Micro-bulge multi-layer ultralow-temperature composite heat insulation structure

Abstract

The invention discloses a micro-bulge multi-layer ultralow-temperature composite heat insulation structure. An existing structure is formed by alternately stacking metal coating films and spacing materials and is poor in thermal deformation and stability in a wide temperature zone. The device comprises a low-temperature side heat insulation layer structure close to a cold end and a high-temperature side heat insulation layer structure close to a hot end, and vacuum packaging is adopted. The low-temperature side heat insulation layer structure comprises 10-20 spacer layers, the high-temperature side heat insulation layer structure comprises 20-30 spacer layers, and each spacer layer comprises a base layer and a reflecting layer attached to the base layer. A micro-bulge structure layer is arranged between every two adjacent spacing layers, and micro-bulges of the low-temperature side heat insulation layer structure are closed-cell polyurethane foam blocks with the density of 30-50kg / m; and the micro-bulge material of the high-temperature side heat insulation layer structure is zirconium tungstate or a zirconium tungstate composite material. High and negative thermal expansion coefficient material micro bulges are respectively arranged in a low-temperature area and a high-temperature area, so that the wide-temperature-area adaptability is high. The method is suitable for the fields of spacecrafts, liquid hydrogen storage tanks, vacuum heat insulation pipes and the like.

Description

Technical Field

[0001] This invention belongs to the field of materials technology, especially the field of thermal insulation materials, and specifically relates to a micro-protrusion multilayer ultra-low temperature composite thermal insulation structure. Background Technology

[0002] Currently, multilayer thermal insulation materials typically consist of several layers of metal-coated thin films and spacers stacked alternately to reduce total heat leakage. However, in practical applications, inconsistent thermal expansion of the materials during temperature changes can easily lead to deformation of the interlayer structure and increased contact area, resulting in decreased insulation performance and even problems such as material compaction and thermal bridging. Existing technologies have attempted to reduce the interlayer contact area by optimizing the spacer structure. Patent No. 85106550 discloses a multilayer thermal insulation system in which a high-reflectivity metal is coated on one side of a polyester film as a radiation shield, and the other side is coated with a low-thermal-conductivity silicate granular material as a spacer layer. This design effectively reduces the interlayer contact area through the granular spacer layer, thereby improving thermal insulation performance. Although the above solutions reduce the thermal contact area to some extent, the interlayer distance is uncontrollable or fluctuates significantly with temperature changes, and the material itself lacks temperature adaptability, making it difficult to cope with thermal deformation and stability requirements over a wide temperature range. Therefore, there is an urgent need for a multilayer insulation structure that has the ability to self-regulate thermal deformation, and can take into account low thermal conductivity, small interlayer contact area and high stability, so as to improve its long-term stability and insulation efficiency under large temperature difference environment. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of material thermal expansion mismatch, poor structural stability and difficulty in controlling contact area in existing multilayer insulation structures in a wide temperature range (such as 77K to 1000K), and to provide a micro-protruding multilayer ultra-low temperature composite insulation structure that has both excellent insulation performance and thermal stability.

[0004] The composite insulation structure of this invention includes a low-temperature side insulation layer structure near the cold end and a high-temperature side insulation layer structure near the hot end. The overall insulation structure is vacuum-sealed. The low-temperature side insulation layer structure encloses a tank containing a cryogenic liquid working fluid, and the high-temperature side insulation layer structure encloses the low-temperature side insulation layer structure. Both the low-temperature side insulation layer structure and the high-temperature side insulation layer structure are layered structures. The low-temperature side insulation layer structure includes 10 to 20 spacer layers, and the high-temperature side insulation layer structure includes 20 to 30 spacer layers. Each spacer layer includes a base layer and a reflective layer attached to the base layer, with the reflective layer located on the side of the spacer layer facing the hot end.

[0005] A micro-protrusion structure layer is provided between adjacent spacer layers. The micro-protrusion structure layer is composed of multiple micro-protrusions. Among them, the multiple micro-protrusions of the micro-protrusion structure layer closest to the cold end are arranged in a lattice. The micro-protrusions of the other micro-protrusion structure layers correspond to the radial projection positions of the innermost micro-protrusion.

[0006] The micro-protrusions of the low-temperature side insulation layer are closed-cell polyurethane foam blocks with a density of 30-50 kg / m³; the micro-protrusions of the high-temperature side insulation layer are made of zirconium tungstate ZrW2O8 or zirconium tungstate composite material.

