Cooling structure surface-treated with thermal conductive material and cooling method of cryogenic system by using same

Abstract

According to the present invention, a pattern layer, in which at least two materials having different thermal conductivities are alternately arranged to form a pattern, is provided on an inner surface of a fluid accommodation part; when a low-temperature liquid fluid or a cryogenic liquid fluid is injected into the fluid accommodation part for pre-cooling, the fluid is phase-changed into a gaseous state on a surface having high thermal conductivity among inner surfaces of the fluid accommodation part, and the fluid is induced to remain in a liquid state on a surface having relatively low thermal conductivity among the inner surfaces; and thus contact of liquid is induced on the surfaces during a pre-cooling process, so that the change from gas film boiling to transition boiling can be more quickly performed, and thus the cooling efficiency thereof can be further improved. In addition, Teflon having lower thermal conductivity than metal is coated on the inner surfaces of the fluid accommodation part formed of metal to form a pattern layer; and thus the structure thereof is simple, the manufacturing thereof is easy, and also the cooling efficiency thereof can be effectively improved.

Description

Cooling structure surface-treated with low thermal conductivity material and cooling method of cryogenic system utilizing the same

[0001] The present invention relates to a cooling structure surface-treated with a low thermal conductivity material and a cooling method for a cryogenic system utilizing the same, and more particularly, to a cooling structure surface-treated with a low thermal conductivity material, which can further improve cooling efficiency during pre-cooling of a fluid receiving portion by forming a patterned layer made of a low thermal conductivity material on a portion of the inner surface of the fluid receiving portion, and to a cooling method for a cryogenic system utilizing the same.

[0002] Recently, the use of cryogenic fluids has been increasing in various fields. Specifically, liquid oxygen is increasingly used as an oxidizer in the aerospace sector, and hydrogen energy is increasingly used as a new energy source in the energy sector. Considering volume reduction per mass, cryogenic fluids must be stored and transported in a liquid state, necessitating a cryogenic system.

[0003] A cryogenic system is a general term for a system that creates, maintains, and controls extremely low temperatures, and its interior is made of metal walls of sufficient strength to withstand extreme temperature changes and pressures. A cryogenic system requires a pre-cooling process during normal operation. This pre-cooling process involves injecting cryogenic fluid into a cryogenic fluid tank at room temperature and sufficiently cooling it to maintain the cryogenic fluid in a liquid state. During this pre-cooling process, the cryogenic fluid passes through the vapor film boiling region, transition boiling region, and nucleate boiling region. In other words, when a liquid cryogenic fluid is injected into a cryogenic fluid tank at room temperature, a phase change occurs instantly, covering the internal surface with a gas film. This is called the vapor film boiling region. In this vapor film boiling region, heat transfer efficiency is low because a gas with low thermal conductivity is in contact with the surface, preventing the metal surface from cooling quickly. When the temperature of the internal surface in the above-mentioned gas film boiling region is sufficiently low, it moves to the transition boiling region, where not only gas but also a liquid film coexist on the surface, resulting in a higher cooling efficiency. In the above-mentioned transition boiling region, direct contact occurs between a liquid with high heat transfer efficiency and the metal surface, cooling the surface and resulting in a heat transfer efficiency higher than that in the gas film boiling region. Afterwards, it moves to the nucleate boiling region.

[0004] Conventional cryogenic systems suffer from the problem of remaining in the gas film boiling region, where cooling efficiency is extremely low, for most of the initial cooling period. This leads to prolonged total cooling time and significantly reduced cooling efficiency. Therefore, a technology is needed to rapidly transition from the gas film boiling region in the initial cooling phase to the transition boiling region, thereby shortening cooling time.

[0005] The purpose of the present invention is to provide a cooling structure having a surface treated with a low thermal conductivity material that can further improve cooling efficiency during pre-cooling of a fluid receiving portion, and a cooling method of a cryogenic system utilizing the same.

