Variable-pipe-diameter high-efficiency finned heat exchanger

Abstract

The application discloses a variable-pipe-diameter high-efficiency finned heat exchanger, which comprises large-pipe-diameter heat exchange pipes and small-pipe-diameter heat exchange pipes connected in sequence. In the process of mixed-state refrigerant, the large-pipe-diameter heat exchange pipes are adopted; in the process of gaseous refrigerant, the small-pipe-diameter heat exchange pipes are adopted, and the pipe diameter of the large-pipe-diameter heat exchange pipes is larger than that of the small-pipe-diameter heat exchange pipes. The variable-pipe-diameter high-efficiency finned heat exchanger can increase the heat exchange efficiency of refrigerants in different states, thereby improving the overall heat exchange efficiency and heat exchange capacity.

Description

Technical Field

[0001] This invention relates to a variable diameter high-efficiency finned heat exchanger, belonging to the field of heat exchange technology. Background Technology

[0002] A heat exchanger is a device that transfers heat from one heat transfer medium to another, such as... Figure 1 As shown, the finned heat exchanger in the indoor unit of a conventional direct expansion chiller uses a heat exchange pipeline of 100, with only one pipe diameter used throughout the entire process. Before operation, in the first 3 / 4 of the process, heat exchange occurs through a two-phase refrigerant (generally 25%–30% gaseous), resulting in high heat exchange efficiency. However, in the final 1 / 4 of the process, the gaseous refrigerant absorbs heat and transforms into a superheated gaseous refrigerant, leading to lower heat exchange efficiency. Therefore, increasing the heat exchange area is necessary to improve heat exchange efficiency.

[0003] Chinese utility model patent number ZL 202122617760.5 discloses a finned heat exchanger, including two or more sets of heat exchange copper tubes with the same layout and matching heat exchange fins. The heat exchange copper tubes are arranged in parallel horizontally, and at the end face, they are arranged in a stepped manner from the left side to the right side horizontally, and vertically upwards.

[0004] Although the stepped staggered structure used in the above-mentioned finned heat exchanger can increase the heat exchange area, such a structural design is only suitable for improving the heat exchange efficiency of gaseous or mixed refrigerants, and cannot simultaneously improve the heat exchange efficiency of both mixed and gaseous refrigerants. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-efficiency finned heat exchanger with variable tube diameter.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0007] A variable-diameter high-efficiency finned heat exchanger includes large-diameter heat exchange tubes and small-diameter heat exchange tubes connected in sequence; wherein...

[0008] In processes involving mixed-state refrigerants, large-diameter heat exchange tubes are used; in processes involving gaseous refrigerants, small-diameter heat exchange tubes are used.

[0009] The diameter of the large-diameter heat exchange tube is larger than that of the small-diameter heat exchange tube.

[0010] Preferably, the large-diameter heat exchange tube and the small-diameter heat exchange tube are connected at the interface between the mixed refrigerant and the gaseous refrigerant.

[0011] Preferably, the large-diameter heat exchange tube is an internally threaded tube; the small-diameter heat exchange tube is a smooth tube.

[0012] Preferably, the number of small-diameter heat exchange tubes is twice that of large-diameter heat exchange tubes, and the small-diameter heat exchange tubes are connected to the large-diameter heat exchange tubes through connecting pipes.

[0013] Preferably, the large-diameter heat exchange tube and the small-diameter heat exchange tube are made of different metal materials.

[0014] Preferably, the thermal conductivity of the material of the large-diameter heat exchange tube is lower than that of the material of the small-diameter heat exchange tube.

[0015] Preferably, the boundary region between the mixed refrigerant and the gaseous refrigerant is determined by using simulated heat exchange results, based on the air intake conditions, air volume, refrigerant parameters, and heat exchange tube structure.

[0016] Preferably, the variable-diameter high-efficiency finned heat exchanger further includes a shell, a large-diameter heat exchange tube assembly, a small-diameter heat exchange tube assembly, and connecting pipes; wherein...

[0017] The sidewall of the housing is provided with large and small tube holes;

[0018] The large-diameter heat exchange tube group and the small-diameter heat exchange tube group are located inside the shell. The large-diameter heat exchange tube group includes multiple rows of large-diameter heat exchange tubes, and the small-diameter heat exchange tube group includes multiple rows of small-diameter heat exchange tubes. The two ends of the large-diameter heat exchange tubes and the small-diameter heat exchange tubes pass through the shell through large tube holes and small tube holes, respectively.

