Heat exchange tube, heat exchange device, cascade unit, combined cooling and heating system and control method

Abstract

The invention relates to a heat exchange tube, a heat exchange device, a cascade unit, a cold and heat cogeneration system and a control method. The heat exchange tube comprises a tube body and a first heat exchange structure, and the tube body is internally provided with a first channel used for containing a first working medium; the multiple first heat exchange structures are arranged on the peripheral face of the pipe body and used for making contact with a second working medium for heat exchange; the first heat exchange structure comprises a heat exchange main body and a turbulent flow part which are in angular connection. The first heat exchange structure of the heat exchange tube comprises the heat exchange main body and the turbulent flow part which are in angular connection, in the process that the second working medium firstly makes contact with the heat exchange main body and flows to the peripheral face of the tube body along the heat exchange main body, part of the second working medium makes contact with the turbulent flow part, turning of the flowing direction is achieved, and heat exchange efficiency is improved. Therefore, turbulent motion is generated at the turbulent flow part, the first heat exchange structure and a flowing boundary layer outside the tube body are damaged by enhancing disturbance on the second working medium, and the heat transfer efficiency and the heat exchange effect of the heat exchange tube can be improved.

Description

Technical Field

[0001] The present application relates to the field of heat exchange technology, and in particular to a heat exchange tube, a heat exchange device, a cascade unit, a cooling and heating cogeneration system, and a control method. Background Art

[0002] In industrial production, food and medical industries, energy industry and daily life, heat exchange devices are often used to achieve heat exchange between two or more substances, thereby achieving temperature control, energy transfer, cost reduction and efficiency improvement.

[0003] As the core component of the heat exchange device, the heat exchange tube greatly affects the heat transfer efficiency and performance of the heat exchange device. Specifically, the tube wall of the heat exchange tube can be used as a heat transfer medium between two working fluids, and its material and structure will affect the heat transfer coefficient and heat transfer efficiency of the heat exchange tube.

[0004] In order to reduce manufacturing costs, the heat exchange tubes in the prior art are usually bare tubes, that is, straight tubes or curved tubes without special structures on the inner and outer surfaces of the tube body. When the working fluid flows along the surface of the bare tube, a stable flow boundary layer (also called fluid boundary layer) will be generated. When the thickness of the flow boundary layer is large, the distance for heat to be transferred from the fluid to the solid wall will be longer, the heat transfer efficiency will be lower, and the heat exchange effect of the heat exchange device will be worse. Summary of the invention

[0005] The present application provides a heat exchange tube, a heat exchange device, a cascade unit, a combined cooling and heating system and a control method to solve the technical problem in the prior art that when the heat exchange tube is a bare tube, a flow boundary layer with a stable thickness is easily generated, resulting in low heat transfer efficiency of the heat exchange tube.

[0006] In a first aspect, the present application provides a heat exchange tube, comprising:

[0007] A tube body, wherein the interior of the tube body has a first channel for accommodating a first working medium;

[0008] The first heat exchange structure, the number of the first heat exchange structures is multiple, and the multiple first heat exchange structures are arranged on the outer peripheral surface of the tube body for contacting and exchanging heat with the second working medium; the first heat exchange structure includes a heat exchange body and a spoiler connected at an angle.

[0009] Optionally, the heat exchange body is extended along the radial direction of the tube body, and the spoiler is extended along the axial direction of the tube body.

[0010] Optionally, a protrusion is provided on one side or both sides of the heat exchange body.

[0011] Optionally, a second heat exchange structure is provided on the inner circumferential surface of the tube body to increase the heat exchange area inside the first channel.

[0012] Optionally, there are multiple second heat exchange structures, and the multiple second heat exchange structures are spirally arranged on the inner circumference of the tube body to form a plurality of spiral grooves on the inner circumference of the tube body.

[0013] In a second aspect, the present application provides a heat exchange device, including the heat exchange tube provided in the first aspect of the present application, and also including a shell, the interior of the shell has a cavity for accommodating a second working medium, and the heat exchange tube is arranged inside the cavity.

[0014] Optionally, a flow equalizer is provided in the head at one end of the shell, and multiple heat exchange tubes are arranged in parallel inside the cavity. The side of the head away from the cavity has a first working fluid inlet. In the flow direction of the first working fluid, the flow equalizer is arranged at the front end of the multiple heat exchange tubes.

[0015] In the third aspect, the present application provides a cascade unit, including the heat exchange device provided in the second aspect of the present application, and also including a high-temperature stage system and a low-temperature stage system. The heat exchange device is an evaporative condenser in the cascade unit, and the heat exchange device is respectively connected to the high-temperature stage system and the low-temperature stage system.

[0016] Optionally, the refrigerant circulating in the high-temperature system is a first working fluid, and the refrigerant circulating in the low-temperature system is a second working fluid, and the first working fluid and the second working fluid are of different types.

[0017] Optionally, the first working fluid is R1233zd(E) or R245fa, and the second working fluid is R134a, R515B or R1234ze.

[0018] Optionally, the high-temperature stage system includes a first compressor, the low-temperature stage system includes a second compressor, and both the first compressor and the second compressor are provided with a compression ratio regulating valve.

[0019] In a fourth aspect, the present application provides a combined heat and cold generation system, including the cascade unit provided in the third aspect of the present application, and also including a hot fluid supply system, a steam supply system and a cold fluid supply system. The hot fluid supply system and the steam supply system are both connected to the high-temperature stage system, and heat exchange is performed through the condenser of the high-temperature stage system. The cold fluid supply system is connected to the low-temperature stage system, and heat exchange is performed through the evaporator of the low-temperature stage system.

[0020] Optionally, the steam supply system comprises a steam generator.

[0021] Optionally, the steam supply system further includes a booster pump in communication with the steam generator.

[0022] In a fifth aspect, the present application provides a control method, which is applied to the cooling and heating cogeneration system provided in the fourth aspect of the present application, and comprises the following steps:

[0023] Step 1: Obtain fluid supply requirements;

[0024] Step 2: Adjust the compression ratio of the high-temperature system and the low-temperature system according to the fluid supply demand, so that there is a first temperature difference between the refrigerant temperature in the heat exchange device and the refrigerant temperature in the evaporator of the low-temperature system, and there is a second temperature difference between the refrigerant temperature in the condenser of the high-temperature system and the refrigerant temperature in the heat exchange device.

