Combined heat exchanger and compressed air energy storage system

Abstract

The invention discloses a combined heat exchanger and a compressed air energy storage system, and relates to the technical field of heat exchangers. The combined heat exchanger comprises a shell. A high-temperature area is arranged in the shell, the shell comprises an upper tube plate and a lower tube plate, the tube winding bundle is arranged between the upper tube plate and the lower tube plate, the upper end of the tube winding bundle is connected to a tube plate hole of the upper tube plate in an expanded mode, and the lower end of the tube winding bundle is connected to a tube plate hole of the lower tube plate in an expanded mode. A low-temperature area is further arranged in the shell and located below the lower tube plate, and a heat exchange core with the heat transfer efficiency higher than that of the wound tube bundle under the low-temperature working condition is arranged in the low-temperature area. The combined heat exchanger solves the technical problems that in the prior art, a high-temperature-resistant and high-pressure-resistant heat exchanger is high in price, and the heat exchange efficiency does not have obvious advantages under the low-temperature working condition.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and more particularly to a combined heat exchanger and a compressed air energy storage system. Background Technology

[0002] The energy storage industry has a large demand for heat exchangers, requiring them to operate at temperatures above 200℃ and pressures above 10MPa. With the development of energy storage technology, a large number of heat exchangers are needed within energy storage systems.

[0003] In the process of developing this invention, the inventors discovered at least the following problems in the prior art: heat exchangers resistant to high temperatures and high pressures are expensive, and their heat exchange efficiency does not have a significant advantage under low-temperature conditions. Reducing the amount of heat exchangers resistant to high temperatures and high pressures and replacing them with low-temperature, high-pressure heat exchangers can reduce equipment costs, but the large footprint of the entire heat exchange assembly increases the equipment's floor space cost.

[0004] Taking compressed air energy storage as an example, the system has a large number of heat exchange requirements under high temperature and high pressure conditions, and the balance between the performance and cost of the heat exchanger is crucial. Summary of the Invention

[0005] The purpose of this invention is to provide a lower-cost combined heat exchanger.

[0006] To achieve this objective, on the one hand, a combined heat exchanger is provided, including a shell; the shell includes a high-temperature zone, the shell includes an upper tube sheet and a lower tube sheet, a coiled tube bundle is disposed between the upper tube sheet and the lower tube sheet, the upper end of the coiled tube bundle is expanded to a tube sheet hole of the upper tube sheet, and the lower end of the coiled tube bundle is expanded to a tube sheet hole of the lower tube sheet; the shell also includes a low-temperature zone, the low-temperature zone is located below the lower tube sheet, and the low-temperature zone is provided with a heat exchange core that has a higher heat transfer efficiency than the coiled tube bundle under low-temperature conditions.

[0007] Furthermore, the heat exchange core in the low-temperature zone is a plate-fin heat exchange core, with the first and second channels of the plate-fin heat exchange core arranged perpendicularly, and the second channel of the plate-fin heat exchange core connected to the lower end of the tube bundle.

[0008] Furthermore, the shell has a water inlet pipe, which is connected to one end of the first channel of the plate-fin heat exchanger core. The other end of the first channel of the plate-fin heat exchanger core is connected to one end of the connecting pipe, and the other end of the connecting pipe is connected to the shell side of the high-temperature zone. A water outlet pipe is provided at the other end of the shell in the high-temperature zone opposite to the connecting pipe.

[0009] Furthermore, the plate-fin heat exchange core is fixed to the inner wall of the shell by a support frame, and the middle of the support frame has a through hole that matches the size of the shell-side heat exchange area of ​​the plate-fin heat exchange core.

[0010] Furthermore, fixed wings are provided on the outer periphery of the plate-fin heat exchange core, and grooves matching the shape of the fixed wings are provided on the upper surface of the support frame. When the plate-fin heat exchange core is assembled with the support frame, the fixed wings are snapped together and fixedly connected in the grooves.

[0011] Furthermore, a partition and a flexible pad are provided in the groove. The flexible pad is sandwiched between the partition and the groove. The partition is welded to the upper surface of the support frame at the groove opening. The fixed wing of the plate-fin heat exchange core is engaged in the partition. The flexible pad absorbs the stress generated by the plate-fin heat exchange core during operation.