[0019] One end of the connecting pipe is connected to a large-diameter heat exchange tube, and the other end is connected to a small-diameter heat exchange tube.

[0020] Preferably, the variable-diameter high-efficiency finned heat exchanger further includes large-diameter U-shaped tubes and small-diameter U-shaped tubes; wherein...

[0021] The large-diameter U-shaped tube is connected between the open ends on the same side of two adjacent large-diameter heat exchange tubes.

[0022] The small-diameter U-shaped tube is connected between the open ends on the same side of two adjacent small-diameter heat exchange tubes.

[0023] Preferably, in the cooling mode, the process of the mixed refrigerant is located upstream of the boundary region, and the process of the gaseous refrigerant is located downstream of the boundary region;

[0024] In heating mode, the gaseous refrigerant flows upstream of the interface region, while the mixed refrigerant flows downstream of the interface region.

[0025] Compared with existing technologies, this invention has the following technical advantages: It employs variable-diameter heat exchange tubes and distinguishes between smooth tubes and internally threaded tubes. This ensures that, regardless of whether it's cooling or heating mode, in the mixed refrigerant flow, the larger tube diameter results in a higher proportion of liquid refrigerant and a lower flow velocity. Therefore, internally threaded tubes are used to increase turbulence and heat exchange. In the gaseous refrigerant flow, the larger proportion of gaseous refrigerant and a higher flow velocity result in greater turbulence. Therefore, smooth tubes are used to reduce resistance, while the increased number of small-diameter tubes increases the heat exchange area. This improves the overall heat exchange efficiency and heat transfer capacity of the heat exchanger, allowing both the mixed and gaseous refrigerants on both sides of the interface to achieve high heat exchange efficiency and heat transfer capacity. Through enthalpy difference chamber experiments, a double-tube finned heat exchanger of the same external dimensions showed a 5% increase in cooling capacity when used as an evaporator and a 6% increase in heating capacity when used as a condenser. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the heat exchanger tube connections in a conventional heat exchanger.

[0027] Figure 2 A schematic diagram of the heat exchange tube connection in the variable diameter high-efficiency finned heat exchanger provided by the present invention;

[0028] Figure 3 A schematic diagram of the overall structure of the variable diameter high-efficiency finned heat exchanger provided by the present invention.

[0029] Figure 4 A front view of the variable diameter high-efficiency finned heat exchanger provided by the present invention;

[0030] Figure 5 This is a schematic diagram of the structure of a Y-shaped tee pipe in an embodiment of the present invention. Detailed Implementation

[0031] The technical content of the present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0032] First Embodiment

[0033] Combination Figures 2 to 4 As shown, the first embodiment of the present invention discloses a variable diameter high-efficiency finned heat exchanger, which includes a shell 1, a large-diameter heat exchange tube group 2, a small-diameter heat exchange tube group 3, a large-diameter U-shaped tube 4, a small-diameter U-shaped tube 5, a connecting pipe 6, a straight pipe 7, an inlet pipe 8, and an outlet pipe 9. In this embodiment, a Y-type tee pipe is used as an example for the connecting pipe, but this does not constitute a limitation of the present invention.

[0034] The shell 1 is a closed shell, which is rectangular in this embodiment. Large tube holes 11 and small tube holes 12 are symmetrically opened on opposite side walls.

[0035] The large-diameter heat exchange tube group 2 and the small-diameter heat exchange tube group 3 are located inside the shell 1. In this embodiment, the large-diameter heat exchange tube group 2 includes 4 rows of large-diameter heat exchange tubes 21 (the tube diameter is 9.52 mm, or other values, such as 10.52 mm or 8.52 mm, etc.), and the small-diameter heat exchange tube group 3 includes 4 rows of small-diameter heat exchange tubes 31 (the tube diameter is 7 mm, or other values, such as 8 mm or 6 mm, etc.). The two ends of the large-diameter heat exchange tubes 21 and the small-diameter heat exchange tubes 31 pass through the shell 1 through the large tube hole 11 and the small tube hole 12, respectively.