[0007] Furthermore, the base layer is a polyester film or fiberglass paper, and the reflective layer is an aluminum foil or copper foil.

[0008] Furthermore, the micro-protrusions are all cuboids whose orthographic projection is a square, with a side length of 0.5 to 1.5 mm and a height of 0.5 to 1.5 mm. The distance between two adjacent innermost micro-protrusions is 2.0 to 3.0 mm.

[0009] Furthermore, the closed-cell polyurethane foam block has a thermal conductivity of 0.018–0.022 W / (m·K) and a coefficient of thermal expansion of 200 × 10⁻⁶. -6 ~500×10 -6 / K.

[0010] Furthermore, the coefficient of thermal expansion of the zirconium tungstate material is -9.1 × 10⁻⁶ K in the range of 300–923 K. -6 ~-7×10 -6 / K; The zirconium tungstate composite material is zirconium tungstate filled with ceramic material, with a filling amount of 40-60% of the total mass of the composite material, and a coefficient of thermal expansion of -1.2×10⁻⁶ K at 300-923 K. -6 ~1×10 -6 / K.

[0011] Furthermore, the ceramic material is alumina ceramic, with a coefficient of thermal expansion of 6.0 × 10⁻⁶ K at 300–923 K. -6 ~7.8×10 -6 / K.

[0012] The advantages and beneficial effects of this invention include: 1. This invention constructs an adaptive interval system with "segmented response" along the temperature range by arranging micro-protrusions of high thermal expansion coefficient material (such as polyurethane foam) in the low temperature range and micro-protrusions of negative thermal expansion material (zirconium tungstate) in the high temperature range. It has strong wide temperature range adaptability and can be applied to a variety of complex thermal environments from cryogenic to high temperature.

[0013] 2. This invention replaces "surface contact" with "point contact" using micro-protrusions, which significantly reduces the actual thermal contact area between layers, achieves self-adjustment of interlayer contact area, avoids compaction and failure, and improves insulation efficiency.

[0014] 3. The structure of this invention has high versatility and is applicable to various fields such as spacecraft, liquid hydrogen storage tanks, and vacuum insulation tubes. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the multi-layer thermal insulation structure of the present invention; Figure 2 This is a schematic diagram illustrating the variation of radiative heat transfer and solid thermal conductivity with the number of layers in this invention; Figure 3 This is a schematic diagram of the linear shrinkage rate of the material of the present invention; Figure 4 This is a schematic diagram of the overall heat leakage distribution in a specific implementation case. Detailed Implementation

[0016] like Figure 1 As shown, a micro-protruding multilayer cryogenic composite insulation structure includes a low-temperature side insulation layer structure I near the cold end and a high-temperature side insulation layer structure II near the hot end. The entire insulation structure is vacuum-sealed. In use, the cold end temperature is 20K or below, and the hot end temperature is 300K or above, reaching close to 1000K. The low-temperature side insulation layer structure I encloses a tank III containing a cryogenic liquid working fluid, and the high-temperature side insulation layer structure II encloses the low-temperature side insulation layer structure I.

[0017] Both the low-temperature side insulation layer structure I and the high-temperature side insulation layer structure II are layered structures. Low-temperature side insulation layer structure I includes 10-20 spacer layers, and high-temperature side insulation layer structure II includes 20-30 spacer layers. Each spacer layer includes a base layer 1 and a reflective layer 2 attached to the base layer, with the reflective layer 2 located on the side of the spacer layer facing the hot end. The base layer is made of polyester film or fiberglass paper, and the reflective layer is made of aluminum foil or copper foil. The spacer layers in both low-temperature side insulation layer structure I and high-temperature side insulation layer structure II can use the same material, or different materials.

[0018] Figure 2 This study illustrates the distribution of heat leakage under two different conditions in multilayer insulation structures with varying numbers of layers. In the 0-6 layer range (near the lowest temperature side), solid-state thermal conductivity is the primary factor causing heat leakage, and the proportion of solid-state thermal conductivity increases with the number of layers. The heat flux density of solid-state thermal conductivity in the first layer is 0.59 W / m². 2 The radiative heat transfer rate is 0.03 W / m². 2 At the sixth layer, the two heat leakage methods account for the same proportion of the total heat leakage. After the sixth layer, the thermal conductivity of the solid gradually decreases, gradually approaching a heat flux density of 0.6 W / m. 2 The proportion of radiative heat loss in the total heat loss gradually increases, reaching a heat flux density of 0.51 W / m² on the thirtieth floor. 2 . Figure 2 This demonstrates that using low-temperature side insulation layer structure I on the low-temperature side can effectively reduce solid thermal conductivity, while using high-temperature side insulation layer structure II on the high-temperature side maintains its stability, proving the reliability of the structure.

