Defrosting control method and device and heat pump system

Abstract

The invention discloses a defrosting control method and device and a heat pump system.The method comprises the steps that S1, a first operation parameter is detected in a defrosting mode, whether a first defrosting condition is met or not is judged, if yes, the defrosting mode continues to be operated, and if not, a heating mode continues to be operated; and S2, in the heating mode, detecting a second operation parameter and whether the second operation parameter meets a second defrosting condition or not, if yes, operating the defrosting mode and returning to the step S1, counting the number of times that the first defrosting condition is not met, and if the number of times that the first defrosting condition is not met exceeds a first preset number of times, controlling the heat pump system to stop and sending out a fault prompt. Whether the heat pump system is abnormal or not is preliminarily judged by detecting the water inlet and outlet temperature difference and the refrigerant inlet and outlet temperature difference of the water side heat exchanger in the defrosting mode, and then the abnormal condition of the heat pump system is further confirmed by combining the water inlet and outlet temperature difference of the water side heat exchanger during operation of the heating mode, so that the abnormal condition can be found in time, defrosting is stopped, and the heating efficiency is improved. And icing or damage of the water side heat exchanger is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pump units, and in particular to a defrosting control method and device and a heat pump system. Background Art

[0002] Heat pump systems are commonly equipped with a water flow switch to monitor the water flow during operation. When the water flow falls below a preset threshold, the switch triggers a protection mechanism, sending an alarm signal indicating insufficient water flow to the system, ensuring safe operation.

[0003] However, during the defrost process, if an anomaly in the heat pump system results in no water flow on the water side, and the water flow switch fails to promptly report a fault due to a malfunction or anomaly, the heat pump unit will continue to operate in normal defrost mode. In this case, due to the lack of normal water flow in the water-side heat exchanger, the refrigerant will not be able to effectively absorb the water's heat and will not fully vaporize into a gaseous state, resulting in the risk of "liquid carryover" at the compressor suction end. As the compressor continues to operate and continuously draws in insufficiently vaporized refrigerant, the refrigerant temperature and evaporation pressure in the water-side heat exchanger will continue to drop, eventually triggering the unit's low-pressure protection mechanism and causing the unit to shut down. More seriously, if the refrigerant temperature drops below freezing before the low-pressure protection mechanism is activated, the water inside the water-side heat exchanger may freeze, affecting the unit's operational stability and potentially causing irreversible damage to core components such as the water-side heat exchanger, seriously threatening the unit's overall safety. Summary of the Invention

[0004] The embodiments of the present invention provide a defrost control method, device and heat pump system, which aim to solve the problem in the prior art that when the heat pump system is abnormal and the water flow switch fails, defrosting cannot be detected and stopped in time, resulting in freezing of the water side heat exchanger and damage to the unit.

[0005] In a first aspect, an embodiment of the present invention provides a defrost control method, which is applied to a heat pump system, wherein the heat pump system includes a water-side heat exchanger, including:

[0006] S1. After the heat pump system has been operating in the defrost mode for a first predetermined time, detecting a first operating parameter of the water-side heat exchanger and determining whether the first operating parameter satisfies a first defrost condition; if so, continuing the defrost mode and completing defrost; otherwise, controlling the heat pump system to operate in the heating mode; wherein the first operating parameter includes a water inlet and outlet temperature difference and a refrigerant inlet and outlet temperature difference of the water-side heat exchanger;

[0007] S2. After the heat pump system has been running in the heating mode for a second predetermined time, the second operating parameter of the water-side heat exchanger is detected, and it is determined whether the second operating parameter meets the second defrost condition. If so, the heat pump system is controlled to run in the defrost mode and returns to step S1, and the number of times the first defrost condition is not met is counted. If the number of times the first defrost condition is not met exceeds the first preset number, the heat pump system is controlled to shut down and a fault prompt is issued, wherein the second operating parameter includes the water inlet and outlet temperature difference of the water-side heat exchanger.

