Heat pump system and method for controlling heat pump system

Abstract

This invention relates to the field of heat pump system technology, and particularly to a method for controlling the vapor injection enthalpy enhancement in a heat pump system and a heat pump system thereof. The method mainly includes the following steps: S1, collecting the ambient temperature Tw and the outlet water temperature Tout of the plate heat exchanger where the heat pump system is located. S2, based on the ambient temperature Tw and the outlet water temperature Tout, determining and switching between pure gas injection mode, pure liquid injection mode, or gas-liquid mixed injection mode. S3, executing the control logic corresponding to the selected injection mode by independently or collaboratively adjusting the auxiliary valves in the gas and liquid circuits to control the vapor flow rate and liquid flow rate entering the compressor's intermediate pressure chamber. Utilizing this method can improve the energy efficiency ratio and reliability of the heat pump system, extend its service life, and reduce operating costs.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat pump systems, and in particular to a heat pump system jet augmenting enthalpy control method and a heat pump system. BACKGROUND

[0002] Jet augmenting enthalpy technology is a core technical means for improving the low-temperature heating performance of a heat pump system. This technology effectively increases the circulation amount of the refrigerant of the heat pump system by supplementing medium-pressure refrigerant into the medium-pressure cavity of the compressor, significantly improves the heating capacity and operating energy efficiency ratio of the unit in a low-temperature environment, and is a key technical path to solve the heating capacity decay of the heat pump in a low-temperature working condition.

[0003] In related technologies, the heat pump system cannot regulate the gas-liquid ratio entering the compressor according to its actual working condition, so in complex working conditions such as "low ambient temperature and high outlet water temperature", the problems of insufficient jet flow leading to low efficiency or improper liquid injection leading to uncontrolled exhaust temperature are prone to occur, thereby reducing the energy efficiency ratio and reliability of the heat pump system in operation, and increasing the operating cost.

[0004] Therefore, it is urgent to design a heat pump system jet augmenting enthalpy control method and a heat pump system to solve the above technical problems. SUMMARY

[0005] The purpose of the present application is to provide a heat pump system jet augmenting enthalpy control method and a heat pump system, which can improve the energy efficiency ratio and reliability of the heat pump system, prolong the service life, and reduce the operating cost.

[0006] To achieve this purpose, the present application adopts the following technical solutions: On the one hand, the present application provides a heat pump system jet augmenting enthalpy control method, comprising the following steps: S1, collecting the ambient temperature Tw of the heat pump system and the outlet water temperature Tout of the plate heat exchanger; S2, judging and switching the pure gas injection mode, the pure liquid injection mode or the gas-liquid mixed injection mode according to the ambient temperature Tw and the outlet water temperature Tout; S3, executing the control logic corresponding to the selected injection mode: By independently adjusting or cooperatively adjusting the gas path auxiliary valve and the liquid path auxiliary valve, the jet flow and the liquid flow entering the medium-pressure cavity of the compressor are controlled.

[0007] As an optional technical solution of a heat pump system jet augmenting enthalpy control method, in step S2, the pure gas injection mode triggering condition is: The ambient temperature Tw is lower than the first preset temperature, and the outlet water temperature Tout is lower than the second preset temperature; the liquid path auxiliary valve is closed, and the jet flow is adjusted only by the gas path auxiliary valve.

[0008] As an optional technical solution of the ejector augmented heat pump system control method, in the pure gas injection mode, the target superheat degree is set based on the exhaust temperature and the compressor operating frequency, and the opening degree of the gas path auxiliary valve is adjusted according to the difference between the actual superheat degree and the target superheat degree.

[0009] As an optional technical solution of the ejector augmented heat pump system control method, in the pure gas injection mode, the opening degree adjustment of the gas path auxiliary valve includes: The current opening degree Pn of the gas path auxiliary valve is calculated as Pn=Pn-1+ΔU; ΔU=Kp×e(t); Wherein, Pn-1 is the opening degree of the gas path auxiliary valve last time; ΔU is the opening degree increment of the gas path auxiliary valve, e(t) is the difference between the actual superheat degree and the target superheat degree, and Kp is the proportional coefficient; The actual superheat degree = exhaust temperature Td - outlet water temperature Tout.

