Spiral wound heat exchanger and refrigeration system

Abstract

The present application relates to the technical field of refrigeration, in particular to a coiled tube heat exchanger and a refrigeration system. The coiled tube heat exchanger comprises a cylinder assembly, a center cylinder and a heat exchange tube, the cylinder assembly has a shell cavity for containing shell side medium, the center cylinder is arranged in the shell cavity, the heat exchange tube is spirally and layeringly wound outside the center cylinder, and the cylinder assembly has oppositely arranged first and second ends. The heat exchange tube comprises a plurality of first tubes and a plurality of second tubes, the first tubes and the second tubes are layeringly wound, one end of the first tube is located at the first end, the other end of the first tube extends to the second end and communicates with the second tube, the second tube extends from the second end to the first end, and the length of the first tube is shorter than the length of the second tube. The present application has the advantage that the tube side medium in the second tube can be arranged to counterflow with the shell side medium, so that the proportion of counterflow is greater than the proportion of parallel flow, thereby enhancing the heat exchange effect.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, in particular to a coiled tube heat exchanger and a refrigeration system. Background Art

[0002] The coiled heat exchanger is installed in the refrigeration system for heat exchange. Multiple heat exchange tubes are spirally wound around the central tube. It has the characteristics of compact design, small footprint and good heat exchange effect.

[0003] In the existing coiled tube heat exchanger with the inlet and outlet at the same end, the tube-side medium and the shell-side medium in the heat exchange tube for half of the flow length are in co-current flow, and the tube-side medium and the shell-side medium in the heat exchange tube for half of the flow length are in counter-current flow. The heat transfer effect of counter-current flow is better than that of co-current flow, so the co-current flow for half of the flow length will affect the heat transfer effect. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a coiled heat exchanger, and the technical solution is as follows:

[0005] A coil-wound heat exchanger includes a barrel assembly, a center barrel, and heat exchange tubes. The barrel assembly has a shell cavity for accommodating shell-side media. The center barrel is arranged in the shell cavity. The heat exchange tubes are spirally shaped and wound in layers around the center barrel. The barrel assembly has a first end and a second end that are oppositely arranged. The heat exchange tubes include a plurality of first tubes and a plurality of second tubes. The first tubes and the second tubes are wound in layers. One end of the first tube is located at the first end, and the other end extends to the second end and is connected to the second tube. The second tube extends from the second end to the first end. The length of the first tube is shorter than the length of the second tube.

[0006] With such an arrangement, the tube-side medium in the second tube can be arranged to flow countercurrently with the shell-side medium, so that the proportion of countercurrent flow is greater than that of cocurrent flow, thereby enhancing the heat exchange effect.

[0007] In one embodiment, a plurality of the first tubes are wound into a layer and wound around the central tube, and a plurality of the second tubes are wound around the first tube in layers.

[0008] In one embodiment, the number of the second tubes in each layer of the multiple layers of the second tubes is different.

[0009] Such an arrangement facilitates the winding of the heat exchange tube.

[0010] In one embodiment, the number of the second tubes in each layer of the second tubes gradually decreases in a direction approaching the central tube.

[0011] With such an arrangement, the closer to the central tube, the smaller the winding diameter, the fewer the strands, and the more convenient the winding.

[0012] In one embodiment, each second tube in each layer of the second tubes is connected to each first tube at the second end.

[0013] Such an arrangement can increase the countercurrent ratio.

[0014] In one embodiment, the number of the first tubes is equal to the number of the second tubes.

[0015] In one embodiment, the barrel assembly is provided with a first tube-side opening and a second tube-side opening, and the first tube-side opening and the second tube-side opening are located at the first end.

[0016] This setting is suitable for units where the medium in the tube enters and exits at the same end.

[0017] In one embodiment, a liquid separation component is provided in the first pipe-side port, and the liquid separation component is connected to the end of each first tube away from the second end; and / or a gas collection component is provided in the second pipe-side port, and the gas collection component is connected to the end of each second tube away from the second end.

[0018] This arrangement enables the tube-side medium to enter the first tube evenly.

[0019] In one embodiment, the barrel assembly is provided with a first shell-side interface and a second shell-side interface, and the first shell-side interface and the second shell-side interface are respectively provided at the first end and the second end.

[0020] The present invention also provides the following technical solutions:

[0021] A refrigeration system includes the above-mentioned coiled tube heat exchanger.

