A heat exchanger fin defrosting device and defrosting method
By using electromagnetic energy storage to vibrate the fins, the problems of high defrosting energy consumption and easy fin damage in heat exchangers are solved, achieving rapid and effective defrosting while maintaining heat transfer performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING NORMAL UNIVERSITY
- Filing Date
- 2023-11-14
- Publication Date
- 2026-08-04
AI Technical Summary
Existing heat exchanger defrosting methods suffer from high energy consumption, easy damage to fins, or incomplete defrosting. In particular, frost formation on fins at low temperatures severely affects heat transfer performance.
The method of using electromagnets to store energy in the fins involves storing energy in the fins using an electromagnetic field. After the electromagnetic force is removed, the fins vibrate under the action of elastic potential energy, breaking and detaching from the ice layer.
It achieves rapid and effective defrosting, reduces energy consumption, avoids fin damage, and maintains good heat transfer performance.
Smart Images
Figure CN117553498B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of heat exchanger defrosting auxiliary equipment, specifically relating to a heat exchanger fin defrosting device and defrosting method. Background Technology
[0002] When heat needs to be absorbed from the air, a low-temperature cold source needs to be placed in the air, with its temperature much lower than the air temperature. The cold source absorbs heat from the air, causing the air temperature to drop. Examples include air source heat pump heating, cold storage spaces, and maintaining a low temperature in refrigerator or freezer compartments.
[0003] Low-temperature cold sources are typically heat exchangers. The low-temperature medium (refrigerant) flows inside the heat transfer tubes of the heat exchanger. The heat of the air outside the heat transfer tubes is absorbed by the refrigerant through the heat transfer tubes, thereby lowering the air temperature. Because the heat transfer capacity between air and heat transfer tubes is relatively poor, fins must be installed on the surface of the heat transfer tubes to enhance the heat transfer between the air and the heat transfer tubes.
[0004] When heat exchangers, acting as low-temperature cold sources, operate in cold air environments, such as air-source heat pumps providing heating in winter, the fin surface temperature can drop below 0°C. Water vapor in the air easily condenses on the fin surface, and this frost formation continues as the heat exchanger operates. Over time, this results in a thick layer of ice forming on the fin surface. This ice layer not only reduces the heat transfer performance of the heat exchanger but also increases the resistance to airflow, both of which reduce the heat exchanger's energy efficiency. Therefore, the ice layer must be treated to eliminate its harmful effects.
[0005] Existing heat exchanger defrosting methods mainly include the following: 1. Mechanical defrosting: This involves using machinery or tools to act on the ice layer, causing it to detach from the heat exchanger surface. The disadvantage of this method is that, due to the poor rigidity of the heat exchanger fins, defrosting tools can easily deform or damage the fins. Also, if the ice layer is tightly bonded to the heat exchanger surface, this method is difficult to completely remove the ice layer. 2. Thermal defrosting: This involves heating the ice layer to melt it and detach it from the heat exchanger surface. The disadvantage of this method is that it requires a large amount of energy to melt the frost. 3. Ultrasonic defrosting: This method applies ultrasonic excitation, causing the ice layer to vibrate, break up, and detach from the surface, achieving the purpose of defrosting. The disadvantage of this method is that the ultrasonic waves need to act directly on the ice layer to be effective; the intensity of the ultrasonic waves decreases sharply after being blocked. For densely arranged heat transfer tubes and fins in a heat exchanger, the proper arrangement of the ultrasonic source is crucial for effective defrosting; therefore, it is difficult to defrost the ice layer on all heat exchanger surfaces. Summary of the Invention
[0006] To solve the above problems, the present invention provides a defrosting device and method for heat exchanger fins. The device uses an electromagnet to store energy in the form of elastic potential energy in the bent fins. After the electromagnetic force is removed, the bent fins reciprocate under the action of elastic potential energy, thereby achieving the purpose of rapid defrosting of the fins.
[0007] To achieve the above objectives, the technical solution of the present invention is as follows:
[0008] A defrosting device for heat exchanger fins includes a finned heat exchanger with multiple sets of fins. The fins have evenly spaced mounting holes, and heat transfer tubes pass through these holes and are fixedly connected to the multiple sets of fins in a crisscross pattern. Electromagnets are installed at both ends of the finned heat exchanger, located at the left and right ends of the fin assembly. The two sets of electromagnets are powered by a DC power supply with a controller in a power control box. A portion of the fins is made of permanent magnet material. Frost detectors and displacement detectors are installed on the fins. The signals detected by the frost detectors and displacement detectors are sent to the controller in the power control box to control the DC power supply to the two sets of electromagnets.
