlet positions of the heat exchanger body.

[0074] Taking the first splitter 310 as an example, its opposite ends are respectively introduced into the cold and hot working fluids by the first inlet pipe 101 and the second inlet pipe 201. The inner baffle guides the cold working fluid to the sub-chamber and the hot working fluid to another sub-chamber, realizing the layered arrangement of cold and hot fluids in the same component.

[0075] The main body of the splitter is sealed and connected to the end face 403 of the heat exchanger body. The cold and hot working fluids enter the splitter in the form of continuous single-phase flow. They are cut into thin-layered parallel flow streams by the inner baffle. Then, the flow streams are transformed into point source flow with lattice distribution through the unit cell, and a three-dimensional staggered flow field without interference is constructed in the heat exchanger body, thereby realizing the independent flow and heat exchange of the two working fluids in space.

[0076] The heat exchanger provided by this invention operates as follows: cold and hot working fluids are introduced through the first and second inlet pipes, respectively. When the high-speed flowing working fluid enters the chamber of the distributor, the horizontally arranged internal baffles precisely divide the distributor volume into multiple fluid-isolated sub-chambers in the vertical direction. The originally single flow channel is transformed into a "layered" multi-stage parallel flow channel. The internal baffles guide the cold working fluid to one sub-chamber and the hot working fluid to another, achieving a layered arrangement of cold and hot fluids within the same component. When the fluid flows from the sub-chamber to the end face of the heat exchanger body, the main interface of the distributor and the Gyroid microchannel openings within the heat exchanger body are topologically conformally connected, discretized into thousands of tiny lattice flow streams. This design allows for a three-dimensional, staggered distribution and convergence of the cold and hot working fluids at the instantaneous interface upon entering the heat exchanger body. After entering the heat exchanger body, the working fluids flow within four independent Gyroid-type lattice structures (G1, G2, G3, and G4) without mixing. Due to the triple-periodic connectivity and non-coplanar staggered central axes of the Gyroid-type lattice structure, the cold and hot working fluid streams exhibit omnidirectional spiral interweaving and flow around the fluid in space. The fluids in the continuously tortuous channels not only possess a large heat transfer surface area but also generate intense secondary flow vortices. These vortices continuously break up the thermal resistance boundary layer, significantly enhancing the convective heat transfer coefficient. Heat is rapidly transferred from the hot-side working fluid to the cold-side working fluid through the highly thermally conductive, minimally curved thin walls, while perfect physical isolation ensures that the two working fluids never mix throughout the entire three-dimensional interweaving process. Finally, the arrayed microfluids, having completed heat exchange, reach the outlet end of the heat exchanger body. The outlet-side distributors execute the reverse logic, symmetrical to the inlet-side distributors, and discharge through their respective outlets. The heat exchanger of this invention utilizes a quadruple-interlocking topology to achieve high-rate, low-loss heat exchange between multiple working fluids while ensuring complete physical isolation of the fluids, through extremely high surface area density and fluid disturbance characteristics.

[0077] Example 2

[0078] The inlet and outlet pipes of this three-dimensional staggered microchannel SiC heat exchanger both adopt a tapered transition pipe structure that gradually expands from a round opening to a square opening. The inlet and outlet pipes are connected to both ends of the microchannel core through a flow distribution cavity. The microchannel core internally employs a Gyroid-type lattice structure, nested in three-dimensional space to form a three-dimensional staggered microchannel configuration. The Gyroid-type lattice structure has a porosity of 86%, an equivalent pore diameter of 0.5 mm, and a deformation coefficient α of 1.5. The heat transfer area per unit volume of this microchannel core is approximately 10300 m². 2 / m 3 Volumetric power density can reach 350 MW / m 3 The heat exchanger is manufactured according to the following steps:

[0079] (1) A photocurable resin molding mold is used, and the surface of the resin molding mold is subjected to atomized coating treatment. The surface atomized coating treatment adopts the paraffin emulsion atomization spraying method, and a surface film is formed by the evaporation of water solvent to eliminate the surface staircase effect of 3D printing. In this embodiment, the resin can be a commercially available wax-like photosensitive resin, such as, but not limited to: Formlabs Castable Wax, Somos Element, or industrial-grade casting resin with equivalent properties. It is sufficient that it can completely decompose before the high-temperature sintering stage and does not chemically react with the heat exchanger body material.

[0080] (2) SiC powders with particle sizes of 30 μm, 7 μm, and 0.5 μm were selected and mixed in a mass ratio of 11:5:4. A water-based SiC ceramic slurry was prepared using polyvinyl alcohol as a binder and tetramethylammonium hydroxide as a dispersant. The volume fraction of the ceramic powder was 70%, the mass fraction of the binder was 1.5%, and the mass fraction of the dispersant was 0.5%. The SiC powder was commercially available α-SiC powder. The particle size distribution is shown in the figure below. Figure 5 As shown.