[0022] Compared with the prior art, the present invention provides a coiled-tube heat exchanger that divides the heat exchange tubes entering and exiting the same end into a first tube and a second tube. The tube-side medium in the first tube and the tube-side medium in the second tube flow in opposite directions, and the length of the first tube is shorter than that of the second tube. This makes the flow length of the tube-side medium in the first tube shorter than the flow length in the second tube. The flow length of the co-current flow with the shell-side medium can be set to be shorter than the flow length of the counter-current flow, thereby enhancing the heat exchange effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic structural diagram of a coiled-tube heat exchanger provided by the present invention;

[0024] Figure 2 is a perspective view of a coiled tube heat exchanger;

[0025] Figure 3 for Figure 2 A partial enlarged view of the

[0026] Figure 4 Schematic diagram of the structure of the central tube and heat exchange tube;

[0027] Figure 5 for Figure 4 Right view of .

[0028] The symbols in the figure mean the following:

[0029] 100. Wrap-around heat exchanger; 101. First end; 102. Second end; 10. Cylinder assembly; 11. Shell cavity; 12. First shell-side interface; 121. First flange pipe; 13. Second shell-side interface; 131. Second flange pipe; 14. Cylinder; 15. First cover; 16. Second cover; 17. First tube-side port; 18. Second tube-side port; 20. Center tube; 30. Heat exchange tube; 31. First tube; 32. Second tube; 33. U-shaped tube; 34. Capillary tube; 40. Liquid separation assembly; 41. Distributor; 411. Liquid separation hole; 412. Liquid inlet head; 413. Liquid outlet head; 414. Liquid separation cone; 50. Gas collecting assembly. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0031] It should be noted that when a component is referred to as being "mounted on" another component, it may be directly on the other component or there may be a central component. When a component is considered to be "set on" another component, it may be directly set on the other component or there may be a central component. When a component is considered to be "fixed to" another component, it may be directly fixed to the other component or there may be a central component.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0033] See also Figure 1 and Figure 2 , Figure 1 This is a schematic structural diagram of a coiled-tube heat exchanger 100 provided by the present invention. Figure 2 The present invention provides a coiled-tube heat exchanger 100, which is installed in a refrigeration system for heat exchange. The coiled-tube heat exchanger 100 can be used as both an evaporator and a condenser.

[0034] Specifically, the coiled heat exchanger 100 includes a barrel assembly 10, a central barrel 20, and heat exchange tubes 30. The barrel assembly 10 defines a shell 11. The heat exchange tubes 30 spirally and layeredly surround the outer side of the central barrel 20. The central barrel 20 and heat exchange tubes 30 are located within the shell 11. The spiral shape enhances the shock resistance of the heat exchange tubes 30 and mitigates the expansion and contraction stress caused by varying temperatures. Shell 11 allows the flow of shell-side media, while the heat exchange tubes 30 allow the flow of tube-side media.

[0035] Furthermore, the barrel assembly 10 includes a barrel 14, a first cover 15, and a second cover 16. The first cover 15 and the second cover 16 are respectively disposed at both ends of the barrel 14. The first cover 15, the second cover 16, and the barrel 14 enclose a shell cavity 11, and the shell-side medium flows in the shell cavity 11. The first cover 15 and the second cover 16 are hemispherical in shape. Of course, the shapes of the first cover 15 and the second cover 16 are not limited to this. The first cover 15 and the second cover 16 can also be 1 / 3 spherical, etc.

[0036] In other embodiments, two blind covers (not shown) may be used instead of the first cover 15 and the second cover 16. The blind covers are disc-shaped and are respectively provided at both ends of the cylinder 14 to seal the shell cavity 11, thereby saving costs.

[0037] Please continue to see Figure 2 , Figure 2 The figure shows a perspective view of a coiled-tube heat exchanger 100. The coiled-tube heat exchanger 100 has a first end 101 and a second end 102, which are positioned opposite each other. A first shell-side port 12 and a second shell-side port 13 are formed on the barrel assembly 10. Both the first shell-side port 12 and the second shell-side port 13 communicate with the shell cavity 11. The first shell-side port 12 is located at the second end 102, while the second shell-side port 13 is located at the first end 101. Shell-side medium flows into the shell cavity 11 through the first shell-side port 12, exchanges heat with the tube-side medium in the heat exchange tubes 30, and then flows out through the second shell-side port 13. Alternatively, the shell-side medium flows into the shell cavity 11 through the second shell-side port 13 and then flows out through the first shell-side port 12.

