Defrosting control system, air conditioner and defrosting control method

Abstract

The present application relates to a defrost control system, an air conditioner, and a defrost control method. The defrost control system includes a double-layer tube-fin heat exchanger and a control system. The double-layer tube-fin heat exchanger includes an inner tube and an outer tube. The inner tube includes an inner tube inlet and an inner tube outlet. The outer tube includes an outer tube inlet and an outer tube outlet. The inner tube inlet is connected to the outer tube inlet. A first three-way valve is provided at the outer tube inlet. The inner tube outlet is connected to the outer tube outlet. A second three-way valve is provided at the outer tube outlet. The inner tube inlet is used to allow high-temperature refrigerant gas to flow in. The inner tube outlet is used to allow low-temperature refrigerant liquid to flow out. The outer tube inlet is used for defrosting liquid or refrigerant to flow in. The outer tube outlet is used for defrosting liquid to flow out. The control system is electrically connected to the first three-way valve and the second three-way valve. In heating operation and when defrosting is required, the control system controls the first three-way valve to turn so that it is blocked between the outer tube inlet and the inner tube inlet. The control system controls the second three-way valve to turn so that it is blocked between the outer tube outlet and the inner tube outlet.

Description

Technical Field

[0001] The present application relates to the field of air-conditioning defrosting, and in particular to a defrosting control system, an air conditioner and a defrosting control method. Background Art

[0002] In the field of air conditioning and heating technology, as people's demands for indoor comfort continue to rise, the heating performance of air conditioners in low-temperature environments has attracted increasing attention. Under low-temperature heating conditions, the refrigerant flowing through the air conditioner's outdoor unit defrost control system is in a low-temperature, low-pressure liquid state, which can easily cause frost on the fin surfaces. Frost can seriously affect the air conditioner's heating efficiency and performance. Therefore, defrost technology has become critical to ensuring stable air conditioner operation.

[0003] Currently, traditional air conditioners commonly use a four-way valve switching method for defrosting. This involves changing the flow direction of the four-way valve, switching the system originally used for heating to a cooling cycle, allowing superheated gas to flow through the fins to achieve defrost. However, during this process, the refrigerant in the user-side defrost control system of the unit changes to a low-temperature, low-pressure state, causing the terminal to enter a cooling state. This defrosting method interrupts the heating function during the defrost period, seriously affecting normal user use, reducing user comfort in cold environments, and failing to meet user needs for continuous and stable heating. Summary of the Invention

[0004] The present application provides a defrost control system to solve the technical problem in the above-mentioned prior art that the heating function is interrupted during the defrost period, which seriously affects the normal use of the user.

[0005] The present invention provides a defrost control system, which includes: a double-layer tube-fin heat exchanger and a control system, wherein the double-layer tube-fin heat exchanger includes an inner tube and an outer tube, the inner tube includes an inner tube inlet and an inner tube outlet, the outer tube includes an outer tube inlet and an outer tube outlet, the inner tube inlet is connected to the outer tube inlet, a first three-way valve is provided at the outer tube inlet, the inner tube outlet is connected to the outer tube outlet, and a second three-way valve is provided at the outer tube outlet; the inner tube inlet is used to allow high-temperature refrigerant gas to flow in; the inner tube outlet is used to allow low-temperature refrigerant liquid to flow out; the outer tube inlet is used for defrosting liquid to flow in; The outer tube outlet is used for the outflow of defrosting liquid or refrigerant; the control system is electrically connected to the first three-way valve and the second three-way valve respectively; under heating conditions and when defrosting is required, the control system controls the first three-way valve to turn so that the first three-way valve is blocked between the outer tube inlet and the inner tube inlet; the control system controls the second three-way valve to turn so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, so that the refrigerant flows in through the inner tube inlet and flows out from the inner tube outlet, and at the same time, the defrosting liquid flows in through the outer tube inlet and flows out from the outer tube outlet.

[0006] The outer tube inlet is connected to the second water pump through a temperature sensing pipeline; the inlet of the temperature sensing pipeline is connected between the second water pump and the user-end heat exchanger; the temperature sensing pipeline is configured to transport the defrost liquid within a preset temperature range to the outer tube inlet.

[0007] In which, the temperature sensing pipeline is provided with a water path temperature sensing package and an electric auxiliary heating device, the water path temperature sensing package is arranged close to the second water pump, the water path temperature sensing package and the electric auxiliary heating device are respectively electrically connected to the control system, when the control system obtains that the temperature value measured by the water path temperature sensing package is less than the preset temperature range, the control system controls the electric auxiliary heating device to turn on to heat the defrost liquid in the temperature sensing pipeline.

[0008] Wherein, the temperature sensing pipeline is provided with a two-way valve, the two-way valve is connected between the electric auxiliary heating device and the water channel temperature sensing package, and the two-way valve is electrically connected to the control system.

[0009] Wherein, the temperature sensing pipeline is provided with a water flow switch, and the water flow switch is used to detect whether there is water flowing through the temperature sensing pipeline, and the water flow switch is electrically connected to the control system.

[0010] The outer pipe outlet is connected to a first water pump, and the first water pump is used to provide the defrost control system with pump pressure for defrosting under heating conditions.

[0011] The present invention also provides an air conditioner, including the above-mentioned defrost control system, and also including: a traditional heat pump unit, the traditional heat pump unit including a compressor and a throttle valve, the inner tube inlet is connected to the compressor, for receiving the inflow of high-temperature refrigerant gas; the inner tube outlet is connected to the throttle valve, for allowing low-temperature refrigerant liquid to flow out.

[0012] The present invention also provides a defrost control method, which uses the above-mentioned defrost control system. The defrost control method includes:

[0013] Under heating conditions, make sure the unit meets the defrosting conditions;

[0014] The control system controls the reversal of the second three-way valve, and the control system controls the reversal of the first three-way valve; the control system first controls the reversal of the second three-way valve so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, and the high-temperature refrigerant gas flows in from the inner tube inlet to maintain the heating condition in the inner tube; then controls the reversal of the first three-way valve so that the first three-way valve is blocked between the outer tube inlet and the inner tube inlet, and the defrost liquid flows in from the outer tube inlet to perform the defrost process in the outer tube.