[0012] Furthermore, the bottom of the support frame is provided with multiple support legs, which are evenly distributed at the bottom of the support frame. One end of each support leg is fixedly connected to the bottom of the support frame, and the other end of the support leg is fixedly connected to the inner wall of the shell of the low-temperature zone.

[0013] Furthermore, the gas passage at the upper end cap is connected to the tube side of the coiled tube bundle; the gas passage at the lower end cap is connected to the second channel of the plate-fin heat exchanger core, and the coiled tube bundle is connected to the second channel of the plate-fin heat exchanger core at the lower tube sheet.

[0014] Furthermore, it also includes a drain pipe section, one end of which is connected to the lower tube sheet, and the other end of which is connected to the shell.

[0015] On the other hand, a compressed air energy storage system is also provided, including the aforementioned combined heat exchanger, wherein the combined heat exchanger is disposed at the outlet of the compressor, or the combined heat exchanger is disposed at the inlet of the expander.

[0016] One of the above technical solutions has the following advantages or beneficial effects: The combined heat exchanger of this solution includes a high-temperature zone and a low-temperature zone. The high-temperature zone uses a wound tube heat exchanger structure with high heat transfer efficiency under high-temperature conditions, and the low-temperature zone uses a heat exchange core with high heat transfer efficiency under low-temperature conditions. In this field, heat exchange cores with high heat transfer efficiency under low-temperature conditions also have the advantage of low cost. Therefore, the combined heat exchanger of this embodiment balances the performance and cost of the heat exchanger, and has the advantage of lower cost under the same heat transfer efficiency. Attached Figure Description

[0017] Figure 1 This is an external view of the combined heat exchanger in this embodiment; Figure 2 This is a schematic diagram of the internal structure of the combined heat exchanger in this embodiment; Figure 3 This is a schematic diagram of the structure of the plate-fin heat exchanger core in the low-temperature zone; Figure 4 This is a structural schematic diagram of the support frame for the heat exchanger core in the low-temperature zone at one angle. Figure 5This is a structural schematic diagram of the support frame for the heat exchanger core in the low-temperature zone from another angle. Figure 6 This is a schematic diagram of the assembly structure of the partition and flexible pad at the groove of the support frame.

[0018] In the diagram: 100-Shell; 101-Cylindrical barrel; 102-Upper head; 103-Lower head; 104-Upper flange; 105-Lower flange; 110-Inlet pipe; 120-Connecting pipe; 130-Outlet pipe; 131-Upper tube sheet; 132-Lower tube sheet; 200-High temperature zone; 210-Wrapped tube bundle; 220-Central cylinder; 300-Low temperature zone; 310-Plate-fin heat exchanger core; 311-Fixed wing; 312-Left tube box; 320-Support frame; 321-Support leg; 322-Groove; 323-Baffle plate; 324-Flexible pad; 325-Through hole; 400-Drainage pipe section. Detailed Implementation

[0019] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0020] This embodiment provides a combined heat exchanger that can be used under high-pressure conditions in compressed air energy storage systems. For example... Figure 1 As shown, the combined heat exchanger includes a shell 100, the main body of which is a cylindrical barrel 101. To reduce the floor space occupied by the entire heat exchanger, the generatrix of the main body of the shell 100 is set perpendicular to the ground. The upper part of the cylindrical barrel 101 has a hemispherical upper end cap 102, and the lower part of the cylindrical barrel 101 has a hemispherical lower end cap 103.

[0021] The shell 100 of the combined heat exchanger is divided into a high-temperature zone 200 and a low-temperature zone 300, which are separated by tube sheets. The shell 100 includes an upper tube sheet 131 and a lower tube sheet 132. The high-temperature zone 200 is located between the upper tube sheet 131 and the lower tube sheet 132, and the low-temperature zone 300 is located between the lower tube sheet 132 and the lower end cap 103. The high-temperature zone 200 has a heat exchange structure with high heat exchange efficiency under high-temperature and high-pressure conditions, and the low-temperature zone 300 has a heat exchange structure with high heat exchange efficiency under low-temperature and high-pressure conditions.

