Defrosting control system, air conditioner and defrosting control method

Abstract

The invention relates to a defrosting control system, an air conditioner and a defrosting control method. The defrosting control system comprises a double-layer tube fin heat exchanger and a control system, the double-layer tube fin heat exchanger comprises an inner tube and an outer tube, the inner tube comprises an inner tube inlet and an inner tube outlet, the outer tube comprises an outer tube inlet and an outer tube outlet, the inner tube inlet is communicated with the outer tube inlet, the outer tube inlet is provided with a first three-way valve, and the inner tube outlet is communicated with the outer tube outlet. The outer pipe outlet is provided with a second three-way valve; the inner pipe inlet is used for allowing high-temperature refrigerant gas to flow in; the inner pipe outlet is used for flowing out of low-temperature refrigerant liquid; the outer pipe inlet is used for allowing defrosting liquid or refrigerant to flow in; the outer pipe outlet is used for enabling defrosting liquid to flow out; the control system is electrically connected with the first three-way valve and the second three-way valve. Under the heating working condition, the control system controls the first three-way valve to steer, so that the first three-way valve is blocked between the outer pipe inlet and the inner pipe inlet; the control system controls the second three-way valve to steer, so that the second three-way valve is blocked between the outer pipe inlet and the inner pipe inlet.

Description

Technical Field

[0001] This application relates to the field of air conditioner defrosting, and particularly to a defrosting control system, an air conditioner, and a defrosting control method. Background Art

[0002] In the field of air conditioner heating technology, with the continuous improvement of people's requirements for the comfort of the indoor environment, the heating performance of air conditioner units in low-temperature environments has received increasing attention. In low-temperature heating conditions, the refrigerant flowing through the defrosting control system of the outdoor unit of the air conditioner is in a low-temperature and low-pressure liquid state, which is extremely likely to cause frosting on the surface of the fins. Frosting will seriously affect the heating efficiency and performance of the air conditioner. Therefore, the defrosting technology has become the key to ensuring the stable operation of the air conditioner. Currently, traditional cooling and heating air conditioners generally use the method of switching the four-way valve for defrosting, that is, by changing the flow direction of the four-way valve, the system originally used for the heating cycle is switched to the cooling cycle, and the superheated gas is allowed to flow through the fins to achieve defrosting. However, in this process, the refrigerant in the defrosting control system at the user end of the unit becomes in a low-temperature and low-pressure state, making the end present a cooling state. This defrosting method will interrupt the heating function during defrosting, seriously affecting the normal use of users, reducing the comfort of users in cold environments, and unable to meet the users' demand for continuous and stable heating. Summary of the Invention

[0003] This application provides a defrosting control system to solve the technical problem in the above-mentioned prior art that the heating function is interrupted during defrosting, seriously affecting the normal use of users.

[0004] The present invention provides a defrosting control system, and the defrosting control system includes: a double-layer tube fin heat exchanger and a control system. Among them, 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, and the outer tube includes an outer tube inlet and an outer tube outlet. The inner tube inlet is communicated with the outer tube inlet, a first three-way valve is arranged at the outer tube inlet, the inner tube outlet is communicated with the outer tube outlet, and a second three-way valve is arranged at the outer tube outlet; the inner tube inlet is used for high-temperature refrigerant gas to flow in; the inner tube outlet is used for 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 defrosting liquid or refrigerant to flow out; the control system is electrically connected to the first three-way valve and the second three-way valve respectively; in the heating condition, the control system controls the first three-way valve to turn so that the first three-way valve blocks 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 blocks between the outer tube inlet and the inner tube inlet, so that the refrigerant flows in through the inner tube inlet and flows out through the inner tube outlet. At the same time, the defrosting liquid flows in through the outer tube inlet and flows out through the outer tube outlet.

[0005] Wherein, the outer pipe 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-side heat exchanger; the temperature sensing pipeline is configured to convey the defrosting liquid within a preset temperature range to the outer pipe inlet.

[0006] Wherein, the temperature sensing pipeline is provided with a waterway temperature sensing package and an electric auxiliary heating device. The waterway temperature sensing package is arranged close to the second water pump. The waterway temperature sensing package and the electric auxiliary heating device are respectively electrically connected to the control system. When the temperature value measured by the waterway temperature sensing package obtained by the control system is less than the preset temperature range, the control system controls the electric auxiliary heating device to turn on to heat the defrosting liquid in the temperature sensing pipeline.

[0007] 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 waterway temperature sensing package, and the two-way valve is electrically connected to the control system.

[0008] Wherein, the temperature sensing pipeline is provided with a water flow switch. 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.

[0009] Wherein, the outer pipe outlet is connected to the first water pump. The first water pump is used to provide the pump pressure for defrosting under the heating condition for the defrost control system.

[0010] The present invention further provides an air conditioner, including the above-mentioned defrost control system, and further including: a traditional heat pump unit, the traditional heat pump unit includes a compressor and a throttle valve. The inner pipe inlet is connected to the compressor and is used to receive the inflow of high-temperature refrigerant gas; the inner pipe outlet is connected to the throttle valve and is used to discharge low-temperature refrigerant liquid.

[0011] The present invention also provides a defrost control method, which is applied to the above-mentioned defrost control system. The defrost control method includes: Under the heating condition, it is determined that the unit meets the defrost condition; The control system controls the second three-way valve to change its direction, so that the second three-way valve blocks between the outer pipe inlet and the inner pipe inlet, and the high-temperature refrigerant gas flows in from the inner pipe inlet to maintain the heating condition in the inner pipe; The control system controls the first three-way valve to change its direction, so that the first three-way valve blocks between the outer pipe inlet and the inner pipe inlet, and the defrosting liquid flows in from the outer pipe inlet to perform the defrosting process on the outer pipe.

