Heat pump unit with heat recovery system and control method

Abstract

The invention relates to the technical field of heat pumps, in particular to a heat pump unit with a heat recovery system and a control method.The heat pump unit comprises a compressor, a four-way valve, a main heat exchanger, an evaporator, a gas-liquid separator, an auxiliary heat exchanger and a defrosting coil pipe; a refrigerant inlet and a refrigerant outlet of the auxiliary heat exchanger are connected to a pipeline connected between the outlet of the compressor and the four-way valve through pipelines, and electromagnetic valves are arranged at the refrigerant inlet and the refrigerant outlet of the auxiliary heat exchanger; the defrosting coil pipe is arranged on one side of the evaporator, the two ends of the defrosting coil pipe are connected with a water inlet and a water outlet of the auxiliary heat exchanger through hoses respectively, and the defrosting coil pipe comprises a plurality of heat conduction sections distributed in the length direction of the evaporator and transition sections used for connecting the heat conduction sections end to end. The auxiliary heat exchanger is arranged at the outlet of the compressor in parallel and used for heating by utilizing redundant heat of a high-temperature refrigerant, so that the purpose of heat recovery is achieved, and the energy utilization rate of the heat pump unit is improved.

Description

Technical Field

[0001] This invention relates to the field of heat pump technology, specifically to a heat pump unit with a heat recovery system and its control method. Background Technology

[0002] Existing heat pump units have many technical problems in actual operation, such as unreasonable energy utilization and high energy consumption, which limit their energy-saving efficiency and do not meet the current development needs of energy conservation, emission reduction and carbon neutrality.

[0003] Specifically, when a user's heat source demand is low during heating operation, existing heat pump units can only reduce heating capacity by lowering the compressor's frequency. This adjustment method not only affects the unit's operational stability but also leads to insufficient energy utilization. Furthermore, when switching to cooling mode in summer, a large amount of waste heat is generated on the unit's condenser side. Current technology does not effectively recover and utilize this waste heat, resulting in its direct release into the air. This daily heat loss causes significant energy waste and reduces the overall energy efficiency of the unit.

[0004] Furthermore, under low-temperature heating conditions in winter, when the ambient humidity is high, the fins of the heat pump unit's evaporator are prone to frost formation. This frost layer hinders the heat exchange process and reduces heating efficiency. To ensure normal unit operation, the compressor needs to allocate some heat for defrosting periodically. This process not only interrupts normal heating supply but also consumes a significant amount of additional energy, further increasing the heat pump unit's energy consumption. Therefore, existing residential and commercial heat pump units suffer from defrosting and high energy consumption due to insufficient heat recovery. To address these shortcomings, we propose a heat pump unit with a heat recovery system and its control method. Summary of the Invention

[0005] The purpose of this invention is to provide a heat pump unit with a heat recovery system and a control method thereon, in order to solve the problems mentioned in the background art.

[0006] This invention is achieved through the following technical solution: a heat pump unit with a heat recovery system, comprising a compressor, a four-way valve, a main heat exchanger, an evaporator, and a gas-liquid separator, and further comprising: The auxiliary heat exchanger has its refrigerant inlet and outlet connected to the pipeline between the compressor outlet and the four-way valve via pipelines, and both the refrigerant inlet and outlet of the auxiliary heat exchanger are equipped with solenoid valves. The defrosting coil is located on one side of the evaporator, and its two ends are connected to the inlet and outlet of the auxiliary heat exchanger via flexible hoses. The defrosting coil includes several heat-conducting sections distributed along the length of the evaporator and a transition section for connecting the ends of the heat-conducting sections. A driving mechanism is provided on the evaporator and is used to drive the defrosting coil to translate along the height and width directions of the evaporator. The evaporator includes several fins evenly spaced along its length. Each fin has several rows of through holes spaced along its height for heat-conducting copper tubes to pass through. Each fin also has several heat-conducting notches on the side facing the defrost coil. The heat-conducting notches on each fin correspond one-to-one with several heat-conducting sections in the defrost coil. The heat-conducting notches are located between two adjacent rows of through holes. The driving mechanism can drive the heat-conducting sections of the defrost coil to enter or leave the heat-conducting notches.