[0038] In this embodiment, the first shell-side interface 12 and the second shell-side interface 13 are both provided on the cylinder 14. In other embodiments, the first shell-side interface 12 and the second shell-side interface 13 may also be provided on the second cover 16 and the first cover 15, respectively. It should be noted that in this embodiment, the tube-side medium is refrigerant and the shell-side medium is water. In other embodiments, depending on the properties of the medium, an appropriate medium may be selected for the tube-side and another medium may be selected for the shell-side.

[0039] A first flange pipe 121 is provided in the first shell-side interface 12, and a second flange pipe 131 is provided in the second shell-side interface 13. Since the shell-side medium is water in this embodiment, the first flange pipe 121 and the second flange pipe 131 are connected to the external water pipe. The water pipe is relatively large, and the flange connection can enhance the connection strength.

[0040] The barrel assembly 10 is provided with a first pipe-side port 17 and a second pipe-side port 18 for the circulation of the pipe-side medium. The first pipe-side port 17 and the second pipe-side port 18 can be provided on the first cover 15 or the barrel 14 .

[0041] In this embodiment, the first tube-side port 17 and the second tube-side port 18 are both provided on the first cover 15 . The first tube-side port 17 and the second tube-side port 18 are located at the same end to accommodate a unit in which tube-side media enter and exit at the same end.

[0042] Specifically, a liquid separator 40 is provided in the first tube-side port 17 and connected to one end of the heat exchange tube 30. When the coil-wound heat exchanger 100 is used as an evaporator, the liquid separator 40 is used to evenly distribute the tube-side medium to each heat exchange tube 30.

[0043] Preferably, a gas collecting assembly 50 is provided in the second tube-side port 18, and the gas collecting assembly 50 is connected to one end of the heat exchange tube 30. When the coil-wound heat exchanger 100 is used as an evaporator, the gas collecting assembly 50 is used to collect the tube-side medium flowing out of each heat exchange tube 30 and flow it into the pipeline of the refrigeration system.

[0044] In this embodiment, the liquid separation component 40 and the gas collecting component 50 are both distributors 41, and a plurality of liquid separation holes 411 are provided on the distributor 41. One end of the heat exchange tube 30 is welded to the liquid separation hole 411 through the capillary 34, and the other end of the heat exchange tube 30 is welded to the liquid separation hole 411 of the gas collecting component 50 through the capillary 34.

[0045] See Figure 3 , Figure 3 for Figure 2: A partially enlarged view in FIG. In this embodiment, the distributor 41 is a liquid separator. The liquid separator includes a liquid inlet head 412, a liquid outlet head 413 and a liquid separator cone 414, and the liquid inlet head 412, the liquid outlet head 413 and the liquid separator cone 414 are integrally formed. The liquid separator cone 414 is located between the liquid inlet head 412 and the liquid outlet head 413. The liquid inlet head 412 is arranged in the first pipe-side port 17 or the second pipe-side port 18. The liquid inlet head 412 has a flow channel (not shown) for supplying the pipe-side medium in and out. The liquid outlet head 413 is located in the shell cavity 11. The liquid separator hole 411 is provided on the liquid outlet head 413. The liquid separator hole 411 extends from the surface of the liquid outlet head 413 away from the liquid separator cone 414 to the liquid separator cone 414, and is connected to the flow channel of the liquid inlet head 412. The axis of the liquid separator hole 411 is tilted relative to the axis of the liquid separator head so that the pipe-side medium is evenly distributed. In other embodiments, the distributor 41 may be a distributor 41 having a liquid separation plate therein. It should be noted that when the liquid separation head is used as the liquid separation component 40, the pipe-side medium enters from the liquid inlet head 412 and flows out from the liquid outlet head 413. When the liquid separation head is used as the gas collection component 50, the pipe-side medium enters from the liquid outlet head 413 and flows out from the liquid inlet head 412.

[0046] In other embodiments, the liquid separation assembly 40 and the gas collection assembly 50 may also be tube sheets (not shown). The tube sheets are disposed within the first tube-side port 17 and the second tube-side port 18. The tube sheets are provided with fixing holes (not shown), and the inlets of the heat exchange tubes 30 are expansion-connected to the fixing holes of the tube sheets. In other embodiments, the liquid separation assembly 40 may be a distributor 41 such as a liquid separation head, and the gas collection assembly 50 may be a tube sheet. Alternatively, the liquid separation assembly 40 may be a tube sheet, the gas collection assembly 50 may be a distributor 41, and the gas collection assembly 50 may not be disposed within the second tube-side port 18.