[0006] A cooling structure surface-treated with a low thermal conductivity material according to the present invention comprises: a fluid receiving portion whose internal surface comes into contact with a liquid low-temperature or cryogenic fluid in which boiling heat transfer occurs; and a pattern layer formed in a pattern in which materials having different thermal conductivities are alternately arranged on at least a portion of the internal surface of the fluid receiving portion.

[0007] The pattern layer includes a first pattern layer formed by a first material having a first thermal conductivity, and the first material is arranged on the inner surface of the fluid receiving portion at a preset distance (d) to form a first pattern; and a second pattern layer formed by stacking a second material having a second thermal conductivity lower than the first thermal conductivity on the remaining portion of the inner surface excluding the first pattern, to form a second pattern arranged between the first patterns on the inner surface of the fluid receiving portion.

[0008] The above first pattern layer is formed integrally with the fluid receiving portion.

[0009] The above separation distance (d) is set to half of the distance (λ) between two points where bubbles are generated because the thickness of the gas film is formed thicker than the surroundings in Zuber's minimum film boiling model, which is defined by the mathematical formula below, and the distance (λ) between the two points is set to satisfy the mathematical formula below.

[0010] [Mathematical formula]

[0011]

[0012] Here, σ: surface tension of the cryogenic fluid, ρ: density of the cryogenic fluid, and g: acceleration of gravity.

[0013] The first material is a metal, and the second material uses a low-heat material having a thermal conductivity of 1 / 10 or less of the thermal conductivity of the first material.

[0014] The above pattern layer is formed by alternately and repeatedly arranging first and second materials having different thermal conductivities in a square shape to form a mosaic pattern.

[0015] The pattern layer is formed by stacking a second material having lower thermal conductivity than the first material on the surface of the first material at a preset distance, and forming a lattice pattern in a portion of the surface of the first material where the second material is not stacked, so that the first material and the second material are alternately exposed to the fluid.

[0016] The above pattern layer forms a concentric pattern in which first and second materials having different thermal conductivities are alternately arranged and have different diameters and are arranged in a concentric circle.

[0017] According to another aspect of the present invention, a cooling structure having a surface treated with a low thermal conductivity material comprises: a fluid receiving portion whose internal surface is in contact with a liquid low temperature or cryogenic fluid in which boiling heat transfer occurs; A pattern layer is provided on at least a portion of the inner surface of the fluid receiving portion, and is formed in a mosaic pattern in which materials having different thermal conductivities are alternately arranged on the inner surface, wherein the pattern layer comprises a first material, a second material having lower thermal conductivity than the first material, and is laminated on the surface of the first material at a preset separation distance (d), and the surface of the first material forms a grid pattern in a portion where the second material is not laminated, such that the first material and the second material are alternately exposed to the fluid, the first material is a metal, and the second material includes Teflon, and the separation distance (d) is set to half of the distance (λ) between two points where a gas film is formed thicker than the surroundings and bubbles are generated in Zuber's minimum film boiling model defined by the following mathematical equation, and the distance (λ) between the two points is set to satisfy the following mathematical equation.

[0018] [Mathematical formula]

[0019]

[0020] Here, σ: surface tension of the cryogenic fluid, ρ: density of the cryogenic fluid, and g: acceleration of gravity.

[0021] A cooling method of a cryogenic system utilizing a cooling structure surface-treated with a low thermal conductivity material according to the present invention comprises the steps of forming a pattern layer by arranging a material having a lower thermal conductivity than the solid surface in a spaced pattern on at least a portion of a solid surface of a cooling target; and the step of bringing a liquid low-temperature or cryogenic fluid into contact with the cooling target, the fluid in contact with the solid surface vaporizes to cover the solid surface with a gas film, and the fluid is continuously supplied in a liquid state to the pattern layer to achieve continuous phase-change heat transfer, thereby cooling.

[0022] A cooling structure surface-treated with a low thermal conductivity material according to another aspect of the present invention comprises: a cooling object formed of metal; and a pattern layer formed by arranging a material having a lower thermal conductivity than the cooling object in a spaced pattern on at least a portion of the surface of the cooling object.

