Air-cooled cold water heat pump system, control method, equipment and medium thereof

Abstract

This application relates to an air-cooled chilled water heat pump system and its control method, equipment, and medium. The system includes: a compressor, a four-way valve, a vapor-liquid separator, a finned heat exchanger, an electronic expansion valve, a plate heat exchanger, a three-pipe receiver, and a solenoid valve. The solenoid valve is connected to the plate heat exchanger and the three-pipe receiver; the three-pipe receiver is also connected to the plate heat exchanger and the electronic expansion valve. When the system is in heating mode, the solenoid valve is closed, and the receiver balances differences in refrigerant circulation. When the system is in stable cooling mode, the solenoid valve is closed, and the receiver ensures that the liquid entering the plate heat exchanger's liquid pipe is saturated liquid refrigerant. When the system is in cooling start-up, heating defrosting operation, or abnormal cooling mode, the solenoid valve opens, connecting the bypass flow path to reduce the refrigerant flow to the plate heat exchanger. This reduces the amount of refrigerant entering the plate heat exchanger during non-steady-state conditions, preventing freezing due to excessively low pressure, and improves refrigerant distribution uniformity and heat exchange efficiency during steady-state conditions.

Description

Technical Field

[0001] This application relates to the field of central air conditioning technology in the energy-saving and environmental protection industry, and in particular to an air-cooled chilled water heat pump system and its control method, equipment and medium. Background Technology

[0002] Currently, air-cooled chilled water heat pump central air conditioning systems are widely used in commercial buildings, residences, and other locations as an important form of comfort air conditioning. In related technologies, a heat transfer system using water as the refrigerant is constructed through the coordinated operation of a compressor, four-way valve, finned heat exchanger, electronic expansion valve, and plate heat exchanger. Specifically, this system covers the entire process from cooling to heating, with plate heat exchangers being the preferred choice for evaporator selection due to their high heat exchange efficiency and compact structure.

[0003] However, in air-cooled chilled water heat pump systems in related technologies, the plate heat exchanger uses a thin plate structure, resulting in narrow flow channels. Under non-steady-state operating conditions such as cooling start-up and heating switching defrosting, sudden changes in system state cause the evaporation temperature to drop rapidly. Directly adopting conventional control strategies does not effectively address the risk of plate heat exchanger freezing, which may lead to ice expansion and cracking on the water side of the plate heat exchanger, thereby affecting the system reliability and service life. Summary of the Invention

[0004] To address the technical problem of plate heat exchangers freezing under unsteady operating conditions, which could lead to ice expansion and cracking on the water side, this application provides an air-cooled chilled water heat pump system and its control method, equipment, and medium. The specific technical solution is as follows: In a first aspect, this application provides an air-cooled chilled water heat pump system, the system comprising: Compressor, four-way valve, vapor-liquid separator, finned heat exchanger, electronic expansion valve, plate heat exchanger, three-pipe liquid receiver, and solenoid valve; among which, The solenoid valves are connected to the gas pipe of the plate heat exchanger and the three-pipe liquid reservoir, respectively. The three-pipe liquid reservoir is also connected to the liquid pipe of the plate heat exchanger and the electronic expansion valve, respectively. When the system is in heating mode, the solenoid valve is closed, and the three-pipe liquid receiver is used to balance the difference in refrigerant circulation in the system. When the system is in a stable cooling state, the solenoid valve is closed, and the three-pipe liquid receiver is used to ensure that the liquid entering the liquid pipe is saturated liquid refrigerant; When the system is in cooling start-up, heating conversion defrosting operation, or cooling abnormal state, the solenoid valve opens, connecting the bypass flow path to reduce the refrigerant flow of the plate heat exchanger.

[0005] In one optional embodiment, the compressor is connected to port D of the four-way valve and the vapor-liquid separator, respectively; ports C, S, and E of the four-way valve are connected to the plate heat exchanger, the vapor-liquid separator, and the finned heat exchanger, respectively; and the finned heat exchanger is connected to the three-pipe liquid receiver via the electronic expansion valve.

[0006] In one optional embodiment, the three-pipe reservoir includes pipe I, pipe II, and pipe III; wherein the first ends of pipe I and pipe II are both located at the bottom of the three-pipe reservoir, and the first end of pipe III is located at the top of the three-pipe reservoir; the second end of pipe I is connected to the electronic expansion valve, the second end of pipe II is connected to the plate heat exchanger, and the second end of pipe III is connected to the solenoid valve.

[0007] In one optional implementation, when the system is in cooling mode, ports D and E of the four-way valve are connected, and ports C and S of the four-way valve are connected; when the system is in heating mode, ports D and C of the four-way valve are connected, and ports E and S of the four-way valve are connected. Secondly, this application provides a control method for an air-cooled chilled water heat pump system, applied to any of the air-cooled chilled water heat pump systems described in the first aspect above, the method comprising: The detection system is checked to see if it is in a non-steady-state operating state, wherein the non-steady-state operating state includes cooling start-up, heating start-up with four-way valve reversal, defrosting switching, and abnormal water flow. When the unsteady operating state is detected, the solenoid valve is opened to allow the refrigerant to pass through the bypass path to reduce the amount of refrigerant entering the plate heat exchanger. The detection system is checked to see if it has returned to a steady-state operating state, wherein the steady-state operating state includes the low-pressure saturation temperature reaching a safe range and the water flow returning to normal; When the steady-state operation is detected, the solenoid valve is closed to allow the refrigerant to enter the plate heat exchanger normally for heat exchange.

[0008] In an optional implementation, the detection system for whether it is in a non-steady-state operation includes: detecting whether the compressor's operating frequency is greater than zero and the four-way valve is on the cooling side; if so, it is determined to be in a cooling start state; detecting whether the compressor's operating frequency is greater than zero and whether the four-way valve has switched from the cooling side to the heating side; if so, it is determined to be in a heating start state and the four-way valve is in a reversing state; when the system is in a heating state and the defrosting conditions are met, detecting whether the four-way valve has switched from the heating side to the cooling side; if so, it is determined to be in a defrosting switching state; when the system is in a cooling state, detecting whether the water flow switch is open or whether the low-pressure saturation temperature is less than or equal to a preset constant C; if so, it is determined to be in a water flow abnormal state.

[0009] In an optional implementation, the detection system for whether it has returned to a steady-state operating state includes: after the compressor operating frequency is greater than zero and the solenoid valve is open, calculating in real time the difference between the low-pressure saturation temperature and the outlet water temperature; if the difference is less than a preset constant A, then determining that the system has returned to a steady-state operating state after the cooling start-up, wherein the preset constant A is positively correlated with the heat exchange efficiency of the plate heat exchanger.

