Energy storage air conditioner with automatic liquid injection function and control method thereof

Abstract

The present application relates to the technical field of energy storage air conditioner, in particular to an energy storage air conditioner with automatic liquid injection function and a control method thereof. The energy storage air conditioner comprises an evaporator, an automatic liquid injection path and a control system. The evaporator carries a cold carrier. The automatic liquid injection path is connected with the evaporator. The automatic liquid injection path comprises an inlet pipeline, one end of which is connected with the evaporator and the other end of which is provided with an inlet opening. The inlet pipeline is provided with a circulating pump and an exhaust member. The automatic liquid injection path also comprises an outlet pipeline, one end of which is connected with the evaporator and the other end of which is provided with an outlet opening. The automatic liquid injection path further comprises a liquid supplement pipeline, one end of which is connected with the circulating pump and the other end of which is provided with a liquid supplement opening. The liquid supplement pipeline is provided with an inlet valve. The control system is in communication connection with the automatic liquid injection path. The control system is used to control the start and stop of the automatic liquid injection path according to the first inlet water pressure of the inlet opening and the first outlet water pressure of the outlet opening. A control method for automatic liquid injection is provided. The automation of the liquid injection process is realized. The liquid injection efficiency and accuracy are improved. The stability and reliability of the system are enhanced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of energy storage air conditioners, in particular to an energy storage air conditioner with an automatic liquid injection function and a control method thereof. BACKGROUND

[0002] With the increasing demand for energy and growing concern for environmental issues, the application of energy storage technology in the field of air conditioners is increasingly valued. The energy storage air conditioners on the market require multiple manual operations to open the ball valve and water supplement pump, and multiple manual operations to close the ball valve and water supplement pump after liquid injection. The water pressure in the cooling liquid circulation system needs to be detected to reach the target water pressure. Obviously, repeated manual operations are required to make the circulation system reach the target water pressure for liquid injection. The manual operation steps are complex, prone to errors and low in work efficiency. SUMMARY

[0003] The problem solved by the application is the complicated manual operation and low liquid injection efficiency of the energy storage air conditioner.

[0004] To solve the above problems, the application adopts the following technical scheme: an energy storage air conditioner with an automatic liquid injection function, the energy storage air conditioner comprising: an evaporator, an automatic liquid injection path and a control system, the evaporator carrying a cold carrier, the automatic liquid injection path being connected with the evaporator, the automatic liquid injection path comprising: a liquid inlet pipeline, one end of which is connected with the evaporator and the other end of which is provided with a liquid inlet, the liquid inlet pipeline being provided with a circulating pump and an exhaust member; a liquid outlet pipeline, one end of which is connected with the evaporator and the other end of which is provided with a liquid outlet; a liquid supplement pipeline, one end of which is connected with the circulating pump and the other end of which is provided with a liquid supplement opening, the liquid supplement pipeline being provided with an inlet valve; and the control system being in communication connection with the automatic liquid injection path, the control system being used for controlling the start and stop of the automatic liquid injection path according to the first water inlet pressure of the liquid inlet and the first water outlet pressure of the liquid outlet.

[0005] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: by arranging the automatic liquid injection path and the control system in communication connection with the automatic liquid injection path, the automation of the liquid injection process of the energy storage air conditioner is realized. Without manual intervention, the start and stop of the liquid injection path can be automatically controlled according to the water inlet pressure of the liquid inlet and the water outlet pressure of the liquid outlet, which greatly improves the liquid injection efficiency and saves the labor cost and time cost. Meanwhile, the circulating pump and the exhaust member are arranged in the liquid inlet pipeline, which reduces the additional liquid injection pump. Only the principle of water pumping by the circulating pump is used. The exhaust member is used to cut off the flow channel in the liquid inlet pipeline to create a site lower than the atmospheric pressure. The site is connected with the external waterway. The external atmospheric pressure presses the water into the pipeline with low air pressure to create negative pressure, realizes the system injection, saves the cost, prevents the adverse effects of gas on the liquid injection process and the system operation, and guarantees the stable operation of the system. Furthermore, all the functions of the circulating pump and the liquid injection pump can be realized by using a single circulating pump, which reduces the cost.

[0006] Further, the liquid supplement pipeline further comprises an inlet liquid one-way valve, the inlet liquid one-way valve is connected with the inlet valve in parallel, one end of the inlet liquid one-way valve is connected with the circulating pump, and the other end is connected with the liquid supplement port.