[0007] Optionally, the drive mechanism includes two extension plates mounted on the left and right sides of the evaporator. The surfaces of the extension plates are provided with slide rails, and displacement blocks slide on the slide rails. Each displacement block has a U-shaped structure, with a slider sliding along the width of the evaporator on its inner side. The left and right sides of the defrost coil are fixedly connected to the two sliders respectively. The number of displacement blocks on the extension plates matches the number of heat-conducting sections of the defrost coil. The defrost coil is made of copper, and the transition section of the defrost coil is wrapped with a heat-insulating sleeve.

[0008] Optionally, a drive cylinder is provided on the outer side of the extension platform, and the movable end of the drive cylinder is fixedly connected to the displacement block through a connector; an electromagnet is provided at the inner end of the displacement block, and a permanent magnet is fixedly embedded at the end of the slider facing the electromagnet. When the electromagnet is energized, the opposing magnetic poles of the electromagnet and the permanent magnet are the same. The width of the heat-conducting notch matches the diameter of the defrosting coil, the inner end of the heat-conducting notch is an arc shape that matches the outer contour of the defrosting coil, and the inner end of the heat-conducting notch is located at half the width of the fin.

[0009] Optionally, heat-conducting plates are slidably provided on both sides of the inner side of the heat-conducting notch along the height direction. The heat-conducting plates and fins are slidably attached to each other along the height direction, and the outer sides of the opposing ends of the two heat-conducting plates in the same heat-conducting notch are in an inwardly concave arc shape. Several thin rods are provided on the outer side of the fins along the horizontal direction. The number of thin rods corresponds to the number of heat-conducting plates on the same fin, and the heat-conducting plates at the same height are all fixedly connected to the same thin rod.

[0010] Optionally, the heat-conducting plate is a double-layered thin copper sheet, with its two sides respectively attached to the two sides of the fins. The surface of the fins, and on both sides of the heat-conducting notch, has protrusions distributed along the height direction. The heat-conducting plate has grooves that match the protrusions, and the protrusions are embedded in the grooves. Retaining plates are fixedly provided on both sides of the evaporator. Several waist-shaped grooves, corresponding one-to-one with the thin rods, are formed on the retaining plates along the height direction. The ends of the thin rods pass through the waist-shaped grooves, and an elastic rope connects the two thin rods connected to the two heat-conducting plates located in the same heat-conducting notch. In its natural state, the elastic rope is taut.

[0011] The present invention also proposes a control method for a heat pump unit with a heat recovery system, applicable to the above-mentioned heat pump unit, comprising the following steps: When excess heat is generated in the unit system, the solenoid valves at the inlet and outlet of the auxiliary heat exchanger are opened to allow high-temperature refrigerant to enter the auxiliary heat exchanger, thereby heating the water inside the auxiliary heat exchanger. When frost forms on the surface of the evaporator, hot water is introduced into the defrost coil. Then, the movement of the defrosting coil is controlled by the drive mechanism so that the heat-conducting section of the defrosting coil comes into contact with the fins of the evaporator. After the defrosting process is completed, the defrosting coil and fins are separated by the drive mechanism.

