Air conditioning exhaust pipe structure with variable bending radius and design method thereof

Abstract

The present invention relates to an air-conditioning exhaust pipe structure with a variable bending radius and a design method thereof, which solves the defect that the air-conditioning exhaust pipe structure with a fixed bending radius cannot meet the actual use needs compared with the prior art. The present invention includes an air-conditioning exhaust pipe, the A end of the air-conditioning exhaust pipe is connected to the exhaust port of the compressor, the B end of the air-conditioning exhaust pipe is connected to the four-way valve S pipe, the air-conditioning exhaust pipe is a regular U-shape, the B end of the air-conditioning exhaust pipe faces upward, and the A end of the air-conditioning exhaust pipe faces downward after being bent in an inverted U shape. The present invention minimizes vibration according to the operation and structural characteristics of components such as compressors; the air-conditioning exhaust pipe is bent with two or more bending radii to meet the complex requirements of different pipe sections for pipeline stress and pipeline spacing; at the same time, on the premise of meeting the reliable performance of the pipeline, the raw materials are minimized to meet the bending rate.

Description

Technical Field

[0001] The invention relates to the technical field of air conditioners, in particular to an air conditioner exhaust pipe structure with a variable bending radius and a design method thereof. Background Art

[0002] When designing the piping of the air conditioner, it is necessary to consider that the piping does not collide, resonate, and prevent stress concentration. The spacing of the piping (anti-collision) requires that the spacing between the piping and its accessories and the operating parts should be greater than 13mm, and the spacing between the piping and the stationary parts should be greater than 10mm. The bending of the piping (anti-stress concentration, reduce vibration) requires that the bending of the piping should be as gentle as possible in the parts with greater stress, and it should be designed as a U or S-shaped structure as much as possible.

[0003] Based on the above requirements, the bending radius of the pipeline should be as large as possible within the range allowed by space, which is beneficial to reducing stress, vibration and the use of raw materials. However, the larger the bending radius, the smaller the distance between the piping bend and the surrounding pipelines, and the anti-collision spacing requirements may not be met.

[0004] However, the traditional production method can only use a fixed bending radius for a pipe, which cannot take into account the different space sizes and vibration requirements of different parts, and cannot achieve the optimal design. The pipe with a fixed bending radius has the following problems:

[0005] 1. Designed to meet the optimal state of stress and vibration, the bending radius is as large as possible, and the space interval of some pipe sections does not meet the optimal requirements;

[0006] 2. In order to meet the optimal design of space interval, the bending radius is as small as possible, and the stress and vibration size do not meet the optimal requirements;

[0007] 3. The process requires that the bending rate of the pipe fitting at the bending cross section is e = long diameter / short diameter ≤ 1.15. At the same bending angle, the larger the bending radius, the smaller the bending rate, and the smaller the bending radius, the larger the bending rate. At the same bending radius, the larger the bending angle, the smaller the bending rate, and the smaller the bending angle, the larger the bending rate. If the bending radius is fixed, the bending rate of parts with different bending angles cannot reach the optimal level, and the bending rate is easy to exceed the standard during processing.

[0008] In practical work, the choice of bending radius is particularly important, especially in the design and processing of air conditioning exhaust pipes. The exhaust pipe is the pipe connecting the compressor exhaust port and the four-way valve S pipe. According to the working principle of air conditioning, the compressor exhaust outlet is a high-temperature and high-pressure gas refrigerant. Therefore, the exhaust pipe is the pipe with the highest pressure and amplitude in the air conditioning system. The design of the exhaust pipe is mainly to reduce stress.

[0009] Then, how to invent an air-conditioning exhaust pipe (road) structure with a variable bending radius, so that different sections of the same pipe can adopt different bending radii according to vibration conditions, stress conditions, and space size, so as to meet the design and processing requirements of the pipeline under complex conditions, has become a technical problem that needs to be solved urgently. Summary of the invention

[0010] The purpose of the present invention is to solve the defect that the air-conditioning exhaust pipe structure with a fixed bending radius in the prior art cannot meet the actual use needs, and to provide an air-conditioning exhaust pipe structure with a variable bending radius and a design method thereof to solve the above problem.

[0011] In order to achieve the above object, the technical solution of the present invention is as follows:

[0012] An air conditioning exhaust pipe structure with a variable bending radius comprises an air conditioning exhaust pipe, wherein the A end of the air conditioning exhaust pipe is connected to the compressor exhaust port, and the B end of the air conditioning exhaust pipe is connected to the four-way valve S pipe.