[0015] The control system controls the reversing of the second three-way valve so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, and high-temperature refrigerant gas flows into the inner tube inlet to maintain the heating condition of the inner tube. After the step, the defrost control method includes:

[0016] The control system controls the second water pump to start;

[0017] When the control system obtains that the temperature value measured by the water channel temperature sensing package is less than the preset temperature range, the control system controls the electric auxiliary heating device to turn on to heat the defrost liquid in the temperature sensing pipeline;

[0018] When the control system obtains that the temperature value measured by the water channel temperature sensing package is greater than or equal to the preset temperature range, the control system controls the electric auxiliary heating device to be turned off.

[0019] Wherein, the defrost control method includes:

[0020] Determining that the defrost exit condition is met, the control system controls the two-way valve to close, the control system controls the first three-way valve to reverse, the control system controls the second three-way valve to reverse, and the control system controls the second water pump to shut down.

[0021] Wherein, after the step of determining that the unit meets the defrost condition under the heating condition, the control system controls the reversal of the second three-way valve so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, and high-temperature refrigerant gas flows into the inner tube inlet, so that the inner tube maintains the heating condition. Before the step, the defrost control method includes:

[0022] The control system controls the two-way valve to open so that the second water pump, the temperature sensing pipeline and the double-tube fin heat exchanger maintain a complete communication state.

[0023] wherein, after the control system controls the two-way valve to open, the control system controls the second three-way valve to switch so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, and high-temperature refrigerant gas flows into the inner tube inlet, so that the inner tube maintains a heating condition, and before the step of:

[0024] The control system receives the detection result of the water flow switch, and executes the next step when the water flow switch detects that water flows through the temperature sensing pipe.

[0025] There is a first time interval between the completion of the step of the control system controlling the switching of the second three-way valve and the start of the step of the control system controlling the switching of the first three-way valve.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] The defrost control system, air conditioner and defrost control method provided by the embodiment of the present application, a double-tube fin heat exchanger and a control system are applied in the defrost control system, the double-tube fin heat exchanger includes an inner tube and an outer tube, the inner tube includes an inner tube inlet and an inner tube outlet, the outer tube includes an outer tube inlet and an outer tube outlet, wherein the inner tube inlet is connected to the outer tube inlet, a first three-way valve is arranged at the outer tube inlet, wherein the inner tube outlet is connected to the outer tube outlet, and a second three-way valve is arranged at the outer tube outlet. It should be pointed out that the inner tube inlet is used for the inflow of high-temperature refrigerant gas, the inner tube outlet is used for the outflow of low-temperature refrigerant liquid, the outer tube inlet is used for the inflow of defrost liquid, and the outer tube outlet is used for the outflow of defrost liquid; under the heating condition, the control system controls the first three The three-way valve is turned so that the first three-way valve is blocked between the outer tube inlet and the inner tube inlet; the control system controls the second three-way valve to turn so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, thereby enabling the refrigerant to flow in through the inner tube inlet and flow out from the inner tube outlet, and at the same time, the defrost liquid flows in through the outer tube inlet and flows out from the outer tube outlet; in this way, when the unit is in heating condition and defrosting is required, it is ensured that the refrigerant flows in the inner tube and the defrost liquid flows in the outer tube, thereby achieving the defrosting process under heating condition at the same time, that is, the air conditioner can heat and defrost at the same time, which can greatly improve the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0030] One or more embodiments are exemplarily illustrated by pictures in the corresponding drawings. These exemplifications do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings are represented as similar elements. Unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0031] Figure 1 A schematic diagram of the structure of the defrost control system provided in an embodiment of the present application applied to an air conditioner;

[0032] Figure 2 This is a structural schematic diagram of a first three-way valve and a second three-way valve installed on a double-tube fin heat exchanger provided in an embodiment of the present application.

[0033] Description of reference numerals:

[0034] 1. Double-tube fin heat exchanger; 11. Inner tube inlet; 12. Inner tube outlet; 13. Outer tube inlet; 14. Outer tube outlet; 15. First three-way valve; 16. Second three-way valve; 2. Temperature sensing pipeline; 3. Second water pump; 4. User-end heat exchanger; 21. Water channel temperature sensing package; 22. Electric auxiliary heating device; 23. Two-way valve; 24. Water flow switch; 5. First water pump; 6. Compressor; 7. Throttle valve; 8. Four-way valve. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] The disclosure below provides many different embodiments or examples for implementing different configurations of the present invention. To simplify the disclosure of the present invention, the components and configurations of specific examples are described below. Of course, these are merely examples and are not intended to limit the present invention. In addition, the present invention may repeat reference numerals and / or letters in different examples. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or configurations discussed.

[0037] For ease of description, spatially relative terms may be used herein to describe the relative position or movement of one element or feature relative to another element or feature as shown in the figures. These relative terms include, for example, "inside," "outside," "inside," "outside," "below," "beneath," "above," "above," "front," "rear," and the like. Such spatially relative terms are intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is flipped, changes position, or changes motion, these directional indications will change accordingly. For example, an element described as "below" or "beneath" another element or feature would subsequently be oriented "above" or "above" the other element or feature. Thus, the example term "below" can encompass both above and below orientations. The device may be oriented differently (rotated 90 degrees or in other orientations), and the spatially relative terms used herein should be interpreted accordingly.

[0038] Currently, traditional air conditioners commonly use a four-way valve switching method for defrosting. This involves changing the flow direction of the four-way valve, switching the system originally used for heating to a cooling cycle, allowing superheated gas to flow through the fins to achieve defrost. However, during this process, the refrigerant in the user-side defrost control system of the unit changes to a low-temperature, low-pressure state, causing the terminal to enter a cooling state. This defrosting method interrupts the heating function during the defrost period, seriously affecting normal user use, reducing user comfort in cold environments, and failing to meet user needs for continuous and stable heating.