[0022] Furthermore, in this embodiment, the heat exchange structure of the high-temperature zone 200 within the shell 100 of the combined heat exchanger is a wound-tube heat exchange structure. The wound-tube heat exchange structure includes a central cylinder 220 for supporting the wound tube bundles 210. The wound tube bundles 210 include multiple wound tubes, all of which are spirally wound around the outside of the central cylinder 220, with the wound tube bundles 210 stacked and wound together. To facilitate illustrating the assembly relationship between the wound tubes and the central cylinder 220, only one wound tube is shown in the figure.

[0023] The upper tube sheet 131 is provided with a tube sheet hole for expansion connection with one end of each winding tube, and the lower tube sheet 132 is provided with a tube sheet hole for expansion connection with the other end of each winding tube. The two ends of the winding tube bundle 210 are respectively expanded and connected to the upper tube sheet 131 and the lower tube sheet 132, so as to achieve sealing and fixation between the winding tube bundle 210 and the upper tube sheet 131 and the lower tube sheet 132.

[0024] Optionally, the two layers of winding tubes are not connected, and the tube bundle is bent and wound around the central cylinder 220, so that the tube bundle has a certain stress absorption effect. The spiral directions of adjacent two layers of winding tubes are opposite, and the inner and outer layers of winding tubes are arranged alternately with left-hand and right-hand spirals, and the gaps between the layers are maintained by stainless steel spacers or corrugated spacers.

[0025] While wound-tube heat exchange structures can maintain stable and efficient heat exchange performance under high-temperature and high-pressure conditions, their efficiency improvement is limited under low-temperature and high-pressure conditions, and they also suffer from large size and high cost. In this embodiment, the low-temperature zone 300 within the shell 100 of the combined heat exchanger is a plate-fin heat exchange core 310 structure.

[0026] Under low-temperature and low-pressure conditions, compared with wound-tube heat exchangers, the plate-fin heat exchanger core 310 structure has the following advantages: First, it has high heat transfer efficiency. The aluminum plate-fin heat exchanger, through its dense fin structure, significantly increases the heat transfer area. The fluid forms strong turbulence within the narrow channels, significantly improving the convective heat transfer coefficient, resulting in an overall heat transfer efficiency far exceeding that of wound-tube heat exchangers. Second, it has a more compact structure. The heat transfer area per unit volume of the aluminum plate-fin heat exchanger is greater than 1000 m² / m³, far exceeding that of wound-tube heat exchangers. Therefore, for the same heat transfer capacity, its volume is smaller, offering significant space-saving advantages. Finally, it is lightweight. The aluminum plate-fin heat exchanger uses aluminum alloy material, which has a low density. For the same heat transfer area, its weight is only about 1 / 3 of that of a wound-tube heat exchanger, significantly reducing transportation and installation costs.

[0027] Optionally, the plate-fin heat exchanger core 310 has two vertically arranged, mutually isolated channels. For example... Figure 1The plate-fin heat exchanger core 310 has two mutually isolated channels, a first channel and a second channel, which are arranged perpendicularly to each other. Further, the horizontal channel is the first channel, and the vertical channel is the second channel. Tube boxes are provided at both ends of the first channel. In this embodiment, the inlet pipe 110 of the combined heat exchanger is connected to the inlet of the first channel of the plate-fin heat exchanger core 310. The fluid in the first channel passes through the left tube box, is distributed to each heat exchange unit of the first channel via the left tube box 312, and then enters the right tube box. After converging in the right tube box, it enters the pipeline.

[0028] Furthermore, in the low-temperature zone 300, the plate-fin heat exchange core 310 is supported and fixed to the inner wall of the shell 100 by a support frame 320. The support frame 320 has a through hole 325 in the middle that matches the heat exchange area of ​​the second channel of the plate-fin heat exchange core 310.

[0029] Furthermore, the bottom of the support frame 320 is provided with a plurality of support legs 321, which are evenly arranged at the bottom of the support frame 320. One end of each support leg 321 is fixedly connected to the bottom of the support frame 320, and the other end of the support leg 321 is fixedly connected to the inner wall of the shell 100 of the low temperature zone 300.

