阅读说明：本技术 一种制冷系统和两级节流阀的控制方法 (Refrigerating system and control method of two-stage throttle valve ) 是由 程振军 李根源 徐晓明 禹志强 王军骅 于小杰 于 2020-12-23 设计创作，主要内容包括：本发明公开了一种制冷系统和两级节流阀的控制方法,该制冷系统包括,压缩机,经济器,用于将气态和液态冷媒分离,气态冷媒沿补气管道进入所述压缩机,液态冷媒进入蒸发器内；一级节流阀,设置于所述冷凝器与所述经济器之间,用于对冷媒进行节流；二级节流阀,设置于所述经济器与所述蒸发器之间,用于对冷媒进行节流；控制器,被配置为：获取所述经济器的液位高度和所述蒸发器的液位高度；基于所述经济器的液位高度、所述蒸发器的液位高度以及蒸发器目标液位高度控制所述一级节流阀与所述二级节流阀的开度,从而实现两级节流阀的协调控制,有效减少了吸气带液和补气带液的风险。(The invention discloses a refrigeration system and a control method of a two-stage throttle valve, wherein the refrigeration system comprises a compressor and an economizer, wherein the economizer is used for separating gaseous refrigerant from liquid refrigerant; the primary throttle valve is arranged between the condenser and the economizer and used for throttling the refrigerant; the secondary throttle valve is arranged between the economizer and the evaporator and used for throttling the refrigerant; a controller configured to: acquiring the liquid level height of the economizer and the liquid level height of the evaporator; and the opening degree of the first-stage throttling valve and the opening degree of the second-stage throttling valve are controlled based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator, so that the coordinated control of the two-stage throttling valves is realized, and the risks of air suction liquid entrainment and air supply liquid entrainment are effectively reduced.)

1. A refrigeration system, comprising:

the compressor is used for compressing low-temperature and low-pressure refrigerant gas into high-temperature and high-pressure refrigerant gas and discharging the high-temperature and high-pressure refrigerant gas to the condenser;

the economizer is used for separating gas refrigerant from liquid refrigerant, the gas refrigerant enters the compressor along the air supply pipeline, and the liquid refrigerant enters the evaporator;

the primary throttle valve is arranged between the condenser and the economizer and used for throttling the refrigerant;

the secondary throttle valve is arranged between the economizer and the evaporator and used for throttling the refrigerant;

a controller configured to:

acquiring the liquid level height of the economizer and the liquid level height of the evaporator;

controlling the opening of the primary throttle valve and the secondary throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and an evaporator target liquid level height.

2. The refrigerant system as set forth in claim 1, wherein said controller is further configured to:

when the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, reducing the opening of the secondary throttle valve;

and when the liquid level height of the evaporator is smaller than the target liquid level height of the evaporator, increasing the opening degree of the secondary throttle valve.

3. The refrigerant system as set forth in claim 2, wherein said controller is further configured to:

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttle valve is increased, the opening of the primary throttle valve is increased;

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttling valve is reduced, the opening of the primary throttling valve is reduced;

the negative deviation liquid level height is the difference between the economizer target liquid level height and a preset deviation height, and the positive deviation liquid level height is the sum of the economizer target liquid level height and the preset deviation height.

4. The refrigerant system as set forth in claim 3, wherein said controller is further configured to:

when the liquid level height of the economizer is greater than or equal to a preset liquid level lower limit height and smaller than the negative deviation liquid level height, if the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, the opening degree of the primary throttling valve is kept;

and when the liquid level height of the economizer is greater than or equal to the preset liquid level lower limit height and smaller than the negative deviation liquid level height, if the liquid level height of the evaporator is less than or equal to the target liquid level height of the evaporator, increasing the opening degree of the primary throttle valve to a first preset opening degree.

5. The refrigerant system as set forth in claim 3, wherein said controller is further configured to:

when the liquid level height of the economizer is greater than or equal to the positive deviation liquid level height and less than or equal to a preset liquid level upper limit height, if the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, reducing the opening degree of the primary throttle valve to a fourth preset opening degree;

and when the liquid level height of the economizer is greater than or equal to the positive deviation liquid level height and less than or equal to the preset liquid level upper limit height, if the liquid level height of the evaporator is less than or equal to the evaporator target liquid level height, the opening degree of the primary throttle valve is maintained.