[0019] Low-temperature side micro-protrusion structures are provided between adjacent spacer layers of the low-temperature side insulation layer I, and on the outermost spacer layer. These low-temperature side micro-protrusion structures consist of a matrix arrangement of low-temperature side micro-protrusions 3. The innermost low-temperature side micro-protrusions 3 are arranged in a dot matrix pattern, while the low-temperature side micro-protrusions in the other layers correspond to the projected positions of the innermost micro-protrusion. Each low-temperature side micro-protrusion is a cuboid with a square projection, the side length of which is 0.5–1.5 mm, and the height of which is 0.5–1.5 mm. The axial spacing between two adjacent low-temperature side micro-protrusions is 2.0–3.0 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 30–50 kg / m³, a thermal conductivity of 0.018–0.022 W / (m·K), and a coefficient of thermal expansion of 200 × 10⁻⁶. -6 ~500×10 -6 / K. Within a temperature range of 77K to 300K, a volume expansion rate of 5% to 10% can be achieved, effectively supporting the layer and layer structure and avoiding compaction and bonding.

[0020] A high-temperature side micro-protrusion structure layer is provided between adjacent spacer layers of the high-temperature side insulation layer II. This layer consists of a lattice arrangement of high-temperature side micro-protrusions 4. The projection positions of the high-temperature side micro-protrusions 4 correspond to the innermost low-temperature side micro-protrusions, and the projections of the corresponding low-temperature side micro-protrusions in each layer overlap. Each high-temperature side micro-protrusion is a cuboid with a square orthographic projection, the side length of the square being 0.5–1.5 mm, and the side length of the cuboid being 0.5–1.5 mm. The axial distance between two adjacent high-temperature side micro-protrusions is 2.0–3.0 mm. The high-temperature side micro-protrusion material is zirconium tungstate (ZrW₂O₈) or a zirconium tungstate composite material. The zirconium tungstate composite material is zirconium tungstate with added filler material, such as ceramic material or expanded perlite, with an addition amount of 40–60% of the total mass of the composite material. The coefficient of thermal expansion of the high-temperature side micro-protrusions is -9.1 × 10⁻⁶ K from 300 K to 923 K. -6 ~-7×10 -6 / K can suppress high-temperature deformation. It is placed near the high-temperature end (such as the side of the spacecraft shell or the hot end interface). Its volume expansion remains almost unchanged in the temperature range of 300K to 923K. Its shape is stable in the high-temperature region, ensuring the stability of the interlayer gap.

[0021] Figure 3 The linear shrinkage rates of polyurethane foam and zirconium tungstate (ZrW2O8) at different temperatures were described. The linear shrinkage of polyurethane foam was 110% in the range of 77K to 300K, while that of zirconium tungstate (ZrW2O8) was 99.1% in the range of 300K to 923K.

[0022] Figure 4The total heat leakage of specific implementation cases is explained. In the total heat leakage diagram of Scheme A, the micro-protrusion material of the low-temperature side insulation layer used in Examples 1-6 is closed-cell polyurethane foam block; the micro-protrusion material of the high-temperature side insulation layer in Examples 1-3 is zirconium tungstate; and the micro-protrusion material of the high-temperature side insulation layer in Examples 4-6 is zirconium tungstate composite material, while the structure of the micro-protrusions is changed. The difference between Scheme B and Scheme A is that the total number of layers is changed, with the number of layers of the low-temperature side insulation layer increasing by 10. Examples 7-12 correspond one-to-one with the examples of Scheme A. Scheme C also changes the total number of layers compared to Schemes B and A, with the number of layers of the low-temperature side insulation layer increasing to 20 and the number of layers of the high-temperature side insulation layer increasing to 30. Examples 13-18 correspond one-to-one with Schemes A and B.

[0023] The following are specific embodiments of multilayer thermal insulation material structures with different micro-protrusions.

