A thermal insulation air membrane enclosure structure and method for buried hot water storage tanks

Abstract

This invention discloses a roof insulation air-supported membrane structure and method for a buried hot water storage tank, which solves the problem of environmental corrosion of the insulation layer in the prior art. It has the beneficial effects of avoiding external environmental corrosion of the foaming material and controlling heat loss. The specific solution is as follows: A roof insulation air-supported membrane structure for a buried hot water storage tank includes at least three layers of isolation membranes. The multiple layers of isolation membranes are laid sequentially on the top surface of the hot water storage tank. The periphery of the multiple layers of isolation membranes is fixed to the cofferdam of the hot water storage tank. The projected area of ​​each layer of isolation membrane on the horizontal plane is larger than the projected area of ​​the hot water storage tank on the horizontal plane. A first cavity is formed between two adjacent inner layers of isolation membranes. The first cavity is filled with gas with a set pressure to support the air-supported membrane structure. A second cavity is formed between the outermost isolation membrane and its inner isolation membrane. Multiple isolation chambers are set in the second cavity. Each isolation chamber is filled with foaming material. The air in the first cavity and the foaming material in the second cavity insulate the hot water storage tank.

Description

Technical Field

[0001] This invention relates to the field of hot water storage tank technology, and in particular to a top-insulated air-film enclosure structure and method for buried hot water storage tanks. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] A hot water storage tank is a container or structure used to store hot water. It is commonly found in industrial and civil buildings, solar water heating systems, and heating systems. Its main function is to regulate the balance between hot water supply and demand and ensure a stable water supply. The core of its working principle is that the low-temperature water at the bottom of the tank is pumped to a heat exchanger, where it exchanges heat with an external heat source (such as a heat pump, industrial waste heat, or solar energy) to increase its temperature, and then is transported back to the top of the tank. Utilizing the density difference of the water, a layered structure of "hot at the top and cold at the bottom" is formed, reducing the mixing of hot and cold water, thereby efficiently storing heat and supplying hot water or thermal energy to the energy-consuming end as needed.

[0004] As a core facility for regulating the balance of hot water supply and demand, the heat loss from the top of hot water storage tanks is a key issue affecting the stability of water supply and energy utilization. Current technologies use XPE (chemically cross-linked polyethylene) insulation layers on the top of hot water storage tanks, and structures such as membrane + insulation material (mainly XPE) + UV-resistant membrane. However, these technologies suffer from three major drawbacks: First, the insulation layer cannot be stably fixed, making the protective layer susceptible to environmental corrosion (such as rainwater and ultraviolet rays). It needs to be partially replaced every 3-5 years, and the water tank needs to be drained during maintenance, which may lead to water supply interruption. Secondly, the amount of heat loss is usually related to the thickness of the insulation layer, which is usually fixed and cannot be adjusted according to seasonal temperature changes. In winter, the heat loss rate can still reach 12%-18%. Third, the material cost of the insulation layer is relatively high, costing approximately 1000m³. 2 The initial investment exceeded 120,000 yuan. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a roof insulation air membrane enclosure structure for buried hot water storage tanks. This structure uses foamed material to form an insulation layer, and an isolation membrane supports and protects the foamed material, preventing it from being corroded by the environment and effectively extending its service life.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution: A roof insulation air-supported membrane structure for a buried hot water storage tank includes at least three layers of insulation membrane. The multiple layers of insulation membrane are laid sequentially on the top surface of the hot water storage tank. The periphery of the multiple layers of insulation membrane is fixed to the cofferdam of the hot water storage tank. The projected area of ​​each layer of insulation membrane in the horizontal plane is larger than the projected area of ​​the hot water storage tank in the horizontal plane. A first cavity is formed between two adjacent inner layers of insulation membrane. The first cavity is filled with gas at a set pressure to support the air-supported membrane structure. A second cavity is formed between the outermost layer of insulation membrane and its innermost layer of insulation membrane. Multiple isolation chambers are set in the second cavity. Each isolation chamber is filled with foam material. The air in the first cavity and the foam material in the second cavity insulate the hot water storage tank and reduce the heat loss rate.