[0007] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: the inlet liquid one-way valve is added in parallel with the inlet valve in the liquid supplement pipeline, the inlet valve does not need to be opened to realize liquid injection, the reverse flow of the refrigerant under certain conditions can be prevented, the inlet valve and the inlet liquid one-way valve jointly act to further ensure the stable progress of the liquid supplement process, the frequent opening and closing of the liquid supplement port is avoided, the reliability of liquid injection is enhanced, and the liquid injection efficiency is greatly improved.

[0008] Further, the exhaust member adopts a first ball valve, and the pressure difference of the inlet liquid pipeline is controlled by opening and closing the first ball valve.

[0009] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: the pressure difference of the inlet liquid pipeline can be adjusted by accurately controlling the opening and closing of the first ball valve, so that the pressure state in the pipeline can be adjusted according to actual needs during liquid injection, the refrigerant can enter the evaporator at a suitable flow rate and pressure, and the efficiency and accuracy of liquid injection are improved.

[0010] Further, the inlet port and the outlet port are provided with pressure sensors.

[0011] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: the pressure sensors are arranged at the inlet port and the outlet port, the pressures of the inlet liquid and the outlet liquid can be monitored in real time, and the control system adjusts the liquid injection in real time and accurately according to the pressures of the inlet port and the outlet port.

[0012] Further, the liquid supplement pipeline further comprises a liquid supplement device, the liquid supplement device is connected with the inlet valve, and the control system is further used for controlling the start and stop of the automatic liquid injection path according to the liquid level information in the liquid supplement device and the first inlet water pressure of the inlet port and the first outlet water pressure of the outlet port.

[0013] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: the liquid supplement device is added, and the start and stop of the automatic liquid injection path are controlled by the control system according to the liquid level information in the liquid supplement device and the pressures of the inlet port and the outlet port, so that the liquid injection control is more accurate, the combination of the liquid level information and the pressure information can comprehensively reflect the state of the refrigerant in the energy storage air conditioning system, and the stability of the liquid injection is ensured, and the situations of insufficient liquid injection or excessive liquid injection are avoided.

[0014] The second object of the present application is to provide an automatic liquid injection control method applied to the energy storage air conditioner, the automatic liquid injection control method comprising: obtaining the inlet water pressure and the outlet water pressure, obtaining the circulating pump operating frequency; comparing the inlet water pressure with the preset water pressure maximum value, comparing the inlet water pressure with the preset water pressure minimum value; comparing the outlet water pressure with the preset water pressure maximum value, comparing the outlet water pressure with the preset water pressure minimum value; when the preset water pressure minimum value is greater than or equal to the inlet water pressure and the preset water pressure minimum value is greater than or equal to the outlet water pressure, step A is executed;

[0015] Step A, determining whether the circulating pump operating frequency is the preset maximum operating frequency, if yes, the energy storage air conditioner completes liquid injection.

[0016] Compared with the prior art, the technical effects achieved by adopting the technical scheme are: the control method realizes intelligent control of the liquid injection process of the energy storage air conditioner by obtaining the inlet water pressure and the outlet water pressure and the circulating pump operating frequency. The liquid injection state can be automatically judged according to real-time pressure and frequency parameters, without manual intervention, thereby improving the accuracy and efficiency of liquid injection. The inlet water pressure and the outlet water pressure are controlled within the above range to prevent overpressure damage to the air conditioner evaporator and its pipeline.

[0017] Further, after obtaining the inlet water pressure and the outlet water pressure and the circulating pump operating frequency, the automatic liquid injection control method further comprises: closing the exhaust member and starting the circulating pump, and executing step B;

[0018] Step B, the circulating pump load is b*Ki (i=1, 2, 3, 4, …, i, i+1), wherein 0≤Ki≤100%, and b is the preset maximum operating frequency.

[0019] Compared with the prior art, the technical effects achieved by adopting the technical scheme are: the required pressure of the energy storage air conditioner is the basis for the circulation of the circulating pump. If the circulating pump load is less than the required pressure of the energy storage air conditioner, liquid cannot be supplemented. At the same time, the required pressure of the energy storage air conditioner is less than or equal to the pipeline design pressure. During the liquid supplementing process, the circulating pump load is continuously increased, which can effectively reduce the entry of air and ensure that the load coolant can be smoothly injected into the system.

