Heat pump system and control method thereof

Abstract

The embodiment of the invention provides a heat pump system and a control method thereof. The heat pump system comprises a refrigerant loop and a heat pump loop, a secondary refrigerant flow path; the water side heat exchanger is provided with a refrigerant flow channel and a secondary refrigerant flow channel which are isolated from each other, the refrigerant flow channel is connected in the refrigerant loop in series, and the secondary refrigerant flow channel is connected in the secondary refrigerant flow path in series; and the bubble generating device is used for filling gas into the secondary refrigerant in the secondary refrigerant flow path so as to form bubbles in the secondary refrigerant flowing into the secondary refrigerant flow path.

Description

Technical Field

[0001] This application relates to the technical field of heat pump systems, and particularly to a heat pump system and a control method thereof. Background Art

[0002] The heat pump system is provided with a water-side heat exchanger, and heat exchange between the refrigerant and the coolant is achieved through the water-side heat exchanger. In the related art, the heat exchange performance of the water-side heat exchanger gradually decays during long-term operation, resulting in the heat exchange efficiency of the water-side heat exchanger not meeting the expectations, and the operating energy efficiency of the heat pump system being relatively low. Summary of the Invention

[0003] An embodiment of this application provides a heat pump system and a control method thereof, which can effectively improve the heat exchange performance of the water-side heat exchanger and significantly improve the operating energy efficiency of the heat pump system.

[0004] On the one hand, an embodiment of this application provides a heat pump system, including: a refrigerant circuit; a coolant flow path; a water-side heat exchanger having a refrigerant flow channel and a coolant flow channel isolated from each other, the refrigerant flow channel being connected in series in the refrigerant circuit, and the coolant flow channel being connected in series in the coolant flow path; a bubble generating device for injecting gas into the coolant in the coolant flow path to form bubbles in the coolant flowing into the coolant flow channel.

[0005] In some embodiments, the bubble generating device includes a Venturi injector and a mixer. The coolant flow channel has a coolant inlet and a coolant outlet. The Venturi injector, the mixer, and the coolant inlet are connected in series in the coolant flow path along the flow direction of the coolant. The Venturi injector is used to inject gas into the coolant in the coolant flow path to form bubbles in the coolant, and the mixer is used to uniformly mix the bubbles formed by the Venturi injector and the coolant.

[0006] In some embodiments, the bubble generating device further includes a gas-liquid separator and a gas tank. The gas-liquid separator has a liquid inlet end, a gas outlet end, and a liquid outlet end. The liquid inlet end and the liquid outlet end are respectively arranged in the coolant flow path. The liquid inlet end is connected to the coolant outlet, and the gas tank is respectively communicated with the gas outlet end and the Venturi injector.

[0007] In some embodiments, the bubble generating device further includes an ejector connected to the Venturi injector for adjusting the gas injection amount of the Venturi injector.

[0008] In some embodiments, a water pump is provided in the coolant flow path. The water pump, the Venturi injector, the mixer, and the coolant inlet are connected in series in the coolant flow path along the flow direction of the coolant.

[0009] In some embodiments, the bubble generating device is used to add inert gas to the refrigerant in the refrigerant flow path.

[0010] On the other hand, an embodiment of the present application provides a heat pump system control method, wherein the heat pump system includes a refrigerant circuit, a coolant flow path, a water-side heat exchanger and a bubble generating device, wherein the water-side heat exchanger has a refrigerant flow channel and a coolant flow channel isolated from each other, the refrigerant flow channel is connected in series in the refrigerant circuit, the coolant flow channel is connected in series in the coolant flow path, and the bubble generating device is used to add gas to the coolant in the coolant flow path to form bubbles in the coolant flowing into the coolant flow path, and the heat pump system control method includes: determining the heat exchange efficiency of the water-side heat exchanger; and controlling the bubble generation rate of the bubble generating device according to the heat exchange efficiency of the water-side heat exchanger.

[0011] In some embodiments, the heat exchange efficiency of the water side heat exchanger includes the inlet and outlet water temperature difference of the water side heat exchanger; determining the heat exchange efficiency of the water side heat exchanger includes: obtaining the inlet water temperature and the outlet water temperature of the water side heat exchanger; and determining the inlet and outlet water temperature difference of the water side heat exchanger based on the inlet water temperature and the outlet water temperature.