[0012] Among them, the control system controls the second three-way valve to change its direction, so that the second three-way valve blocks between the outer pipe inlet and the inner pipe inlet. After the step that high-temperature refrigerant gas flows in from the inner pipe inlet to maintain the heating working condition in the inner pipe, the defrosting control method includes: The control system controls the second water pump to start; When the control system obtains that the temperature value measured by the waterway temperature sensor is less than the preset temperature range, the control system controls the electric auxiliary heating device to start to heat the defrosting liquid in the temperature sensing pipeline; When the control system obtains that the temperature value measured by the waterway temperature sensor is greater than or equal to the preset temperature range, the control system controls the electric auxiliary heating device to turn off.

[0013] Among them, the defrosting control method includes: Determine that the defrosting exit condition is met; The control system controls the two-way valve to close; The control system controls the first three-way valve to change its direction; The control system controls the second three-way valve to change its direction; The control system controls the second water pump to close.

[0014] Among them, after the step of determining that the unit meets the defrosting condition under the heating working condition, before the step that the control system controls the second three-way valve to change its direction so that the second three-way valve blocks between the outer pipe inlet and the inner pipe inlet and high-temperature refrigerant gas flows in from the inner pipe inlet to maintain the heating working condition in the inner pipe, the defrosting control method includes: The control system controls the two-way valve to open, so that the second water pump, the temperature sensing pipeline and the double-layer tube fin heat exchanger are kept in a completely connected state.

[0015] Among them, after the step that the control system controls the two-way valve to open, before the step that the control system controls the second three-way valve to change its direction so that the second three-way valve blocks between the outer pipe inlet and the inner pipe inlet and high-temperature refrigerant gas flows in from the inner pipe inlet to maintain the heating working condition in the inner pipe, the defrosting control method includes: The control system receives the detection result of the water flow switch. When the water flow switch detects that there is water passing through the temperature sensing pipeline, the next step is executed.

[0016] Among them, there is a first time interval between the step that the control system controls the second three-way valve to change its direction and the step that the control system controls the second three-way valve to change its direction.

[0017] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art: The defrosting control system, air conditioner and defrosting control method provided by the embodiments of the present application. In the defrosting control system, a double-layer tube fin heat exchanger and a control system are applied. 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, and the outer tube includes an outer tube inlet and an outer tube outlet. The inner tube inlet is communicated with the outer tube inlet, and a first three-way valve is arranged at the outer tube inlet. The inner tube outlet is communicated with the outer tube outlet, and a second three-way valve is arranged at the outer tube outlet. It should be noted that the inner tube inlet is for high-temperature refrigerant gas to flow in, the inner tube outlet is for low-temperature refrigerant liquid to flow out, the outer tube inlet is for defrosting liquid to flow in, and the outer tube outlet is for defrosting liquid to flow out. Under the heating condition, the control system controls the first three-way valve to turn so that the first three-way valve blocks 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 blocks between the outer tube inlet and the inner tube inlet, so that the refrigerant can flow in through the inner tube inlet and flow out through the inner tube outlet. At the same time, the defrosting liquid flows in through the outer tube inlet and flows out through the outer tube outlet. In this way, when the unit is in the heating condition, it is ensured that the refrigerant flows in the inner tube and the defrosting liquid flows in the outer tube, so as to achieve the defrosting process while heating, that is, the air conditioner can heat while defrosting, which can greatly improve the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present invention and used together with the specification to explain the principles of the present invention.

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0020] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations 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 drawings in the figures do not constitute a proportional limitation.

[0021] Figure 1 Schematic structural diagram of the defrosting control system provided by the embodiments of the present application applied to an air conditioner; Figure 2 Schematic structural diagram of the first three-way valve and the second three-way valve installed on the double-layer tube fin heat exchanger provided by the embodiments of the present application.

[0022] Description of the reference numerals in the drawings: 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-side heat exchanger; 21. Waterway 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 implementation manners

[0023] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts shall fall within the scope of protection of the present application.

[0024] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, the components and settings of specific examples are described below. Of course, they are only 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. This repetition is for the purpose of simplification and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0025] For ease of description, spatially relative relationship terms may be used in the text to describe the relative positional relationship or movement of one element or feature shown in the figure relative to another element or feature. These relative relationship terms are, for example, "inner", "outer", "inner side", "outer side", "below", "beneath", "above", "upper", "front", "rear", etc. Such spatially relative relationship terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the figure. For example, if the device in the figure undergoes a position flip or attitude change or movement state change, then these directional indications will change accordingly. For example, an element described as "below" or "beneath" other elements or features will subsequently be oriented as "above" or "upper" other elements or features. Therefore, the exemplary term "below" can include both the upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions) and the spatially relative relationship descriptions used in the text will be interpreted accordingly.

[0026] At present, traditional heating and cooling air conditioners generally use a four-way valve switching method for defrosting, that is, by changing the flow direction of the four-way valve, the system originally used for the heating cycle is switched to the cooling cycle, and the superheated gas flows through the fins to achieve defrosting. However, in this process, the refrigerant in the defrosting control system at the user end of the unit becomes in a low-temperature and low-pressure state, resulting in a cooling state at the end. This defrosting method will interrupt the heating function during defrosting, seriously affecting the normal use of users, reducing the comfort of users in cold environments, and unable to meet the users' demand for continuous and stable heating.