6. The refrigerant system as set forth in claim 1, wherein said controller is further configured to:

when the liquid level height of the economizer is smaller than or equal to a preset liquid level lower limit height and the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, increasing the opening degree of the primary throttle valve to the first preset opening degree;

and when the liquid level height of the economizer is smaller than or equal to the preset liquid level lower limit height and the liquid level height of the evaporator is smaller than or equal to the target liquid level height of the evaporator, increasing the opening degree of the primary throttle valve to a second preset opening degree.

7. The refrigerant system as set forth in claim 1, wherein said controller is further configured to:

when the liquid level height of the economizer is larger than the preset upper liquid level limit height and the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, reducing the opening degree of the primary throttle valve to a third preset opening degree;

and when the liquid level height of the economizer is larger than the preset upper liquid level limit height and the liquid level height of the evaporator is smaller than or equal to the target liquid level height of the evaporator, reducing the opening degree of the primary throttle valve to a fourth preset opening degree.

8. A control method of a two-stage throttle valve is applied to a refrigeration system including a compressor, an economizer, a one-stage throttle valve, a two-stage throttle valve, and a controller,

the first-stage throttling valve is arranged between the condenser and the economizer, and the second-stage throttling valve is arranged between the economizer and the evaporator;

the method comprises the following steps:

acquiring the liquid level height of the economizer and the liquid level height of the evaporator;

controlling the opening of the primary throttle valve and the secondary throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and an evaporator target liquid level height.

9. The control method of claim 8, wherein the opening of the primary throttle valve and the secondary throttle valve is controlled based on the economizer liquid level height, the evaporator liquid level height, and an evaporator target liquid level height, in particular:

when the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, reducing the opening of the secondary throttle valve;

and when the liquid level height of the evaporator is smaller than the target liquid level height of the evaporator, increasing the opening degree of the secondary throttle valve.

10. The control method of claim 9, wherein the opening of the primary throttle valve and the secondary throttle valve is controlled based on the economizer liquid level height, the evaporator liquid level height, and an evaporator target liquid level height, in particular:

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttle valve is increased, the opening of the primary throttle valve is increased;

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttling valve is reduced, the opening of the primary throttling valve is reduced;

the negative deviation liquid level height is the difference between the economizer target liquid level height and a preset deviation height, and the positive deviation liquid level height is the sum of the economizer target liquid level height and the preset deviation height.

Technical Field

The present application relates to the field of refrigeration system control, and more particularly, to a refrigeration system and a method of controlling a two-stage throttle valve.

Background

A refrigeration system is a device that cools or heats a room by using a refrigeration cycle of a refrigerant, and the refrigerant is sequentially compressed, condensed, expanded, and evaporated, and performs a cooling or heating function by using a characteristic that the refrigerant absorbs ambient heat when vaporized and emits the heat when liquefied.

In a refrigeration cycle system of a refrigeration system, a two-stage throttling and middle air-replenishing refrigeration cycle is often used, the control of a two-stage throttling device is often based on respective independent control targets, and because of the different control targets, the system is often large in fluctuation and difficult to stabilize, the actual operation energy efficiency of a unit is also low, and even the unit is seriously abnormal, such as air suction liquid entrainment or air replenishing liquid entrainment.

Therefore, how to make the operation of the refrigerating system unit more stable and effectively reduce the risks of air suction liquid entrainment and air supply liquid entrainment is a technical problem to be solved at present.

Disclosure of Invention

The invention provides a refrigerating system for solving the technical problem that the risk of air suction liquid entrainment and air supply liquid entrainment can not be effectively reduced in the prior art, comprising:

the compressor is used for compressing low-temperature and low-pressure refrigerant gas into high-temperature and high-pressure refrigerant gas and discharging the high-temperature and high-pressure refrigerant gas to the condenser;

the economizer is used for separating gas refrigerant from liquid refrigerant, the gas refrigerant enters the compressor along the air supply pipeline, and the liquid refrigerant enters the evaporator;

the primary throttle valve is arranged between the condenser and the economizer and used for throttling the refrigerant;

the secondary throttle valve is arranged between the economizer and the evaporator and used for throttling the refrigerant;

a controller configured to:

acquiring the liquid level height of the economizer and the liquid level height of the evaporator;

controlling the opening of the primary throttle valve and the secondary throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and an evaporator target liquid level height.