[0010] As an optional technical solution of the ejector augmented heat pump system control method, in step S2, the pure liquid injection mode triggering condition is: The ambient temperature Tw is lower than the first preset temperature, and the outlet water temperature Tout is higher than the third preset temperature; the gas path auxiliary valve is closed, and the liquid injection flow is adjusted only by the liquid path auxiliary valve.

[0011] As an optional technical solution of the ejector augmented heat pump system control method, in the pure liquid injection mode, the opening degree proportion K_liquid of the liquid path auxiliary valve is linearly adjusted according to the exhaust temperature Td: K_liquid=A×(Td-B); Wherein, A and B are preset coefficients, the opening degree proportion K_liquid of the liquid path auxiliary valve is positively correlated with the compressor exhaust temperature Td, so as to utilize the latent heat of vaporization of the liquid refrigerant to cool the compressor.

[0012] As an optional technical solution of the ejector augmented heat pump system control method, the current opening degree of the liquid path auxiliary valve is the product of the opening degree proportion K_liquid of the liquid path auxiliary valve and the maximum opening degree Pmax of the liquid path auxiliary valve; and the current opening degree of the liquid path auxiliary valve is set between 60 steps and 500 steps.

[0013] As an optional technical solution of the ejector augmented heat pump system control method, in step S2, the gas-liquid mixed injection mode triggering condition is: The ambient temperature Tw is between the first preset temperature and the fourth preset temperature, or the outlet water temperature Tout is between the second preset temperature and the third preset temperature; the gas path auxiliary valve and the liquid path auxiliary valve are opened synchronously.

[0014] As an optional technical solution of the ejector augmented heat pump system control method, in the gas-liquid mixed injection mode, the adjustment of the gas-liquid injection proportion includes: When the exhaust temperature Td is lower than the first exhaust threshold, the opening of the gas path auxiliary valve is greater than the opening of the liquid path auxiliary valve, with jet injection as the main method of increasing enthalpy and a small amount of liquid injection as an auxiliary method of cooling. When the exhaust temperature Td is between the first exhaust threshold and the second exhaust threshold, the opening of the gas circuit auxiliary valve is equal to the opening of the liquid circuit auxiliary valve, and the gas-liquid injection is balanced. When the exhaust temperature Td is higher than the second exhaust threshold, the opening of the gas path auxiliary valve is less than the opening of the liquid path auxiliary valve, and the cooling is mainly achieved by liquid injection, with a small amount of air injection to maintain the enthalpy increase.

[0015] On the other hand, the present invention provides a heat pump system, wherein the heat pump system operates using the heat pump system vapor injection enthalpy control method described in any of the above optional technical solutions; the heat pump system includes a compressor, a four-way valve, a plate heat exchanger, a flash evaporator, a finned heat exchanger, a main valve, a gas path auxiliary valve, and a liquid path auxiliary valve; The flash evaporator is equipped with a main inlet, a main outlet, a gas phase enthalpy increase port, and a liquid phase enthalpy increase port; The compressor has a medium-pressure chamber, the compressor's exhaust port is connected to the first port of the four-way valve, the second port of the four-way valve is connected to the plate heat exchanger, the third port of the four-way valve is connected to the finned heat exchanger, and the fourth port of the four-way valve is connected to the compressor's intake port. The plate heat exchanger is connected to the main inlet of the flash evaporator through the main valve, and the main outlet of the flash evaporator is connected to the finned heat exchanger. The vapor phase enthalpy-increasing port of the flash evaporator is connected to the medium-pressure chamber of the compressor through the gas path auxiliary valve; The liquid phase enthalpy-increasing port of the flash evaporator is connected to the medium-pressure chamber of the compressor through the liquid circuit auxiliary valve; and the gas circuit auxiliary valve and the liquid circuit auxiliary valve are arranged in parallel.

[0016] As an optional technical solution for a heat pump system, the heat pump system further includes a capillary tube, one end of which is connected to the outlet of the liquid circuit auxiliary valve and the other end of which is connected to the medium-pressure chamber of the compressor, and the capillary tube is arranged in parallel with the gas circuit auxiliary valve.