[0027] Specifically, in the existing traditional heat pump units in application, the left flow path of the user-side heat exchanger is for the refrigerant to flow through, and the right side is for water to flow through. When heating normally, the high-temperature gas refrigerant coming out of the compressor passes through the four-way valve (the four-way valve is connected in pairs), goes down to the user-side heat exchanger to supply heat to the user, and then passes through the throttle valve to the fins. Then it returns to the compressor following the black arrow through the four-way valve. For refrigeration or defrosting, the four-way valve is rotated, and the high-temperature gas refrigerant coming out of the compressor goes up through the four-way valve, first passes through the fins, goes around and returns to the four-way valve and then back to the compressor.

[0028] When defrosting, the high-temperature gas refrigerant will become low-temperature liquid refrigerant after passing through the fins and the electronic expansion valve and reach the user end. Therefore, defrosting is the opposite of when heating, which will affect normal heating.

[0029] In order to alleviate the above technical problems, the embodiment of the present application provides a new defrosting control system, which is applied to an air conditioner and can realize the defrosting process while in the heating working condition.

[0030] Reference Figure 1 - Figure 2 , the embodiment of the present application provides a new defrosting control system, including a double-tube fin heat exchanger 1 and a control system. Among them, the double-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 defrosting liquid to flow in; the outer tube outlet 14 is used for defrosting liquid or refrigerant to flow out; specifically, the inner tube inlet 11 is communicated with the outer tube inlet 13. It can be understood that the inner tube inlet 11 and the outer tube inlet 13 are two independent tube inlets, and there is a communication path between them; a first three-way valve 15 is arranged at the outer tube inlet 13, and the inner tube outlet 12 is communicated with the outer tube outlet 14. It can be understood that the inner tube outlet 12 and the outer tube outlet 14 are two independent tube inlets, and there is a communication path between them; a second three-way valve 16 is arranged at the outer tube outlet 14; the first three-way valve 15 and the second three-way valve 16 are respectively electrically connected to the control system.

[0031] 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 inlet 13 and the inner tube inlet 11, 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.

[0032] Exemplarily, the double-layer tube-fin heat exchanger 1 is a device for achieving heat exchange. Its core is an independent flow channel formed by two layers of pipes (inner tube and outer tube). Each layer of the flow channel must have an independent inlet and outlet to achieve reverse or forward flow of the two fluids (such as the cold fluid goes through the inner tube, and the hot fluid goes through the annular gap between the outer tube and the inner tube). Regarding the inner tube: the fluid flows in from the inlet at one end, flows through the inner tube, and flows out from the outlet at the other end. Regarding the outer tube (annular gap): another fluid enters the annular gap space from the inlet on the outer tube side, flows along the channel between the fins, and is discharged from the outlet. The main function of the fin is to enhance the heat transfer area and disturb the fluid, but it will not change the inlet and outlet path of the fluid. Regardless of whether the fin is horizontal (radial) or longitudinal, it is necessary to ensure that the inlet and outlet of the two-layer flow channel are connected to the external pipeline to form a complete fluid cycle. In the refrigeration system and heating system, the refrigerant is carried in the inner tube (inlet in, outlet out), and the cooling water is carried in the annular gap of the outer tube (another set of inlet in, outlet out).

[0033] In this way, the mutually exclusive mode of traditional heating and defrosting can be broken. Traditional defrosting requires switching to cooling mode (such as reverse cycle defrosting), resulting in heating interruption or reduced energy efficiency. This solution uses a double-layer tube independent fluid path design to allow high-temperature refrigerant (inner tube) and defrosting liquid (outer tube) to flow synchronously under heating conditions, achieving heating and defrosting in parallel, significantly improving system continuity (for example, the air conditioner does not need to be shut down for defrosting in winter to maintain indoor temperature stability).

[0034] Specifically, the inner tube inlet 11 and the outer tube inlet 13, as well as the inner tube outlet 12 and the outer tube outlet 14 are "physically connected but isolated from the working conditions" through a three-way valve - during heating, the valve blocks the connecting path to ensure that the inner and outer tube fluids circulate independently; when defrosting is required, or when the defrosting conditions are met, the path can be opened to allow the high-temperature refrigerant and the defrosting liquid to work together. Exemplarily, the defrosting liquid (such as hot water, ethylene glycol solution) of the outer tube can independently control the flow and temperature to avoid relying on the heat generated by the reverse cycle of the refrigeration system, which is particularly suitable for scenarios where the defrosting efficiency is insufficient in low-temperature environments (such as the traditional reverse cycle defrosting effect is poor below -10°C, and this solution can heat the defrosting liquid through an external heat source to improve the defrosting reliability).

[0035] Furthermore, during heating, the high-temperature refrigerant only flows in the inner tube, and the heat is directly transferred to the target area (such as indoor air) through the fins, avoiding the heat loss on the heating side caused by the defrosting liquid in the outer tube. (In traditional integrated heat exchangers, during defrosting, the refrigerant needs to first heat the fins and then be used for heating, resulting in secondary heat exchange losses.) The low-temperature refrigerant at the outlet 12 of the inner tube directly returns to the refrigeration system, reducing energy retention and improving the cycle efficiency. In addition, the double-tube parallel design enables the refrigerant and the defrosting liquid to have independent channels respectively, avoiding the reverse interference between the defrosting fluid and the refrigerant in the traditional single-tube system (such as the increase in pressure drop caused by turbulence), and reducing the pump power loss and system load.