[0025] Optionally, the fluid supply requirement includes a fluid type requirement and a fluid temperature requirement, and the fluid types include cold fluid, hot fluid and steam.

[0026] Optionally, the first temperature difference is 35°C-75°C, and the second temperature difference is 50°C-100°C.

[0027] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0028] The heat exchange tube provided in the embodiment of the present application has a first channel inside the tube body for accommodating a first working fluid, and the first working fluid can achieve heat transfer with the tube body when flowing in the first channel. A plurality of first heat exchange structures are arranged on the outer peripheral surface of the tube body, and the surface area of ​​the plurality of first heat exchange structures can be used to significantly increase the heat exchange area for contact and heat exchange with the second working medium, thereby improving the heat transfer coefficient of the heat exchange tube; the first heat exchange structure includes a heat exchange body and a spoiler connected at an angle, and in the process that the second working medium first contacts the heat exchange body and flows along the heat exchange body to the outer peripheral surface of the tube body, a part of the second working medium contacts the spoiler to realize the turning of the flow direction, thereby generating turbulent motion at the spoiler, while increasing the heat exchange area through the heat exchange body and the spoiler, by enhancing the disturbance of the second working medium to destroy the flow boundary layer of the first heat exchange structure and the outside of the tube body, the thinning of the flow boundary layer on the wall of the tube body can be realized, the shorter the distance that heat is transferred from the fluid (i.e., the second working medium) to the wall of the tube body, the higher the heat transfer efficiency, the heat exchange effect of the heat exchange tube is improved, and the heat transfer between the first working medium and the second working medium can be efficiently realized through the heat exchange tube.

[0029] The heat exchange device, cascade unit, combined heat and cold production system and control method provided in the embodiments of the present application include the above-mentioned heat exchange tubes, and efficient heat transfer between working media can be achieved through the heat exchange tubes. Therefore, they naturally have the technical effects of the above-mentioned heat exchange tubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0032] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0033] Figure 1 A partial cross-sectional view of a heat exchange tube provided in an embodiment of the present application;

[0034] Figure 2 Provided in the embodiments of this application Figure 1 A magnified view of the details of part A;

[0035] Figure 3 A schematic diagram of the structure of a heat exchange device provided in an embodiment of the present application;

[0036] Figure 4 A front view of a current equalizing member provided in an embodiment of the present application;

[0037] Figure 5 A connection diagram of a cascade unit provided in an embodiment of the present application;

[0038] Figure 6 A schematic diagram of the connection of a cooling and heating cogeneration system provided in an embodiment of the present application;

[0039] Figure 7 A schematic diagram of the connection between the high temperature system, the thermal fluid supply system and the steam supply system provided in the embodiment of the present application;

[0040] Figure 8 A schematic diagram of the connection between the cryogenic stage system and the cold fluid supply system provided in an embodiment of the present application.

[0041] Description of reference numerals:

[0042] 1. heat exchange device; 11. heat exchange tube; 111. tube body; 112. heat exchange main body; 113. flow spoiler; 114. protrusion; 115. second heat exchange structure; 116. spiral groove; 12. shell; 13. flow equalizer; 131. plate body; 132. flow equalizer hole; 133. avoidance part; 14. partition; 15. first end cap; 16. second end cap;

[0043] 2. High temperature system; 21. First compressor; 22. First throttling device; 23. First economizer; 24. Second throttling device; 25. Condenser; 26. First refrigerant circulation loop; 261. First refrigerant output pipeline; 262. Second refrigerant output pipeline;

[0044] 3. Low temperature system; 31. Second compressor; 32. Third throttling device; 33. Second economizer; 34. Fourth throttling device; 35. Evaporator; 36. Second refrigerant circulation loop; 361. Third refrigerant output pipeline; 362. Fourth refrigerant output pipeline;

[0045] 4. Hot fluid supply system; 41. First liquid replenishment pipeline; 42. First pump component; 43. Supply pipeline; 44. First valve component;

[0046] 5. Steam supply system; 51. Steam generator; 52. Booster pump; 53. Second valve component; 54. Second liquid replenishing pipeline; 55. Second pump component;

[0047] 6. Cold fluid supply system; 61. Input pipeline; 62. Outflow pipeline; 63. Third pump component. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0049] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplification and clarity, and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0050] For ease of description, spatial relative terms may be used herein to describe the relative positional relationship or movement of one element or feature relative to another element or feature as shown in the figure, such as "inside", "outside", "inner side", "outer side", "below", "below", "above", "above", "front", "back", etc. Such spatial relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure undergoes a position flip or a posture change or a motion state change, then these directional indications also change accordingly, for example: an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented as "above other elements or features" or "above other elements or features". Therefore, the example term "below..." may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions) and the spatial relative descriptors used herein are interpreted accordingly.

[0051] In order to solve the technical problem in the prior art that when the heat exchange tube is a bare tube, a flow boundary layer of stable thickness is easily generated, resulting in low heat transfer efficiency of the heat exchange tube, the present application provides a heat exchange tube 11, a heat exchange device 1, a cascade unit, a combined heat and cold production system and a control method. The heat exchange tube 11 can respectively achieve contact and heat transfer with a first working fluid and a second working fluid. A plurality of first heat exchange structures are provided on the outer peripheral surface of the tube body 111, which can be used to significantly increase the heat exchange area of ​​the tube body 111. The first heat exchange structure includes a heat exchange main body 112 and a spoiler 113. While increasing the heat exchange area through the heat exchange main body 112, the flow of the second working fluid can be disturbed through the spoiler 113, so that the fluid on the outer peripheral surface of the tube body 111 (i.e., the second working fluid) produces turbulent motion, avoids the formation of a flow boundary layer of stable thickness, and achieves thinning of the flow boundary layer, thereby increasing the heat exchange area and frequency between the second working fluid and the outer wall of the tube body 111, and improving the heat transfer performance of the heat exchange tube 11.

[0052] See also Figures 1 to 8 In a first aspect, an embodiment of the present application provides a heat exchange tube 11, comprising a tube body 111 and a plurality of first heat exchange structures. The interior of the tube body 111 has a first channel for accommodating a first working fluid. When the first working fluid flows in the first channel, heat can be transferred to the tube body 111.

[0053] Multiple first heat exchange structures are arranged on the outer peripheral surface of the tube body 111. On the basis of the area of ​​the original outer peripheral surface of the tube body 111, the heat exchange area can be greatly increased through the surface area of ​​the multiple first heat exchange structures, which are used for contact and heat exchange with the second working fluid, thereby improving the heat transfer coefficient of the heat exchange tube 11 and the heat exchange efficiency of the heat exchange tube 11, and realizing efficient heat transfer between the first working fluid and the second working fluid.