[0020] Further, step A further comprises determining whether the circulating pump operating frequency is the preset maximum operating frequency, if no, step E is entered,

[0021] Step E comprises: increasing the circulating pump load, wherein K(i+1)=Ki+J, J>0, determining whether K(i+1) is less than 100%, if yes, the circulating pump load is b*K(i+1), if no, the circulating pump operating frequency is 100%.

[0022] Compared with the prior art, the technical effects achieved by adopting the technical scheme are: gradually increasing the water pump frequency, if the water pressure under different water pump frequencies can meet the system design requirements, it indicates that the gas has been basically discharged, if the water pressure does not meet the requirements during the process of increasing the water pump frequency, it indicates that the existing air has been discharged and needs to be recharged. Precise control of the circulating pump load can reduce the unstable outlet pressure caused by air during the liquid injection process, so as to improve the efficiency and accuracy of liquid injection.

[0023] Further, step B further comprises: detecting the outlet water pressure and the liquid injection pressure, and when the outlet water pressure is greater than or equal to the liquid injection pressure, the liquid injection path automatically enters the air exhaust mode.

[0024] Compared with the prior art, the technical effects achieved by adopting the technical scheme are: when the outlet water pressure is greater than or equal to the liquid injection pressure, it indicates that there is air in the pipeline, and the air in the pipeline needs to be discharged in the air exhaust mode.

[0025] Further, the air exhaust mode comprises: step C, closing the circulating pump and opening the air exhaust member, and executing step D.

[0026] Step D, opening the circulating pump, judging whether the running time of the circulating pump this time is greater than or equal to the preset time, and whether the preset water pressure minimum value is greater than or equal to the inlet water pressure and the outlet water pressure, if yes, entering step A.

[0027] Compared with the prior art, the technical effects achieved by adopting the technical scheme are: during the liquid injection process, the existence of air will seriously affect the accuracy and stability of liquid injection. The air exhaust mode can effectively discharge the air in time, ensure that the refrigerant can fill the pipeline, thereby ensuring the accuracy of liquid injection, and enabling the energy storage air conditioning system to operate normally and achieve the best performance. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 FIG. 1 is a structural schematic diagram of an energy storage air conditioner according to an embodiment of the present application;

[0029] Figure 2 FIG. 2 is a flow chart of an automatic liquid injection control method of an energy storage air conditioner according to an embodiment of the present application.

[0030] Mark 100- energy storage air conditioner, 1- evaporator; 2- air exhaust member; 3- circulating pump; 4- liquid inlet check valve; 5- liquid inlet valve, 6- liquid inlet, 7- liquid outlet, 8- liquid supplement port. DETAILED DESCRIPTION

[0031] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings.

[0032] Reference Figures 1-2The application provides a storage energy air conditioner 100 with an automatic liquid injection function, and the storage energy air conditioner 100 comprises an evaporator 1, an automatic liquid injection path and a control system, the evaporator 1 carries a cold carrier, the automatic liquid injection path is connected with the evaporator 1, and the automatic liquid injection path comprises an inlet liquid pipeline, an outlet liquid pipeline and a liquid supplement pipeline, one end of the inlet liquid pipeline is connected with the evaporator 1, the other end is provided with an inlet opening 6, and a circulating pump 3 and an exhaust member 2 are arranged at the inlet liquid pipeline; one end of the outlet liquid pipeline is connected with the evaporator 1, and the other end is provided with an outlet opening 7; one end of the liquid supplement pipeline is connected with the circulating pump 3, the other end is provided with a liquid supplement opening 8, and an inlet valve 5 is arranged at the liquid supplement pipeline; the control system is in communication connection with the automatic liquid injection path, and the control system is used for controlling the start and stop of the automatic liquid injection path according to a first water inlet pressure of the inlet opening 6 and a first water outlet pressure of the outlet opening 7.