[0024] Option A. The total number of layers in the micro-protrusion multilayer ultra-low temperature composite thermal insulation structure is 30: 10 layers of thermal insulation layer on the low temperature side, 20 layers of thermal insulation layer on the high temperature side, the base layer is polyester film, and the reflective layer is aluminum foil.

[0025] Example 1. The low-temperature side insulation layer uses a micro-protrusion structure: a square cross-section with a side length of 0.5 mm and a height of 0.6 mm, and the distance between the two innermost adjacent low-temperature side micro-protrusions is 2.0 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 30 kg / m³. The high-temperature side insulation layer also uses a micro-protrusion structure: a square cross-section with a side length of 0.5 mm and a height of 0.6 mm, made of ZrW2O8 material. The total thickness of each layer of the low-temperature side insulation structure is 1.1 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.2 mm. The total mass of the multi-layer ultra-low temperature composite insulation structure with micro-protrusions is 20.1 kg, and the total heat leakage value is 20.32 W.

[0026] Example 2. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 1.0 mm and a height of 1.2 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.2 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 40 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 1.0 mm and a height of 1.2 mm, made of zirconium tungstate (ZrW₂O₈). The total thickness of each layer of the low-temperature side insulation structure is 1.5 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.7 mm. The total mass of the multi-layer micro-protrusion cryogenic composite insulation structure is 25.2 kg, and the total heat leakage value is 18.59 W.

[0027] Example 3. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.5 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.5 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 50 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.5 mm, made of zirconium tungstate (ZrW₂O₈). The total thickness of each layer of the low-temperature side insulation structure is 2 mm, and the total thickness of each layer of the high-temperature side insulation structure is 2.2 mm. The total mass of the multi-layer micro-protrusion ultra-low temperature composite insulation structure is 31.7 kg, and the total heat leakage value is 9.48 W.

[0028] Example 4. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 0.6 mm and a height of 0.5 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.0 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 30 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 0.6 mm and a height of 0.5 mm, using zirconium tungstate composite material (filled with 40% alumina ceramic). The total thickness of each layer of the low-temperature side insulation structure is 1 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.2 mm. The total mass of the multi-layer micro-protrusion cryogenic composite insulation structure is 19.7 kg, and the total heat leakage value is 31.32 W.

[0029] Example 5. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.0 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.0 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 40 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.0 mm, using zirconium tungstate composite material (filled with 50% alumina ceramic). The total thickness of each layer of the low-temperature side insulation structure is 1.5 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.7 mm. The total mass of the multi-layer micro-protrusion cryogenic composite insulation structure is 23.5 kg, and the total heat leakage value is 23.51 W.

[0030] Example 6. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 1.5 mm and a height of 1.5 mm, and a spacing of 3.0 mm between the innermost two adjacent low-temperature side micro-protrusions. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 50 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 1.5 mm and a height of 1.5 mm, using zirconium tungstate composite material (filled with 60% alumina ceramic). The total thickness of each layer of the low-temperature side insulation structure is 2.0 mm, and the total thickness of each layer of the high-temperature side insulation structure is 2.2 mm. The total mass of the multi-layer micro-protrusion cryogenic composite insulation structure is 30.74 kg, and the total heat leakage value is 14.82 W.

[0031] Option B. The total number of layers of the micro-protrusion multilayer ultra-low temperature composite thermal insulation structure is 40: 20 layers of thermal insulation layer on the low temperature side, 20 layers of thermal insulation layer on the high temperature side, the base layer is glass fiber paper, and the reflective layer is aluminum foil.

[0032] Example 7. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 0.5 mm and a height of 0.6 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.0 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 30 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 0.5 mm and a height of 0.6 mm, made of zirconium tungstate (ZrW₂O₈). The total thickness of each layer of the low-temperature side insulation structure is 1.1 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.2 mm. The total mass of the multi-layer micro-protrusion ultra-low temperature composite insulation structure is 22.53 kg, and the total heat leakage value is 17.3 W.

[0033] Example 8. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 1.0 mm and a height of 1.2 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.4 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 30 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 1.0 mm and a height of 1.2 mm, made of zirconium tungstate (ZrW₂O₈). The total thickness of each layer of the low-temperature side insulation structure is 1.5 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.7 mm. The total mass of the multi-layer micro-protrusion cryogenic composite insulation structure is 27.41 kg, and the total heat leakage value is 16.32 W.