[0017] The beneficial effects of the present invention include at least the following: This invention provides a method for controlling the vapor injection enthalpy of a heat pump system. The method mainly includes the following steps: S1, collecting the ambient temperature Tw and the outlet water temperature Tout of the plate heat exchanger. S2, based on the ambient temperature Tw and the outlet water temperature Tout, determining and switching between pure gas injection mode, pure liquid injection mode, or gas-liquid mixed injection mode. S3, executing the control logic corresponding to the selected injection mode, controlling the vapor injection flow rate and liquid injection flow rate entering the intermediate-pressure chamber of the compressor by independently or collaboratively adjusting the auxiliary valves in the gas and liquid circuits.

[0018] The above-described heat pump system's vapor injection enthalpy control method can select and switch between pure gas injection mode, pure liquid injection mode, or gas-liquid mixed injection mode based on the ambient temperature Tw and the outlet water temperature Tout. This allows for precise control of the gas-liquid ratio entering the compressor's intermediate-pressure chamber, i.e., controlling the vapor and liquid flow rates entering the compressor's intermediate-pressure chamber. Thus, when the heat pump system operates under complex conditions such as "low ambient temperature and high outlet water temperature," it will not experience low efficiency due to insufficient vapor injection, nor will it suffer from uncontrolled exhaust temperature due to improper liquid injection. This improves the energy efficiency ratio and reliability of the heat pump system, extends its service life, and reduces operating costs.

[0019] The present invention also provides a heat pump system that enables independent control and flexible ratio of gaseous and liquid refrigerants, thereby improving the energy efficiency ratio and reliability of the heat pump system under complex operating conditions, extending its service life, and reducing operating costs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0021] Fig. 1 This is a schematic flowchart of the jet enthalpy control method for a heat pump system provided in an embodiment of the present invention; Fig. 2 This is a schematic diagram of the heat pump system provided in an embodiment of the present invention.

[0022] Figure Labels 10. Compressor; 20. Four-way valve; 30. Plate heat exchanger; 40. Flash evaporator; 41. Main inlet; 42. Main outlet; 43. Vapor phase enthalpy-increasing port; 44. Liquid phase enthalpy-increasing port; 50. Finned heat exchanger; 60. Main valve; 70. Gas path auxiliary valve; 80. Liquid path auxiliary valve; 90. Capillary tube. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0026] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0029] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0031] This embodiment provides a method for controlling the vapor injection enthalpy of a heat pump system, which can improve the energy efficiency ratio and reliability of the heat pump system, extend its service life, and reduce operating costs.

[0032] like Figs. 1-2 As shown, this embodiment provides a method for controlling the vapor injection enthalpy enhancement of a heat pump system, applicable to heat pump systems with dual-path vapor injection enthalpy enhancement functionality. The heat pump system includes a compressor 10, a four-way valve 20, a plate heat exchanger 30, a flash evaporator 40, a finned heat exchanger 50, a main valve 60, a gas-path auxiliary valve 70, and a liquid-path auxiliary valve 80. The flash evaporator 40 adopts a four-port structure, including a main inlet 41, a main outlet 42, a vapor phase enthalpy enhancement port 43, and a liquid phase enthalpy enhancement port 44. The vapor phase enthalpy enhancement port 43 is connected to the intermediate-pressure chamber of the compressor 10 via the gas-path auxiliary valve 70, and the liquid phase enthalpy enhancement port 44 is connected to the intermediate-pressure chamber of the compressor 10 via the liquid-path auxiliary valve 80. The gas-path auxiliary valve 70 and the liquid-path auxiliary valve 80 are arranged in parallel.

[0033] The heat pump system jet enthalpy control method mainly includes the following steps: S1. Collect the ambient temperature Tw of the heat pump system and the outlet water temperature Tout of the plate heat exchanger 30. Specifically, the ambient temperature sensor is set at the air inlet of the outdoor unit to detect the ambient temperature Tw; the outlet water temperature sensor is set at the outlet of the plate heat exchanger 30 to detect the outlet water temperature Tout of the plate heat exchanger 30.

[0034] S2. Based on the ambient temperature Tw and the outlet water temperature Tout, determine and switch between pure gas injection mode, pure liquid injection mode, or gas-liquid mixed injection mode.