[0030] Furthermore, the outer periphery of the plate-fin heat exchange core 310 is provided with fixed wings 311, and the upper surface of the support frame 320 is provided with grooves 322 that match the shape of the fixed wings 311. When the plate-fin heat exchange core 310 and the support frame 320 are assembled, the fixed wings 311 on it are engaged in the grooves 322.

[0031] Optionally, a partition and a flexible pad 324 are provided within the groove 322, with the flexible pad 324 sandwiched between the partition and the groove 322. The partition and the support frame 320 are welded at the opening of the groove 322. The fixed wing 311 of the plate-fin heat exchange core 310 is engaged within the partition and welded to it. Optionally, the flexible pad 324 can be made of rubber. By providing the flexible pad 324 between the plate-fin heat exchange core 310 and the support frame 320, the plate-fin heat exchange core 310 has a certain degree of freedom in the direction perpendicular to the plate surface, which can absorb the stress generated by the plate-fin heat exchange core 310 during operation.

[0032] Furthermore, the plate-fin heat exchange core 310 is rectangular, and a fixed wing 311 is provided on each of the four sides of the rectangular plate-fin heat exchange core 310. Correspondingly, the upper surface of the support frame 320 is provided with four grooves 322 that match the shape of the fixed wing 311.

[0033] The working process of the combined heat exchanger is explained using the combined heat exchanger of this embodiment for gas and liquid heat exchange as an example.

[0034] In this embodiment, the inlet pipe 110 of the combined heat exchanger is connected to the inlet of the first channel of the plate-fin heat exchange core 310, and the wall of the inlet pipe 110 is sealed to the shell 100. The outlet of the first channel of the plate-fin heat exchange core 310 is connected to the connecting pipe 120, and the other end of the connecting pipe 120 extends into the inner wall of the shell 100 in the high-temperature zone 200. The outlet pipe 130 of the combined heat exchanger is also located on the shell 100 in the high-temperature zone 200. The wall of one end of the connecting pipe 120 is sealed to the shell 100 in the low-temperature zone 300. The other end of the connecting pipe 120 is fixed to the shell 100 in the high-temperature zone 200, and the outlet pipe 130 is fixed to the shell 100 in the high-temperature zone 200.

[0035] Furthermore, a flow meter for monitoring the inlet flow of the combined heat exchanger is installed on the outlet pipe 130.

[0036] Optionally, the other end of the connecting pipe 120 is arranged opposite to the outlet pipe 130 on the housing 100, and the other end of the connecting pipe 120 is positioned above the outlet pipe 130.

[0037] Optionally, the shell 100 of the combined heat exchanger has a drain pipe section 400 for discharging liquid from the shell side of the high-temperature zone 200. Optionally, the drain pipe section is L-shaped, with one end connected to the lower tube sheet 132 and the other end extending out of the shell 100 from the low-temperature zone 300. A sealing structure for sealing the drain pipe section is provided between the drain pipe section and the shell 100.

[0038] The gas passage of the combined heat exchanger is located at both ends on the upper head 102 and the lower head 103, respectively. The gas passage of the upper head 102 is equipped with an upper flange 104 and is connected to the tube side of the coiled tube bundle 210. The gas passage of the lower head 103 is equipped with a lower flange 105 and is connected to the second passage of the plate-fin heat exchange core 310. The coiled tube bundle 210 and the second passage of the plate-fin heat exchange core 310 are connected at the lower tube sheet 132.

[0039] When the water circuit of the combined heat exchanger exchanges heat with the high-temperature gas, the high-temperature gas enters the coiled tube bundle 210 from the upper flange 104, flows out of the coiled tube bundle 210, and enters the second channel of the plate-fin heat exchange core 310. The low-temperature liquid enters from the inlet pipe 110 and flows into the second channel of the plate-fin heat exchange core 310. After the initial heat exchange with the gas in the first channel of the plate-fin heat exchange core 310, the liquid flows out of the second channel of the plate-fin heat exchange core 310 and enters the shell side of the high-temperature zone 200 through the connecting pipe 120, where it exchanges heat again with the high-temperature gas inside the coiled tube bundle 210.