[0013] The air conditioning exhaust pipe is in a regular U shape, with the B end of the air conditioning exhaust pipe facing upward, and the A end of the air conditioning exhaust pipe facing downward after being bent in an inverted U shape.

[0014] The bending angles of the positive U-shape and the inverted U-shape of the air-conditioning exhaust pipe are 180 degrees; a bending structure A is provided below the B end of the air-conditioning exhaust pipe, and a bending structure B is provided at the connecting section from the inverted U-shape to the positive U-shape of the air-conditioning exhaust pipe.

[0015] The air-conditioning exhaust pipe is composed of pipe section A, bend A, pipe section B, bend B, pipe section C, bend C, pipe section D, bend D, pipe section E, bend E, pipe section F, bend F and pipe section G from end A to end B, wherein pipe section A is the A end of the air-conditioning exhaust pipe and pipe section G is the B end of the air-conditioning exhaust pipe.

[0016] A design method for an air conditioning exhaust pipe structure with a variable bending radius comprises the following steps:

[0017] Determine the basic direction of the exhaust pipe: design the middle bend D of the air-conditioning exhaust pipe to be a regular U-shape, the B end of the air-conditioning exhaust pipe faces upward, and the A end of the air-conditioning exhaust pipe faces downward after being bent in an inverted U-shape at the bend A;

[0018] Design of the bending angles of bends A and D: According to the principle of designing the most shock-absorbing direction along the tangent direction of the compressor suction and exhaust, combined with the spatial structure of the whole machine, determine the angle a between the planes where bends A and D are located;

[0019] Bending design of bend E, pipe section F and bend F: After the angle a is determined, since the end B of the air conditioning exhaust pipe is connected to the four-way valve S pipe, bend E, pipe section F and bend F are bent and connected to ensure that the position and direction of the pipe opening remain unchanged;

[0020] Bending design of pipe section B, elbow B, pipe section C, elbow C and pipe section D:

[0021] According to M (torque) = F (force) * L (arm), under the premise of the force exerted by the compressor on the axial direction of the exhaust pipe, the smaller the arm, the smaller the torque. The air conditioning exhaust pipe is arranged at the closest point to the compressor on the premise of ensuring the gap with the compressor; therefore, the angle a of the plane where the bend A and the bend D are located is designed as a 180° bend, and the bending design of pipe section B, bend B, pipe section C, bend C and pipe section D makes the overall pipeline close to the direction of the compressor, while ensuring that the position and direction of the pipe mouth remain unchanged;

[0022] Determine the outer diameter and wall thickness of the pipe:

[0023] Depending on the position of the pipeline on the pressure-enthalpy diagram, the refrigerant pressure drop in the exhaust pipeline will increase the compressor exhaust pressure, increase the compressor specific work, and reduce the system EER;

[0024] By using the system simulation method, without considering the pressure drop caused by the pipe elbows and the stop valve components on the connecting pipes, the influence of the change of pipe pressure drop on the system performance when using exhaust pipes of different pipe diameters is qualitatively analyzed;

[0025] Since the pipe length is determined by the structural installation, the simulation only focuses on the changes in system performance when the connecting pipe diameter is changed, and the conclusions are used to guide the selection of the exhaust pipe diameter.

[0026] In the step of determining the outer diameter and wall thickness of the pipeline, the processing performance is taken into consideration, and the process requires that the bending flattening ratio be controlled to be ≤1.15, where the bending flattening ratio is the major diameter / minor diameter of the cross section at the bend. For each pipe diameter, 40 groups are processed with different bending radii for data statistics;

[0027] Taking the φ12X0.8 pipeline as an example, within the selected bending radius R≥20, considering the universality of the mold, n fixed values ​​are selected as the standard. Considering the compact design of the pipe diameter, the radius is not the larger the better, so two standard values ​​of R21 and R26 are selected.

[0028] Beneficial Effects

[0029] Compared with the prior art, the air-conditioning exhaust pipe structure with a variable bending radius of the present invention minimizes vibration according to the operation and structural characteristics of components such as compressors; the air-conditioning exhaust pipe is bent with two or more bending radii to meet the complex requirements of different pipe sections for pipeline stress and pipeline spacing; at the same time, on the premise of meeting the reliable performance of the pipeline, the raw materials are minimized to meet the bending flatness rate.