[0008] In a second aspect, an embodiment of the present invention provides a defrost control device, comprising:

[0009] a first processing unit, configured to detect a first operating parameter of the water-side heat exchanger after the heat pump system has been operating in the defrost mode for a first predetermined time, and determine whether the first operating parameter satisfies a first defrost condition; if so, continue operating the defrost mode and complete defrost; if not, control the heat pump system to operate in the heating mode; wherein the first operating parameter includes a water inlet and outlet temperature difference and a refrigerant inlet and outlet temperature difference of the water-side heat exchanger;

[0010] The second processing unit is used to detect the second operating parameter of the water-side heat exchanger after the heat pump system has been running in the heating mode for a second predetermined time, and to determine whether the second operating parameter meets the second defrost condition. If so, the heat pump system is controlled to run in the defrost mode and return to step S1, and the number of times the first defrost condition is not met is counted. If the number of times the first defrost condition is not met exceeds the first preset number, the heat pump system is controlled to shut down and a fault prompt is issued, wherein the second operating parameter includes the water inlet and outlet temperature difference of the water-side heat exchanger.

[0011] In a third aspect, an embodiment of the present invention provides a heat pump system that performs a defrost operation using the defrost control method according to the first aspect.

[0012] An embodiment of the present invention provides a defrost control method, which is applied to a heat pump system, wherein the heat pump system includes a water-side heat exchanger, and includes: S1, after the heat pump system runs in a defrost mode for a first predetermined time, detecting a first operating parameter of the water-side heat exchanger, and judging whether the first operating parameter meets a first defrost condition, if so, continuing to run the defrost mode, if otherwise, controlling the heat pump system to run a heating mode; S2, after the heat pump system runs in a heating mode for a second predetermined time, detecting a second operating parameter of the water-side heat exchanger, and judging whether the second operating parameter meets a second defrost condition, if so, controlling the heat pump system to run the defrost mode and returning to step S1, and counting the number of times the first defrost condition is not met, if the number of times the first defrost condition is not met exceeds a first preset number, controlling the heat pump system to shut down and issuing a fault prompt. The present invention preliminarily determines whether the heat pump system is abnormal by detecting the water inlet and outlet temperature difference and the refrigerant inlet and outlet temperature difference of the water-side heat exchanger in the defrost mode, and then further confirms the abnormality of the heat pump system in combination with the water inlet and outlet temperature difference of the water-side heat exchanger when running in the heating mode. In this way, abnormal conditions can be discovered in time and defrosting can be terminated, thereby reducing freezing or damage to the water-side heat exchanger.

[0013] The embodiments of the present invention further provide a defrost control device and a heat pump system, which also have the above-mentioned beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 A schematic flow chart of a defrost control method provided by an embodiment of the present invention;

[0016] Figure 2 Another schematic flow chart of a defrost control method provided by an embodiment of the present invention;

[0017] Figure 3 A schematic block diagram of a defrost control device provided by an embodiment of the present invention;

[0018] Figure 4 A schematic structural diagram of a heat pump system provided in an embodiment of the present invention.

[0019] Description of reference numerals:

[0020] 1. Compressor; 2. Four-way valve; 3. Water-side heat exchanger; 4. Non-water-side heat exchanger; 5. Water inlet temperature sensor; 6. Water outlet temperature sensor; 7. Refrigerant inlet pipe sensor; 8. Refrigerant outlet pipe sensor; 9. Electronic expansion valve. DETAILED DESCRIPTION

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0022] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0023] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used in the specification and appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0024] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0025] See below Figure 1 , Figure 1 This is a flow chart of a defrost control method provided by an embodiment of the present invention. The defrost control method is applied to a heat pump system including a water-side heat exchanger, specifically comprising:

[0026] S1. After the heat pump system has been operating in the defrost mode for a first predetermined time, detecting a first operating parameter of the water-side heat exchanger and determining whether the first operating parameter satisfies a first defrost condition; if so, continuing the defrost mode and completing defrost; otherwise, controlling the heat pump system to operate in the heating mode; wherein the first operating parameter includes a water inlet and outlet temperature difference and a refrigerant inlet and outlet temperature difference of the water-side heat exchanger;

[0027] S2. After the heat pump system has been running in the heating mode for a second predetermined time, the second operating parameter of the water-side heat exchanger is detected, and it is determined whether the second operating parameter meets the second defrost condition. If so, the heat pump system is controlled to run in the defrost mode and returns to step S1, and the number of times the first defrost condition is not met is counted. If the number of times the first defrost condition is not met exceeds the first preset number, the heat pump system is controlled to shut down and a fault prompt is issued, wherein the second operating parameter includes the water inlet and outlet temperature difference of the water-side heat exchanger.