[0012] Compared with the prior art, the present invention provides a heat pump unit with a heat recovery system and a control method, which has the following beneficial effects: 1. The present invention sets up an auxiliary heat exchanger in parallel at the outlet of the compressor. Its function is to use the excess heat of the high-temperature refrigerant to generate heat, thereby achieving the purpose of heat recovery, which helps to improve the energy utilization rate of the heat pump unit. 2. This invention uses hot water generated by the auxiliary heat exchanger to heat the fins of the evaporator, thereby achieving the purpose of defrosting. Furthermore, it does not consume the high-temperature refrigerant at the compressor outlet during defrosting, thus achieving energy saving without affecting the indoor heating effect. 3. The defrosting coil in this invention is movable. In non-defrosting conditions, the defrosting coil can avoid increasing wind resistance as much as possible, while in defrosting conditions, the defrosting coil can be deeply fitted with the fins, thereby improving defrosting uniformity and defrosting efficiency. 4. The fins in this invention have heat-conducting notches for the defrosting coil to be inserted, and heat-conducting plates are movably arranged inside the heat-conducting notches. Under non-defrosting conditions, the heat-conducting plates can block the heat-conducting notches, thereby keeping the surface area of ​​the fins unchanged and avoiding affecting the heat exchange efficiency of the evaporator. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2This is a schematic diagram of the chassis structure of the present invention; Figure 3 This is a front view of the evaporator structure of the present invention; Figure 4 This is a front view of the evaporator of the present invention in another state; Figure 5 This is a schematic diagram of the defrosting coil structure of the present invention; Figure 6 This is a partial schematic diagram of the defrosting coil of the present invention; Figure 7 This is a schematic diagram of the fin structure of the present invention; Figure 8 This is a front view of the fin structure of the present invention; Figure 9 This is a schematic diagram of the fin stacking state of the present invention; Figure 10 This is a schematic diagram of the heat-conducting sheet structure of the present invention; Figure 11 This is a schematic diagram of the thin rod structure of the present invention; Figure 12 for Figure 6 Enlarged view of point A in the middle; Figure 13 for Figure 11 Enlarged view of the corresponding area at point B.

[0014] In the diagram: 100, compressor; 200, main heat exchanger; 300, evaporator; 301, fins; 302, through hole; 303, heat conduction notch; 304, heat conduction plate; 305, thin rod; 306, protruding rib; 307, groove; 308, retaining plate; 309, waist-shaped groove; 310, elastic rope; 400, auxiliary heat exchanger; 500, defrosting coil; 600, drive mechanism; 601, extension platform; 602, slide rail; 603, displacement block; 604, slider; 605, drive electric cylinder; 606, electromagnet. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Example 1: Please refer to Figure 1 - Figure 13This application proposes a heat pump unit with a heat recovery system, including a compressor 100, a four-way valve, a main heat exchanger 200, an evaporator 300, and a gas-liquid separator. It also includes a secondary heat exchanger 400, a defrost coil 500, and a drive mechanism 600. The refrigerant inlet and outlet of the secondary heat exchanger 400 are connected via pipelines to the pipeline connecting the outlet of the compressor 100 and the four-way valve. Solenoid valves are installed at both the refrigerant inlet and outlet of the secondary heat exchanger 400. When the secondary heat exchanger 400 is not in use, the solenoid valves are always closed. When the solenoid valves open, high-temperature refrigerant enters the secondary heat exchanger 400, thereby heating the water inside the secondary heat exchanger and achieving heat recovery. It is worth noting that the secondary heat exchanger 400 is a shell-and-tube heat exchanger.

[0017] Taking winter heating mode as an example, when the user's demand for heat decreases, the solenoid valves at both the inlet and outlet of the auxiliary heat exchanger 400 open, allowing high-temperature refrigerant to enter the auxiliary heat exchanger 400. Simultaneously, the compressor frequency is reduced, thereby rapidly decreasing the heat supply to the user and utilizing excess heat to heat the water within the auxiliary heat exchanger 400. The same principle applies to cooling mode. Under normal operating conditions, the solenoid valves are normally closed. When excess heat occurs in the unit system, it is discharged to the auxiliary heat exchanger 400, thus achieving heat recovery and improving energy efficiency.