[0030] The design method of the present invention can realize different bending radii for different sections of the same pipe according to vibration conditions, stress conditions, and space size, thereby meeting the design and processing requirements of pipelines under complex conditions. At the same time, the processing method changes the bending radius according to different bending angles, which is conducive to reducing the bending rate and improving product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a structural diagram of a first embodiment of the present invention;

[0032] Figure 2 It is a compressor simulation design diagram in the prior art;

[0033] Figure 3 This is a structural diagram of a second embodiment of the present invention;

[0034] Figure 4 This is a structural diagram of a third embodiment of the present invention;

[0035] Figure 5 A position curve diagram of the pipeline involved in the present invention on the pressure-enthalpy diagram;

[0036] Figure 6 A diagram showing the change in system performance and exhaust pipe diameter involved in the present invention;

[0037] Among them, 1-pipe segment A, 2-elbow A, 3-pipe segment B, 4-elbow B, 5-pipe segment C, 6-elbow C, 7-pipe segment D, 8-elbow D, 9-pipe segment E, 10-elbow E, 11-pipe segment F, 12-elbow F, 13-pipe segment G. DETAILED DESCRIPTION

[0038] In order to have a further understanding and recognition of the structural features and the effects achieved by the present invention, a preferred embodiment and accompanying drawings are used for detailed description as follows:

[0039] A design method for an air conditioning exhaust pipe structure with a variable bending radius comprises the following steps:

[0040] The first step is to determine the basic direction of the exhaust pipe.

[0041] The exhaust pipe is the pipe connecting the compressor exhaust port and the four-way valve S pipe. According to the working principle of air conditioning, the exhaust outlet of the compressor is a high-temperature and high-pressure gas refrigerant. Therefore, the exhaust pipe is the pipe with the largest pressure and amplitude in the air conditioning system. The design of the exhaust pipe is mainly to reduce stress. First of all, in order to reduce the vibration of the pipeline, it needs to be designed into a U shape to make the pipeline flexible. In addition, the compressor exhaust port and the four-way valve S pipe are fixed. According to relevant design requirements, the compressor exhaust port has a straight pipe with a length greater than or equal to 200mm, the pipe mouth is upward, and the four-way valve S pipe is downward. The exhaust pipe connects the two, the pipe mouth position is fixed, and the direction is designed as 2 U-shaped bends, that is, an S-shaped structure.

[0042] The middle bend D8 of the air-conditioning exhaust pipe is designed to be a regular U-shape, the B end of the air-conditioning exhaust pipe faces upward, and the A end of the air-conditioning exhaust pipe faces downward after being bent in an inverted U-shape at the bend A2.

[0043] like Figure 1 As shown, as the first embodiment of the present invention, an air-conditioning exhaust pipe structure with a variable bending radius includes an air-conditioning exhaust pipe, wherein the A end of the air-conditioning exhaust pipe is connected to the compressor exhaust port, the B end of the air-conditioning exhaust pipe is connected to the four-way valve S pipe, and the air-conditioning exhaust pipe is a regular U-shape, the B end of the air-conditioning exhaust pipe faces upward, and the A end of the air-conditioning exhaust pipe faces downward after being bent in an inverted U shape.

[0044] The second step is to design the bending angles of bends A2 and D8: According to the principle that the design along the tangent direction of the compressor suction and exhaust is the most shock-absorbing, combined with the spatial structure of the whole machine, determine the angle a between the planes where bends A2 and D8 are located. According to the experience of piping system design, such as Figure 2 As shown in the figure, the design along the tangent direction of the compressor suction and exhaust is the most shock-absorbing. Combined with the spatial structure of the whole machine, the angle a between the planes where the two U-shaped bends are located is determined.

[0045] The third smallest is the bending design of corner E10, pipe section F11 and corner F12.

[0046] After the angle a is determined, since the other end of the exhaust pipe needs to be connected to the four-way valve S pipe, the bend E10, the pipe section F11 and the bend F12 are bent and connected to ensure that the position and direction of the pipe mouth remain unchanged.

[0047] The fourth step is the bending design of pipe section B3, bend B4, pipe section C5, bend C6 and pipe section D7.

[0048] According to M (torque) = F (force) * L (lever arm), under the premise that the axial force exerted by the compressor on the exhaust pipe is constant, the smaller the lever arm, the smaller the torque. The pipeline is arranged at the closest point to the compressor while ensuring the gap with the compressor; therefore, the angle a of the plane where the bend A2 and the bend D8 are located are each designed as a 180° bend.