[0036] When entering the defrosting mode, the waste heat of the high-temperature refrigerant in the inner tube can be conducted to the fins of the outer tube through the tube wall. At the same time, the defrosting liquid in the outer tube removes the frost through flushing and heat conduction, forming a composite defrosting mode of "inner tube radiation heating + outer tube liquid flushing". Compared with the single heat melting or flushing method, the defrosting speed is increased significantly. The flow direction of the fluid in the outer tube can be flexibly adjusted through a three-way valve (such as flowing forward or backward) to adapt to different frost thicknesses and distributions, improving the defrosting uniformity.

[0037] Exemplarily, the control system can adjust the opening degree of the three-way valve and the flow rate of the defrosting liquid in real time according to corresponding data (such as fin temperature, frost thickness, etc.), avoiding "over-defrosting" (such as wasting energy due to still running the defrosting process when there is no frost) or "insufficient defrosting" (such as not enhancing the defrosting power in time when the frost is too thick). For example: during heating, the valve completely blocks the connection path and the flow rate of the defrosting liquid is 0; when frost is detected, the valve is gradually opened to connect the path, and the heat of part of the high-temperature refrigerant in the inner tube is introduced into the outer tube. At the same time, the flow rate of the defrosting liquid is increased to achieve "energy supply on demand".

[0038] Considering the safety and compatibility of the structural design, the effect of medium isolation to prevent mixing risks can be achieved. The inner tube (refrigerant) and the outer tube (defrosting liquid) are physically independent, avoiding the risks of corrosion, leakage or chemical reaction caused by the direct contact between the refrigerant and the defrosting liquid (such as the equipment damage caused by the infiltration of the traditional brine defrosting system into the refrigerant pipeline). The safety of the system is improved. The three-way valve is made of high-pressure and corrosion-resistant materials (such as stainless steel valve core) to adapt to the long-term stable operation of the refrigerant (such as R32, CO2) and the defrosting liquid (such as antifreeze). The effect of modular adaptation to the existing system can also be achieved. The double-tube fin heat exchanger 1 can directly replace the traditional single-tube heat exchanger without significantly changing the pipeline layout of the existing refrigeration / heating equipment, reducing the technical transformation cost (such as only replacing the heat exchanger module during the transformation of the air-conditioning unit, and the control system can be compatible through the interface). The inlet 13 / outlet of the outer tube can be externally connected to an independent defrosting liquid storage tank or a circulation pump, supporting a closed or open defrosting system, with high flexibility.

[0039] Considering the energy saving and operation and maintenance advantages of intelligent control, the effect of multi-mode adaptive operation can be achieved. The control system can preset pure heating mode (valve blocked, no fluid in the outer pipe), heating and defrosting mode (partially connected path, low-intensity defrosting), and forced defrosting mode (fully connected, maximized defrosting power). The algorithm automatically matches the environmental conditions (such as dynamically switching modes according to outdoor temperature and humidity), which saves 15%-20% energy compared to fixed defrosting cycles. It can also achieve the effect of fault diagnosis and maintenance convenience, and monitor the switch status of the three-way valve, fluid pressure / temperature and other parameters in real time. When the valve is detected to be stuck (such as abnormal opening) or the pipeline is blocked (such as a sudden drop in the defrosting liquid flow), the system automatically alarms and locks the fault location, reducing the cost of manual inspections and improving operation and maintenance efficiency.

[0040] 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 defrosting efficiency and heating continuity, and has significant industrial application value and patent competitiveness. Specifically, the defrost function does not require defrosting by turning the four-way valve 8 to switch refrigeration to defrost, and the unit can continue to heat and defrost. During normal heating, the three-way valve is connected to the top and bottom of the refrigerant, 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.

[0041] Considering the specific scheme of introducing defrost liquid into the outer tube inlet 13, in the defrost control system provided in the embodiment of the present application, the outer tube inlet 13 is connected to the second water pump 3 through the temperature sensing pipeline 2; the inlet of the temperature sensing pipeline 2 is connected between the second water pump 3 and the user-end heat exchanger 4; the temperature sensing pipeline 2 is configured to transport defrost liquid within a preset temperature range to the outer tube inlet 13.

[0042] In this way, the temperature of the defrost liquid can be precisely controlled and efficiently transported through the connection design between the temperature sensing pipeline 2 and the second water pump 3. The temperature sensing pipeline 2 takes liquid from between the second water pump 3 and the user-end heat exchanger 4, and can obtain the defrost liquid with suitable temperature after heat exchange at the user end. When it is transported to the outer tube inlet 13, it is ensured that the liquid is in the preset temperature range, providing a stable and suitable heat source for the defrost process. It can avoid the problem that the defrost liquid temperature is too high or too low to affect 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.

[0043] 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, and the water path temperature sensing package 21 is arranged close to the second water pump 3, and 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, so as to heat the defrosting liquid in the temperature sensing pipeline 2.

[0044] In this way, the dynamic and precise adjustment of the defrost liquid temperature is achieved through the coordinated design of the water circuit temperature sensing package 21 and the electric auxiliary heating device 22. The water circuit temperature sensing package 21 is close to the second water pump 3 to monitor 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, and heats the defrost liquid in the temperature sensing pipeline 2 in time to ensure that the defrost liquid is always kept in a suitable temperature range. It can effectively solve the problem of poor defrosting effect caused by unstable defrost liquid temperature, ensure that there is always liquid of suitable temperature acting on the heat exchanger under defrosting conditions, and greatly improve the defrosting efficiency and stability; at the same time, the on-demand heating mechanism avoids the ineffective consumption of energy and improves the energy saving 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.