[0023] According to another aspect of the present invention, a cooling structure surface-treated with a low thermal conductivity material comprises: a cooling object having a solid surface in contact with a liquid low-temperature or cryogenic fluid; and a patterned layer formed of a material having a lower thermal conductivity than the solid surface, the patterned layer being arranged in a pattern spaced apart from each other on the solid surface and in contact with the fluid, wherein the fluid vaporizes through heat transfer with the cooling object to cool the cooling object, wherein the fluid in contact with the solid surface vaporizes to cover the solid surface with a gas film, and the fluid is continuously supplied in a liquid state to the patterned layer to achieve continuous phase-change heat transfer, thereby cooling the cooling object.

[0024] The present invention provides a pattern layer in which at least two materials having different thermal conductivities are alternately arranged to form a pattern on the inner surface of a fluid receiving portion, so that when a liquid low-temperature or cryogenic fluid is injected into the fluid receiving portion for pre-cooling, the fluid changes into a gaseous state on a surface of the inner surface of the fluid receiving portion having high thermal conductivity, and the fluid remains in a liquid state on a surface of the inner surface having relatively low thermal conductivity, thereby inducing contact of the liquid on the surface during the pre-cooling process, thereby enabling a faster transition from gas film boiling to transition boiling, and thus improving cooling efficiency.

[0025] In addition, by forming a pattern layer by coating Teflon, which has lower thermal conductivity than the metal, on the inner surface of the fluid receiving portion formed of metal, the cooling efficiency can be effectively improved while the structure is simple and manufacturing is easy.

[0026] FIG. 1 is a cross-sectional view schematically illustrating a cryogenic system utilizing a cooling structure surface-treated with a low thermal conductivity material according to one embodiment of the present invention.

[0027] Figure 2 is a plan view showing a pattern layer according to one embodiment of the present invention.

[0028] Figure 3 is a cross-sectional view taken along line AA of Figure 2.

[0029] Figure 4 is a schematic diagram of Zuber's minimum film boiling (MFB) model.

[0030] Figure 5 is a plan view showing a pattern layer according to another embodiment of the present invention.

[0031] Figure 6 is a cross-sectional view taken along the BB line of Figure 5.

[0032] Figure 7 is a graph comparing the improved cooling efficiency of a cryogenic system utilizing a cooling structure surface-treated with a low thermal conductivity material according to the present invention.

[0033] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings.

[0034] FIG. 1 is a cross-sectional view schematically illustrating a cryogenic system utilizing a cooling structure surface-treated with a low thermal conductivity material according to one embodiment of the present invention.

[0035] Referring to FIG. 1, a cryogenic system according to one embodiment of the present invention is a system in which a cooling structure utilizing boiling is applied.

[0036] The above cryogenic system includes a cooling target having a solid surface in contact with a liquid low-temperature or cryogenic fluid (hereinafter referred to as a cryogenic fluid) in which boiling heat transfer occurs, and a pattern layer (20) formed of a material having lower thermal conductivity than the solid surface and arranged in a pattern spaced apart from each other on the solid surface of the cooling target so as to be in contact with the fluid.

[0037] The above cooling object is explained as an example of a fluid receiving unit that receives cryogenic fluid, and the fluid receiving unit is explained as an example of a cryogenic fluid tank (LN2pool) (10).

[0038] However, the fluid receiving portion is not limited thereto, and can be applied in various ways as long as it comes into contact with cryogenic fluid, such as a transport pipe transporting cryogenic fluid.

[0039] The above cryogenic fluids include liquid nitrogen (LN2), liquid oxygen (LO2), liquid hydrogen (LH2), liquefied natural gas (LNG), etc.

[0040] The above cryogenic fluid tank (10) includes a chamber (11) for accommodating cryogenic fluid and an insulating material (12) surrounding the outside of the chamber (11).

[0041] The above chamber (11) is a container made of metal. In this embodiment, the metal is described as stainless steel (SUS) by way of example.

[0042] Fig. 2 is a plan view showing a pattern layer according to one embodiment of the present invention. Fig. 3 is a cross-sectional view taken along line AA of Fig. 2.