[0018] In this embodiment, the defrosting coil 500 is disposed on one side of the evaporator 300, with its two ends connected to the inlet and outlet of the auxiliary heat exchanger 400 via flexible hoses. The defrosting coil 500 includes several heat-conducting sections distributed along the length of the evaporator 300 and transition sections connecting the ends of the heat-conducting sections. The driving mechanism 600 is disposed on the evaporator 300 and is used to drive the defrosting coil 500 to translate along the height and width directions of the evaporator 300. It should be noted that both ends of the defrosting coil 500 are also equipped with solenoid valves, which are normally closed when defrosting is not required. A miniature water pump is also provided on the pipeline connecting the defrosting coil 500 and the auxiliary heat exchanger 400. Its function is to drive water circulation, so that the warm water inside the auxiliary heat exchanger 400 can circulate into the defrosting coil 500, thereby facilitating defrosting of the evaporator 300.

[0019] Furthermore, the defrost coil 500 is S-shaped and made of copper. Its heat-conducting section is parallel to the heat-conducting copper pipe inside the evaporator 300. The transition section of the defrost coil 500 is wrapped with a heat-insulating sleeve made of plastic or insulating cotton. It is worth noting that since the evaporator 300 constantly needs to exchange heat with the air, the presence of the defrost coil 500 will inevitably increase air resistance. Therefore, to minimize air resistance, in this embodiment, when not defrosting, its heat-conducting section and the heat-conducting copper pipe of the evaporator 300 are kept at the same horizontal level. Figure 3The state shown is such that the air resistance of the evaporator 300 is reduced as much as possible.

[0020] The evaporator 300 includes several fins 301 evenly spaced along its length. Each fin 301 has rows of through holes 302 spaced along its height for heat-conducting copper tubes to pass through. Several heat-conducting notches 303 are also provided on the side of the fins facing the defrost coil 500. Each heat-conducting notch 303 on each fin 301 corresponds one-to-one with several heat-conducting sections in the defrost coil 500. The heat-conducting notches 303 are located between adjacent rows of through holes 302. The driving mechanism 600 can drive the heat-conducting sections of the defrost coil 500 into or out of the heat-conducting notches 303. Figure 7 As shown, a heat-conducting notch 303 is not made between every two adjacent rows of through holes 302, but rather every few rows of through holes 302. This is because the fins 301 are made of copper, which has good thermal conductivity, so there is no need to make too many heat-conducting notches 303. Moreover, the more heat-conducting notches 303 there are, the smaller the surface area of ​​the fins 301 becomes, which is less conducive to heat exchange between the fins 301 and the air.

[0021] As one embodiment and not a limitation, the drive mechanism 600 includes two extension plates 601 mounted on the left and right sides of the evaporator 300. The surface of each extension plate 601 is provided with a slide rail 602, and a displacement block 603 is slidably mounted on the slide rail 602. The displacement block 603 has a U-shaped structure, and a slider 604 is slidably mounted on its inner side along the width direction of the evaporator 300. The left and right sides of the defrost coil 500 are fixedly connected to the two sliders 604 respectively. The number of displacement blocks 603 on the extension plate 601 matches the number of heat-conducting sections of the defrost coil 500. The extension plate 601 is a rectangular plate-shaped aluminum alloy structure, bolted to the outer frame of the evaporator 300. The slide rail 602 is distributed along the height direction, that is, along the length direction of the fins 301. When the displacement block 603 slides along the slide rail 602, it drives the defrost coil 500 to move synchronously.

[0022] Furthermore, a drive cylinder 605 is provided on the outer side of the extension platform 601. The movable end of the drive cylinder 605 is fixedly connected to the displacement block 603 via a connector. The drive cylinder 605 is distributed along the height direction and can directly drive the defrost coil 500 to move along the height direction. An electromagnet 606 is provided at the inner end of the displacement block 603. A permanent magnet is fixedly embedded at the end of the slider 604 opposite to the electromagnet 606. When the electromagnet 606 is energized, the opposing magnetic poles of the electromagnet 606 and the permanent magnet are the same. When the electromagnet 606 is de-energized, the electromagnet 606 is equivalent to an iron block. At this time, the permanent magnet and the electromagnet 606 attract each other, so that the defrost coil 500 is close to the fin 301. Conversely, when the electromagnet 606 is energized, the defrost coil 500 can move away from the fin 301 under the action of magnetic pole repulsion. It should be noted that the heat-conducting section and the transition section of the defrosting coil 500 are not in the same vertical plane; the heat-conducting section is the one closest to the fins 301. When the drive cylinder 605 aligns the heat-conducting section of the defrosting coil 500 with the heat-conducting notch 303, and the electromagnet 606 is de-energized, the heat-conducting section of the defrosting coil 500 can smoothly embed itself into the heat-conducting notch 303. Figure 4 As shown in the figure; when the electromagnet 606 is energized, the heat-conducting section can be moved out of the heat-conducting notch 303.

