A heat exchange system based on constant pressure compressed air energy storage

Abstract

The present invention relates to the technical field of air heat exchange, and discloses a heat exchange system based on constant pressure compressed air energy storage, including: a tunnel structure, consisting of an inclined shaft and a horizontal tunnel; the inclined shaft: connected to ground equipment, used for the transportation of compressed air; the horizontal tunnel: set deep underground, divided into a high temperature zone, a heat exchange zone and a cooling zone; the high temperature zone: located at one end of the horizontal tunnel, used to store the heat of compressed air, and the temperature is maintained at not less than 185°C; the heat exchange zone: located between the high temperature zone and the cooling zone, used for heat transfer and temperature regulation of compressed air and expanded air. By clearly dividing the high temperature zone, the heat exchange zone and the cooling zone, efficient heat transfer between compressed air and expanded air is achieved, and heat loss is significantly reduced; the use of high-efficiency heat storage materials and enhanced inner surface heat exchange devices further improves the efficiency of heat transfer and storage, so that the entire system can achieve high efficiency and precision in thermal energy management.

Description

Technical Field

[0001] The present invention relates to the technical field of air heat exchange, and in particular to a heat exchange system based on constant pressure compressed air energy storage. Background Art

[0002] With the rapid growth of global energy demand and the increasing attention to the use of renewable energy, energy storage technology has been widely studied and applied as an important means to solve the imbalance between energy supply and demand and improve energy efficiency. Compressed Air Energy Storage (CAES) has become one of the research hotspots of large-scale energy storage technology due to its advantages such as large scale, long life and environmental friendliness. Compressed air energy storage technology converts electrical energy into compressed air for storage and releases energy to generate electricity when needed, providing important support for power peak regulation, energy storage frequency regulation and stable power supply of renewable energy.

[0003] Existing compressed air energy storage technologies usually rely on heat storage tanks, cold storage tanks and heat exchangers to store and manage the heat of compressed air. These devices are usually located on the ground, occupy a lot of land resources, and have a long construction period. Taking large-scale energy storage projects as an example (such as 3300MW), dozens of large heat storage tanks and cold storage tanks with a diameter of 25 meters are usually required. These devices require complex construction processes and high maintenance costs. In addition, the heat management efficiency in existing systems is low, and the heat released by compressed air is often difficult to store and recover efficiently, resulting in a significant decrease in energy utilization.

[0004] However, existing compressed air energy storage systems have significant problems in heat management and equipment configuration. Especially for large-scale energy storage projects, the floor space and construction costs required for traditional heat storage tanks and cold storage tanks are extremely high, and the heat transfer efficiency during equipment operation is poor, resulting in a large amount of heat loss and energy waste. How to optimize the heat management efficiency while reducing construction costs and floor space has become a problem that needs to be urgently solved in the prior art. To this end, the present invention proposes a heat exchange system based on constant pressure compressed air energy storage, which effectively solves the problems of low heat management efficiency and large equipment footprint in the prior art through innovative tunnel structure design and functional zoning. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a heat exchange system based on constant pressure compressed air energy storage, which solves the problems of low heat management efficiency, high construction cost and large equipment footprint in the existing compressed air energy storage system.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions: A heat exchange system based on constant pressure compressed air energy storage, comprising:

[0007] Tunnel structure, consisting of inclined shafts and horizontal tunnels;

[0008] Inclined shaft: connected to the ground equipment and used for the transportation of compressed air;

[0009] Horizontal tunnel: set deep underground, divided into high temperature area, heat exchange area and cooling area;

[0010] High temperature zone: located at one end of the horizontal tunnel, used to store the heat of compressed air, with the temperature maintained at no less than 185°C;

[0011] Heat exchange area: located between the high temperature area and the cooling area, used for heat transfer and temperature regulation of compressed air and expanded air;

[0012] Cooling zone: located at the other end of the horizontal tunnel, used to cool the compressed air to the target temperature;

[0013] Gas transmission pipeline: runs through the high-temperature area, heat exchange area and cooling area, serving as the air inlet pipeline during compression and as the air outlet pipeline during expansion;

[0014] Multi-stage compression and expansion equipment is connected to the high temperature area, heat exchange area and cooling area through pipelines, and is used for storage and expansion of compressed air to generate electricity.

[0015] Preferably, the high temperature zone includes:

[0016] Thermal storage materials set in the tunnel wall to store and release heat;

[0017] The heat storage material is molten salt or high specific heat capacity metal.