[0012] In some embodiments, the heat exchange efficiency of the water side heat exchanger includes the condensing heat exchange temperature difference of the water side heat exchanger; determining the heat exchange efficiency of the water side heat exchanger includes: when the heat pump system is in a heating operation mode, obtaining the outlet water temperature of the water side heat exchanger and the high-pressure side refrigerant saturation temperature of the refrigerant circuit; determining the condensing heat exchange temperature difference of the water side heat exchanger based on the high-pressure side refrigerant saturation temperature and the outlet water temperature.

[0013] In some embodiments, the heat exchange efficiency of the water side heat exchanger includes the evaporation heat exchange temperature difference of the water side heat exchanger; determining the heat exchange efficiency of the water side heat exchanger includes: when the heat pump system is in a cooling operation mode, obtaining the inlet water temperature of the water side heat exchanger and the low-pressure side refrigerant saturation temperature of the refrigerant circuit; determining the evaporation heat exchange temperature difference of the water side heat exchanger based on the inlet water temperature and the low-pressure side refrigerant saturation temperature.

[0014] The embodiment of the present application sets a bubble generating device, and uses the bubble generating device to inject gas into the refrigerant in the refrigerant flow path to form bubbles in the refrigerant flowing into the refrigerant flow channel; during the flow of the refrigerant in the refrigerant flow channel, the bubbles can exert a turbulent effect on the refrigerant, destroy the stable state of the boundary layer in the refrigerant, increase the flow velocity and heat exchange efficiency of the refrigerant in the refrigerant flow channel, offset the effect of the heat exchange performance attenuation of the water-side heat exchanger in long-term operation, effectively improve the heat exchange performance of the water-side heat exchanger, and significantly improve the operating energy efficiency of the heat pump system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0016] Figure 1 is the connection structure diagram of the heat pump system provided by some embodiments of the present application;

[0017] Figure 2 is the flowchart of the heat pump system control method provided by some embodiments of the present application;

[0018] Figure 3 is the partial flowchart of the heat pump system control method provided by some embodiments of the present application;

[0019] Figure 4 is another partial flowchart of the heat pump system control method provided by some embodiments of the present application;

[0020] Figure 5 is yet another partial flowchart of the heat pump system control method provided by some embodiments of the present application;

[0021] Figure 6 is still another partial flowchart of the heat pump system control method provided by some embodiments of the present application.

[0022] Description of the main reference symbols:

[0023] 1 - Heat pump system, 10 - Refrigerant circuit, 20 - Secondary refrigerant flow path, 30 - Water - side heat exchanger, 31 - Refrigerant flow channel, 32 - Secondary refrigerant flow channel, 321 - Secondary refrigerant inlet, 322 - Secondary refrigerant outlet, 40 - Bubble generating device, 41 - Venturi injector, 42 - Mixer, 43 - Gas - liquid separator, 431 - Liquid inlet end, 432 - Gas outlet end, 433 - Liquid outlet end, 44 - Gas tank, 45 - Ejector, 46 - Pressure reducing valve, 50 - Water pump. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0025] In the description of the present application, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, "a plurality" means two or more, unless otherwise specifically defined.

[0026] "A and / or B" includes the following three combinations: only A, only B, and the combination of A and B.

[0027] The use of "suitable for" or "configured to" in the present application means open and inclusive language, which does not exclude a device that is suitable for or configured to perform additional tasks or steps. Additionally, the use of "based on" means open and inclusive because a process, step, calculation, or other action "based on" one or more of the said conditions or values can in practice be based on additional conditions or values beyond those stated.

[0028] In the present application, the term "exemplary" is used to mean "serving as an example, illustration, or demonstration". Any embodiment described as "exemplary" in the present application is not necessarily to be construed as more preferred or more advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use the present application. In the following description, details are set forth for the purpose of explanation. It should be understood that those of ordinary skill in the art can recognize that the present application can be implemented without the use of these specific details. In other instances, well-known structures and processes are not described in detail to avoid unnecessary details from obscuring the description of the present application. Therefore, the present application is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed in the present application.

[0029] As Figure 1 shown, on the one hand, an embodiment of the present application provides a heat pump system 1, which includes a refrigerant circuit 10, a secondary coolant flow path 20, a water-side heat exchanger 30, and a bubble generating device 40, and can effectively improve the heat exchange performance of the water-side heat exchanger 30 and significantly improve the operating energy efficiency of the heat pump system 1.