[0039] Specifically, in conventional heat pump units, the left side of the user-side heat exchanger carries refrigerant, while the right side carries water. During normal heating, the high-temperature gas refrigerant from the compressor passes through a four-way valve (which connects two of them), flows downward to the user-side heat exchanger to provide heat to the user, then passes through a throttle valve to the fins. From there, it returns to the compressor via the four-way valve, following the black arrow. Cooling or defrosting is achieved by turning the four-way valve. The high-temperature gas refrigerant from the compressor then flows upward through the fins, making a complete circuit, returning to the four-way valve, and finally returning to the compressor.

[0040] During defrosting, the high-temperature gas refrigerant will turn into low-temperature liquid refrigerant after passing through the fins and electronic expansion valve and reach the user end. Therefore, the defrosting process is opposite to the heating process, which will affect the normal heating.

[0041] In order to alleviate the above technical problems, the embodiments of the present application provide a new defrost control system, which is applied to an air conditioner and can realize the defrost process simultaneously under heating conditions.

[0042] refer to Figure 1-Figure 2 The embodiment of the present application provides a new defrost control system, including a double-layer tube-fin heat exchanger 1 and a control system, wherein the double-layer tube-fin heat exchanger 1 includes an inner tube and an outer tube, the inner tube includes an inner tube inlet 11 and an inner tube outlet 12, and the outer tube includes an outer tube inlet 13 and an outer tube outlet 14, the inner tube inlet 11 is used for high-temperature refrigerant gas to flow in; the inner tube outlet 12 is used for low-temperature refrigerant liquid to flow out; the outer tube inlet 13 is used for defrost liquid to flow in; the outer tube outlet 14 is used for defrost liquid or refrigerant to flow out; specifically, the inner tube The inlet 11 is connected with the outer tube inlet 13, which can be understood as the inner tube inlet 11 and the outer tube inlet 13 are two independent tube inlets, and there is a communication path between the two; the outer tube inlet 13 is provided with a first three-way valve 15, and the inner tube outlet 12 is connected with the outer tube outlet 14, which can be understood as the inner tube outlet 12 and the outer tube outlet 14 are two independent tube inlets, and there is a communication path between the two; the outer tube outlet 14 is provided with a second three-way valve 16; the first three-way valve 15 and the second three-way valve 16 are respectively electrically connected to the control system.

[0043] Under heating conditions, the control system controls the first three-way valve 15 to turn so that the first three-way valve 15 is blocked between the outer tube inlet 13 and the inner tube inlet 11; the control system controls the second three-way valve 16 to turn so that the second three-way valve 16 is blocked between the outer tube outlet 14 and the inner tube outlet 12, so that the refrigerant flows in through the inner tube inlet 11 and flows out from the inner tube outlet 12, and at the same time, the defrost liquid flows in through the outer tube inlet 13 and flows out from the outer tube outlet 14.

[0044] For example, a double-tube-fin heat exchanger 1, as a device for heat exchange, is centered around independent flow channels formed by two layers of tubing (inner and outer tubes). Each channel must have independent inlets and outlets to facilitate countercurrent or forward flow of the two fluids (e.g., the cold fluid flows through the inner tube, and the hot fluid flows through the annular gap between the outer and inner tubes). Regarding the inner tube: a fluid enters through an inlet at one end, flows through the inner tube, and exits through an outlet at the other end. Regarding the outer tube (annular gap): another fluid enters the annular gap at an inlet on the outer tube side, flows along the channels between the fins, and exits through the outlet. The primary function of the fins is to increase the heat transfer area and turbulent the fluid, but they do not alter the fluid's inlet and outlet paths. Whether the fins are oriented horizontally (radially) or longitudinally, the inlets and outlets of the two channels must be connected to the external piping to form a complete fluid circuit. In cooling and heating systems, the inner tube carries refrigerant (inlet in, outlet out), while the outer tube annular gap carries cooling water (a separate set of inlets and outlets).

[0045] This breaks the traditional mutually exclusive mode of heating and defrosting, which requires switching to cooling mode (such as reverse cycle defrosting), resulting in heating interruption or reduced energy efficiency. This solution utilizes a double-tube independent fluid path design, allowing the high-temperature refrigerant (inner tube) and defrost liquid (outer tube) to flow synchronously during heating conditions, enabling simultaneous heating and defrosting, significantly improving system continuity (for example, maintaining a stable indoor temperature without stopping the air conditioner for defrosting in winter).

[0046] Specifically, three-way valves are used to achieve "physical connectivity but operational isolation" between inner and outer tube inlet 11 and outlet 12 and outlet 14. During heating, the valves block the connection, ensuring independent circulation of fluids in the inner and outer tubes. When defrosting is required, or when defrosting conditions are met, the connection is opened to allow the high-temperature refrigerant and defrost liquid to interact synergistically. For example, the defrost liquid (e.g., hot water or ethylene glycol solution) in the outer tube can have its flow and temperature independently controlled, avoiding reliance on heat generated by the refrigeration system's reverse cycle. This approach is particularly suitable for scenarios where defrosting efficiency is insufficient in low-temperature environments (e.g., conventional reverse cycle defrosting is ineffective below -10°C. This solution improves defrosting reliability by heating the defrost liquid through an external heat source).

[0047] Furthermore, during heating, the high-temperature refrigerant flows only within the inner tube, with heat being transferred directly to the target area (such as the indoor air) via the fins. This prevents heat loss from the defrosting liquid in the outer tube to the heating side (in traditional integrated heat exchangers, the refrigerant must first heat the fins during defrosting before being used for heating, resulting in secondary heat exchange losses). The low-temperature refrigerant at inner tube outlet 12 flows directly back into the refrigeration system, reducing energy retention and improving cycle efficiency. Furthermore, the parallel double-tube design ensures independent channels for the refrigerant and defrosting liquid, avoiding reverse interference between the defrosting fluid and the refrigerant in traditional single-tube systems (such as increased pressure drop caused by turbulence), thereby reducing pump power loss and system load.

[0048] During defrost operation, the residual heat of the high-temperature refrigerant in the inner tube is transferred through the tube wall to the outer tube fins. Simultaneously, the defrost liquid on the outer tube removes frost through flushing and heat conduction, creating a combined defrost mode of "inner tube radiant heating + outer tube liquid flushing." This significantly improves defrost speed compared to single thermal melting or flushing methods. The flow direction of the outer tube fluid can be flexibly adjusted (e.g., forward or countercurrent) using a three-way valve to accommodate varying frost thickness and distribution, improving defrost uniformity.