[0054] The first heat exchange structure includes a heat exchange body 112 and a spoiler 113 connected at an angle. When the second working fluid first contacts the heat exchange body 112 and flows along the heat exchange body 112 to the outer peripheral surface of the tube body 111, a part of the second working fluid contacts the spoiler 113 to realize the turning of the flow direction, thereby generating turbulent motion at the spoiler 113. While increasing the heat exchange area through the heat exchange body 112 and the spoiler 113, the flow boundary layer outside the first heat exchange structure and the tube body 111 is destroyed by enhancing the disturbance to the second working fluid, so that the flow boundary layer on the wall of the tube body 111 can be thinned, the distance for heat to be transferred from the fluid (i.e., the second working fluid) to the wall of the tube body 111 is shorter, the heat transfer efficiency is higher, the heat exchange effect of the heat exchange tube 11 is improved, and the heat transfer between the first working fluid and the second working fluid can be efficiently realized through the heat exchange tube 11.

[0055] It should be noted that the shape of the heat exchange body 112 can be a sheet, column or needle structure, and the shape of the spoiler 113 can also be a sheet, column, needle structure or pointed structure, all of which can achieve the purpose of this application.

[0056] In some embodiments of this application, please refer to Figure 1 The multiple first heat exchange structures are evenly arranged on the outer peripheral surface of the tube body 111, which can realize uniform heat conduction on the heat exchange tube 11, and can ensure that heat is more effectively transferred from one working medium to another working medium, reducing heat loss and waste. At the same time, it can also reduce the thermal stress caused by temperature difference inside the heat exchange tube 11, and reduce the risk of damage to the heat exchange tube 11 due to excessive thermal stress.

[0057] In some embodiments of this application, please refer to Figure 1 The heat exchange body 112 is arranged to extend radially along the tube body 111, which can maximize the heat exchange area while avoiding interference with other heat exchange bodies 112 adjacent to the tube body 111 in the axial direction. The spoiler 113 is arranged to extend axially along the tube body 111. When the second working medium flows along the outer wall of the heat exchange body 112 in the radial direction of the tube body 111, a part of the second working medium can achieve nearly vertical reversal through the spoiler 113, thereby generating turbulence between the two axially adjacent first heat exchange structures, enhancing disturbance, and improving the heat exchange efficiency between the second working medium and the outer wall of the tube body 111.

[0058] In some embodiments of this application, please refer to Figure 1In the axial direction of the tube body 111, the spoiler 113 is arranged on one side of the heat exchange main body 112. This is because when the spoiler 113 is arranged on both sides of the heat exchange main body 112, the axial spacing between the two adjacent first heat exchange structures is too small, which causes the temperature of the fluid (i.e., the second working fluid) accumulated between the two first heat exchange structures to be too high, thereby causing the heat transfer temperature difference between the second working fluid outside the tube body 111 and the first working fluid inside the tube body 111 to be too large, which will reduce the heat transfer effect between the two. In this application, the spoiler 113 is only arranged on one side of the heat exchange main body 112, which can not only generate turbulence between the two adjacent first heat exchange structures, but also avoid the situation where the temperature between the two adjacent first heat exchange structures is too high due to the small spacing.

[0059] In some embodiments of this application, please refer to Figure 1 and Figure 2 A protrusion 114 is provided on one or both sides of the heat exchange body 112, which can further increase the heat exchange area of ​​the first heat exchange structure, and at the same time can also have a certain disturbing effect on the fluid outside the tube body 111, thereby enhancing the heat transfer effect between the second working medium and the heat exchange tube 11.

[0060] In some embodiments of this application, please refer to Figure 1 to Figure 2 In the radial direction from the inside to the outside of the tube body 111, the cross-sectional size of the heat exchange body 112 gradually decreases, so that the distance between two adjacent heat exchange bodies 112 gradually increases. It is preferred to arrange the protrusions 114 on both sides of the free end of the heat exchange body 112 (i.e., the end away from the tube body 111), which can not only increase the heat exchange area and disturb the fluid, but also reduce the influence of the arrangement of the protrusions 114 on the distance between two adjacent first heat exchange structures.

[0061] In some embodiments of the present application, the protrusion 114 can be a sheet-shaped, block-shaped, or pointed-angled structure, all of which can achieve the purpose of the present application. The size of the protrusion 114 is smaller than the size of the spoiler 113, which can reduce the impact of the protrusion 114 on the distance between two adjacent first heat exchange structures.

[0062] In some embodiments of this application, please refer to Figure 1 The inner circumference of the tube body 111 is provided with a second heat exchange structure 115 for increasing the heat exchange area inside the first channel, thereby improving the heat transfer efficiency and heat exchange effect between the first working medium and the tube body 111.

[0063] It should be noted that the second heat exchange structure 115 can be a fin structure, a texture structure, or a groove structure disposed on the inner wall of the tube body 111 , all of which can achieve the purpose of the present application.

[0064] In some embodiments of this application, please refer to Figure 1A plurality of second heat exchange structures 115 are arranged in a spiral shape on the inner circumference of the tube body 111, and are used to form a plurality of spiral grooves 116 on the inner circumference of the tube body 111. When the first working medium flows inside the tube body 111, the flow restriction effect of the spiral grooves 116 can make the fluid in the tube do an overall spiral motion, thereby increasing the fluid disturbance. At the same time, the body resistance caused by the spiral grooves 116 can separate the flow boundary layer inside the tube body 111, thereby enhancing the heat transfer effect between the first working medium and the tube body 111.

[0065] It should be noted that the cross-section of the second heat exchange structure 115 can be in a tooth-shaped, rectangular or triangular shape, etc., which can achieve the purpose of the present application.

[0066] As a specific embodiment of the present application, the cross-section of the second heat exchange structure 115 is tooth-shaped, and the cross-section of the spiral groove 116 formed between two adjacent second heat exchange structures 115 is trapezoidal, so that the inner wall surface of the tube body 111 is uneven, which can greatly increase the heat exchange area of ​​the inner wall of the tube body 111. Part of the fluid close to the inner wall rotates along the spiral groove 116, while the other part of the fluid flows axially along the wall, so that the fluid (i.e., the first working fluid) changes from laminar flow to turbulent flow or a more violent disturbance state. This change in flow state helps to reduce the thickness of the flow boundary layer, making it easier for the fluid to contact the inner wall of the tube body 111, thereby improving the heat transfer efficiency.