[0030] The refrigerant circuit 10 is used to generate cooling capacity and provide the cooling capacity to the secondary refrigerant flow path 20 through the water-side heat exchanger 30. After obtaining the required cooling capacity from the refrigerant circuit 10, the secondary refrigerant flow path 20 can provide the required cooling capacity to the target indoor area or provide the required hot water to the user, so as to increase or decrease the air temperature of the target indoor area or meet the need for domestic hot water use. The secondary refrigerant flow path 20 may include at least one of an open branch and a closed loop. The open branch may be used to meet the need for domestic hot water use, and the closed loop may be used to increase or decrease the air temperature of the target indoor area. The embodiments of the present application do not limit this.

[0031] The water-side heat exchanger 30 has a refrigerant flow channel 31 and a secondary refrigerant flow channel 32 that are isolated from each other. The refrigerant flow channel 31 is connected in series in the refrigerant circuit 10, and the secondary refrigerant flow channel 32 is connected in series in the secondary refrigerant flow path 20. Here, the refrigerant in the refrigerant circuit 10 can flow through the refrigerant flow channel 31, and the secondary refrigerant in the secondary refrigerant flow path 20 can flow through the secondary refrigerant flow channel 32. The refrigerant exchanges heat with the secondary refrigerant through the water-side heat exchanger 30, so that the refrigerant circuit 10 provides the cooling capacity to the secondary refrigerant flow path 20 through the water-side heat exchanger 30.

[0032] The bubble generating device 40 is used to inject gas into the secondary refrigerant in the secondary refrigerant flow path 20 to form bubbles in the secondary refrigerant flowing into the secondary refrigerant flow channel 32. In this way, the bubbles can be mixed in the secondary refrigerant and flow into the secondary refrigerant flow channel 32 together with the secondary refrigerant; during this process, the bubbles can exert a turbulent flow effect on the secondary refrigerant, destroy the stable state of the boundary layer in the secondary refrigerant, increase the flow velocity and heat transfer efficiency of the secondary refrigerant in the secondary refrigerant flow channel 32, offset the influence of the heat transfer performance attenuation of the water-side heat exchanger 30 during long-term operation, effectively improve the heat transfer performance of the water-side heat exchanger 30, and significantly improve the operating energy efficiency of the heat pump system 1. In addition, due to the relatively high flow velocity of the secondary refrigerant, the risk of deposition of impurities in the secondary refrigerant on the side walls of the pipeline of the secondary refrigerant flow path 20 and the side walls of the secondary refrigerant flow channel 32 can be reduced, thereby reducing the risk of scale formation due to impurity deposition, and thus reducing the risk of attenuation of the heat transfer performance of the water-side heat exchanger 30 due to scale, and improving the heat transfer performance of the water-side heat exchanger 30.

[0033] The type of gas added to the bubble generating device 40 can be determined according to actual needs, and the embodiments of the present application do not limit this. In some embodiments, the bubble generating device 40 can be used to add inert gas to the refrigerant in the refrigerant flow path 20. The inert gas can be, for example, nitrogen, argon, etc. The inert gas can protect the side walls of the pipe of the refrigerant flow path 20 and the side walls of the refrigerant flow channel 32, preventing impurities / oxygen that may exist in the refrigerant from contacting the side walls of the pipe of the refrigerant flow path 20 and the side walls of the refrigerant flow channel 32, thereby preventing the side walls of the pipe of the refrigerant flow path 20 and the side walls of the refrigerant flow channel 32 from forming scale or being damaged by oxygen erosion, further reducing the decay rate of the heat exchange performance of the water-side heat exchanger 30, and improving the heat exchange performance of the water-side heat exchanger 30.

[0034] The structure of the bubble generating device 40 can be determined according to actual needs, and the embodiment of the present application does not limit this. In some embodiments, the bubble generating device 40 may include a venturi gas injector 41 and a mixer 42, and the refrigerant flow channel 32 has a refrigerant inlet 321 and a refrigerant outlet 322. The venturi gas injector 41, the mixer 42 and the refrigerant inlet 321 are sequentially connected in series in the refrigerant flow path 20 along the flow direction of the refrigerant, and the venturi gas injector 41 is used to inject gas into the refrigerant in the refrigerant flow path 20 to form bubbles in the refrigerant, and the mixer 42 is used to uniformly mix the bubbles formed by the venturi gas injector 41 and the refrigerant. In this way, the refrigerant uniformly mixed with bubbles can enter the refrigerant flow channel 32 through the refrigerant inlet 321, and the turbulent effect of the bubbles is used to improve the flow velocity and heat exchange efficiency of the refrigerant in the refrigerant flow channel 32, effectively improve the heat exchange performance of the water-side heat exchanger 30, and significantly improve the operating energy efficiency of the heat pump system 1. The type of the mixer 42 can be determined according to actual needs, and the embodiment of the present application does not limit this; illustratively, the mixer 42 can be a static mixer.