[0043] Referring to FIGS. 2 and 3, the pattern layer (20) is provided on at least a portion of the inner surface of the chamber (11).

[0044] In this embodiment, the pattern layer (20) is described as being provided on the bottom surface of the inner surface of the chamber (11), but is not limited thereto and may also be provided on the inner side surface.

[0045] The above pattern layer (20) is formed in a pattern in which materials having different thermal conductivities are alternately arranged on the inner bottom surface of the chamber (11). In this embodiment, an example is provided in which two first and second materials are alternately arranged in a pattern to have a heterogeneous surface.

[0046] The above pattern layer (20) includes a first pattern layer (21) and a second pattern layer (22).

[0047] The above first pattern layer (21) is formed by a first material having a first thermal conductivity. The first material is a metal, and is described as stainless steel as an example.

[0048] In this embodiment, since the chamber (11) is formed of the same metal as the first material, the first pattern layer (21) is formed integrally with the chamber (11) to form the inner surface of the chamber (11), but is not covered by the second pattern layer (22) and is exposed to the surface to form the first pattern described later. However, the present invention is not limited thereto, and the first pattern layer (21) may of course be formed separately on the inner surface of the chamber (11) if it is made of a different material from the chamber (11).

[0049] The first pattern layer (21) is formed so that the first material is exposed at a preset distance (d) on the inner bottom surface of the chamber (11) to form a first pattern.

[0050] The above first pattern is explained as an example in which the first material is exposed in a square shape at a distance (d) apart from each other to form a mosaic pattern.

[0051] The above second pattern layer (22) is formed by a second material having a second thermal conductivity. The second thermal conductivity must be lower than the first thermal conductivity.

[0052] The thermal conductivity of the second material is explained by way of example using a low thermal conductivity material having a thermal conductivity of approximately 1 / 10 or less of the thermal conductivity of the first material. However, this is not limited to this, and if the thermal conductivity of the first material and the second material have a predetermined difference, the cooling efficiency can be improved.

[0053] In this embodiment, the second material is described as using Teflon as an example, but is not limited thereto, and can be applied in various ways as long as it is a low thermal conductivity material with lower thermal conductivity than the first material.

[0054] The thermal conductivity of stainless steel used as the first material is about 8 to 15 W / m·K at a temperature range of about 77 to 300 K, and the thermal conductivity of Teflon used as the second material is about 0.3 W / m·K or less.

[0055] The second pattern layer (22) is formed by being laminated on the first pattern layer (21). The second pattern layer (22) is a Teflon film layer formed by coating the second material with the second pattern on the remaining portion of the inner surface of the chamber (11) excluding the first pattern. Accordingly, the second pattern is arranged between the first patterns.

[0056] In this embodiment, since the chamber (11) and the first pattern layer (21) are made of the same metal and are integrally formed, the second pattern layer (22) is a Teflon film layer formed by applying the second material on the surface of the chamber (11) so as to form the second pattern. That is, the first pattern layer (21) is an exposed portion of the inner surface of the chamber (11), and the second pattern layer (21) is a separate layer laminated on a portion other than the first pattern layer (21) on the inner surface of the chamber (11).

[0057] However, it is not limited to this, and when the first pattern layer (21) is formed separately in a laminated manner on the surface of the chamber (11), it is also possible for the first pattern layer (21) and the second pattern layer (22) to be formed so as to be positioned on the same plane.

[0058] The above second pattern is explained as an example of a mosaic pattern in which the second materials are spaced apart from each other in a square shape.

[0059] Accordingly, the pattern layer (20) is formed as a mosaic pattern in which first and second materials having different thermal conductivities are alternately and repeatedly arranged in a square shape, as shown in FIG. 2.

[0060] The distance between surfaces with high thermal conductivity in the above pattern layer (20), i.e., the separation distance (d) between adjacent first materials in the first pattern layer (21), is set through Zuber's minimum film boiling (MFB) model defined by the following mathematical equation.