[0023] As one embodiment and not a limitation, the width of the heat-conducting notch 303 matches the diameter of the defrosting coil 500, the inner end of the heat-conducting notch 303 is an arc shape matching the outer contour of the defrosting coil 500, and the inner end of the heat-conducting notch 303 is located at half the width of the fin 301. Therefore, when the heat-conducting section of the defrosting coil 500 enters the inner end of the heat-conducting notch 303, since the inner end of the heat-conducting notch 303 is located at half the width of the fin 301, the heat of the defrosting coil 500 can be transferred to the fin 301 more evenly, thereby improving defrosting efficiency.

[0024] In some embodiments of this application, heat-conducting plates 304 are slidably provided on both sides of the inner side of the heat-conducting notch 303 along the height direction. The heat-conducting plates 304 and the fins 301 are slidably attached to each other along the height direction, and the outer sides of the opposing ends of the two heat-conducting plates 304 within the same heat-conducting notch 303 are concave in an arc shape. A plurality of thin rods 305 are provided on the outer side of the fins 301 along the horizontal direction. The number of thin rods 305 corresponds to the number of heat-conducting plates 304 on the same fin 301, and the heat-conducting plates 304 located at the same height are all fixedly connected to the same thin rod 305. One corner of the heat-conducting plate 304 is rounded, such as... Figure 10As shown, its function is to force the defrosting coil 500 to push apart the heat-conducting fins 304. The thin rod 305 connects all the heat-conducting fins 304 at the same height on all the fins 301 into one unit. Specifically, the thin rod 305 and the heat-conducting fins 304 can be fixed by welding. Furthermore, the diameter of the thin rod 305 does not exceed 5mm, its function being to minimize air resistance. Simultaneously, the purpose of the heat-conducting fins 304 is to seal the heat-conducting gaps 303 when not defrosting, thereby maintaining the surface area of ​​the fins 301 and preventing the opening of the heat-conducting gaps 303 from affecting the heat exchange efficiency of the evaporator 300.

[0025] Furthermore, the heat-conducting sheet 304 is a double-layered thin copper sheet, with its two sides respectively attached to the two sides of the fin 301. The surface of the fin 301, located on both sides of the heat-conducting notch 303, has raised ribs 306 distributed along the height direction. The heat-conducting sheet 304 has grooves that match the raised ribs 306, with the raised ribs 306 embedded in the grooves. The raised ribs 306 are formed by stamping and bending, and the grooves 307 are also formed by stamping. The two work together to allow the heat-conducting sheet 304 to slide along the height direction, while increasing the fit between them, thus improving heat conduction. When two heat-conducting sheets 304 within the same heat-conducting notch 303 are attached, such as... Figure 9 As shown, the heat-conducting notch 303 is closed at this time to increase the heat exchange area of ​​the fin 301. It should be noted that the presence of several heat-conducting notches 303 on a single fin 301 significantly reduces the surface area of ​​the fin 301, thereby reducing the total heat exchange capacity of the fin 301. Furthermore, due to the large number of fins 301, this also affects the heat exchange efficiency of the evaporator 300. To balance the heat exchange efficiency of the evaporator 300, the heat-conducting plate 304 in this embodiment is tightly slidably attached to the fin 301, so that the surface area of ​​the fin 301 remains constant, thus preventing the heat exchange efficiency of the evaporator 300 from being affected under non-defrosting conditions.