[0018] Preferably, the heat exchange zone comprises:

[0019] A heat exchange device is arranged in the tunnel wall, wherein the heat exchange device is a heat exchange tube with a reinforced inner surface;

[0020] The heat exchange tube adjusts the temperature of the compressed air or the expanded air by convection and heat conduction.

[0021] Preferably, the cooling zone comprises:

[0022] A coolant circulation device arranged outside the tunnel wall is used to absorb the heat of the compressed air through the cooling medium;

[0023] The coolant is circulating water or industrial coolant.

[0024] Preferably, the multi-stage compression and expansion device comprises:

[0025] At least four-stage compressor, used to compress the air to a high pressure state step by step;

[0026] At least four stages of expanders are used to expand the air step by step and restore it to ambient pressure.

[0027] Preferably, the inner wall of the gas pipeline is coated with a heat-damage-resistant coating, and the pipeline diameter is dynamically adjusted according to pressure and temperature.

[0028] Preferably, the design parameters of the inclined well include:

[0029] The length of the inclined shaft is 6km to 10km;

[0030] The inclination of the inclined well is 10° to 20°;

[0031] The inner diameter is 6m to 10m.

[0032] Preferably, the layout of the horizontal tunnel can be adjusted to a vertical shaft or a curved tunnel.

[0033] Preferably, the length of the heat exchange zone is dynamically adjusted according to the power demand of the compressed air, and its length ranges from 20% to 60% of the total length of the tunnel.

[0034] Preferably, the heat storage material may be selected as metal oxide, and the cooling medium may be selected as ethylene glycol aqueous solution or liquid nitrogen.

[0035] The present invention provides a heat exchange system based on constant pressure compressed air energy storage. It has the following beneficial effects:

[0036] 1. The present invention realizes efficient heat transfer between compressed air and expanded air and significantly reduces heat loss by clearly dividing the high-temperature zone, heat exchange zone and cooling zone. The use of high-efficiency heat storage materials and enhanced inner surface heat exchange devices further improves the heat transfer and storage efficiency, making the entire system highly efficient and precise in thermal energy management.

[0037] 2. The present invention integrates the functions of traditional heat storage tanks and cold storage tanks into the tunnel structure, and adopts the design of underground inclined shafts and horizontal tunnels, which greatly reduces the footprint of ground equipment; modular construction simplifies the equipment installation and maintenance process, and compared with traditional designs, it saves about 1 billion yuan in costs, providing a more economical solution for large-scale energy storage projects.

[0038] 3. The tunnel design of the present invention adopts a flexible combination method, such as the diversified layout of inclined shafts and horizontal tunnels, vertical shafts and curved tunnels, which can adapt to various terrain conditions and complex working conditions; at the same time, it provides a variety of choices for heat storage materials and cooling media, which significantly improves the system's operating ability under special environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A top view of the tunnel of the present invention;

[0040] Figure 2 It is an enlarged view of the tunnel of the present invention;

[0041] Figure 3 It is a heat exchange schematic diagram of the present invention;

[0042] Figure 4 It is a schematic diagram of the heat exchange area of ​​the present invention. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Embodiment 1:

[0045] Please refer to the attached Figure 1 -Attached Figure 4 The embodiment of the present invention provides a heat exchange system based on constant pressure compressed air energy storage, which adopts a tunnel structure to replace traditional heat storage tanks, cold storage tanks and other equipment, integrates the heat management function into the inclined shaft and horizontal tunnel, realizes efficient compressed air heat transfer, storage and utilization, and has significant economy and adaptability.

[0046] The heat exchange system of the present invention is composed of the following parts:

[0047] 1.1 Tunnel structure The tunnel structure is the core of the heat exchange system, which consists of two parts: the inclined shaft and the horizontal tunnel:

[0048] inclined shaft:

[0049] Function: Connecting ground equipment (such as compressors and expanders) with underground tunnel heat exchange systems for the delivery of compressed air.

[0050] Design parameters: The length of the inclined shaft is 8km, the inclination is 16°, and the inner diameter is 8m; the inner wall of the inclined shaft is made of high-strength concrete and coated with a thermal insulation coating to ensure that heat loss is minimized during gas transportation.

[0051] Construction method: Mechanized construction is carried out using a tunnel boring machine (TBM), and the tunnel lining is made of materials with a compressive strength of not less than 50MPa.