[0047] In this embodiment, there is only one first pipe-side port 17 and one second pipe-side port 18. In other embodiments, when the refrigeration system is a multi-system with multiple compressors, multiple first pipe-side ports 17 and second pipe-side ports 18 are provided, and the multiple compressors are connected to the first pipe-side port 17 or the second pipe-side port 18 in a one-to-one correspondence. When the coil-wound heat exchanger 100 is used as an evaporator, the multiple compressors are connected to the second pipe-side port 18 in a one-to-one correspondence. When the coil-wound heat exchanger 100 is used as a condenser, the multiple compressors are connected to the first pipe-side port 17 in a one-to-one correspondence.

[0048] See Figure 4 and Figure 5 , Figure 4 is a structural diagram of the central tube 20 and the heat exchange tube 30, Figure 5 for Figure 4The heat exchange tube 30 includes a first tube 31 and a second tube 32. There are multiple first tubes 31 and multiple second tubes 32. The multiple first tubes 31 and the multiple second tubes 32 are spirally wound. One end of the first tube 31 is located at the first end 101, and the other end extends to the second end 102 and communicates with the second tube 32. The second tube 32 extends from the second end 102 to the first end 101. The length of the second tube 32 is longer than the length of the first tube 31. In other words, the flow length of the tube-side medium in the first tube 31 is shorter than the flow length in the second tube 32. It should be noted that in the present invention, the length of the first tube 31 refers to the total length of the first tube 31, that is, the length of the first tube 31 after being wound into a spiral shape, not the length of the first tube 31 along the axis of the central tube 20. The length of the second tube 32 refers to the total length of the second tube 32, that is, the length of the second tube 32 after being wound into a spiral shape, not the length of the second tube 32 along the axis of the central tube 20.

[0049] It can be understood that such an arrangement can set the tube-side medium in the second tube 32 to flow countercurrently with the shell-side medium, so that the proportion of countercurrent is greater than the proportion of cocurrent, thereby enhancing the heat exchange effect.

[0050] Furthermore, the number of first tubes 31 is equal to the number of second tubes 32, and the first tubes 31 are connected to the second tubes 32 in a one-to-one correspondence. The first tubes 31 and the second tubes 32 can be connected via a U-shaped tube 33, or by bending one end of the first tube 31 and then welding it to the second tube 32. The liquid separation assembly 40 is connected to the first tube 31 via a capillary tube 34, and the gas collection assembly 50 is connected to the second tube 32 via a capillary tube 34.

[0051] Please continue to see Figure 5 , Figure 5 for Figure 4 Right side view. In this embodiment, multiple first tubes 31 are wound into a single layer and wrapped around the center tube 20, and multiple second tubes 32 are wound in layers around the first tubes 31. In other embodiments, multiple first tubes 31 may be wound into multiple layers, or wrapped around the second tubes 32, and the second tubes 32 may be wound around the center tube 20. Alternatively, the first tubes 31 may be wound between multiple layers of second tubes 32.

[0052] Each second tube 32 in each layer of second tubes 32 is connected to each first tube 31 at the second end 102, that is, the flow direction of the tube-side medium in all the second tubes 32 is the same in the axial direction, flowing from the first end 101 to the second end 102, or from the second end 102 to the first end 101. The tube-side medium in all the second tubes 32 can form a countercurrent with the shell-side medium, thereby increasing the countercurrent ratio.

[0053] The number of second tubes 32 in each layer of the multi-layer second tubes 32 is different. Since the second tubes 32 are wound around the first tube 31 in layers, the wound diameters are different, and the number of second tubes 32 in each layer is different, which facilitates winding.

[0054] Preferably, the number of second tubes 32 in each layer of second tubes 32 gradually decreases as it approaches the central tube 20. Since the winding diameter becomes smaller and the number of tubes decreases as it approaches the central tube 20, winding becomes more convenient.

