Large direct expansion unit

Abstract

The utility model discloses a large-scale direct expansion unit, which comprises a box body, an air inlet, an air outlet, a heat exchanger and a heat exchanger, the refrigerating unit comprises a main machine section and an evaporation section which are arranged in the box body, the evaporation section is arranged between the air inlet and the air outlet, the main machine section comprises a compressor used for compressing a refrigerant and a radiator used for dissipating heat of the refrigerant, and the evaporation section comprises an evaporator communicated with the compressor and the radiator; the fan section is arranged between the evaporation section and the air outlet and comprises a fan wall composed of a plurality of fans, the fans comprise a plurality of fan rows which are sequentially distributed in the horizontal direction, each fan row comprises a plurality of fans which are arranged in the vertical direction, and when the fan wall works, the fan wall is provided with a plurality of air outlets. And the fan wall extracts air which enters the box body from the air inlet and exchanges heat with the evaporator, and conveys the air to the outside through the air outlet.

Description

Technical Field

[0001] The utility model relates to the technical field of large-scale refrigeration devices, in particular to a large-scale direct expansion unit. Background Art

[0002] Direct expansion units, that is, units with their own compressors, in which the liquid refrigerant in the refrigeration system directly evaporates (expands) in its evaporator coil to absorb heat from the air outside the coil and cool it. Direct expansion units include various forms of air conditioning products. In subway construction, large-scale subway magnetic levitation centrifugal water-cooled direct expansion units are usually made into integral structures and placed in specific spaces such as machine rooms.

[0003] The Chinese patent with publication number CN206973790U discloses a large water-cooled direct expansion unit. Its structure includes multiple unit modules that realize independent functions, and the unit modules have a frame structure, and the frame structures are sealed and connected by flexible connecting sections. At the same time, each unit module can maintain the independence of production and installation, so it can be independently unloaded, processed, assembled and inspected, and can be hoisted and transported separately. The evaporation section of the patent adopts a single centrifugal fan, the wind field is not uniform, the flow efficiency is not high, and the noise is relatively large. Summary of the invention

[0004] The utility model aims to provide a large direct expansion unit which can improve air flow efficiency and reduce air flow noise.

[0005] The utility model discloses a large direct expansion unit, comprising:

[0006] A box body, comprising an air inlet and an air outlet for outputting cold air;

[0007] A refrigeration unit, comprising a main unit section and an evaporation section arranged in the box, wherein the evaporation section is arranged between the air inlet and the air outlet, the main unit section includes a compressor for compressing a refrigerant and a radiator for dissipating heat from the refrigerant, and the evaporation section includes an evaporator connected to the compressor and the radiator;

[0008] The fan section is arranged between the evaporation section and the air outlet, and includes a fan wall composed of multiple fans. The multiple fans include multiple fan columns distributed in sequence along the horizontal direction, and each fan column includes multiple fans arranged along the vertical direction. When working, the fan wall draws air that enters the box through the air inlet and undergoes heat exchange with the evaporator and transports the air to the outside through the air outlet.

[0009] In some embodiments, the multiple fans of the fan array are evenly distributed in the vertical direction, and the multiple fan arrays are evenly distributed in the horizontal direction.

[0010] In some embodiments, the plurality of fans constituting the fan wall are arranged in rows and columns, and the number of rows and columns of the plurality of fans is the same.

[0011] In some embodiments, it also includes a silencer section disposed between the fan section and the air outlet, and the air output by the fan wall is transported to the air outlet after the air is denoised by the silencer section.

[0012] In some embodiments, the silencer section includes a plurality of silencers distributed in the horizontal direction and in the vertical direction, and adjacent silencers in the horizontal direction and in the vertical direction are arranged at intervals. The silencer includes a silencer cavity, and a plurality of silencer holes are provided on the surface of the silencer shell facing the adjacent silencer, and the silencer holes are connected to the silencer cavity.