[0049] like Figure 3 As shown, as the second embodiment of the present invention, the bending angles of the positive U-shape and the inverted U-shape of the air-conditioning exhaust pipe are 180 degrees; a bending structure A is provided below the B end of the air-conditioning exhaust pipe, and a bending structure B is provided from the inverted U-shape to the positive U-shape connecting section of the air-conditioning exhaust pipe.

[0050] The bending design of pipe section B3, bend B4, pipe section C5, bend C6 and pipe section D7 makes the entire pipeline closer to the direction of the compressor while ensuring that the position and direction of the pipe opening remain unchanged.

[0051] like Figure 4 As shown, as the third embodiment of the present invention, the air-conditioning exhaust pipe is composed of a pipe segment A1, an angle A2, a pipe segment B3, an angle B4, a pipe segment C5, an angle C6, a pipe segment D7, an angle D8, a pipe segment E9, an angle E10, a pipe segment F11, an angle F12 and a pipe segment G13 from end A to end B, wherein pipe segment A1 is the A end of the air-conditioning exhaust pipe, and pipe segment G13 is the B end of the air-conditioning exhaust pipe.

[0052] Step 5: Determine the outer diameter and wall thickness of the pipeline:

[0053] Depending on the position of the pipeline on the pressure-enthalpy diagram, the refrigerant pressure drop in the exhaust pipeline will increase the compressor exhaust pressure, increase the compressor specific work, and reduce the system EER;

[0054] By using the system simulation method, without considering the pressure drop caused by pipe elbows, stop valves on connecting pipes and other components, the influence of the change of pipe pressure drop on the system performance when using exhaust pipes of different diameters is qualitatively analyzed;

[0055] Since the pipe length is determined by the structural installation, the simulation only focuses on the changes in system performance when the connecting pipe diameter is changed, and the conclusions are used to guide the selection of the exhaust pipe diameter.

[0056] Considering the processing performance, the process requires that the bending flattening rate be controlled to meet ≤1.15, and the bending flattening rate is the major diameter / minor diameter of the cross-section at the bending point. For each pipe diameter, 40 groups are processed with different bending radii for data statistics; taking the φ12X0.8 pipe as an example, within the selectable bending radius R≥20, considering the universality of the mold, a small number of fixed values ​​are selected as the standard, and considering the compact design of the pipe diameter, the radius is not the larger the better, so the two standard values ​​of R21 and R26 are selected.

[0057] like Figure 5As shown in the figure, the system simulation method is used to qualitatively analyze the influence of the change of pipeline pressure drop on system performance when using exhaust pipes of different diameters without considering the pressure drop caused by components such as pipeline elbows and stop valves on the connecting pipelines. Since the pipe length is mainly determined by the structural installation, the simulation is only for the change of system performance when the connecting pipe diameter is changed, and the conclusions are used to guide the selection of the exhaust pipe diameter.

[0058] The simulation object and simulation conditions take a 3500W refrigeration capacity R410A household heat pump variable frequency air conditioning system as the research object, in which the compressor, condenser, evaporator, electronic expansion valve, liquid pipe and two-phase liquid pipe and other components remain unchanged, the length of the suction and exhaust pipes remains unchanged, only the diameter of the exhaust pipe is changed, and both are well insulated. The calculation condition is set as the rated refrigeration condition, and the system operating parameters are given in Table 1.

[0059] Table 1

[0060]

[0061] The exhaust pipes are made of ∮12×0.8mm, ∮9.52×0.71mm,

[0062] The systems of ∮8×0.65mm, ∮7×0.6mm, ∮×0.5mm, ∮5×0.5mm, ∮5×0.75mm and ∮4×0.5mm were simulated and calculated, among which the intake pipe adopted the unchanged specification of ∮9.52mm×0.71mm.

[0063] Through the system simulation method, the rated refrigeration performance of the air-conditioning system with a refrigeration capacity of 3500W is analyzed under certain conditions of condenser outlet subcooling when only the exhaust pipe diameter is changed. The main conclusions are as follows:

[0064] 1) The change of the exhaust pipe diameter mainly affects the thermal parameters, system power consumption and EER of the high-pressure side, and has little effect on the cooling capacity of the system.

[0065] 2) When the exhaust pipe diameter is reduced from ∮12mm to ∮6mm, the system performance changes very little and can basically be considered unchanged.