[0010] In an optional implementation, the detection system for whether it has returned to a steady-state operating state further includes: after the four-way valve switches to the heating side and the solenoid valve opens, detecting the saturation temperature corresponding to the high-pressure sensor in real time; if the saturation temperature is greater than a preset constant B, it is determined that the system has returned to a steady-state operating state after the heating start-up and the four-way valve switching, wherein the preset constant B is negatively correlated with the thickness of the heat exchanger plates of the plate heat exchanger.

[0011] In an optional implementation, the detection system for whether it has returned to a steady-state operating state further includes: when the system is in defrost mode, detecting the low-pressure saturation temperature in real time; if the low-pressure saturation temperature is greater than the preset constant B, or the four-way valve switches from the cooling side back to the heating side, then it is determined that the system has returned to a steady-state operating state after the defrost switch or has exited the defrost mode.

[0012] In an optional implementation, the detection system for whether it has returned to a steady-state operating state further includes: when the water flow switch changes from open to closed and the low-pressure saturation temperature is greater than the preset constant B, determining that the system has returned to a steady-state operating state after the abnormal recovery of water flow; if the compressor operating frequency drops to zero, determining that the system is in a shutdown state and closing the solenoid valve.

[0013] In an optional implementation, the method further includes: keeping the solenoid valve closed when the system is in a stable cooling operation state, so that the liquid refrigerant in the three-pipe receiver enters from pipe II and is distributed to each channel for evaporation and heat absorption; and balancing the difference in refrigerant circulation between the cooling mode and the heating mode of the system through the receiver.

[0014] Thirdly, an electronic device is also provided, including a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; When the processor executes a program stored in the memory, it implements the control method of the air-cooled chilled water heat pump system described in any of the second aspects above.

[0015] Fourthly, a storage medium is also provided, wherein the storage medium stores instructions that, when executed on a computer, cause the computer to perform the control method of any of the air-cooled chilled water heat pump systems described in the second aspect above.

[0016] Fifthly, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute the control method for the air-cooled chilled water heat pump system described in any of the second aspects above.

[0017] Compared with the prior art, the technical solution provided in this application has the following advantages: The air-cooled chilled water heat pump system includes: a compressor, a four-way valve, a vapor-liquid separator, a finned heat exchanger, an electronic expansion valve, a plate heat exchanger, a three-pipe liquid receiver, and a solenoid valve; wherein, the solenoid valve is connected to the gas pipe of the plate heat exchanger and the three-pipe liquid receiver respectively; the three-pipe liquid receiver is also connected to the liquid pipe of the plate heat exchanger and the electronic expansion valve respectively; when the system is in heating mode, the solenoid valve is closed, and the three-pipe liquid receiver is used to balance the difference in refrigerant circulation volume in the system; when the system is in stable cooling mode, the solenoid valve is closed, and the three-pipe liquid receiver is used to ensure that the liquid entering the plate heat exchanger is saturated liquid refrigerant; when the system is in cooling start-up, heating conversion defrosting operation, or cooling abnormal state, the solenoid valve is opened, connecting the bypass flow path to reduce the refrigerant flow of the plate heat exchanger. Therefore, compared with conventional systems, this application adds a three-pipe liquid receiver and a solenoid valve. During system heating, the solenoid valve is closed, and the added receiver balances the difference in refrigerant circulation between cooling and heating modes. During stable cooling operation, the solenoid valve remains closed, and the added receiver ensures that the refrigerant entering the plate heat exchanger's liquid pipe is saturated liquid. Compared to the two-phase state after throttling, the pure liquid state is more evenly distributed in the plate heat exchanger, resulting in higher heat exchange efficiency. However, during non-steady-state conditions such as cooling start-up, heating defrosting operation, or refrigeration system malfunctions, opening the added solenoid valve effectively adds a bypass path, reducing the refrigerant flow in the plate heat exchanger. This prevents excessively low pressure caused by system fluctuations, which could lead to freezing on the water side of the plate heat exchanger. Therefore, this application can prevent plate heat exchanger freezing due to excessively low pressure, improve refrigerant distribution uniformity in steady-state conditions, and increase heat exchange efficiency. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0021] Figure 1 A schematic diagram of the structure of an air-cooled chilled water heat pump system provided in an embodiment of this application; Figure 2 A schematic diagram of a three-pipe liquid reservoir provided in this application embodiment; Figure 3 A schematic diagram of an air-cooled chilled water heat pump system in heating mode provided for an embodiment of this application; Figure 4 A schematic diagram of an air-cooled chilled water heat pump system in a cooling mode provided in an embodiment of this application; Figure 5 This is a schematic diagram illustrating the implementation process of a control method for an air-cooled chilled water heat pump system provided in an embodiment of this application. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] The following disclosure provides numerous different embodiments or examples for implementing various structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples. Such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0024] For ease of description, spatial relative terms may be used in the text to describe the relative position or movement of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "front," "back," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure undergoes a positional flip, orientation change, or change of motion, these directional indications will change accordingly. For instance, an element described as "below other elements or features" or "below other elements or features" will subsequently be oriented "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0025] To address the technical problem in related technologies where plate heat exchangers are at risk of freezing under non-steady-state operating conditions, which may lead to ice expansion and cracking on the water side, this application proposes an air-cooled chilled water heat pump system and its control method, equipment, and medium. In non-steady-state conditions, the amount of refrigerant entering the plate heat exchanger is reduced to avoid freezing due to excessively low pressure. In steady-state conditions, the uniformity of refrigerant distribution is improved, thereby increasing heat exchange efficiency.

[0026] like Figure 1 The diagram shown is a structural schematic of an air-cooled chilled water heat pump system provided in an embodiment of this application. The system includes: a compressor 1, a four-way valve 2, a vapor-liquid separator 3, a finned heat exchanger 4, an electronic expansion valve 5, a plate heat exchanger 6, a three-pipe liquid receiver 7, and a solenoid valve 8.

[0027] Among them, the solenoid valve 8 is connected to the gas pipe of the plate heat exchanger 6 and the three-pipe liquid reservoir 7 respectively.

[0028] The three-pipe liquid receiver 7 is also connected to the liquid pipe of the plate heat exchanger 6 and the electronic expansion valve 5, respectively.

[0029] When the air-cooled chilled water heat pump system is in heating mode, the solenoid valve 8 is closed, and the three-pipe liquid receiver 7 is used to balance the difference in the refrigerant circulation volume of the system.

[0030] When in a stable cooling state, the solenoid valve 8 is closed, and the three-pipe liquid receiver 7 is used to ensure that the liquid entering the liquid pipe of the plate heat exchanger 6 is saturated liquid refrigerant.