In some embodiments, the controller is further configured to:

when the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, reducing the opening of the secondary throttle valve;

and when the liquid level height of the evaporator is smaller than the target liquid level height of the evaporator, increasing the opening degree of the secondary throttle valve.

In some embodiments, the controller is further configured to:

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttle valve is increased, the opening of the primary throttle valve is increased;

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttling valve is reduced, the opening of the primary throttling valve is reduced;

the negative deviation liquid level height is the difference between the economizer target liquid level height and a preset deviation height, and the positive deviation liquid level height is the sum of the economizer target liquid level height and the preset deviation height.

In some embodiments, the controller is further configured to:

when the liquid level height of the economizer is greater than or equal to a preset liquid level lower limit height and smaller than the negative deviation liquid level height, if the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, the opening degree of the primary throttling valve is kept;

and when the liquid level height of the economizer is greater than or equal to the preset liquid level lower limit height and smaller than the negative deviation liquid level height, if the liquid level height of the evaporator is less than or equal to the target liquid level height of the evaporator, increasing the opening degree of the primary throttle valve to a first preset opening degree.

In some embodiments, the controller is further configured to:

when the liquid level height of the economizer is greater than or equal to the positive deviation liquid level height and less than or equal to a preset liquid level upper limit height, if the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, reducing the opening degree of the primary throttle valve to a fourth preset opening degree;

and when the liquid level height of the economizer is greater than or equal to the positive deviation liquid level height and less than or equal to the preset liquid level upper limit height, if the liquid level height of the evaporator is less than or equal to the evaporator target liquid level height, the opening degree of the primary throttle valve is maintained.

In some embodiments, the controller is further configured to:

when the liquid level height of the economizer is smaller than or equal to a preset liquid level lower limit height and the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, increasing the opening degree of the primary throttle valve to the first preset opening degree;

and when the liquid level height of the economizer is smaller than or equal to the preset liquid level lower limit height and the liquid level height of the evaporator is smaller than or equal to the target liquid level height of the evaporator, increasing the opening degree of the primary throttle valve to a second preset opening degree.

In some embodiments, the controller is further configured to:

when the liquid level height of the economizer is larger than the preset upper liquid level limit height and the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, reducing the opening degree of the primary throttle valve to a third preset opening degree;

and when the liquid level height of the economizer is larger than the preset upper liquid level limit height and the liquid level height of the evaporator is smaller than or equal to the target liquid level height of the evaporator, reducing the opening degree of the primary throttle valve to a fourth preset opening degree.

Accordingly, the present invention also provides a control method of a two-stage throttle valve, which is applied to a refrigeration system including a compressor, an economizer, a one-stage throttle valve, a two-stage throttle valve, and a controller, wherein,

the first-stage throttling valve is arranged between the condenser and the economizer, and the second-stage throttling valve is arranged between the economizer and the evaporator;

the method comprises the following steps:

acquiring the liquid level height of the economizer and the liquid level height of the evaporator;

controlling the opening of the primary throttle valve and the secondary throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and an evaporator target liquid level height.

In some embodiments, the controlling the opening of the primary throttle valve and the secondary throttle valve according to the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator comprises:

when the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, reducing the opening of the secondary throttle valve;

and when the liquid level height of the evaporator is smaller than the target liquid level height of the evaporator, increasing the opening degree of the secondary throttle valve.

In some embodiments, the controlling the opening of the primary throttle valve and the secondary throttle valve according to the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator comprises:

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttle valve is increased, the opening of the primary throttle valve is increased;

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttling valve is reduced, the opening of the primary throttling valve is reduced;

the negative deviation liquid level height is the difference between the economizer target liquid level height and a preset deviation height, and the positive deviation liquid level height is the sum of the economizer target liquid level height and the preset deviation height.