[0009] In this technical solution, the connection between the fins and the heat transfer tube is a non-magnetic metal part, and the part of the fins away from the heat transfer tube is a permanent magnet material part.
[0010] Furthermore, the permanent magnet material portion includes N poles and S poles. The relative positions of the N poles and S poles of the permanent magnet material portions of the left and right adjacent fins are the same, while the relative positions of the N poles and S poles of the permanent magnet material portions of the upper and lower adjacent fins are opposite.
[0011] Furthermore, the fins are straight fins.
[0012] Furthermore, the fins are curved and wavy fins, with permanent magnet material at the crests and troughs of the fins, and magnetic strips of permanent magnet material are provided thereon. The material connecting the crests and troughs is a non-magnetic metal part.
[0013] Furthermore, the permanent magnet material is one of neodymium iron boron, aluminum nickel cobalt, or ferrite.
[0014] Furthermore, the non-magnetic metal is one of aluminum, aluminum alloys, or copper.
[0015] Furthermore, the defrosting method using the above-mentioned heat exchanger fin defrosting device includes the following steps:
[0016] A. During the operation of the finned heat exchanger, when the frost detector detects ice on the fin surface, the controller in the power control box connects the DC power supply to the circuit of the electromagnet, and the electromagnet generates an electromagnetic field.
[0017] B. An electromagnetic field acts on the permanent magnet material of the fin, forming a bending angle. During this process, the work done by the electromagnetic force on the magnetic strip is stored in the bent fin.
[0018] C. When the displacement detector detects the displacement of the fins, the controller disconnects the DC power supply from the electromagnet, the electromagnetic field of the electromagnet disappears, and the electromagnetic force between the electromagnet and the fins disappears.
[0019] D. Fins not subjected to electromagnetic force vibrate under the action of elastic force, and the vibration will cause the ice layer on the surface of the fins to break and fall off.
[0020] E. After the ice layer falls off, the vibration of the fins gradually stops, and the fins return to their initial state, completing the surface defrosting of the fins;
[0021] F. Frost forms again on the fin surface, and the above AE process restarts, realizing the frost formation and defrosting cycle on the heat exchanger fin surface.
[0022] Furthermore, in step B, the fin is a curved wavy fin. The electromagnetic field acts on the magnetic strips of the permanent magnet material at the crests and troughs of the fin, generating a force opposite to the initial bending direction of the fin, causing the fin to bend in the opposite direction to the initial bending direction. During this process, the work done by the electromagnetic force on the magnetic strips is stored in the fin.
[0023] In this technical solution, the heat exchanger fin defrosting utilizes the principle of fin and ice layer vibration defrosting. Specifically, electromagnetic force is used to store energy in the fins as elastic potential energy. After the electromagnetic force is removed, the fins reciprocate under the action of elastic potential energy. This vibration generates compressive stress within the ice layer attached to the fin surface, causing the ice layer to break. The vibration also generates shear stress between the fin and the ice layer interface, causing the broken ice layer to detach from the fins. This achieves bending fin vibration defrosting, which has the advantages of faster defrosting speed and better defrosting effect compared to ordinary defrosting methods.
[0024] This invention uses electromagnetic force to cause the fins to vibrate. Compared with contact vibration generating devices, the vibration generating system of this invention is simple and reliable.
[0025] In order to make the fins vibrate, the electromagnet only needs to be connected to the power supply for a short time to generate a magnetic field. The electromagnet consumes very little energy and has energy-saving characteristics.
[0026] The composite material fins of the present invention use a non-magnetic metal with good heat transfer performance in the part connected to the heat transfer tube, which can ensure good heat transfer effect of the fins; and use permanent magnet material in the part away from the heat transfer tube, which can ensure that the electromagnetic vibration torque on the fins is maximized, making the fins easy to produce displacement opposite to the initial bending direction.
[0027] The fins of this invention can be straight or curved. Curved fins are more easily excited by external forces to vibrate, and the vibration amplitude is larger, compared to straight fins. At the same time, using opposite initial bending directions between adjacent tubes can cause the fins between adjacent tubes to vibrate in opposite directions. This design can avoid the problem of the entire heat exchanger vibrating when all fins have the same initial bending direction. Attached Figure Description
[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments.
[0029] Figure 1 This is a schematic diagram of the defrosting device for the heat exchanger fins in Example 1.
[0030] Figure 2 This is a schematic diagram of the fin structure in Example 1.
[0031] Figure 3 This is a schematic diagram showing the relative positions of the magnetic poles of the finned permanent magnet material in Example 1.