[0035] In some examples, the bubble generating device 40 may further include a gas-liquid separator 43 and a gas tank 44. The gas-liquid separator 43 has a liquid inlet end 431, a gas outlet end 432, and a liquid outlet end 433. The liquid inlet end 431 and the liquid outlet end 433 are respectively arranged in the coolant flow path 20. The liquid inlet end 431 is connected to the coolant outlet 322. The gas tank 44 is respectively communicated with the gas outlet end 432 and the Venturi injector 41. Here, the coolant flowing out of the coolant flow channel 32 can flow into the gas-liquid separator 43 through the liquid inlet end 431. The gas-liquid separator 43 separates the gas mixed in the coolant. The separated gas can be recovered into the gas tank 44 through the gas outlet end 432 of the gas-liquid separator 43. The coolant after removing the gas can be discharged from the gas-liquid separator 43 through the liquid outlet end 433. The gas recovered into the gas tank 44 can be provided to the Venturi injector 41 again by the gas tank 44, and the Venturi injector 41 injects it into the coolant to form bubbles. By providing the gas-liquid separator 43 and the gas tank 44, the recovery and recycling of the gas can be realized, and a relatively closed gas circulation environment can be formed by the bubble generating device 40, avoiding the intrusion of external air into the water-side heat exchanger 30 and the erosion damage caused to the water-side heat exchanger 30 thereby, further reducing the attenuation speed of the heat exchange performance of the water-side heat exchanger 30 and improving the heat exchange performance of the water-side heat exchanger 30. Exemplarily, the bubble generating device 40 may further include a pressure reducing valve 46, and the pressure reducing valve 46 is arranged at the exhaust port of the bubble generating device 40.

[0036] In some examples, the bubble generating device 40 may further include an ejector 45. The ejector 45 is connected to the Venturi injector 41 and is used to adjust the gas injection amount of the Venturi injector 41. Exemplarily, the ejector 45 may be arranged between the gas tank 44 and the Venturi injector 41 as described above to inject the gas in the gas tank 44 into the Venturi injector 41 according to the required gas injection amount, so that the Venturi injector 41 injects the required gas injection amount into the coolant. Here, the gas injection amount may be the gas flow rate injected by the Venturi injector 41 into the coolant per unit time. Exemplarily, the ejector 45 may be an electric ejector, so that the controller of the heat pump system 1 can control the injection amount of the electric ejector in real time to achieve real-time precise control.

[0037] In some examples, a water pump 50 may be provided in the coolant flow path 20. The water pump 50, the Venturi injector 41, the mixer 42, and the coolant inlet 321 are connected in series in the coolant flow path 20 in sequence along the flow direction of the coolant. The coolant is driven by the water pump 50 to flow through the Venturi injector 41, the mixer 42, and the water-side heat exchanger 30 in sequence.

[0038] As Figure 2 shown, on the other hand, the embodiment of the present application provides a control method for a heat pump system 1, which is used to control the above heat pump system 1. The control method of the heat pump system 1 includes S10 to S20.

[0039] S10: Determine the heat exchange efficiency of the water-side heat exchanger 30. Here, the heat exchange efficiency of the water-side heat exchanger 30 can be determined by different calculation methods, which are not limited in the embodiments of the present application.

[0040] S20: Control the bubble generation rate of the bubble generation device 40 according to the heat exchange efficiency of the water-side heat exchanger 30. Here, when the heat exchange efficiency of the water-side heat exchanger 30 is low, the bubble generation device 40 can be controlled to maintain a relatively large working power and bubble generation rate, so as to quickly increase the amount of bubbles in the coolant and the turbulence effect of the bubbles on the coolant, thereby quickly increasing the flow velocity and heat exchange efficiency of the coolant in the coolant flow channel 32, and thus improving the heat exchange efficiency of the water-side heat exchanger 30. When the heat exchange efficiency of the water-side heat exchanger 30 is high, the bubble generation device 40 can be controlled to maintain a relatively small working power and bubble generation rate, so as to control the amount of bubbles in the coolant and the turbulence effect of the bubbles on the coolant to a matching level, avoid excessive turbulence caused by too many bubbles, and can avoid excessive energy consumption of the bubble generation device 40, reducing the operating energy consumption of the heat pump system 1.

