A freeze-proof system and method for a heat pump unit and a heat pump unit

Abstract

The application provides a freeze-proof system and method of a heat pump unit and the heat pump unit. The freeze-proof device is arranged on a pipeline connected with a plate heat exchanger and a fin heat exchanger, and whether the refrigerant flows through the freeze-proof device for preheating is controlled according to the temperature of the liquid refrigerant in the liquid refrigerant pipeline of the plate heat exchanger, so that the temperature of the liquid refrigerant entering the plate heat exchanger in the defrosting mode is improved, the plate heat exchanger is prevented from being frozen and cracked, and the safety of system operation is improved.

Description

Technical Field

[0001] This invention relates to the field of energy and environmental technology, specifically to an anti-freezing and cracking system, anti-freezing method, and heat pump unit for a heat pump unit. Background Technology

[0002] In air-source heat pump units, plate heat exchangers have gradually become the mainstream water-side heat exchanger due to their advantages such as high heat exchange efficiency, small size, light weight, and low cost. However, when using plate heat exchangers and air-source heat pump units under harsh defrosting conditions, their low evaporation pressure makes them extremely prone to ice blockage when the water flow is low and the water temperature is low. This forces the plate heat exchanger to crack, leading to serious unit reliability issues. This problem severely limits the widespread use of plate heat exchangers in air-source heat pump units and is extremely detrimental to the further development of heat pump units. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a freeze-proof crack prevention system, freeze-proof method and heat pump unit to solve the problem that plate heat exchangers are easily cracked during defrosting operation of heat pump units in related technologies.

[0004] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0005] According to a first aspect of the present invention, a freeze-cracking prevention system for a heat pump unit is provided, the heat pump unit comprising a plate heat exchanger and a finned heat exchanger, the freeze-cracking prevention system comprising:

[0006] An antifreeze device is installed on the pipeline connecting the plate heat exchanger and the finned heat exchanger.

[0007] A liquid refrigerant temperature sensor is installed on the liquid refrigerant pipeline of the plate heat exchanger to detect the temperature of the flowing liquid refrigerant.

[0008] The controller is used to control whether the refrigerant flows through the antifreeze device for preheating based on the temperature of the liquid refrigerant, so as to increase the temperature of the liquid refrigerant entering the plate heat exchanger in defrosting mode.

[0009] Preferably, the antifreeze device includes:

[0010] A liquid receiver for storing liquid refrigerant includes a tank body and a first and second pipe port inserted parallel to the tank body. The first pipe port is connected to the liquid refrigerant pipeline of the plate heat exchanger, and the second pipe port is connected to the finned heat exchanger through an electric three-way valve.

[0011] The electric three-way valve is connected to the controller and also to the liquid refrigerant pipeline of the plate heat exchanger.

[0012] Preferably, the first pipe opening is a sleeve with an open bottom, and the inner tube of the sleeve is connected to the liquid refrigerant pipeline of the plate heat exchanger;

[0013] The distance between the bottom of the first pipe opening and the bottom of the tank is less than the distance between the bottom of the second pipe opening and the bottom of the tank.

[0014] Preferably, the system further includes:

[0015] An electronic expansion valve, connected to the controller, is installed on the pipeline connecting the antifreeze device and the finned heat exchanger.

[0016] According to a second aspect of the present invention, a method for preventing freezing of a heat pump unit is provided, comprising:

[0017] Detect the temperature of the liquid refrigerant in the liquid refrigerant pipeline flowing through the plate heat exchanger;

[0018] Based on the temperature of the liquid refrigerant, control whether the refrigerant flows through the antifreeze device for preheating, so as to increase the temperature of the liquid refrigerant entering the plate heat exchanger in defrosting mode.

[0019] Preferably, the step of controlling whether the refrigerant flows through the antifreeze device for preheating based on the liquid refrigerant temperature to increase the temperature of the liquid refrigerant entering the plate heat exchanger in defrost mode includes:

[0020] If the temperature of the liquid refrigerant is lower than the preset temperature, the refrigerant is controlled to flow through the antifreeze device for preheating, and the preheated refrigerant then flows into the plate heat exchanger.

[0021] If the temperature of the liquid refrigerant is greater than or equal to the preset temperature, the refrigerant is controlled to flow directly into the plate heat exchanger without being preheated by the antifreeze device.