[0067] See also Figures 1 to 8 A second aspect of an embodiment of the present application provides a heat exchange device 1, comprising the heat exchange tube 11 described in the above embodiment, and also comprising a shell 12, the interior of the shell 12 having a cavity for accommodating a second working fluid, the heat exchange tube 11 being arranged inside the cavity, and the first working fluid and the second working fluid are efficiently heat transferred inside the heat exchange device 1 through the heat exchange tube 11.

[0068] In some embodiments of this application, please refer to Figure 3 A flow equalizer 13 is provided in the head at one end of the shell 12, and multiple heat exchange tubes 11 are arranged in parallel inside the cavity. A first working fluid inlet is provided on the side of the head away from the cavity, which is used to input liquid first working fluid into the head. In the flow direction of the first working fluid, the flow equalizer 13 is arranged at the front end of the multiple heat exchange tubes 11. The flow equalizer 13 can optimize the flow state and mixing effect of the first working fluid inside the head, and can avoid uneven distribution of the first working fluid fluid and uneven temperature distribution among the multiple heat exchange tubes 11, thereby avoiding the deterioration of heat transfer caused by uneven liquid distribution.

[0069] It should be noted that the shape, location and number of the flow equalizer 13 can be set according to the flow conditions of the first working fluid inside the head. As long as the flow state and mixing effect of the first working fluid can be optimized, the purpose of this application can be achieved.

[0070] In some embodiments of this application, please refer to Figure 3 When the heat exchange device 1 is a horizontal shell and tube heat exchange device, a first working medium liquid inlet and a first working medium gas outlet are respectively provided on the first head 15 at one end of the shell 12. The interior of the first head 15 is divided into two independent cavities by a partition 14 to prevent the liquid first working medium and the gaseous first working medium from mixing in the first head 15. The flow equalizer 13 is arranged at the lower part of the first head 15, and the top of the flow equalizer 13 is connected to the partition 14. The first working medium inside the first head 15 is equalized by the flow equalizer 13, and the liquid first working medium is evenly distributed to the multiple heat exchange tubes 11 at the bottom of the shell 12. After the gaseous second working medium enters the shell 12, it can achieve heat exchange and condensation with the first heat exchange structure on the outer peripheral surface of the heat exchange tube 11. The multiple first heat exchange structures can slow down the flow rate of the gaseous second working medium, so as to achieve long-term contact and sufficient heat exchange between the second working medium and the heat exchange tube. The condensed second working medium falls to the bottom of the shell 12 under the action of gravity, and the liquid second working medium can be output from the bottom of the shell 12; the gaseous first working medium can realize U-shaped reflux in the second head 16, reflux to the first head 15 through the heat exchange tube 11 at the top of the shell 12, and flow out through the first working medium outlet at the top of the first head 15.

[0071] In some embodiments of this application, please refer to Figure 4 The flow equalizing member 13 includes a plate body 131 and a plurality of flow equalizing holes 132 disposed on the plate body 131. When the second working medium passes through the plurality of flow equalizing holes 132, the second working medium can be more evenly distributed and flowed in the shell 12. The upper portion of the plate body 131 has a plurality of avoidance portions 133 to avoid interference with other components (such as the partition plate 14, etc.) assembled inside the head of the shell 12.

[0072] In some embodiments of the present application, a mixed phase liquid homogenizer is further provided at the end caps at both ends of the shell 12 to further enhance the mixing effect of the first working fluid inside the shell 12 .

[0073] It should be noted that the above-mentioned heat exchange device 1 can be applied to any usage scenario that requires heat exchange, such as home life, industrial production, energy and chemical industries, etc., and can achieve efficient transfer of heat between different working fluids.

[0074] See also Figures 1 to 8In a third aspect of an embodiment of the present application, a cascade unit is provided, comprising the heat exchange device 1 described in the above embodiment, and also comprising a high-temperature stage system 2 and a low-temperature stage system 3. The heat exchange device 1 is an evaporative condenser in the cascade unit, and the heat exchange device 1 is connected to the high-temperature stage system 2 and the low-temperature stage system 3 respectively, so that the heat exchange device 1 is both an evaporating device in the high-temperature stage system 2 and a condensing device in the low-temperature stage system 3. Since the heat exchange tube 11 in the heat exchange device 1 has the advantages of high heat transfer coefficient and good heat exchange effect, it can ensure that the heat transfer between the high-temperature stage system 2 and the low-temperature stage system 3 is sufficient and efficient, which can reduce the energy loss of the cascade unit and improve the overall efficiency of the cascade unit.

[0075] In some embodiments of this application, please refer to Figure 5 The refrigerant circulating in the high-temperature system 2 is the first working medium, which can flow in the first channel inside the heat exchange tube 11, and enhance the heat exchange efficiency between the first working medium and the tube body 111 through the second heat exchange structure 115; the refrigerant circulating in the low-temperature system 3 is the second working medium, which can perform contact heat exchange with the first heat exchange structure arranged outside the heat exchange tube 11, thereby realizing heat transfer between the high-temperature system 2 and the low-temperature system 3.

[0076] Specifically, the first working medium is in liquid state before flowing into the tube body 111, and the second working medium is in gaseous state before entering the shell 12 of the heat exchange device 1. After heat conduction is achieved through the tube body 111 of the heat exchange tube 11, the second heat exchange structure 115 and the first heat exchange structure, the first working medium evaporates from liquid state to gaseous state inside the tube body 111, and the second working medium condenses from gaseous state to liquid state inside the shell 12.

[0077] In traditional heat pump systems, since conventional heat pump systems use a single refrigerant and only have one refrigeration cycle, it is not only difficult to achieve a large temperature rise (such as above 120°C) between the evaporation side and the condensation side, but also leads to a huge total compression ratio, and the compressor efficiency will be seriously reduced. For example, when the refrigerant temperature on the evaporation side is 5°C and the refrigerant temperature on the condensation side is 132°C, if R1233zd(E) is used as the refrigerant, its compression ratio can be as high as 33.32.

