Directional freezing device

Abstract

The utility model discloses a directional freezing device which comprises a heat insulation box. The heat conduction mold is arranged in the heat insulation box, a first curved-surface pipe wall and a second curved-surface pipe wall are spliced into a circular-pipe-shaped structure, and the heat conductivity coefficient of the first curved-surface pipe wall is lower than that of the second curved-surface pipe wall; the array salient points are arranged on the inner side surface of the second curved-surface pipe wall; the heat-insulating film is used for blocking the upper part and the lower part of the heat-conducting mold; one end of the guide pipe is located outside the heat insulation box, the other end of the guide pipe is located in the heat conduction mold between the upper heat insulation film and the lower heat insulation film, the guide pipe is used for filling ceramic slurry into the heat conduction mold between the heat insulation films, and the part between the two ends of the guide pipe penetrates through the circumferential wall of the lower portion of the heat conduction mold and the heat insulation film located on the lower portion; and the cooling assembly is arranged at the bottom or the top of the heat conduction mold and exchanges heat with the heat conduction mold. The device is simple in structure and low in cost, and can realize high-precision preparation of horizontal ordered pore channels in porous ceramics.

Description

directional refrigeration unit Technical Field

[0001] This utility model relates to the technical field of porous ceramic preparation apparatus, and in particular to a directional freezing apparatus for preparing porous ceramics. Background Technology

[0002] Traditional porous ceramic preparation requires the addition of organic or inorganic pore-forming agents, such as polyurethane foam or carbonates, to the ceramic slurry. After sintering, the ceramic slurry containing these pore-forming agents may retain impurities, affecting the purity of the material. Furthermore, when the pore-forming agents decompose during product use, they can produce harmful gases such as CO2 and NO3. - These do not meet green manufacturing standards.

[0003] In addition, directional pore formation using ice crystals is a common approach. Existing directional freezing devices mostly employ a vertical temperature gradient (with the cold source located at the bottom or top of the mold), causing ice crystals to grow vertically, forming vertical columnar channels. This fails to meet the application requirements for mass transfer and electrical conductivity in the horizontal direction. Furthermore, the pores obtained by existing directional ice crystal formation methods often exhibit uneven arrangement. This is because during vertical freezing, ice crystal growth is easily affected by gravity, leading to stratification or distortion, and disordered channel arrangement, resulting in significant anisotropy of the material's mechanical properties. Simultaneously, some high-end directional freezing devices rely on vacuum freeze-drying or laser-assisted solidification technologies, which are costly and complex to operate, making them difficult to promote in industrial settings.

[0004] Therefore, how to provide a low-cost directional freezing device for preparing porous ceramics with horizontally ordered pore structures is an urgent technical problem to be solved. Summary of the Invention

[0005] To address the technical problem that existing devices for preparing porous ceramics with horizontally ordered pore structures rely on expensive, high-end directional freezing equipment, this invention proposes a directional freezing device.

[0006] The directional freezing device proposed in this utility model includes:

[0007] Insulated box;

[0008] A thermally conductive mold is set in a heat-insulating box. It is a circular tube structure spliced ​​together by a first curved tube wall and a second curved tube wall, and the thermal conductivity of the first curved tube wall is lower than that of the second curved tube wall.

[0009] An array of protrusions is provided on the inner surface of the second curved tube wall;

[0010] Heat insulation film, used to seal the upper and lower parts of heat-conducting molds;

[0011] The conduit has one end located outside the heat insulation box and the other end located inside the heat-conducting mold between the upper and lower heat insulation films. It is used to fill the heat-conducting mold between the heat insulation films with ceramic slurry. The part between the two ends of the conduit passes through the lower circumferential wall of the heat-conducting mold and the lower heat insulation film.

[0012] Cooling components are located at the bottom or top of the heat-conducting mold and exchange heat with it.