[0022] Preferably, if the antifreeze device includes an electric three-way valve and a liquid receiver, the control of the refrigerant flow through the antifreeze device for preheating specifically involves:

[0023] The electric three-way valve is controlled to disconnect the liquid refrigerant pipeline from the plate heat exchanger, and the electric three-way valve is controlled to connect to the liquid receiver so that the refrigerant flows through the antifreeze device for preheating.

[0024] The control of the refrigerant from flowing through the antifreeze device for preheating specifically involves:

[0025] The electric three-way valve is connected to the liquid refrigerant pipeline of the plate heat exchanger, and the electric three-way valve is disconnected from the liquid receiver so that the refrigerant does not flow through the antifreeze device for preheating.

[0026] Preferably, the method further includes:

[0027] In heating mode, the refrigerant is controlled to flow through the antifreeze device for storage, so that in cooling mode the refrigerant can be drawn from the receiver through pressure difference and added to the refrigeration cycle.

[0028] In cooling mode, the refrigerant is prevented from flowing through the antifreeze device.

[0029] According to a third aspect of the present invention, a heat pump unit is provided, comprising:

[0030] The above-mentioned heat pump unit has an anti-freeze cracking system.

[0031] Preferably, the heat pump unit is an air source heat pump unit.

[0032] The technical solutions provided by the embodiments of the present invention may include the following beneficial effects:

[0033] By installing an antifreeze device on the pipeline connecting the plate heat exchanger and the finned heat exchanger, and controlling whether the refrigerant flows through the antifreeze device for preheating based on the temperature of the liquid refrigerant in the liquid refrigerant pipeline of the plate heat exchanger, the temperature of the liquid refrigerant entering the plate heat exchanger in defrosting mode is increased, preventing the plate heat exchanger from freezing and cracking, and improving the safety of system operation. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of an anti-freeze cracking system for a heat pump unit according to an exemplary embodiment;

[0035] Figure 2 This is a schematic diagram of the structure of a sleeve according to another exemplary embodiment;

[0036] Figure 3 This is a flowchart illustrating an antifreeze method for a heat pump unit according to another exemplary embodiment;

[0037] Figure 4 This is a schematic diagram of the structure of an electronic three-way valve according to another exemplary embodiment. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0039] Example 1

[0040] Figure 1This is a schematic diagram illustrating the structure of an anti-freeze cracking system for a heat pump unit according to an exemplary embodiment, such as... Figure 1 As shown, the heat pump unit includes a plate heat exchanger 1 and a finned heat exchanger 2, and the anti-freeze cracking system includes:

[0041] Antifreeze device 3 is installed on the pipeline connecting the plate heat exchanger 1 and the finned heat exchanger 2;

[0042] A liquid refrigerant temperature sensor 4 is installed on the liquid refrigerant pipeline 5 of the plate heat exchanger 1 to detect the temperature of the liquid refrigerant flowing through it.

[0043] The controller is used to control whether the refrigerant flows through the antifreeze device 3 for preheating based on the temperature of the liquid refrigerant, so as to increase the temperature of the liquid refrigerant entering the plate heat exchanger 1 in defrosting mode.

[0044] It is understood that the technical solution provided in this embodiment, by setting an antifreeze device 3 on the pipeline connecting the plate heat exchanger 1 and the finned heat exchanger 2, and controlling whether the refrigerant flows through the antifreeze device 3 for preheating according to the temperature of the liquid refrigerant in the liquid refrigerant pipeline 5 of the plate heat exchanger 1, increases the temperature of the liquid refrigerant entering the plate heat exchanger 1 in the defrosting mode, avoids the plate heat exchanger 1 from freezing and cracking, and improves the safety of system operation.

[0045] In practice, the antifreeze device 3 includes:

[0046] The liquid receiver 31 is used to store liquid refrigerant, including a tank 311 and a first port 312 and a second port 313 inserted parallel to each other in the tank 311. The first port 312 is connected to the liquid refrigerant pipeline 5 of the plate heat exchanger 1, and the second port 313 is connected to the finned heat exchanger 2 through an electric three-way valve 32.

[0047] The electric three-way valve 32 is connected to the controller and also to the liquid refrigerant pipeline 5 of the plate heat exchanger 1.

[0048] It is understood that the technical solution provided in this embodiment stores high-temperature refrigerant in the liquid receiver 31. The low-temperature refrigerant flowing into the liquid receiver 31 from the finned heat exchanger 2 can mix with the high-temperature refrigerant and then flow into the liquid refrigerant pipeline 5 of the plate heat exchanger 1 from the second pipe port 313, thereby preventing the plate heat exchanger 1 from freezing and cracking. The three-way valve can control whether the refrigerant passes through the liquid receiver 31, so that the distribution of the refrigerant is kept balanced and the flexibility of the system is improved.