[0052] Horizontal tunnel:

[0053] Function: It carries the functions of high temperature area, heat exchange area and cooling area, which are used for heat storage, transfer and cooling respectively.

[0054] Design parameters: The horizontal tunnel is located 2000m underground, with a total length of 10km and an inner diameter of 8m. The tunnel is clearly divided into different areas, and each area is isolated by high-performance insulation materials.

[0055] 1.2 High temperature area

[0056] Function: The high temperature zone is used to store the heat released by the compressed air and recover the heat during the expansion process to ensure that the temperature of the expanded air rises to 180.5°C and improve the expansion power generation efficiency.

[0057] Location: The high temperature zone is located near the heat storage end of the tunnel, accounting for 30% of the total length of the tunnel, and the area length is 3km.

[0058] Technical features:

[0059] Thermal storage material: Molten salt is used as a thermal storage medium with a specific heat capacity of 2.3 kJ / kg·K, which can efficiently absorb and store heat.

[0060] Thermal conductivity design: Thermal conductive materials (such as aluminum-based alloys) are embedded in the tunnel wall with a thermal conductivity of 205W / m·K to ensure that the heat of the air is quickly transferred to the heat storage body.

[0061] Temperature control: The temperature in the high temperature zone is maintained above 185°C, and a stable temperature is achieved through the efficient heat storage performance of the heat storage body.

[0062] 1.3 Heat exchange area

[0063] Function: The heat exchange area is used to regulate the temperature of compressed air and expanded air. It releases heat during compression and absorbs heat during expansion, playing a role in heat transition.

[0064] Location: The heat exchange zone is located between the high temperature zone and the cooling zone, accounting for 40% of the total length of the tunnel, with an area length of 4km.

[0065] Technical features:

[0066] Heat exchange device: Heat exchange tubes with enhanced inner surfaces (such as spiral fin tubes) are set inside the tunnel wall to improve the heat transfer efficiency between the air and the heat storage body.

[0067] Material selection: The heat exchange tube is made of high thermal conductivity aluminum alloy, and the inner wall is coated with corrosion-resistant coating to adapt to high temperature and high pressure environment.

[0068] Heat transfer path: Through convection and heat conduction, the compressed air heat is transferred to the heat storage body, and the expanded air absorbs heat from the heat storage body, and the temperature gradually changes.

[0069] 1.4 Cooling Zone

[0070] Function: The cooling zone is used to reduce the compressed air temperature to the target value (such as 35°C) to meet the requirements of the air storage room.

[0071] Location: The cooling zone is located near the cooling end of the tunnel, accounting for 30% of the total length of the tunnel, and the zone length is 3km.

[0072] Technical features:

[0073] Cooling device: A coolant circulation device is installed outside the tunnel wall. The coolant is circulating water, and the temperature is controlled at 15℃ to 20℃ through a cooling tower.

[0074] Heat management: When the compressed air passes through the cooling zone, the heat is absorbed by the coolant and the cooled air temperature is stabilized at 35°C.

[0075] Safety design: The coolant circulation system is equipped with a pressure regulating device to prevent gas expansion caused by excessive temperature difference during the cooling process.

[0076] 1.5 Gas pipeline

[0077] Function: It runs through high temperature area, heat exchange area and cooling area, and is used for the transportation of compressed air and expanded air.

[0078] Technical features:

[0079] Pipeline sharing design: It serves as the air inlet pipe during compression and as the air outlet pipe during expansion, saving pipeline resources.

[0080] Dynamic adjustment: The pipe diameter is dynamically adjusted according to pressure and temperature to ensure stable air flow rate and pressure.

[0081] Material selection: The pipeline is made of high-strength stainless steel with a temperature resistance range of -40℃ to 300℃, and the inner wall is coated with an anti-heat damage coating (such as ceramic composite coating).

[0082] 1.6 Multistage compression and expansion equipment

[0083] Function: Storage and expansion of compressed air to generate electricity.

[0084] Technical features:

[0085] Compression process:

[0086] First stage compression: the air temperature rises from 20°C to 204.5°C, passes through the cooling zone and is cooled to 35°C before entering the next compression stage;

[0087] Second to fourth stage compression: Repeat the first stage compression process, and finally the air enters the air storage chamber at high pressure and 35°C temperature.