[0035] S3. Execute the control logic corresponding to the selected injection mode, and control the jet flow rate and liquid flow rate entering the medium-pressure chamber of the compressor 10 by independently or collaboratively adjusting the gas auxiliary valve 70 and the liquid auxiliary valve 80.

[0036] Based on the above design, the heat pump system's vapor injection enthalpy control method can actively select and switch between pure gas injection mode, pure liquid injection mode, or gas-liquid mixed injection mode according to the ambient temperature Tw and the outlet water temperature Tout. This allows for precise control of the gas-liquid ratio entering the compressor 10, that is, control of the vapor injection flow rate and liquid injection flow rate entering the intermediate pressure chamber of the compressor 10. Thus, when the heat pump system is under complex operating conditions such as "low ambient temperature and high outlet water", the heat pump system will not experience problems such as insufficient vapor injection leading to low efficiency, nor will it experience problems such as improper liquid injection leading to uncontrolled exhaust temperature. This improves the energy efficiency ratio and reliability of the heat pump system, extends its service life, and reduces operating costs.

[0037] Specifically, in step S2, based on the collected ambient temperature Tw and outlet water temperature Tout, the current operating condition is determined and the corresponding injection mode is switched: When the ambient temperature Tw is lower than the first preset temperature and the outlet water temperature Tout is lower than the second preset temperature, the heat pump system is determined to be in a low-temperature, low-load operating condition and switches to pure gas injection mode. In pure gas injection mode, the liquid circuit auxiliary valve 80 is closed, and the jet flow rate is adjusted only through the gas circuit auxiliary valve 70 to increase the heating capacity of the heat pump system by utilizing the enthalpy-increasing effect of the gaseous refrigerant. When the ambient temperature Tw is lower than the first preset temperature and the outlet water temperature Tout is higher than the third preset temperature, the heat pump system is determined to be in a low-temperature, high-load operating condition and switches to pure liquid injection mode. In pure liquid injection mode, the gas circuit auxiliary valve 70 is closed, and the injection flow rate is adjusted only through the liquid circuit auxiliary valve 80 to reduce the exhaust temperature of the compressor 10 by utilizing the latent heat of vaporization of the liquid refrigerant.

[0038] When the ambient temperature Tw is between the first preset temperature and the fourth preset temperature, or the outlet water temperature Tout is between the second preset temperature and the third preset temperature, it is determined to be a transitional operating condition, and the system switches to the gas-liquid mixed injection mode. In the gas-liquid mixed injection mode, the gas circuit auxiliary valve 70 and the liquid circuit auxiliary valve 80 are opened simultaneously to coordinately adjust the gas-liquid injection ratio, thus balancing enthalpy increase and cooling effect.

[0039] For example, the triggering conditions for the pure gas injection mode are: The first preset temperature is set to -20℃, and the second preset temperature is set to 45℃. When the ambient temperature Tw≤-20℃ and the outlet water temperature Tout≤45℃, it is determined to be a low-load operating condition in a cold environment, and the pure gas injection mode is switched at this time.

[0040] In pure gas injection mode, the target superheat is set based on the exhaust temperature Td and the operating frequency of compressor 10. The opening of the auxiliary gas valve 70 is adjusted according to the difference between the actual superheat and the target superheat. Specifically, the exhaust temperature is divided into multiple ranges, and differentiated target superheat values ​​are set based on the operating frequency. The higher the exhaust temperature and the higher the operating frequency, the larger the target superheat setting value. This segmented setting method takes into account both the compressor 10's superheat tolerance requirements under high exhaust temperature and high operating frequency conditions, and the need for energy efficiency optimization under low exhaust temperature and low operating frequency conditions.

[0041] The relationship between the target superheat, exhaust temperature Td, and operating frequency of compressor 10 is shown in Table 1: In pure gas injection mode, the opening adjustment of the gas circuit auxiliary valve 70 includes the following steps: Calculate the current opening degree of the auxiliary gas valve 70: Pn = Pn-1 + ΔU. Where ΔU = Kp × e(t), Pn-1 is the previous opening degree of the auxiliary gas valve 70; ΔU is the opening increment of the auxiliary gas valve 70; e(t) is the difference between the actual superheat and the target superheat; Kp is the proportionality coefficient; actual superheat = exhaust temperature Td - outlet water temperature Tout.