[0061] Figure 4 is a schematic diagram of Zuber's minimum film boiling (MFB) model.

[0062] Referring to Figure 4, in Zuber's minimum film boiling model, it can be seen that the vapor film formed on the surface when the cryogenic fluid undergoes a phase change is generated in the form of a curve with a predetermined period (λ).

[0063] It can be seen that vapor bubbles are generated at the first and second points (P1) and (P2) where the thickness of the gas film is the thickest, and that there is a part where the thickness of the gas film is relatively very thin between the first point (P1) and the second point (P2).

[0064] Mathematical expression 1 represents the distance (λ) between the thickest parts of the gas film, i.e., the distance between the first point (P1) and the second point (P2) where bubbles are generated.

[0065]

[0066] Here, σ: surface tension of the cryogenic fluid, ρ: density of the cryogenic fluid, and g: acceleration of gravity.

[0067] In the present invention, the pattern layer (20) was formed with reference to the Zuber's minimum film boiling model and mathematical formula as described above.

[0068] Referring to FIG. 4 and mathematical expression 1, the thickness of the gas film is relatively thicker than the surrounding area, so the first material is placed in an area where bubbles are generated, thereby forming a surface with high thermal conductivity, thereby causing bubbles to be generated in the first pattern layer (21).

[0069] In addition, by arranging the second material in an area where the thickness of the gas film is relatively thinner than the surrounding area, a surface with low thermal conductivity can be formed, thereby inducing a liquid-state cryogenic fluid to remain in the second pattern layer (22).

[0070] Accordingly, the separation distance (d) between the first materials adjacent to each other in the first pattern layer (21) was set to half of the distance (λ) between the parts where the thickness of the gas film is thicker than the surroundings from Zuber's minimum film boiling model.

[0071] That is, the distance (d) between the first materials of the first pattern layer (21) having high thermal conductivity in the pattern layer (20) is set to half of the distance (λ) between the points where the bubbles are generated in the mathematical formula, and the second materials are patterned and applied between the first materials to form the second pattern.

[0072] Therefore, the distance (d) between the adjacent first materials in the first pattern layer (21) is the same as the size of the second materials in the second pattern layer (22).

[0073] By using the minimum film boiling model of Zuber, the distance (d) between the first materials in the first pattern layer (21) is calculated, and the position and size of the second materials in the second pattern layer (22) are set, so that when the phase of the cryogenic fluid changes, the liquid state of the cryogenic fluid remains on the second material, which has lower thermal conductivity than the surroundings, thereby allowing the liquid state of the cryogenic fluid, which has higher heat transfer efficiency than the gas, to contact the surface and cool the surface of the cryogenic fluid tank (10) more quickly.

[0074] In this embodiment, the spacing distance (d) between the first materials of the first pattern layer (21) is set to half of the spacing (λ) between the points where the bubbles are generated in the mathematical formula, as an example.

[0075] However, it is not limited thereto, and the above-mentioned separation distance (d) can be varied within a range of error of half of the above-mentioned spacing (λ), but the highest cooling efficiency can be achieved when arranged to be spaced apart by the above-mentioned separation distance (d).

[0076] Additionally, it is possible for the second material to be laminated over the entire surface of the first material, and the cooling efficiency can be improved compared to when the second material is not present.

[0077] Figure 7 is a graph comparing the cooling efficiency in the case of a conventional single metal surface (bare metal surface) and in the case of a double surface (multi-level surface) including a pattern layer according to the present invention.

[0078] Referring to Fig. 7, in the case of the double surface of the present invention, it can be seen that the heat flux according to the wall superheat is higher than in the conventional case.

[0079] A cooling method of a cryogenic system utilizing a cooling structure surface-treated with a low thermal conductivity material according to one embodiment of the present invention configured as described above is described as follows.

[0080] The pre-cooling process of the above cryogenic fluid tank (10) is a process for cooling the interior of the cryogenic fluid tank (10) by injecting a liquid-state cryogenic fluid into the cryogenic fluid tank (10) at room temperature. The above pre-cooling process includes a gas film boiling region, a transition boiling region, and a nucleate boiling region depending on the phase change process of the cryogenic fluid.