[0028] Combine Figure 2 As shown, in step S1, when the heat pump system is in the defrost mode and runs for the first predetermined time (i.e. Figure 2 After a certain time (e.g., 30 seconds), the first operating parameters of the water-side heat exchanger are detected, including the water inlet and outlet temperature differences and the refrigerant inlet and outlet temperature differences. A determination is made as to whether the first operating parameters meet a first defrost condition. If so, the system continues to operate in defrost mode until defrosting is complete. If not, an abnormality is preliminarily determined, and the heat pump system is controlled to exit defrost mode and enter heating mode to further confirm whether an abnormality exists.

[0029] In step S2, when the heat pump system is in the heating mode and operates for the second predetermined time (i.e. Figure 2 N in (for example, 60 seconds), the second operating parameters of the water-side heat exchanger are detected again, including the water inlet and outlet temperature difference of the water-side heat exchanger, to determine whether the second operating parameters detected again meet the second defrost condition. If the second defrost condition is met, the system switches to the defrost mode again, and returns to step S1 to re-determine whether the defrost is effective. At the same time, the number of times the first defrost condition is not met in historical defrost attempts is counted; if the counted number exceeds a first preset number (for example, 3 times), the heat pump system is considered abnormal, the heat pump system is controlled to shut down, and a fault prompt is issued to prompt the user to check whether the water pump, water flow switch or heat pump system pipeline is blocked or abnormal.

[0030] This embodiment introduces a judgment logic based on actual operating parameters between defrosting and heating, effectively preventing the system from continuing to erroneously defrost when there is no flow in the heat pump system and the water flow switch fails, thereby improving the safety of the heat pump system.

[0031] In one embodiment, the first defrost condition is: ΔT1>A and ΔT2<A, ΔT1 is the refrigerant inlet and outlet temperature difference, ΔT2 is the water inlet and outlet temperature difference, and A is the first temperature threshold.

[0032] In this embodiment, after the heat pump system operates in defrost mode for a certain period of time (e.g., 30 seconds), it obtains two temperature difference parameters for judgment: If the refrigerant inlet and outlet temperature difference ΔT1 is greater than the first temperature threshold A (A is in degrees Celsius, for example, A is 0°C), it indicates that the refrigerant is not fully vaporized in the water-side heat exchanger, and there is a risk of refrigerant return gas carrying liquid; at the same time, if the water inlet and outlet temperature difference ΔT2 is less than A, it indicates that the heat pump system is not effectively exchanging heat, and there may be abnormal conditions such as no water flow or insufficient water flow. Under these conditions, it can be reasonably determined that the defrost process is invalid. The system should promptly exit defrost mode and switch to heating mode to prevent further cooling of the refrigerant, which may cause ice to form in the water-side heat exchanger and damage the equipment.

[0033] In one embodiment, the second defrost condition is: B≤ΔT2≤C, ΔT2 is the water inlet and outlet temperature difference, B and C are the second temperature threshold and the third temperature threshold, respectively. After step S2, the following further steps are included:

[0034] S3. If the second defrost condition is not met, compare the relationship between ΔT2 and B and C. If ΔT2 < B, return to step S2 and count the number of times ΔT2 < B. If the number of times ΔT2 < B exceeds a second preset number, control the heat pump system to shut down and issue a fault prompt.

[0035] In this embodiment, the second defrost condition is used to determine whether the heat pump system is in a suitable heat exchange state in the current heating mode, thereby determining whether to enter the next defrost process. If the detected water inlet and outlet temperature difference ΔT2 does not meet the second defrost condition after the heat pump system is in heating mode and has been running for a second predetermined time (e.g., 60 seconds), the system further compares the water inlet and outlet temperature difference ΔT2 with the second temperature threshold B and the third temperature threshold C (B and C are both in degrees Celsius, e.g., B is 1°C and C is 8°C) to determine the specific direction of deviation.