[0013] In some embodiments, the silencer section includes a first mounting frame and a second mounting frame, the first mounting frame is provided with a plurality of first enclosed shells corresponding one-to-one to the plurality of silencers, the second mounting frame is provided with a plurality of second enclosed shells corresponding one-to-one to the plurality of silencers, the silencer is a cylindrical silencer, the silencer is arranged between the first mounting frame and the second mounting frame, and each of the silencers is closed and connected by the first enclosed shell and the second enclosed shell at both ends along the axial direction, and the first mounting frame and the second mounting frame are arranged along the flow direction of the air delivered to the air outlet.

[0014] In some embodiments, along the flow direction of air passing through the silencer section, the first enclosed shell is located upstream of the second enclosed shell, and the radial outer side of the outer surface of the first enclosed shell facing the fan section is inclined relative to the radial inner side along the flow direction of the air.

[0015] In some embodiments, the plurality of mufflers are aligned in the horizontal direction and in the vertical direction to form a plurality of vertical air flow channels spaced apart in the horizontal direction and horizontal air flow channels spaced apart in the vertical direction between the plurality of mufflers.

[0016] In some embodiments, a layered sound absorbing material is also provided in the cavity of the muffler.

[0017] In some embodiments, the muffler is a rectangular muffler, and the multiple mufflers have the same shape.

[0018] In some embodiments, the main unit section includes an isolation cover disposed in the box body, the radiator is disposed in the isolation cover, and the isolation cover is a closed structure to prevent the refrigerant leaking from the radiator from flowing out of the isolation cover and entering the air flowing in the box body.

[0019] In some embodiments, the compressor is also disposed in the isolation cover.

[0020] In some embodiments, it also includes a pressure relief pipe that passes through the isolation cover and the box body to discharge the refrigerant outside the box body, and a safety valve that is arranged between the pressure relief pipe and the refrigerant flow pipeline of the radiator. The safety valve is configured to open when the pressure of the refrigerant in the refrigerant flow pipeline of the radiator exceeds a safety threshold to discharge the refrigerant outside the box body through the pressure relief pipe.

[0021] In some embodiments, it also includes a filter section arranged between the air inlet and the evaporation section, the filter section is used to filter the air flowing in from the air inlet before it flows into the evaporation section, the filter section includes an electrostatic precipitator for electrostatically removing dust from the air and a coarse filter located upstream of the electrostatic precipitator along the air flow direction for filtering particulate matter in the air.

[0022] In some embodiments, the large direct expansion unit is a water-cooled direct expansion unit.

[0023] Based on the large direct expansion unit provided by the utility model, a fan wall is arranged between the evaporation section and the air outlet. The fan wall is composed of multiple fan rows distributed in the horizontal direction, and the fan row is composed of multiple fans arranged in the vertical direction. The multiple fans form the fan wall to extract the air cooled by the evaporation section and transport it to the air outlet, which can make the wind field more uniform, improve the air flow efficiency, and reduce vibration and noise during air flow.

[0024] Other features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0026] Figure 1 It is a schematic structural diagram of a box of a large direct expansion unit according to some embodiments of the utility model;

[0027] Figure 2 For Figure 1 The schematic diagram of the structure inside the box shown;

[0028] Figure 3 for Figure 2 The structural schematic diagram of the fan wall shown;

[0029] Figure 4 for Figure 2 The structural schematic diagram of the muffler section shown;

[0030] Figure 5 for Figure 2 A schematic diagram of the structure of a portion of the host section shown;

[0031] Figure 6 for Figure 2 The structural schematic diagram of the filtration section is shown. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means a limitation on the utility model and its application or use. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0033] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the utility model. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0034] In the description of the present invention, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0037] like Figures 1 to 3 As shown, the large direct expansion unit of this embodiment includes a box body 1, a refrigeration unit and a fan section 23.

[0038] The housing 1 includes an air inlet 11 and an air outlet 12 for outputting cold air. When the large direct expansion unit is working, air enters the housing through the air inlet 11, and flows out from the air outlet 12 after being cooled by the refrigeration unit to cool the external environment. When the large direct expansion unit of this embodiment is applied to the underground subway station space, the air outlet 12 is used to output cold air to the underground space, machine room and other spaces of the subway station. There are multiple air inlets 11, including a return air inlet for returning the air output from the air outlet 12 and a new air inlet for introducing fresh air from the external atmospheric environment into the housing.