[0031] When the system is in cooling start-up, heating conversion defrosting operation, or cooling abnormal state, solenoid valve 8 opens, connecting the bypass flow path to reduce the refrigerant flow of plate heat exchanger 6.

[0032] Specifically, such as Figure 1 As shown, this application adds a three-pipe liquid receiver 7 and a solenoid valve 8 to the air-cooled chilled water heat pump system. One end of the solenoid valve 8 is connected to the gas pipe of the plate heat exchanger 6, and the other end is connected to the three-pipe liquid receiver 7. The three-pipe liquid receiver 7 is also connected to the liquid pipe of the plate heat exchanger 6. Therefore, when the solenoid valve 8 is in the open state, the branch where the solenoid valve 8 is located constitutes the bypass flow path of the plate heat exchanger 6.

[0033] In one embodiment of this application, reference continues to be made to... Figure 1 The compressor 1 is connected to port D of the four-way valve 2 and the vapor-liquid separator 3. Port C of the four-way valve 2 is connected to the plate heat exchanger 6, port S is connected to the vapor-liquid separator 3, and port E is connected to the finned heat exchanger 4.

[0034] The finned heat exchanger 4 is connected to the three-pipe liquid reservoir 7 via an electronic expansion valve 5. The finned heat exchanger 4 includes a fan.

[0035] In one embodiment of this application, the three-tube liquid reservoir 7 includes tube I, tube II, and tube III. Wherein, as... Figure 2 As shown, the first ends of tubes I and II of the three-pipe reservoir 7 are both at the bottom of the reservoir, and the first end of tube III is at the top of the three-pipe reservoir.

[0036] The second end of pipe I of the three-pipe liquid receiver 7 is connected to the electronic expansion valve 5, the second end of pipe II is connected to the plate heat exchanger 6, and the second end of pipe III is connected to the solenoid valve 8. That is, a solenoid valve 8 is installed between pipe III and the gas pipe of the plate heat exchanger 6, and the solenoid valve 8 can control the on / off of the connection between pipe III and the plate heat exchanger 6.

[0037] In one embodiment of this application, when the system is in cooling mode, ports D and E of the four-way valve 2 are connected, and ports C and S of the four-way valve 2 are connected; when the system is in heating mode, ports D and C of the four-way valve 2 are connected, and ports E and S of the four-way valve 2 are connected.

[0038] Specifically, the four-way valve 2 can be switched to cooling mode (i.e., using its internal slider) Figure 3 As shown, ports D and E are connected, and ports C and S are connected), or heating mode (i.e. Figure 4 As shown, ports D and C are connected, and ports E and S are connected.

[0039] Therefore, based on the above system structure, the solenoid valve 8 can be controlled to open or close under different conditions to suppress the risk of water-side freezing of the plate heat exchanger during unsteady operation, thereby improving system reliability and enhancing refrigerant distribution uniformity, thus increasing heat exchange efficiency. When the system is heating, the solenoid valve 8 is closed, and the three-pipe receiver 7 balances the difference in refrigerant circulation between cooling and heating. When the system is running stably in cooling mode, the solenoid valve 8 is closed, and the three-pipe receiver 7 ensures that the liquid entering the plate heat exchanger's liquid pipe is saturated liquid refrigerant. Compared to the two-phase state after throttling, the pure liquid state is more evenly distributed in the plate heat exchanger, resulting in higher heat exchange efficiency. During cooling start-up, heating transition defrosting operation, or refrigeration system malfunctions, the solenoid valve 8 opens, acting as a bypass path to reduce the refrigerant flow in the plate heat exchanger, preventing excessively low pressure caused by system fluctuations and the resulting risk of water-side freezing.

[0040] Based on the above embodiments, in order to more clearly illustrate the specific working process of the air-cooled chilled water heat pump system of this application in practical applications, the following is an example of a control method for an air-cooled chilled water heat pump system proposed in this application. This method is applied to the air-cooled chilled water heat pump system as described above, that is, the following control method is performed on the system.

[0041] Figure 5 A schematic diagram illustrating the implementation flow of a control method for an air-cooled chilled water heat pump system provided in this application embodiment is shown below. Figure 5 As shown, the method includes the following steps: Step S101: Detect whether the system is in a non-steady-state operating state. The non-steady-state operating state includes cooling start-up, heating start-up with four-way valve reversal, defrosting switching, and abnormal water flow.

[0042] It should be noted that during the operation of an air-cooled chilled water heat pump system, the freezing risk of the plate heat exchanger mainly stems from the sharp drop in refrigerant side temperature when the system is in an unsteady operating state. Therefore, it is necessary to monitor and judge the operating status of the system in real time to identify transient or abnormal operating conditions that may induce freezing risk.

[0043] Specifically, by collecting key operating parameters or status signals of the system, such as the operating frequency of the compressor, the reversing position of the four-way valve, the low-pressure side pressure or saturation temperature, and the on / off state of the water flow switch, and comparing them with preset thresholds or logic conditions, it can be determined whether the system is currently in a non-steady-state operating state.

[0044] The unsteady operating state includes various situations such as system startup, mode switching, defrosting process, and abnormal water flow. These situations may cause refrigerant flow lag, sudden pressure drop, or sudden change in heat exchange conditions, which may cause the refrigerant temperature in the plate heat exchanger to drop below the freezing point, posing a freezing threat to the water side.

[0045] As one implementation method, the system can be comprehensively judged to determine whether it has entered a non-steady-state operating state by detecting conditions such as whether the compressor operating frequency is greater than zero, whether the four-way valve has reversed, whether the low-pressure saturation temperature is lower than the safety threshold, or whether the water flow switch is disconnected, thereby providing an accurate triggering basis for subsequent anti-freeze control.

[0046] Therefore, this step, by identifying in real time and accurately whether the system is in a non-steady-state operating state, can provide reliable triggering conditions for subsequent bypass protection control, thereby intervening in a timely manner in the early stage when the plate heat exchanger faces the risk of freezing, effectively avoiding damage to the heat exchanger structure due to water-side ice expansion caused by excessively low refrigerant side temperature, and significantly improving the operational reliability and safety of the system under non-steady-state conditions.

[0047] Step S102: When an unsteady operating state is detected, the solenoid valve is opened to allow the refrigerant to pass through the bypass path to reduce the amount of refrigerant entering the plate heat exchanger.