[0033] By arranging the automatic liquid injection path and the control system in communication connection with the automatic liquid injection path, the automation of the liquid injection process of the storage energy air conditioner 100 is realized. The start and stop of the liquid injection path can be automatically controlled according to the water inlet pressure of the inlet opening 6 and the water outlet pressure of the outlet opening 7 without manual intervention, the liquid injection efficiency is greatly improved, and the labor cost and time cost are saved. Meanwhile, the circulating pump 3 and the exhaust member 2 are arranged at the inlet liquid pipeline, the additional liquid injection pump is reduced, only the principle of water pumping by the circulating pump 3 is used, the exhaust member 2 is used to cut off the flow channel in the inlet liquid pipeline, a site lower than the atmospheric pressure is created, the site is connected with the external waterway, the external atmospheric pressure presses the water into the pipeline with low air pressure, the negative pressure is created, the system is filled, the cost is saved, the adverse effects of the gas on the liquid injection process and the system operation are prevented, the stable operation of the system is ensured, furthermore, all the functions of the circulating pump 3 and the liquid injection pump can be realized by using a single circulating pump 3, and the cost is reduced.

[0034] Specifically, referring to Figure 1 The liquid supplement pipeline further comprises an inlet one-way valve 4, the inlet one-way valve 4 is connected in parallel with the inlet valve 5, one end of the inlet one-way valve 4 is connected with the circulating pump 3, and the other end is connected with the liquid supplement opening 8.

[0035] Meanwhile, by way of example, the inlet one-way valve can be arranged in multiple numbers according to the system requirement.

[0036] The inlet one-way valve 4 is arranged in parallel with the inlet valve 5 in the liquid supplement pipeline, the inlet valve 5 does not need to be opened to realize the liquid injection, the reverse flow of the cold carrier under specific conditions can be prevented, the inlet valve 5 cooperates with the inlet one-way valve 5 to further ensure the stable implementation of the liquid supplement process, and the frequent opening and closing of the liquid supplement opening 8 can be avoided, the reliability of the liquid injection is enhanced, and the liquid injection efficiency is greatly improved.

[0037] Further, the exhaust member 2 adopts a first ball valve, and the pressure difference of the inlet liquid pipeline is controlled by the opening and closing of the first ball valve.

[0038] For example, the first ball valve adopts an electric ball valve, which can save costs and adjust the pressure difference of the liquid inlet pipeline by precisely controlling the opening and closing of the first ball valve. This enables the pressure in the pipeline to be adjusted according to actual needs during the liquid injection process, ensuring that the refrigerant can enter the evaporator 1 at an appropriate flow rate and pressure, thereby improving the efficiency and accuracy of liquid injection.

[0039] Further, the liquid inlet 6 and the liquid outlet 7 are provided with pressure sensors.

[0040] The liquid inlet 6 and the liquid outlet 7 are provided with pressure sensors, which can monitor the pressure of the liquid inlet and the liquid outlet in real time. The control system adjusts the liquid injection in real time and accurately according to the pressure of the liquid inlet 6 and the liquid outlet 7.

[0041] Further, the liquid supplement pipeline further comprises a liquid supplement device connected to the liquid inlet valve 5, and the control system is further configured to control the start and stop of the automatic liquid injection pipeline according to the liquid level information in the liquid supplement device and the first water inlet pressure of the liquid inlet 6 and the first water outlet pressure of the liquid outlet 7.

[0042] The addition of the liquid supplement device and the control of the start and stop of the automatic liquid injection pipeline by the control system according to the liquid level information in the liquid supplement device and the pressure of the liquid inlet 6 and the liquid outlet 7 makes the liquid injection control more accurate. The combination of liquid level information and pressure information can comprehensively reflect the state of the refrigerant in the energy storage air conditioner 100 system, thereby ensuring the stability of the liquid injection and avoiding the occurrence of insufficient or excessive liquid injection.

[0043] The second object of the present application is to provide an automatic liquid injection control method applied to the above-mentioned energy storage air conditioner 100, as shown in Figure 2 The automatic liquid injection control method comprises: obtaining the water inlet pressure and the water outlet pressure, obtaining the running frequency of the circulating pump 3; comparing the water inlet pressure with the preset water pressure maximum value and the preset water pressure minimum value; comparing the water outlet pressure with the preset water pressure maximum value and the preset water pressure minimum value; when the preset water pressure minimum value is greater than or equal to the water inlet pressure and the preset water pressure minimum value is greater than or equal to the water outlet pressure, step A is executed.

[0044] Step A, determining whether the running frequency of the circulating pump 3 is the preset maximum running frequency, if yes, the energy storage air conditioner 100 completes the liquid injection.

