A heat pump system for preventing freezing of a plate heat exchanger

Abstract

This invention relates to a heat pump system for preventing plate heat exchangers from freezing, which controls an ultrasonic device by: acquiring the operating mode of the heat pump system; and if the heat pump system is in defrost mode, acquiring the outlet water temperature T of the plate heat exchanger. out If the outlet water temperature T out If the water temperature is below the first outlet water temperature threshold, the ultrasonic device is activated; if the outlet water temperature T out If the evaporation temperature T is greater than or equal to the first outlet water temperature threshold, then obtain the evaporation temperature T. z And based on the outlet water temperature T out The range determines the evaporation temperature threshold T. z‑set Determine the evaporation temperature T z Is it less than the evaporation temperature threshold T? z‑set If yes, the ultrasonic device is activated. This invention, by installing an ultrasonic device on the plate heat exchanger, prevents localized icing caused by low-temperature refrigerant during defrosting, thereby improving the operational stability and service life of the heat pump system.

Description

Technical Field

[0001] This invention relates to the field of air source heat pump technology, and in particular to a heat pump system for preventing plate heat exchangers from freezing. Background Technology

[0002] An air source heat pump is a highly efficient and energy-saving device that utilizes low-grade heat energy from the air and is driven by a small amount of electricity to transfer heat from a low-temperature environment to a high-temperature environment. It mainly consists of a compressor, a four-way valve, a plate heat exchanger (condenser), a throttling component, and an outdoor heat exchanger (evaporator), all connected in sequence by refrigerant circulation pipes.

[0003] When operating in low-temperature environments, water vapor in the air condenses into frost when it encounters the cold surface of the outdoor heat exchanger. If defrosting is not performed in time, the frost layer will gradually thicken, affecting the normal operation of the heat pump system. Therefore, the heat pump system needs to switch a four-way valve to allow the high-temperature, high-pressure refrigerant to flow through the outdoor heat exchanger for defrosting.

[0004] However, the refrigerant temperature will drop significantly after defrosting, possibly even below freezing. When this low-temperature refrigerant enters the plate heat exchanger, its slow flow velocity may prevent sufficient heat exchange with the circulating water, leading to localized freezing of the circulating water within the plate heat exchanger. This situation can cause the plate heat exchanger to freeze through, allowing circulating water to enter the refrigerant piping, ultimately resulting in compressor damage and unit failure.

[0005] Currently, there is a lack of effective methods to solve the problem of localized icing caused by low-temperature refrigerant during the defrosting process of plate heat exchangers. Therefore, there is an urgent need for a heat pump system that can monitor and prevent plate heat exchangers from freezing in real time. Summary of the Invention

[0006] Based on this, the purpose of the present invention is to overcome the defects or deficiencies of the prior art and provide a heat pump system that prevents plate heat exchangers from freezing.

[0007] A heat pump system for preventing plate heat exchangers from freezing includes a compressor, a four-way valve, a plate heat exchanger, a throttling assembly, and an outdoor heat exchanger connected in sequence by refrigerant circulation pipes; an ultrasonic device fixedly mounted on an end plate of the plate heat exchanger; a temperature sensor mounted on the outlet pipe of the plate heat exchanger; a pressure sensor mounted on the return pipe of the compressor; and a controller electrically or communicatively connected to the four-way valve, temperature sensor, pressure sensor, and ultrasonic device, wherein the controller controls the ultrasonic device in the following manner:

[0008] Obtain the operating mode of the heat pump system. If the heat pump system is in defrost mode, obtain the outlet water temperature T of the plate heat exchanger. out If the outlet water temperature T out Less than the first outlet water temperature threshold Then activate the ultrasonic device; if the outlet water temperature T out Greater than or equal to the first outlet water temperature threshold Then obtain the evaporation temperature T z And based on the outlet water temperature T out The range determines the evaporation temperature threshold T. z-set Determine the evaporation temperature T z Is it less than the evaporation temperature threshold T? z-set If yes, then the ultrasound device will be activated.

[0009] Compared to existing technologies, the heat pump system for preventing plate heat exchangers from freezing described in this invention assesses the risk of freezing by detecting the outlet water temperature and evaporation temperature of the plate heat exchanger during the defrosting process of the outdoor heat exchanger, and uses an ultrasonic device to suppress the freezing of the plate heat exchanger.

[0010] In one embodiment, based on the outlet water temperature T out The range determines the evaporation temperature threshold T. z-set ,include:

[0011] Determine the outlet water temperature T out Is it greater than or equal to the second outlet water temperature threshold?