Compared with the prior art, the method has the following beneficial effects:

the invention discloses a refrigeration system and a control method of a two-stage throttle valve, wherein the refrigeration system comprises a compressor and an economizer, wherein the economizer is used for separating gaseous refrigerant from liquid refrigerant; the primary throttle valve is arranged between the condenser and the economizer and used for throttling the refrigerant; the secondary throttle valve is arranged between the economizer and the evaporator and used for throttling the refrigerant; a controller configured to: acquiring the liquid level height of the economizer and the liquid level height of the evaporator; the opening degree of the first-stage throttling valve and the opening degree of the second-stage throttling valve are controlled based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator, so that the refrigerating system unit can run more stably, and the risks of air suction liquid entrainment and air supply liquid entrainment are effectively reduced.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic structural diagram of a refrigeration system according to an embodiment of the present application;

fig. 2 is a schematic flow chart of a control method of a two-stage throttle valve according to an embodiment of the present application.

Description of the reference symbols

1. The system comprises a compressor 2, a condenser 3, an evaporator 4, an economizer 5, a primary throttle valve 6 and a secondary throttle valve.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, it is to be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present application.

The terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless otherwise specified.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

In the embodiment of the application, as shown in fig. 1, gaseous refrigerant discharged from the compressor 1 enters the condenser 2, the gaseous refrigerant is condensed into liquid refrigerant in the condenser 2, the liquid refrigerant is throttled by the first-stage throttle valve 5 and then becomes two-phase fluid to enter the economizer 4, in the economizer 4, the gaseous refrigerant is separated from the liquid refrigerant, the gaseous refrigerant enters the intermediate air supplement port of the compressor 1 along the air supplement pipeline, the liquid refrigerant enters the evaporator 3 after being throttled by the second-stage throttle valve 6, the liquid refrigerant is thermally evaporated into gaseous refrigerant in the evaporator 3 and enters the compressor 1 along the air suction pipeline, so that the refrigeration cycle of one-step two-stage throttling and intermediate air supplement is completed.

To further describe aspects of the present application, in one example of the present application, the refrigeration system comprises:

the compressor 1 is used for compressing low-temperature and low-pressure refrigerant gas into high-temperature and high-pressure refrigerant gas and discharging the high-temperature and high-pressure refrigerant gas to the condenser 2;

the economizer 4 is used for separating gas refrigerant from liquid refrigerant, the gas refrigerant enters the compressor 1 along the air supply pipeline, and the liquid refrigerant enters the evaporator 3;

the primary throttle valve 5 is arranged between the condenser 2 and the economizer 4 and used for throttling the refrigerant;

the secondary throttle valve 6 is arranged between the economizer 4 and the evaporator 3 and used for throttling the refrigerant;

a controller configured to:

acquiring the liquid level height of the economizer and the liquid level height of the evaporator;

controlling the opening of the primary throttle valve and the secondary throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and an evaporator target liquid level height.

In this embodiment, the economizer may be a flash tank economizer or other types of economizers, a primary throttle valve is disposed between the condenser and the economizer and used for throttling the refrigerant before entering the economizer, and a secondary throttle valve is disposed between the economizer and the evaporator and used for throttling the refrigerant before entering the evaporator; the controller respectively acquires the liquid level heights of the economizer and the evaporator, and then controls the opening degrees of the primary throttle valve and the secondary throttle valve according to the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator. The target liquid level height of the evaporator is the liquid level height set during the working of the refrigerating system and can be controlled by a user according to the requirement. Optionally, the target evaporator liquid level height may be associated with a set temperature of the refrigeration system, and when a user adjusts the set temperature of the refrigeration system, the target evaporator liquid level height is also adjusted accordingly.

In order to accurately adjust the opening of the two-step throttle valve, in some embodiments, the controller is further configured to:

when the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, reducing the opening of the secondary throttle valve;

and when the liquid level height of the evaporator is smaller than the target liquid level height of the evaporator, increasing the opening degree of the secondary throttle valve.