[0032] Figure 4 This is a schematic diagram of the defrosting device for the heat exchanger fins in Example 2.
[0033] Figure 5 This is a schematic diagram of the fin structure in Example 2.
[0034] Figure 6 This is a schematic diagram showing the relative positions of the magnetic poles of the finned permanent magnet material in Example 2.
[0035] Figure 7 This is a schematic diagram of the non-magnetic metal portion of the fins in Examples 1 and 2.
[0036] Figure 8 This is a schematic diagram of the flat fin structure in Example 1.
[0037] Figure 9 This is a schematic diagram of the curved fins laid flat structure in Example 2.
[0038] Figure 10 This is a schematic diagram of the connection structure between the bent fins and the heat transfer tube in Example 2.
[0039] In the attached image:
[0040] 1. Finned heat exchanger; 2. Fins; 3. Power control box
[0041] 4. Frost detector 5. Displacement detector 6. Heat transfer tube
[0042] 7. Electromagnet 8. Non-magnetic metal part 9. Permanent magnet material part
[0043] 10. Mounting hole; 11. North pole; 12. South pole Detailed Implementation
[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0045] Example 1
[0046] like Figure 1 As shown, a heat exchanger fin defrosting device includes a finned heat exchanger 1, which has multiple sets of fins 2. The fins 2 are evenly provided with mounting holes 10. Heat transfer tubes 6 pass through the mounting holes 10 and are cross-fixed to the multiple sets of fins 2. Electromagnets 7 are installed at both ends of the finned heat exchanger 1, located at the left and right ends of the fin 2. The two sets of electromagnets 7 are powered by a DC power supply with a controller in a power control box 3. A portion of the fins 2 is made of permanent magnet material. Frost detectors 4 and displacement detectors 5 are installed on the fins. The signals detected by the frost detectors 4 and displacement detectors 5 are sent to the controller in the power control box 3 to control the DC power supply to the two sets of electromagnets 7.
[0047] like Figure 2 As shown, the connection between the fin 2 and the heat transfer tube 6 is a non-magnetic metal part 8, and the part of the fin 2 away from the heat transfer tube 6 is a permanent magnet material part 9.
[0048] like Figure 3 As shown, the permanent magnet material portion 9 includes an N pole 11 and an S pole 12. The relative positions of the N pole 11 and S pole 12 of the permanent magnet material portions 9 of the left and right adjacent fins 2 are the same, while the relative positions of the N pole 11 and S pole 12 of the permanent magnet material portions 9 of the upper and lower adjacent fins 2 are opposite.
[0049] In this embodiment, the fin 2 is a curved wavy fin, and the crests and troughs of the fin 2 are permanent magnet material portions 9, which are provided with magnetic strips of permanent magnet material. The material connecting the crests and troughs is a non-magnetic metal portion.
[0050] The permanent magnet material part 9 is made of one of neodymium iron boron, aluminum nickel cobalt, and ferrite. In this embodiment, the permanent magnet material part 9 is made of neodymium iron boron magnet.
[0051] The non-magnetic metal part 8 is made of one of aluminum, aluminum alloy, or copper. In this embodiment, the non-magnetic metal part 8 is made of aluminum alloy.
[0052] The defrosting method of the heat exchanger fin defrosting device includes the following steps:
[0053] A. During the operation of the finned heat exchanger 1, when the frost detector 4 detects ice on the surface of the fins 2, the controller in the power control box 3 connects the DC power supply to the circuit of the electromagnet 7, and the electromagnet 7 generates an electromagnetic field.
[0054] B. The electromagnetic field acts on the permanent magnet material part 9 of the fin 2, generating a force opposite to the initial bending direction of the fin 2, causing the fin 2 to bend in the opposite direction to the initial bending direction. During this process, the work done by the electromagnetic force on the magnetic strip is stored in the fin 2.
[0055] C. When the displacement detector 5 detects the displacement of the fin 2, the controller disconnects the DC power supply from the circuit of the electromagnet 7, the electromagnetic field of the electromagnet 7 disappears, and the electromagnetic force between the electromagnet 7 and the fin 2 disappears.
[0056] D. Fin 2, which is not subject to electromagnetic force, vibrates under the action of elastic force. The vibration will cause the ice layer on the surface of fin 2 to break and fall off.
[0057] E. After the ice layer falls off, the vibration of fin 2 gradually stops, fin 2 returns to its initial state, and the surface defrosting of fin 2 is completed;
[0058] F. Frost forms again on the surface of fin 2, and the above AE process restarts, realizing the frost formation and defrosting cycle on the surface of heat exchanger fin 2.