[0012] If so, then the evaporation temperature threshold T z-set The first evaporation temperature threshold

[0013] If not, then the evaporation temperature threshold T z-set The second evaporation temperature threshold

[0014] In one embodiment, the first outlet water temperature threshold Less than the second outlet water temperature threshold First evaporation temperature threshold Less than the second evaporation temperature threshold

[0015] In one embodiment, based on the outlet water temperature T out and evaporation temperature T z Determine the operating status of the ultrasonic device, including:

[0016] If the outlet water temperature T out <First outlet water temperature threshold Control the ultrasonic device to operate in its first working state;

[0017] If the second outlet water temperature threshold >Outlet water temperature T out ≥ First outlet water temperature threshold And the evaporation temperature T z <Evaporation temperature threshold Tz-set Control the ultrasonic device to operate in the second working state;

[0018] If the outlet water temperature T out ≥Second outlet water temperature threshold And the evaporation temperature T z <Evaporation temperature threshold T z-set The ultrasonic device is controlled to operate in the third working state.

[0019] In one embodiment, the ultrasonic device includes a shear wave transducer fixedly mounted on one end plate of the plate heat exchanger for outputting shear waves, a longitudinal wave transducer mounted on the other end plate of the plate heat exchanger for outputting longitudinal waves, a shear wave generator electrically connected to the shear wave transducer, and a longitudinal wave generator electrically connected to the longitudinal wave transducer.

[0020] In one embodiment, the first operating state is to control the transverse wave transducer to operate for M1 seconds, and then switch to the longitudinal wave transducer to operate for M2 seconds, with the two operating alternately.

[0021] The second working state is to control the transverse wave transducer to work for M3 seconds first, and then switch to the longitudinal wave transducer to work for M4 seconds, with the two working alternately.

[0022] The third working state is to control the transverse wave transducer to work for M5 seconds, and then switch to the longitudinal wave transducer to work for M6 seconds, with the two working alternately.

[0023] Among them, M1≥M2>M3≥M4>M5≥M6.

[0024] Furthermore, the present invention also provides a method for controlling an ultrasonic device to prevent a plate heat exchanger from freezing, wherein the ultrasonic device is fixedly mounted on the end plate of the plate heat exchanger, and includes the following control steps:

[0025] S10 obtains the operating mode of the heat pump system. If it is defrosting mode, then proceed to step S20.

[0026] S20 obtains the outlet water temperature T of the plate heat exchanger. out :

[0027] If the outlet water temperature T out Less than the first outlet water temperature threshold Then the ultrasound device will be activated;

[0028] If the outlet water temperature T out Greater than or equal to the first outlet water temperature threshold Then proceed to step S30;

[0029] S30 obtains the evaporation temperature T z And based on the outlet water temperature T out The range determines the evaporation temperature threshold T. z-setDetermine the evaporation temperature T z Is it less than the evaporation temperature threshold T? z-set :

[0030] If yes, then start the ultrasound device.

[0031] In one embodiment, the water temperature T in step S30 is... out The range determines the evaporation temperature threshold T. z-set ,include:

[0032] If the outlet water temperature T out ≥Second outlet water temperature threshold Then the evaporation temperature threshold T z-set The first evaporation temperature threshold

[0033]

[0034] If the second outlet water temperature threshold >Outlet water temperature T out ≥ First outlet water temperature threshold Then the evaporation temperature threshold T z-set The second evaporation temperature threshold

[0035] The first evaporation temperature threshold Less than the second evaporation temperature threshold

[0036] In one embodiment, the water temperature T in step S30 is... out The range determines the evaporation temperature threshold T. z-set ,include:

[0037] If the outlet water temperature T out ≥Second outlet water temperature threshold Then the evaporation temperature threshold T z-set The first evaporation temperature threshold

[0038]

[0039] If the second outlet water temperature threshold >Outlet water temperature T out ≥ First outlet water temperature threshold Then the evaporation temperature threshold T z-set The second evaporation temperature threshold

[0040] The first evaporation temperature threshold Less than the second evaporation temperature threshold

[0041] In one embodiment, based on the outlet water temperature T out and evaporation temperature Tz Determine the operating status of the ultrasonic device, including:

[0042] If the outlet water temperature T out <First outlet water temperature threshold Control the ultrasonic device to operate in its first working state;

[0043] If the second outlet water temperature threshold >Outlet water temperature T out ≥ First outlet water temperature threshold And the evaporation temperature T z <Evaporation temperature threshold T z-set Control the ultrasonic device to operate in the second working state;

[0044] If the outlet water temperature T out ≥Second outlet water temperature threshold And the evaporation temperature T z <Evaporation temperature threshold T z-set The ultrasonic device is controlled to operate in the third working state.