[0007] As described above, the maximum spacing between two adjacent layers of the insulating membrane enclosure structure on the top of the buried hot water storage tank is between 0.4m and 0.7m.

[0008] As described above, in the buried hot water storage tank top insulation air membrane enclosure structure, the second cavity is formed by setting a vertical isolation membrane to form the isolation cavity. The vertical isolation membrane connects the outermost isolation membrane and the adjacent isolation membrane. The outermost isolation membrane is provided with a material injection hole at the corresponding position of the isolation cavity.

[0009] As described above, in the buried hot water storage tank top insulation air membrane enclosure structure, the first cavity is equipped with a first exhaust valve on the isolation membrane facing the hot water storage tank, and the second cavity is equipped with a second exhaust valve on the isolation membrane away from the hot water storage tank. Both the first exhaust valve and the second exhaust valve are connected to the control unit respectively.

[0010] As described above, in the buried hot water storage tank top insulation air membrane enclosure structure, a pressure sensor is installed on the side wall of the first cavity, and a temperature sensor is installed on the outside of the air membrane enclosure structure. The pressure sensor and the temperature sensor are respectively connected to the control unit. When the temperature is greater than or equal to 25°C, the control unit stores a first set pressure value and a second set pressure value. When the pressure sensor detects that the pressure value is greater than the first set pressure value, it controls the first exhaust valve to exhaust air. When the temperature sensor detects that the temperature T is between 0 and 25°C, the pressure index value is the second set pressure value - 0.02 × (T - 0) kPa. When the temperature is ≤ 0°C, the pressure index value is 0.8 kPa. When the pressure value is > 0.8 kPa, the control unit controls the first exhaust valve to exhaust air.

[0011] As described above, the top insulation air membrane enclosure structure of a buried hot water storage tank has three layers of isolation membrane, which are arranged from the inside out as a first isolation membrane, a second isolation membrane, and a third isolation membrane. The longitudinal cross-section of each isolation membrane is arc-shaped. The center-to-center distance and side-to-side contact of adjacent isolation membranes increase sequentially from the inside out.

[0012] As described above, in the buried hot water storage tank top insulation air membrane enclosure structure, the unfolded area of ​​the isolation membrane is determined based on the unfolded area of ​​the membrane surface, the edge coverage area, and the splicing and fixing allowance. The unfolded area of ​​the membrane surface is determined based on the length of the hot water storage tank, the width of the hot water storage tank, the maximum height between the water surface and the corresponding isolation membrane, and the central angle of the isolation membrane. The edge coverage area is determined based on the length of the hot water storage tank and the width of the hot water storage tank.

[0013] As described above, in a buried hot water storage tank, the edges of two adjacent layers of insulation membrane are welded together. A support block is fixed at the embankment and embedded in the embankment. The support block has a groove, and the edge of the air membrane enclosure structure is placed in the groove. A compacted stone slab is placed above the edge of the air membrane enclosure structure, and fasteners pass through the compacted stone slab and are sealed to the support block.

[0014] As described above, a top-insulated air-film enclosure structure for a buried hot water storage tank includes a flexible barrier layer along the sidewalls and bottom of the hot water storage tank. The foaming material is rigid polyurethane foam, and the material of the separator is coated polyester fiber.

[0015] As described above, the buried hot water storage tank has a roof insulation air membrane enclosure structure, wherein the air membrane enclosure structure is provided with an openable entrance door, and the first cavity is connected to a blower.

[0016] Secondly, the present invention also provides a method for heat preservation of a hot water storage tank, comprising the following: An insulated air-film enclosure structure for the top of a buried hot water storage tank is installed at the hot water storage tank location; Air is introduced into the first cavity to support the air-supported membrane structure; Foaming material is introduced into each isolation cavity to form a foaming material layer; A pressure sensor is installed in the first chamber. If the pressure difference is less than ±0.02 kPa within a set time, it indicates that the airtightness is good.