[0034] Example 9. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.5 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.6 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 50 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.5 mm, made of zirconium tungstate (ZrW₂O₈). The total thickness of each layer of the low-temperature side insulation structure is 2 mm, and the total thickness of each layer of the high-temperature side insulation structure is 2.2 mm. The total mass of the multi-layer micro-protrusion ultra-low temperature composite insulation structure is 33.5 kg, and the total heat leakage value is 5.88 W.

[0035] Example 10. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 0.6 mm and a height of 0.5 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.0 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 30 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 0.6 mm and a height of 0.5 mm, using zirconium tungstate composite material (filled with 40% alumina ceramic). The total thickness of each layer of the low-temperature side insulation structure is 1 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.2 mm. The total mass of the multi-layer micro-protrusion ultra-low temperature composite insulation structure is 22.13 kg, and the total heat leakage value is 20.53 W.

[0036] Example 11. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.0 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.0 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 40 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.0 mm, using zirconium tungstate composite material (filled with 50% alumina ceramic). The total thickness of each layer of the low-temperature side insulation structure is 1.5 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.7 mm. The total mass of the multi-layer micro-protrusion ultra-low temperature composite insulation structure is 25.49 kg, and the total heat leakage value is 18.70 W.

[0037] Example 12. The low-temperature side insulation layer uses a micro-protrusion structure: a rectangle 1.5mm long and 1.5mm high, with a 3.0mm spacing between the innermost two adjacent low-temperature side micro-protrusions. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 40kg / m³. The high-temperature side insulation layer uses a micro-protrusion structure: a rectangle 1.5mm long and 1.5mm high, made of zirconium tungstate composite material (filled with 60% alumina ceramic). The total thickness of each layer of the low-temperature side insulation structure is 2.0mm, and the total thickness of each layer of the high-temperature side insulation structure is 2.2mm. The total mass of the multi-layer micro-protrusion ultra-low temperature composite insulation structure is 32.44kg, and the total heat leakage value is 7.34W.

[0038] Option C. The total number of layers in the micro-protrusion multilayer ultra-low temperature composite thermal insulation structure is 50: 20 layers of thermal insulation layer on the low temperature side, 30 layers of thermal insulation layer on the high temperature side, the base layer is polyester film, and the reflective layer is aluminum foil.

[0039] Example 13. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 0.5 mm and a height of 0.6 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.0 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 30 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 0.5 mm and a height of 0.6 mm, made of zirconium tungstate (ZrW₂O₈). The total thickness of each layer of the low-temperature side insulation structure is 1.1 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.2 mm. The total mass of the multi-layer micro-protrusion ultra-low temperature composite insulation structure is 25.37 kg, and the total heat leakage value is 15.26 W.

[0040] Example 14. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 1.0 mm and a height of 1.2 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.2 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 30 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 1.0 mm and a height of 1.2 mm, made of zirconium tungstate (ZrW₂O₈). The total thickness of each layer of the low-temperature side insulation structure is 1.5 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.7 mm. The total mass of the multi-layer micro-protrusion ultra-low temperature composite insulation structure is 30.35 kg, and the total heat leakage value is 13.77 W.

[0041] Example 15. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.5 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.5 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 50 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.5 mm, made of zirconium tungstate (ZrW₂O₈). The total thickness of each layer of the low-temperature side insulation structure is 2 mm, and the total thickness of each layer of the high-temperature side insulation structure is 2.2 mm. The total mass of the multi-layer micro-protrusion cryogenic composite insulation structure is 38.90 kg, and the total heat leakage value is 3.21 W.

[0042] Example 16. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 0.6 mm and a height of 0.5 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.0 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 30 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 0.6 mm and a height of 0.5 mm, using zirconium tungstate composite material (filled with 40% alumina ceramic). The total thickness of each layer of the low-temperature side insulation structure is 1 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.2 mm. The total mass of the multi-layer micro-protrusion cryogenic composite insulation structure is 24.09 kg, and the total heat leakage value is 16.19 W.

[0043] Example 17. The low-temperature side insulation layer features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.0 mm. The distance between the two innermost adjacent low-temperature side micro-protrusions is 2.5 mm. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 40 kg / m³. The high-temperature side insulation layer also features a micro-protrusion structure: a square cross-section with a side length of 1.2 mm and a height of 1.0 mm, using zirconium tungstate composite material (filled with 50% alumina ceramic). The total thickness of each layer of the low-temperature side insulation structure is 1.5 mm, and the total thickness of each layer of the high-temperature side insulation structure is 1.7 mm. The total mass of the multi-layer micro-protrusion cryogenic composite insulation structure is 28.44 kg, and the total heat leakage value is 14.25 W.

