Micro-channel heat exchanger

Abstract

The application discloses a micro-channel heat exchanger, which comprises a plurality of parallel inner refrigerant pipes, and spiral fins are arranged between the pipes, and the two ends of the spiral fins are fixed with the adjacent pipes respectively. In the application, the fins adopt the spiral structure, the drainage efficiency is high, and the fins are not easy to accumulate dust, so that the heat dissipation efficiency is high. The spiral fin in the application has higher structural strength compared with the conventional structures such as flat fins, column ribs and needle ribs, is stable during manufacturing, transportation and installation, is easy to process, and is beneficial to improving the manufacturing and installation efficiency and reducing the cost.

Description

Technical Field

[0001] The present invention relates to a heat exchange device, and more specifically, to a microchannel heat exchanger. Background Technology

[0002] Currently, the heat exchangers used in refrigeration and air conditioning mainly consist of copper tubes combined with aluminum fins. With the continuous increase in copper prices, the cost of heat exchangers is also rising, hindering product adoption and energy efficiency improvements. While microchannel heat exchangers have made significant progress in replacing copper tube and aluminum fin heat exchangers, particularly in condenser replacement in single-cooling products, their application in heat pump air conditioners is still limited and remains in the research stage. The main reason is the lack of breakthrough in addressing the condensate drainage problem of microchannel heat exchangers, leading to frequent frosting and defrosting of the outdoor heat exchanger during winter heating, severely impacting the air conditioner's heating performance. The main reason for this is that the fins of the microchannel heat exchanger are arranged perpendicularly to the pipes, which are mostly flat tubes. When the wider side of the flat tube is placed horizontally, the condensate on the flat tube does not easily collect and flow down. When the wider side of the flat tube is placed vertically, the fins are placed horizontally, and the tension between the fins and the condensate is small, so the condensate does not easily collect. In addition, microchannel heat exchangers need to be welded during the manufacturing process, resulting in a large surface roughness and a large contact angle with the condensate, making drainage very difficult. In existing technologies, fins mainly include flat fin structures, column fin structures, and pin fin structures. Flat fin structures have a large contact angle with condensate, and due to capillary effects, condensate has difficulty flowing on the fins, resulting in drainage difficulties. Furthermore, the thinness of flat fin structures leads to a thick laminar boundary layer when airflow passes over the fin surface, resulting in high thermal resistance. Consequently, the heat transfer coefficient of fins with fins is relatively low. While column fin structures can reduce the contact angle between condensate and fins, eliminate capillary effects, facilitate condensate drainage, greatly improve drainage efficiency, extend defrosting time, and reduce frequent frosting and defrosting, thus improving the heating performance of air conditioners, column fin structures are difficult to process, have complex processes, and high production costs. Pin fin structures have an even higher distribution density than column fin structures, are more difficult to process, and have lower strength, making them more prone to damage. Summary of the Invention

[0003] Existing microchannel heat exchangers suffer from limitations in fin structure and pipe-fin fit, making condensate drainage difficult. This leads to frequent frost formation and defrosting during heating, severely impacting heat exchange efficiency. To overcome this deficiency, this invention provides a microchannel heat exchanger that improves fin structure and pipe-fin fit, facilitating condensate drainage and enhancing heat exchange efficiency.

[0004] The technical solution of this invention is: a microchannel heat exchanger, comprising multiple parallel pipes internally connected to refrigerant, with spiral ribs between the pipes, and the two ends of the spiral ribs fixed to adjacent pipes respectively. In this invention, the fins are presented in the form of spiral ribs. Because the fins adopt a spiral structure, they have an angle with both the horizontal and vertical directions. Regardless of whether the microchannel heat exchanger is placed horizontally or vertically, the contact angle of condensate droplets on the spiral ribs is small, making them easy to slide off, thus improving drainage efficiency. The spiral structure has a larger spatial gap, making it less prone to dust accumulation. Simultaneously, the spiral structure has lower flow resistance, lower airflow pressure loss, and better heat exchange performance. Fine dust is more easily blown off, further reducing dust accumulation. The spiral ribs, made of twisted metal wire, have superior metal density, yield strength, tensile strength, and wear resistance. Therefore, spiral ribs have higher structural strength than the straight structures of flat fins, column ribs, and needle ribs, exhibiting better stability during manufacturing, transportation, and installation, which is beneficial for improving manufacturing and installation efficiency and reducing costs. Therefore, fins using spiral ribs provide smooth drainage, are less prone to dust accumulation, have high heat dissipation efficiency, high strength, and are easy to process.