[0017] The beneficial effects of the present invention are as follows: This invention utilizes an air-supported membrane enclosure structure. Gas is introduced into the first cavity, and foamed material is introduced into the second cavity, forming a top-mounted air-supported insulation membrane enclosure structure. The bottom air cavity not only supports the entire air-supported membrane enclosure structure but also supports the foamed material layer from below, protecting and shielding the foamed material (as an insulation layer) and preventing external environmental corrosion. Utilizing the principle of "air layer and foamed material insulation," the heat from the hot water storage tank is transferred away through multiple layers of insulation membrane, air cavity, and foamed material, reducing the heat loss rate to below 5%. The combination of the air layer and foamed material effectively controls the thickness of the foamed material, resulting in a 25% reduction in initial costs, an extended maintenance cycle of 8-10 years, and no need for downtime maintenance, effectively improving the economy and stability of the hot water storage tank. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 This is a schematic diagram of a roof insulation air membrane enclosure structure for a buried hot water storage tank according to one or more embodiments of the present invention.

[0020] Figure 2 This is a top view of a buried hot water storage tank top insulation air membrane enclosure structure according to one or more embodiments of the present invention.

[0021] Figure 3 This is a cross-sectional view of a roof insulation air membrane enclosure structure for a buried hot water storage tank according to one or more embodiments of the present invention.

[0022] Figure 4 This is a cross-sectional view of the three-layer isolation membrane in the top heat-insulating air-film enclosure structure of a buried hot water storage tank according to one or more embodiments of the present invention.

[0023] Figure 5 This is a schematic diagram of the connection between the support block and the multi-layer isolation membrane in a top thermal insulation air membrane enclosure structure of a buried hot water storage tank according to one or more embodiments of the present invention.

[0024] Figure 6 This is a flowchart illustrating the adjustment process of a buried hot water storage tank top insulation air membrane enclosure structure according to one or more embodiments of the present invention.

[0025] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0026] The components include: 1. Hot water storage tank; 2. Air-supported membrane structure; 3. Entrance door; 4. Blower; 5. First isolation membrane; 6. Second isolation membrane; 7. Third isolation membrane; 8. Second cavity; 9. First cavity; 10. Flexible barrier layer; 11. Cofferdam; 12. Support block; 13. Compacted stone slab; 14. First exhaust valve; 15. Second exhaust valve; 16. Anchor bolts. Detailed Implementation

[0027] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0028] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, unless otherwise expressly indicated by the invention, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. As described in the background section, the insulation layer of existing hot water storage tanks is prone to corrosion. In order to solve the above-mentioned technical problem, this invention proposes a top insulation air membrane enclosure structure for buried hot water storage tanks.

[0029] Example 1 In a typical embodiment of the present invention, reference is made to Figure 1 As shown, a buried hot water storage tank top insulation air membrane enclosure structure includes at least three layers of insulation membrane. The multiple layers of insulation membrane are laid sequentially on the top surface of the hot water storage tank 1. The periphery of the multiple layers of insulation membrane is fixed to the cofferdam 11 of the hot water storage tank 1. The projected area of ​​each layer of insulation membrane in the horizontal plane is larger than the projected area of ​​the hot water storage tank 1 in the horizontal plane. A first cavity 9 is formed between two adjacent inner layers of insulation membrane. The first cavity 9 is filled with gas at a set pressure to form a gas layer, thereby supporting the air membrane enclosure structure 2. A second cavity 8 is formed between the outermost layer of insulation membrane and its inner layer of insulation membrane. Multiple isolation chambers are set in the second cavity 8. Each isolation chamber is filled with foam material. The air in the first cavity and the foam material in the second cavity 8 insulate the hot water storage tank 1 and reduce the heat loss rate.

[0030] The air-supported membrane enclosure structure provided in this embodiment has gas introduced into the first cavity 9 and foamed material introduced into the second cavity 8, forming a top-supported air-supported insulation membrane enclosure structure. The air cavity on the bottom not only supports the entire air-supported membrane enclosure structure, but also supports the foamed material layer from below, protecting and protecting the foamed material (as an insulation layer) and preventing external environmental corrosion of the foamed material. Utilizing the principle of "air layer and foamed material insulation," the heat from the hot water storage tank 1 can only be transferred out through multiple layers of insulation membrane, air cavity, and foamed material, effectively controlling the heat loss rate. With the air layer and foamed material working together, under the premise of controlling the heat loss rate, there is no need to make the foamed material too thick, effectively controlling costs.