[0081] In the present invention, since the inner surface of the cryogenic fluid tank (10) is formed by alternately arranging first and second materials having different thermal conductivities to form the first and second patterns, when the cryogenic fluid is injected, the heat transfer rate differs depending on which position of the first and second patterns the cryogenic fluid comes into contact with on the inner surface of the cryogenic fluid tank (10).

[0082] When the cryogenic fluid is injected into the cryogenic fluid tank (10), boiling heat transfer occurs. At least a portion of the cryogenic fluid comes into contact with the first pattern layer (21), and the remainder comes into contact with the second pattern layer (22).

[0083] The fluid in contact with the first pattern layer (21) undergoes a rapid phase change and vaporizes, cooling the surface while vaporizing through heat transfer with the first pattern layer (21). Since the first pattern layer (21) among the internal surfaces of the cryogenic fluid tank (10) has a relatively high thermal conductivity compared to other parts, the surface of the first pattern layer (21) is covered with a gas film, thereby lowering the cooling efficiency.

[0084] The fluid in contact with the second pattern layer (22) cools the surface by heat transfer with the second pattern layer (22). Since the second pattern layer (22) is a region of the inner surface of the cryogenic fluid tank (10) that has a relatively lower thermal conductivity than the first pattern layer (21), the fluid in contact with the surface of the second pattern layer (22) is induced to remain in a liquid state. Therefore, continuous phase change heat transfer is possible on the surface of the second pattern layer (22), resulting in high cooling efficiency.

[0085] Since the second pattern layer (22) is formed by applying Teflon, which has a much lower thermal conductivity than metal, it is possible to prevent the second pattern layer (22) from being 100% covered by a gas film.

[0086] As described above, the cryogenic fluid in contact with the surface of the first pattern layer (21) vaporizes by boiling heat transfer on the surface of the first pattern layer (21), thereby forming a vapor film on the surface of the first pattern layer (21).

[0087] Meanwhile, on the surface of the second pattern layer (22), the gaseous fluid formed by vaporization of the cryogenic fluid is induced to remain in a liquid state without forming a gas film covering the entire area.

[0088] That is, the area covered with gas on the surface of the first pattern layer (21) is larger than the area covered with gas on the surface of the second pattern layer (22).

[0089] As described above, when a liquid low-temperature or cryogenic fluid is brought into contact with the surface of the cryogenic fluid tank (10), boiling heat transfer occurs. The fluid coming into contact with the surface of the first pattern layer (21) is covered with a gas film due to rapid phase change heat transfer, thereby reducing cooling efficiency, whereas the fluid coming into contact with the surface of the second pattern layer (22) can remain partially in a liquid state, thereby enabling continuous phase change heat transfer. That is, since a liquid-state cryogenic fluid having a higher heat transfer efficiency than a gas-state is continuously supplied to the surface of the second pattern layer (22), continuous phase change heat transfer is achieved, thereby allowing the surface of the cryogenic fluid tank (10) to be cooled more quickly.

[0090] Therefore, in the gas film boiling region, which is the initial stage of the pre-cooling process of the cryogenic fluid, not only a gas film but also a liquid film coexist on the inner surface of the cryogenic fluid tank (10), so that the transition boiling region can be more quickly transitioned from the gas film boiling region. Since the transition boiling region has a cooling efficiency much higher than the gas film boiling region, the inner surface can be cooled more rapidly. Since the time required for the gas film boiling region is drastically shortened and the transition to the transition boiling region can be quickly performed, the cooling efficiency of the pre-cooling process can be greatly improved.

[0091] Meanwhile, Fig. 5 is a plan view showing a pattern layer according to another embodiment of the present invention. Fig. 6 is a cross-sectional view taken along line BB of Fig. 5.