[0048] Specifically, when the system is detected to be in a non-steady-state operating condition, a bypass flow path is established by controlling the opening of the solenoid valve, allowing the refrigerant to be diverted through this bypass flow path, thereby reducing the amount of refrigerant entering the plate heat exchanger. This bypass flow path is connected in parallel with the refrigerant inlet of the plate heat exchanger, enabling it to guide some refrigerant to the compressor suction side or the receiver during moments of drastic fluctuations in system pressure or flow, preventing a large influx of low-temperature, low-pressure refrigerant into the plate heat exchanger and causing a sudden drop in its internal evaporation temperature. By adjusting the opening and closing of the bypass flow path, the distribution ratio of refrigerant between the plate heat exchanger and the bypass path can be actively intervened, maintaining the refrigerant-side pressure and temperature within a safe range during non-steady-state periods, and preventing water-side freezing and expansion due to excessive refrigerant evaporation and heat absorption.

[0049] As one implementation method, under non-steady-state conditions such as cooling start-up, heating start-up reversal, defrosting switching, or abnormal water flow, after the solenoid valve opens, the refrigerant in the receiver flows out from pipes II and III simultaneously. Among them, pipe III is directly connected to the compressor suction side to form a bypass circuit, thereby reducing the refrigerant flow rate entering the plate heat exchanger through pipe II and suppressing further reduction of the refrigerant side pressure in the plate heat exchanger.

[0050] Therefore, this step, by actively diverting the refrigerant, effectively suppresses the excessive drop in refrigerant-side pressure in the plate heat exchanger during non-steady-state operation, avoids water-side freezing caused by the evaporation temperature falling below the freezing point, significantly improves the system's anti-freeze reliability during sudden changes in operating conditions, and does not rely on the delayed judgment of traditional flow switches or low-pressure protection, resulting in a faster response.

[0051] Step S103: Detect whether the system has returned to a steady-state operating state, wherein the steady-state operating state includes the low-pressure saturation temperature reaching a safe range and the water flow returning to normal.

[0052] Specifically, this step, checking whether the system has returned to a steady-state operating condition, is a process based on key parameters reflecting the system's thermal balance and safety. This process involves continuously monitoring operating indicators directly related to the freezing risk of the plate heat exchanger, such as refrigerant-side pressure or temperature parameters and water-side flow status, to determine whether the system has moved out of unsteady-state conditions and entered a stable phase capable of safely handling normal heat exchange loads.

[0053] Specifically, when the low-pressure side pressure or temperature falls below the safety threshold due to system startup, reversal, or abnormal disturbance, the solenoid valve opens to bypass the refrigerant. As the system circulation is gradually established or external conditions improve, the low-pressure side parameters will gradually rise. When they rise above the preset safety threshold, it indicates that the refrigerant temperature inside the plate heat exchanger no longer poses a freezing threat to the water side, and the system is ready to resume the normal heat exchange path.

[0054] Meanwhile, water flow rate, as another key factor affecting heat exchange balance, also signifies that the system has escaped the risk of freezing due to insufficient heat exchange when it recovers from an abnormally low state to the normal range. Therefore, the determination of steady-state recovery can be based on the comparison between the low-pressure saturation temperature and the preset safety threshold, or on the normalization state of the water flow rate detection signal.

[0055] As one implementation method, the determination process can be specifically manifested as follows: when the low-pressure saturation temperature rises to a level greater than the preset constant B, or when the water flow switch returns from the open state to the closed state and the low-pressure saturation temperature is simultaneously greater than B, it is confirmed that the system has returned to a steady-state operating state.

[0056] Therefore, this step establishes a steady-state recovery judgment mechanism based on key operating parameters to ensure that the solenoid valve closes only when the system truly meets the conditions for safe operation. This avoids premature closure of the solenoid valve, which could expose the plate heat exchanger to the risk of freezing again, or delayed closure of the solenoid valve, which could affect the system's heat exchange efficiency. This achieves a precise balance between anti-freeze protection and normal operation.

[0057] Step S104: When a steady-state operating condition is detected, the solenoid valve is closed to allow the refrigerant to enter the plate heat exchanger normally for heat exchange.

[0058] Specifically, when the system recovers from a non-steady-state operation to a steady-state operation, the bypass flow path must be terminated promptly to allow the refrigerant to resume normal heat exchange via the plate heat exchanger, ensuring efficient and stable system operation. The core of this step lies in determining whether the risk of freezing has been eliminated based on real-time monitoring of system operating parameters, thereby controlling the closing action of the solenoid valve.

[0059] Specifically, the criteria for determining steady-state operation include, but are not limited to: the low-pressure saturation temperature rising above a preset safety threshold, or the water flow rate returning to normal range, or system pressure, temperature, and other parameters meeting preset stability conditions. When any of the above steady-state conditions is met, it indicates that the refrigerant-side temperature in the plate heat exchanger has returned to a safe level, and the risk of water-side icing has been eliminated. At this time, the control solenoid valve closes, cutting off the bypass flow path, allowing all the refrigerant to exchange heat through the normal flow path of the plate heat exchanger.

[0060] As one implementation method, during the cooling start-up process, when the difference between the outlet water temperature and the low-pressure saturation temperature is less than a preset constant A, the system is determined to be stable, and the solenoid valve is closed. During the heating start-up switching process, when the saturation temperature corresponding to the high-pressure saturation pressure is greater than a preset constant B, the solenoid valve is closed. During the defrosting switching process, when the low-pressure saturation temperature is greater than the preset constant B or the four-way valve switches from cooling to heating, the solenoid valve is closed. When the water flow is abnormal during cooling operation, when the water flow switch is turned on and the low-pressure saturation temperature is greater than the preset constant B, or when the compressor stops running, the solenoid valve is closed. This step ensures that the bypass flow path is only used during non-steady-state periods, and the normal heat exchange function of the plate heat exchanger is restored in a timely manner after steady-state operation.

[0061] Therefore, through the above control, the bypass flow path can be closed in time after the system recovers stability, avoiding uneven refrigerant distribution and heat exchange efficiency reduction caused by the bypass. This ensures the reliability of the plate heat exchanger's antifreeze function while maintaining the system's efficient operation and improving overall energy efficiency and operational stability.

[0062] The following describes the specific implementation process of each step in the control method of the air-cooled chilled water heat pump system of this application using several specific embodiments.

[0063] In this embodiment, the specific implementation of detecting whether the system is in a non-steady-state operation state in step S101 is as follows. First, the current operating frequency of the compressor is obtained through the compressor operating frequency detection module, and at the same time, the position state of the slider inside the four-way valve is obtained through the four-way valve status detection module. This position state indicates that the four-way valve is currently in the refrigeration side connection mode (i.e., port D is connected to port E, and port C is connected to port S) or the heating side connection mode (i.e., port D is connected to port C, and port E is connected to port S).