[0039] The refrigeration unit includes a main section 21 and an evaporation section 22 arranged in the box 1. The evaporation section 22 is arranged between the air inlet 11 and the air outlet 12. The main section 21 includes a compressor for compressing the refrigerant and a radiator 211 for dissipating heat from the refrigerant. The evaporation section 22 includes an evaporator connected to the compressor and the radiator 211. The refrigerant is compressed by the compressor, then enters the radiator 211 to dissipate heat, and then enters the evaporator of the evaporation section 22 after throttling and expansion through the throttling device. In the evaporator, the refrigerant exchanges heat with the air passing through the evaporator to cool the air, and the cooled air is output through the air outlet 12.

[0040] The fan section 23 is arranged between the evaporation section 22 and the air outlet 12. The fan section 23 includes a fan wall composed of a plurality of fans 232. The plurality of fans 232 include a plurality of fan columns 231 distributed in sequence along the horizontal direction. Each fan column 231 includes a plurality of fans 232 arranged in sequence along the vertical direction. The plurality of fan columns are arranged in sequence along the horizontal direction to form a fan wall similar to a matrix. When working, the fan wall draws air that enters the box body 1 through the air inlet 11 and undergoes heat exchange with the refrigerant of the evaporator, and the fan wall transports the drawn air to the outside through the air outlet 12. In the case of Figure 2 In the embodiment shown, the fan wall is directly opposite to the evaporation section, and the fan wall can achieve coverage of a larger area of ​​the evaporation section. The fan wall can cover and draw the cooled air output from the evaporation section in the horizontal and vertical directions, making the wind field more uniform, and making the air flow more uniform, reducing vibration and noise, and also helping to improve the heat exchange effect between the air and the evaporator.

[0041] The large direct expansion unit of this embodiment is provided with a fan wall between the evaporation section 22 and the air outlet 12. The fan wall is composed of a plurality of fan columns 231 distributed in the horizontal direction. The fan column 231 is composed of a plurality of fans 232 arranged in the vertical direction. The plurality of fans 232 form the fan wall to extract the air cooled by the evaporation section 22 and transport it to the air outlet 12, which can make the wind field more uniform, improve the air flow efficiency, and reduce the vibration and noise during the air flow.

[0042] In some embodiments, Figure 3 As shown, the multiple fans 232 of the fan array 231 are evenly distributed in the vertical direction, and the multiple fan arrays 231 are evenly distributed in the horizontal direction. The fans of the fan wall of this embodiment are arranged more evenly in the horizontal and vertical directions, so that when the fan wall extracts the air output from the evaporation section, the wind field can be more evenly distributed in the horizontal and vertical directions, and the vibration and noise during air flow are further reduced.

[0043] In some embodiments, Figure 3 As shown, the multiple fans 232 constituting the fan wall are arranged in rows and columns, and the number of rows and columns of the multiple fans 232 is the same. Figure 3 In the embodiment shown, a plurality of fans are arranged in 3 rows and 3 columns. The fans of the fan wall of this embodiment are more symmetrical in spatial arrangement, so that the wind field formed when the fan wall extracts air can be more uniform, which further helps to reduce vibration and noise during air flow.

[0044] In some embodiments, Figure 2 and Figure 4As shown, the large direct expansion unit also includes a muffler section 24 disposed between the fan section 23 and the air outlet 12, and the air outputted from the fan wall is delivered to the air outlet 12 after being noise-reduced by the muffler section 24. The air outputted from the fan wall is first noise-reduced by the muffler section 24 before being outputted through the air outlet 12, so that the output air noise can be further reduced.