[0026] In this embodiment, retaining plates 308 are fixedly provided on both sides of the evaporator 300. Several waist-shaped grooves 309, corresponding one-to-one with the thin rods 305, are formed on the retaining plates 308 along the height direction. The ends of the thin rods 305 pass through the waist-shaped grooves 309, and an elastic rope 310 connects the two thin rods 305 that are connected to two heat-conducting plates 304 located within the same heat-conducting notch 303. In the natural state, the elastic rope 310 is taut. The waist-shaped grooves 309 are used to limit the sliding range of the heat-conducting plates 304, so that in the natural state, under the pulling action of the elastic rope 310, the thin rods 305 all abut against one end of the inside of the waist-shaped groove 309, and the two heat-conducting plates 304 within the same heat-conducting notch 303 can maintain a symmetrical distribution, that is, the contact surfaces of the two heat-conducting plates 304 are aligned with the center line of the heat-conducting notch 303. It is worth mentioning that the reason for embedding the defrosting coil 500 into the center of the fin 301 is to allow the heat from the defrosting coil 500 to be transferred to the fin 301 more evenly, thereby improving its defrosting efficiency.

[0027] Example 2: This application also proposes a control method for a heat pump unit with a heat recovery system, applicable to the heat pump unit in Example 1 above, including the following steps: When excess heat is generated in the unit system, the solenoid valves at the inlet and outlet of the auxiliary heat exchanger 400 are opened to allow high-temperature refrigerant to enter the auxiliary heat exchanger 400, thereby heating the water inside the auxiliary heat exchanger 400. When frost appears on the surface of the evaporator 300, hot water is introduced into the defrost coil 500. When the hot water circulates inside the defrost coil 500, it can rapidly heat up the defrost coil 500. Then, the defrosting coil 500 is moved by the drive mechanism 600 so that the heat-conducting section of the defrosting coil 500 comes into contact with the fins 301 of the evaporator 300. Specifically, the drive cylinder 605 controls the defrosting coil 500 to move horizontally so that the heat-conducting section and the heat-conducting notch 303 are aligned. Then, the electromagnet 606 is de-energized, so that the defrosting coil 500 moves closer to the inner end of the heat-conducting notch 303 and pushes apart the two heat-conducting fins 304. When the defrosting coil 500 is embedded in the inner side of the fins 301, heat can be continuously transferred to the fins 301, thereby defrosting them.

[0028] After the defrosting process is completed, the drive mechanism 600 controls the defrosting coil 500 and the fins 301 to separate. Specifically, the electromagnet 606 is re-energized, causing the defrosting coil 500 to move away from the heat conduction gap 303. Then, the drive cylinder 605 controls the defrosting coil 500 to move horizontally, aligning its heat conduction section with the heat conduction copper tube of the evaporator 300. This avoids increasing the wind resistance coefficient of the evaporator 300 and ensures that the heat exchange process is smooth and efficient.

[0029] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0030] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A heat pump unit with a heat recovery system, comprising a compressor, a four-way valve, a main heat exchanger, an evaporator, and a gas-liquid separator, characterized in that, Also includes: The auxiliary heat exchanger has its refrigerant inlet and outlet connected to the pipeline between the compressor outlet and the four-way valve via pipelines, and both the refrigerant inlet and outlet of the auxiliary heat exchanger are equipped with solenoid valves. The defrosting coil is located on one side of the evaporator, and its two ends are connected to the inlet and outlet of the auxiliary heat exchanger via flexible hoses. The defrosting coil includes several heat-conducting sections distributed along the length of the evaporator and a transition section for connecting the ends of the heat-conducting sections. A driving mechanism is provided on the evaporator and is used to drive the defrosting coil to translate along the height and width directions of the evaporator. The evaporator includes several fins evenly spaced along its length. Each fin has several rows of through holes spaced along its height for heat-conducting copper tubes to pass through. Each fin also has several heat-conducting notches on the side facing the defrost coil. The heat-conducting notches on each fin correspond one-to-one with several heat-conducting sections in the defrost coil. The heat-conducting notches are located between two adjacent rows of through holes. The driving mechanism can drive the heat-conducting sections of the defrost coil to enter or leave the heat-conducting notches.