[0049] For example, the control system can adjust the three-way valve opening and defrost liquid flow rate in real time based on relevant data (such as fin temperature and frost thickness), avoiding "over-defrosting" (e.g., running the defrost process when there is no frost, resulting in energy waste) or "under-defrosting" (e.g., failing to increase defrost power in a timely manner when frost is too thick). For example, during heating, the valve completely blocks the communication path, and the defrost liquid flow rate is zero. When frost is detected, the valve gradually opens the communication path, transferring some of the high-temperature refrigerant heat from the inner tube to the outer tube, while simultaneously increasing the defrost liquid flow rate, achieving "energy on demand."

[0050] Considering the safety and compatibility of the structural design, media isolation is achieved to prevent mixing risks. The inner tube (refrigerant) and outer tube (defrost liquid) are physically separated, eliminating the risks of corrosion, leakage, or chemical reactions caused by direct contact between the refrigerant and defrost liquid (e.g., damage to the equipment caused by brine seeping into the refrigerant piping in traditional defrost systems), thereby enhancing system safety. The three-way valve utilizes high-pressure, corrosion-resistant materials (e.g., stainless steel valve core), ensuring long-term stable operation with refrigerants (e.g., R32, CO2) and defrost liquids (e.g., antifreeze). The double-tube fin heat exchanger 1 also offers modular adaptability to existing systems. The double-tube fin heat exchanger 1 can directly replace traditional single-tube heat exchangers without significantly modifying the piping layout of existing cooling / heating equipment, reducing upgrade costs. For example, retrofitting an air conditioning unit requires only replacing the heat exchanger module, while the control system remains compatible through interfaces. The outer tube inlet 13 and outlet can be connected to independent defrost liquid storage tanks or circulation pumps, supporting both closed and open defrost systems for high flexibility.

[0051] Considering the energy-saving and operational advantages of intelligent control, it achieves multi-mode adaptive operation. The control system can preset a pure heating mode (valve blocked, no fluid in the outer pipe), a heating-and-defrosting mode (partially connected paths, low-intensity defrosting), and a forced defrost mode (fully connected, maximizing defrosting power). Using an algorithm, it automatically adapts to environmental conditions (for example, dynamically switching modes based on outdoor temperature and humidity), resulting in energy savings of 15%-20% compared to a fixed defrost cycle. It also facilitates fault diagnosis and maintenance by real-time monitoring of parameters such as the three-way valve status and fluid pressure / temperature. If a stuck valve (e.g., abnormal opening) or a blocked pipe (e.g., a sudden drop in defrost liquid flow) is detected, the system automatically issues an alarm and locates the fault location, reducing manual inspection costs and improving operational efficiency.

[0052] In summary, the solution of the defrost control system provided in the embodiment of the present application, through the core design of double-layer tube independent fluid path + intelligent three-way valve control, breaks through the technical bottleneck of the traditional defrost system that "heating and defrosting cannot be carried out in parallel", and achieves multiple technical effects of efficient heating, rapid defrosting, safety and reliability, and intelligent energy saving. It is especially suitable for heat pump units in cold areas, air-conditioning systems in high humidity environments, cold chain storage refrigeration equipment and other scenarios with high requirements for defrost efficiency and heating continuity, and has significant industrial application value and patent competitiveness. Specifically, the defrost function does not require defrosting by switching to refrigeration by turning the four-way valve 8. The unit can continue to heat and defrost. During normal heating, the three-way valve passes refrigerant up and down, and the water on the side is blocked. The refrigerant can flow through the heat exchanger and then flow away. When defrosting is required, for example, the control system controls the first three-way valve 15 to rotate 90° counterclockwise, and the control system controls the second three-way valve 16 to rotate 90° clockwise, which can block the refrigerant from flowing through the outer pipe and only allow it to flow through the inner pipe. Then, hot water can flow through the outer pipe to defrost the fins.

[0053] Considering the specific scheme of introducing defrost liquid into the outer pipe inlet 13, in the defrost control system provided in the embodiment of the present application, the outer pipe inlet 13 is connected to the second water pump 3 through the temperature sensing pipe 2; the inlet of the temperature sensing pipe 2 is connected between the second water pump 3 and the user-end heat exchanger 4; the temperature sensing pipe 2 is configured to transport defrost liquid within a preset temperature range to the outer pipe inlet 13.

[0054] In this way, the connection design between the temperature-sensing pipe 2 and the second water pump 3 enables precise control and efficient delivery of the defrost liquid temperature. The temperature-sensing pipe 2 takes liquid from between the second water pump 3 and the user-end heat exchanger 4, and can obtain the defrost liquid with a suitable temperature after heat exchange at the user end. When it is delivered to the outer tube inlet 13, it ensures that the liquid is within the preset temperature range, providing a stable and suitable heat source for the defrost process. It can avoid the problem of the defrost liquid temperature being too high or too low affecting the defrost effect. The temperature-adapted defrost liquid can effectively and quickly melt the frost layer on the surface of the outer tube of the double-layer tube fin heat exchanger 1, improve the defrost efficiency, and reduce the energy waste caused by improper temperature. In addition, the rational use of the liquid after the user-end heat exchanger 4 optimizes the energy cycle of the system and enhances the energy saving and reliability of the entire defrost control system.

[0055] Considering that the defrosting condition can continuously apply a solution of defrosting liquid with an appropriate temperature, in the solution of the defrost control system provided in the embodiment of the present application, the temperature sensing pipeline 2 is provided with a water path temperature sensing package 21 and an electric auxiliary heating device 22. The water path temperature sensing package 21 is arranged close to the second water pump 3. The water path temperature sensing package 21 and the electric auxiliary heating device 22 are respectively electrically connected to the control system. When the control system obtains that the temperature value measured by the water path temperature sensing package 21 is less than the preset temperature range, the control system controls the electric auxiliary heating device 22 to turn on to heat the defrosting liquid in the temperature sensing pipeline 2.