[0049] In practice, the first pipe opening 312 is a sleeve 314 with an open bottom, and the inner tube of the sleeve 314 is connected to the liquid refrigerant pipeline 5 of the plate heat exchanger 1.

[0050] The distance between the bottom of the first port 312 and the bottom of the tank 311 is less than the distance between the bottom of the second port 313 and the bottom of the tank 311.

[0051] like Figure 2 As shown, the first pipe opening 312 is set as a sleeve 314 with a bottom opening, and the distance between the bottom of the first pipe opening 312 and the bottom of the tank 311 is smaller than the distance between the bottom of the second pipe opening 313 and the bottom of the tank 311. This divides the refrigerant in the storage tank into two areas: the inner tube of the sleeve 314 is the liquid outlet area, and the outer tube of the sleeve 314 is the refrigerant mixing area. The sleeve 314 is designed to allow the high-temperature refrigerant and the low-temperature refrigerant to be fully mixed before flowing into the liquid outlet area, preventing the low-temperature refrigerant from flowing into the plate heat exchanger 1 and causing the plate heat exchanger 1 to freeze and crack. In addition, when the pressure in the liquid refrigerant pipeline 5 of the plate heat exchanger 1 is lower than the pressure in the liquid outlet area, the plate heat exchanger 1 can be quickly replenished with refrigerant, ensuring the stable operation of the system.

[0052] In practice, the system also includes:

[0053] An electronic expansion valve 6, connected to the controller, is installed on the pipeline connecting the antifreeze device 3 and the finned heat exchanger 2.

[0054] It is understood that the technical solution provided in this embodiment, by installing an electronic expansion valve 6 on the pipeline connecting the antifreeze device 3 and the finned heat exchanger 2, can control the flow of refrigerant through the opening degree of the electronic expansion valve 6, thereby ensuring the stable operation of the system.

[0055] Example 2

[0056] Figure 3 This is a flowchart illustrating an antifreeze method for a heat pump unit according to an exemplary embodiment, such as... Figure 3 As shown, the method includes:

[0057] Step S11: Detect the temperature of the liquid refrigerant in the liquid refrigerant pipeline 5 flowing through the plate heat exchanger 1;

[0058] Step S12: Based on the temperature of the liquid refrigerant, control whether the refrigerant flows through the antifreeze device 3 for preheating, so as to increase the temperature of the liquid refrigerant entering the plate heat exchanger 1 in defrosting mode.

[0059] It is understood that the technical solution provided in this embodiment controls whether the refrigerant flows through the antifreeze device 3 for preheating according to the temperature of the liquid refrigerant, which can increase the temperature of the liquid refrigerant entering the plate heat exchanger 1 in the defrosting mode, prevent the plate heat exchanger 1 from freezing and cracking, and ensure the stable operation of the system.

[0060] In practice, controlling whether the refrigerant flows through the antifreeze device 3 for preheating based on the liquid refrigerant temperature to increase the temperature of the liquid refrigerant entering the plate heat exchanger 1 in defrost mode includes:

[0061] If the temperature of the liquid refrigerant is lower than the preset temperature, the refrigerant is controlled to flow through the antifreeze device 3 for preheating, and the preheated refrigerant then flows into the plate heat exchanger 1.

[0062] If the temperature of the liquid refrigerant is greater than or equal to the preset temperature, the refrigerant is controlled not to flow through the antifreeze device 3 for preheating, but directly flows into the plate heat exchanger 1.

[0063] It should be noted that the preset temperature is an empirical value or set according to actual working requirements. For example, if the preset temperature is set to 5°C, and the temperature of the liquid refrigerant is less than 5°C, it means that the temperature of the liquid refrigerant is too low. In this case, the refrigerant is controlled to flow through the antifreeze device 3 for preheating to prevent the plate heat exchanger 1 from freezing and cracking. If the temperature of the liquid refrigerant is greater than or equal to 5°C, the refrigerant is controlled not to flow through the antifreeze device 3 for preheating, but to flow directly into the plate heat exchanger 1. This prevents the refrigerant in the liquid reservoir 31 from overflowing and ensures the refrigerant flow rate in the entire system, so that the system can operate stably.