2. A heat pump unit with a heat recovery system according to claim 1, characterized in that: The drive mechanism includes two extension plates installed on the left and right sides of the evaporator. The surface of the extension plates is provided with slide rails, and displacement blocks are slidably provided on the slide rails. The displacement blocks have a U-shaped structure, and sliders are slidably provided on their inner sides along the width direction of the evaporator. The left and right sides of the defrost coil are fixedly connected to the two sliders respectively.

3. A heat pump unit with a heat recovery system according to claim 2, characterized in that: The number of displacement blocks on the extension plate matches the number of heat-conducting sections of the defrosting coil.

4. A heat pump unit with a heat recovery system according to claim 1, characterized in that: The defrosting coil is made of copper, and the transition section of the defrosting coil is wrapped with a heat insulation sleeve.

5. A heat pump unit with a heat recovery system according to claim 2, characterized in that: The outer side of the extension platform is provided with a drive electric cylinder, and the movable end of the drive electric cylinder is fixedly connected to the displacement block through a connector; the inner end of the displacement block is provided with an electromagnet, and a permanent magnet is fixedly embedded at the end of the slider facing the electromagnet. When the electromagnet is energized, the opposing magnetic poles of the electromagnet and the permanent magnet are the same.

6. A heat pump unit with a heat recovery system according to claim 1, characterized in that: The width of the heat-conducting notch matches the diameter of the defrosting coil, the inner end of the heat-conducting notch is an arc shape that matches the outer contour of the defrosting coil, and the inner end of the heat-conducting notch is located at half the width of the fin.

7. A heat pump unit with a heat recovery system according to claim 1, characterized in that: The inner side of the heat-conducting notch is provided with heat-conducting plates on both sides along the height direction. The heat-conducting plates and fins are slidably attached to each other along the height direction, and the outer sides of the opposing ends of the two heat-conducting plates in the same heat-conducting notch are in an inwardly concave arc shape. The outer side of the fin is provided with several thin rods distributed in the horizontal direction. The number of thin rods corresponds to several heat-conducting plates on the same fin, and several heat-conducting plates located at the same height are all fixedly connected to the same thin rod.

8. A heat pump unit with a heat recovery system according to claim 7, characterized in that: The heat-conducting sheet is a double-layered thin copper sheet, with its two sides respectively attached to the two sides of the fin. The surface of the fin and both sides of the heat-conducting notch have protrusions distributed along the height direction. The heat-conducting sheet has grooves that match the protrusions, and the protrusions are embedded in the grooves.

9. A heat pump unit with a heat recovery system according to claim 7, characterized in that: The evaporator is fixedly provided with retaining plates on both sides. Several waist-shaped grooves corresponding to the thin rods are opened on the retaining plates along the height direction. The ends of the thin rods pass through the waist-shaped grooves and are connected to the two thin rods that are connected to the two heat-conducting plates located in the same heat-conducting notch by an elastic rope. In the natural state, the elastic rope is taut.

10. A control method for a heat pump unit with a heat recovery system, applicable to the heat pump unit according to any one of claims 1-9, characterized in that, Includes the following steps: When excess heat is generated in the unit system, the solenoid valves at the inlet and outlet of the auxiliary heat exchanger are opened to allow high-temperature refrigerant to enter the auxiliary heat exchanger, thereby heating the water inside the auxiliary heat exchanger. When frost forms on the surface of the evaporator, hot water is introduced into the defrost coil. Then, the movement of the defrosting coil is controlled by the drive mechanism so that the heat-conducting section of the defrosting coil comes into contact with the fins of the evaporator. After the defrosting process is completed, the defrosting coil and fins are separated by the drive mechanism.

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