[0040] The cryogenic fluid flows from the inlet pipe 110 into the second channel of the plate-fin heat exchanger core 310 in the cryogenic zone 300. After exchanging heat with the gas in the first channel of the plate-fin heat exchanger core 310, the cryogenic fluid becomes a medium-temperature fluid. The medium-temperature fluid then enters the shell side of the high-temperature zone 200 through the connecting pipe 120, where it exchanges heat with the high-temperature gas in the tube bundle 210 of the high-temperature zone 200 and becomes a high-temperature fluid, which flows out from the outlet pipe 130. In the above process, the high-temperature gas entering from the upper flange 104 becomes cryogenic gas and flows out from the lower flange 105.

[0041] When the water circuit of the combined heat exchanger exchanges heat with the low-temperature gas, the low-temperature gas enters from the lower flange 105, first passes through the first channel of the plate-fin heat exchanger core 310 in the low-temperature zone 300, and then flows out through the first channel of the low-temperature zone 300 before entering the high-temperature zone 200 through the tube sheet holes on the lower tube sheet 132. Simultaneously, high-temperature water enters from the inlet pipe 110 and flows into the second channel of the plate-fin heat exchanger core 310. After initial heat exchange with the low-temperature gas in the first channel of the plate-fin heat exchanger core 310, the high-temperature water becomes medium-temperature water and enters the shell side of the high-temperature zone 200 through the connecting pipe 120. The heated gas flowing out from the first channel of the low-temperature zone 300 enters the tube bundle 210 through the tube sheet holes on the lower tube sheet 132, exchanging heat with the medium-temperature water in the shell side of the high-temperature zone 200. The high-temperature gas flows out from the upper flange 104, and the low-temperature water flows out from the outlet pipe 130.

[0042] In this embodiment of the combined heat exchanger, the high-temperature zone 200 uses a wound-tube heat exchange structure, while the low-temperature zone 300 uses a plate-fin heat exchange core 310. However, under low-temperature and high-pressure conditions, the heat exchange efficiency of the wound-tube heat exchange structure is lower than that of the plate-fin heat exchange core 310. Furthermore, under these conditions, the volume of the wound-tube heat exchange structure is larger than that of the plate-fin heat exchange core 310. Therefore, the aluminum-fin plate heat exchange core structure exhibits advantages at the low-temperature and high-pressure end, possessing excellent low-temperature heat exchange performance and compactness, which can improve heat exchange efficiency and reduce material costs.

[0043] Furthermore, the plate-fin heat exchanger core 310 uses an aluminum fin plate heat exchanger core structure, which is more economical.

[0044] The combined heat exchanger of this embodiment can be used in a compressed air energy storage system. In energy storage operation, the combined heat exchanger is located at the compressor outlet. The high-temperature gas from the compressor outlet is connected to the upper flange 104 of the combined heat exchanger via a pipeline. The high-temperature compressed gas enters the high-temperature zone 200 of the combined heat exchanger, passes through the coiled tube bundle 210, and enters the second channel of the plate-fin heat exchange core 310, becoming low-temperature compressed air that flows out from the lower flange 105. Low-temperature water enters the combined heat exchanger through the inlet pipe 110, exchanges heat with the gas path, and becomes high-temperature water that flows out from the outlet pipe 130. Low-temperature compressed air flows out from the lower flange 105, which is connected to the inlet of the next stage compressor or to the inlet of the gas storage tank.

[0045] In the energy storage and release operation, the combined heat exchanger is equipped with an expander inlet. Low-temperature compressed air flowing from the gas storage tank enters the combined heat exchanger through the lower flange 105. The low-temperature compressed air first enters the second channel of the plate-fin heat exchanger core 310, and after flowing out from the second channel, it enters the coiled tube bundle 210 through holes in the tube sheet, and then flows out from the upper flange 104 via the coiled tube bundle 210. High-temperature water flows in from the inlet, first passes through the first channel of the plate-fin heat exchanger core, and then enters the tube side of the high-temperature zone through the connecting pipe. After exchanging heat with the low-temperature compressed air in the coiled tube bundle, it becomes low-temperature water and flows out from the outlet pipe. The high-temperature compressed air flowing out from the upper flange 104 enters the expander inlet for expansion and power generation.