[0031] In this regard, considering the overall thickness, while meeting the requirements and controlling costs, the maximum spacing between two adjacent layers of the isolation film is between 0.4m and 0.7m, preferably 0.5m, so as to control the amount of foaming material.

[0032] In this embodiment, the isolation membrane is provided with three layers, from the inside out, namely the first isolation membrane 5, the second isolation membrane 6 and the third isolation membrane 7. The longitudinal cross-section of each isolation membrane is arc-shaped. The center-to-center distance and side-to-side contact of adjacent isolation membranes increase sequentially from the inside out.

[0033] It should be noted that the first and second isolation membranes 5 and 6 are made of PVC (polyvinyl chloride) coated polyester fiber, which has excellent airtightness and can effectively prevent hot air from escaping from the hot water storage tank 1. It can withstand ambient temperatures of -10 to 60℃, with a thickness of 0.5–0.6 mm and a thermal conductivity of 0.14 W / (m·K). This material is used for airtightness, flexibility, and ease of molding. The third isolation membrane 7 is made of PVDF (polyvinylidene fluoride) coated polyester fiber, which has strong weather resistance, can withstand ambient temperatures of -30 to 70℃, resists UV aging, and has a certain impact resistance. Its thickness is 0.7–0.8 mm and its thermal conductivity is 0.17 W / (m·K). To enhance wind resistance and aging resistance and ensure long-term outdoor stability, the vertical membranes also use the same material. The foaming material used in the foaming layer between the second and third isolation membranes 6 is rigid polyurethane foam with a density of 28–50 kg / m³. 3 The thermal conductivity is 0.022~0.028W / (m·K), and the thickness is 0.5m.

[0034] refer to Figure 4As shown, an air cavity is formed between the first isolation membrane 5 and the second isolation membrane 6, and a second cavity 8 is formed between the second isolation membrane 6 and the third isolation membrane 7. The vertical isolation membrane in the second cavity must be firmly fixed and the seams sealed to prevent material from flowing through during foaming. An injection hole is reserved at the top of each small cavity, and the hole diameter is adapted to the injection gun head. The injection hole is located at the center or diagonal of each grid. Insert the injection gun into the injection hole, reaching the bottom of the cavity. Lightly spray the interface primer to enhance the adhesion between the foam and the release liner, preventing delamination and voids. Pour in layers of 20-30mm thickness, waiting for each layer to fully cure before applying the next layer. The foam will begin to expand and naturally fill the gaps a few seconds after pouring. Wait for it to fully harden before proceeding to the next step. Finally, after each layer has cured, manually trim the edges and corners, and smooth the curved surfaces to ensure uniform thickness. During injection, use layered, quantitative pouring, with each injection not exceeding 70% of the cavity volume to prevent foam overflow or damage to the vertical release liner due to excessive pressure. Immediately after injection, seal the injection hole, allowing the foam material to expand freely and fill the space within the sealed cavity. Wait for the foam to initially expand and solidify (approximately 5-10 minutes), observing the filling status of each cell: if there are depressions or voids, inject a small amount of material through the pre-drilled hole; if there is overflow, cut off the excess after the foam has solidified. It should be noted that the unfolded areas of the first isolation membrane 5, the second isolation membrane 6, and the third isolation membrane 7 need to be determined based on the horizontal projected area of ​​the water surface at the top of the pool, the edge coverage area, and the splicing and fixing allowance. The specific formula is as follows (1): (1) In the formula: —The unfolded area of ​​the membrane (since the membrane is curved, the calculation is based on the area of ​​the curve), where the number in □ represents which layer of the separator membrane; —Edge coverage area (extending outwards 2m from the top of the pool, area = pool perimeter × 2m) —Splicing and fixing allowance (calculated as 5% of the sum of S1+S2, used for welding loss and support fixing), where the number in □ represents which layer of the isolation membrane.

[0035] Specifically, the unfolded area of ​​the membrane is determined based on the length of the hot water storage tank 1, the width of the hot water storage tank 1, the maximum height between the water surface and the corresponding isolation membrane, and the central angle of the isolation membrane. The edge coverage area is determined based on the length of the hot water storage tank 1 and the width of the hot water storage tank 1.