[0036] If the judgment result is △T2<B, it means that the heat pump system may have an abnormal situation of too small flow or no water flow, and failed to form effective heat exchange, indicating that the system operation state is abnormal. At this time, the system will return to step S2, continue to operate in the heating mode for the second predetermined time, and then determine again whether the second defrost condition is met, and simultaneously record the number of times △T2<B occurs. If the continuous statistical results show that the number of times △T2<B exceeds the second preset number (for example, 3 times), the system determines that the heat pump system is in an abnormal state, and then controls the heat pump system to shut down, and issues a fault prompt, prompting the user to check the water pump, water flow switch and water pipes. Through the judgment mechanism in this embodiment, the abnormal state of the heat pump system can be accurately identified based on the actual operating parameters even if the water flow switch fails abnormally, and the system can be shut down for protection in time when it cannot effectively exchange heat, effectively avoiding the problem of freezing of the water side heat exchanger and damage to the system due to continuous operation.

[0037] In one embodiment, step S2 further includes:

[0038] S4. If the second defrost condition is not met, compare the relationship between ΔT2 and B and C. If ΔT2>C, return to step S2 and count the number of times ΔT2>C. If the number of times ΔT2>C exceeds a third preset number, control the heat pump system to shut down and issue a fault prompt.

[0039] In this embodiment, when the detected water inlet and outlet temperature difference ΔT2 does not meet the second defrost condition, the system continues to compare the relationship between the water inlet and outlet temperature difference ΔT2 and the second temperature threshold B and the third temperature threshold C to determine the deviation direction.

[0040] If the result is ΔT2 > C, it indicates that the temperature difference between the water inlet and outlet of the water-side heat exchanger is too large. This may be due to problems such as abnormally high water flow, abnormal water temperature control, or abnormal sensor accuracy, causing the system operating state to deviate from the normal heat exchange range. At this time, the system returns to step S2, continuing to operate in heating mode for a second predetermined time (for example, 60 seconds), and then retesting to determine whether the second defrost condition is met. At the same time, the number of times ΔT2 > C is counted.

[0041] If the cumulative number of times △T2>C exceeds a third preset number (for example, 3 times), the system will determine that the current heat pump system has a serious anomaly and is not suitable for continued operation. To avoid further risks, the system will control the heat pump to perform a shutdown operation and issue a fault prompt, guiding the user to inspect and maintain components such as the water pump, water flow control device, heat exchanger, and temperature sensor.

[0042] In one embodiment, detecting the first operating parameter of the water-side heat exchanger includes:

[0043] Detecting the water inlet temperature, water outlet temperature, refrigerant inlet pipe temperature, and refrigerant outlet pipe temperature of the water side heat exchanger;

[0044] Calculate the difference between the outlet water temperature and the inlet water temperature to obtain the water inlet and outlet temperature difference;

[0045] The difference between the refrigerant outlet pipe temperature and the refrigerant inlet pipe temperature is calculated to obtain the refrigerant inlet and outlet temperature difference.

[0046] In this embodiment, a water temperature sensor detects the water inlet and outlet temperatures, respectively, and the water inlet and outlet temperature difference ΔT2 can be calculated. This difference, obtained by subtracting the water inlet temperature from the outlet temperature, reflects the temperature rise of the heat pump system during the heat exchange process and is a key basis for determining whether there is effective water flow and heat exchange in the heat pump system. Secondly, a refrigerant pipe temperature sensor detects the temperature of the refrigerant as it enters and leaves the water-side heat exchanger. The refrigerant inlet and outlet temperature difference ΔT1 is calculated by subtracting the refrigerant outlet pipe temperature from the refrigerant inlet pipe temperature. This parameter can be used to evaluate the vaporization of the refrigerant in the water-side heat exchanger and thus determine the effectiveness of the defrost process.