[0042] Through the above control method, when the actual superheat is higher than the target superheat, the value of e(t) increases, the opening degree of the auxiliary valve 70 increases, the jet flow rate increases, the enthalpy enhancement effect is enhanced, the exhaust temperature decreases, and the actual superheat decreases accordingly. When the actual superheat is lower than the target superheat, the value of e(t) decreases, the opening degree of the auxiliary valve 70 decreases, the jet flow rate decreases, and the energy efficiency decreases due to excessive gas injection is prevented. This closed-loop control mechanism ensures that the actual superheat always approaches the target superheat, achieving precise adjustment of the jet flow rate.

[0043] By adjusting the opening of the auxiliary gas valve 70 in the pure gas injection mode, the pure gas injection mode can ensure sufficient enthalpy increase of the gas jet to improve heating performance under extremely cold and low load conditions, while avoiding energy efficiency loss caused by excessive gas replenishment. At the same time, the precise control of superheat prevents the compressor 10 from experiencing liquid slugging risk.

[0044] In this embodiment, the incremental ΔU of the gas path auxiliary valve 70 is calculated as follows: Where Kp is the proportional gain coefficient, Kp=1; Ti is the integral time coefficient, Ti=2; Td is the derivative time coefficient, Td=3; e(t-1) is the difference between the previous actual superheat and the previous target superheat; e(t-2) is the difference between the previous two actual superheat and the previous two target superheat; T is the sampling period, default 15s.

[0045] In step S2, the first preset temperature is set to -20℃ and the third preset temperature is set to 50℃. When the ambient temperature Tw≤-20℃ and the outlet water temperature Tout≥50℃, it is determined to be a high-load operating condition in a frigid environment, and at this time, the system switches to pure liquid injection mode.

[0046] The opening adjustment method of the hydraulic auxiliary valve 80 is as follows: The opening ratio K_liquid of the auxiliary liquid valve 80 is linearly adjusted according to the exhaust temperature Td, using the formula K_liquid=A×(Td-B), where A and B are preset coefficients. This linear relationship ensures that the opening ratio of the auxiliary liquid valve 80 is positively correlated with the exhaust temperature of the compressor 10. The higher the exhaust temperature, the larger the opening of the auxiliary liquid valve 80, and the more liquid is injected, utilizing the latent heat of vaporization of the liquid refrigerant to rapidly cool the compressor 10.

[0047] Specifically, setting A=1.5 and B=86.7, then when the exhaust temperature Td=100℃, K_liquid=20%; when the exhaust temperature Td=120℃, K_liquid=80%. The current opening degree of the auxiliary valve 80 is the product of the opening ratio K_liquid and the maximum opening degree Pmax, and the current opening degree is limited between the minimum opening degree Pmin and the maximum opening degree Pmax. Setting Pmax=500 steps and Pmin=60 steps, then the current opening degree range is 60 steps to 500 steps.

[0048] By linearly adjusting the discharge temperature in tandem with the opening degree of the auxiliary valve in the liquid circuit (80°C), the pure liquid injection mode can dynamically adjust the injection volume according to the actual heat load of the compressor 10 under extremely cold and high-load conditions, achieving a balance between rapid cooling and energy efficiency optimization. The limitation of the opening range prevents valve malfunction under extreme conditions, ensuring the operational stability of the heat pump system.

[0049] In step S2, the first preset temperature is set to -20℃, the fourth preset temperature is set to 10℃, the second preset temperature is set to 45℃, and the third preset temperature is set to 50℃. When -20℃ < Tw < 10℃ or 45℃ < Tout < 50℃, it is determined to be a transitional working condition. At this time, the system switches to the gas-liquid mixing injection mode, and the gas auxiliary valve 70 and the liquid auxiliary valve 80 are opened simultaneously.

[0050] In the gas-liquid mixed injection mode, the adjustment of the gas-liquid injection ratio includes: When the exhaust temperature Td is lower than the first exhaust threshold, the opening of the gas path auxiliary valve 70 is greater than the opening of the liquid path auxiliary valve 80, with jet injection as the main method to increase enthalpy and a small amount of liquid injection to assist in cooling.