[0066] 3) Taking the system performance with zero refrigerant pressure drop in the exhaust pipe as the benchmark, the system cooling capacity and EER or system power consumption and EER will decrease by about 2% for every 1K increase in the saturated temperature drop of the refrigerant in the exhaust pipe. Therefore, the exhaust pipe can be directly selected within the conventional pipe diameter range. For large cooling capacity models, the saturated temperature drop can be controlled within 1K as the design and selection basis of the exhaust pipe. Figure 6 shown.

[0067] It can be concluded that the exhaust pipe diameter of household air conditioners 3P and below can be selected within the specifications in the following table, as shown in Table 2:

[0068] Table 2

[0069] Copper tube specifications (tube diameter x wall thickness) (mm) φ6X0.5 φ7X0.6 φ8X0.75 φ9X0.65 φ9.52X0.71 φ12X0.8

[0070] 3. Determine the bending radius of each section of the pipeline

[0071] First, the processing performance is considered. The process requires that the bending flattening ratio (long diameter / short diameter of the cross section at the bend) be controlled to meet ≤1.15. For each pipe diameter, 40 groups of different bending radii are processed and data statistics are performed. The results are shown in Table 3:

[0072] Table 3

[0073]

[0074] The above data are integrated and analyzed to show that the smaller the bending radius of the same specification pipeline, the greater the bending flattening rate. The range of bending radius that can be selected for pipeline fittings of various specifications that meet the bending flattening rate is shown in Table 4:

[0075] Table 4

[0076]

[0077]

[0078] Taking the φ12X0.8 pipeline as an example, within the range of the selectable bending radius R≥20, considering the universality of the mold, a few fixed values ​​are generally selected as the standard, and considering the compact design of the pipe diameter, the radius selection is not the larger the better, so two standard values ​​of R21 and R26 are selected. Combined with the basic bending characteristics of the determined pipeline structure, three structural pipelines are designed with different bending radii, and stress experiments are compared under the same working conditions. The maximum stress values ​​at each measuring point are shown in Table 5:

[0079] Table 5

[0080]

[0081] From the experimental data, it can be concluded that when the bending radius increases at corners 1 and 4, the stress value decreases, while when the bending radius increases at corners 2, 3, 5, and 6, the stress value does not change significantly. Therefore, a larger bending radius is used at corners 1 and 4, which not only reduces stress but also reduces the change in wall thickness, saving the use of copper tube materials. A smaller bending radius is used at corners 1, 3, 5, and 6 to increase the spacing from surrounding pipes and parts.

[0082] In the actual design process, the direction, specifications, bending radius, space and plane angle of the pipeline are first determined, and then combined with experimental data, the structure is fine-tuned to avoid the resonance frequency point of the compressor, and finally the pipeline structure is determined.

[0083] When designing piping for air conditioners, consideration should be given to preventing the piping from colliding, resonating, and stress concentration. The spacing of piping (to prevent collision) requires that its bending radius be as small as possible. The bending of piping (to prevent stress concentration) requires that the curvature of the piping should be as gentle as possible and the bending radius should be as large as possible in the parts that bear greater stress. Therefore, a pipeline structure and processing method with a variable bending radius are invented to achieve different bending radii for different sections of the same pipe according to vibration conditions, stress conditions, and space size, thereby meeting the design and processing requirements of pipelines under complex conditions.

[0084] Combined with the design space of the air-conditioning pipeline, the bending rate data of the processing process, and the pipeline operation stress experimental test data, the bending radius at different positions, different bending angles, different pipe diameters, and different wall thicknesses is determined.

[0085] First of all, since the smaller the bending radius, the greater the flattening rate, in order to meet the processing quality requirements, according to our company's copper tube raw material specification standards, while meeting the flattening rate, the bending radius range values ​​of copper tubes with different diameters and wall thicknesses are determined, as shown in Table 6.

[0086] Table 6

[0087]

[0088] Secondly, within the bending radius range that meets the requirements of production and processing, in accordance with the principles of standardization and generalization, two different fixed bending radius values ​​are selected for each specification of copper tube as standard values ​​for production and processing, as shown in Table 7.

[0089] Table 7

[0090]

[0091] Then, according to the pipeline design space and seismic requirements, confirm the approximate direction of the pipeline fittings, determine the bending angle of each bend in the pipeline, and select the standard bending radius according to the bending angle and structural design requirements, as shown in Table 8.