[0036] Those skilled in the art will understand that the number and diameter of the large-diameter heat exchange tubes 21 and the small-diameter heat exchange tubes 31 do not constitute a limitation on the present invention, and the number of rows and the diameter of the large-diameter heat exchange tubes 21 and the small-diameter heat exchange tubes 31 can be changed according to different environmental conditions.

[0037] In one embodiment of the present invention, large-diameter heat exchange tubes 21 and small-diameter heat exchange tubes 31 are arranged in a cross pattern, so that each heat exchange tube can contact the air, there are no dead corners, and the arrangement density is high, thus achieving sufficient heat exchange. The large-diameter heat exchange tube group 2 is located near the air inlet of the shell 1, and one end of the row of large-diameter heat exchange tubes 21 closest to the air inlet is the inlet pipe 8. The small-diameter heat exchange tube group 3 is located near the air outlet of the shell 1, and one end of the row of small-diameter heat exchange tubes 31 closest to the air outlet (on the same side as the inlet pipe 8) is connected to the outlet pipe 9.

[0038] In this way, the large-diameter heat exchange tube is connected to the inlet pipe to receive the mixture of gaseous and liquid refrigerant from the inlet pipe. The small-diameter heat exchange tube is connected to the outlet pipe to discharge the gaseous refrigerant. In other words, the large-diameter heat exchange tube contains a mixture of gaseous and liquid refrigerant, while the small-diameter heat exchange tube contains gaseous refrigerant.

[0039] A large-diameter U-shaped tube 4 is connected between the open ends on the same side of two adjacent large-diameter heat exchange tubes 21, so that the two large-diameter heat exchange tubes 21 are connected and the flow direction of the refrigerant in the large-diameter heat exchange tubes 21 is reversed; a small-diameter U-shaped tube 5 is connected between the open ends on the same side of two adjacent small-diameter heat exchange tubes 31, so that the two small-diameter heat exchange tubes 31 are connected and the flow direction of the refrigerant in the small-diameter heat exchange tubes 31 is reversed.

[0040] like Figure 5As shown, one end of the Y-shaped tee pipe 6 is a large-diameter heat exchange tube 61, and the other end has two small-diameter heat exchange tubes 62, used to divert the refrigerant in one large-diameter heat exchange tube 21 to two small-diameter heat exchange tubes 31. The number of small-diameter heat exchange tubes 31 is twice the number of large-diameter heat exchange tubes 21, greatly increasing the heat exchange area. It should be noted that adjacent large-diameter heat exchange tubes 21 and small-diameter heat exchange tubes 31 are connected by a straight pipe 7, a large-diameter U-shaped pipe 4, and the Y-shaped tee pipe 6. The length of the straight pipe 7 is the same as the height of the Y-shaped tee pipe 6. In this way, the straight pipe 7 increases the height of the large-diameter U-shaped pipe 4 (the distance to the sidewall), so that the section from one end of the large-diameter U-shaped pipe 4 to the sidewall is the straight pipe 7, and the section from the other end to the sidewall is the Y-shaped tee pipe 6. It can be understood that the straight pipe 7 can also be omitted.

[0041] Those skilled in the art will understand that the foregoing description utilizes Y-shaped tees to achieve a ratio of two small-diameter heat exchange tubes to large-diameter heat exchange tubes; under specific circumstances, the number of small-diameter heat exchange tubes can also be three times that of large-diameter heat exchange tubes, in which case the small-diameter heat exchange tubes are connected to the large-diameter heat exchange tubes via four-way tees. Theoretically, the ratio of small-diameter heat exchange tubes to large-diameter heat exchange tubes is not limited and can be arbitrarily designed as needed.

[0042] One end of the straight tube 7 is connected to the large-diameter heat exchange tube 21, and the other end is connected to the large-diameter U-shaped tube 4. The large-diameter heat exchange tube 61 of the Y-shaped tee tube 6 is connected to the large-diameter U-shaped tube 4. The two small-diameter heat exchange tubes 62 are connected to two adjacent small-diameter heat exchange tubes 31 in the same row. The fin hole spacing of the large-diameter heat exchange tube 21 and the small-diameter heat exchange tube 31 has a specific proportional relationship, so that heat exchangers with different heights and hole numbers can meet the design of variable diameter heat exchangers.