[0092] According to another embodiment of the present invention, a cryogenic system surface-treated with a low thermal conductivity material is provided, wherein a pattern layer (30) formed on the inner surface of a chamber (11) of the cryogenic fluid tank (10) is formed such that, among first and second materials having different thermal conductivities, the first material having a higher thermal conductivity than the second material is formed such that a grid pattern in which horizontal and vertical patterns intersect is exposed on the surface, and the second material is different from the first embodiment in that it is arranged between the grid patterns, and the remaining configuration and operation are similar to the above embodiment, so that a detailed description of similar contents will be omitted below and a description will be given focusing on the differences.

[0093] The above chamber (11) is formed of the first material.

[0094] The above pattern layer (30) includes a first pattern layer (31) formed of the first material, and a second pattern layer (32) in which the second material is arranged at a preset distance on the surface of the first material.

[0095] In this embodiment, the first pattern layer (31) is formed integrally with the chamber (11) to form the inner surface of the chamber (11), but is not covered by the second pattern layer (32) and is exposed to the surface to form a pattern. However, the present invention is not limited thereto, and the first pattern layer (31) may of course be formed separately on the inner surface of the chamber (11) if it is made of a different material from the chamber (11).

[0096] That is, the first pattern layer (31) is a layer exposed to the fluid, in which a portion of the surface of the first material on which the second material is not laminated forms a grid pattern in which horizontal and vertical patterns intersect.

[0097] The second pattern layer (32) forms a pattern in which the second material is alternately and repeatedly arranged in a square shape between the grid patterns, and is exposed to the fluid.

[0098] Accordingly, the inner surface of the chamber (11) is alternately arranged with the first material and the second material, so that the first material and the second material are alternately exposed to the fluid.

[0099] In this embodiment, an example is given in which the second material is formed by coating at least a portion of the surface of the first material, so that at least a portion of the surface of the first material is covered by the second material, and the remaining portion is exposed in a grid pattern between the second pattern layers (32) having a square shape.

[0100] The distance (d) between the first material and the second material in the pattern layer (30) and exposed without being covered by the second material is set by the mathematical expression 1.

[0101] The above first material uses a metal with high thermal conductivity, and in this embodiment, stainless steel is used as an example.

[0102] The second material is Teflon, for example. The second material is coated with the grid pattern on the first material.

[0103] Meanwhile, the pattern layer (30) is not limited to the above embodiments, and can be applied by changing to a pattern other than the grid pattern. That is, the pattern layer can be applied by changing to various patterns as long as the first material and the second material are alternately arranged so that the inner surface of the chamber (11) can have a surface with different thermal conductivities. For example, the pattern layer (30) can also form a concentric pattern in which the first material and the second material are alternately arranged so that they have different diameters and are arranged in concentric circles.

[0104] While the present invention has been described with reference to the embodiments illustrated in the drawings, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the appended claims.

[0105] According to the present invention, a cooling structure surface-treated with a low thermal conductivity material capable of further improving cooling efficiency during pre-cooling of a fluid receiving portion and a cryogenic system utilizing the same can be manufactured.

Claims

1. A fluid receiving portion whose internal surface comes into contact with a low-temperature or cryogenic liquid fluid in which boiling heat transfer occurs; A pattern layer formed in a pattern in which materials having different thermal conductivities are alternately arranged on at least a portion of the inner surface of the fluid receiving portion, Cooling structure surface-treated with low thermal conductivity material.

2. In claim 1, The above pattern layer is, A first pattern layer formed by a first material having a first thermal conductivity, and wherein the first material is arranged on the inner surface of the fluid receiving portion to be spaced apart by a preset distance (d) to form a first pattern; A second pattern layer is formed by laminating a second material having a second thermal conductivity lower than the first thermal conductivity on the remaining portion of the inner surface excluding the first pattern, thereby forming a second pattern disposed between the first patterns on the inner surface of the fluid receiving portion. Cooling structure surface-treated with low thermal conductivity material.

3. In claim 2, The above first pattern layer is formed integrally with the fluid receiving portion and forms the inner surface of the fluid receiving portion. Cooling structure surface-treated with low thermal conductivity material.