In the embodiment, the opening of the secondary throttle valve is controlled by the liquid level height of the evaporator and the target liquid level height of the evaporator, and when the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, the opening of the secondary throttle valve is reduced, so that the liquid level in the evaporator can be increased to the target liquid level of the evaporator; when the liquid level height of the evaporator is smaller than the target liquid level height of the evaporator, increasing the opening degree of the secondary throttling valve so that the liquid level in the evaporator can be reduced to the target liquid level of the evaporator; optionally, when the liquid level height of the evaporator is equal to the target liquid level height of the evaporator, the opening of the current secondary throttle valve is maintained unchanged.

It should be noted that the above solution of the preferred embodiment is only one specific implementation solution proposed in the present application, and other methods for controlling the opening degree of the two-stage throttle valve based on the liquid level height of the evaporator and the target liquid level height of the evaporator are all within the protection scope of the present application.

In order to accurately adjust the opening of the two-step throttle valve, in some embodiments, the controller is further configured to:

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttle valve is increased, the opening of the primary throttle valve is increased;

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttling valve is reduced, the opening of the primary throttling valve is reduced;

the negative deviation liquid level height is the difference between the economizer target liquid level height and a preset deviation height, and the positive deviation liquid level height is the sum of the economizer target liquid level height and the preset deviation height.

In this embodiment, when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and less than the positive deviation liquid level height, the liquid level height of the economizer is within a relatively moderate range, that is, the liquid level height of the economizer is within an allowable positive and negative deviation, at this time, the regulation trends of the primary throttle valve and the secondary throttle valve are kept consistent, the opening of the primary throttle valve is increased when the opening of the secondary throttle valve is increased, and the opening of the primary throttle valve is decreased when the opening of the secondary throttle valve is decreased, preferably, for reasonably controlling the primary throttle valve, the increase or decrease amplitude of the primary throttle valve is 50% of the increase or decrease amplitude of the secondary throttle valve. The negative deviation liquid level height is the difference between the economizer target liquid level height and a preset deviation height, the positive deviation liquid level height is the sum of the economizer target liquid level height and the preset deviation height, and the preset deviation height can be set according to actual conditions.

It should be noted that the above solution of the preferred embodiment is only one specific implementation solution proposed in the present application, and other methods for controlling the opening degree of the two-stage throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator are all within the protection scope of the present application.

In order to accurately adjust the opening of the two-step throttle valve, in some embodiments, the controller is further configured to:

when the liquid level height of the economizer is greater than or equal to a preset liquid level lower limit height and smaller than the negative deviation liquid level height, if the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, the opening degree of the primary throttling valve is kept;

and when the liquid level height of the economizer is greater than or equal to the preset liquid level lower limit height and smaller than the negative deviation liquid level height, if the liquid level height of the evaporator is less than or equal to the target liquid level height of the evaporator, increasing the opening degree of the primary throttle valve to a first preset opening degree.

In this embodiment, when the liquid level height of the economizer is greater than or equal to a preset liquid level lower limit height and less than the negative deviation liquid level height, it is indicated that the liquid level height of the economizer is relatively low but has not yet reached the preset lower limit, at this time, the liquid level height of the evaporator needs to be considered comprehensively, and when the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, the opening degree of the secondary throttle valve is reduced, the opening degree of the primary throttle valve is maintained, and the liquid level height of the economizer is gradually increased; the preset liquid level lower limit height can be set according to actual conditions, when the liquid level height of the evaporator is smaller than or equal to the target liquid level height of the evaporator, the opening degree of the secondary flow valve is kept unchanged or increased, at this time, the opening degree of the primary throttle valve needs to be increased to a first preset opening degree, and the first preset opening degree can be obtained through experiments.

It should be noted that the above solution of the preferred embodiment is only one specific implementation solution proposed in the present application, and other methods for controlling the opening degree of the two-stage throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator are all within the protection scope of the present application.

To accurately control the opening of the two-step throttle valve, in some embodiments, the controller is further configured to:

when the liquid level height of the economizer is greater than or equal to the positive deviation liquid level height and less than or equal to a preset liquid level upper limit height, if the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, reducing the opening degree of the primary throttle valve to a fourth preset opening degree;

and when the liquid level height of the economizer is greater than or equal to the positive deviation liquid level height and less than or equal to the preset liquid level upper limit height, if the liquid level height of the evaporator is less than or equal to the evaporator target liquid level height, the opening degree of the primary throttle valve is maintained.