[0013] Furthermore, the cross-sections of the first curved tube wall and the second curved tube wall perpendicular to the axis of the heat-conducting mold are semi-circular, and the boundary between the first curved tube wall and the second curved tube wall is parallel to the central axis of the heat-conducting mold.

[0014] Furthermore, the first curved tube wall is made of organic material, while the second curved tube wall is made of copper, aluminum, or glass.

[0015] Furthermore, the spacing between adjacent bumps in the array is 1-100µm.

[0016] Furthermore, the bumps in the array are cone-shaped.

[0017] Furthermore, the cooling assembly includes a cold plate supported at the bottom of the heat-conducting mold and a cold source that exchanges heat with the cold plate.

[0018] Furthermore, the cold source is liquid nitrogen or dry ice.

[0019] Furthermore, the ceramic slurry is a ceramic slurry used to prepare fuel cell electrodes, bioscaffolds, or microwave absorbing ceramics.

[0020] Furthermore, the conduit is made of porous insulation material, and / or the conduit has a double-layer sleeve structure with thermal insulation aerogel between the double sleeves, and / or the outer wall of the conduit is equipped with an electrically controlled temperature sleeve.

[0021] This invention achieves high-precision fabrication of horizontally ordered pores within porous ceramics using low cost and a simple structure, while avoiding the use of pore-forming agents, thus improving material performance and environmental friendliness. This invention enhances pore orientation and uniformity through a matrix of protrusions. The horizontal heat-conducting material of the thermally conductive mold and its array of protrusions forcefully guide ice crystal alignment, resulting in a pore parallelism deviation of <5%. It is suitable for gas diffusion layers in fuel cells requiring horizontal mass transfer. Furthermore, this invention relies solely on water crystallization for pore formation, leaving no impurities after sintering and improving the material's flexural strength. Moreover, the modular design of this invention supports parallel operation of multiple molds, with a single production cycle of ≤6 hours (compared to over 24 hours for traditional vacuum freezing methods), significantly improving the fabrication efficiency of porous ceramics. Attached Figure Description

[0022] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein:

[0023] Figure 1 is a structural schematic diagram of an embodiment of the present invention.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1. Insulated box; 2. First curved pipe wall; 3. Insulation film; 4. Conduit; 5. Cold plate; 6. Second curved pipe wall; 7. Array of protrusions; 8. Cold source. Detailed Implementation

[0026] To make the technical problem to be solved, the technical solution, and the beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this utility model and are not intended to limit this utility model.

[0027] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the present invention, and does not imply that every embodiment of the present invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0028] In one basic embodiment, the directional freezing device of this invention includes an insulated box 1, a heat-conducting mold, an array of protrusions 7, an insulation film 3, a conduit 4, and a cold source 8.

[0029] Insulation box 1 is used to insulate the entire directional refrigeration unit from the outside environment. The material of insulation box 1 can be common insulation materials, or you can purchase a suitable ready-made insulation box.

[0030] The heat-conducting mold is placed in an insulated box. This invention's heat-conducting mold is formed by splicing a first curved tube wall 2 and a second curved tube wall 6, ultimately creating a cylindrical structure with openings at both the top and bottom. The thermal conductivity of the first curved tube wall 2 is lower than that of the second curved tube wall 6. This difference in thermal conductivity between the two curved tube walls creates a horizontal temperature gradient in the ceramic. It is important to note that the boundary line between the first and second curved tube walls is parallel to the central axis of the heat-conducting mold.

[0031] The array of protrusions 7 is disposed on the inner side of the second curved tube wall 6. The array of protrusions 7 can be disposed on a portion of the inner side of the second curved tube wall 6, for example, only on the second curved tube wall 6 between the two layers of heat insulation film, or on the entire inner side of the second curved tube wall 6. The specific situation depends on actual needs such as ease of processing.