[0047] Through the placement of these temperature sensors and the calculation of temperature differences, the system can determine two key operating parameters: the water inlet and outlet temperature difference △T2 and the refrigerant inlet and outlet temperature difference △T1. These parameters serve as the basis for determining the first and second defrost conditions during the defrost control process, providing data support for intelligent identification and protective control of the heat pump system's operating status. This detection process offers fast response and simple calculations, improving the system's ability to detect heat pump system anomalies and enhancing operational safety without relying on traditional water flow switches.

[0048] In one embodiment, the heat pump system further includes a compressor, a non-water-side heat exchanger, and a four-way valve, wherein a first end of the four-way valve is connected to an exhaust pipe of the compressor, a second end of the four-way valve is connected to a refrigerant outlet of the water-side heat exchanger, a third end of the four-way valve is connected to an intake pipe of the compressor, and a fourth end of the four-way valve is connected to the non-water-side heat exchanger. Detecting the refrigerant outlet pipe temperature of the water-side heat exchanger includes:

[0049] The refrigerant temperature between the third end of the four-way valve and the suction pipe of the compressor is detected and used as the refrigerant outlet pipe temperature.

[0050] In this embodiment, the heat pump system further includes a compressor, a non-water side heat exchanger and a four-way valve, which are used to realize the switching of the system between the heating mode and the defrost mode, and assist in the detection and judgment of the refrigerant temperature. The first end of the four-way valve is connected to the exhaust pipe of the compressor for receiving high-temperature and high-pressure refrigerant gas; the second end is connected to the refrigerant outlet of the water side heat exchanger; the third end is connected to the suction pipe of the compressor for returning the refrigerant to the compressor; and the fourth end is connected to the non-water side heat exchanger (such as a finned heat exchanger). The four-way valve switches the refrigerant flow direction by changing the internal valve core passage, thereby completing the conversion between the heating and defrost modes. Based on this structure, in order to detect the refrigerant outlet pipe temperature of the water side heat exchanger, this embodiment arranges a refrigerant temperature sensor between the third end of the four-way valve and the compressor suction pipe to collect the refrigerant temperature at this position in real time and use it as the refrigerant outlet pipe temperature of the water side heat exchanger. The temperature of the refrigerant at this position can directly reflect the state of the refrigerant after completing heat exchange in the water-side heat exchanger, especially the vaporization condition during the defrosting process, and has significant representativeness and judgment value.

[0051] Combine Figure 3 As shown, the embodiment of the present invention further provides a defrost control device, the defrost control device 300, comprising:

[0052] The first processing unit 301 is configured to detect a first operating parameter of the water-side heat exchanger after the heat pump system has been operating in the defrost mode for a first predetermined time, and determine whether the first operating parameter satisfies a first defrost condition; if so, continue to operate in the defrost mode and complete defrost; if not, control the heat pump system to operate in the heating mode; wherein the first operating parameter includes a water inlet and outlet temperature difference and a refrigerant inlet and outlet temperature difference of the water-side heat exchanger;

[0053] The second processing unit 302 is used to detect the second operating parameter of the water-side heat exchanger after the heat pump system has been running in the heating mode for a second predetermined time, and to determine whether the second operating parameter meets the second defrost condition. If so, the heat pump system is controlled to run in the defrost mode and return to step S1, and the number of times the first defrost condition is not met is counted. If the number of times the first defrost condition is not met exceeds the first preset number, the heat pump system is controlled to shut down and a fault prompt is issued, wherein the second operating parameter includes the water inlet and outlet temperature difference of the water-side heat exchanger.

[0054] In this embodiment, after the heat pump system has been running in the defrost mode for a first predetermined time, the first processing unit 301 detects the first operating parameter of the water-side heat exchanger and determines whether the first operating parameter meets the first defrost condition. If so, the defrost mode continues to run and defrost is completed. Otherwise, the heat pump system is controlled to run in the heating mode; wherein, the first operating parameter includes the water inlet and outlet temperature difference and the refrigerant inlet and outlet temperature difference of the water-side heat exchanger; the second processing unit 302 detects the second operating parameter of the water-side heat exchanger after the heat pump system has been running in the heating mode for a second predetermined time, and determines whether the second operating parameter meets the second defrost condition. If so, the heat pump system is controlled to run in the defrost mode and return to step S1, and counts the number of times the first defrost condition is not met. If the number of times the first defrost condition is not met exceeds the first preset number, the heat pump system is controlled to shut down and a fault prompt is issued, wherein, the second operating parameter includes the water inlet and outlet temperature difference of the water-side heat exchanger.