[0056] In this way, through the coordinated design of the water circuit temperature sensor 21 and the electric auxiliary heating device 22, dynamic and precise regulation of the defrost liquid temperature is achieved. The water circuit temperature sensor 21 is located near the second water pump 3 and monitors the defrost liquid temperature in real time. Once the temperature is detected to be lower than the preset range, the signal is fed back to the control system. The control system responds quickly and immediately controls the electric auxiliary heating device 22 to turn on, promptly heating the defrost liquid in the temperature sensing pipe 2, ensuring that the defrost liquid always remains in the appropriate temperature range. This can effectively solve the problem of poor defrosting effect caused by unstable defrost liquid temperature, ensuring that liquid of the appropriate temperature always acts on the heat exchanger under defrost conditions, and significantly improving defrost efficiency and stability. At the same time, the on-demand heating mechanism avoids ineffective energy consumption and improves the energy efficiency of the system. The linkage between the electric auxiliary heating device 22 and the control system also enhances the automation and intelligence of the defrost process, reduces the need for manual intervention, and improves the operational reliability and maintenance convenience of the entire system.

[0057] Considering the scheme of controlling the opening and closing of the temperature sensing pipe 2, in the scheme of the defrost control system provided in the embodiment of the present application, the temperature sensing pipe 2 is provided with a two-way valve 23, and the two-way valve 23 is connected between the electric auxiliary heating device 22 and the water channel temperature sensing package 21, and the two-way valve 23 is electrically connected to the control system.

[0058] In this way, in the defrost control system, a two-way valve 23 is added to the temperature sensing pipe 2 and electrically connected to the control system, thereby achieving precise control of the defrost liquid delivery. The two-way valve 23 is like an "intelligent switch" and is controlled by the instructions of the control system. It can flexibly open or close the temperature sensing pipe 2 according to the requirements of the defrost working conditions, thereby effectively controlling the on-off of the defrost liquid, avoiding unnecessary flow of the defrost liquid, and ensuring the orderly operation of the system. It can greatly improve the intelligence level and energy-saving effect of the defrost system. On the one hand, the two-way valve 23 is opened and closed on demand, and in conjunction with the water channel temperature sensing package 21 and the electric auxiliary heating device 22, the defrost liquid can enter the outer pipe at the right time and at the right temperature, thereby enhancing the defrost efficiency; on the other hand, it reduces the unnecessary flow of the defrost liquid, reduces the system's energy consumption and operating costs, and also facilitates system troubleshooting and maintenance, improving the reliability and stability of the overall operation.

[0059] Considering that the temperature sensing pipe 2 can be effectively defrosted, in the defrost control system provided in the embodiment of the present application, the temperature sensing pipe 2 is provided with a water flow switch 24, which is used to detect whether there is water flowing through the temperature sensing pipe 2, and the water flow switch 24 is electrically connected to the control system.

[0060] In this way, the water flow switch 24 installed in the temperature-sensing pipe 2 is connected to the control system, providing reliable water flow monitoring for the defrost process. The water flow switch 24 can detect in real time whether defrost liquid is flowing within the temperature-sensing pipe 2. If any abnormality in the defrost liquid flow occurs, such as a pipe blockage or a water pump failure causing a flow interruption, the water flow switch 24 can quickly detect it and feedback the signal to the control system, allowing the system to promptly detect the obstruction in the defrost process and buying time for subsequent troubleshooting. This significantly improves the stability and safety of the defrost control system. By accurately monitoring the water flow status, defrost failure caused by a lack of water flow or abnormal water flow is avoided, ensuring continuous and effective defrost operation. Furthermore, based on the information fed back by the water flow switch 24, the control system can promptly issue an alarm or take appropriate measures (such as shutting down the electric auxiliary heating device 22 to prevent dry heating), reducing the risk of equipment damage, lowering maintenance costs, and achieving intelligent and reliable operation of the defrost process.

[0061] When the water flow switch 24 detects that there is no liquid flowing, the control system can control the two-way valve 23 to close, and the defrosting mode of the temperature sensing pipe 2 is not adopted, but the traditional defrosting mode can be switched.

[0062] Considering that the new defrost control system provided in the embodiment of the present application can ensure the normal inflow and outflow of the defrost liquid, in the solution of the defrost control system provided in the embodiment of the present application, the outer pipe outlet 14 is connected to the first water pump 5, and the first water pump 5 is used to provide the defrost control system with pump pressure for defrosting under heating conditions.

[0063] In this way, the design of the outer tube outlet 14 being connected to the first water pump 5 provides stable power support for the defrost process of the defrost control system under heating conditions. As a key power source, the first water pump 5 can continuously output a stable pump pressure to ensure that the defrost liquid forms a stable circulation flow in the outer tube, and both the flow into and out of the outer tube are smoother and more efficient, avoiding the problem of slow flow of defrost liquid and low defrost efficiency due to insufficient power. It can effectively improve the reliability and practicality of the defrost system. The stable pump pressure ensures that the defrost liquid can reach all parts of the outer tube in a timely manner, give full play to the role of melting the frost layer, and improve the defrost effect; at the same time, it ensures that the defrost liquid can be discharged smoothly, maintains the internal pressure balance of the system, and prevents potential risks such as corrosion and blockage caused by residual defrost liquid, providing a solid guarantee for the stable operation of the entire defrost control system and extending the service life of the equipment.

[0064] An embodiment of the present application further provides an air conditioner, including the above-mentioned defrost control system, and also includes: a traditional heat pump unit, the traditional heat pump unit includes a compressor 6 and a throttle valve 7, the inner tube inlet 11 is connected to the compressor 6, for receiving the inflow of high-temperature refrigerant gas; the inner tube outlet 12 is connected to the throttle valve 7, for allowing the low-temperature refrigerant liquid to flow out.

[0065] In this way, the defrost control system is combined with a traditional heat pump unit to achieve efficient coordination of heating and defrosting functions. The inner tube inlet 11 is connected to the compressor 6, which can stably receive high-temperature refrigerant gas. After heat exchange in the inner tube, the low-temperature refrigerant liquid flows from the inner tube outlet 12 to the throttle valve 7, ensuring the smooth operation of the heating cycle. The defrost control system realizes the independent circulation of defrost liquid and refrigerant under heating conditions through the double-layer tube fin heat exchanger 1 and intelligent valve control, avoiding defrosting interfering with the heating effect. At the same time, when necessary, the high-temperature refrigerant waste heat can be used to coordinate defrosting with the defrost liquid, improving defrosting efficiency and ensuring that the air conditioner can operate stably and efficiently in different environments. It has both energy-saving and reliability, effectively improving the user experience.