[0032] The heat insulation film 3 is used to seal the upper and lower parts of the heat-conducting mold. It's important to note that it's not used to seal the ends of the heat-conducting mold 3; the heat insulation film 3 can have a certain distance from the upper and lower end faces of the heat-conducting mold. Specifically, the upper heat-conducting film may or may not have a distance from the upper end face of the tubular heat-conducting mold. Ceramic slurry is poured into the heat-conducting mold between the upper and lower heat insulation films.

[0033] The conduit 4 has two ends, one end located outside the insulation box 1, and the other end located inside the heat-conducting mold between the upper and lower insulation films 3. The portion between the two ends of the conduit 4 passes through the lower circumferential wall of the heat-conducting mold and also through the insulation film located below the heat-conducting mold. The conduit 4 is used to fill the heat-conducting mold between the insulation films with ceramic slurry. The conduit can be made of porous insulation material to form an insulated conduit, or the conduit can be a double-layered sleeve structure with heat-insulating aerogel placed in the spacer between the double sleeves, thereby giving the conduit insulation function. In addition, an electrically controlled temperature jacket can be added to the outer wall of the conduit for active insulation. These three methods can be combined arbitrarily.

[0034] The cooling component is located at the bottom of the heat-conducting mold and exchanges heat with it. This invention improves the structure of the heat-conducting mold by using a first curved tube wall and a second curved tube wall with different thermal conductivity to form the heat-conducting module. This results in a temperature gradient in the horizontal direction of the heat-conducting mold, and the array of protrusions can form uniformly arranged pores. Therefore, the cooling component can be a relatively conventional and low-cost cooling component. The same principle applies to other components. This results in a simple, low-cost directional freezing device that can prepare functional ceramic materials with horizontally through-holes.

[0035] In a preferred embodiment, the cross-sections of the first curved tube wall 2 and the second curved tube wall 6 perpendicular to the axis of the heat-conducting mold are semi-circular, and the boundary between the first curved tube wall 2 and the second curved tube wall 6 is parallel to the central axis of the heat-conducting mold.

[0036] In this embodiment, the two parts of the heat-conducting mold with a temperature gradient are evenly distributed, thereby forming a temperature gradient in the horizontal direction as wide as possible in the diametrical direction. In other embodiments, the cross-sections of the first curved tube wall 2 and the second curved tube wall 6 perpendicular to the axis of the heat-conducting mold can also be arc-shaped, that is, the arc angle is greater than 180° or less than 180°. For example, the arc angle of the cross-section of the first curved tube wall can be 170°, and the corresponding arc angle of the cross-section of the second curved tube wall is 190°. The specific arc angles of the cross-sections can be adjusted by those skilled in the art according to the actual processing accuracy or processing needs, and are not limited to the data listed in this utility model.

[0037] In one specific embodiment, the first curved tube wall 2 is made of an organic material, such as porous PVC, PI, PMI, polytetrafluoroethylene, etc. The second curved tube wall 6 is made of copper, aluminum, or glass.

[0038] The first and second curved tube walls can be made from materials with better thermal conductivity selected from the above materials, ultimately forming a circular tube-shaped heat-conducting module.

[0039] In one embodiment, the spacing between adjacent bumps of the array bump 7 is 1-100 μm. Taking a specific bump as an example, the spacing between its front and rear bumps and the spacing between its left and right bumps can be the same or different, but the left and right spacing of all bumps is the same, and the front and rear spacing of all bumps is the same, thus forming a uniformly distributed array arrangement.

[0040] In a preferred embodiment, the array bumps 7 are cone-shaped, which can be either circular or square, thus facilitating the formation of uniform pores in the ceramic material.

[0041] The cooling assembly of this invention includes a cold plate 5 supported at the bottom of a heat-conducting mold and a cold source 8 that exchanges heat with the cold plate 5. This cooling assembly can utilize existing conventional cooling components without incurring additional costs for the directional refrigeration device. Specifically, the cold source can be liquid nitrogen or dry ice, both of which are relatively conventional cold sources.