[0059] Example 2
[0060] like Figure 4 As shown, a heat exchanger fin defrosting device includes a finned heat exchanger 1, which has multiple sets of fins 2. The fins 2 are evenly provided with mounting holes 10. Heat transfer tubes 6 pass through the mounting holes 10 and are cross-fixed to the multiple sets of fins 2. Electromagnets 7 are installed at both ends of the finned heat exchanger 1, located at the left and right ends of the fin 2. The two sets of electromagnets 7 are powered by a DC power supply with a controller in a power control box 3. A portion of the fins 2 is made of permanent magnet material. Frost detectors 4 and displacement detectors 5 are installed on the fins. The signals detected by the frost detectors 4 and displacement detectors 5 are sent to the controller in the power control box 3 to control the DC power supply to the two sets of electromagnets 7.
[0061] like Figure 5 As shown, the connection between the fin 2 and the heat transfer tube 6 is a non-magnetic metal part 8, and the part of the fin 2 away from the heat transfer tube 6 is a permanent magnet material part 9.
[0062] like Figure 6 As shown, the permanent magnet material portion 9 includes an N pole 11 and an S pole 12. The relative positions of the N pole 11 and S pole 12 of the permanent magnet material portions 9 of the left and right adjacent fins 2 are the same, while the relative positions of the N pole 11 and S pole 12 of the permanent magnet material portions 9 of the upper and lower adjacent fins 2 are opposite.
[0063] In this embodiment, fin 2 is a straight fin.
[0064] The permanent magnet material part 9 is made of one of neodymium iron boron, aluminum nickel cobalt, and ferrite. In this embodiment, the permanent magnet material part 9 is made of aluminum nickel cobalt magnet.
[0065] The non-magnetic metal part 8 is made of one of aluminum, aluminum alloy, or copper. In this embodiment, the non-magnetic metal part 8 is made of aluminum.
[0066] The defrosting method of the heat exchanger fin defrosting device includes the following steps:
[0067] A. During the operation of the finned heat exchanger 1, when the frost detector 4 detects ice on the surface of the fins 2, the controller in the power control box 3 connects the DC power supply to the circuit of the electromagnet 7, and the electromagnet 7 generates an electromagnetic field.
[0068] B. The electromagnetic field acts on the permanent magnet material part 9 of the fin 2, forming a bending angle. During this process, the work done by the electromagnetic force on the magnetic strip is stored in the fin 2.
[0069] C. When the displacement detector 5 detects the displacement of the fin 2, the controller disconnects the DC power supply from the circuit of the electromagnet 7, the electromagnetic field of the electromagnet 7 disappears, and the electromagnetic force between the electromagnet 7 and the fin 2 disappears.
[0070] D. Fin 2, which is not subject to electromagnetic force, vibrates under the action of elastic force. The vibration will cause the ice layer on the surface of fin 2 to break and fall off.
[0071] E. After the ice layer falls off, the vibration of fin 2 gradually stops, fin 2 returns to its initial state, and the surface defrosting of fin 2 is completed;
[0072] F. Frost forms again on the surface of fin 2, and the above AE process restarts, realizing the frost formation and defrosting cycle on the surface of heat exchanger fin 2.
[0073] In step B, fin 2 is a curved wavy fin. The electromagnetic field acts on the magnetic strips of the permanent magnet material part 9 at the crests and troughs of fin 2, generating a force opposite to the initial bending direction of fin 2, causing fin 2 to bend in the opposite direction to the initial bending direction. During this process, the work done by the electromagnetic force on the magnetic strips is stored in fin 2.
[0074] Example 3
[0075] In Examples 1 and 2, the processing and installation methods of the fins 2 and the heat transfer tube 6 are as follows:
[0076] 1. A unit made of non-magnetic metal, with fins 2 connected to heat transfer tubes 6.
[0077] A non-magnetic metal with good heat transfer properties is cut into rectangular metal plates of suitable size. Holes are then drilled at appropriate locations on the metal plates for connection to heat transfer tube 6. The completed non-magnetic metal plate is shown below. Figure 7 As shown.
[0078] 2. The magnetic induction unit of fin 6 is made of permanent magnet material.
[0079] Permanent magnet materials with good magnetic properties are made into rectangular magnetic strips with the same thickness and length as non-magnetic metal plates and with appropriate width.
[0080] 3. Connect the non-magnetic metal plate to the magnetic strip.
[0081] Using material joining methods, such as low-temperature welding, non-magnetic metal plates and magnetic strips are connected along their length. Multiple non-magnetic metal plates and magnetic strips are connected to form fins, such as... Figure 8 As shown, Figure 8 The center consists of four non-magnetic metal plates connected to three magnetic strips to form a straight fin.