[0092] Table 8

[0093]

[0094] Finally, the bending radius is modified and optimized according to the stress and vibration test data during pipeline operation. At the same time, the processing efficiency and material consumption are taken into consideration to obtain the final design scheme of the variable bending radius pipeline.

[0095] In terms of production and processing, based on universal requirements, since two fixed bending radius values ​​are selected for each specification of copper tube, compound circular molds and clamping molds are designed according to these two bending radii to achieve variable curvature processing.

[0096] Of course, the executable implementation method is not limited to the standard values ​​selected above. Within the range that satisfies the processing, 2 or more bending radii can be arbitrarily selected for each copper tube specification for composite processing.

[0097] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for designing an air conditioning exhaust pipe structure with a variable bending radius, the air conditioning exhaust pipe structure with a variable bending radius comprising an air conditioning exhaust pipe, wherein end A of the air conditioning exhaust pipe is connected to an exhaust port of a compressor, and end B of the air conditioning exhaust pipe is connected to a four-way valve S pipe, the air conditioning exhaust pipe is a regular U-shape, end B of the air conditioning exhaust pipe faces upward, and end A of the air conditioning exhaust pipe faces downward after being bent in an inverted U-shape; the air conditioning exhaust pipe comprises, from end A to end B, a pipe section A (1), an angle A (2), a pipe section B (3), an angle B (4), a pipe section C (5), an angle C (6), a pipe section D (7), an angle D (8), a pipe section E (9), an angle E (10), a pipe section F (11), an angle F (12), and a pipe section G (13), wherein: Pipe section A (1) is end A of the air conditioning exhaust pipe, and pipe section G (13) is end B of the air conditioning exhaust pipe; The design method comprises the following steps: 11) Determine the basic direction of the exhaust pipe: Design the middle bend D (8) of the air-conditioning exhaust pipe to be a regular U-shape, with the B end of the air-conditioning exhaust pipe facing upward, and the A end of the air-conditioning exhaust pipe facing downward after being bent in an inverted U-shape at the bend A (2); 12) Design of the bending angles of corners A (2) and D (8): Based on the principle of designing along the tangent direction of the compressor suction and exhaust for best vibration reduction, and in combination with the spatial structure of the entire machine, determine the angle a between the planes where corners A (2) and D (8) are located; 13) Bending design of bend E (10), pipe section F (11) and bend F (12): After the angle a is determined, since the end B of the air conditioning exhaust pipe is connected to the four-way valve S pipe, bend E (10), pipe section F (11) and bend F (12) are bent and connected to ensure that the position and direction of the pipe opening remain unchanged; 14) Bending design of pipe section B (3), elbow B (4), pipe section C (5), elbow C (6) and pipe section D (7): According to M=F*L, M is the moment, F is the force, and L is the lever arm. Under the premise that the compressor acts on the exhaust pipe in the axial direction, the smaller the lever arm, the smaller the torque. The air conditioning exhaust pipe is arranged at the closest point to the compressor while ensuring the clearance with the compressor. Therefore, the angle a of the plane where the bend A (2) and the bend D (8) are located is designed as a 180° bend. The bend design of pipe section B (3), bend B (4), pipe section C (5), bend C (6) and pipe section D (7) makes the whole pipe close to the compressor while ensuring that the position and direction of the pipe opening remain unchanged. 15) Determine the outer diameter and wall thickness of the pipeline: Depending on the position of the pipeline on the pressure-enthalpy diagram, the refrigerant pressure drop in the exhaust pipeline will increase the compressor exhaust pressure, increase the compressor specific work, and reduce the system EER; By using the system simulation method, without considering the pressure drop caused by the pipe elbows and the stop valve components on the connecting pipes, the influence of the change of pipe pressure drop on the system performance when using exhaust pipes of different pipe diameters is qualitatively analyzed; Since the pipe length is determined by the structural installation, the simulation only focuses on the changes in system performance when the connecting pipe diameter is changed, and the conclusions are used to guide the selection of the exhaust pipe diameter.

2. The design method of an air conditioning exhaust pipe structure with a variable bending radius according to claim 1 is characterized in that: In the step of determining the outer diameter and wall thickness of the pipeline, the processing performance is taken into consideration and the process requires that the bending flattening ratio be controlled to be ≤1.

15. The bending flattening ratio is the major diameter / minor diameter of the cross section at the bend. For each pipe diameter, 40 groups are processed with different bending radii for data statistics.

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