[0046] Therefore, the combined heat exchanger in this embodiment combines a high-temperature, high-pressure end coiled tube structure with a low-temperature, high-pressure end aluminum finned plate structure, integrating them into a single cylindrical heat exchange structure. When used in a compressed air energy storage system, it meets the heat exchange requirements of the compressed air energy storage system while reducing the system's footprint. Therefore, the compressed air energy storage system of this embodiment has the advantage of lower cost while ensuring performance.

[0047] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0048] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0049] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A combined heat exchanger, characterized in that, Includes the casing; The shell includes a high-temperature zone and includes an upper tube sheet and a lower tube sheet. A tube bundle is disposed between the upper tube sheet and the lower tube sheet. The upper end of the tube bundle is expanded into a tube sheet hole of the upper tube sheet, and the lower end of the tube bundle is expanded into a tube sheet hole of the lower tube sheet. The shell also includes a low-temperature zone, which is located below the lower tube sheet. The low-temperature zone contains a heat exchange core with a higher heat transfer efficiency than the wound tube bundle under low-temperature conditions.

2. The combined heat exchanger according to claim 1, characterized in that, The heat exchange core in the low-temperature zone is a plate-fin heat exchange core. The first and second channels of the plate-fin heat exchange core are arranged perpendicularly, and the second channel of the plate-fin heat exchange core is connected to the lower end of the tube bundle.

3. The combined heat exchanger according to claim 2, characterized in that, The shell has an inlet pipe that is connected to one end of the first channel of the plate-fin heat exchanger core. The other end of the first channel of the plate-fin heat exchanger core is connected to one end of a connecting pipe. The other end of the connecting pipe is connected to the shell side of the high-temperature zone. An outlet pipe is provided at the other end of the shell in the high-temperature zone opposite to the connecting pipe.

4. The combined heat exchanger according to claim 1, characterized in that, The plate-fin heat exchanger core is fixed to the inner wall of the shell by a support frame, and the middle of the support frame has a through hole that matches the size of the shell-side heat exchange area of ​​the plate-fin heat exchanger core.

5. The combined heat exchanger according to claim 4, characterized in that, Fixed wings are provided on the outer periphery of the plate-fin heat exchange core. The upper surface of the support frame is provided with grooves that match the shape of the fixed wings. When the plate-fin heat exchange core is assembled with the support frame, the fixed wings are snapped together and fixedly connected in the grooves.

6. The combined heat exchanger according to claim 5, characterized in that, A partition and a flexible pad are provided in the groove. The flexible pad is sandwiched between the partition and the groove. The partition is welded to the upper surface of the support frame at the groove opening. The fixed wing of the plate fin heat exchanger core is engaged in the partition. The flexible pad absorbs the stress generated by the plate fin heat exchanger core during operation.

7. The combined heat exchanger according to claim 3, characterized in that, The bottom of the support frame is provided with multiple support legs, which are evenly distributed at the bottom of the support frame. One end of each support leg is fixedly connected to the bottom of the support frame, and the other end of the support leg is fixedly connected to the inner wall of the shell of the low temperature zone.

8. The combined heat exchanger according to claim 2, characterized in that, The gas passage at the upper end cap is connected to the tube side of the coiled tube bundle; the gas passage at the lower end cap is connected to the second channel of the plate-fin heat exchanger core, and the coiled tube bundle is connected to the second channel of the plate-fin heat exchanger core at the lower tube sheet.

9. The combined heat exchanger according to claim 1, characterized in that, It also includes a drain pipe section, one end of which is connected to the lower tube sheet, and the other end of which is connected to the shell.

10. A compressed air energy storage system, characterized in that, Includes the combined heat exchanger as described in any one of claims 1-9, wherein the combined heat exchanger is disposed at the outlet of the compressor, or wherein the combined heat exchanger is disposed at the inlet of the expander.

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