[0044] Example 18. The low-temperature side insulation layer uses a micro-protrusion structure: a rectangle 1.5mm long and 1.5mm high, with a 3.0mm spacing between the innermost two adjacent low-temperature side micro-protrusions. The low-temperature side micro-protrusions are closed-cell polyurethane foam blocks with a density of 50kg / m³. The high-temperature side insulation layer uses a micro-protrusion structure: a rectangle 1.5mm long and 1.5mm high, made of zirconium tungstate composite material (filled with 60% alumina ceramic). The total thickness of each layer of the low-temperature side insulation structure is 2.0mm, and the total thickness of each layer of the high-temperature side insulation structure is 2.2mm. The total mass of the multi-layer micro-protrusion cryogenic composite insulation structure is 27.82kg, and the total heat leakage value is 5.49W.

Claims

1. A micro-protruding multilayer ultra-low temperature composite insulation structure, comprising a low-temperature side insulation layer structure near the cold end and a high-temperature side insulation layer structure near the hot end, wherein the entire insulation structure is vacuum-sealed, the low-temperature side insulation layer structure encapsulates a tank containing a cryogenic liquid working fluid, and the high-temperature side insulation layer structure encapsulates the low-temperature side insulation layer structure; characterized in that: Both the low-temperature side insulation layer structure and the high-temperature side insulation layer structure are layered structures; the low-temperature side insulation layer structure includes 10 to 20 spacer layers, and the high-temperature side insulation layer structure includes 20 to 30 spacer layers; the spacer layer includes a base layer and a reflective layer attached to the base layer, with the reflective layer located on the side of the spacer layer facing the hot end. A micro-protrusion structure layer is provided between adjacent spacer layers. The micro-protrusion structure layer is composed of multiple micro-protrusions. Among them, the multiple micro-protrusions of the micro-protrusion structure layer closest to the cold end are arranged in a lattice. The micro-protrusions of the other micro-protrusion structure layers correspond to the radial projection positions of the innermost micro-protrusion. The micro-protrusions of the low-temperature side insulation layer are closed-cell polyurethane foam blocks with a density of 30-50 kg / m³; the micro-protrusions of the high-temperature side insulation layer are made of zirconium tungstate ZrW2O8 or zirconium tungstate composite material.

2. The micro-protrusion multilayer ultra-low temperature composite thermal insulation structure as described in claim 1, characterized in that: The base layer is a polyester film or fiberglass paper, and the reflective layer is an aluminum foil or copper foil.

3. The micro-protrusion multilayer ultra-low temperature composite thermal insulation structure as described in claim 1, characterized in that: The micro-protrusions are all cuboids whose orthographic projection is a square. The side length of the square is 0.5 to 1.5 mm, the height of the cuboid is 0.5 to 1.5 mm, and the distance between two adjacent innermost micro-protrusions is 2.0 to 3.0 mm.

4. The micro-protrusion multilayer ultra-low temperature composite thermal insulation structure as described in claim 1, characterized in that: The closed-cell polyurethane foam block has a thermal conductivity of 0.018–0.022 W / (m·K) and a coefficient of thermal expansion of 200 × 10⁻⁶. -6 ~500×10 -6 / K.

5. The micro-protrusion multilayer ultra-low temperature composite thermal insulation structure as described in claim 1, characterized in that: The aforementioned zirconium tungstate material has a coefficient of thermal expansion of -9.1 × 10⁻⁶ K at 300–923 K. -6 ~-7×10 -6 / K; The zirconium tungstate composite material is zirconium tungstate filled with ceramic material, with a filling amount of 40-60% of the total mass of the composite material, and a coefficient of thermal expansion of -1.2×10⁻⁶ K at 300-923 K. -6 ~1×10 -6 / K.

6. The micro-protrusion multilayer ultra-low temperature composite thermal insulation structure as described in claim 5, characterized in that: The ceramic material is alumina ceramic, with a coefficient of thermal expansion of 6.0 × 10⁻⁶ K between 300 and 923 K. -6 ~7.8×10 -6 / K.

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