[0064] When the compressor operating frequency is detected to be greater than zero and the four-way valve slider is located on the refrigeration side, the system is determined to be in the refrigeration start state. At this time, a refrigeration start flag signal is output, which serves as the control command to trigger the opening of the solenoid valve in subsequent steps.

[0065] When the four-way valve is detected to switch from the cooling side to the heating side, that is, when the four-way valve slider switches from the DE-CS connection mode to the DC-ES connection mode, the system is determined to be in the heating start reversal state, and a heating start reversal flag signal is output, which also triggers the solenoid valve to open.

[0066] When the four-way valve is detected to switch from the heating side to the cooling side, that is, when the four-way valve slider switches from the DC-ES connection mode to the DE-CS connection mode, the system is determined to be in the defrost switching state, and a defrost switching flag signal is output to trigger the solenoid valve to open.

[0067] In addition, the on / off status of the water flow switch is obtained through a water flow switch detection module. This water flow switch is installed in the water pipeline to detect whether the water flow is normal. Simultaneously, a low-pressure sensor detects the system's low-pressure and calculates the corresponding low-pressure saturation temperature based on the refrigerant's physical properties. When the water flow switch is open, or the low-pressure saturation temperature is less than or equal to a preset constant C, the system is determined to be in an abnormal water flow state, outputting a water flow abnormality flag signal and triggering the solenoid valve to open. The preset constant C is a positive number greater than the refrigeration low-pressure protection value and less than a preset constant B. Its specific value is preset based on the heat exchange efficiency of the plate heat exchanger and the system design parameters; for example, it can be set to a value between 2°C and 5°C to characterize the system in a sub-optimal refrigeration operating state.

[0068] The four decision sub-steps are independent of each other. The output flag signal of any sub-step indicates that the system is in an unsteady state, thereby driving the solenoid valve to open to bypass the refrigerant, reduce the amount of refrigerant entering the plate heat exchanger, and avoid the risk of plate heat exchanger freezing.

[0069] Therefore, through the above specific implementation methods, this embodiment can accurately identify four unsteady operating conditions: cooling start-up, heating start-up reversal, defrosting switching, and abnormal water flow. It can also promptly trigger the solenoid valve to open for each operating condition, thereby effectively suppressing the risk of water-side freezing of the plate heat exchanger when the system state changes abruptly, and improving the reliability and safety of system operation.

[0070] In this embodiment, for the unsteady operating state after heating starts and the four-way valve switches, when this state is detected, the solenoid valve is controlled to open to form a bypass flow path. The specific implementation method is as follows.

[0071] First, the system reads the high-temperature, high-pressure gaseous refrigerant output from the compressor's exhaust port. This refrigerant, after passing through a four-way valve, enters two branches formed by the gas pipe and liquid pipe of the plate heat exchanger. Part of the refrigerant enters directly through the gas pipe of the plate heat exchanger into pipe III of the three-pipe receiver, located at the top of the receiver, where it enters the upper space in gaseous form. The other part of the refrigerant enters through the liquid pipe of the plate heat exchanger into pipe II of the three-pipe receiver, which extends to the bottom of the receiver, where it enters the lower part of the receiver in either liquid or gas-liquid two-phase form. The two refrigerant streams mix inside the receiver. Due to the heat and mass exchange between the gaseous refrigerant introduced through pipe III and the refrigerant introduced through pipe II, the pressure and temperature within the receiver tend to reach equilibrium.

[0072] Then, the mixed refrigerant flows out from receiver I pipe, which also extends to the bottom of the receiver to ensure that the refrigerant flowing out is saturated liquid or nearly saturated liquid. The refrigerant is then transported through receiver I pipe to the electronic expansion valve for throttling and pressure reduction.

[0073] Through the above pathway, the refrigerant that would otherwise have all entered the plate heat exchanger is diverted to the receiver, significantly reducing the actual amount of refrigerant entering the plate heat exchanger. This avoids the risk of water-side freezing caused by a large amount of low-temperature refrigerant entering the plate heat exchanger before the compressor pressure ratio is fully established and the exhaust temperature has risen. In the initial stage after the heating start-up reversal, the solenoid valve remains open until the saturation pressure P detected by the high-pressure sensor is reached. 高压 When the pressure is greater than the preset constant B, it indicates that the system pressure ratio has been established and the exhaust temperature has risen to a safe level. At this time, the solenoid valve is closed, and the refrigerant resumes its normal path, that is, it enters the plate heat exchanger through the gas pipe of the compressor, condenses and releases heat in the plate heat exchanger, then enters the liquid receiver II pipe through the liquid pipe of the plate heat exchanger, and finally flows out from the I pipe to the electronic expansion valve.

[0074] This bypass flow path, through the coordinated action of a three-pipe liquid receiver and a solenoid valve, enables dynamic switching of the refrigerant flow direction, effectively suppressing the risk of plate heat exchangers freezing during unsteady-state operation.

[0075] Therefore, this embodiment introduces a bypass flow path consisting of a three-pipe liquid receiver and a solenoid valve to actively divert the refrigerant under non-steady-state conditions such as heating start-up reversal, reducing the amount of refrigerant entering the plate heat exchanger. This avoids water-side freezing and expansion damage caused by excessively low pressure or a sudden drop in refrigerant temperature, significantly improving the system's operational reliability and safety under harsh conditions.

[0076] In this embodiment, step S103, which involves detecting whether the system has returned to a steady-state operating state, includes multiple determination methods, each corresponding to different non-steady-state operating scenarios. For the steady-state determination after cooling startup, the system acquires the low-pressure saturation temperature detected by the low-pressure sensor and the outlet water temperature detected by the outlet water temperature sensor in real time, and calculates the difference between the two. When the compressor operating frequency is greater than zero and the solenoid valve is open, if the difference is less than a preset constant A, it is determined that the system has returned to the steady-state operating state after cooling startup. The preset constant A is positively correlated with the heat exchange efficiency of the plate heat exchanger; that is, the higher the heat exchange efficiency, the larger the value of A, and vice versa.

[0077] For steady-state determination after the heating start-up reversal, the system monitors the saturation temperature corresponding to the high-pressure sensor in real time after the four-way valve switches to the heating side and the solenoid valve opens. If the saturation temperature is greater than the preset constant B, the system is determined to have recovered to the steady-state operation state after the heating start-up reversal. The preset constant B is negatively correlated with the thickness of the heat exchanger plate, that is, the thicker the heat exchanger plate, the smaller the value of B, and the lower the risk of freezing.