[0036] The specific formula for determining the central angle of the separator is as follows (2): (2) In the formula: —Central angle of the separator, rad — Arch chord length, m —Radius of the arc, m Assuming the top surface of the hot water storage tank is a rectangular pool with a length of 50m and a width of 20m, the water surface is 3m above the inner first isolation membrane 5, and the thickness of the air cavity is 1m, including an air layer with a maximum thickness of 0.5m and a foam material layer with a thickness of 0.5m, the required dimensions for the transverse air membrane (arched along the long side) are calculated as follows: For the first separating membrane 5, the radius of the arc If the central angle θ = 0.47 rad, then the inner arc length L = R 11 ×θ = 105.7 × 0.47 = 49.7 m, then S 11 =49.7×20=994m 2 Similarly, for the second isolation membrane 6, the radius of the arc R 12 =105.7 + 0.5 = 106.2m, central angle θ = 0.47 rad, then the inner arc length L = R 12 ×θ=106.2×0.47=49.9m, then S 12 =49.9×20=998m 2 Similarly, for the third separating membrane 7, the radius of the arc R 31 =105.7 + 1 = 106.7 m, central angle θ = 0.47 rad, then the inner arc length L = R 13 ×θ = 106.7 × 0.47 = 50.1 m, then S 13 =50.1×20=1002m 2 And S2 = (50 + 20) × 2 × 2 = 280m 2 S 31 = (994 + 280) × 5% = 63.7m 2 S 32 = (998 + 280) × 5% = 63.9m 2 S 33 = (994 + 280) × 5% = 63.7m 2 .

[0037] According to calculations, the first separator 5 requires 1337.7m. 2 The second separator membrane 6 requires 1341.9m in size. 2 The third separator membrane (7) requires 1346.1m in size. 2 The dimensions are as follows; and an entrance door 3 is connected to one side of the air-supported membrane structure 2, which is 2cm away from the interior of the hot water storage tank, making it convenient for maintenance personnel to enter and check the condition of the air-supported membrane.

[0038] Figure 3 This is a cross-sectional view along the length of the air-supported membrane structure. The hot water storage tank 1 is inverted T-shaped. A flexible barrier layer 10 is installed on the side of the hot water storage tank 1, which is in contact with the soil. A dike 11 is installed around the hot water storage tank 1 to prevent water overflow. The dike 11 includes a flat section and an outer inclined section, with the outer inclined section connected to the flat section. The first isolation membrane 5 is close to the hot water storage tank. The first isolation membrane 5 and the third isolation membrane 7 together define the interlayer space air cavity. By inflating and pouring foaming material, the air cavity is divided into a gas layer and a foaming material layer. The second isolation membrane 6 is located between the gas layer and the foaming material layer. After a period of operation... After a period of time, a large amount of gas will be generated above the water surface and in the gas layer. At this time, the gas can be vented. Therefore, a first vent valve 14 and a second vent valve 15 are set at the first isolation membrane and the third isolation membrane. When the pressure exceeds the set pressure, the first vent valve 14 of the first isolation membrane will vent the gas above the water surface. The first vent valve is connected to the air pipe. The air pipe passes through the second isolation membrane and the third isolation membrane and is in sealed contact with these two isolation membranes. The air pipe can be connected to the air pump. The second vent valve 15 of the third isolation membrane will vent the gas in the gas layer. The air membrane enclosure structure 2 is fixed on both sides using compacted stone slabs 13.

[0039] It is easy to understand that the hot water storage tank 1 can be square, circular, or other irregular shapes. Considering factors such as construction difficulty and cost, the preferred shape of the hot water storage tank is determined. One preferred shape is an inverted pyramid shape with the top removed.