[0041] The parameter types included in the heat exchange efficiency of the water-side heat exchanger 30 can be determined according to actual needs, and can include, for example, at least one of the temperature difference between the inlet and outlet water of the water-side heat exchanger 30, the condensation heat exchange temperature difference of the water-side heat exchanger 30, and the evaporation heat exchange temperature difference of the water-side heat exchanger 30, which are not limited in the embodiments of the present application.

[0042] In some embodiments, the heat exchange efficiency of the water-side heat exchanger 30 can include the temperature difference between the inlet and outlet water of the water-side heat exchanger 30. As Figure 3 shown, correspondingly, S10 can include S11' to S12'.

[0043] S11': Obtain the inlet water temperature and outlet water temperature of the water-side heat exchanger 30.

[0044] Here, the inlet water temperature of the water-side heat exchanger 30 can be measured by a temperature sensor disposed at the coolant inlet 321, and the outlet water temperature can be measured by a temperature sensor disposed at the coolant outlet 322.

[0045] S12': Determine the temperature difference between the inlet and outlet water of the water-side heat exchanger 30 according to the inlet water temperature and the outlet water temperature.

[0046] In some examples, S20 can include S21.

[0047] S21: Control the bubble generation rate of the bubble generation device 40 according to the temperature difference between the inlet and outlet water, so that the temperature difference between the inlet and outlet water is greater than or equal to the lower limit of the temperature difference between the inlet and outlet water.

[0048] Here, the ideal inlet and outlet water temperature difference of the water-side heat exchanger 30 under different operating parameters can be determined in advance, and the threshold value of the attenuation amplitude of the inlet and outlet water temperature difference can be set in advance according to actual needs. During actual operation, the ideal inlet and outlet water temperature difference of the water-side heat exchanger 30 under the actual operating parameters of the heat pump system 1 can be determined according to the actual operating parameters of the heat pump system 1, and the lower limit of the inlet and outlet water temperature difference can be determined according to the ideal inlet and outlet water temperature difference and the threshold value of the attenuation amplitude of the heat transfer efficiency; exemplarily, the lower limit of the inlet and outlet water temperature difference can be the product of the ideal inlet and outlet water temperature difference and the threshold value of the attenuation amplitude of the heat transfer efficiency. The value of the threshold value of the attenuation amplitude of the heat transfer efficiency can be determined according to actual needs, and the embodiments of the present application do not limit this; exemplarily, the threshold value of the attenuation amplitude of the heat transfer efficiency can be set to 10% to 30%.

[0049] When the inlet and outlet water temperature difference is less than the lower limit of the inlet and outlet water temperature difference, the bubble generating device 40 can be controlled to maintain a relatively large working power and bubble generation rate, so as to quickly increase the amount of bubbles in the coolant and the turbulent flow effect of the bubbles on the coolant, and then quickly increase the flow velocity and heat transfer efficiency of the coolant in the coolant flow channel 32, thereby improving the heat transfer efficiency of the water-side heat exchanger 30, so that the inlet and outlet water temperature difference is greater than or equal to the lower limit of the inlet and outlet water temperature difference.

[0050] In some embodiments, the heat transfer efficiency of the water-side heat exchanger 30 may include the condensation heat transfer temperature difference of the water-side heat exchanger 30. As Figure 4 shown, correspondingly, S10 may include S11” to S12”.

[0051] S11”: When the heat pump system 1 is in the heating operation mode, obtain the outlet water temperature of the water-side heat exchanger 30 and the saturated temperature of the refrigerant on the high-pressure side of the refrigerant circuit 10.

[0052] Here, the saturated temperature of the refrigerant on the high-pressure side of the refrigerant circuit 10 can be calculated and determined according to the high-pressure side refrigerant pressure of the refrigerant circuit 10.

[0053] S12”: Determine the condensation heat transfer temperature difference of the water-side heat exchanger 30 according to the saturated temperature of the refrigerant on the high-pressure side and the outlet water temperature. Here, the condensation heat transfer temperature difference of the water-side heat exchanger 30 can be the difference between the saturated temperature of the refrigerant on the high-pressure side and the outlet water temperature.