[0064] In practical application, if the antifreeze device 3 includes an electric three-way valve 32 and a liquid reservoir 31, the control of the refrigerant flow through the antifreeze device 3 for preheating is specifically as follows:

[0065] Control the electric three-way valve 32 to disconnect the connection with the liquid refrigerant pipeline 5 of the plate heat exchanger 1, and control the electric three-way valve 32 to connect with the liquid receiver 31 so that the refrigerant flows through the antifreeze device 3 for preheating;

[0066] The control of the refrigerant from flowing through the antifreeze device 3 for preheating is specifically as follows:

[0067] The electric three-way valve 32 is connected to the liquid refrigerant pipeline 5 of the plate heat exchanger 1, and the electric three-way valve 32 is disconnected from the liquid reservoir 31 so that the refrigerant does not flow through the antifreeze device 3 for preheating.

[0068] like Figure 4As shown, the electric three-way valve 32 has ports A and B. In the system defrost mode, if the electric three-way valve 32 is turned to port A, the refrigerant flows sequentially through the compressor discharge port 71, four-way valve 8, finned heat exchanger 2, electronic expansion valve 6, electronic three-way valve port A, liquid receiver 31, plate heat exchanger 1, four-way valve 8, gas-liquid separator 9, and compressor suction port 72. In the above flow path, the refrigerant will first flow through the liquid receiver 31, and the mixed and heated refrigerant will flow into the plate heat exchanger 1, preventing the plate heat exchanger 1 from freezing and cracking. If the electric three-way valve 32 is turned to port B, the refrigerant flows sequentially through the compressor discharge port 71, four-way valve 8, finned heat exchanger 2, electronic expansion valve 6, electronic three-way valve port B, plate heat exchanger 1, four-way valve 8, gas-liquid separator 9, and compressor suction port 72. In the above flow path, the refrigerant does not flow into the plate heat exchanger 1, and the refrigerant flows faster in the system, ensuring stable system operation.

[0069] In practice, the method also includes:

[0070] In heating mode, the refrigerant is controlled to flow through the antifreeze device 3 for storage, so that in cooling mode the refrigerant can be drawn out from the liquid receiver 31 through pressure difference and replenished into the refrigeration cycle.

[0071] In cooling mode, the refrigerant is prevented from flowing through the antifreeze device 3.

[0072] It should be noted that the system requires less refrigerant in heating mode compared to cooling mode. Therefore, in heating mode, the electronic three-way valve turns to port A, and the refrigerant flows sequentially through the compressor discharge port 71, four-way valve 8, plate heat exchanger 1, liquid receiver 31, electronic three-way valve port A, electronic expansion valve 6, finned heat exchanger 2, four-way valve 8, gas-liquid separator 9, and compressor suction port 72. The high-temperature, high-pressure refrigerant is stored in the liquid receiver 31 to raise the temperature of the low-temperature refrigerant. After switching from heating mode to cooling mode, the electronic three-way valve turns... The refrigerant flows sequentially through the compressor exhaust port 71, four-way valve 8, finned heat exchanger 2, electronic expansion valve 6, electronic three-way valve port B, plate heat exchanger 1, four-way valve 8, gas-liquid separator 9, and compressor suction port 72. Since some refrigerant flows into the liquid receiver 31 in heating mode, the pressure in the liquid outlet area of ​​the liquid receiver 31 is greater than the pressure in the liquid refrigerant pipeline 5 of the plate heat exchanger 1. The pressure difference allows the refrigerant to be drawn out onto the liquid refrigerant pipeline 5, thereby achieving a reasonable distribution of refrigerant in heating and cooling modes.

[0073] Example 3

[0074] A heat pump unit according to another exemplary embodiment includes:

[0075] The above-mentioned heat pump unit has an anti-freeze cracking system.

[0076] In practice, the heat pump unit is an air source heat pump unit.

[0077] It is understood that the technical solution provided in this embodiment sets up the anti-freezing and cracking system in the air source heat pump unit. By setting up an anti-freezing device 3 on the pipeline connecting the plate heat exchanger 1 and the finned heat exchanger 2, and controlling whether the refrigerant flows through the anti-freezing device 3 for preheating according to the temperature of the liquid refrigerant in the liquid refrigerant pipeline 5 of the plate heat exchanger 1, the temperature of the liquid refrigerant entering the plate heat exchanger 1 in the defrosting mode is increased, avoiding the plate heat exchanger 1 from freezing and cracking, and improving the safety of system operation.