[0088] Expansion process:

[0089] The air is discharged from the air storage chamber, passes through the high temperature zone and the heat exchange zone, and is heated to 180.5°C, and then enters the first-stage expander;

[0090] After four stages of expansion, the air pressure returns to ambient value and the temperature stabilizes at the initial level.

[0091] 2. System operation principle

[0092] 2.1 Energy storage process

[0093] The compressor compresses the air step by step, and the heat released by the air is absorbed by the heat storage body in the high temperature area and the heat exchange area in turn;

[0094] The compressed air is cooled to 35°C in the cooling zone and stored in the air storage room.

[0095] 2.2 Energy release process

[0096] The air is discharged from the air storage chamber, passes through the high temperature zone and the heat exchange zone to absorb heat and rise to 180.5°C, then enters the expander to expand step by step and generate electricity;

[0097] After expansion, the air passes through the cooling zone and is cooled to ambient temperature.

[0098] Embodiment 2:

[0099] This embodiment optimizes the tunnel layout under complex terrain conditions, adopts a combination of vertical shafts and curved tunnels to adapt to different terrain environments, and ensures that the function of the heat exchange system is not limited by geological conditions. At the same time, the heat transfer and storage efficiency is further improved by redistributing the functional areas.

[0100] 1. Tunnel structure design

[0101] 1.1 Shaft section

[0102] Length and diameter: The shaft is 2000m deep and has an inner diameter of 6m; the shaft connects ground equipment (such as compressors and expanders) with underground functional areas.

[0103] Construction method: Use shaft boring machine to complete the excavation, and lay high-strength concrete lining on the inner wall to ensure compressive performance.

[0104] Thermal insulation design: The inner wall is coated with composite ceramic thermal insulation material with a thermal conductivity of 0.02W / m·K to minimize the heat loss of compressed air.

[0105] Used for vertical transportation of compressed air;

[0106] The compressed air from the ground equipment is introduced directly into the functional area in the curved tunnel.

[0107] 1.2 Curved tunnel section

[0108] Length and layout: The total length of the curved tunnel is 8km, with a flexible layout design to adapt to complex terrain conditions; the radius of curvature is 500m and the inner diameter of the tunnel is 8m.

[0109] Inner wall material: A high thermal conductivity aluminum alloy plate is embedded in the tunnel wall, with a thermal conductivity of 205W / m·K; at the same time, a moisture-proof layer is added to avoid the influence of humidity in the deep underground environment.

[0110] The interior of the curved tunnel is divided into a high-temperature zone, a heat exchange zone and a cooling zone, and the zones are separated by thermal insulation layers.

[0111] The regional distribution is optimized according to the geometric characteristics of the curved tunnel, and each functional area is connected by a short straight tunnel to reduce air flow pressure loss.

[0112] 2. Functional area design

[0113] 2.1 High temperature area

[0114] Location and Distribution:

[0115] The high temperature zone is located at the end of the vertical shaft and the beginning of the curved tunnel, accounting for 40% of the total length of the curved tunnel, and the zone length is 3.2km.

[0116] The high temperature area is located close to the shaft outlet, so it can receive the heat of the compressed air and store it quickly.

[0117] Structural design:

[0118] The tunnel wall is embedded with metal matrix composite materials (such as copper-aluminum composite panels) with a thermal conductivity of 150W / m·K and a high temperature resistance range of 0°C to 400°C.

[0119] It adopts a thermal storage modular design, with each module measuring 10m×8m×3m and can operate independently or be used in parallel.

[0120] Heat storage and transfer:

[0121] The heat storage material is a metal oxide (such as magnesium oxide), which has a specific heat capacity of 1.02 kJ / kg·K and a thermal conductivity of 30 W / m·K.

[0122] When compressed air passes through the high-temperature zone, it releases heat to the metal oxide thermal storage body, and the thermal storage material stores the heat in a highly efficient conduction manner.

[0123] Temperature Control:

[0124] The temperature in the high temperature zone is maintained above 185°C;

[0125] The thermal management system monitors the temperature of the thermal storage material in real time and adjusts the air flow rate to keep the temperature stable.

[0126] 2.2 Heat exchange area

[0127] Location and Distribution:

[0128] The heat exchange area is located between the high temperature area and the cooling area, accounting for 30% of the total length of the curved tunnel, and the area length is 2.4km.

[0129] Structural design:

[0130] The heat exchange device is installed in the tunnel wall and adopts a spiral fin tube design with a reinforced inner surface to improve the heat exchange efficiency between the air and the heat exchange tube.