[0045] In some embodiments, Figure 4 As shown, the muffler section 24 includes a plurality of mufflers 245 distributed in the horizontal direction and in the vertical direction, and the adjacent mufflers 245 in the horizontal direction and in the vertical direction are arranged at intervals, and the muffler 245 includes a muffler cavity, which is a closed cavity provided in the muffler and is connected to the outside only through the muffler hole. A plurality of muffler holes are provided on the surface of the shell of the muffler 245 facing the adjacent muffler 245, and the muffler holes are connected to the muffler cavity. In the silencer section 24 of the present embodiment, a plurality of silencers 245 are arranged in the horizontal direction and in the vertical direction to form a matrix-like silencer arrangement. The silencers adjacent to each other in the horizontal direction and in the vertical direction are arranged at intervals, so that a flow channel for air to pass through can be formed between the silencers. The silencer includes a silencer cavity, and the silencer is provided with silencer holes connected to the silencer cavity on the surface facing the adjacent silencer. When the air flows along the fluid channel formed by the intervals between the adjacent silencers, the air column in the silencer hole connected to the silencer cavity can vibrate back and forth, thereby resisting noise of some frequencies in the air passing through the silencer hole in the flow channel, and achieving a good noise reduction effect while the air flows smoothly through the fluid channel.

[0046] In some embodiments, Figure 2 and Figure 4As shown, the silencer section 24 includes a first mounting frame 241 and a second mounting frame 242. The first mounting frame 241 is provided with a plurality of first closed shells 243 corresponding to the plurality of mufflers 245 one by one. The second mounting frame 242 is provided with a plurality of second closed shells 244 corresponding to the plurality of mufflers 245 one by one. The muffler 245 is a cylindrical muffler. The muffler 245 is arranged between the first mounting frame 241 and the second mounting frame 242, and each muffler 245 is closed and connected by a first closed shell 243 and a second closed shell 244 at both ends along the axial direction. The first mounting frame 241 and the second mounting frame 242 are arranged along the flow direction of the air delivered to the air outlet 12, that is, along the flow direction of the air passing through the silencer section 24, the first mounting frame 241 and the second mounting frame 242 are located one upstream and one downstream. In the embodiment shown in the figure, the first mounting frame 241 is located upstream of the second mounting frame 242. The silencer is a columnar silencer, including a prismatic silencer and a cylindrical silencer, and in the embodiment shown in the figure, it is a rectangular silencer. Since its axial ends are closed and connected by the first closed shell and the second closed shell, when the air output from the fan wall flows to the silencer section, the first closed shell and the second closed shell will block the air from entering the silencer along the axial direction of the columnar silencer, avoiding greater flow resistance to the air, and the air can flow more smoothly through the flow channel formed by the interval between adjacent silencers. At the same time, in some embodiments, the first closed shell and the second closed shell can also assist in forming a silencer cavity in the silencer to improve the noise reduction effect.

[0047] In some embodiments, Figure 2 and Figure 4 As shown, along the flow direction of air passing through the silencer section 24, the first enclosed shell 243 is located upstream of the second enclosed shell 244, and the radial outer side of the outer surface of the first enclosed shell 243 facing the fan section 23 is inclined relative to the radial inner side along the flow direction of the air. Figure 4 The arrow in the figure indicates the flow direction of the air, and the outer surface of the first closed shell 243 faces the air output from the fan wall. In this embodiment, the radial outer side of the outer surface of the first closed shell is inclined toward the radial inner side downstream along the flow direction of the air, so that the outer surface of the first closed shell forms a shape that is convex in the middle toward the upstream of the air flow direction. When the air hits the first closed shell, the shape of the first closed shell can guide the air to the air flow channel on the side of the first closed shell, reduce the air flow resistance, make the air flow smoother, and also help save energy and reduce noise.

[0048] In some embodiments, Figure 4As shown, a plurality of silencers 245 are aligned in the horizontal direction and in the vertical direction, so as to form a plurality of vertical air flow channels arranged at intervals in the horizontal direction and a plurality of horizontal air flow channels arranged at intervals in the vertical direction between the plurality of silencers 245. In the embodiment shown in the figure, the air flow channels are horizontal air flow channels in the shape of straight lines arranged neatly and vertical air flow channels in the shape of straight lines perpendicularly intersecting the horizontal air flow channels. The vertical air flow channels and horizontal air flow channels of this embodiment can make the air flow more uniform and smooth, and also help to improve the noise reduction effect.

[0049] In some embodiments, a layered sound absorbing material is further provided in the cavity of the muffler 245. That is, layers of sound absorbing materials are provided in the muffler cavity, which can further improve the noise reduction effect.