[0040] refer to Figure 3 and Figure 4 As shown, after inflation, the air-supported membrane structure 2 will bulge to form an arch. The isolation membrane is fixed by a groove compaction method. Support blocks are set on the plane of the cofferdam 11, and support blocks 12 are embedded in the cofferdam 11. The support blocks 12 have grooves. The edges of the isolation membrane are compacted and fixed by compaction stone slabs 13. The groove is an inverted trapezoid, and the width of the compaction stone slabs 13 is adapted to the size of the bottom side of the groove. Starting from one end of the groove, the edge of the isolation membrane is pressed into the groove. Rubber sealing strips are used. The sealing strips are placed between two adjacent isolation membranes. The air membrane is evenly pressed to the bottom of the groove in sections to avoid local wrinkles. Stainless steel pressure strips are placed in the groove to press the air membrane and sealing strips. The pre-embedded bolt holes are aligned, and anchor bolts 16 are installed. The anchor bolts 16 pass through the compaction stone slabs 13, multiple layers of isolation membrane, stainless steel pressure strips and sealing strips and are pre-tightened. This completes the fixing of the edge of the air-supported membrane structure. The air tightness of the air-supported membrane structure is ensured by the setting of stainless steel pressure strips and sealing strips. refer to Figure 3As shown, the bottom of the support block 12 is embedded in the cofferdam 11. The width of the support block 12 is less than the width of the cofferdam plane section. The distance between the inner surface of the support block 12, i.e. the inner surface facing the hot water storage tank 1, and the inner edge of the top of the hot water storage tank 1 is generally between 0.3m and 0.5m, so that there is room for workers to stand after entering, and to prevent workers from falling into the hot water storage tank.

[0041] In addition, considering that rainwater will accumulate in the grooves when it rains, rainwater drainage outlets and drainage pipes are installed on both sides of the air-supported membrane structure 2 to solve the problem of rainwater accumulation.

[0042] Furthermore, a pressure sensor is installed on the side wall of the first cavity, and a temperature sensor is installed on the outside of the air-supported membrane structure. The pressure sensor and the temperature sensor are respectively connected to the control unit. The control unit is a PLC controller or other type of controller. When the temperature is greater than or equal to 25°C, the control unit stores a first set pressure value and a second set pressure value. When the pressure sensor detects that the pressure value is greater than the first set pressure value, it controls the first exhaust valve to exhaust air. When the temperature sensor detects that the temperature T is between 0 and 25°C, the pressure index value is the second set pressure value - 0.02 × (T - 0) kPa. When the temperature is ≤ 0°C, the pressure index value is 0.8 kPa. When the pressure value is > 0.8 kPa, the control unit controls the first exhaust valve to exhaust air.

[0043] In this embodiment, the total heat transfer loss of the air-supported membrane structure is calculated: When the air chamber is filled with air, the thickness of the first insulating membrane is δ1 = 0.5 mm, and its thermal conductivity is λ1 = 0.14 W / (m·K); the thickness of the second insulating membrane is δ2 = 0.5 mm, and its thermal conductivity is λ2 = 0.14 W / (m·K); the thickness of the third insulating membrane is δ3 = 0.7 mm, and its thermal conductivity is λ3 = 0.17 W / (m·K). The thermal conductivity of air is λ. air =0.026 W / (m·K), the thickness of the air layer inside the air cavity is δ air =0.5m, the thickness of the foamed material layer is δ4=0.5m, the thermal conductivity is λ4=0.022W / (m·K), and the convective heat transfer coefficient of the inner membrane is h1=5W / (m 2 •K); Assume that when the outdoor wind speed is v=3m / s, the external membrane convective heat transfer coefficient is h2=15W / (m²). 2 ·K), ambient temperature t f =-10℃, water temperature t w =50℃.

[0044] The heat transfer process of the entire air-supported membrane enclosure can be divided into three stages: the outer side—convection and radiation between the third insulating membrane and the external environment; the inner air cavity—conduction and convection; and the first insulating membrane—convection between the inner membrane and the water tank. Analysis shows that this heat transfer process involves series thermal resistance, therefore the total thermal resistance is... R total The overall heat transfer coefficient is the sum of all thermal resistances, expressed by the following formula (3): (3) Among them, the thermal resistance of the first insulating membrane is... The first insulating membrane has convective thermal resistance. The thermal resistance of the second insulating membrane The second insulating membrane has convective thermal resistance. The third insulating membrane has convective thermal resistance. The third insulating membrane has high thermal conductivity and thermal resistance. Thermal resistance of air in the air cavity Thermal resistance within the air cavity foam material layer Then the total thermal resistance

[0045] Total heat loss Therefore, substituting the data, we get... , , ,

[0046] ,

[0047] , (Because the air cavity takes into account the convection process, the thermal conductivity should be greater than 0.026) Total thermal resistance

[0048] heat transfer coefficient

[0049] Because of the different membrane areas, series heat transfer requires the logarithmic average area.