4. In claim 2, The above separation distance (d) is set to half of the distance (λ) between two points where bubbles are generated because the thickness of the gas film is formed thicker than the surroundings in Zuber's minimum film boiling model, which is defined by the mathematical formula below. The distance (λ) between the two points above is, It is set to satisfy the following mathematical formula: Cooling structure surface-treated with low thermal conductivity material. [Mathematical formula] Here, σ: surface tension of the cryogenic fluid, ρ: density of the cryogenic fluid, and g: gravitational acceleration.

5. In claim 2, The above first material is metal, The thermal conductivity of the second material is 1 / 10 or less of the thermal conductivity of the first material, and uses a low-heat material. Cooling structure surface-treated with low thermal conductivity material.

6. In claim 1, The above pattern layer is, The first and second materials having different thermal conductivities are alternately and repeatedly arranged in a square shape to form a mosaic pattern. Cooling structure surface-treated with low thermal conductivity material.

7. In claim 1, The above pattern layer is, A second material having lower thermal conductivity than the first material is laminated on the surface of the first material at a preset distance, The surface of the first material above forms a grid pattern in the area where the second material is not laminated. The first material and the second material are formed so that they are alternately exposed to the fluid. Cooling structure surface-treated with low thermal conductivity material.

8. In claim 1, The above pattern layer is, The first and second materials having different thermal conductivities are arranged alternately and formed in a concentric pattern with different diameters and concentrically arranged. Cooling structure surface-treated with low thermal conductivity material.

9. A fluid receiving portion whose internal surface comes into contact with a low-temperature or cryogenic liquid fluid in which boiling heat transfer occurs; It comprises a pattern layer provided on at least a portion of the inner surface of the fluid receiving portion, and in which materials having different thermal conductivities are alternately arranged on the inner surface, The above pattern layer is, A second material having lower thermal conductivity than the first material is laminated on the surface of the first material at a preset distance (d), The surface of the first material above forms a grid pattern in the area where the second material is not laminated. The first material and the second material are formed so as to be alternately exposed to the fluid, The first material is a metal, and the second material includes Teflon. The above separation distance (d) is set to half of the distance (λ) between two points where bubbles are generated because the thickness of the gas film is formed thicker than the surroundings in Zuber's minimum film boiling model, which is defined by the mathematical formula below. The distance (λ) between the two points above is, It is set to satisfy the following mathematical formula: Cooling structure surface-treated with low thermal conductivity material. [Mathematical formula] Here, σ: surface tension of the cryogenic fluid, ρ: density of the cryogenic fluid, and g: gravitational acceleration.

10. A step of forming a pattern layer by arranging a material having a lower thermal conductivity than the solid surface in a spaced pattern on at least a portion of a solid surface of a cooling target; A step of cooling the solid surface by contacting the solid surface with a liquid low-temperature or cryogenic fluid, the fluid contacting the solid surface vaporizes and covers the solid surface with a gas film, and the fluid is continuously supplied to the pattern layer in a liquid state to achieve continuous phase-change heat transfer, comprising: A cooling method for a cryogenic system utilizing a cooling structure surface-treated with a low thermal conductivity material.

11. A cooling target formed of metal; A pattern layer formed by arranging a material having a lower thermal conductivity than the cooling object in a spaced pattern on at least a portion of the surface of the cooling object, Cooling structure surface-treated with low thermal conductivity material.

12. In a cooling structure surface-treated with a low thermal conductivity material, A cooling object having a solid surface in contact with a liquid low-temperature or cryogenic fluid; and A pattern layer is formed of a material having lower thermal conductivity than the solid surface and is arranged in a spaced pattern on the solid surface and in contact with the fluid. The fluid is vaporized by heat transfer with the cooling target object to cool the cooling target object, and the fluid in contact with the solid surface vaporizes to cover the solid surface with a gas film, and the fluid is continuously supplied to the pattern layer in a liquid state to enable continuous phase change heat transfer, thereby cooling the solid surface. Cooling structure surface-treated with low thermal conductivity material.

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