[0055] Combine Figure 4 As shown, an embodiment of the present invention further provides a heat pump system that performs a defrost operation using the defrost control method described above.

[0056] In this embodiment, the heat pump system utilizes the defrost control method described in the aforementioned embodiments of the present invention to perform defrost operations, enabling dynamic monitoring and intelligent switching of the defrost process, thereby improving the system's reliability and safety under complex operating conditions. Furthermore, if the heat pump system detects multiple consecutive defrost failures or heat exchange anomalies, it can proactively trigger shutdown protection and issue a fault prompt, guiding the user to promptly check the operating status of the system's water pump, water flow switch, and piping. This effectively prevents problems such as refrigerant failure to vaporize properly, freezing of the water-side heat exchanger, and even damage to system components caused by heat pump system anomalies and water flow detection failures.

[0057] In one embodiment, the heat pump system includes: a compressor 1, a four-way valve 2, a water-side heat exchanger 3, and a non-water-side heat exchanger 4. The first end of the four-way valve 2 is connected to the exhaust pipe of the compressor 1, the second end of the four-way valve 2 is connected to the refrigerant outlet of the water-side heat exchanger 3, the third end of the four-way valve 2 is connected to the intake pipe of the compressor 1, the fourth end of the four-way valve 2 is connected to one end of the non-water-side heat exchanger 4, and the other end of the non-water-side heat exchanger 4 is connected to the refrigerant inlet of the water-side heat exchanger 3.

[0058] In this embodiment, the four-way valve 2 serves as a key component for switching the direction of refrigerant flow. Its first end is connected to the exhaust pipe of the compressor 1 to receive the high-temperature and high-pressure refrigerant gas discharged by the compressor 1; the second end is connected to the refrigerant outlet of the water-side heat exchanger 3 (the water-side heat exchanger 3 can be a shell-and-tube heat exchanger, a shell-and-tube heat exchanger, a plate heat exchanger, etc.), that is, the refrigerant enters this port after flowing out of the water-side heat exchanger 3; the third end is connected to the suction pipe of the compressor 1 to return the low-temperature and low-pressure refrigerant gas to the compressor 1 for compression; the fourth end is connected to one end of the non-water-side heat exchanger 4 to achieve heat exchange with the ambient air. The other end of the non-water-side heat exchanger 4 is connected to the refrigerant inlet of the water-side heat exchanger 3 to form a complete refrigerant circulation channel.

[0059] In heating mode, four-way valve 2 adjusts the flow path so that the high-temperature refrigerant gas discharged from compressor 1 first enters water-side heat exchanger 3, exchanging heat with the heat pump system and thus heating the water. In defrost mode, four-way valve 2 switches the refrigerant flow direction, allowing the high-temperature refrigerant to preferentially enter non-water-side heat exchanger 4, heating this component and melting the frost. This structural arrangement enables the heat pump system to flexibly switch between defrost and heating modes, while maintaining a clear refrigerant circulation path. This facilitates effective parameter monitoring and intelligent judgment in conjunction with the defrost control method of the present invention, thereby ensuring the stability and safety of system operation.

[0060] In one embodiment, the heat pump system also includes an inlet water temperature sensor 5, an outlet water temperature sensor 6, a refrigerant inlet pipe sensor 7, and a refrigerant outlet pipe sensor 8. The inlet water temperature sensor 5 is arranged on the water inlet pipe of the water side heat exchanger 3, the outlet water temperature sensor 5 is arranged on the water outlet pipe of the water side heat exchanger 3, the refrigerant inlet pipe sensor 7 is arranged on the refrigerant inlet liquid pipe of the water side heat exchanger 3, and the refrigerant outlet pipe sensor 8 is arranged between the third end of the four-way valve 2 and the suction pipe of the compressor 1.