[0045] In one embodiment, the ultrasonic device includes a shear wave transducer fixedly mounted on one end plate of the plate heat exchanger for outputting shear waves, a longitudinal wave transducer mounted on the other end plate of the plate heat exchanger for outputting longitudinal waves, a shear wave generator electrically connected to the shear wave transducer, and a longitudinal wave generator electrically connected to the longitudinal wave transducer; a first operating state is to control the shear wave transducer to operate for M1 seconds, then switch to the longitudinal wave transducer to operate for M2 seconds, and the two alternate; a second operating state is to control the shear wave transducer to operate for M3 seconds, then switch to the longitudinal wave transducer to operate for M4 seconds, and the two alternate; a third operating state is to control the shear wave transducer to operate for M5 seconds, then switch to the longitudinal wave transducer to operate for M6 seconds, and the two alternate; wherein, M1≥M2>M3≥M4>M5≥M6.

[0046] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of a heat pump system structure for preventing plate heat exchangers from freezing, according to an embodiment of the present invention.

[0048] Figure 2 This is a schematic flowchart of the control method for the working state of the ultrasonic device according to an embodiment of the present invention. Detailed Implementation

[0049] The present invention will now be described in detail with reference to the accompanying drawings.

[0050] Please see Figure 1A heat pump system 10 for preventing plate heat exchangers from freezing according to the present invention includes a compressor 11, a four-way valve 12, a plate heat exchanger 13, a throttling assembly 14, and an outdoor heat exchanger 15 connected in one step by a refrigerant circulation pipe; wherein an ultrasonic device 16 is fixedly installed on the plate heat exchanger 13, the ultrasonic device 16 including an ultrasonic transducer 161 installed on both end plates of the plate heat exchanger 13, and an ultrasonic generator 162 electrically connected to the ultrasonic transducer 161.

[0051] Specifically, the ultrasonic transducer 161 includes a transverse wave transducer 161A disposed on one end plate of the plate heat exchanger 13 for outputting transverse waves, and a longitudinal wave transducer 161B disposed on the other end plate of the plate heat exchanger 13 for outputting longitudinal waves.

[0052] Specifically, the ultrasonic generator 162 includes a shear wave generator 162A electrically connected to the shear wave transducer 161, and a longitudinal wave generator 162B electrically connected to the longitudinal wave transducer 161.

[0053] The heat pump system 10 also includes a temperature sensor 17 installed on the outlet water pipe of the plate heat exchanger 13 and a pressure sensor 18 installed on the return gas pipe of the compressor 11. The temperature sensor 17 is used to detect the outlet water temperature T of the plate heat exchanger 13. out The pressure sensor 18 is used to detect the evaporation pressure P of the refrigerant. z The evaporation temperature T of the refrigerant was obtained by looking up a table. z .

[0054] The heat pump system 10 also includes a controller (not shown), which is electrically or communicatively connected to the four-way valve 12, temperature sensor 17, pressure sensor 18 and ultrasonic device 16.

[0055] Please see Figure 2 The controller in the heat pump system 10 of the present invention controls the ultrasonic device 16 by the following method:

[0056] S10 obtains the operating mode of the heat pump system:

[0057] If it is in defrost mode, proceed to step S20;

[0058] If it is another mode, continuously obtain the operating mode of the heat pump system.

[0059] S20 obtains the outlet water temperature T of the plate heat exchanger. out :

[0060] If the outlet water temperature T out Less than the first outlet water temperature threshold Then the ultrasound device will be activated;

[0061] If the outlet water temperature T out Greater than or equal to the first outlet water temperature threshold Then proceed to step S30.

[0062] S30 obtains the evaporation temperature T z And based on the outlet water temperature T out The range determines the evaporation temperature threshold T. z-set Determine the evaporation temperature T z Is it less than the evaporation temperature threshold T? z-set :

[0063] If yes, then start the ultrasound device;

[0064] If not, proceed to step S10.

[0065] Specifically, based on the outlet water temperature T out The range determines the evaporation temperature threshold T. z-set The method is as follows:

[0066] If the outlet water temperature T out ≥Second outlet water temperature threshold Then the evaporation temperature threshold T z-set The first evaporation temperature threshold

[0067]

[0068] If the second outlet water temperature threshold >Outlet water temperature T out ≥ First outlet water temperature threshold Then the evaporation temperature threshold T z-set The second evaporation temperature threshold

[0069] Specifically, the first outlet water temperature threshold The second outlet water temperature threshold is 15℃. The temperature is 30℃.