In this embodiment, when the liquid level height of the economizer is greater than or equal to the positive deviation liquid level height and less than or equal to the preset liquid level upper limit height, it is described that the liquid level of the economizer is higher than the preset liquid level upper limit height, at this moment, the liquid level height of the evaporator needs to be considered comprehensively, when the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, the opening of the second-stage throttle valve is reduced, at this moment, in order to reduce the liquid level height of the economizer, the opening of the first-stage throttle valve should be reduced to a fourth preset opening, the preset liquid level upper limit height can be set according to actual conditions, and the fourth preset opening can be obtained through experiments. When the liquid level height of the evaporator is less than or equal to the target liquid level height of the evaporator, the opening degree of the secondary throttle valve is increased or unchanged, and the opening degree of the primary throttle valve is kept.

It should be noted that the above solution of the preferred embodiment is only one specific implementation solution proposed in the present application, and other methods for controlling the opening degree of the two-stage throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator are all within the protection scope of the present application.

To accurately control the opening of the two-step throttle valve, in some embodiments, the controller is further configured to:

when the liquid level height of the economizer is smaller than or equal to a preset liquid level lower limit height and the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, increasing the opening degree of the primary throttle valve to the first preset opening degree;

and when the liquid level height of the economizer is smaller than or equal to the preset liquid level lower limit height and the liquid level height of the evaporator is smaller than or equal to the target liquid level height of the evaporator, increasing the opening degree of the primary throttle valve to a second preset opening degree.

In this embodiment, when the liquid level height of the economizer is less than or equal to a preset liquid level lower limit height, the liquid level height of the economizer is lower, the liquid level height of the economizer needs to be increased while the liquid level height of the evaporator is referred to, when the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, the opening degree of the secondary throttle valve is reduced, and the liquid level height of the economizer is indirectly increased, but because the liquid level height of the economizer is not higher than the normal lower limit height, the opening degree of the primary throttle valve should be increased to the first preset opening degree; the preset lower limit height can be set according to actual conditions, when the liquid level height of the evaporator is less than or equal to the target liquid level height of the evaporator, the opening degree of the secondary throttle valve can be increased or kept unchanged, and in order to increase the liquid level height of the economizer, the opening degree of the primary throttle valve should be increased to a second preset opening degree. The second preset opening degree can be obtained through experiments, and preferably, in order to reasonably increase the liquid level height of the economizer, the second preset opening degree is 1.5 times of the first preset opening degree.

It should be noted that the above solution of the preferred embodiment is only one specific implementation solution proposed in the present application, and other methods for controlling the opening degree of the two-stage throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator are all within the protection scope of the present application.

To accurately control the opening of the two-step throttle valve, in some embodiments, the controller is further configured to:

when the liquid level height of the economizer is larger than the preset upper liquid level limit height and the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, reducing the opening degree of the primary throttle valve to a third preset opening degree;

and when the liquid level height of the economizer is larger than the preset upper liquid level limit height and the liquid level height of the evaporator is smaller than or equal to the target liquid level height of the evaporator, reducing the opening degree of the primary throttle valve to a fourth preset opening degree.

In this embodiment, when the liquid level height of the economizer is greater than the preset upper liquid level limit height, the liquid level height of the economizer is higher than this moment, the liquid level height of the economizer needs to be reduced while the liquid level height of the economizer is referred to, when the liquid level height of the evaporator is greater than the target liquid level height of the evaporator, the opening degree of the second-stage throttle valve is reduced, in order to accelerate the liquid level height reduction speed of the evaporator, the opening degree of the first-stage throttle valve should be reduced to a third preset opening degree, which can be obtained through experiments, when the liquid level height of the evaporator is less than or equal to the target liquid level height of the evaporator, the opening degree of the second-stage throttle valve should be increased or kept unchanged, and at this moment, the opening degree of the first-stage throttle valve should be reduced. Preferably, in order to reasonably adjust the descending speed of the liquid level height of the economizer, the third preset opening degree is 1.5 times of the fourth preset opening degree.