[0055] For example, if heat exchange tubes 30 are arranged in four layers, the first layer comprises first tubes 31, and the second, third, and fourth layers comprise second tubes 32. The tube-side medium in first tubes 31 flows concurrently with the shell-side medium, while the tube-side medium in second tubes 32 flows countercurrently with the shell-side medium. There are 30 first tubes 31 in the first layer, with a flow path length of 6.5 meters. The coiled length of the first layer accounts for approximately 25% of the total length of heat exchange tubes 30. The number of second tubes 32 in the second layer can be set to 9, 10 in the third layer, and 11 in the fourth layer, resulting in approximately 75% of the flow path length being countercurrent with the shell-side medium. If the heat exchange tubes 30 are arranged in six layers, with the first layer consisting of first tubes 31 and the second tubes 32 in five layers, the first layer will have 30 first tubes 31, the second layer will have four second tubes 32, the third layer will have five second tubes 32, the fourth layer will have six second tubes 32, the fifth layer will have seven second tubes 32, and the sixth layer will have eight second tubes 32. This means that approximately 80% of the flow path length can form a countercurrent with the shell-side medium. As the number of layers of second tubes 32 increases, the countercurrent ratio increases, further enhancing heat exchange performance.

[0056] In the heat pump air-conditioning system, during cooling, the first tube 31 is used as the inlet tube and the second tube 32 is used as the outlet tube, and the shell-side medium flows in from the first shell-side interface 12 and flows out from the second shell-side interface 13; during heating, since the flow direction of the tube-side medium is opposite, the second tube 32 is the inlet tube and the first tube 31 is the outlet tube, the flow direction of the shell-side medium can be set to be opposite to that during cooling, flowing in from the second shell-side interface 13 and flowing out from the first shell-side interface 12, and the tube-side medium in the second tube 32 forms a countercurrent with the shell-side medium, so that during heating, the countercurrent ratio is still greater than the forward flow ratio, thereby enhancing the heat exchange performance.

[0057] The spiral direction of the first tube 31 is opposite to that of the adjacent second tube 32 , and the spiral directions of the adjacent second tubes 32 are opposite, which can enhance the turbulence of the shell-side medium between the heat exchange tubes 30 , strengthen heat exchange, and improve heat exchange efficiency.

[0058] Multiple first tubes 31 in the same layer are spaced apart, multiple second tubes 32 in the same layer are spaced apart, the first tubes 31 and the second tubes 32 of the adjacent layer are spaced apart, and the second tubes 32 of the adjacent layers are spaced apart, so that the shell-side medium can enter the gaps between layers and the gaps between tubes to fully exchange heat with the tube-side medium.

[0059] A gasket strip (not shown) is provided between the multiple second tubes 32 in the same layer to maintain the inter-tube spacing between the multiple second tubes 32 in the same layer; a gasket strip (not shown) is provided between the first tube 31 and the second tube 32 in the adjacent layer to maintain the inter-layer spacing between the first tube 31 and the second tube 32; a gasket strip (not shown) is also provided between the second tubes 32 in adjacent layers to maintain the inter-layer spacing between the second tubes 32 in adjacent layers.

[0060] Specifically, a wrapping tube (not shown) is provided between the outermost heat exchange tube 30 and the inner wall of the barrel 14. The wrapping tube is wrapped around the outermost heat exchange tube 30. In this embodiment, the wrapping tube is wrapped around the outermost second tube 32 and fixed to the inner wall of the barrel 14. The wrapping tube acts as a flow guide, preventing the shell-side medium from flowing directly from between the outermost heat exchange tube 30 and the inner wall of the shell cavity 11 to the other end of the barrel 14, thereby affecting the heat exchange effect. At the same time, it can reduce the friction between the inner wall of the barrel 14 and the heat exchange tube 30, preventing the heat exchange tube 30 from being ruptured by friction and causing leakage.

[0061] The heat exchange tube 30 may be provided with threads on its inner wall (not shown), or on its outer wall, or both inside and outside the heat exchange tube 30 , to increase the heat exchange area of ​​the heat exchange tube 30 .

[0062] The present invention further provides a refrigeration system, comprising the coil-wound heat exchanger 100 .

[0063] When the coiled heat exchanger 100 is used as an evaporator, the inlet of the coiled heat exchanger 100 is connected to a throttle valve (not shown), and the outlet is connected to a gas-liquid separator or a compressor (not shown); when the coiled heat exchanger 100 is used as a condenser, the inlet of the coiled heat exchanger 100 is connected to a compressor, and the outlet is connected to a throttle valve.