[0050] The total heat transfer loss is .

[0051] The calculations above show that the total heat transfer loss is 2.0kW, which is very low.

[0052] The air-supported membrane provided in this embodiment can cover any size of water area, from hundreds to tens of thousands of square meters, through welding. The dimensions of the air-supported membrane enclosure structure are pre-stressed for expansion, adapting to different water level changes and terrain undulations. Its adaptability to irregular water areas is far superior to rigid covers with fixed shapes. The PVDF-coated polyester fiber used in the membrane material has strong weather resistance, a service life of 15-20 years, and is recyclable. During operation, only a small amount of electricity is needed to drive the inflation equipment, with no exhaust emissions, making it more in line with low-carbon and environmentally friendly requirements than traditional covering methods. The air chamber and foam material layer work together to form a double-layer air-supported membrane enclosure structure, providing protection and buffering. The first isolation membrane acts as the main support layer to ensure core functions, while the second isolation membrane separates the two chambers and supports the foam layer, ensuring stable operation with heat preservation and airtightness. The third isolation membrane can withstand external impacts. In terms of functional expandability and economy, the air chamber and foam material layer can also serve as insulation layers, reducing heat exchange between the water area and the outside environment.

[0053] Example 2 This embodiment provides a method for heat preservation of a hot water storage tank, including the following: First, based on the top dimensions of the hot water storage tank, cut the first, second, and third isolation membranes accordingly, leaving a 5-8cm welding allowance at the cut edges. Then, align and stack them together, and weld them using a high-frequency heat sealing machine equipped with double rollers. After welding, use the "air tightness test method" (inflate one side of the weld seam with a pressure of 0.2kPa for 60 minutes, and observe whether bubbles are generated on the other side) to ensure that there is no leakage at the weld seam. After welding, fix the side of the air membrane enclosure structure to the cofferdam at point 11. Start the blower, and outside air is blown into the first chamber 9 through blower 4, thereby fully supporting the entire air film; then pour the concrete into each isolation chamber, with a pre-reserved injection hole at the top of each isolation chamber, the diameter of which is adapted to the injection gun head; refer to Figure 6 As shown, a pressure sensor is installed in the first chamber. When the blower is started to inflate the membrane, if the pressure difference within a set time is less than ±0.02 kPa, it indicates good air tightness. The pressure sensor monitors the membrane pressure in real time. When the pressure rises to 0.2 kPa, the blower is turned off, and the pressure is kept stable for 60 minutes (ensuring the membrane is fully expanded, without local wrinkles, and indicating good air tightness). If the pressure fluctuation within 60 minutes is less than ±0.02 kPa, it is determined that the membrane has been fully expanded, and the system switches to "operating pressure adjustment mode". If the fluctuation is too large, it prompts manual inspection of the membrane for leakage.

[0054] In summer (temperature ≥ 25℃), the pressure index value is 0.5 kPa. When the temperature rises and the air pressure inside the isolation membrane exceeds 0.5 kPa, the control unit controls the first exhaust valve to exhaust air to maintain pressure stability. In the transitional season (temperature 0~25℃), the pressure index value P0 is 0.8-0.02×(T-0) kPa, showing a linear change. In winter (temperature ≤ 0℃), the pressure index value is 0.8 kPa. When the pressure is > 0.8 kPa, the control unit controls the first exhaust valve to exhaust air.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A roof insulation air-supported membrane enclosure structure for a buried hot water storage tank, characterized in that, It includes at least three layers of insulating membrane. The multiple insulating membranes are laid sequentially on the top surface of the hot water storage tank. The periphery of the multiple insulating membranes is fixed to the cofferdam of the hot water storage tank. The projected area of ​​each insulating membrane on the horizontal plane is larger than the projected area of ​​the hot water storage tank on the horizontal plane. A first cavity is formed between two adjacent inner insulating membranes. The first cavity is filled with gas at a set pressure to support the air membrane enclosure structure. A second cavity is formed between the outermost insulating membrane and its inner insulating membrane. Multiple insulating chambers are set in the second cavity. Each insulating chamber is filled with foam material. The air in the first cavity and the foam material in the second cavity insulate the hot water storage tank.