[0066] The present application also provides a defrost control method, which uses the above-mentioned defrost control system or the above-mentioned air conditioner. The defrost control method includes:

[0067] Under heating conditions, make sure the unit meets the defrosting conditions;

[0068] The control system controls the reversal of the second three-way valve 16 so that the second three-way valve 16 is blocked between the outer tube outlet 14 and the inner tube outlet 12, and the high-temperature refrigerant gas flows into the inner tube inlet 11 to maintain the heating condition in the inner tube;

[0069] The control system controls the first three-way valve 15 to switch so that the first three-way valve 15 is blocked between the outer tube inlet 13 and the inner tube inlet 11 , and the defrost liquid flows in from the outer tube inlet 13 to perform the defrost process on the outer tube.

[0070] In this way, the defrost control method is based on the structural characteristics of the defrost control system and the air conditioner, and achieves efficient parallel heating and defrosting by precisely controlling the valve reversing. When the unit meets the defrost conditions, the control system quickly controls the reversing of the first and second three-way valves 16, accurately blocking the passage between the outer tube inlet 13 and the inner tube inlet 11, so that the high-temperature refrigerant gas can continue to stably perform a heating cycle in the inner tube, while the defrost liquid flows independently in the outer tube to carry out the defrost process. This control method avoids the problems of heating interruption or efficiency reduction during the traditional defrosting process, ensuring the comfort of the indoor temperature while quickly and effectively removing the frost layer on the outer tube fins, significantly improving the continuity, stability and energy efficiency of the equipment operation, and bringing users a better user experience.

[0071] Considering the control method for introducing defrost liquid into the outer tube inlet 13, and considering the solution of the control method for continuously applying the defrost liquid with an appropriate temperature during the defrost condition, in the solution of the defrost control method provided in the embodiment of the present application, the control system controls the second three-way valve 16 to reverse so that the second three-way valve 16 is blocked between the outer tube outlet 14 and the inner tube outlet 12, and the high-temperature refrigerant gas flows into the inner tube inlet 11, so that the inner tube maintains the heating condition. After the step, the defrost control method includes:

[0072] The control system controls the second water pump 3 to start;

[0073] When the temperature value measured by the water channel temperature sensing package 21 is less than the preset temperature range, the control system controls the electric auxiliary heating device 22 to turn on to heat the defrosting liquid in the temperature sensing pipe 2;

[0074] When the control system obtains that the temperature value measured by the water channel temperature sensing package 21 is greater than or equal to the preset temperature range, the control system controls the electric auxiliary heating device 22 to be turned off.

[0075] In this way, while ensuring that the inner tube maintains a heating condition, the temperature of the defrost liquid in the outer tube is further precisely controlled and intelligently managed. By orderly controlling the activation of the second water pump 3, the defrost liquid is ensured to flow into the temperature-sensing pipe 2 in a timely manner. The linkage mechanism between the waterway temperature sensor 21 and the electric auxiliary heating device 22 enables dynamic adjustment based on real-time temperature data: when the temperature falls below the preset range, the electric auxiliary heating device 22 is quickly activated to heat the defrost liquid, ensuring that it reaches a suitable defrosting temperature; when the temperature rises back to the preset range or higher, the electric auxiliary heating device 22 is promptly shut down to avoid energy waste. This method effectively solves the problem of unstable defrost liquid temperature affecting the defrost effect. It not only significantly improves defrost efficiency and stability, but also significantly enhances the system's energy-saving performance through on-demand heating, achieving intelligent and efficient operation of the defrost process.

[0076] Considering the control scheme of the control system after defrosting is completed, the defrost control method provided in the embodiment of the present application includes:

[0077] Determine whether the conditions for exiting defrost are met;

[0078] The control system controls the two-way valve 23 to close;

[0079] The control system controls the reversal of the first three-way valve 15;

[0080] The control system controls the reversing of the second three-way valve 16;

[0081] The control system controls the second water pump 3 to be turned off.

[0082] In this way, during the defrost completion phase, systematic control instructions are used to ensure that the defrost system safely and efficiently returns to normal operation. When it is determined that the conditions for exiting defrost are met, the control system performs a series of precise operations in sequence: first, the two-way valve 23 is closed to block the flow of defrost liquid in the temperature sensing pipe 2, avoiding unnecessary liquid transportation and waste; then, the first three-way valve 15 and the second three-way valve 16 are controlled to reverse, and the fluid path in the double-tube fin heat exchanger 1 is readjusted to restore the independent circulation of the refrigerant and defrost liquid under heating conditions; finally, the second water pump 3 is turned off to stop the supply of defrost liquid and reduce equipment energy consumption. This complete set of control processes not only effectively prevents problems such as resource waste and system disorder that may occur after defrosting, but also ensures that the various components of the equipment are reset in time and quickly switch to normal heating mode, improving the stability and energy efficiency of equipment operation, and reducing maintenance costs and potential failure risks.

[0083] Considering the scheme of the method for controlling the opening and closing of the temperature-sensing pipe 2, in the scheme of the defrost control method provided in the embodiment of the present application, under the heating condition, after the step of determining that the unit meets the defrost conditions, the control system controls the second three-way valve 16 to reverse so that the second three-way valve 16 is blocked between the outer pipe outlet 14 and the inner pipe outlet 12, and the high-temperature refrigerant gas flows into the inner pipe inlet 11, before the step of maintaining the inner pipe in the heating condition, the defrost control method includes:

[0084] The control system controls the two-way valve 23 to open, so that the second water pump 3, the temperature sensing pipe 2 and the double-tube fin heat exchanger 1 remain in a fully connected state.