[0070] Specifically, the first evaporation temperature threshold Less than the second evaporation temperature threshold

[0071] Specifically, based on the outlet water temperature T out and evaporation temperature T z Determine the operating status of the ultrasonic device as follows:

[0072] If the outlet water temperature T out <First outlet water temperature threshold Control the ultrasonic device to operate in its first working state;

[0073] If the second outlet water temperature threshold >Outlet water temperature T out ≥ First outlet water temperature threshold And the evaporation temperature T z <Evaporation temperature threshold T z-set Control the ultrasonic device to operate in the second working state;

[0074] If the outlet water temperature T out ≥Second outlet water temperature threshold And the evaporation temperature T z <Evaporation temperature threshold T z-set The ultrasonic device is controlled to operate in the third working state.

[0075] Specifically, the first working state is to control the transverse wave transducer to work for M1 seconds, and then switch to the longitudinal wave transducer to work for M2 seconds, with the two working alternately.

[0076] The second working state is to control the transverse wave transducer to work for M3 seconds first, and then switch to the longitudinal wave transducer to work for M4 seconds, with the two working alternately.

[0077] The third working state is to control the transverse wave transducer to work for M5 seconds, and then switch to the longitudinal wave transducer to work for M6 seconds, with the two working alternately.

[0078] Among them, M1≥M2>M3≥M4>M5≥M6.

[0079] Specifically, M1 is 12, M2 is 10, M3 is 8, M4 is 6, M5 is 4, and M6 is 2.

[0080] In this invention, by installing an ultrasonic device on the plate heat exchanger, the cavitation and acoustic flow effects of ultrasound are utilized to enhance the turbulence of the refrigerant and circulating water, inhibit crystal nucleation growth, and prevent localized icing. In addition, the ultrasonic device can enhance the heat transfer effect, reduce flow dead zones, and improve the heat transfer coefficient of the plate heat exchanger, thereby improving the overall efficiency of the heat pump system.

[0081] Compared to existing technologies, the present invention provides a heat pump system for preventing plate heat exchangers from freezing. By installing an ultrasonic device on the plate heat exchanger and combining it with real-time monitoring by temperature and pressure sensors, the ultrasonic device can automatically switch between different operating states. This prevents localized icing caused by low-temperature refrigerant during the defrosting process of the plate heat exchanger, thereby improving the operational stability and service life of the heat pump system.

[0082] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments and claims of this application are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that, unless otherwise stated, “a plurality” means two or more; the terms “first,” “second,” “third,” etc., are used only to distinguish and not to describe a particular order or sequence, nor should they be construed as indicating or implying relative importance. The term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items. When the above description relates to drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of this application, those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0083] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A heat pump system for preventing plate heat exchangers from freezing, comprising a compressor, a four-way valve, a plate heat exchanger, a throttling assembly, and an outdoor heat exchanger connected in sequence by refrigerant circulation pipes; an ultrasonic device fixedly mounted on the end plate of the plate heat exchanger; a temperature sensor mounted on the outlet water pipe of the plate heat exchanger; a pressure sensor mounted on the return gas pipe of the compressor; and a controller electrically or communicatively connected to the four-way valve, the temperature sensor, the pressure sensor, and the ultrasonic device, characterized in that... The controller controls the ultrasound device in the following manner: Obtain the operating mode of the heat pump system. If the heat pump system is in defrost mode, obtain the outlet water temperature T of the plate heat exchanger. out If the outlet water temperature T out Less than the first outlet water temperature threshold Then the ultrasonic device will be activated; if the outlet water temperature T out Greater than or equal to the first outlet water temperature threshold Then obtain the evaporation temperature T. z And based on the outlet water temperature T out The range determines the evaporation temperature threshold T. z-set Determine the evaporation temperature T z Is it less than the evaporation temperature threshold T? z-set If yes, then start the ultrasound device; According to the outlet water temperature T out The range determines the evaporation temperature threshold T. z-set ,include: Determine the outlet water temperature T out Is it greater than or equal to the second outlet water temperature threshold? : If so, then the evaporation temperature threshold T z-set The first evaporation temperature threshold ; If not, then the evaporation temperature threshold T z-set The second evaporation temperature threshold ; First outlet water temperature threshold Less than the second outlet water temperature threshold First evaporation temperature threshold Less than the second evaporation temperature threshold ; According to the outlet water temperature T out and evaporation temperature T z Determine the operating status of the ultrasonic device, including: If the outlet water temperature T out <First outlet water temperature threshold Control the ultrasonic device to operate in the first working state; If the second outlet water temperature threshold >Outlet water temperature T out ≥ First outlet water temperature threshold And the evaporation temperature T z <Evaporation temperature threshold T z-set Control the ultrasonic device to operate in the second working state; If the outlet water temperature T out ≥Second outlet water temperature threshold And the evaporation temperature T z <Evaporation temperature threshold T z-set The ultrasonic device is controlled to operate in the third working state.