[0045] Considering the scheme of controlling the opening and closing of the temperature sensing pipeline 2, in the scheme of the defrost control system provided in the embodiment of the present application, the temperature sensing pipeline 2 is provided with a two-way valve 23, the two-way valve 23 is connected between the electric auxiliary heating device 22 and the water circuit temperature sensing bag 21, and the two-way valve 23 is electrically connected to the control system.

[0046] In this way, in the defrost control system, a two-way valve 23 is added to the temperature sensing pipeline 2 and electrically connected to the control system, achieving precise control of the defrost liquid delivery. The two-way valve 23 is like an "intelligent switch", controlled by the instructions of the control system. It can flexibly open or close the temperature sensing pipeline 2 according to the defrost working condition requirements, 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 intelligent level and energy-saving effect of the defrost system. On the one hand, the two-way valve 23 opens and closes as needed, cooperating with the waterway temperature sensing package 21 and the electric auxiliary heating device 22, enabling the defrost liquid to enter the outer pipe at the right time and at the appropriate temperature, enhancing the defrost efficiency; on the other hand, reducing the unnecessary flow of the defrost liquid reduces the system energy consumption and operation cost, and at the same time facilitates the system for fault troubleshooting and maintenance, improving the overall operation reliability and stability.

[0047] Considering the solution that the temperature sensing pipeline 2 can effectively defrost, in the defrost control system solution provided by the embodiment of the present application, a water flow switch 24 is provided in the temperature sensing pipeline 2. The water flow switch 24 is used to detect whether there is water flow through the temperature sensing pipeline 2, and the water flow switch 24 is electrically connected to the control system.

[0048] In this way, the water flow switch 24 provided in the temperature sensing pipeline 2 is connected to the control system, providing a reliable water flow monitoring guarantee for the defrosting process. The water flow switch 24 can detect in real time whether there is defrost liquid flowing in the temperature sensing pipeline 2. Once the flow of the defrost liquid is abnormal, such as pipeline blockage, water cut caused by pump failure, etc., the water flow switch 24 can quickly sense and feedback the signal to the control system, enabling the system to promptly detect that the defrost process is blocked and buying time for subsequent fault handling. It can significantly improve the stability and safety of the defrost control system. Through precise monitoring of the water flow state, it avoids defrost failure caused by no water flow or abnormal water flow, ensuring that the defrost operation can be carried out continuously and effectively; at the same time, based on the information feedback by the water flow switch 24, the control system can promptly issue an alarm or take corresponding measures (such as turning off the electric auxiliary heating device 22 to avoid dry burning), reducing the risk of equipment damage, lowering the maintenance cost, and realizing the intelligent and reliable operation of the defrost process.

[0049] When the water flow switch 24 detects that there is no liquid flowing through, the control system can control the two-way valve 23 to close, not adopting the defrosting method of the temperature sensing pipeline 2, but can switch to the traditional defrost mode.

[0050] Considering that the new defrost control system provided by the embodiment of the present application can ensure the normal inflow and outflow of the defrost liquid, in the defrost control system solution provided by 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 pump pressure for defrosting under the heating working condition of the defrost control system.

[0051] In this way, the design of the outer tube outlet 14 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. The reliability and practicality of the defrost system can be effectively improved. The stable pump pressure ensures that the defrost liquid can reach all parts of the outer tube in time, 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, which provides a solid guarantee for the stable operation of the entire defrost control system and extends the service life of the equipment.

[0052] The 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.

[0053] In this way, the defrost control system is combined with the 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 to ensure the smooth operation of the heating cycle; and 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 the 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 to improve the defrosting efficiency, ensuring that the air conditioner can work stably and efficiently in different environments, combining energy saving and reliability, and effectively improving the user experience.

[0054] The embodiment of the present application further provides a defrost control method, which uses the above-mentioned defrost control system or the above-mentioned air conditioner, and the defrost control method includes: Under heating conditions, make sure the unit meets the defrosting conditions; The control system controls the second three-way valve 16 to switch, so that the second three-way valve 16 is blocked between the outer tube inlet 13 and the inner tube inlet 11, and the high-temperature refrigerant gas flows in from the inner tube inlet 11 to maintain the heating condition in the inner tube; The control system controls the first three-way valve 15 to switch direction so that the first three-way valve 15 is blocked between the outer tube inlet 13 and the inner tube inlet 11, and the defrosting liquid flows in from the outer tube inlet 13 to perform the defrosting process in the outer tube.

[0055] In this way, based on the structural characteristics of the defrost control system and the air conditioner, the defrost control method realizes the efficient parallel operation of heating and defrosting by precisely controlling the valve commutation. When the unit meets the defrost condition, the control system quickly controls the first and second three-way valves 16 to commutate, precisely blocking the passage between the outer pipe inlet 13 and the inner pipe inlet 11, so that the high-temperature refrigerant gas can continuously and stably carry out the heating cycle in the inner pipe, while the defrosting liquid independently flows in the outer pipe to carry out the defrosting process. This control method avoids the problems of heating interruption or efficiency decline during the traditional defrosting process, not only ensures the comfort of the indoor temperature, but also can quickly and effectively remove the frost layer on the fins of the outer pipe, significantly improving the continuity, stability and energy utilization efficiency of the equipment operation, and bringing a better user experience to users.