[0082] 4. Making curved fins
[0083] Using mechanical processing methods, such as bottom die bending, the straight fins 2 are bent around each magnetic strip to obtain curved fins 2, such as... Figure 9 As shown.
[0084] 5. Pass the heat transfer tubes 6 of the heat exchanger through the mounting holes 10 of the fins 2, and use tube expansion or welding methods to make a reliable connection between the fins and the heat transfer tubes, thus completing the fabrication of the heat exchanger. Figure 10 As shown.
Claims
1. A defrosting device for a finned heat exchanger, comprising a finned heat exchanger (1), characterized in that: The finned heat exchanger (1) is equipped with multiple sets of fins (2). The fins (2) are evenly provided with mounting holes (10). The heat transfer tube (6) passes through the mounting holes (10) and is cross-fixed to the multiple sets of fins (2). Electromagnets (7) are installed at both ends of the finned heat exchanger (1). The electromagnets (7) are located at the left and right ends of the fin (2) as a whole. The two sets of electromagnets (7) are powered by a DC power supply with a controller in the power control box (3). A part of the fin (2) is made of permanent magnet material. Frost detectors (4) and displacement detectors (5) are provided on the fins. The signals detected by the frost detectors (4) and displacement detectors (5) are sent to the controller in the power control box (3) to control the DC power supply to the two sets of electromagnets (7).
2. The heat exchanger fin defrosting device according to claim 1, characterized in that: The connection between the fin (2) and the heat transfer tube (6) is a non-magnetic metal part (8), and the part of the fin (2) away from the heat transfer tube (6) is a permanent magnet material part (9).
3. The heat exchanger fin defrosting device according to claim 2, characterized in that: The permanent magnet material part (9) includes an N pole (11) and an S pole (12). The relative positions of the N pole (11) and S pole (12) of the permanent magnet material part (9) of the left and right adjacent fins (2) are the same, while the relative positions of the N pole (11) and S pole (12) of the permanent magnet material part (9) of the upper and lower adjacent fins (2) are opposite.
4. The heat exchanger fin defrosting device according to claim 2, characterized in that: The fin (2) is a straight fin.
5. The heat exchanger fin defrosting device according to claim 2, characterized in that: The fin (2) is a curved wavy fin, and the peaks and troughs of the fin (2) are permanent magnet material parts (9), while the material connecting the peaks and troughs is a non-magnetic metal part (8).
6. The heat exchanger fin defrosting device according to claim 2, characterized in that: The permanent magnet material (9) is made of one of neodymium iron boron, aluminum nickel cobalt, or ferrite.
7. The heat exchanger fin defrosting device according to claim 2, characterized in that: The material of the non-magnetic metal part (8) is one of aluminum, aluminum alloy, or copper.
8. The defrosting method of the heat exchanger fin defrosting device according to claim 4 or claim 5, characterized by, Includes the following steps: A. During the operation of the finned heat exchanger (1), when the frost detector (4) detects ice on the surface of the fins (2), the controller in the power control box (3) connects the DC power supply to the circuit of the electromagnet (7), and the electromagnet (7) generates an electromagnetic field. B. The electromagnetic field acts on the permanent magnet material part (9) of the fin (2) to form a bending angle. During this process, the work done by the electromagnetic force on the magnetic strip is stored in the fin (2). C. When the displacement detector (5) detects the displacement of the fin (2), the controller disconnects the DC power supply from the electromagnet (7), the electromagnetic field of the electromagnet (7) disappears, and the electromagnetic force between the electromagnet (7) and the fin (2) disappears. D. The fin (2) which is not subject to electromagnetic force will vibrate under the action of elastic force. The vibration will cause the ice layer on the surface of the fin (2) to break and fall off. E. After the ice layer falls off, the vibration of the fin (2) gradually stops, the fin (2) returns to its initial state, and the surface defrosting of the fin (2) is completed; F. Frost forms again on the surface of the fins (2), and the above AE process restarts to achieve the frost formation and defrosting cycle on the surface of the heat exchanger fins (2).
9. The defrosting method of the heat exchanger fin defrosting device according to claim 8, characterized by: In step B, the fin (2) is a curved wavy fin. The electromagnetic field acts on the permanent magnet material part (9) at the crest and trough of the fin (2), generating a force opposite to the initial bending direction of the fin (2), causing the fin (2) to bend in the opposite direction to the initial bending direction. During this process, the work done by the electromagnetic force on the magnetic strip is stored in the fin (2).