[0078] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0079] If the integrated units in the above embodiments are implemented as software functional units and sold or used as independent products, they can be stored in the aforementioned computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause one or more computer devices (which may be personal computers, servers, or network devices, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application.

[0080] In the above embodiments of this application, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0081] In the several embodiments provided in this application, it should be understood that the disclosed client can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces, indirect coupling or communication connection between units or modules, and may be electrical or other forms.

[0082] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0083] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0084] The above description is only a preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A freeze-cracking prevention system for a heat pump unit, the heat pump unit comprising a plate heat exchanger and a finned heat exchanger, characterized in that, The anti-freeze cracking system includes: An antifreeze device is installed on the pipeline connecting the plate heat exchanger and the finned heat exchanger. A liquid refrigerant temperature sensor is installed on the liquid refrigerant pipeline of the plate heat exchanger to detect the temperature of the flowing liquid refrigerant. The controller is used to control whether the refrigerant flows through the antifreeze device for preheating based on the temperature of the liquid refrigerant, so as to increase the temperature of the liquid refrigerant entering the plate heat exchanger in defrosting mode. A liquid receiver for storing liquid refrigerant includes a tank body and a first and second pipe port inserted parallel to the tank body. The first pipe port is connected to the liquid refrigerant pipeline of the plate heat exchanger, and the second pipe port is connected to the finned heat exchanger through an electric three-way valve. The electric three-way valve is connected to the controller and also to the liquid refrigerant pipeline of the plate heat exchanger; The first pipe opening is a sleeve with an open bottom, and the inner tube of the sleeve is connected to the liquid refrigerant pipeline of the plate heat exchanger. The distance between the bottom of the first pipe opening and the bottom of the tank is less than the distance between the bottom of the second pipe opening and the bottom of the tank.

2. The system according to claim 1, characterized in that, Also includes: An electronic expansion valve, connected to the controller, is installed on the pipeline connecting the antifreeze device and the finned heat exchanger.

3. A method for preventing freezing in a heat pump unit, characterized in that, The anti-freeze cracking system applicable to the heat pump unit according to any one of claims 1-2 comprises: Detect the temperature of the liquid refrigerant in the liquid refrigerant pipeline flowing through the plate heat exchanger; Based on the temperature of the liquid refrigerant, control whether the refrigerant flows through the antifreeze device for preheating, so as to increase the temperature of the liquid refrigerant entering the plate heat exchanger in defrosting mode.

4. The antifreeze method according to claim 3, characterized in that, The step of controlling whether the refrigerant flows through the antifreeze device for preheating based on the liquid refrigerant temperature, so as to increase the temperature of the liquid refrigerant entering the plate heat exchanger in defrost mode, includes: If the temperature of the liquid refrigerant is lower than the preset temperature, the refrigerant is controlled to flow through the antifreeze device for preheating, and the preheated refrigerant then flows into the plate heat exchanger. If the temperature of the liquid refrigerant is greater than or equal to the preset temperature, the refrigerant is controlled to flow directly into the plate heat exchanger without being preheated by the antifreeze device.

5. The method according to claim 4, characterized in that, If the antifreeze device includes an electric three-way valve and a liquid receiver, the control of the refrigerant flow through the antifreeze device for preheating is specifically as follows: The electric three-way valve is controlled to disconnect the liquid refrigerant pipeline from the plate heat exchanger, and the electric three-way valve is controlled to connect to the liquid receiver so that the refrigerant flows through the antifreeze device for preheating. The control of the refrigerant from flowing through the antifreeze device for preheating specifically involves: The electric three-way valve is connected to the liquid refrigerant pipeline of the plate heat exchanger, and the electric three-way valve is disconnected from the liquid receiver so that the refrigerant does not flow through the antifreeze device for preheating.

6. The method according to any one of claims 3 to 5, characterized in that, Also includes: In heating mode, the refrigerant is controlled to flow through the antifreeze device for storage, so that in cooling mode the refrigerant can be drawn from the receiver through pressure difference and added to the refrigeration cycle. In cooling mode, the refrigerant is prevented from flowing through the antifreeze device.

7. A heat pump unit, characterized in that, include: The anti-freezing cracking system for the heat pump unit according to any one of claims 1 to 2.

8. The heat pump unit according to claim 7, characterized in that, The heat pump unit is an air source heat pump unit.

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