[0085] In this way, in the defrost control process, by controlling the two-way valve 23 to open in advance, a complete flow path for the defrost liquid is established. After the unit meets the defrost conditions, before the heating mode is operated, the control system first opens the two-way valve 23 to ensure that the second water pump 3, the temperature sensing pipe 2, and the double-tube fin heat exchanger 1 are fully connected, allowing the defrost liquid to flow smoothly from the second water pump 3 through the temperature sensing pipe 2 into the outer tube of the double-tube fin heat exchanger 1. This operation avoids the problem of the defrost liquid being unable to be delivered in time due to the lack of pipeline conduction, ensuring that the defrost liquid can be quickly put into place and take effect when the defrost process begins, and seamlessly connects with the subsequent operation of the high-temperature refrigerant gas in the inner tube to maintain the heating mode. This improves the timeliness of the defrost system response and the overall operating efficiency, providing a guarantee for the efficient and stable implementation of the defrost process.

[0086] Considering that the temperature sensing pipe 2 can be effectively defrosted, in the defrost control method provided in the embodiment of the present application, after the control system controls the two-way valve 23 to open, the control system controls the second three-way valve 16 to reverse so that the second three-way valve 16 is blocked between the outer tube outlet 14 and the inner tube outlet 12, and the high-temperature refrigerant gas flows into the inner tube inlet 11 to maintain the inner tube in a heating state, the defrost control method includes:

[0087] The control system receives the detection result of the water flow switch 24, and executes the next step when the water flow switch 24 detects that water flows through the temperature sensing pipe 2.

[0088] In this way, by introducing the water flow switch 24 detection mechanism, the reliability and continuity of the defrost process are effectively guaranteed. After the control system opens the two-way valve 23 to connect the defrost liquid pipeline, it first receives the detection result of the water flow state in the temperature sensing pipeline 2 by the water flow switch 24. Only when the water flow switch 24 confirms that there is water flowing normally in the temperature sensing pipeline 2 will it continue to perform subsequent operations. This design avoids the risk of blindly starting the heating and defrosting parallel mode without water flow due to pipeline blockage, water pump failure, etc., ensuring that the defrost liquid can be effectively transported to the outer pipe for the defrost process. At the same time, it also prevents the inner pipe from continuing to heat without corresponding defrost cooperation, which may cause efficiency loss or equipment abnormality, thereby achieving safe and efficient coordination of the defrost process and heating conditions, and improving the stability and operating efficiency of the entire defrost control system.

[0089] Considering that the new defrost control system provided in the embodiment of the present application can ensure the control method scheme for the normal inflow and outflow of the defrost liquid, in the defrost control method scheme provided in the embodiment of the present application, a first time interval is left between the step of the control system controlling the reversal of the second three-way valve 16 and the step of the control system controlling the reversal of the second three-way valve 16.

[0090] In this way, setting a first time interval between the two reversing operations of the second three-way valve 16 effectively ensures the stable circulation of the defrost liquid and the reliability of the system operation. This time interval creates a buffer and stable condition for the inflow and outflow of the defrost liquid, avoiding fluid shock or pipeline pressure fluctuations caused by frequent and rapid reversal of the valve, and preventing the defrost liquid from being forced to change flow direction before it is fully exerted, ensuring that it can normally and fully complete the defrosting work within the outer tube of the double-layer tube-fin heat exchanger 1. At the same time, a reasonable time interval also helps the control system to more accurately coordinate the operation of various components, reduce the risk of equipment failure caused by excessively fast operation, improve the overall stability and operating efficiency of the defrost control system, and achieve efficient and orderly progress of the defrost process.

[0091] In summary, the embodiments of the present application provide a defrost control system, an air conditioner, and a defrost control method. When the fins of the unit are severely frosted during heating, causing the defrost temperature sensor to drop to a low level, reaching the defrost condition, the unit's original four-way valve 8 is inactive. The two-way valve 23 of the water path is first opened to allow water to flow. The subsequent water flow switch 24 detects whether water is flowing through the water path. If no water is detected, the unit switches back to the traditional defrost mode for defrosting. If the water flow switch 24 detects that water is flowing through the water path, the second three-way valve 16 is first switched to prevent water from flowing into the compressor 6. After 10 seconds (the first time interval is an illustrative example and may also be a preset time range, which is not limited here and can be determined based on actual operational requirements), the second three-way valve 16 is preferentially rotated to ensure that the path to the compressor 6 is blocked. Afterwards, the first three-way valve 15 is switched again, allowing water to flow through the outer tubes of the fins and out of the unit. After the first three-way valve 15 is switched, the first water pump 5 is also turned on to increase the water flow rate, which not only improves the defrosting heat exchange efficiency but also discharges the heated cold water out of the unit. This series of processes is called defrosting. During the defrosting process, hot water flows through the outer tubes of the double-tube fins, ensuring that the frost on the fins is effectively melted. The inner tubes of the fins are connected by a refrigerant bypass refrigerant to form a heating system circulation, allowing the unit to operate normally and heat during defrosting. At the same time, during the defrosting process, the temperature sensor in the water circuit also monitors the water temperature before the electric auxiliary heating is turned on in real time. When the water temperature is greater than 50°C, the electric auxiliary heating is turned off, and there is sufficient heat for defrosting. When the water temperature is less than 50°C, the electric auxiliary heating is turned on to increase the water temperature and ensure the efficiency of defrosting. When the defrosting of the unit is completed and the defrosting temperature sensor rises to the condition for exiting defrosting, the two-way valve 23 is closed first, and then the first three-way valve 15 is switched for 10 seconds and the second three-way valve 16 is switched again. After the first three-way valve 15 is switched, the first water pump 5 continues to run to drain the water in the outer tube of the fin to the outside of the unit. Finally, the first water pump 5 stops running after the second three-way valve 16 is switched, and the entire defrosting process is completed. For example, when defrosting is needed, the two-way valve 23 of the water circuit is opened first. If the water flow switch 24 detects that there is water passing through, the three-way valve is turned to allow water to flow into the fins. The first water pump 5 is also turned on to speed up the flow rate of water. The water circuit temperature sensor 21 and the electric auxiliary heating device 22 can be turned on to increase the water temperature when the water temperature is not high enough to affect the defrosting efficiency.