[0064] Low-temperature, low-pressure gaseous refrigerant enters the compressor through its intake port. The compressor works to convert it to high-temperature, high-pressure gaseous refrigerant, which is then discharged from the compressor exhaust port into the condenser. The high-temperature, high-pressure refrigerant exchanges heat in the condenser, becoming a high-temperature, high-pressure liquid refrigerant. The refrigerant then passes through a throttle valve, throttling it back to a low-temperature, low-pressure gas-liquid two-phase state. The refrigerant then enters the evaporator, absorbing heat and evaporating, before entering the compressor, repeating the cycle. When the refrigeration system needs to switch modes, from cooling to heating, the medium in the condenser and evaporator tubes flows in reverse.

[0065] During operation of the coiled heat exchanger 100, when the coiled heat exchanger 100 is used as an evaporator, the tube-side medium enters from the liquid separator assembly 40, is evenly distributed by the liquid separator assembly 40, and then enters each first tube 31. The shell-side medium enters from the first shell-side interface 12, forming a downstream flow with the tube-side medium in the first tube 31. The medium in the first tube 31 enters the second tube 32 and continues to form a countercurrent flow with the shell-side medium. After heat exchange, the shell-side medium flows out from the second shell-side interface 13 and out from the gas collecting assembly 50. When the mode is switched, for example, from cooling mode to heating mode, the coiled heat exchanger 100 is used as a condenser. The tube-side medium enters from the gas collecting assembly 50, is distributed by the gas collecting assembly 50, and enters the second tube 32. The shell-side medium enters from the second shell-side interface, forming a countercurrent flow with the tube-side medium in the second tube 32, and then forms a downstream flow with the medium in the first tube 31.

[0066] The present invention divides the heat exchange tube 30, through which the tube-side medium enters and exits at the same end, into a first tube 31 and a second tube 32. The tube-side medium in the first tube 31 and the tube-side medium in the second tube 32 flow in opposite directions. The length of the first tube 31 is shorter than that of the second tube 32. As a result, the flow length of the tube-side medium in the first tube 31 is shorter than that in the second tube 32. The flow length of the downstream medium can be set shorter than the upstream medium, thereby enhancing the heat exchange effect.

[0067] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0068] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A coil-wound heat exchanger, comprising a barrel assembly (10), a central barrel (20), and heat exchange tubes (30); the barrel assembly (10) has a shell cavity (11) for accommodating a shell-side medium; the central barrel (20) is disposed in the shell cavity (11); the heat exchange tubes (30) are spirally wound around the central barrel (20) in layers; the barrel assembly (10) has a first end (101) and a second end (102) disposed opposite to each other; It is characterized by: The heat exchange tube (30) includes a plurality of first tubes (31) and a plurality of second tubes (32), wherein the first tubes (31) and the second tubes (32) are wound in layers, one end of the first tube (31) is located at the first end (101), and the other end extends to the second end (102) and is connected to the second tube (32), and the second tube (32) extends from the second end (102) to the first end (101), and the length of the first tube (31) is shorter than the length of the second tube (32), and the plurality of first tubes (31) are wound into a layer and wound outside the central tube (20), and the plurality of second tubes (32) are wound in layers outside the first tube (31), and the number of the second tubes (32) in each layer of the plurality of second tubes (32) is different, and the number of the second tubes (32) in each layer of the second tubes (32) gradually decreases along the direction close to the central tube (20).

2. The coiled tube heat exchanger according to claim 1, characterized in that: Each second tube (32) in each layer of the second tubes (32) is connected to each first tube (31) at the second end (102).

3. The coiled tube heat exchanger according to claim 1, characterized in that: The number of the first tubes (31) is equal to the number of the second tubes (32).

4. The coiled tube heat exchanger according to claim 1, characterized in that: The barrel assembly (10) is provided with a first tube-side opening (17) and a second tube-side opening (18), and the first tube-side opening (17) and the second tube-side opening (18) are both located at the first end (101).

5. The coiled tube heat exchanger according to claim 4, characterized in that: A liquid separation component (40) is provided in the first pipe-side port (17), and the liquid separation component (40) is connected to one end of each first pipe (31) away from the second end (102); and / or a gas collection component (50) is provided in the second pipe-side port (18), and the gas collection component (50) is connected to one end of each second pipe (32) away from the second end (102).

6. The coiled tube heat exchanger according to claim 1, characterized in that: The barrel assembly (10) is provided with a first shell-side interface (12) and a second shell-side interface (13), and the first shell-side interface (12) and the second shell-side interface (13) are respectively provided at the first end (101) and the second end (102).

7. A refrigeration system, characterized in that: It comprises the coiled tube heat exchanger according to any one of claims 1 to 6.

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