[0043] To ensure high heat exchange efficiency in both the gas-liquid refrigerant and gaseous refrigerant pipelines, a large-diameter heat exchange tube 21 is used in the gas-liquid refrigerant pipeline (near the inlet pipe 8); a small-diameter heat exchange tube 31 is used in the gaseous refrigerant pipeline (near the outlet pipe 9). A Y-shaped tee pipe 6 connects the gas-liquid refrigerant pipeline and the gaseous refrigerant pipeline.

[0044] Since different refrigerants vaporize from liquid refrigerant to gaseous refrigerant at different temperatures, the connection point (boundary area) between the pipeline containing the gas-liquid mixture and the pipeline containing the gaseous refrigerant needs to be designed based on factors such as the operating conditions of the heat exchanger's air intake, air volume, refrigerant parameters, and the structure of the evaporator.

[0045] Specifically, using evaporator selection software, based on the inlet air conditions, air volume, refrigerant parameters, and evaporator structure, simulated heat exchange results can be obtained. These results reveal the distribution ratio of the two-phase refrigerant (mixed state) and superheated vapor refrigerant (gaseous state) within the heat exchanger, allowing determination of at which stage the variable-diameter heat exchanger begins to change pipe diameter. In other words, based on the simulated heat exchange results, the location of the boundary region between the mixed and gaseous refrigerants is identified. This boundary region is then used to determine the connection points of heat exchange tubes with different diameters within the variable-diameter heat exchanger.

[0046] The large-diameter heat exchanger tube 21 is an internally threaded copper tube with a diameter of D1 (e.g., Φ9.52 mm). The small-diameter heat exchanger tube 31 is a smooth copper tube (plain tube) with a diameter of D2 (e.g., Φ7 mm). The heat exchanger is designed such that, in cooling mode, the large-diameter heat exchanger tube 21 is connected to the refrigerant inlet and the small-diameter heat exchanger tube 31 is connected to the refrigerant outlet; in heating mode, the small-diameter heat exchanger tube 31 is connected to the refrigerant inlet and the large-diameter heat exchanger tube 21 is connected to the refrigerant outlet. That is, in both modes, the refrigerant flows in opposite directions within the heat exchanger.

[0047] As is well known, in cooling mode (mixed refrigerant from...) Figure 2 In the heat exchanger assembly 2 (where the large-diameter heat exchanger tubes 2 flow in and the gaseous refrigerant flows out from the outlet pipe 9), the mixed refrigerant flows upstream of the interface region (near the inlet of the refrigerant flowing into the heat exchanger tubes, such as the large-diameter heat exchanger tube assembly 2), while the gaseous refrigerant flows downstream of the interface region (near the outlet of the refrigerant flowing out of the heat exchanger tubes, such as the outlet pipe 9). In heating mode (where the gaseous refrigerant flows in from the outlet pipe 9 and the mixed refrigerant flows out from the large-diameter heat exchanger tube assembly 2), the gaseous refrigerant flows upstream of the interface region (near the inlet of the refrigerant flowing into the heat exchanger tubes, such as the outlet pipe 9), while the mixed refrigerant flows downstream of the interface region (near the outlet of the refrigerant flowing out of the heat exchanger tubes, such as the large-diameter heat exchanger tube assembly 2). That is, in the interface region, the refrigerant exhibits different states in different modes.

[0048] In cooling mode, the mixed refrigerant first flows through the large-diameter heat exchange tube 21 and then exits the heat exchanger through the small-diameter heat exchange tube 31. At this point, the temperature of the mixed refrigerant is low, and the proportion of liquid refrigerant in the first few flows is greater than in the later flows. Therefore, when the mixed refrigerant enters the heat exchanger, specifically the large-diameter heat exchange tube 21, the overall refrigerant flow rate is low due to the higher proportion of liquid refrigerant. However, since the large-diameter heat exchange tube 21 is an internally threaded copper tube, the multiple threads on the inner wall increase the disturbance of the heat exchange boundary layer, thereby improving the heat exchange efficiency of the mixed refrigerant and preventing a decrease in heat exchange efficiency caused by the low refrigerant flow rate. Furthermore, the threads increase the contact area between the liquid refrigerant and the large-diameter heat exchange tube (compared to a plain tube of the same diameter).