[0092] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0093] Although the terms first, second, third, etc. can be used in the text to describe multiple elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or section from another region, layer or section. Unless the context clearly indicates otherwise, terms such as "first", "second" and other numerical terms do not imply order or sequence when used in the text. Therefore, the first element, component, region, layer or section discussed below can be referred to as the second element, component, region, layer or section without departing from the teaching of the example embodiments.

[0094] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but is intended to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A defrost control system, characterized in that: The defrost control system comprises: A double-layer tube-fin heat exchanger, the double-layer tube-fin heat exchanger comprising an inner tube and an outer tube, the inner tube comprising an inner tube inlet and an inner tube outlet, the outer tube comprising an outer tube inlet and an outer tube outlet, the inner tube inlet being used to allow high-temperature refrigerant gas to flow in; the inner tube outlet being used to allow low-temperature refrigerant liquid to flow out; the outer tube inlet being used to allow defrost liquid to flow in; the outer tube outlet being used to allow defrost liquid or refrigerant to flow out; the inner tube inlet being connected to the outer tube inlet, the outer tube inlet being provided with a first three-way valve, the inner tube outlet being connected to the outer tube outlet, the outer tube outlet being provided with a second three-way valve; a control system, the control system being electrically connected to the first three-way valve and the second three-way valve respectively; In heating operation, when defrosting is required, the control system controls the first three-way valve to rotate so that the first three-way valve is blocked between the outer tube inlet and the inner tube inlet; the control system controls the second three-way valve to rotate so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, so that the refrigerant flows in through the inner tube inlet and flows out through the inner tube outlet, and at the same time, the defrost liquid flows in through the outer tube inlet and flows out through the outer tube outlet; Before the first three-way valve is turned, refrigerant flows through the annular gap between the outer tube and the inner tube.

2. The defrost control system according to claim 1, characterized in that: The outer tube inlet is connected to the second water pump through a temperature sensing pipeline; the inlet of the temperature sensing pipeline is connected between the second water pump and the user-end heat exchanger; the temperature sensing pipeline is configured to transport the defrost liquid within a preset temperature range to the outer tube inlet.

3. The defrost control system according to claim 2, characterized in that: The temperature sensing pipeline is provided with a water path temperature sensing package and an electric auxiliary heating device. The water path temperature sensing package is arranged close to the second water pump. The water path temperature sensing package and the electric auxiliary heating device are respectively electrically connected to the control system. When the control system obtains that the temperature value measured by the water path temperature sensing package is less than the preset temperature range, the control system controls the electric auxiliary heating device to turn on to heat the defrost liquid in the temperature sensing pipeline.

4. The defrost control system according to claim 3, characterized in that: The temperature sensing pipeline is provided with a two-way valve, the two-way valve is communicated between the electric auxiliary heating device and the water channel temperature sensing package, and the two-way valve is electrically connected to the control system.

5. The defrost control system according to claim 2, characterized in that: The temperature sensing pipeline is provided with a water flow switch, and the water flow switch is used to detect whether there is water flowing through the temperature sensing pipeline. The water flow switch is electrically connected to the control system.

6. The defrost control system according to claim 1, characterized in that: The outer pipe outlet is connected to a first water pump, and the first water pump is used to provide the defrost control system with pump pressure for defrosting under heating conditions.

7. An air conditioner, characterized in that: It includes a defrost control system as described in any one of claims 3-6, and also includes: a traditional heat pump unit, the traditional heat pump unit includes a compressor and a throttle valve, the inner tube inlet is connected to the compressor, and is used to receive the inflow of high-temperature refrigerant gas; the inner tube outlet is connected to the throttle valve, and is used to allow low-temperature refrigerant liquid to flow out.

8. A defrost control method, characterized in that: The defrost control system according to any one of claims 3 to 6 is applied, wherein the defrost control method comprises: Under heating conditions, make sure the unit meets the defrosting conditions; The control system controls the reversal of the second three-way valve, and the control system controls the reversal of the first three-way valve; the control system first controls the reversal of the second three-way valve so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, and the high-temperature refrigerant gas flows in from the inner tube inlet to maintain the heating condition in the inner tube; then controls the reversal of the first three-way valve so that the first three-way valve is blocked between the outer tube inlet and the inner tube inlet, and the defrost liquid flows in from the outer tube inlet to perform the defrost process in the outer tube.

9. The defrost control method according to claim 8, characterized in that: After the control system controls the second three-way valve to switch the second three-way valve so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, and high-temperature refrigerant gas flows into the inner tube inlet to maintain the heating condition in the inner tube, the defrost control method includes: The control system controls the second water pump to start; When the temperature value measured by the water channel temperature sensing package is lower than the preset temperature range, the control system controls the electric auxiliary heating device to turn on to heat the defrost liquid in the temperature sensing pipe; When the control system obtains that the temperature value measured by the water channel temperature sensing package is greater than or equal to the preset temperature range, the control system controls the electric auxiliary heating device to be turned off.

10. The defrost control method according to claim 9, characterized in that: The defrost control method comprises: Determining that the defrost exit condition is met, the control system controls the two-way valve to close, the control system controls the first three-way valve to reverse, the control system controls the second three-way valve to reverse, and the control system controls the second water pump to shut down.

11. The defrost control method according to claim 8, characterized in that: After determining that the unit meets the defrost condition under the heating condition, the control system controls the second three-way valve to switch so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, and high-temperature refrigerant gas flows into the inner tube inlet, so that the inner tube maintains the heating condition. Before the step of: The control system controls the two-way valve to open so as to keep the second water pump, the temperature sensing pipeline and the double-layer tube-fin heat exchanger in a fully connected state.

12. The defrost control method according to claim 11, characterized in that: After the control system controls the two-way valve to open, the control system controls the second three-way valve to switch so that the second three-way valve is blocked between the outer tube outlet and the inner tube outlet, and high-temperature refrigerant gas flows into the inner tube inlet to maintain the inner tube in a heating state, and before the step of: The control system receives the detection result of the water flow switch, and executes the next step when the water flow switch detects that water flows through the temperature sensing pipe.

13. The defrost control method according to claim 8, characterized in that: A first time interval is left between the completion of the step of the control system controlling the switching of the second three-way valve and the start of the step of the control system controlling the switching of the first three-way valve.

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