[0078] In order to solve the above problems, in some embodiments of the present application, the first working fluid and the second working fluid are of different types, and the evaporation temperature of the second working fluid is lower than the evaporation temperature of the first working fluid. The high temperature rise requirement can be met by two independent refrigeration systems in the cascade unit, and the compression ratio inside the single-stage refrigeration system can be reduced. For example, when the refrigerant temperature in the evaporator 35 of the low-temperature stage system 3 is 5°C and the refrigerant temperature in the condenser 25 of the high-temperature stage system 2 is 132°C, the single-stage compression ratio does not exceed 3 (that is, the compression ratio of the high-temperature stage system 2 and the compression ratio of the low-temperature stage system 3 do not exceed 3), which can improve the compressor efficiency and the system energy efficiency of the cascade unit is also improved.

[0079] In some embodiments of the present application, the first working fluid is R1233zd(E) (trans-1-chloro-3,3,3-trifluoropropene) or R245fa (pentafluoropropane); wherein, the GWP value (global warming potential) of R1233zd(E) is 1, making it a refrigerant with low global warming potential, and will not damage the ozone layer, which is in line with the trend of future environmental protection regulations; and the GWP value of R245fa is 858, but due to R245fa has high heat capacity and good evaporation characteristics The properties enable it to provide excellent refrigeration effect in a wide temperature range, and it is particularly suitable for occasions that require efficient and reliable refrigeration effects; when selecting refrigerants, from an environmental perspective, R1233zd (E) is better than R245fa, and from an energy efficiency perspective, the energy efficiency of R1233zd (E) is 5%-7% higher than that of R245fa; from a unit mass cooling capacity / heating capacity perspective, the heating capacity of R1233zd (E) is 10%-15% lower than that of R245fa. Therefore, from an environmental perspective and energy efficiency perspective, R1233zd (E) should be selected as the first working fluid, and R245fa should be selected as the first working fluid when considering cooling capacity matching, so that the high temperature system 2 can meet different usage requirements.

[0080] In some embodiments of the present application, the second working fluid is R134a (tetrafluoroethane), R515B (Honeywell R515B refrigerant) or R1234ze (1,3,3,3-tetrafluoropropylene); from the perspective of environmental protection, the ODP values ​​(ozone depletion potential) of the three are close to 0, and the GWP values ​​are arranged from large to small as R515B>R134a>R1234ze; and the GWP value of R1234ze is extremely low (less than 1), much lower than traditional refrigerants, which helps to reduce the negative impact on the environment. From the perspective of energy efficiency, the system energy efficiency of R134a is more than 16% higher than that of R515B, which is on par with R1234ze. Considering the unit mass cooling capacity / heating capacity, the unit cooling capacity of R134a is about 30% lower than that of R515 and about 25% higher than that of R1234ze. Therefore, when the highest energy efficiency is considered, R134a is used as the second working fluid; when the cooling capacity is matched and the energy efficiency requirement is not high, R515B is used as the second working fluid; from an environmental protection perspective, R1234ze is considered as the second working fluid, so that the low-temperature system 3 can meet different usage requirements.

[0081] In some embodiments of the present application, from the perspective of energy efficiency, the low-temperature system 3 should select R134a in combination with R1233zd(E) in the high-temperature system 2; from the perspective of environmental protection, the low-temperature system 3 should select R1234ze in combination with R1233zd(E) in the high-temperature system 2; only when the cooling capacity / heating capacity matching is considered and the energy efficiency requirement is not high, the low-temperature system 3 adopts R515B in combination with R245fa in the high-temperature system 2, so that the cascade unit can meet the usage requirements from different angles.

[0082] In some embodiments of this application, please refer to Figure 5 The high-temperature system 2 includes a first compressor 21, and the low-temperature system 3 includes a second compressor 31. The first compressor 21 and the second compressor 31 are both provided with a compression ratio regulating valve, which can adjust the exhaust pressure of the compressor (i.e., the first compressor 21 and the second compressor 31), and can adjust the compression ratio of the compressor according to actual needs, so that it can adapt to different working conditions and load requirements, and can be used to match the system working conditions, ensuring that the compressor can operate in the best state under different working conditions, and ensuring that the system energy efficiency is at the best.

[0083] In some preferred embodiments of the present application, the compression ratio regulating valve is specifically a compression ratio regulating slide valve, which is used to match the system operating conditions and can adjust the exhaust pressure of the compressor, thereby achieving compression ratio adjustment of the high-temperature stage system 2 and the low-temperature stage system 3 to ensure that the system energy efficiency is at its best.

[0084] In some embodiments of this application, please refer to Figure 5 The first compressor 21 and the second compressor 31 are both two-stage variable frequency variable pressure ratio screw compressors, which can reduce the compression ratio of a single machine through two-stage compression, achieve reasonable pressure distribution, reduce the force on the rotor and bearings, make the operation of the compressor more stable, and have the advantages of high efficiency and energy saving, stable operation, low noise and vibration, low maintenance cost and strong applicability. In addition, since the first compressor 21 and the second compressor 31 both have a variable frequency function, the speed can be changed by adjusting the variable frequency motor of the compressor, thereby realizing the adjustment of the exhaust volume of the compressor.

[0085] In some embodiments of this application, please refer to Figure 5The high temperature stage system 2 also includes a first throttling device 22, a first economizer 23, a second throttling device 24, a condenser 25 and a first refrigerant circulation loop 26. The first throttling device 22, the first economizer 23, the second throttling device 24 and the condenser 25 are all arranged on the first refrigerant circulation loop 26. Both ends of the heat exchange device 1 are respectively connected to the first refrigerant circulation loop 26 for transporting the first working medium to the inside of the heat exchange tube 11 of the heat exchange device 1. After being discharged from the first compressor 21, the first working fluid enters the condenser 25 and is condensed into a liquid first working fluid, and then throttled and depressurized by the first throttling device 22. After throttling and depressurization, the first working fluid enters the first economizer 23. The first economizer 23 is a first flash evaporator, which can realize rapid expansion and partial vaporization of the first working fluid. Part of the gaseous first working fluid is input into the air inlet of the first compressor 21 through the first refrigerant output pipeline 261 for air replenishment, and the other part of the liquid first working fluid flows through the second throttling device 24 and the heat exchange device 1 in sequence through the second refrigerant output pipeline 262, and is evaporated and vaporized in the heat exchange device 1 and then sucked into the first compressor 21, thereby realizing the refrigerant circulation of the high-temperature system 2.