[0054] In some examples, S20 may include S22.

[0055] S22: Control the bubble generation rate of the bubble generating device 40 according to the condensation heat transfer temperature difference, so that the condensation heat transfer temperature difference is greater than or equal to the lower limit of the condensation heat transfer temperature difference.

[0056] Here, the ideal condensation heat transfer temperature difference of the water-side heat exchanger 30 under different operating parameters can be determined in advance, and the threshold value of the attenuation amplitude of the condensation heat transfer temperature difference can be set in advance according to actual needs. During actual operation, the ideal condensation heat transfer temperature difference of the water-side heat exchanger 30 under the actual operating parameters of the heat pump system 1 can be determined according to the actual operating parameters of the heat pump system 1, and the lower limit of the condensation heat transfer temperature difference can be determined according to the ideal condensation heat transfer temperature difference and the threshold value of the attenuation amplitude of the condensation heat transfer temperature difference; Exemplarily, the lower limit of the condensation heat transfer temperature difference can be the product of the ideal condensation heat transfer temperature difference and the threshold value of the attenuation amplitude of the condensation heat transfer temperature difference. The value of the threshold value of the attenuation amplitude of the condensation heat transfer temperature difference can be determined according to actual needs, and the embodiments of the present application do not limit this; Exemplarily, the threshold value of the attenuation amplitude of the condensation heat transfer temperature difference can be set to 10% - 30%.

[0057] When the condensation heat transfer temperature difference is less than the lower limit of the condensation heat transfer temperature difference, the bubble generating device 40 can be controlled to maintain a relatively large working power and bubble generation rate, quickly increasing the amount of bubbles in the coolant and the turbulence effect of the bubbles on the coolant, thereby quickly increasing the flow velocity and heat transfer efficiency of the coolant in the coolant flow channel 32, thereby improving the heat transfer efficiency of the water-side heat exchanger 30, so that the condensation heat transfer temperature difference is greater than or equal to the lower limit of the condensation heat transfer temperature difference.

[0058] In some embodiments, the heat transfer efficiency of the water-side heat exchanger 30 may include the evaporation heat transfer temperature difference of the water-side heat exchanger 30. As Figure 5 shown, correspondingly, S10 may include S11”' to S12”'.

[0059] S11”': When the heat pump system 1 is in the refrigeration operation mode, obtain the inlet water temperature of the water-side heat exchanger 30 and the saturated temperature of the refrigerant on the low-pressure side of the refrigerant circuit 10.

[0060] Here, the saturated temperature of the refrigerant on the low-pressure side of the refrigerant circuit 10 can be calculated and determined according to the low-pressure side refrigerant pressure of the refrigerant circuit 10.

[0061] S12”': Determine the evaporation heat transfer temperature difference of the water-side heat exchanger 30 according to the inlet water temperature and the saturated temperature of the refrigerant on the low-pressure side. Here, the evaporation heat transfer temperature difference of the water-side heat exchanger 30 can be the difference between the inlet water temperature and the saturated temperature of the refrigerant on the low-pressure side.

[0062] In some examples, S20 may include S23.

[0063] S23: Control the bubble generation rate of the bubble generating device 40 according to the evaporation heat transfer temperature difference, so that the evaporation heat transfer temperature difference is greater than or equal to the lower limit of the evaporation heat transfer temperature difference.

[0064] Here, the ideal evaporation heat transfer temperature difference of the water-side heat exchanger 30 under different operating parameters can be determined in advance, and the threshold value of the attenuation amplitude of the evaporation heat transfer temperature difference can be set in advance according to actual needs. During actual operation, the ideal evaporation heat transfer temperature difference of the water-side heat exchanger 30 under the actual operating parameters of the heat pump system 1 can be determined according to the actual operating parameters of the heat pump system 1, and the lower limit of the evaporation heat transfer temperature difference can be determined according to the ideal evaporation heat transfer temperature difference and the threshold value of the attenuation amplitude of the evaporation heat transfer temperature difference; Exemplarily, the lower limit of the evaporation heat transfer temperature difference can be the product of the ideal evaporation heat transfer temperature difference and the threshold value of the attenuation amplitude of the evaporation heat transfer temperature difference. The value of the threshold value of the attenuation amplitude of the evaporation heat transfer temperature difference can be determined according to actual needs, and the embodiments of the present application do not limit this; Exemplarily, the threshold value of the attenuation amplitude of the evaporation heat transfer temperature difference can be set to 10% - 30%.