[0056] Considering the control method of introducing the defrosting liquid into the outer pipe inlet 13, and the solution of the defrost control method provided by the embodiment of the present application that can continuously apply the defrosting liquid control method at an appropriate temperature under the defrosting condition, after the control system controls the second three-way valve 16 to commutate so that the second three-way valve 16 blocks between the outer pipe inlet 13 and the inner pipe inlet 11, and the high-temperature refrigerant gas flows in from the inner pipe inlet 11 to maintain the heating condition in the inner pipe, the defrost control method includes: The control system controls the second water pump 3 to start; When the control system obtains that the temperature value measured by the waterway temperature sensor 21 is less than the preset temperature range, the control system controls the electric auxiliary heating device 22 to start to heat the defrosting liquid in the temperature sensing pipeline 2; When the control system obtains that the temperature value measured by the waterway temperature sensor 21 is greater than or equal to the preset temperature range, the control system controls the electric auxiliary heating device 22 to turn off.

[0057] In this way, on the basis of ensuring that the inner pipe maintains the heating condition, the precise regulation and intelligent management of the temperature of the defrosting liquid in the outer pipe are further realized. By orderly controlling the start of the second water pump 3, it is ensured that the defrosting liquid flows into the temperature sensing pipeline 2 in time, and the linkage mechanism of the waterway temperature sensor 21 and the electric auxiliary heating device 22 can perform dynamic adjustment according to the real-time temperature data: when the temperature is lower than the preset range, the electric auxiliary heating device 22 is quickly started to heat the defrosting liquid to ensure that it reaches the appropriate defrosting temperature; when the temperature rises to the preset range or higher, the electric auxiliary heating device 22 is timely turned off to avoid energy waste. This method effectively solves the problem that the unstable temperature of the defrosting liquid affects the defrosting effect, not only significantly improves the defrosting efficiency and stability, but also greatly enhances the energy-saving performance of the system by supplying heat on demand, realizing the intelligent and efficient operation of the defrosting process.

[0058] Considering the control scheme of the control system after defrosting is completed, in the defrost control method provided by the embodiment of the present application, the defrost control method includes: Determine that the condition for exiting defrosting is met; The control system controls the two-way valve 23 to close; The control system controls the first three-way valve 15 to change its direction; The control system controls the second three-way valve 16 to change its direction; The control system controls the second water pump 3 to close.

[0059] In this way, during the defrost completion stage, through systematic control instructions, it is ensured that the defrost system safely and efficiently returns to normal operation. When it is determined that the defrost exit conditions are met, the control system sequentially executes a series of precise operations: first, close the two-way valve 23 to block the flow of defrost liquid in the temperature sensing pipeline 2 and avoid unnecessary transportation and waste of the liquid; then control the first three-way valve 15 and the second three-way valve 16 to change their directions, readjust the fluid path in the double-layer tube fin heat exchanger 1, and restore the independent circulation of the refrigerant and the defrost liquid under the heating condition; finally, close the second water pump 3 to stop the supply of defrost liquid and reduce the energy consumption of the equipment. This complete control process not only effectively prevents problems such as resource waste and system disorder that may occur after defrosting, but also ensures that each component of the equipment is reset in a timely manner, quickly switches to the normal heating mode, improves the stability and energy efficiency of the equipment operation, and reduces the maintenance cost and potential failure risk.

[0060] Considering the scheme of the on-off control method of the temperature sensing pipeline 2, in the scheme of the defrost control method provided by the embodiment of the present application, under the heating condition, after the step of determining that the unit meets the defrost condition and before the step of controlling the second three-way valve 16 to change its direction so that the second three-way valve 16 blocks between the outer pipe inlet 13 and the inner pipe inlet 11 and the high-temperature refrigerant gas flows in from the inner pipe inlet 11 to maintain the heating condition in the inner pipe, the defrost control method includes: The control system controls the two-way valve 23 to open so that the second water pump 3, the temperature sensing pipeline 2 and the double-layer tube fin heat exchanger 1 are kept in a completely connected state.

[0061] In this way, in the defrost control process, by controlling the two-way valve 23 to open in advance, a complete flow path of the defrost liquid is constructed. After the unit meets the defrost condition and before the heating condition operation, the control system first opens the two-way valve 23 to ensure that the second water pump 3, the temperature sensing pipeline 2 and the double-layer tube fin heat exchanger 1 are completely connected, so that the defrost liquid can flow smoothly from the second water pump 3 through the temperature sensing pipeline 2 into the outer pipe of the double-layer tube fin heat exchanger 1. This operation avoids the problem that the defrost liquid cannot be transported in time due to the unconnected pipeline, ensures that the defrost liquid can be quickly in place and play a role at the beginning of the defrost process, seamlessly connects with the subsequent operation of maintaining the heating condition of the high-temperature refrigerant gas in the inner pipe, improves the timeliness of the defrost system response and the overall operation efficiency, and provides guarantee for the efficient and stable development of the defrost process.

[0062] Considering the solution of the temperature-sensitive pipeline 2 that can implement an effective defrost control method, in the solution of the defrost control method provided by the embodiments of the present application, after the step of the control system controlling the two-way valve 23 to open, the control system controls the second three-way valve 16 to change its direction, so that the second three-way valve 16 blocks between the outer pipe inlet 13 and the inner pipe inlet 11. Before the step of high-temperature refrigerant gas flowing into the inner pipe inlet 11 to maintain the heating condition in the inner pipe, the defrost control method includes: The control system receives the detection result of the water flow switch 24. When the water flow switch 24 detects that there is water passing through the temperature-sensitive pipeline 2, the next step is executed.