[0131] The heat exchange tube is made of high thermal conductivity aluminum alloy, with a wall thickness of 5mm, and can withstand high temperatures of 200°C and pressures of 20MPa.

[0132] Temperature Regulation:

[0133] Compression process: When air passes through the heat exchange zone, the heat is released to the heat storage body step by step, and the temperature gradually decreases from 204.5℃ to 100℃;

[0134] Expansion process: When air passes through the heat exchange area, it absorbs heat from the heat storage body and the temperature gradually rises from 35℃ to 120℃.

[0135] 2.3 Cooling Zone

[0136] Location and Distribution:

[0137] The cooling zone is located at the end of the curved tunnel, accounting for 30% of the total length of the curved tunnel, and the zone length is 2.4 km.

[0138] Cooling device design:

[0139] The coolant is ethylene glycol water solution with a concentration of 40% and an operating temperature range of -20°C to 40°C;

[0140] The coolant exchanges heat with the air through a heat exchanger, and a turbulence device is added inside the heat exchanger to improve the heat transfer efficiency.

[0141] Air cooling process:

[0142] When the compressed air passes through the cooling zone, the heat is absorbed by the ethylene glycol aqueous solution, and the air temperature drops from 100°C to 35°C;

[0143] The coolant is circulated through the cooling tower for cooling, and the heat is discharged to the environment through the cooling tower.

[0144] 3. Gas pipeline design

[0145] Dynamic adjustment function:

[0146] The gas pipeline runs through vertical shafts and curved tunnels, with an inner diameter designed to be 1.2m to 1.8m. The specific diameter is dynamically adjusted according to air pressure and temperature.

[0147] Anti-heat loss design:

[0148] The inner wall of the pipeline is coated with a heat-loss-proof ceramic coating with a thermal conductivity of 0.03W / m·K, ensuring that the air heat loss is less than 1%.

[0149] Pipeline layout:

[0150] The outer wall of the pipe is tightly combined with the tunnel wall, and the interface thermal resistance is reduced by heat-conducting contact materials (such as silicone gaskets).

[0151] 4. System operation principle

[0152] 4.1 Energy storage process

[0153] After being compressed from the surface equipment, the air is transported to the high temperature area through the shaft;

[0154] The high temperature zone absorbs the heat released by the compressed air and stores it in the metal oxide thermal storage body;

[0155] The compressed air releases excess heat through the heat exchange area and finally enters the air storage chamber after being cooled to 35°C in the cooling area.

[0156] 4.2 Energy release process

[0157] The air is discharged from the air storage chamber, passes through the heat exchange area and the high temperature area to absorb heat, and the temperature rises to 180.5℃;

[0158] The air enters the expander and expands step by step. After completing work and power generation, it is cooled to ambient temperature through the cooling zone.

[0159] Embodiment three:

[0160] This embodiment uses metal oxide as the thermal storage material and ethylene glycol aqueous solution or liquid nitrogen as the cooling medium to meet the energy storage needs in special environments, such as extremely high temperature, high pressure or low temperature environments. At the same time, through the optimization design of materials and media, the thermal efficiency and stability of the system operation are further improved.

[0161] 1. Tunnel structure design

[0162] 1.1 Tunnel infrastructure

[0163] Tunnel layout:

[0164] This embodiment still adopts the combined layout of inclined shaft and horizontal tunnel.

[0165] Inclined shaft: 7km in length, 15° inclination, 7m in inner diameter, and the inner wall is coated with a high heat-resistant protective coating (such as a ceramic coating).

[0166] Horizontal tunnel: located 1800m underground, with a length of 9km and an inner diameter of 8m. The interior is divided into high-temperature zone, heat exchange zone and cooling zone.

[0167] Thermal insulation and thermal conductivity design:

[0168] High-performance insulation panels (thermal conductivity less than 0.05W / m·K) are used to isolate tunnel partitions to avoid ineffective heat diffusion between areas.

[0169] High thermal conductivity materials (such as copper-aluminum composite panels) are embedded in the tunnel walls to improve heat transfer efficiency in high-temperature and heat exchange areas.

[0170] 2. Functional area design

[0171] 2.1 High temperature area

[0172] Location and Distribution:

[0173] The high temperature zone is located near the heat storage end of the tunnel, accounting for 35% of the total length of the tunnel, and the length of the zone is 3.15km.