[0042] The working process of the directional freezing device of this utility model is described below.

[0043] When preparing the corresponding ceramic material, the cold source 8 is first activated. After the temperature inside the insulation box 1 stabilizes, the ceramic slurry (such as SiC water-based slurry) is injected into the heat-conducting mold through the heat-insulating conduit 4, forming a horizontal radial temperature gradient. Ice crystals form at the array point protrusions 7. Driven by the gradient, the water in the slurry crystallizes along the horizontal array point direction, starting from each array protrusion. The ice crystal growth is guided by the temperature difference to form parallel channels.

[0044] After freezing, the heat-conducting mold is removed and freeze-dried. After the ice crystals of the ceramic material sublimate, horizontally ordered pores are left. Porous ceramics are obtained by sintering.

[0045] The ceramic slurry referred to in this invention can be a ceramic slurry for preparing fuel cell electrodes, biological scaffolds, or microwave absorbing ceramics. The ceramic materials required for fuel cell electrodes, biological scaffolds, microwave absorbing ceramics, etc., are all ceramic materials that require horizontally interconnected channels. Moreover, this invention does not require the addition of pore-forming agents to the ceramic materials, and will not leave impurities after sintering that would affect the purity of the ceramic materials.

[0046] In the description of this utility model, it should be understood that directional terms such as "front, back, up, down, left, right," "horizontal, vertical, horizontal," and "top, bottom," indicating directions or positional relationships, are generally based on the directions or positional relationships shown in the accompanying drawings. They are used only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this utility model. The directional terms "inner" and "outer" refer to the inner or outer contours relative to the outline of each component itself.

[0047] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0048] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A directional freezing device, characterized in that, include: Insulated box; A thermally conductive mold is set in a heat-insulating box. It is a circular tube structure spliced ​​together by a first curved tube wall and a second curved tube wall, and the thermal conductivity of the first curved tube wall is lower than that of the second curved tube wall. The array of protrusions is located on the inner side of the second curved tube wall; the heat insulation film is used to seal the upper and lower parts of the heat-conducting mold; the conduit has one end located outside the heat insulation box and the other end located inside the heat-conducting mold between the upper and lower heat insulation films for filling the heat-conducting mold with ceramic slurry, and the portion between the two ends of the conduit passes through the circumferential wall of the lower part of the heat-conducting mold and the heat insulation film located at the lower part. A cooling component is disposed at the bottom or top of the heat-conducting mold and exchanges heat with the heat-conducting mold.

2. The directional freezing device as described in claim 1, characterized in that, The cross-sections of the first and second curved tube walls perpendicular to the axis of the heat-conducting mold are semi-circular, and the boundary between the first and second curved tube walls is parallel to the central axis of the heat-conducting mold.

3. The directional freezing device as described in claim 1, characterized in that, The first curved tube wall is made of organic material, and the second curved tube wall is made of copper, aluminum or glass.

4. The directional freezing device as described in claim 1, characterized in that, The spacing between adjacent bumps in the array is 1-100 μm.

5. The directional freezing apparatus as described in claim 1, characterized in that, The bumps in the array are cone-shaped.

6. The directional freezing apparatus as described in claim 1, characterized in that, The cooling assembly includes a cold plate supported at the bottom of the heat-conducting mold and a cold source that exchanges heat with the cold plate.

7. The directional freezing apparatus as described in claim 6, characterized in that, The cold source is liquid nitrogen or dry ice.

8. The directional freezing apparatus as described in claim 1, characterized in that, The ceramic slurry is used to prepare fuel cell electrodes, bioscaffolds, or microwave absorbing ceramics.

9. The directional freezing apparatus as described in claim 1, characterized in that, The conduit is made of porous insulation material, and / or the conduit has a double-layer sleeve structure with thermal insulation aerogel between the double sleeves, and / or the outer wall of the conduit is provided with an electrically controlled temperature sleeve.

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