[0061] In this embodiment, a water inlet temperature sensor 5 is installed on the water inlet pipe of the water-side heat exchanger 3 to detect the temperature of the water entering the water-side heat exchanger 3; a water outlet temperature sensor 6 is installed on the water outlet pipe of the water-side heat exchanger 3 to detect the water temperature after heat exchange is completed. The temperature difference measured by these two sensors can be used to calculate the water inlet and outlet temperature difference, which is used to evaluate the heat exchange status of the heat pump system. A refrigerant inlet pipe sensor 7 is installed on the refrigerant inlet liquid pipe of the water-side heat exchanger 3 to detect the temperature of the refrigerant entering the water-side heat exchanger 3; a refrigerant outlet pipe sensor 8 is installed between the third end of the four-way valve 2 and the suction pipe of the compressor 1 to detect the temperature of the refrigerant after passing through the water-side heat exchanger 3 and before returning to the compressor 1. The temperature difference between these two refrigerant sensors can be used to calculate the refrigerant inlet and outlet temperature difference, thereby determining whether the refrigerant is effectively vaporized within the heat exchanger.

[0062] In one embodiment, the heat pump system further includes an electronic expansion valve 9 , which is disposed in the refrigerant circuit between the non-water-side heat exchanger 4 and the water-side heat exchanger 3 , and is used to adjust the refrigerant flow entering the water-side heat exchanger 3 .

[0063] Specifically, the electronic expansion valve 9 can dynamically adjust its opening according to the system's operating status and control strategy, thereby controlling the flow and pressure of the refrigerant entering the water-side heat exchanger 3, enabling the refrigerant to achieve a good throttling, pressure reduction, and evaporation heat absorption process within the water-side heat exchanger 3. The electronic expansion valve 9, in conjunction with the compressor 1, four-way valve 2, and various temperature sensors, not only helps maintain the heat exchange efficiency and stable operation of the heat pump system, but also provides key regulatory capabilities and refrigerant management tools for the defrost control method implemented in the present invention.

[0064] By setting the electronic expansion valve 9, the system can flexibly control the refrigerant flow according to parameters such as the refrigerant inlet and outlet temperature difference, the water inlet and outlet temperature difference, etc., to achieve a more refined heat exchange process, effectively cooperate with the switching control between the defrost mode and the heating mode, and further improve the energy saving, safety and adaptability of the overall system to complex working conditions.

[0065] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of this application, several improvements and modifications can be made to this application, and these improvements and modifications also fall within the scope of protection of the claims of this application.

[0066] It should also be noted that, in this specification, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

Claims

1. A defrost control method, applied to a heat pump system, wherein the heat pump system includes a water-side heat exchanger, characterized in that: include: S1. After the heat pump system has been operating in the defrost mode for a first predetermined time, detecting a first operating parameter of the water-side heat exchanger and determining whether the first operating parameter satisfies a first defrost condition; if so, continuing the defrost mode and completing defrost; otherwise, controlling the heat pump system to operate in the heating mode; wherein the first operating parameter includes a water inlet and outlet temperature difference and a refrigerant inlet and outlet temperature difference of the water-side heat exchanger; S2. After the heat pump system has been running in the heating mode for a second predetermined time, the second operating parameter of the water-side heat exchanger is detected, and it is determined whether the second operating parameter meets the second defrost condition. If so, the heat pump system is controlled to run in the defrost mode and returns to step S1, and the number of times the first defrost condition is not met is counted. If the number of times the first defrost condition is not met exceeds the first preset number, the heat pump system is controlled to shut down and a fault prompt is issued, wherein the second operating parameter includes the water inlet and outlet temperature difference of the water-side heat exchanger.

2. The defrost control method according to claim 1, characterized in that: The first defrost condition is: ΔT1>A and ΔT2<A, ΔT1 is the refrigerant inlet and outlet temperature difference, ΔT2 is the water inlet and outlet temperature difference, and A is the first temperature threshold.

3. The defrost control method according to claim 1, characterized in that: The second defrosting condition is: B≤ΔT2≤C, ΔT2 is the water inlet and outlet temperature difference, B and C are the second temperature threshold and the third temperature threshold respectively, and after step S2, the following further comprises: S3. If the second defrost condition is not met, compare the relationship between ΔT2 and B and C. If ΔT2 < B, return to step S2 and count the number of times ΔT2 < B. If the number of times ΔT2 < B exceeds a second preset number, control the heat pump system to shut down and issue a fault prompt.