[0078] For the steady-state determination after defrosting switching, when the four-way valve switches from the heating side to the cooling side and the solenoid valve opens, the system monitors the low-pressure saturation temperature in real time. If the low-pressure saturation temperature is greater than the preset constant B, or the four-way valve switches from the cooling side back to the heating side, it is determined that the system has returned to the steady-state operation state after defrosting switching.

[0079] For steady-state determination after abnormal water flow recovery, the system detects the status of the flow switch and the low-pressure saturation temperature. When the flow switch changes from open to closed and the low-pressure saturation temperature is greater than the preset constant B, the system is determined to have recovered to the steady-state operating state after the abnormal water flow recovery. In addition, if the compressor operating frequency drops to zero, it is directly determined to be in a steady-state operating state. Once the above determination conditions are met, the system outputs a steady-state determination signal, which then controls the solenoid valve to close, allowing the refrigerant to enter the plate heat exchanger normally for heat exchange.

[0080] Therefore, this embodiment sets precise steady-state judgment conditions for different unsteady-state scenarios and introduces preset constants A and B related to the characteristics of the heat exchanger, thereby achieving accurate identification of the system recovery state and avoiding misjudgment or delay. This ensures the anti-freezing effect while optimizing the stability of system operation and heat exchange efficiency.

[0081] In this embodiment, when the system detects that it has returned to a steady-state operating state, it controls the solenoid valve to close, allowing the refrigerant to enter the plate heat exchanger normally for heat exchange.

[0082] Specifically, this process involves the precise switching of the refrigerant flow path. First, the control unit receives feedback signals from the low-pressure sensor or the water flow switch. When it is determined that the low-pressure saturation temperature has risen above the safe threshold, or the water flow has returned to normal, it is confirmed that the system has escaped the risk of unsteady state.

[0083] Subsequently, the control unit sends a shut-off command to the solenoid valve. After the solenoid valve closes, the refrigerant passage that was originally via the bypass path (i.e., from the plate heat exchanger gas pipe through the solenoid valve to the receiver III pipe) is cut off. At this time, the refrigerant flow path is redirected back to the main circulation loop.

[0084] Specifically, the high-temperature, high-pressure gaseous refrigerant discharged from the compressor outlet passes through a four-way valve and flows to either a finned heat exchanger or a plate heat exchanger, depending on the system's current operating mode (cooling or heating). In cooling mode, the refrigerant condenses in the finned heat exchanger, then undergoes throttling and pressure reduction via an electronic expansion valve, becoming a low-temperature, low-pressure gas-liquid two-phase state before entering the plate heat exchanger for evaporation and heat absorption. In heating mode, the refrigerant directly enters the plate heat exchanger for condensation and heat release. With the solenoid valve closed, the only path for the refrigerant to enter the plate heat exchanger is via the liquid line.

[0085] Specifically, the refrigerant enters pipe II of the three-pipe receiver from the liquid line of the plate heat exchanger. Pipe II extends to the bottom of the receiver, ensuring that the refrigerant enters in liquid form. Within the receiver, the refrigerant undergoes gas-liquid separation. The liquid refrigerant flows out from pipe I at the bottom of the receiver, while the gaseous refrigerant is temporarily stored at the top. The saturated liquid refrigerant flowing out from pipe I then enters the electronic expansion valve for precise throttling, forming a low-temperature, low-pressure two-phase refrigerant, which then enters the plate heat exchanger for evaporation and heat absorption (cooling mode) or condensation and heat release (heating mode). This pathway ensures that the refrigerant entering the plate heat exchanger is pure liquid, facilitating uniform distribution within the heat exchanger's channels and improving heat exchange efficiency. Simultaneously, the receiver also plays a role in balancing the amount of circulating refrigerant in the system, ensuring efficient and stable operation under steady-state conditions.

[0086] Therefore, this specific implementation method, by precisely controlling the closing timing of the solenoid valve and the refrigerant flow path, quickly switches the refrigerant circulation to the main circuit after the system returns to steady state, ensuring that the plate heat exchanger can obtain sufficient and evenly distributed liquid refrigerant for efficient heat exchange. This significantly improves the heat exchange efficiency and operational stability of the system while eliminating the risk of freezing.

[0087] In this embodiment, when the system is operating in cooling mode and has entered a steady-state operating state, the control solenoid valve remains closed. Specifically, the system determines whether it has entered a stable cooling operating state by detecting whether the difference between the low-pressure saturation temperature and the outlet water temperature is less than a preset constant A, where A is a preset constant related to the heat exchange efficiency of the plate heat exchanger; the higher the heat exchange efficiency, the smaller the value of A. When it is determined that the system has entered a stable cooling operating state, the solenoid valve is closed, and at this time, the refrigerant flow path in the three-pipe receiver changes.

[0088] Specifically, pipe I of the receiver is connected to the electronic expansion valve, pipe II extends to the bottom of the receiver and connects to the liquid pipe of the plate heat exchanger, and pipe III is located at the top of the receiver and connects to the gas pipe of the plate heat exchanger via a solenoid valve. When the solenoid valve is closed, the passage of pipe III is blocked, and the liquid refrigerant in the receiver can only flow out through pipe II and enter the interior of the plate heat exchanger via the liquid pipe, where it is then distributed to each heat exchange channel for evaporation and heat absorption. During this process, because the solenoid valve is closed, the refrigerant cannot bypass directly to the compressor suction side through pipe III, thus ensuring that all liquid refrigerant enters the plate heat exchanger to participate in heat exchange. At the same time, the three-pipe receiver also plays a role in balancing the refrigerant circulation volume of the system under stable refrigeration operation.

[0089] Specifically, in cooling mode, the system requires less refrigerant circulation than in heating mode. The receiver stores excess liquid refrigerant within its internal space, automatically adjusting the refrigerant level when switching between cooling and heating modes to prevent performance degradation or instability due to refrigerant mismatch. Furthermore, with the solenoid valve closed, the two-phase refrigerant flowing from the throttling device undergoes gas-liquid separation in the receiver, ensuring that the refrigerant entering the plate heat exchanger from tube II is saturated liquid. Compared to two-phase refrigerant, pure liquid refrigerant is more evenly distributed in the channels of the plate heat exchanger, significantly improving heat exchange efficiency.

[0090] Therefore, this specific implementation method, by keeping the solenoid valve closed, allows the liquid refrigerant in the three-pipe receiver to enter the plate heat exchanger from pipe II for evaporation and heat absorption. At the same time, it utilizes the receiver to balance the differences in refrigerant circulation volume in different modes of the system, thereby improving the uniformity of refrigerant distribution and heat exchange efficiency under stable refrigeration operation, and enhancing the stability of system operation.