[0005] Preferably, there is a pipe gap between adjacent pipes, and multiple spiral rib assemblies are provided within the same pipe gap. The spiral rib assembly is integrally formed from multiple spiral ribs. Integrating multiple spiral ribs onto the same spiral rib assembly can reduce the amount of installation work for the spiral ribs and improve the production efficiency of the microchannel heat exchanger.

[0006] Preferably, the spiral rib assembly is formed by winding a single metal wire into a helical tube and then bending it in a wavy shape. The pitch t of the spiral rib ranges from 0.8D to H*D / d, the lateral spacing A of the spiral rib ranges from 0.5D to D+D*D / d, and the longitudinal spacing B ranges from 0.5D to D+H*D / d. The contact angle β between the metal wire and the pipe at the connection between the spiral rib and the pipe satisfies the relationship β=arctan(D / t*k1), where d is the diameter of the metal wire, D is the spiral diameter of the spiral rib, H is the pipe spacing, and k1 ranges from 0.1 to 2. In the prior art, spiral winding and bending can both be completed using specialized equipment, and the spiral rib assembly can also be processed and manufactured using existing equipment, making the spiral rib easy to realize. The numerical ranges of the spiral rib pitch and distribution spacing are determined based on existing material specifications, taking into account the actual heat exchange effect and processing difficulty.

[0007] Preferably, this microchannel heat exchanger also includes an inlet distribution pipe and an outlet manifold, with both ends of the pipe sealed to the inlet distribution pipe and the outlet manifold, respectively. The connection of the pipe, the inlet distribution pipe, and the outlet manifold forms a stable structure and establishes a pipeline connection.

[0008] Preferably, the pipes are flat, and the planes of the inlet distribution pipe and the outlet manifold form an inclined angle with the wider face of the pipe. In this way, whether the microchannel heat exchanger is placed horizontally or vertically during use, the wider face of the flat pipe can be in an inclined state, which can better facilitate the collection and discharge of condensate on the surface of the pipe.

[0009] Preferably, the spiral ribs are made of the same material as the pipe. The spiral ribs need to be welded to the pipe for fixation; using the same material for both ensures better fusion during welding.

[0010] As a preferred option, the spiral ribs are made of aluminum wire. Aluminum has good thermal conductivity and is relatively inexpensive. Using aluminum wire to make the spiral ribs can ensure the heat exchange effect of the microchannel heat exchanger while controlling production costs.

[0011] Alternatively, the spiral ribs can be made of copper wire. Copper has good thermal conductivity and a long service life, while using aluminum wire to make the spiral ribs can ensure the heat exchange effect of the microchannel heat exchanger and also have a long service life.

[0012] Alternatively, spiral ribs can be made of iron wire. Iron is inexpensive and easy to weld, which can significantly reduce costs.

[0013] The beneficial effects of this invention are:

[0014] High heat dissipation efficiency. The fins in this invention adopt a spiral structure, which has high drainage efficiency and is not prone to dust accumulation, thus exhibiting high heat dissipation efficiency.

[0015] Easy to process and reduces costs. The spiral ribs in this invention have higher structural strength than conventional structures such as flat plates, column ribs, and pin ribs. They are more stable during manufacturing, transportation, and installation, and are easier to process, which helps to improve manufacturing and installation efficiency and reduce costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of one structure of the present invention;

[0017] Figure 2 This is a cross-sectional view of the present invention;

[0018] Figure 3 This is a schematic diagram of the distribution of spiral ribs on the longitudinal section of the present invention;

[0019] Figure 4 This is a partially enlarged view of the present invention;

[0020] Figure 5 This is a schematic diagram of the pipe positioning clamp in this invention;

[0021] Figure 6 This is a schematic diagram showing the usage state of the pipe positioning clamp in this invention;

[0022] Figure 7 This is another structural schematic diagram of the present invention.

[0023] In the diagram, 1-pipe, 2-spiral rib, 3-input distribution pipe, 4-output manifold, 5-pipe positioning fixture, 6-top frame, 7-bottom frame, 8-connecting rod, 9-pipe positioning seat, 10-positioning seat fixing block, 11-positioning seat bracket, 12-ring, 13-support rod, 14-bottom frame slider, 15-adjusting screw. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0025] Example 1:

[0026] like Figures 1 to 6 As shown, a microchannel heat exchanger includes 17 parallel pipes 1 internally circulated with refrigerant, as well as parallel inlet distribution pipes 3 and outlet manifolds 4. The two ends of each pipe 1 are sealed to the inlet distribution pipes 3 and the outlet manifolds 4, respectively. Spiral ribs 2 are provided between the pipes 1, with each end of the spiral rib 2 fixed to an adjacent pipe 1. There is a pipe gap between adjacent pipes 1, and three spiral rib assemblies are provided within the same pipe gap. Each spiral rib assembly is integrally formed from 100 spiral ribs 2. Each spiral rib assembly is formed by winding a single metal wire into a helical tube shape and then bending it in a wavy shape. The pipes 1 are flat tubes, and the plane containing the inlet distribution pipes 3 and the outlet manifolds 4 forms an inclined angle α with the wider surface of the pipe 1. In this embodiment, this angle is 60°. The spiral ribs 2 are made of the same material as the pipes 1; the spiral ribs 2 are made of aluminum wire, and the pipes 1 are aluminum tubes. The spiral rib assembly is formed by winding a single metal wire into a solenoid shape and then bending it in a wavy shape. The diameter d of the metal wire is 0.01-3 mm, the spiral diameter D of the spiral rib 2 is 0.1-5 mm, the pipe spacing H is 5-20 mm, the pitch t of the spiral rib 2 ranges from 0.8D to H*D / d, the lateral spacing A of the spiral rib 2 ranges from 0.5D to D+D*D / d, and the longitudinal spacing B ranges from 0.5D to D+H*D / d. The contact angle β between the metal wire and the pipe 1 at the connection between the spiral rib 2 and the pipe 1 satisfies the relationship β=arctan(D / t*k1), where k1 is a coefficient with a value ranging from 0.1 to 2. In this embodiment, d=0.3 mm, D=0.5 mm, t=1 mm, H=10 mm, k1=0.5, A=0.5 mm, B=0.5 mm, and β=14°.

[0027] The table below shows a comparison of the test results of the heat exchange performance of conventional flat fin structure, needle fin structure, and spiral fin structure in this invention.

[0028]

[0029] Test results show that the spiral rib structure fins used in this invention have higher heat dissipation efficiency than traditional flat fin structure fins, with the former having a heat exchange performance approximately 1.4 times that of the latter.

[0030] The fabrication method of this microchannel heat exchanger includes the following steps:

[0031] Step 1. Fabricate the pipe positioning clamp 5; the pipe positioning clamp 5 includes a top frame 6, a bottom frame 7, and four connecting rods 8. The top frame 6 and the bottom frame 7 are rectangular frames of the same size and are each composed of a front frame, a rear frame, and a pair of side frames connected together. The four connecting rods 8 are of equal length and are respectively hinged at the four corners of the bottom frame 7. The two ends of the rear frame of the top frame 6 are hinged to the two connecting rods 8 on the rear frame of the bottom frame 7. The top ends of the two connecting rods 8 on the front frame of the bottom frame 7 are provided with rings 12 formed by two semi-circular rings hinged together and locked with bolts, which are used to lock or release the two ends of the front frame of the top frame 6; a support rod 13 is provided between the connecting rods 8 on the front frame of the bottom frame 7 and the side frame of the bottom frame 7. The bottom end of the support rod 13 is hinged to a bottom frame slider 14, and the bottom frame slider 14 is slidably connected to the side frame of the bottom frame 7. The bottom frame slider 14 is also threadedly connected to an adjusting screw 15, which has a hexagonal head. The top of the support rod 13 is hinged to the connecting rod 8 on the front frame of the bottom frame 7. The side frames of the top frame 6 and the bottom frame 7 are provided with pipe positioning seats 9. The pipe positioning seats 9 are symmetrically arranged on the side frames of the top frame 6 and the bottom frame 7, and the positions of the pipe positioning seats 9 on the top frame 6 and the pipe positioning seats 9 on the bottom frame 7 correspond one-to-one. The pipe positioning seats 9 have U-shaped bayonet slots that are adapted to the top and bottom of the pipe 1. The side frame is provided with a positioning seat fixing block 10, and a positioning seat bracket 11 is hinged to the positioning seat fixing block 10. The pipe positioning seat 9 on the top frame 6 is provided with a screw rod, which passes through the positioning seat bracket 11 and is fixed with a nut, so that the height of the pipe positioning seat 9 is adjustable.

[0032] Step 2. By rotating the adjusting screw 15, keep the connecting rod 8 perpendicular to the top frame 6 and the bottom frame 7, and position the pipes 1 one by one on the pipe positioning fixture 5. During positioning, the narrower side of the pipe 1 is parallel to the top frame 6 and the bottom frame 7, and the wider side of the pipe 1 is perpendicular to the top frame 6 and the bottom frame 7. The pipe 1 spans the pipe positioning fixture 5, and the bottom of the pipe 1 is stuck on the pipe positioning seats 9 corresponding to the two side frames of the bottom frame 7. The top of the pipe 1 is stuck on the pipe positioning seats 9 corresponding to the two side frames of the top frame 6. During this process, the nuts on the pipe positioning seats 9 of the top frame 6 need to be loosened or tightened appropriately to adjust the height of the pipe positioning seats 9 so that the pipe 1 can smoothly enter the U-shaped bayonet of the pipe positioning seat 9 and be locked to prevent it from falling off.