[0051] When the exhaust temperature Td is between the first exhaust threshold and the second exhaust threshold, the opening of the gas path auxiliary valve 70 is equal to the opening of the liquid path auxiliary valve 80, and the gas-liquid injection is balanced.

[0052] When the exhaust temperature Td is higher than the second exhaust threshold, the opening of the gas path auxiliary valve 70 is less than the opening of the liquid path auxiliary valve 80, and the cooling is mainly achieved by liquid injection, with a small amount of air injection to maintain the enthalpy increase.

[0053] Specifically, the first exhaust threshold is set to 100℃, and the second exhaust threshold is set to 110℃. Based on the range of exhaust temperature Td, the opening ratio of the gas path auxiliary valve 70 and the liquid path auxiliary valve 80 is dynamically adjusted. When the exhaust temperature Td ≤ 100℃, the opening ratio of the gas-circuit auxiliary valve 70 is greater than that of the liquid-circuit auxiliary valve 80, and the gas-liquid injection ratio is 6:2. The system primarily uses gas injection to increase enthalpy, with a small amount of liquid injection assisting in cooling. At this time, the heat pump system prioritizes the enthalpy-increasing effect of the gaseous refrigerant to increase heating capacity, while preventing the exhaust temperature from rising too quickly through a small amount of liquid injection.

[0054] When 100℃ < Td ≤ 110℃, the opening ratio of the gas-circuit auxiliary valve 70 is equal to that of the liquid-circuit auxiliary valve 80, resulting in a gas-liquid injection ratio of 4:4. This achieves balanced gas-liquid injection, balancing enthalpy increase and cooling effect. At this time, the heat pump system increases the liquid injection volume while ensuring a certain enthalpy increase to control the exhaust temperature within a reasonable range.

[0055] When the exhaust temperature Td > 110℃, the opening ratio of the gas-circuit auxiliary valve 70 is less than that of the liquid-circuit auxiliary valve 80, and the gas-liquid injection ratio is 2:6. Liquid injection is the main cooling method, while a small amount of air injection is used to maintain enthalpy increase. At this time, the heat pump system prioritizes the reliability of the compressor 10, rapidly reducing the exhaust temperature through a large amount of liquid injection, while maintaining a small amount of air injection to avoid completely losing the enthalpy increase effect.

[0056] Furthermore, in the gas-liquid mixed injection mode, the sum of the opening ratio K_gas of the gas auxiliary valve 70 and the opening ratio K_liquid of the liquid auxiliary valve 80 is set to a fixed value, specifically K_gas + K_liquid = 80%. This constraint ensures that the total injection flow rate of the heat pump system remains stable during the dynamic adjustment of the gas-liquid ratio, avoiding the risk of flow fluctuations and operational instability caused by the switching of the gas-liquid ratio.

[0057] It should be noted that the relationship between the opening ratio K_gas of the auxiliary gas valve 70, the current opening Pn of the auxiliary gas valve 70, and the maximum opening Pmax of the auxiliary gas valve 70 is K_gas = Pn / Pmax.

[0058] By combining gas-liquid ratio regulation with total flow rate stability constraint, the gas-liquid mixed injection mode can achieve dynamic balance between enthalpy increase and cooling under transition conditions. This avoids the risk of exhaust temperature runaway in pure gas injection mode and the problem of insufficient enthalpy increase in pure liquid injection mode. At the same time, the stable control of total injection flow rate ensures the continuity and reliability of the heat pump system operation.