[0065] When the evaporation heat transfer temperature difference is less than the lower limit of the evaporation heat transfer temperature difference, the bubble generating device 40 can be controlled to maintain a relatively large working power and bubble generation rate, quickly increasing the amount of bubbles in the coolant and the turbulent flow effect of the bubbles on the coolant, thereby quickly increasing the flow rate and heat transfer efficiency of the coolant in the coolant flow channel 32, so as to improve the heat transfer efficiency of the water-side heat exchanger 30, making the evaporation heat transfer temperature difference greater than or equal to the lower limit of the evaporation heat transfer temperature difference.

[0066] In some embodiments, the heat transfer efficiency of the water-side heat exchanger 30 may include the temperature difference between the inlet and outlet water of the water-side heat exchanger 30, the condensation heat transfer temperature difference, and the evaporation heat transfer temperature difference. As Figure 6 shown, correspondingly, S10 may include S11 - S15.

[0067] S11: Obtain the inlet water temperature and outlet water temperature of the water-side heat exchanger 30, the saturated temperature of the refrigerant on the low-pressure side or the high-pressure side of the refrigerant circuit 10.

[0068] Here, when the heat pump system 1 is in the heating operation mode, the inlet water temperature and outlet water temperature of the water-side heat exchanger 30 and the saturated temperature of the refrigerant on the high-pressure side of the refrigerant circuit 10 can be obtained. When the heat pump system 1 is in the cooling operation mode, the inlet water temperature and outlet water temperature of the water-side heat exchanger 30 and the saturated temperature of the refrigerant on the low-pressure side of the refrigerant circuit 10 can be obtained.

[0069] S12: When the heat pump system 1 is in the heating operation mode, determine the temperature difference between the inlet and outlet water of the water-side heat exchanger 30 according to the inlet water temperature and outlet water temperature of the water-side heat exchanger 30, and determine the condensation heat transfer temperature difference of the water-side heat exchanger 30 according to the outlet water temperature of the water-side heat exchanger 30 and the saturated temperature of the refrigerant on the high-pressure side of the refrigerant circuit 10. Here, the condensation heat transfer temperature difference of the water-side heat exchanger 30 can be the difference between the saturated temperature of the refrigerant on the high-pressure side and the outlet water temperature.

[0070] S13: Control the bubble generation rate of the bubble generation device 40 according to the temperature difference between the inlet and outlet water and the condensation heat exchange temperature difference, so that the temperature difference between the inlet and outlet water is greater than or equal to the lower limit of the temperature difference between the inlet and outlet water, and the condensation heat exchange temperature difference is greater than or equal to the lower limit of the condensation heat exchange temperature difference. Here, the corresponding control can be referred to the above S21 and S22 and will not be elaborated here.

[0071] S14: When the heat pump system 1 is in the refrigeration operation mode, determine the temperature difference between the inlet and outlet water of the water side heat exchanger 30 according to the inlet water temperature and the outlet water temperature of the water side heat exchanger 30, and determine the evaporation heat exchange temperature difference of the water side heat exchanger 30 according to the inlet water temperature of the water side heat exchanger 30 and the refrigerant saturation temperature on the low pressure side of the refrigerant circuit 10. Here, the evaporation heat exchange temperature difference of the water side heat exchanger 30 can be the difference between the inlet water temperature and the refrigerant saturation temperature on the low pressure side.

[0072] S15: Control the bubble generation rate of the bubble generation device 40 according to the temperature difference between the inlet and outlet water and the evaporation heat exchange temperature difference, so that the temperature difference between the inlet and outlet water is greater than or equal to the lower limit of the temperature difference between the inlet and outlet water, and the evaporation heat exchange temperature difference is greater than or equal to the lower limit of the evaporation heat exchange temperature difference. Here, the corresponding control can be referred to the above S21 and S23 and will not be elaborated here.

[0073] The above has introduced in detail the heat pump system and its control method provided by the embodiments of the present application. Specific examples are used in this article to elaborate the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A heat pump system, characterized in that, Comprising: A refrigerant circuit; A secondary refrigerant flow path; A water-side heat exchanger having a refrigerant flow channel and a secondary refrigerant flow channel isolated from each other, the refrigerant flow channel being connected in series in the refrigerant circuit, and the secondary refrigerant flow channel being connected in series in the secondary refrigerant flow path; A bubble generating device for injecting gas into the secondary refrigerant in the secondary refrigerant flow path to form bubbles in the secondary refrigerant flowing into the secondary refrigerant flow channel.