[0033] Step 3. Insert the spiral rib assembly into the gap of the pipe and braze it one by one to weld the spiral rib assembly onto the pipe 1;

[0034] Step 4. By rotating the adjusting screw 15, the connecting rod 8 is tilted by 60°, the top frame 6 and the bottom frame 7 are misaligned, and the wider side of the pipe 1 forms a 60° angle with both the top frame 6 and the bottom frame 7.

[0035] Step 5. Align and weld the input distribution pipe 3 and the output collector pipe 4 to both ends of pipe 1 respectively;

[0036] Step 6. Adjust the height of the pipe positioning seat 9 on the top frame 6, loosen the bolts on the ring 12, release the two ends of the front frame of the top frame 6, and then flip and lift the top frame 6 around the rear frame of the top frame 6 to remove the welded microchannel heat exchanger from the pipe positioning clamp 5.

[0037] Example 2:

[0038] In this embodiment, d = 0.1 mm, D = 1 mm, t = 3.34 mm, H = 5 mm, k1 = 0.5, A = 11 mm, B = 51 mm, and β = 8.5°. The rest is the same as in Embodiment 1.

[0039] Example 3:

[0040] In this embodiment, d = 3mm, D = 5mm, t = 4mm, H = 20mm, k1 = 0.1, A = 2.5mm, B = 2.5mm, and β = 7.1°. The rest is the same as in Embodiment 1.

[0041] Example 4:

[0042] The plane containing the input distribution pipe 3 and the output collector pipe 4 forms a 45° angle with the wider surface of the pipe 1. In step four, the connecting rod 8 is tilted at 45°, and the wider surface of the pipe 1 forms a 45° angle with both the top frame 6 and the bottom frame 7. The rest is the same as in embodiment 1.

[0043] Example 5:

[0044] Two spiral rib assemblies are provided within the same pipe gap, each spiral rib assembly being integrally formed from 120 spiral ribs 2. The planes containing the input distribution pipe 3 and the output manifold 4 form a right angle with the wider surface of pipe 1. The rest is the same as in Embodiment 1.

[0045] Example 6:

[0046] Spiral rib 2 is made of copper wire. The rest is the same as in Example 1.

[0047] Example 7:

[0048] Spiral rib 2 is made of iron wire. The rest is the same as in Example 1.

[0049] Example 8:

[0050] like Figure 7As shown, the spiral rib 2 is an independent component, without a spiral rib assembly. During the fabrication of the microchannel heat exchanger, the spiral ribs 2 are welded onto the pipe 1 one by one. The rest is the same as in Example 1.

Claims

1. A microchannel heat exchanger comprising a plurality of parallel, internally refrigerant-carrying tubes, characterized in that, The pipes are equipped with helical ribs, with each end of the helical rib fixed to an adjacent pipe. There is a gap between the adjacent pipes. Multiple helical rib assemblies are installed within the same gap. The helical rib assembly is formed by winding a single metal wire into a helical tube and then bending it in a wavy shape. The contact angle β between the metal wire and the pipe at the connection between the helical rib and the pipe satisfies the relationship β=arctan(D / t*k1), where D is the helical diameter of the helical rib, t is the pitch of the helical rib, k1 ranges from 0.1 to 2, the metal wire diameter d is from 0.01 to 3 mm, the helical diameter D of the helical rib is from 0.1 to 5 mm, the pitch t of the helical rib ranges from 0.8D to H*D / d, the lateral spacing A of the helical ribs ranges from 0.5D to D+D*D / d, the longitudinal spacing B ranges from 0.5D to D+H*D / d, and H is the pipe spacing.

2. The microchannel heat exchanger of claim 1, wherein, The spiral rib assembly is formed by integrally molding multiple spiral ribs.

3. The microchannel heat exchanger of claim 1, wherein, It also includes parallel input distribution pipes and output manifolds, with both ends of the pipes sealed to the input distribution pipe and the output manifold, respectively.

4. The microchannel heat exchanger according to claim 1, characterized in that, The pipe is a flat pipe, and the planes where the input distribution pipe and the output manifold are located form an inclined angle with the wider side of the pipe.

5. The microchannel heat exchanger according to any one of claims 1 to 4, characterized in that, The spiral ribs are made of the same material as the pipe.

6. The microchannel heat exchanger according to any one of claims 1 to 4, characterized in that, The spiral ribs are made of aluminum wire.

7. The microchannel heat exchanger according to any one of claims 1 to 4, characterized in that, The spiral ribs are made of copper wire.

8. The microchannel heat exchanger according to any one of claims 1 to 4, characterized in that, The spiral ribs are made of iron wire.

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