[0063] In this way, by introducing the detection mechanism of the water flow switch 24, the reliability and coherence 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 switch 24 on the water flow state in the temperature-sensitive pipeline 2. Only when the water flow switch 24 confirms that there is normal water passing through the temperature-sensitive pipeline 2, will it continue to execute the subsequent operations. This design avoids the risk of blindly starting the parallel mode of heating and defrosting due to pipeline blockage, water pump failure, etc. without water flow, ensures that the defrost liquid can be effectively transported to the outer pipe for the defrosting process, and also prevents the efficiency loss or equipment abnormality that may be caused by continuous heating of the inner pipe without corresponding defrost cooperation. Thus, the safe and efficient coordination of the defrost process and the heating condition is realized, and the stability and operation efficiency of the entire defrost control system are improved.

[0064] Considering the solution of the control method for ensuring the normal inflow and outflow of the defrost liquid provided by the embodiments of the present application, in the solution of the defrost control method provided by the embodiments of the present application, there is a first time interval between the step of the control system controlling the second three-way valve 16 to change its direction and the step of the control system controlling the second three-way valve 16 to change its direction.

[0065] In this way, setting a first time interval between two commutation operations of the second three-way valve 16 effectively guarantees the stable flow 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, avoids fluid impact or pipeline pressure fluctuation caused by frequent and rapid valve commutation, prevents the defrost liquid from being forced to change its flow direction before it fully functions, and ensures that it can complete the defrost work normally and fully in the outer pipe of the double-layer finned heat exchanger 1. At the same time, a reasonable time interval also helps the control system to more precisely coordinate the operation of each component, reduces the risk of equipment failure caused by too fast operation, improves the overall stability and operation efficiency of the defrost control system, and realizes the efficient and orderly progress of the defrost process.

[0066] In summary, the embodiments of the present application provide a defrosting control system, an air conditioner, and a defrosting control method. When the unit is in the heating mode and severe frosting on the fins causes the defrosting temperature sensor to drop to meet the defrosting condition, the original four-way valve 8 of the unit does not operate. First, the two-way valve 23 in the water circuit is opened to allow water to pass through. Then, the subsequent water flow switch 24 detects whether water passes through the water circuit. If it is detected that no water passes through the water circuit, the unit switches back to the traditional defrosting mode for defrosting. If the water flow switch 24 detects that water passes through the water circuit, the second three-way valve 16 first changes its direction to prevent water from flowing into the compressor 6. After 10 seconds (an exemplary example of the first time interval, which can also be a preset time range and is not limited here and can be determined according to actual operation requirements), the second three-way valve 16 is preferentially rotated to ensure that the path leading to the compressor 6 is blocked. After that, the first three-way valve 15 changes its direction, and at this time, the water can flow through the outer pipe of the fins and then out of the unit. After the first three-way valve 15 changes its direction, the first water pump 5 is also turned on to increase the water flow rate, which can not only improve the defrosting heat exchange efficiency but also discharge the cooled water after heat exchange out of the unit. This series of processes is the defrosting process. During the defrosting process, hot water flows in the outer pipe of the double-layer tube fin, which can effectively melt the frost on the fins. The refrigerant passes through the inner pipe of the fin through the bypass refrigerant to form a heating system cycle, and the unit can operate normally in the heating mode during defrosting. At the same time, during the defrosting process of the fins, the temperature sensor in the water circuit also continuously detects the water temperature before the electric auxiliary heating in the water circuit. When the water temperature is greater than 50°C, the electric auxiliary heating is not turned on, 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 to ensure the defrosting efficiency. 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 first closed, then the first three-way valve 15 changes its direction, and 10 seconds later, the second three-way valve 16 changes its direction. After the first three-way valve 15 changes its direction, the first water pump 5 still continues to operate to drain the water in the outer pipe of the fins out of the unit. Finally, the first water pump 5 stops operating after the second three-way valve 16 changes its direction, and the entire defrosting process ends. Exemplarily, when defrosting is required, the two-way valve 23 in the water circuit is first opened. If the water flow switch 24 detects that water passes through, the three-way valve is rotated to allow water to enter the fins, and the first water pump 5 is also turned on to increase the water flow rate. The water temperature sensor 21 in the water circuit and the electric auxiliary heating device 22 can turn on the electric auxiliary heating to increase the water temperature when it is detected that the water temperature is not high enough to affect the defrosting efficiency.

[0067] It should be understood that the terms used herein are for the purpose of describing particular example embodiments only and are not intended to be limiting. Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" as used herein may also include the plural forms. The terms "comprising", "including", "containing", and "having" are inclusive and thus specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order described or illustrated, unless an execution order is explicitly stated. It should also be understood that additional or alternative steps may be used.

[0068] Although the terms first, second, third, etc. may be used herein 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 may be used only to distinguish one element, component, region, layer, or section from another. Unless the context clearly indicates otherwise, terms such as "first", "second", and other numerical terms when used herein do not imply an order or sequence. Thus, the first element, component, region, layer, or section discussed below may be referred to as the second element, component, region, layer, or section without departing from the teachings of the example embodiments.