2. The heat pump system for preventing plate heat exchangers from freezing according to claim 1, characterized in that: The ultrasonic device includes a shear wave transducer for outputting shear waves, which is fixedly mounted on one end plate of the plate heat exchanger; a longitudinal wave transducer for outputting longitudinal waves, which is mounted on the other end plate of the plate heat exchanger; a shear wave generator electrically connected to the shear wave transducer; and a longitudinal wave generator electrically connected to the longitudinal wave transducer.

3. The heat pump system for preventing plate heat exchangers from freezing according to claim 2, characterized in that: The first working state is to control the transverse wave transducer to work for M1 seconds, and then switch to the longitudinal wave transducer to work for M2 seconds, with the two working alternately. The second working state is to control the transverse wave transducer to work for M3 seconds first, and then switch to the longitudinal wave transducer to work for M4 seconds, with the two working alternately. The third working state is to control the transverse wave transducer to work for M5 seconds, and then switch to the longitudinal wave transducer to work for M6 seconds, with the two working alternately. Among them, M1≥M2>M3≥M4>M5≥M6.

4. A method for controlling an ultrasonic device to prevent freezing of a plate heat exchanger, applied to a heat pump system for preventing freezing of a plate heat exchanger as described in any one of claims 1 to 3, wherein the ultrasonic device is fixedly mounted on the end plate of the plate heat exchanger, characterized in that... Includes the following control steps: S10 Obtain the operating mode of the heat pump system. If it is defrosting mode, proceed to step S20. S20 Obtains the outlet water temperature T of the plate heat exchanger out : If the outlet water temperature T out Less than the first outlet water temperature threshold Then the ultrasonic device will be activated; If the outlet water temperature T out Greater than or equal to the first outlet water temperature threshold Then proceed to step S30; S30 Obtain evaporation temperature T z And based on the outlet water temperature T out The range determines the evaporation temperature threshold T. z-set Determine the evaporation temperature T z Is it less than the evaporation temperature threshold T? z-set : If yes, then start the ultrasound device.

5. The ultrasonic device control method for preventing plate heat exchanger freezing according to claim 4, characterized in that, The water temperature T in step S30 out The range determines the evaporation temperature threshold T. z-set ,include: If the outlet water temperature T out ≥Second outlet water temperature threshold Then the evaporation temperature threshold T z-set The first evaporation temperature threshold ; If the second outlet water temperature threshold >Outlet water temperature T out ≥ First outlet water temperature threshold Then the evaporation temperature threshold T z-set The second evaporation temperature threshold ; The first evaporation temperature threshold Less than the second evaporation temperature threshold .

6. The ultrasonic device control method for preventing plate heat exchanger freezing according to claim 5, characterized in that, According to the outlet water temperature T out and evaporation temperature T z Determine the operating status of the ultrasonic device, including: If the outlet water temperature T out <First outlet water temperature threshold Control the ultrasonic device to operate in the first working state; If the second outlet water temperature threshold >Outlet water temperature T out ≥ First outlet water temperature threshold And the evaporation temperature T z <Evaporation temperature threshold T z-set Control the ultrasonic device to operate in the second working state; If the outlet water temperature T out ≥Second outlet water temperature threshold And the evaporation temperature T z <Evaporation temperature threshold T z-set The ultrasonic device is controlled to operate in the third working state.

7. The ultrasonic device control method for preventing plate heat exchangers from freezing according to claim 6, characterized in that: The ultrasonic device includes a shear wave transducer fixedly mounted on one end plate of the plate heat exchanger for outputting shear waves, a longitudinal wave transducer mounted on the other end plate of the plate heat exchanger for outputting longitudinal waves, a shear wave generator electrically connected to the shear wave transducer, and a longitudinal wave generator electrically connected to the longitudinal wave transducer. The first operating state is to control the shear wave transducer to work for M1 seconds, then switch to the longitudinal wave transducer to work for M2 seconds, and the two alternate. The second operating state is to control the shear wave transducer to work for M3 seconds, then switch to the longitudinal wave transducer to work for M4 seconds, and the two alternate. The third operating state is to control the shear wave transducer to work for M5 seconds, then switch to the longitudinal wave transducer to work for M6 seconds, and the two alternate. Wherein, M1≥M2>M3≥M4>M5≥M6.

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