[0174] Thermal storage material selection:

[0175] In this embodiment, metal oxide is used as the heat storage material in the high temperature zone.

[0176] Material properties:

[0177] Specific heat capacity: 1.02 kJ / kg·K;

[0178] Thermal conductivity: 30W / m·K;

[0179] Operating temperature range: 0℃ to 500℃;

[0180] Excellent corrosion resistance, suitable for high temperature and high pressure environment.

[0181] Material application: Metal oxides are embedded in the tunnel wall in a modular form. The size of a single module is 10m×8m×3m and it can operate independently.

[0182] Temperature control and transmission:

[0183] The heat storage material absorbs the heat released by the compressed air and maintains the temperature above 185°C.

[0184] During the expansion process, the heat storage material efficiently transfers heat to the expanding air, ensuring that the air temperature reaches 180.5°C before entering the expander.

[0185] 2.2 Heat exchange area

[0186] Location and Distribution:

[0187] The heat exchange zone is located between the high temperature zone and the cooling zone, accounting for 30% of the total length of the tunnel, with an area length of 2.7 km.

[0188] Heat exchange device:

[0189] The heat exchange device is a finned tube with enhanced inner surface:

[0190] Material: high thermal conductivity aluminum-based alloy;

[0191] Tube wall thickness: 6mm, internal strengthening fin spacing is 2mm;

[0192] Pressure range: 20MPa;

[0193] Thermal conductivity: 205W / m·K.

[0194] A turbulence promoting structure (such as a spiral flow channel) is added inside to further improve the heat transfer efficiency between the air and the heat exchange tube.

[0195] Heat Regulation:

[0196] Compression process: The heat released by the compressed air is gradually transferred to the high temperature area, and the air temperature drops from 204.5℃ to 100℃;

[0197] Expansion process: The expanding air absorbs heat from the high temperature area and the heat exchange area, and the temperature gradually rises from 35°C to 120°C.

[0198] 2.3 Cooling Zone

[0199] Location and Distribution:

[0200] The cooling zone is located at the end of the tunnel, accounting for 35% of the total tunnel length, with a zone length of 3.15km.

[0201] Cooling medium selection:

[0202] This embodiment uses ethylene glycol aqueous solution or liquid nitrogen as the cooling medium:

[0203] Ethylene glycol aqueous solution:

[0204] Concentration: 40%;

[0205] Specific heat capacity: 2.5 kJ / kg·K;

[0206] Operating temperature range: -20℃ to 40℃;

[0207] Used for cooling needs in normal temperature environment.

[0208] Liquid Nitrogen:

[0209] Specific heat capacity: 2.04 kJ / kg·K;

[0210] Operating temperature range: -196°C to 20°C;

[0211] Used for cooling needs in extremely low temperature environments.

[0212] Cooling device design:

[0213] The coolant circulates through the pipeline to exchange heat with the compressed air, and the heat is quickly absorbed by the ethylene glycol aqueous solution or liquid nitrogen.

[0214] The heat exchanger adopts a modular design, with each module measuring 8m×6m×3m, and can be combined according to actual needs.

[0215] Air cooling process:

[0216] After the compressed air passes through the cooling zone, the temperature drops from 100°C to 35°C;

[0217] The coolant is cooled again through a cooling tower or circulation system to ensure a continuous and stable cooling effect.

[0218] 3. Gas pipeline design

[0219] Pipe material and diameter:

[0220] The pipe material is high-strength aluminum-based alloy with a temperature resistance range of -50°C to 300°C and excellent corrosion resistance and pressure resistance;

[0221] The inner diameter is designed to be 1.5m, and the diameter is dynamically adjusted according to air flow rate, pressure and temperature.

[0222] Heat loss prevention and thermal conductivity design:

[0223] The inner wall of the pipeline is coated with a high temperature resistant and heat loss resistant coating (ceramic composite coating), with a coating thickness of 0.5 mm and a thermal conductivity of 0.03 W / m·K;

[0224] Thermally conductive silicone gaskets are filled between the outer wall and the tunnel wall to reduce thermal resistance.

[0225] Dedicated pipes for cooling area:

[0226] The cooling zone pipeline is equipped with a low-temperature protective coating, which is particularly suitable for the working environment of liquid nitrogen.

[0227] 4. System operation principle

[0228] 4.1 Energy storage process

[0229] The air is compressed step by step through the compressor, and the released heat is absorbed by the metal oxide heat storage materials in the high temperature area and the heat exchange area respectively.