[0049] Before the boundary region, the liquid refrigerant in the mixed refrigerant gradually vaporizes into a gaseous state, thus gradually converting the mixed refrigerant into a gaseous refrigeration system. In particular, after passing through the aforementioned boundary region, the mixed refrigerant has already transformed into a gaseous refrigerant. At this point, because the heat exchange due to the refrigerant phase change is significantly reduced, and the flow rate of the gaseous refrigerant is significantly greater than that of the mixed refrigerant, the contribution of phase change heat transfer to heat exchange efficiency is no longer significant. Therefore, in the process after the boundary region, it is necessary to increase the heat exchange efficiency of the gaseous refrigerant. Here, instead of phase change or increased flow rate, expanding the heat exchange area becomes a more effective means.

[0050] Therefore, the process downstream of the interface area requires a larger heat exchange area to enhance heat transfer, without the need for additional internal thread disturbance. Thus, small-diameter heat exchange tubes 31 are used in the process downstream of the interface area. These are smooth tubes with an inner diameter smaller than that of the large-diameter heat exchange tubes 21, and their number is increased to twice the number of large-diameter heat exchange tubes 21. Overall, taking D1 = 9.52 mm and D2 = 7 mm as an example, the heat exchange area per unit length of small-diameter heat exchange tubes (smooth tubes, number 2N) is approximately (7*2) / 9.52 ≈ 1.47 times that of large-diameter heat exchange tubes per unit length (assuming smooth tubes, number N). It is evident that using an increased number of small-diameter heat exchange tubes 31 in the process downstream of the interface area increases the heat exchange area and improves the heat transfer efficiency of the gaseous refrigerant.

[0051] In heating mode, the heat exchanger functions as a condenser, operating on the opposite principle. Gaseous refrigerant flowing into the small-diameter heat exchange tubes undergoes heat exchange, passes through the interface region, and becomes a mixed-phase refrigerant in the subsequent flow. As mentioned earlier, in the first few flows before the interface region (i.e., within the small-diameter heat exchange tubes), the gaseous refrigerant constitutes a large proportion. At this point, the flow velocity within the small-diameter heat exchange tubes is high, eliminating the need for internal thread disturbance. Utilizing a relatively large number of smooth tubes to increase the heat exchange area is the optimal solution for improving the heat exchange efficiency of the gaseous refrigerant. In the flow after the interface region (i.e., within the large-diameter heat exchange tubes), the proportion of gaseous refrigerant decreases, while the proportion of liquid refrigerant becomes relatively large. The flow velocity slows down, and the resistance decreases. Therefore, the internal threads of the large-diameter heat exchange tubes are needed to increase disturbance, thereby improving heat exchange efficiency and reducing resistance. Simultaneously, due to the large tube diameter, even with a slow flow velocity and internal threads, the overall resistance is not significant, thus maintaining the required flow velocity for heat exchange.

[0052] In summary, the variable-diameter high-efficiency finned heat exchanger provided in this embodiment of the invention increases heat exchange efficiency while reducing resistance (meaning more refrigerant flows through the heat exchanger per unit time). Through enthalpy difference chamber experiments, a dual-tube finned heat exchanger of the same external dimensions showed a 5% increase in cooling capacity when used as an evaporator and a 6% increase in heating capacity when used as a condenser.

[0053] Furthermore, the variable-diameter high-efficiency finned heat exchanger provided in this embodiment of the invention employs variable-diameter heat exchange tubes and distinguishes between smooth tubes and internally threaded tubes. This allows for increased turbulence in the mixed refrigerant flow path and increased flow velocity using larger tube diameters, regardless of whether it's cooling or heating mode. In the gaseous refrigerant flow path, smooth tubes reduce resistance, while an increased number of smaller diameter tubes increases the heat exchange area. This improves the overall heat exchange efficiency and heat transfer capacity of the heat exchanger, ensuring high heat exchange efficiency and heat transfer for both the mixed and gaseous refrigerants on both sides of the interface. Therefore, it avoids the problem in conventional heat exchangers where a single heat exchange tube only provides high heat exchange efficiency and heat transfer for one type of refrigerant (mixed or gaseous), resulting in less than ideal heat exchange efficiency and heat transfer on one side of the interface.

[0054] Second Embodiment

[0055] In the first embodiment, the large-diameter heat exchange tube and the small-diameter heat exchange tube are made of the same material, except that the large-diameter heat exchange tube is a smooth tube with a smooth inner wall, while the small-diameter heat exchange tube is an internally threaded tube with internal threads on its inner wall.