[0086] In some embodiments of the present application, the low-temperature stage system 3 also includes a third throttling device 32, a second economizer 33, a fourth throttling device 34, an evaporator 35 and a second refrigerant circulation loop 36; the third throttling device 32, the second economizer 33, the fourth throttling device 34, and the evaporator 35 are all arranged on the second refrigerant circulation loop 36, and the two ends of the heat exchange device 1 are respectively connected to the second refrigerant circulation loop 36, for transporting the second working medium to the inside of the shell 12 of the heat exchange device 1. After being discharged from the second compressor 31, the second working fluid enters the heat exchange device 1 and is condensed into the liquid first working fluid, and then passes through the third throttling device 32 to achieve throttling and pressure reduction. After throttling and pressure reduction, the second working fluid enters the second economizer 33. The second economizer 33 is a second flash evaporator, which can realize rapid expansion and partial vaporization of the second working fluid. Part of the gaseous second working fluid is input into the air inlet of the second compressor 31 through the third refrigerant output pipeline 361 for air replenishment, and the other part of the liquid second working fluid flows through the fourth throttling device 34 and the evaporator 35 in sequence through the fourth refrigerant output pipeline 362, and is evaporated and vaporized in the evaporator 35 and then sucked into the second compressor 31, thereby realizing the refrigerant circulation of the low-temperature system 3.

[0087] It should be noted that in the above-mentioned cascade unit, a temperature rise of more than 100 degrees Celsius can be achieved between the evaporator 35 of the low-temperature stage system 3 and the condenser 25 of the high-temperature stage system 2, and the single-stage compression ratio does not exceed 3. By optimizing the selection and circulation process of the refrigerant, a higher energy efficiency ratio can be achieved and energy consumption can be reduced.

[0088] See also Figures 1 to 8The fourth aspect of the embodiment of the present application provides a combined heat and cold production system, including the cascade unit described in the above embodiment, and also including a hot fluid supply system 4, a steam supply system 5 and a cold fluid supply system 6. The hot fluid supply system 4 and the steam supply system 5 are both connected to the high-temperature stage system 2, and heat exchange is performed through the condenser 25 of the high-temperature stage system 2. The industrial waste heat of the cascade unit can be used to produce high-temperature hot fluid or high-temperature steam, thereby realizing the transfer and reuse of energy.

[0089] The cold fluid supply system 6 is connected to the low temperature system 3, and heat is exchanged through the evaporator 35 of the low temperature system 3. The cold fluid can be cooled (i.e., cooled) by absorbing the waste heat of the cold fluid supply system 6, and the energy can be transferred and reused.

[0090] It should be noted that the cascade unit can reduce energy waste and emissions in the process of combined cooling and heating. Traditional cooling and heating systems often operate separately, with low energy utilization efficiency and prone to generate a large amount of waste heat and emissions. The combined cooling and heating system combines the cooling and heating processes through the cascade unit, realizing the recycling and efficient use of energy, thereby reducing energy consumption and emissions.

[0091] It should be noted that the hot fluid supply system 4 can be used to supply any high-temperature (i.e., temperature above 60°C) liquid fluid substance, the steam supply system 5 can be used to supply any fluid substance that evaporates into a gaseous state, and the cold fluid supply system 6 can be used to supply any low-temperature (temperature below 20°C) liquid fluid substance. The above-mentioned liquid fluid substances can specifically be water, oil, solutions, etc., and the fluid substances that evaporate into a gaseous state can be water vapor or steam generated by the evaporation of other liquid substances, which is not limited here.

[0092] In some embodiments of the present application, when the components of the supplied materials in the thermal fluid supply system 4 and the steam supply system 5 are different, heat exchange with the condenser 25 can be performed through two independent pipelines, thereby realizing the supply of thermal fluid and steam respectively.

[0093] In some embodiments of this application, please refer to Figure 6 and Figure 7 When the supply material components in the hot fluid supply system 4 and the steam supply system 5 are the same, both are the first heat exchange working fluid, they can share the same heat exchange pipeline to input the first heat exchange working fluid into the high-temperature condenser 25, realize heat exchange with the first working fluid in the condenser 25, thereby realizing the temperature increase of the first heat exchange working fluid.

[0094] In some embodiments of this application, please refer to Figure 6 and Figure 7The hot fluid supply system includes a first liquid replenishing pipeline 41 connected to the condenser 25. The first liquid replenishing pipeline 41 is provided with a first pump 42, which can be used to drive the first heat exchange medium to flow.

[0095] In some embodiments of this application, please refer to Figure 6 and Figure 7 The steam supply system 5 includes a second liquid replenishing pipeline 54 connected to the condenser 25 . The second liquid replenishing pipeline 54 is provided with a second pump 55 for driving the first heat exchange medium for generating steam into the heat exchange pipeline of the condenser 25 .

[0096] In some embodiments of this application, please refer to Figure 6 and Figure 7 The hot fluid supply system 4 includes a first valve component 44, and the steam supply system 5 includes a second valve component 53. When the first heat exchange medium with a raised temperature flows out of the condenser 25, the flow direction of the first heat exchange medium can be controlled by the first valve component 44 and the second valve component 53 so that the first heat exchange medium enters the supply pipeline 43 of the hot fluid supply system 4 and / or the steam supply system 5 as needed.

[0097] In some embodiments of this application, please refer to Figure 6 and Figure 7 The steam supply system 5 includes a steam generator 51. When the first heat exchange medium is not completely vaporized in the condenser 25, the steam generator 51 can be used to further generate and transport steam.

[0098] In some embodiments of this application, please refer to Figure 6 and Figure 7 The steam generator 51 is connected to the second liquid replenishing pipeline 54, which can be used to store the first heat exchange medium. The steam generator 51 has a vapor-liquid separation function, which can separate the liquid first heat exchange medium from the gaseous first heat exchange medium (i.e., steam), thereby ensuring the quality and stability of the steam output from the steam generator 51.

[0099] In some embodiments of this application, please refer to Figure 6 and Figure 7 The steam supply system 5 also includes a booster pump 52 connected to the steam generator 51, which can be used to pressurize the first heat exchange medium so that the first heat exchange medium can evaporate after reaching the required temperature in the condenser 25 and / or the steam generator 51.

[0100] In some embodiments of this application, please refer to Figure 6 and Figure 7 The boost pump 52 is disposed on the second liquid replenishing pipeline 54 , and can pressurize the first heat exchange medium before the first heat exchange medium enters the condenser 25 .