[0081] (3) After the prepared ceramic slurry was placed in a vacuum environment of -0.095 MPa for 8 min, it was injected into a resin molding mold under a pressure of 0.5 MPa and gelled and cured at -40 ℃ for 1 h to form a blank; then the blank was obtained by freeze drying.

[0082] (4) The preform was heated from room temperature to 650 ℃ at a heating rate of 0.5 ℃ / min and held for 2 h to perform low-temperature thermal degreasing and demolding treatment to obtain the preform. The preform was then embedded in silicon powder and placed in a vacuum sintering furnace. The temperature was increased from room temperature to 1450 ℃ at a heating rate of 10 ℃ / min and held for 2 h to allow liquid silicon to penetrate into the preform. The temperature was then increased to 1750 ℃ ​​at a heating rate of 10 ℃ / min to remove free silicon inside the microchannels using high-temperature vaporization of silicon, and held for 1 h. Finally, the furnace was cooled to room temperature to obtain a three-dimensional staggered microchannel SiC ceramic heat exchanger with a density of 98% and a flexural strength of 280 MPa.

[0083] Example 3

[0084] The inlet and outlet pipes of this three-dimensional staggered microchannel SiC heat exchanger both adopt a tapered transition pipe structure that gradually expands from a round opening to a square opening. The inlet and outlet pipes are connected to both ends of the microchannel core through a flow divider. The microchannel core internally employs a Gyroid-type lattice structure, nested in three-dimensional space to form a three-dimensional staggered microchannel configuration. The Gyroid-type lattice structure has a porosity of 98%, an equivalent pore diameter of 0.2 mm, and a deformation coefficient α of 0.5. The heat transfer area per unit volume of this microchannel core is approximately 7400 m². 2 / m 3 Volumetric power density can reach 100 MW / m 3 The heat exchanger is manufactured according to the following steps:

[0085] (1) A photocurable resin molding mold is used, and the surface of the resin molding mold is subjected to atomized coating treatment. The surface atomization coating treatment adopts the paraffin emulsion atomization spraying method, and a surface film is formed by the evaporation of water solvent to eliminate the surface step effect of 3D printing. In this embodiment, the resin can be a commercially available wax-like photosensitive resin, such as, but not limited to: Formlabs Castable Wax, Somos Element, or industrial-grade casting resin with equivalent properties. It is acceptable if it can completely decompose before the high-temperature sintering stage and does not chemically react with the heat exchanger body material.

[0086] (2) Select SiC powders with particle sizes of 30 μm, 7 μm and 0.5 μm respectively, and mix them in a mass ratio of 11:5:4; use polyvinyl alcohol as binder and tetramethylammonium hydroxide as dispersant to prepare water-based SiC ceramic slurry, wherein the volume fraction of ceramic powder is 60%, the mass fraction of binder is 0.5% and the mass fraction of dispersant is 0.2%.

[0087] (3) After the prepared ceramic slurry was placed in a vacuum environment of −0.08 MPa for 3 min, it was injected into a resin molding mold under a pressure of 0.2 MPa and then frozen and cured at −5 ℃ for 4 h to form a blank; subsequently, the blank was obtained by freeze drying.

[0088] (4) The preform was heated from room temperature to 650 ℃ at a heating rate of 0.5 ℃ / min and held for 2 h to perform low-temperature thermal degreasing and demolding treatment to obtain the preform. The preform was then embedded in silicon powder and placed in a vacuum sintering furnace. The temperature was increased from room temperature to 1450 ℃ at a heating rate of 10 ℃ / min and held for 2 h to allow liquid silicon to penetrate into the preform. The temperature was then increased to 1750 ℃ ​​at a heating rate of 10 ℃ / min to remove free silicon inside the microchannels using high-temperature vaporization of silicon, and held for 1 h. Finally, the furnace was cooled to room temperature to obtain a three-dimensional staggered microchannel SiC ceramic heat exchanger with a density of 95% and a flexural strength of 200 MPa.

[0089] refer to Figure 6 The figure shows the actual SiC ceramic heat exchanger and its microstructure prepared by 3D printing and reaction sintering technology in Example 1: optical photographs of the actual object (shown in a and b in the figure). The sample adopts a complex Gyroid-type triple-period minimal surface structure, with a diameter of approximately 20×20×20 mm. 3 Extremely high heat transfer specific surface area is achieved within the volume; microscopically, as shown in SEM images (c and d in the figure), the dense SiC framework is tightly bonded to the filled silicon phase, providing excellent thermal conductivity and structural strength.

[0090] refer to Figure 7 A performance comparison of the three-dimensional staggered microchannel SiC ceramic heat exchanger of this invention with that of traditional ceramic heat exchangers (SiO2, Al2O3, SiC): The results show that, under the same pressure drop (Δp / L), the volumetric heat transfer density designed in this invention is 1 to 2 orders of magnitude higher than that of traditional equipment, with the highest exceeding 300 MW / m. 3 As the deformation coefficient α increases, the heat exchange capacity and pressure drop of the present invention increase simultaneously. This proves that the present invention achieves extreme miniaturization of the device while maintaining high-efficiency heat exchange, and significantly exceeds the performance limit of traditional ceramic microchannel heat exchangers in terms of thermodynamic performance.