2. The insulated air-film enclosure structure for the top of a buried hot water storage tank according to claim 1, characterized in that, The maximum spacing between two adjacent layers of the isolation membrane is between 0.4m and 0.7m.

3. The insulated air-supported membrane enclosure structure for the top of a buried hot water storage tank according to claim 1, characterized in that, The second cavity is formed by setting a vertical isolation membrane. The vertical isolation membrane connects the outermost isolation membrane and the adjacent isolation membrane. The outermost isolation membrane has an injection hole at the corresponding position of the isolation cavity.

4. The insulated air-supported membrane enclosure structure for the top of a buried hot water storage tank according to claim 1, characterized in that, The first chamber has a first exhaust valve installed on the isolation membrane facing the hot water storage tank, and the second chamber has a second exhaust valve installed on the isolation membrane away from the hot water storage tank. Both the first and second exhaust valves are connected to the control unit.

5. The insulated air-supported membrane enclosure structure for the top of a buried hot water storage tank according to claim 1, characterized in that, A pressure sensor is installed on the side wall of the first cavity, and a temperature sensor is installed on the outside of the air-supported membrane structure. The pressure sensor and the temperature sensor are respectively connected to the control unit. When the temperature is greater than or equal to 25°C, the control unit stores a first set pressure value and a second set pressure value. When the pressure sensor detects that the pressure value is greater than the first set pressure value, it controls the first exhaust valve to exhaust air. When the temperature sensor detects that the temperature T is between 0 and 25°C, the pressure index value is the second set pressure value - 0.02 × (T - 0) kPa. When the temperature is ≤ 0°C, the pressure index value is 0.8 kPa. When the pressure value is > 0.8 kPa, the control unit controls the first exhaust valve to exhaust air.

6. The insulated air-film enclosure structure for the top of a buried hot water storage tank according to claim 1, characterized in that, The isolation membrane has three layers, from the inside out: a first isolation membrane, a second isolation membrane, and a third isolation membrane. The longitudinal cross-section of each isolation membrane is arc-shaped. The center-to-center distance and side-to-side contact between adjacent isolation membranes increase sequentially from the inside out.

7. The insulated air-supported membrane enclosure structure for the top of a buried hot water storage tank according to claim 1, characterized in that, The unfolded area of ​​the isolation membrane is determined based on the unfolded area of ​​the membrane surface, the edge coverage area, and the splicing and fixing allowance. The unfolded area of ​​the membrane surface is determined based on the length of the hot water storage tank, the width of the hot water storage tank, the maximum height between the water surface and the corresponding isolation membrane, and the central angle of the isolation membrane. The edge coverage area is determined based on the length of the hot water storage tank and the width of the hot water storage tank.

8. The insulated air-film enclosure structure for the top of a buried hot water storage tank according to claim 1, characterized in that, The edges of two adjacent isolation membranes are welded together, and a support block is fixed at the cofferdam. The support block is embedded in the cofferdam and has a groove. The edge of the air-supported membrane structure is placed in the groove, and the compacted stone slab is placed above the edge of the air-supported membrane structure. Fasteners pass through the compacted stone slab and are sealed to the support block.

9. The insulated air-supported membrane enclosure structure for the top of a buried hot water storage tank according to claim 1, characterized in that, A flexible barrier layer is installed along the side walls and bottom of the hot water storage tank; The foaming material is rigid polyurethane foam, and the material of the separator is coated polyester fiber. The air-supported membrane enclosure structure is equipped with an openable entrance door, and the first chamber is connected to a blower.

10. A method for heat preservation of a hot water storage tank, characterized in that, Includes the following: An insulated air-film enclosure structure for the top of a buried hot water storage tank, as described in any one of claims 1-9, is provided at the hot water storage tank location; Air is introduced into the first cavity to support the air-supported membrane structure; Foaming material is introduced into each isolation cavity to form a foaming material layer; A pressure sensor is installed in the first chamber. If the pressure difference is less than ±0.02 kPa within a set time, it indicates that the airtightness is good.

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