[0091] In this embodiment, a complete implementation of an antifreeze control method for an air-cooled chilled water heat pump system will be described in detail, including the control logic, parameter configuration, and refrigerant flow path under various unsteady operating states.

[0092] Specifically, when the system starts cooling, the four-way valve slider is located on the cooling side. At this time, the solenoid valve opens, and the refrigerant in the receiver flows to the compressor simultaneously from pipes II and III. That is, the refrigerant flows from pipe II through the plate heat exchanger and returns to the compressor, while it also flows directly back to the compressor from pipe III. This alleviates the sudden drop in low pressure caused by the lag in refrigerant flow due to the sudden start of the compressor, and avoids the refrigerant side temperature of the plate heat exchanger being too low, which could cause the water side to freeze and expand, damaging the plate heat exchanger structure.

[0093] Specifically, when the compressor operating frequency is detected to be greater than zero, the solenoid valve is opened. Then, the difference between the low-pressure saturation temperature and the outlet water temperature is calculated in real time. When this difference is less than a preset constant A, the system is determined to have returned to steady-state operation, and the solenoid valve is closed. The preset constant A is positively correlated with the heat exchange efficiency of the plate heat exchanger; the higher the heat exchange efficiency, the smaller the value of A. After the solenoid valve closes, the liquid refrigerant in the receiver enters the plate heat exchanger from pipe II and is distributed to each channel for evaporation and heat absorption, and the system enters stable refrigeration operation.

[0094] Before heating starts and the four-way valve switches, the four-way valve slider is still in the cooling side. At this time, the solenoid valve is open, and refrigerant flows from the compressor discharge port through the four-way valve. Part of the refrigerant enters the liquid receiver III pipe through the plate heat exchanger gas pipe, and the other part enters the liquid receiver II pipe through the plate heat exchanger liquid pipe. The two refrigerant streams mix in the liquid receiver and then flow out from the liquid receiver I pipe to the electronic expansion valve, thereby reducing the amount of low-temperature refrigerant entering the plate heat exchanger. When the four-way valve switches to the heating side, the plate heat exchanger becomes a condenser. At this time, the corresponding saturation temperature is detected by the high-pressure sensor. When the saturation temperature is greater than the preset constant B, it is determined that the system has returned to a steady-state operating state, and the solenoid valve is closed. The preset constant B is negatively correlated with the thickness of the heat exchanger plates. The thicker the plates, the lower the risk of freezing, and the smaller the value of B. After the solenoid valve is closed, the refrigerant flows from the compressor discharge port through the four-way valve, then through the liquid pipe of the plate heat exchanger into the receiver II pipe, flows out from the receiver I pipe to the electronic expansion valve, and then enters the plate heat exchanger for condensation and heat release after throttling.

[0095] When the heating system meets the defrosting conditions and is ready to enter defrosting mode, the four-way valve switches from the heating side to the cooling side, and the plate heat exchanger changes from a condenser to an evaporator. The refrigerant flow direction changes, and the refrigerant pressure inside the plate heat exchanger drops instantly to the low pressure before defrosting, or even lower, posing a significant risk of freezing. At this time, the control solenoid valve opens, and the refrigerant in the receiver flows simultaneously from pipes II and III to the compressor, mitigating the sudden pressure drop caused by the refrigerant flow lag due to the abrupt switching of the four-way valve, and preventing a large amount of low-temperature refrigerant from entering the plate heat exchanger. When the low-pressure saturation temperature is detected to be greater than the preset constant B, or when the four-way valve switches back from the cooling side to the heating side, it is determined that the system has returned to a steady-state operating state, and the solenoid valve closes. During the defrosting process, if the electronic expansion valve is closed, the receiver acts as a vapor-liquid separator, with refrigerant flowing in from pipe I and out from pipe II. Pure liquid refrigerant entering the plate heat exchanger facilitates distribution and heat exchange.

[0096] Under stable refrigeration operation, when the water flow suddenly decreases, the system's cooling capacity remains unchanged, but the reduced hot water volume causes a sudden drop in water temperature. Furthermore, insufficient heat absorption leads to a decrease in low-pressure, posing a risk of freezing. In this situation, if the flow switch is detected to be open, or the low-pressure saturation temperature is less than or equal to a preset constant C, the system is determined to be in an unsteady-state operation with abnormal water flow. The solenoid valve is then opened, allowing refrigerant to bypass the flow path and reduce the amount of refrigerant entering the plate heat exchanger. If the preset constant C is greater than the low-pressure protection value but less than the preset constant B, the system is in a sub-healthy refrigeration operation state. When the flow switch changes from open to open, and the low-pressure saturation temperature is greater than the preset constant B, the system is determined to have returned to a steady-state operation, and the solenoid valve is closed. If the compressor operating frequency drops to zero, it is directly determined to be in a steady-state operation, and the solenoid valve is closed to prevent refrigerant migration due to natural temperature differences.

[0097] Under stable refrigeration operation, the solenoid valve remains closed. The liquid refrigerant in the three-pipe receiver enters the plate heat exchanger from pipe II and is distributed to each channel for evaporation and heat absorption. At the same time, the receiver balances the difference in refrigerant circulation between the refrigeration and heating modes of the system, ensuring that the liquid entering the liquid pipe of the plate heat exchanger is saturated liquid refrigerant. Compared with the two-phase state after throttling, the pure liquid is more evenly distributed in the plate heat exchanger, resulting in higher heat exchange efficiency.

[0098] Therefore, this embodiment uses the above control method to suppress the risk of water-side freezing of the plate heat exchanger during non-steady-state operation, improve system reliability, and improve the uniformity of refrigerant distribution, thereby improving heat exchange efficiency.

[0099] Corresponding to the above method embodiments, this application also provides an electronic device, which includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus.

[0100] Memory, used to store computer programs; When the processor executes a program stored in the memory, it implements the control method of the air-cooled chilled water heat pump system as described in any of the second aspect embodiments above.

[0101] The communication bus mentioned in the above electronic devices can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into address bus, data bus, control bus, etc. For ease of illustration, only one thick line is used to represent it in the diagram, but this does not indicate that there is only one bus or one type of bus.

[0102] The communication interface is used for communication between the aforementioned photovoltaic air conditioner and other devices.

[0103] The memory may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory may also be at least one storage device located remotely from the aforementioned processor.

[0104] The processors mentioned above can be general-purpose processors, including central processing units (CPUs), network processors (NPs), etc.; they can also be digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0105] In another embodiment provided in this application, a storage medium is also provided, which stores instructions that, when run on a computer, cause the computer to execute the control method of any of the air-cooled chilled water heat pump systems described in the above embodiments.