[0059] like Fig. 2 As shown, this embodiment also provides a heat pump system that operates using the aforementioned heat pump system vapor injection enthalpy control method. The heat pump system includes a compressor 10, a four-way valve 20, a plate heat exchanger 30, a flash evaporator 40, a finned heat exchanger 50, a main valve 60, a gas-phase auxiliary valve 70, and a liquid-phase auxiliary valve 80. The flash evaporator 40 is provided with a main inlet 41, a main outlet 42, a vapor phase enthalpy enhancement port 43, and a liquid phase enthalpy enhancement port 44. The compressor 10 has a medium-pressure chamber. The exhaust port of the compressor 10 is connected to the first port of the four-way valve 20, the second port of the four-way valve 20 is connected to the plate heat exchanger 30, the third port of the four-way valve 20 is connected to the finned heat exchanger 50, and the fourth port of the four-way valve 20 is connected to the suction port of the compressor 10. Plate heat exchanger 30 is connected to the main inlet 41 of flash evaporator 40 via main valve 60, and the main outlet 42 of flash evaporator 40 is connected to finned heat exchanger 50. The vapor-phase enthalpy-increasing port 43 of flash evaporator 40 is connected to the intermediate-pressure chamber of compressor 10 via auxiliary gas valve 70. The liquid-phase enthalpy-increasing port 44 of flash evaporator 40 is connected to the intermediate-pressure chamber of compressor 10 via auxiliary liquid valve 80; and the auxiliary gas valve 70 and auxiliary liquid valve 80 are connected in parallel.

[0060] The structure of the flash evaporator 40 with four interfaces and the dual parallel jet circuit enables the heat pump system to achieve independent control and flexible ratio of gaseous and liquid refrigerants, thereby improving the energy efficiency ratio and reliability of the heat pump system under complex operating conditions, extending its service life, and reducing operating costs.

[0061] Furthermore, the heat pump system also includes a capillary tube 90, one end of which is connected to the outlet of the liquid circuit auxiliary valve 80, and the other end is connected to the intermediate pressure chamber of the compressor 10. The capillary tube 90 is also connected in parallel with the gas circuit auxiliary valve 70. When the liquid circuit auxiliary valve 80 is open, the capillary tube 90 provides an auxiliary throttling function, making the liquid refrigerant injection more stable, avoiding the impact of liquid flow fluctuations on the intermediate pressure chamber of the compressor 10, and improving the operational stability of the heat pump system.

[0062] In some alternative embodiments, the heat pump system may also add a capillary tube 90 at the main outlet 42 of the flash evaporator 40 and the inlet end of the finned heat exchanger 50 to achieve the effect of throttling and pressure reduction.

[0063] For example, in this embodiment, the pneumatic auxiliary valve 70, the hydraulic auxiliary valve 80, and the main valve 60 are preferably electronic expansion valves to achieve precise adjustment of the opening degree and rapid response.

[0064] Obviously, the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

[0065] Note that in the description of this specification, the references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A method for controlling the vapor injection enthalpy increase in a heat pump system, characterized in that, Includes the following steps: S1. Collect the ambient temperature Tw of the heat pump system and the outlet water temperature Tout of the plate heat exchanger; S2. Based on the ambient temperature Tw and the outlet water temperature Tout, determine and switch between pure gas injection mode, pure liquid injection mode, or gas-liquid mixed injection mode. S3. Execute the control logic corresponding to the selected injection mode: The flow rates of the gas jet and liquid injection into the intermediate-pressure chamber of the compressor are controlled by independently or in tandem adjustment of the auxiliary valves in the gas and liquid circuits.

2. The heat pump system vapor injection enthalpy control method according to claim 1, characterized in that, In step S2, the trigger condition for the pure gas injection mode is: When the ambient temperature Tw is lower than the first preset temperature and the outlet water temperature Tout is lower than the second preset temperature, the liquid auxiliary valve is closed, and the jet flow rate is adjusted only through the gas auxiliary valve.

3. The heat pump system vapor injection enthalpy control method according to claim 2, characterized in that, In pure gas injection mode, the target superheat is set based on the exhaust temperature and compressor operating frequency. The opening of the auxiliary valve in the gas path is adjusted according to the difference between the actual superheat and the target superheat.

4. The heat pump system vapor injection enthalpy control method according to claim 3, characterized in that, In pure gas injection mode, the opening adjustment of the auxiliary gas valve includes: Calculate the current opening degree of the auxiliary valve in the gas path: Pn = Pn-1 + ΔU; ΔU = Kp × e(t); Among them, P n-1 ΔU is the previous opening degree of the auxiliary valve in the gas path; e(t) is the difference between the actual superheat and the target superheat; and Kp is the proportional coefficient. Actual superheat = exhaust temperature Td - outlet water temperature Tout.