[0050] In some embodiments, Figure 4 As shown, the muffler 245 is a rectangular muffler, and the shapes of the multiple mufflers 245 are the same. The air flow channel of the muffler section of this embodiment is more uniform and smooth, and the noise reduction of the air is also more uniform and effective.

[0051] In some embodiments, Figure 1 , Figure 2 and Figure 5 As shown, the main engine section 21 includes an isolation cover 212 disposed in the housing 1, and a radiator 211 is disposed in the isolation cover 212. The isolation cover 212 is a closed structure to prevent the refrigerant leaking from the radiator 211 from flowing out of the isolation cover 212 and entering the air flowing in the housing 1. In some embodiments, the radiator is a shell and tube heat exchanger, and the compressor is also disposed in the isolation cover 212.

[0052] The isolation cover separates the radiator 211 and / or compressor located therein from the flow aperture of the air in the box, which can prevent the refrigerant leaking from the radiator 211 or the compressor from entering the flowing air and being output through the air outlet along with the air, and can also isolate noise.

[0053] In some embodiments, the large direct expansion unit further includes a pressure relief pipe 213 passing through the isolation cover 212 and the box body 1 to discharge the refrigerant to the outside of the box body 1, and a safety valve 214 provided between the pressure relief pipe 213 and the refrigerant flow pipeline of the radiator 211. The safety valve 214 is configured to open when the pressure of the refrigerant in the refrigerant flow pipeline of the radiator 211 exceeds the safety threshold to discharge the refrigerant to the outside of the box body 1 through the pressure relief pipe 213. The safety valve 214 is used to detect the pressure of the refrigerant flow pipeline of the radiator, and opens to release the pressure when it exceeds the safety pressure. After the safety valve is opened, the refrigerant flow pipeline discharges the refrigerant to the machine room or collection tank and other facilities outside the box through the pressure relief pipe 213.

[0054] In some embodiments, the large direct expansion unit further includes a filter section 25 disposed between the air inlet 11 and the evaporation section 22. The filter section 25 is used to filter the air flowing in from the air inlet 11 before it flows to the evaporation section 22. The filter section 25 includes an electrostatic precipitator for electrostatically removing dust from the air and a coarse filter 251 located upstream of the electrostatic precipitator along the air flow direction for filtering particulate matter in the air. The air entering from the air inlet 11 may contain impurities such as dust. The larger particulate matter therein is first filtered through the coarse filter 251, and then the small impurities are eliminated through electrostatic precipitator, which helps to obtain clean air for transmission to the air outlet.

[0055] In some embodiments, the large direct expansion unit is a water-cooled direct expansion unit, and the radiator is provided with pipes for introducing and discharging cooling water. The heat dissipation of the refrigerant in the radiator is achieved by heat exchange with the introduced cooling water.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the utility model can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the utility model, which should be included in the scope of the technical solution for protection of the utility model.

Claims

1. A large direct expansion unit, characterized in that: include: A box body (1) comprises an air inlet (11) and an air outlet (12) for outputting cold air; A refrigeration unit, comprising a main unit section (21) and an evaporation section (22) arranged in the housing (1), wherein the evaporation section (22) is arranged between the air inlet (11) and the air outlet (12), the main unit section (21) comprises a compressor for compressing a refrigerant and a radiator (211) for dissipating heat from the refrigerant, and the evaporation section (22) comprises an evaporator connected to the compressor and the radiator (211); The fan section (23) is arranged between the evaporation section (22) and the air outlet (12), and comprises a fan wall composed of a plurality of fans, wherein the plurality of fans comprises a plurality of fan rows (231) sequentially distributed in a horizontal direction, and each fan row (231) comprises a plurality of fans arranged in a vertical direction. When in operation, the fan wall draws air that enters the housing (1) through the air inlet (11) and undergoes heat exchange with the evaporator, and transports the air to the outside through the air outlet (12).

2. The large direct expansion unit according to claim 1, characterized in that: The multiple fans of the fan array (231) are evenly distributed in the vertical direction, and the multiple fan arrays (231) are evenly distributed in the horizontal direction.

3. The large direct expansion unit according to claim 2, characterized in that: The multiple fans constituting the fan wall are arranged in rows and columns, and the number of rows and columns of the multiple fans is the same.