4. The defrost control method according to claim 3, characterized in that: After step S2, the following steps are also included: S4. If the second defrost condition is not met, compare the relationship between ΔT2 and B and C. If ΔT2>C, return to step S2 and count the number of times ΔT2>C. If the number of times ΔT2>C exceeds a third preset number, control the heat pump system to shut down and issue a fault prompt.

5. The defrost control method according to claim 1, characterized in that: Detecting a first operating parameter of the water-side heat exchanger includes: Detecting the water inlet temperature, water outlet temperature, refrigerant inlet pipe temperature, and refrigerant outlet pipe temperature of the water side heat exchanger; Calculate the difference between the outlet water temperature and the inlet water temperature to obtain the water inlet and outlet temperature difference; The difference between the refrigerant outlet pipe temperature and the refrigerant inlet pipe temperature is calculated to obtain the refrigerant inlet and outlet temperature difference.

6. The defrost control method according to claim 5, characterized in that: The heat pump system further includes a compressor, a non-water side heat exchanger, and a four-way valve, wherein a first end of the four-way valve is connected to an exhaust pipe of the compressor, a second end of the four-way valve is connected to a refrigerant outlet of the water side heat exchanger, a third end of the four-way valve is connected to an intake pipe of the compressor, and a fourth end of the four-way valve is connected to the non-water side heat exchanger. Detecting the refrigerant outlet pipe temperature of the water side heat exchanger includes: The refrigerant temperature between the third end of the four-way valve and the suction pipe of the compressor is detected and used as the refrigerant outlet pipe temperature.

7. A defrost control device, characterized in that: include: a first processing unit, configured to detect a first operating parameter of the water-side heat exchanger after the heat pump system has been operating in the defrost mode for a first predetermined time, and determine whether the first operating parameter satisfies a first defrost condition; if so, continue operating the defrost mode and complete defrost; if not, control the heat pump system to operate in the heating mode; wherein the first operating parameter includes a water inlet and outlet temperature difference and a refrigerant inlet and outlet temperature difference of the water-side heat exchanger; The second processing unit is used to detect the second operating parameter of the water-side heat exchanger after the heat pump system has been running in the heating mode for a second predetermined time, and to determine whether the second operating parameter meets the second defrost condition. If so, the heat pump system is controlled to run in the defrost mode and return to step S1, and the number of times the first defrost condition is not met is counted. If the number of times the first defrost condition is not met exceeds the first preset number, the heat pump system is controlled to shut down and a fault prompt is issued, wherein the second operating parameter includes the water inlet and outlet temperature difference of the water-side heat exchanger.

8. A heat pump system, characterized in that: The defrost operation is performed using the defrost control method according to any one of claims 1 to 6.

9. The heat pump system according to claim 8, characterized in that include: A compressor, a four-way valve, a water-side heat exchanger, and a non-water-side heat exchanger, wherein the first end of the four-way valve is connected to the exhaust pipe of the compressor, the second end of the four-way valve is connected to the refrigerant outlet of the water-side heat exchanger, the third end of the four-way valve is connected to the suction pipe of the compressor, the fourth end of the four-way valve is connected to one end of the non-water-side heat exchanger, and the other end of the non-water-side heat exchanger is connected to the refrigerant inlet of the water-side heat exchanger.

10. The heat pump system according to claim 9, characterized in that It also includes an inlet water temperature sensor, an outlet water temperature sensor, a refrigerant inlet pipe sensor, and a refrigerant outlet pipe sensor. The inlet water temperature sensor is arranged on the water inlet pipe of the water side heat exchanger, the outlet water temperature sensor is arranged on the water outlet pipe of the water side heat exchanger, the refrigerant inlet pipe sensor is arranged on the refrigerant inlet liquid pipe of the water side heat exchanger, and the refrigerant outlet pipe sensor is arranged between the third end of the four-way valve and the suction pipe of the compressor.

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