[0045] The control method realizes intelligent control of the liquid injection process of the energy storage air conditioner 100 by obtaining the water inlet pressure and the water outlet pressure and the running frequency of the circulating pump 3. According to the real-time pressure and frequency parameters, the liquid injection state can be automatically judged without manual intervention, thereby improving the accuracy and efficiency of liquid injection. The water inlet pressure and the water outlet pressure are controlled within the above-mentioned range to prevent overpressure damage to the air conditioner evaporator 1 and its pipeline.

[0046] It is to be noted that the control method is initiated according to the demand of the energy storage air conditioner 1, and performs corresponding actions. The initial state of the inlet valve 5 is closed, and the liquid supplementing operation is performed by installing a liquid supplementing tank.

[0047] When the circulating pump 3 is running, a certain time is needed to wait for the gas to be discharged to the maximum extent. At this time, due to the running of the water pump, the water flow impact, and the water pressure fluctuation, or due to the gas existing in the pipeline, if the inlet water pressure and the outlet water pressure meet the above condition interval, it is indicated that the gas has been basically discharged or meets the system design operation requirement at the frequency of the water pump. If the above interval is not met, it is indicated that the water quantity cannot meet the design requirement of the energy storage air conditioner.

[0048] Further, after obtaining the inlet water pressure and the outlet water pressure and obtaining the running frequency of the circulating pump 3, the automatic liquid injection control method further comprises: closing the exhaust member 2, and starting the circulating pump 3 to perform step B.

[0049] In step B, the load of the circulating pump 3 is b*Ki (i=1, 2, 3, 4, …, i, i+1), wherein 0≤Ki≤100%, and b is the preset highest running frequency.

[0050] The required pressure of the energy storage air conditioner 100 is the basis for the circulation of the circulating pump 3. If the load of the circulating pump 3 is less than the required pressure of the energy storage air conditioner 100, the liquid supplementing cannot be performed. Meanwhile, the required pressure of the energy storage air conditioner 100 is less than or equal to the design pressure of the pipeline. During the liquid supplementing process, the load of the circulating pump 3 is continuously increased, which can effectively reduce the air entering and ensure that the refrigerant can be smoothly injected into the system. It is to be noted that the low load initial running of the circulating pump 3 is more beneficial to the gas discharge and improves the stability of the liquid supplementing.

[0051] Specifically, step A further comprises judging whether the running frequency of the circulating pump 3 is the preset highest running frequency. If not, step E is entered.

[0052] Step E comprises: increasing the load of the circulating pump 3, wherein K(i+1)=Ki+J, J>0, judging whether K(i+1) is less than 100%. If yes, the load of the circulating pump 3 is b*K(i+1). If not, the running frequency of the circulating pump 3 is 100%.

[0053] The frequency of the circulating pump 3 is gradually increased. If the water pressure under different frequencies of the circulating pump 3 can meet the system design requirement, it is indicated that the gas has been basically discharged. If the water pressure does not meet the requirement during the process of increasing the frequency of the circulating pump 3, it is indicated that the existing air has been discharged and needs to be supplemented again. Precise control of the load of the circulating pump 3 can reduce the unstable pressure of the outlet 7 during the liquid supplementing process caused by the air, so as to improve the efficiency and accuracy of the liquid supplementing.

[0054] Specifically, step B further comprises: detecting the outlet water pressure and the liquid supplementing pressure. When the outlet water pressure≥the liquid supplementing pressure, the automatic liquid injection path enters the exhaust mode.

[0055] When the outlet water pressure is greater than or equal to the liquid injection pressure, it indicates that there is air in the pipeline, and the air in the pipeline needs to be discharged in the air discharge mode.

[0056] Further, referring to Figure 2 , the air discharge mode comprises: step C, closing the circulating pump 3, opening the air discharge member 2, and performing step D;

[0057] Step D, opening the circulating pump 3, judging whether the running time of the circulating pump 3 is greater than or equal to the preset time, and whether the preset minimum water pressure is greater than or equal to the inlet water pressure, and whether the preset minimum water pressure is greater than or equal to the outlet water pressure, if yes, entering step A.

[0058] During the liquid injection process, the existence of air can seriously affect the accuracy and stability of the liquid injection. The air discharge mode can effectively discharge the air in time, ensure that the load-carrying agent can fill the pipeline, thereby ensuring the accuracy of the liquid injection, enabling the energy storage air conditioner 100 system to operate normally and play the best performance.