[0101] It should be noted that, when only hot fluid supply is required, the first valve member 44 is opened, the second valve member 53 is closed, and the first pump member 42 is running; when only steam is required, the first valve member 44 and the first pump member 42 are closed, the second valve member 53 and the second pump member 55 are opened, and the steam generator 51 and the booster pump 52 both operate normally to achieve steam generation and supply.

[0102] In some embodiments of this application, please refer to Figure 6 and Figure 8 The cold fluid supply system 6 includes an input pipeline 61, an outflow pipeline 62 and a third pump 63. The input pipeline 61 and the outflow pipeline 62 are connected to both ends of the low-temperature system 3, and are used to input the second heat exchange medium into the evaporator 35, so that the second heat exchange medium and the second working medium can realize heat exchange inside the evaporator 35. During the heat exchange process, the temperature of the second heat exchange medium drops and flows out from the outflow pipeline 62, thereby realizing the supply of cold fluid.

[0103] In some embodiments of the present application, the hot fluid supply system 4 is used to achieve hot water supply below 100°C, the steam supply system 5 is used to achieve steam supply above 100°C, and the cold fluid supply system 6 is used to achieve chilled water supply. When the supply temperature of the chilled water is below 0°C, ethylene glycol can be added to the chilled water to prevent freezing.

[0104] See also Figures 1 to 8 The fifth aspect of the embodiment of the present application provides a control method, which is applied to the combined cooling and heating system described in the above embodiment to optimize the system energy efficiency, including the following steps:

[0105] Step 1: Obtain fluid supply requirements;

[0106] Fluid supply requirements include fluid type requirements and fluid temperature requirements. Fluid types include cold fluid, hot fluid and steam. The supply of different types of fluids can be achieved through a cold and hot cogeneration system. Specifically, the cold fluid can be chilled water, the hot fluid can be hot water, and the steam can be water vapor. When the difference in fluid temperature demand between the cold fluid and the hot fluid, or between the cold fluid and the steam is large (for example, the demand temperature of chilled water is below 7°C, while the demand temperature of steam is above 130°C, and the difference in fluid temperature demand is above 120°C), the difference in the temperature of the second working fluid in the evaporator 35 of the low-temperature system 3 and the temperature of the first working fluid in the condenser 25 of the high-temperature system 2 is also large, and the compression ratio of the first compressor 21 and the second compressor 31 can be controlled by the compression ratio regulating valve, so that the low-temperature evaporation temperature and the high-temperature condensation temperature meet the fluid temperature demand (i.e., the chilled water temperature demand, the hot water temperature demand, and the steam temperature demand, etc.). When the compression ratios of the high-temperature system 2 and the low-temperature system 3 are both close to the theoretically calculated maximum compression ratio of the system energy efficiency, the evaporation and condensation temperature of the heat exchange device 1 (i.e., the evaporative condenser) (i.e., the temperature of the first working fluid and the second working fluid in the heat exchange device 1) can be maintained within a reasonable range, which can further ensure that the compression ratio and energy efficiency of the system are in the best state.

[0107] Step 2: Adjust the compression ratio of the high-temperature system 2 and the low-temperature system 3 according to the fluid supply demand, so that there is a first temperature difference between the refrigerant temperature in the heat exchange device 1 and the refrigerant temperature in the evaporator 35 of the low-temperature system 3, and there is a second temperature difference between the refrigerant temperature in the condenser 25 of the high-temperature system 2 and the refrigerant temperature in the heat exchange device 1.

[0108] In some embodiments of the present application, the exhaust pressure and compression ratio of the first compressor 21 and the second compressor 31 can be adjusted by a compression ratio regulating valve, and the compressor exhaust volume can be adjusted by the frequency conversion function of the compressor, thereby achieving the adjustment of the evaporation and condensation temperature of the heat exchange device 1 (that is, the refrigerant temperature in the heat exchange device 1).

[0109] As a specific embodiment of the present application, when the low-temperature system 3 uses R134a as the second working fluid and the high-temperature system 2 uses R1233zd (E) as the first working fluid, the exhaust volume of the second compressor 31 in the low-temperature system 3 is Q1, and the exhaust volume of the first compressor 21 in the high-temperature system 2 is Q2. The enthalpy difference of the second working fluid of the low-temperature system 3 passing through the evaporative condenser (i.e., the heat exchange device 1) is h1, and the enthalpy difference of the first working fluid of the high-temperature system 2 passing through the evaporative condenser is h2. According to the law of conservation of energy, the evaporation heat E2 (E2 = Q2*h2) of the high-temperature refrigerant (i.e., the first working fluid) in the evaporative condenser should be equal to the condensation heat E1 (E1 = Q1*h1) of the low-temperature refrigerant (i.e., the second working fluid) in the evaporative condenser, and the enthalpy difference is only related to the evaporative condensation temperature (i.e., the refrigerant temperature in the heat exchange device 1). Therefore, when the exhaust volumes of the first compressor 21 and the second compressor 31 are confirmed, the enthalpy differences h1 and h2 are confirmed, and thus the evaporation and condensation temperatures are confirmed.

[0110] Since the refrigerant temperature in the evaporator 35 of the low-temperature system 3 is related to the temperature requirement of the cold fluid, the refrigerant temperature in the condenser 25 of the high-temperature system 2 is related to the temperature requirement of the hot fluid or steam, and the refrigerant temperature in the evaporator 35 of the low-temperature system 3, the evaporation-condensation temperature and the refrigerant temperature in the condenser 25 of the high-temperature system 2 increase successively, when the evaporation-condensation temperature is within a reasonable range, it is possible to avoid a situation where the first temperature difference and the second temperature difference are too large, thereby avoiding the compression ratio of the low-temperature system 3 and / or the compression ratio of the high-temperature system 2 being too high, thereby affecting the system energy efficiency.

[0111] In some embodiments of the present application, the hot fluid supply system 4 is used to supply hot water, the steam supply system 5 is used to supply water vapor, and the cold fluid supply system 6 is used to supply chilled water; the first temperature difference = evaporation-condensation temperature - refrigerant temperature in the evaporator 35 of the low-temperature stage system 3, the second temperature difference = refrigerant temperature in the condenser 25 of the high-temperature stage system 2 - evaporation-condensation temperature, when the evaporation-condensation temperature is in the range of 40-80°C, in order to meet the supply needs of chilled water, hot water and steam, the first temperature difference is 35°C-75°C, which can achieve -30°C-45°C chilled water supply; the second temperature difference is 50°C-100°C, which can achieve 90°C-180°C hot water or steam supply, which can meet the low-temperature cooling demand and high-temperature heating demand that are commonly present in industrial production.