[0056] Unlike the first embodiment, in this embodiment, the large-diameter heat exchanger tube and the small-diameter heat exchanger tube are made of different metallic materials. Furthermore, the thermal conductivity of the material of the large-diameter heat exchanger tube is lower than that of the material of the small-diameter heat exchanger tube.

[0057] As a better option, the small-diameter heat exchange tube is a smooth tube, the small-diameter heat exchange tube is an internally threaded tube, and the two are made of different materials, so that the thermal conductivity of the material of the large-diameter heat exchange tube is lower than that of the material of the small-diameter heat exchange tube.

[0058] The above provides a detailed description of the variable-diameter high-efficiency finned heat exchanger provided by this invention. Any obvious modifications made by those skilled in the art without departing from the essence of this invention will constitute an infringement of the patent rights of this invention and will incur corresponding legal liability.

Claims

1. A variable diameter high-efficiency finned heat exchanger, characterized in that... It includes a large-diameter heat exchanger tube and a small-diameter heat exchanger tube connected in sequence; wherein, in the process where the mixed refrigerant is located, the large-diameter heat exchanger tube is used; and in the process where the gaseous refrigerant is located, the small-diameter heat exchanger tube is used. The diameter of the large-diameter heat exchanger tube is larger than that of the small-diameter heat exchanger tube. In the interface area between the mixed refrigerant and the gaseous refrigerant, the large-diameter heat exchanger tube and the small-diameter heat exchanger tube are connected. The small-diameter heat exchange tubes are connected to the large-diameter heat exchange tubes via connecting pipes. One end of the connecting pipe is a large-diameter heat exchange tube, and the other end is two small-diameter heat exchange tubes. The number of small-diameter heat exchange tubes is twice that of the large-diameter heat exchange tubes, which greatly increases the heat exchange area.

2. The variable diameter high-efficiency finned heat exchanger as described in claim 1, characterized in that: The large-diameter heat exchange tube is an internally threaded tube; the small-diameter heat exchange tube is a smooth tube.

3. The variable diameter high-efficiency finned heat exchanger as described in any one of claims 1 to 2, characterized in that: The large-diameter heat exchange tube and the small-diameter heat exchange tube are made of different metal materials; the thermal conductivity of the material of the large-diameter heat exchange tube is lower than that of the material of the small-diameter heat exchange tube.

4. The variable-diameter high-efficiency finned heat exchanger as described in any one of claims 1 to 2, characterized in that: Based on the air intake conditions, air volume, refrigerant parameters, and heat exchange tube structure, the boundary region between the mixed refrigerant and the gaseous refrigerant is determined using simulated heat exchange results.

5. The variable-diameter high-efficiency finned heat exchanger as described in any one of claims 1 to 2, characterized in that: The heat exchanger further includes a shell, a large-diameter heat exchange tube group, a small-diameter heat exchange tube group, and a connecting pipe. The side wall of the shell has large-diameter and small-diameter tube holes. The large-diameter and small-diameter heat exchange tube groups are located inside the shell. The large-diameter heat exchange tube group includes multiple rows of large-diameter heat exchange tubes, and the small-diameter heat exchange tube group includes multiple rows of small-diameter heat exchange tubes. The two ends of the large-diameter and small-diameter heat exchange tubes pass through the shell through the large-diameter and small-diameter tube holes, respectively. One end of the connecting pipe is connected to the large-diameter heat exchange tube, and the other end is connected to the small-diameter heat exchange tube.

6. The variable diameter high-efficiency finned heat exchanger as described in claim 5, characterized in that: The heat exchanger also includes a large-diameter U-shaped tube and a small-diameter U-shaped tube. The large-diameter U-shaped tube is connected between the open ends on the same side of two adjacent large-diameter heat exchange tubes; the small-diameter U-shaped tube is connected between the open ends on the same side of two adjacent small-diameter heat exchange tubes.

7. The variable-diameter high-efficiency finned heat exchanger as described in any one of claims 1 to 2, characterized in that: In cooling mode, the flow path of the mixed refrigerant is located upstream of the boundary region, and the flow path of the gaseous refrigerant is located downstream of the boundary region; in heating mode, the flow path of the gaseous refrigerant is located upstream of the boundary region, and the flow path of the mixed refrigerant is located downstream of the boundary region.

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