[0059] Although the present application is disclosed as above, the present application is not limited to this. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and therefore the protection scope of the present application should be subject to the scope defined by the claims.

Claims

1. An automatic liquid injection control method characterized by comprising: The method is applied to a stored energy air conditioner (100) comprising an evaporator (1) carrying a cold carrier, an automatic liquid injection path connected with the evaporator (1), and a control system, wherein the automatic liquid injection path comprises: an inlet pipe connected with the evaporator (1) at one end and provided with an inlet (6) at the other end, the inlet pipe being provided with a circulating pump (3) and an exhaust member (2); an outlet pipe connected with the evaporator (1) at one end and provided with an outlet (7) at the other end; a liquid supplement pipe connected with the circulating pump (3) at one end and provided with a liquid supplement port (8) at the other end, the liquid supplement pipe being provided with an inlet valve (5); the control system is in communication connection with the automatic liquid injection path, and is used for controlling start and stop of the automatic liquid injection path according to a first water inlet pressure of the inlet (6) and a first water outlet pressure of the outlet (7); the automatic liquid injection control method comprises: acquiring water inlet pressure and water outlet pressure, and acquiring a running frequency of the circulating pump (3); comparing the water inlet pressure with a preset water pressure maximum value and a preset water pressure minimum value; comparing the water outlet pressure with the preset water pressure maximum value and the preset water pressure minimum value; when the preset water pressure minimum value is greater than or equal to the water inlet pressure and greater than or equal to the preset water pressure minimum value, and the preset water pressure minimum value is greater than or equal to the water outlet pressure and greater than or equal to the preset water pressure minimum value, step A is executed; step A: judging whether the running frequency of the circulating pump (3) is a preset maximum running frequency, if yes, the stored energy air conditioner (100) is completed with liquid injection.

2. The automatic liquid injection control method according to claim 1, wherein The liquid supplement pipe further comprises an inlet one-way valve (4) connected with the inlet valve (5) in parallel, one end of the inlet one-way valve (4) being connected with the circulating pump (3) and the other end being connected with the liquid supplement port (8).

3. The automatic liquid injection control method according to claim 2, wherein The exhaust member (2) is a first ball valve, and the pressure difference of the inlet pipe is controlled by opening and closing of the first ball valve.

4. The automatic liquid injection control method according to claim 1, wherein The inlet (6) and the outlet (7) are provided with pressure sensors.

5. The automatic liquid injection control method according to claim 1, wherein The liquid supplement pipe further comprises a liquid supplement device connected with the inlet valve (5), and the control system is further used for controlling start and stop of the automatic liquid injection path according to liquid level information in the liquid supplement device and water inlet pressure of the inlet (6) and water outlet pressure of the outlet (7).

6. The automatic liquid injection control method according to claim 1, wherein After the acquisition of the water inlet pressure and the water outlet pressure and the acquisition of the running frequency of the circulating pump (3), the automatic liquid injection control method further comprises: closing the exhaust member (2) and starting the circulating pump (3), and executing step B; Step B, the circulating pump (3) load is b Ki (i = 1, 2, 3, 4, …, i, i+1), wherein, 0≤Ki≤100%, b is the preset maximum operating frequency.

7. The automatic liquid injection control method according to claim 1, wherein Step A further comprises judging whether the running frequency of the circulating pump (3) is a preset maximum running frequency, if no, step E is entered, and step E comprises: increasing the load of the circulating pump (3), wherein K(i+1)=Ki+J, J>0, judging whether K(i+1) is less than 100%, if yes, the load of the circulating pump (3) is b K(i+1), if no, the running frequency of the circulating pump (3) is 100%.

8. The automatic liquid injection control method according to claim 6, wherein Step B further comprises: detecting the water outlet pressure and the liquid injection pressure, and when the water outlet pressure is greater than or equal to the liquid injection pressure, the automatic liquid injection path enters an exhaust mode.

9. The automatic liquid injection control method according to claim 8, wherein The exhaust mode comprises: Step C: closing the circulating pump (3) and opening the exhaust member (2), and executing step D; Step D, open the circulating pump (3), determine whether the circulating pump (3) this running time is greater than or equal to the preset time, and the preset water pressure minimum value ≥ the water inlet pressure ≥ the preset water pressure minimum value, and the preset water pressure minimum value ≥ the water outlet pressure ≥ the preset water pressure minimum value, if yes, enter step A.

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