[0069] The foregoing are only specific embodiments of the present invention, enabling those skilled in the art to understand or 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 will not be limited to the embodiments shown herein, but rather is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A defrosting control system, characterized in that, The defrosting control system includes: A double-layer tube fin heat exchanger, which includes an inner tube and an outer tube. The inner tube includes an inner tube inlet and an inner tube outlet, and the outer tube includes an outer tube inlet and an outer tube outlet. The inner tube inlet is used to allow high-temperature refrigerant gas to flow in; the inner tube outlet is used for 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 defrosting liquid or refrigerant to flow out; the inner tube inlet is communicated with the outer tube inlet, a first three-way valve is arranged at the outer tube inlet, the inner tube outlet is communicated with the outer tube outlet, and a second three-way valve is arranged at the outer tube outlet; A control system, which is electrically connected to the first three-way valve and the second three-way valve respectively; Under the heating condition, the control system controls the first three-way valve to turn so that the first three-way valve blocks 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 blocks between the outer tube inlet and the inner tube inlet, so that the refrigerant flows in through the inner tube inlet and flows out through the inner tube outlet. At the same time, the defrosting liquid flows in through the outer tube inlet and flows out through the outer tube outlet.

2. The defrosting control system according to claim 1, wherein The outer tube inlet is communicated with a second water pump through a temperature sensing pipeline; the inlet of the temperature sensing pipeline is communicated between the second water pump and the user-side heat exchanger; the temperature sensing pipeline is configured to convey the defrosting liquid within a preset temperature range to the outer tube inlet.

3. The defrosting control system according to claim 2, wherein The temperature sensing pipeline is provided with a waterway temperature sensing package and an electric auxiliary heating device. The waterway temperature sensing package is arranged close to the second water pump. The waterway temperature sensing package and the electric auxiliary heating device are electrically connected to the control system respectively. When the control system obtains that the temperature value measured by the waterway 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 defrosting liquid in the temperature sensing pipeline.

4. The defrosting control system according to claim 3, wherein The temperature sensing pipeline is provided with a two-way valve, and the two-way valve is communicated between the electric auxiliary heating device and the waterway temperature sensing package. The two-way valve is electrically connected to the control system.

5. The defrosting control system according to claim 2, characterized in that, The temperature sensing pipeline is provided with a water flow switch, which 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 defrosting control system according to claim 1, wherein The outer tube outlet is communicated with a first water pump, and the first water pump is used to provide the pump pressure for defrosting under the heating condition of the defrosting control system.

7. An air conditioner, characterized in that, Including the defrosting control system according to any one of claims 3-6, further including: a traditional heat pump unit, which includes a compressor and a throttle valve. The inner tube inlet is communicated with the compressor and is used to receive the inflow of high-temperature refrigerant gas; the inner tube outlet is communicated with the throttle valve and is used to allow low-temperature refrigerant liquid to flow out.

8. A defrosting control method, characterized in that Applying the defrosting control system according to any one of claims 3-6, the defrosting control method includes: Under the heating condition, it is determined that the unit meets the defrosting condition; The control system controls the second three-way valve to reverse so that the second three-way valve blocks between the outer tube inlet and the inner tube inlet, and the high-temperature refrigerant gas flows in through the inner tube inlet to maintain the heating condition in the inner tube; The control system controls the first three-way valve to change its direction so that the first three-way valve blocks between the outer pipe inlet and the inner pipe inlet, and the defrosting liquid flows in from the outer pipe inlet to perform the defrosting process on the outer pipe.

9. The defrosting control method according to claim 8, wherein The control system controls the second three-way valve to change its direction so that the second three-way valve blocks between the outer pipe inlet and the inner pipe inlet, and the high-temperature refrigerant gas flows in from the inner pipe inlet. After the step of maintaining the heating condition in the inner pipe, the defrosting control method includes: The control system controls the second water pump to start. When the control system obtains that the temperature value measured by the waterway temperature sensor is less than the preset temperature range, the control system controls the electric auxiliary heating device to start to heat the defrosting liquid in the temperature-sensing pipeline. When the control system obtains that the temperature value measured by the waterway temperature sensor is greater than or equal to the preset temperature range, the control system controls the electric auxiliary heating device to turn off.

10. The defrost control method according to claim 9, wherein The defrosting control method includes: Determine that the condition for exiting defrosting is met. The control system controls the two-way valve to close. The control system controls the first three-way valve to change its direction. The control system controls the second three-way valve to change its direction. The control system controls the second water pump to close.

11. The defrost control method according to claim 8, characterized in that, After the step of determining that the unit meets the defrosting condition under the heating condition, before the step of the control system controlling the second three-way valve to change its direction so that the second three-way valve blocks between the outer pipe inlet and the inner pipe inlet and the high-temperature refrigerant gas flows in from the inner pipe inlet to maintain the heating condition in the inner pipe, the defrosting control method includes: The control system controls the two-way valve to open so that the second water pump, the temperature-sensing pipeline and the double-layer tube fin heat exchanger are kept in a fully connected state.

12. The defrosting control method according to claim 11, wherein After the step of the control system controlling the two-way valve to open, before the step of the control system controlling the second three-way valve to change its direction so that the second three-way valve blocks between the outer pipe inlet and the inner pipe inlet and the high-temperature refrigerant gas flows in from the inner pipe inlet to maintain the heating condition in the inner pipe, the defrosting control method includes: The control system receives the detection result of the water flow switch. When the water flow switch detects that there is water passing through in the temperature-sensing pipeline, the next step is executed.

13. The defrosting control method according to claim 8, wherein A first time interval is left between the step of the control system controlling the second three-way valve to change its direction and the step of the control system controlling the second three-way valve to change its direction.

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