4. The large direct expansion unit according to claim 1, characterized in that: It also includes a silencer section (24) disposed between the fan section (23) and the air outlet (12), and the air outputted from the fan wall is delivered to the air outlet (12) after being subjected to noise reduction by the silencer section (24).

5. The large direct expansion unit according to claim 4, characterized in that: The muffler section (24) comprises a plurality of mufflers (245) distributed in the horizontal direction and in the vertical direction, and the mufflers (245) adjacent to each other in the horizontal direction and in the vertical direction are arranged at intervals, and the muffler (245) comprises a muffler cavity, and a shell of the muffler (245) is provided with a plurality of muffler holes on a surface facing the adjacent muffler (245), and the muffler holes are connected to the muffler cavity.

6. The large direct expansion unit according to claim 5, characterized in that: The muffler section (24) comprises a first mounting frame (241) and a second mounting frame (242); the first mounting frame (241) is provided with a plurality of first closed shells (243) corresponding one-to-one to the plurality of mufflers (245); the second mounting frame (242) is provided with a plurality of second closed shells (244) corresponding one-to-one to the plurality of mufflers (245); the muffler (245) is a columnar muffler (245); the muffler (245) is arranged between the first mounting frame (241) and the second mounting frame (242); and each of the mufflers (245) is closed and connected by a first closed shell (243) and a second closed shell (244) at both ends along the axial direction; the first mounting frame (241) and the second mounting frame (242) are arranged along the flow direction of the air transported to the air outlet (12).

7. The large direct expansion unit according to claim 6, characterized in that: Along the flow direction of air passing through the silencer section (24), the first enclosed shell (243) is located upstream of the second enclosed shell (244), and the radial outer side of the outer surface of the first enclosed shell (243) facing the fan section (23) is inclined relative to the radial inner side along the flow direction of the air.

8. The large direct expansion unit according to claim 6, characterized in that: The plurality of mufflers (245) are aligned in the horizontal direction and in the vertical direction to form a plurality of vertical air flow channels arranged at intervals in the horizontal direction and a plurality of horizontal air flow channels arranged at intervals in the vertical direction between the plurality of mufflers (245).

9. The large direct expansion unit according to any one of claims 5 to 8, characterized in that: A layered sound absorbing material is also provided in the cavity of the muffler (245).

10. The large direct expansion unit according to any one of claims 5 to 8, characterized in that: The silencer (245) is a rectangular silencer (245), and the multiple silencers (245) have the same shape.

11. The large direct expansion unit according to claim 1, characterized in that: The main engine section (21) comprises an isolation cover (212) arranged in the housing (1), and the radiator (211) is arranged in the isolation cover (212). The isolation cover (212) is a closed structure to prevent the refrigerant leaking from the radiator (211) from flowing out of the isolation cover (212) and entering the air flowing in the housing (1).

12. The large direct expansion unit according to claim 11, characterized in that: The compressor is also arranged in the isolation cover (212).

13. The large direct expansion unit according to claim 11, characterized in that: It also includes a pressure relief pipe (213) passing through the isolation cover (212) and the box body (1) to discharge the refrigerant to the outside of the box body (1), and a safety valve (214) provided between the pressure relief pipe (213) and the refrigerant flow pipeline of the radiator (211), wherein the safety valve (214) is configured to open when the pressure of the refrigerant in the refrigerant flow pipeline of the radiator (211) exceeds a safety threshold value to discharge the refrigerant to the outside of the box body (1) through the pressure relief pipe (213).

14. The large direct expansion unit according to claim 1, characterized in that: The invention also comprises a filter section (25) arranged between the air inlet (11) and the evaporation section (22), wherein the filter section (25) is used to filter the air flowing in from the air inlet (11) before the air flows to the evaporation section (22), and the filter section (25) comprises an electrostatic precipitator for electrostatically removing dust from the air and a coarse filter (251) located upstream of the electrostatic precipitator along the air flow direction and used to filter particulate matter in the air.

15. The large direct expansion unit according to claim 1, characterized in that: The large direct expansion unit is a water-cooled direct expansion unit.

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