[0112] In some preferred embodiments of the present application, the evaporation-condensation temperature ranges from 50° C. to 70° C., which can maximize the energy efficiency of the system.

[0113] As a specific embodiment of the present application, when the refrigerant temperature in the evaporator 35 of the low-temperature stage system 3 is 5°C and the refrigerant temperature in the condenser 25 of the high-temperature stage system 2 is 132°C, the first temperature difference is 45-65°C, which can prevent the compression ratio of the low-temperature stage system 3 from being too high, which is beneficial to ensuring the energy efficiency of the low-temperature stage system 3; the second temperature difference is 62°C-82°C, which can prevent the compression ratio of the high-temperature stage system 2 from being too high, which is beneficial to ensuring the energy efficiency of the high-temperature stage system 2, and further ensuring the energy efficiency of the entire combined cooling and heating system.

[0114] In some embodiments of the present application, when the system load changes, the compressor speed can be adjusted by the frequency conversion function of the first compressor 21 and the second compressor 31 to match the cooling capacity or heating capacity load demand; when both the system operating conditions and the load change, the compressor speed can be adjusted to match the load first, and then the compression ratio can be adjusted by the compression ratio regulating valve to maximize the system energy efficiency.

[0115] It should be understood that the terms used herein are only for the purpose of describing specific example embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "include", "comprise", "contain", and "have" are inclusive, and therefore specify the existence of stated features, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not interpreted as necessarily requiring them to be performed in the specific order described or illustrated, unless the execution order is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0116] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0117] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A heat exchange tube (11), characterized in that: include: A tube body (111), wherein the interior of the tube body (111) has a first channel for accommodating a first working medium; A first heat exchange structure, wherein the number of the first heat exchange structures is multiple, and the multiple first heat exchange structures are arranged on the outer peripheral surface of the tube body (111) for contacting and exchanging heat with the second working medium; the first heat exchange structure comprises a heat exchange body (112) and a spoiler (113) connected at an angle.

2. The heat exchange tube (11) according to claim 1, characterized in that: The heat exchange body (112) is arranged to extend in the radial direction of the tube body (111), and the spoiler (113) is arranged to extend in the axial direction of the tube body (111).

3. The heat exchange tube (11) according to claim 1, characterized in that: A protrusion (114) is provided on one or both sides of the heat exchange body (112).

4. The heat exchange tube (11) according to any one of claims 1 to 3, characterized in that: The inner circumferential surface of the tube body (111) is provided with a second heat exchange structure (115) for increasing the heat exchange area inside the first channel.

5. The heat exchange tube (11) according to claim 4, characterized in that: The number of the second heat exchange structures (115) is multiple, and the multiple second heat exchange structures (115) are arranged in a spiral shape on the inner circumference of the tube body (111) to form a plurality of spiral grooves (116) on the inner circumference of the tube body (111).

6. A heat exchange device (1), characterized in that: It comprises the heat exchange tube (11) according to any one of claims 1 to 5, and also comprises a shell (12), the shell (12) has a cavity inside for accommodating the second working medium, and the heat exchange tube (11) is arranged inside the cavity.

7. The heat exchange device (1) according to claim 6, characterized in that: A flow equalizing member (13) is provided in a sealing head at one end of the shell (12); a plurality of heat exchange tubes (11) are arranged in parallel inside the cavity; a first working fluid inlet is provided on a side of the sealing head away from the cavity; and the flow equalizing member (13) is arranged at the front end of the plurality of heat exchange tubes (11) in the flow direction of the first working fluid.

8. A cascade unit, characterized in that: It comprises the heat exchange device (1) as claimed in claim 6 or 7, and also comprises a high-temperature stage system (2) and a low-temperature stage system (3), wherein the heat exchange device (1) is an evaporative condenser in the cascade unit, and the heat exchange device (1) is connected to the high-temperature stage system (2) and the low-temperature stage system (3), respectively.

9. The cascade unit according to claim 8, characterized in that: The refrigerant circulating in the high-temperature system (2) is the first working fluid, and the refrigerant circulating in the low-temperature system (3) is the second working fluid. The first working fluid and the second working fluid are of different types.

10. The cascade unit according to claim 9, characterized in that: The first working fluid is R1233zd(E) or R245fa, and the second working fluid is R134a, R515B or R1234ze.

11. The cascade unit according to any one of claims 8 to 10, characterized in that: The high-temperature system (2) comprises a first compressor (21), and the low-temperature system (3) comprises a second compressor (31). Both the first compressor (21) and the second compressor (31) are provided with a compression ratio regulating valve.

12. A cooling and heating cogeneration system, characterized in that: It comprises a cascade unit as claimed in any one of claims 8 to 11, and also comprises a hot fluid supply system (4), a steam supply system (5) and a cold fluid supply system (6), wherein the hot fluid supply system (4) and the steam supply system (5) are both connected to the high-temperature stage system (2) and heat exchange is performed through the condenser (25) of the high-temperature stage system (2), and the cold fluid supply system (6) is connected to the low-temperature stage system (3) and heat exchange is performed through the evaporator (35) of the low-temperature stage system (3).

13. The cooling and heating cogeneration system according to claim 12, characterized in that: The steam supply system (5) comprises a steam generator (51).

14. The cooling and heating cogeneration system according to claim 13, characterized in that: The steam supply system (5) further comprises a booster pump (52) connected to the steam generator (51).

15. A control method, characterized in that: The method is applied to the cooling and heating cogeneration system as claimed in any one of claims 12 to 14, comprising the following steps: Step 1: Obtain fluid supply requirements; Step 2: Adjust the compression ratio of the high-temperature system (2) and the low-temperature system (3) according to the fluid supply demand, so that there is a first temperature difference between the refrigerant temperature in the heat exchange device (1) and the refrigerant temperature in the evaporator (35) of the low-temperature system (3), and there is a second temperature difference between the refrigerant temperature in the condenser (25) of the high-temperature system (2) and the refrigerant temperature in the heat exchange device (1).

16. The control method according to claim 15, characterized in that: The fluid supply requirements include fluid type requirements and fluid temperature requirements, and the fluid types include cold fluid, hot fluid and steam.

17. The control method according to claim 15 or 16, characterized in that: The first temperature difference is 35°C-75°C, and the second temperature difference is 50°C-100°C.

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