[0230] The compressed air is cooled to 35°C in the cooling zone and then stored in the air storage room.

[0231] 4.2 Energy release process

[0232] The air is discharged from the air storage chamber, passes through the heat exchange area and the high temperature area to absorb heat, and the temperature rises to 180.5℃;

[0233] The air expands through four-stage expanders in sequence and produces work to generate electricity;

[0234] The expanded air is cooled to ambient temperature through the cooling zone.

[0235] 5. Implementation Effect

[0236] Improved heat storage capacity:

[0237] Using metal oxides as thermal storage materials, the heat capacity is increased by about 20% compared to traditional molten salts, making it suitable for higher temperature operating requirements.

[0238] Enhanced Cooling Efficiency:

[0239] The ethylene glycol aqueous solution achieves efficient heat absorption at room temperature, and the liquid nitrogen operates stably in an extremely low temperature environment, which expands the application scope of the system.

[0240] Improved energy efficiency:

[0241] The heat transfer efficiency is increased by 10%-15%, and the overall energy utilization rate of the system reaches more than 85%.

[0242] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A heat exchange system based on constant pressure compressed air energy storage, characterized in that: include: Tunnel structure, consisting of inclined shafts and horizontal tunnels; Inclined shaft: connected to the ground equipment and used for the transportation of compressed air; Horizontal tunnel: set deep underground, divided into high temperature area, heat exchange area and cooling area; High temperature zone: located at one end of the horizontal tunnel, used to store the heat of compressed air, with the temperature maintained at no less than 185°C; Heat exchange area: located between the high temperature area and the cooling area, used for heat transfer and temperature regulation of compressed air and expanded air; Cooling zone: located at the other end of the horizontal tunnel, used to cool the compressed air to the target temperature; Gas transmission pipeline: runs through the high-temperature area, heat exchange area and cooling area, serving as the air inlet pipeline during compression and as the air outlet pipeline during expansion; Multi-stage compression and expansion equipment is connected to the high temperature area, heat exchange area and cooling area through pipelines, and is used for storage and expansion of compressed air to generate electricity.

2. A heat exchange system based on constant pressure compressed air energy storage according to claim 1, characterized in that: The high temperature zone includes: Thermal storage materials set in the tunnel wall to store and release heat; The heat storage material is molten salt or high specific heat capacity metal.

3. A heat exchange system based on constant pressure compressed air energy storage according to claim 1, characterized in that: The heat exchange zone comprises: A heat exchange device is arranged in the tunnel wall, wherein the heat exchange device is a heat exchange tube with a reinforced inner surface; The heat exchange tube adjusts the temperature of the compressed air or the expanded air by convection and heat conduction.

4. A heat exchange system based on constant pressure compressed air energy storage according to claim 1, characterized in that: The cooling zone comprises: A coolant circulation device arranged outside the tunnel wall is used to absorb the heat of the compressed air through the cooling medium; The coolant is circulating water or industrial coolant.

5. A heat exchange system based on constant pressure compressed air energy storage according to claim 1, characterized in that: The multi-stage compression and expansion device comprises: At least four-stage compressor, used to compress the air to a high pressure state step by step; At least four stages of expanders are used to expand the air step by step and restore it to ambient pressure.

6. A heat exchange system based on constant pressure compressed air energy storage according to claim 1, characterized in that: The inner wall of the gas transmission pipeline is coated with a heat-damage-resistant coating, and the pipeline diameter is dynamically adjusted according to pressure and temperature.

7. A heat exchange system based on constant pressure compressed air energy storage according to claim 1, characterized in that: The design parameters of the inclined well include: The length of the inclined shaft is 6km to 10km; The inclination of the inclined well is 10° to 20°; The inner diameter is 6m to 10m.

8. A heat exchange system based on constant pressure compressed air energy storage according to claim 1, characterized in that: The layout of the horizontal tunnel can be adjusted to a vertical shaft or a curved tunnel.

9. A heat exchange system based on constant pressure compressed air energy storage according to claim 1, characterized in that: The length of the heat exchange zone is dynamically adjusted according to the power demand of the compressed air, and its length ranges from 20% to 60% of the total length of the tunnel.

10. A heat exchange system based on constant pressure compressed air energy storage according to claim 1, characterized in that: The heat storage material can be selected as metal oxide, and the cooling medium can be selected as ethylene glycol aqueous solution or liquid nitrogen.

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