[0106] In another embodiment provided in this application, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to execute the control method of any of the air-cooled chilled water heat pump systems described in the above embodiments.

[0107] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a storage medium or transmitted from one storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid state disk (SSD)).

[0108] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0109] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0110] The above description is merely a preferred embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application are included within the scope of protection of this application.

Claims

1. An air-cooled chilled water heat pump system, characterized in that, include: Compressor, four-way valve, vapor-liquid separator, finned heat exchanger, electronic expansion valve, plate heat exchanger, three-pipe liquid receiver, and solenoid valve; among which, The solenoid valves are connected to the gas pipe of the plate heat exchanger and the three-pipe liquid reservoir, respectively. The three-pipe liquid reservoir is also connected to the liquid pipe of the plate heat exchanger and the electronic expansion valve, respectively. When the system is in heating mode, the solenoid valve is closed, and the three-pipe liquid receiver is used to balance the difference in refrigerant circulation in the system. When the system is in a stable cooling state, the solenoid valve is closed, and the three-pipe liquid receiver is used to ensure that the liquid entering the liquid pipe is saturated liquid refrigerant; When the system is in cooling start-up, heating conversion defrosting operation, or cooling abnormal state, the solenoid valve opens, connecting the bypass flow path to reduce the refrigerant flow of the plate heat exchanger.

2. The air-cooled chilled water heat pump system according to claim 1, characterized in that, The compressor is connected to port D of the four-way valve and the vapor-liquid separator, respectively. The C port, S port, and E port of the four-way valve are respectively connected to the plate heat exchanger, the vapor-liquid separator, and the finned heat exchanger. The finned heat exchanger is connected to the three-pipe liquid reservoir via the electronic expansion valve.

3. The air-cooled chilled water heat pump system according to claim 1, characterized in that, The three-pipe liquid reservoir includes pipe I, pipe II, and pipe III; wherein... The first ends of tube I and tube II are both located at the bottom of the three-pipe reservoir, and the first end of tube III is located at the top of the three-pipe reservoir; The second end of tube I is connected to the electronic expansion valve, the second end of tube II is connected to the plate heat exchanger, and the second end of tube III is connected to the solenoid valve.

4. The air-cooled chilled water heat pump system according to claim 3, characterized in that, When the system is in cooling mode, ports D and E of the four-way valve are connected, and ports C and S of the four-way valve are connected. When the system is in heating mode, the D port and C port of the four-way valve are connected, and the E port and S port of the four-way valve are connected.

5. A control method for an air-cooled chilled water heat pump system, characterized in that, The air-cooled chilled water heat pump system is the air-cooled chilled water heat pump system as described in any one of claims 1 to 4, and the method includes: The detection system is checked to see if it is in a non-steady-state operating state, wherein the non-steady-state operating state includes cooling start-up, heating start-up with four-way valve reversal, defrosting switching, and abnormal water flow. When the unsteady operating state is detected, the solenoid valve is opened to allow the refrigerant to pass through the bypass path to reduce the amount of refrigerant entering the plate heat exchanger. The detection system is checked to see if it has returned to a steady-state operating state, wherein the steady-state operating state includes the low-pressure saturation temperature reaching a safe range and the water flow returning to normal; When the steady-state operation is detected, the solenoid valve is closed to allow the refrigerant to enter the plate heat exchanger normally for heat exchange.

6. The method according to claim 5, characterized in that, Whether the detection system is in a non-steady-state operating state includes: Check if the compressor's operating frequency is greater than zero and the four-way valve is on the refrigeration side. If these conditions are met, it is determined to be in refrigeration start-up state. The compressor's operating frequency is checked to see if it is greater than zero and if the four-way valve has switched from the cooling side to the heating side. If these conditions are met, the system is determined to be in heating mode and the four-way valve is in reversing mode. When the system is in heating mode and defrosting conditions are met, check whether the four-way valve switches from the heating side to the cooling side. If it does, it is determined to be in defrosting switching mode. When the system is in cooling mode, check whether the water flow switch is open or whether the low-pressure saturation temperature is less than or equal to the preset constant C. If the conditions are met, it is determined that the water flow is abnormal.

7. The method according to claim 5, characterized in that, Whether the detection system has returned to a steady-state operating state includes: Once the compressor operates at a frequency greater than zero and the solenoid valve is open, the difference between the low-pressure saturation temperature and the outlet water temperature is calculated in real time. If the difference is less than a preset constant A, it is determined that the system has recovered to the steady-state operation state after the cooling start-up, wherein the preset constant A is positively correlated with the heat exchange efficiency of the plate heat exchanger.

8. The method according to claim 5, characterized in that, Whether the detection system has returned to a steady-state operating state also includes: After the four-way valve is switched to the heating side and the solenoid valve is opened, the saturation temperature corresponding to the high-pressure sensor is detected in real time. If the saturation temperature is greater than the preset constant B, it is determined that the system has recovered to the steady-state operation state after the heating start-up and the four-way valve switching. The preset constant B is negatively correlated with the thickness of the heat exchanger plates of the plate heat exchanger.

9. The method according to claim 8, characterized in that, Whether the detection system has returned to a steady-state operating state also includes: When the system is in defrost mode, the low-pressure saturation temperature is monitored in real time. If the low-pressure saturation temperature is greater than the preset constant B, or the four-way valve switches from the cooling side back to the heating side, then it is determined that the system has returned to the steady-state operation state after the defrosting switch or exited the defrosting mode.

10. The method according to claim 8, characterized in that, Whether the detection system has returned to a steady-state operating state also includes: When the flow switch changes from open to closed and the low-pressure saturation temperature is greater than the preset constant B, it is determined that the system has recovered to the steady-state operation state after the abnormal recovery of water flow. If the compressor operating frequency drops to zero, the system is determined to be in a shutdown state and the solenoid valve is closed.

11. The method according to claim 5, characterized in that, Also includes: When the system is in a stable cooling operation state, keep the solenoid valve closed so that the liquid refrigerant in the three-pipe liquid receiver enters the plate heat exchanger from pipe II and is distributed to each channel for evaporation and heat absorption. The difference in refrigerant circulation between the cooling and heating modes of the system is balanced by the liquid receiver.

12. An electronic device, characterized in that, It includes a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other through the communication bus; Memory, used to store computer programs; The processor, when executing a program stored in memory, implements the control method of the air-cooled chilled water heat pump system according to any one of claims 5-11.

13. A storage medium having a computer program stored thereon, characterized in that, When executed by the processor, the program implements the control method for the air-cooled chilled water heat pump system as described in any one of claims 5-11.

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