5. The heat pump system vapor injection enthalpy control method according to claim 1, characterized in that, In step S2, the trigger condition for the pure liquid injection mode is: When the ambient temperature Tw is lower than the first preset temperature and the outlet water temperature Tout is higher than the third preset temperature, the gas circuit auxiliary valve is closed, and the liquid flow rate is adjusted only through the liquid circuit auxiliary valve.

6. The heat pump system vapor injection enthalpy control method according to claim 5, characterized in that, In pure liquid injection mode, the opening ratio K_liquid of the auxiliary valve in the liquid circuit is linearly adjusted according to the exhaust temperature Td: K_liquid = A × (Td - B); Where A and B are preset coefficients, the opening ratio K_liquid of the liquid circuit auxiliary valve is positively correlated with the compressor discharge temperature Td, so as to utilize the latent heat of vaporization of the liquid refrigerant to cool the compressor.

7. The heat pump system vapor injection enthalpy control method according to claim 5, characterized in that, The current opening degree of the auxiliary valve in the hydraulic circuit is the product of the opening ratio K_liquid of the auxiliary valve in the hydraulic circuit and the maximum opening degree Pmax of the auxiliary valve in the hydraulic circuit; and the current opening degree of the auxiliary valve in the hydraulic circuit is set between 60 steps and 500 steps.

8. The method for controlling the vapor injection enthalpy increase in a heat pump system according to claim 1, characterized in that, In step S2, the triggering condition for the gas-liquid mixture injection mode is: When the ambient temperature Tw is between the first preset temperature and the fourth preset temperature, or the outlet water temperature Tout is between the second preset temperature and the third preset temperature, the gas circuit auxiliary valve and the liquid circuit auxiliary valve are opened simultaneously.

9. The heat pump system vapor injection enthalpy control method according to claim 8, characterized in that, In the gas-liquid mixed injection mode, the adjustment of the gas-liquid injection ratio includes: When the exhaust temperature Td is lower than the first exhaust threshold, the opening of the gas path auxiliary valve is greater than the opening of the liquid path auxiliary valve, with jet injection as the main method of increasing enthalpy and a small amount of liquid injection as an auxiliary method of cooling. When the exhaust temperature Td is between the first exhaust threshold and the second exhaust threshold, the opening of the gas circuit auxiliary valve is equal to the opening of the liquid circuit auxiliary valve, and the gas-liquid injection is balanced. When the exhaust temperature Td is higher than the second exhaust threshold, the opening of the gas path auxiliary valve is less than the opening of the liquid path auxiliary valve, and the cooling is mainly achieved by liquid injection, with a small amount of air injection to maintain the enthalpy increase.

10. A heat pump system, characterized in that, The heat pump system operates using the heat pump system vapor injection enthalpy control method according to any one of claims 1-9; the heat pump system includes a compressor, a four-way valve, a plate heat exchanger, a flash evaporator, a finned heat exchanger, a main valve, a gas path auxiliary valve, and a liquid path auxiliary valve; The flash evaporator is equipped with a main inlet, a main outlet, a gas phase enthalpy increase port, and a liquid phase enthalpy increase port; The compressor has a medium-pressure chamber, the compressor's exhaust port is connected to the first port of the four-way valve, the second port of the four-way valve is connected to the plate heat exchanger, the third port of the four-way valve is connected to the finned heat exchanger, and the fourth port of the four-way valve is connected to the compressor's intake port. The plate heat exchanger is connected to the main inlet of the flash evaporator through the main valve, and the main outlet of the flash evaporator is connected to the finned heat exchanger. The vapor phase enthalpy-increasing port of the flash evaporator is connected to the medium-pressure chamber of the compressor through the gas path auxiliary valve; The liquid phase enthalpy-increasing port of the flash evaporator is connected to the medium-pressure chamber of the compressor through the liquid circuit auxiliary valve; and the gas circuit auxiliary valve and the liquid circuit auxiliary valve are arranged in parallel.

11. The heat pump system according to claim 10, characterized in that, The heat pump system also includes a capillary tube, one end of which is connected to the outlet of the liquid circuit auxiliary valve and the other end of which is connected to the medium-pressure chamber of the compressor. The capillary tube and the gas circuit auxiliary valve are arranged in parallel.

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