[0091] For any points not covered above, existing technologies shall apply.

[0092] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A three-dimensional staggered microchannel SiC ceramic heat exchanger, characterized in that, include: The heat exchanger body is composed of multiple unit cell arrays, each unit cell consisting of four interlocking Gyroid lattice structures. The four Gyroid lattice structures include an initial lattice structure G1 and offset lattice structures G2, G3, and G4. G2, G3, and G4 are obtained by offsetting G1 along the X, Y, and Z axes by half its period length, respectively. G1 and G3 together form a cold working fluid microchannel, and G2 and G4 together form a hot working fluid microchannel. G1 is defined by Equation 1, and G2, G3, and G4 are defined by Equations 2, 3, and 4, respectively. Formula 1; Formula 2; Formula 3; Equation 4; Where C is a parameter, l is the period length, and α is the structural deformation coefficient, with a value of 0.5~1.5; The cold working medium microchannel and the hot working medium microchannel are chirally interlocked and physically isolated from each other, constructing a three-dimensional staggered microchannel in which the cold and hot working mediums are adjacent to each other and distributed alternately.

2. The three-dimensional staggered microchannel SiC ceramic heat exchanger according to claim 1, characterized in that, The heat exchange area of ​​the three-dimensional staggered microchannel SiC ceramic heat exchanger reaches 7400~10300 m². 2 / m 3 Volumetric power density reaches 100~350MW / m 3 .

3. The three-dimensional staggered microchannel SiC ceramic heat exchanger according to claim 1, characterized in that, It also includes a first distributor and a second distributor respectively disposed at both ends of the heat exchanger body. The first distributor is connected to the first inlet pipe and the first outlet pipe respectively, and the second distributor is connected to the second inlet pipe and the second outlet pipe respectively.

4. The three-dimensional staggered microchannel SiC ceramic heat exchanger according to claim 3, characterized in that, Both the first and second splitters include: The multi-port has a first port for introducing cold working fluid at one end and a second port for introducing hot working fluid at the other end. The main body interface is located between the first interface and the second interface, and is sealed and connected to the end face of the heat exchanger body; The internal isolation structure includes multiple horizontally arranged internal baffles; the multiple internal baffles divide the internal space of the distributor into multiple sub-chambers; the sub-chambers in the first distributor are connected only to the cold working fluid microchannels, and the sub-chambers in the second distributor are connected only to the hot working fluid microchannels, for forming a three-dimensional staggered distribution and collection of cold and hot working fluids at the inlet and outlet positions of the heat exchanger body.

5. The three-dimensional staggered microchannel SiC ceramic heat exchanger according to claim 4, characterized in that, The first inlet pipe, the first outlet pipe, the second inlet pipe, and the second outlet pipe are all tapered transition pipe structures that gradually expand from a round opening to a square opening.

6. A method for preparing the three-dimensional staggered microchannel SiC ceramic heat exchanger according to claim 1, characterized in that, Includes the following steps: The structural templates for the cold working medium microchannel and the hot working medium microchannel as described in claim 1 are designed and formed by photopolymerization 3D printing using resin as raw material. A water-based SiC ceramic slurry was prepared and injected into the structural template under vacuum pressure. SiC ceramic preforms are formed by cryogel solidification and then dried to obtain SiC ceramic blanks; The SiC ceramic blank is thermally degreased and demolded to obtain a preform, which is then subjected to high-temperature silicon infiltration sintering to obtain an integrally formed microchannel core.

7. The preparation method according to claim 6, characterized in that, The water-based SiC ceramic slurry comprises: 60% to 70% SiC powder by volume, 0.5% to 1.5% polyvinyl alcohol by mass, and 0.2% to 0.5% tetramethylammonium hydroxide by mass.

8. The preparation method according to claim 6, characterized in that, The gel curing temperature is -5℃ to -40℃, and the curing time is 1 to 4 hours.

9. The preparation method according to claim 6, characterized in that, The heat-induced degreasing and demolding process involves raising the temperature from room temperature to 600℃~650℃ at a rate of 0.5℃ / min and holding it at that temperature for 2~3 hours.

10. The preparation method according to claim 6, characterized in that, The high-temperature silicon infiltration sintering is carried out by first infiltrating the liquid phase and then the gas phase. Specifically, it includes: embedding the preform in silicon powder and placing it in a vacuum sintering furnace, raising the temperature from room temperature to 1400℃~1450℃ at a heating rate of 5℃~10℃ / min and holding it at that temperature for 2~2.5h, so that the liquid phase silicon infiltrates into the preform; then continuing to raise the temperature to 1700~1750℃ at a heating rate of 5~10℃ / min and holding it at that temperature for 1~1.5h.

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