2. The heat pump system according to claim 1, characterized in that The bubble generating device includes a Venturi injector and a mixer. The secondary refrigerant flow channel has a secondary refrigerant inlet and a secondary refrigerant outlet. The Venturi injector, the mixer, and the secondary refrigerant inlet are connected in series in the secondary refrigerant flow path in the flow direction of the secondary refrigerant. The Venturi injector is used to inject gas into the secondary refrigerant in the secondary refrigerant flow path to form bubbles in the secondary refrigerant, and the mixer is used to uniformly mix the bubbles formed by the Venturi injector and the secondary refrigerant.

3. The heat pump system according to claim 2, wherein, The bubble generating device further includes a gas-liquid separator and a gas tank. The gas-liquid separator has a liquid inlet end, a gas outlet end, and a liquid outlet end. The liquid inlet end and the liquid outlet end are respectively arranged in the secondary refrigerant flow path. The liquid inlet end is connected to the secondary refrigerant outlet, and the gas tank is respectively communicated with the gas outlet end and the Venturi injector.

4. The heat pump system according to claim 2, characterized in that, The bubble generating device further includes an ejector connected to the Venturi injector for adjusting the gas injection amount of the Venturi injector.

5. The heat pump system according to claim 2, characterized in that, A water pump is provided in the secondary refrigerant flow path. The water pump, the Venturi injector, the mixer, and the secondary refrigerant inlet are connected in series in the secondary refrigerant flow path in the flow direction of the secondary refrigerant.

6. The heat pump system according to claim 1, characterized in that, The bubble generating device is used to inject an inert gas into the secondary refrigerant in the secondary refrigerant flow path.

7. A control method for a heat pump system, characterized in that, The heat pump system includes a refrigerant circuit, a secondary refrigerant flow path, a water-side heat exchanger, and a bubble generating device. The water-side heat exchanger has a refrigerant flow channel and a secondary refrigerant flow channel isolated from each other. The refrigerant flow channel is connected in series in the refrigerant circuit, and the secondary refrigerant flow channel is connected in series in the secondary refrigerant flow path. The bubble generating device is used to inject gas into the secondary refrigerant in the secondary refrigerant flow path to form bubbles in the secondary refrigerant flowing into the secondary refrigerant flow channel. The heat pump system control method includes: Determining the heat transfer efficiency of the water-side heat exchanger; Controlling the bubble generation rate of the bubble generating device according to the heat transfer efficiency of the water-side heat exchanger.

8. The control method of the heat pump system according to claim 7, characterized in that, The heat transfer efficiency of the water-side heat exchanger includes the temperature difference between the inlet water temperature and the outlet water temperature of the water-side heat exchanger; Determining the heat transfer efficiency of the water-side heat exchanger includes: Obtaining the inlet water temperature and the outlet water temperature of the water-side heat exchanger; Determining the temperature difference between the inlet water temperature and the outlet water temperature of the water-side heat exchanger according to the inlet water temperature and the outlet water temperature.

9. The control method of the heat pump system according to claim 7, characterized in that, The heat transfer efficiency of the water-side heat exchanger includes the condensation heat transfer temperature difference of the water-side heat exchanger; determining the heat transfer efficiency of the water-side heat exchanger includes: When the heat pump system is in the heating operation mode, obtaining the outlet water temperature of the water-side heat exchanger and the saturated temperature of the refrigerant on the high-pressure side of the refrigerant circuit; Determining the condensation heat transfer temperature difference of the water-side heat exchanger according to the saturated temperature of the refrigerant on the high-pressure side and the outlet water temperature.

10. The control method of the heat pump system according to claim 7, wherein The heat transfer efficiency of the water-side heat exchanger includes the evaporation heat transfer temperature difference of the water-side heat exchanger; determining the heat transfer efficiency of the water-side heat exchanger includes: When the heat pump system is in the refrigeration operation mode, obtaining the inlet water temperature of the water-side heat exchanger and the refrigerant saturation temperature on the low-pressure side of the refrigerant circuit; Determining the evaporation heat transfer temperature difference of the water-side heat exchanger according to the inlet water temperature and the refrigerant saturation temperature on the low-pressure side.

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