It should be noted that the above solution of the preferred embodiment is only one specific implementation solution proposed in the present application, and other methods for controlling the opening degree of the two-stage throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator are all within the protection scope of the present application.

The invention discloses a refrigeration system and a control method of a two-stage throttle valve, wherein the refrigeration system comprises a compressor and an economizer, wherein the economizer is used for separating gaseous refrigerant from liquid refrigerant; the primary throttle valve is arranged between the condenser and the economizer and used for throttling the refrigerant; the secondary throttle valve is arranged between the economizer and the evaporator and used for throttling the refrigerant; a controller configured to: acquiring the liquid level height of the economizer and the liquid level height of the evaporator; the opening degree of the first-stage throttling valve and the opening degree of the second-stage throttling valve are controlled based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator, so that the refrigerating system unit can run more stably and always runs under the optimal working condition, and the risks of air suction liquid entrainment and air supply liquid entrainment are effectively reduced.

In order to further illustrate the technical idea of the present invention, the present invention further provides a control method of a two-stage throttle valve, the method is applied to a refrigeration system comprising a compressor, an economizer, a one-stage throttle valve, a two-stage throttle valve and a controller, wherein the one-stage throttle valve is arranged between a condenser and the economizer, and the two-stage throttle valve is arranged between the economizer and an evaporator, as shown in fig. 2, the method comprises the following specific steps:

s201, acquiring the liquid level height of the economizer and the liquid level height of the evaporator.

In this step, the liquid level heights of the economizer and the evaporator are respectively obtained, and optionally, the liquid level heights of the economizer and the evaporator can be obtained by arranging liquid level meters in the economizer and the evaporator.

And S202, controlling the opening degrees of the primary throttle valve and the secondary throttle valve based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator.

In the step, after the liquid level heights of the economizer and the evaporator are obtained, the opening degrees of the primary throttle valve and the secondary throttle valve are controlled according to the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator, wherein the target liquid level height of the evaporator can be the liquid level height set by a user or can be automatically generated according to the running temperature of the refrigeration system adjusted by the user.

In order to accurately control the opening of the secondary throttling valve, in some embodiments, the opening of the primary throttling valve and the secondary throttling valve is controlled based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator, specifically:

when the liquid level height of the evaporator is larger than the target liquid level height of the evaporator, reducing the opening of the secondary throttle valve;

and when the liquid level height of the evaporator is smaller than the target liquid level height of the evaporator, increasing the opening degree of the secondary throttle valve.

Specifically, when the liquid level height of the evaporator is greater than the target evaporator liquid level height, the opening degree of the secondary throttling valve is reduced, so that the liquid level height of the evaporator is reduced to the target evaporator liquid level height, and when the liquid level height of the evaporator is less than the target evaporator liquid level height, the opening degree of the secondary throttling valve is increased, so that the liquid level height of the evaporator is increased to the target evaporator liquid level height. Optionally, when the liquid level height of the evaporator is equal to the target liquid level height of the evaporator, the opening degree of the two-stage throttle valve is maintained.

It should be noted that the above solution of the preferred embodiment is only one specific implementation solution proposed in the present application, and other methods for controlling the opening degree of the two-stage throttle valve based on the liquid level height of the evaporator and the target liquid level height of the evaporator are all within the protection scope of the present application.

In order to accurately control the opening of the two-stage throttling valve, in some embodiments, the opening of the first-stage throttling valve and the second-stage throttling valve is controlled based on the liquid level height of the economizer, the liquid level height of the evaporator and the target liquid level height of the evaporator, specifically:

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttle valve is increased, the opening of the primary throttle valve is increased;

when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and smaller than the positive deviation liquid level height, if the opening of the secondary throttling valve is reduced, the opening of the primary throttling valve is reduced;

the negative deviation liquid level height is the difference between the economizer target liquid level height and a preset deviation height, and the positive deviation liquid level height is the sum of the economizer target liquid level height and the preset deviation height.

Specifically, when the liquid level height of the economizer is greater than or equal to the negative deviation liquid level height and less than the positive deviation liquid level height, the liquid level height of the economizer is in a relatively moderate range, namely the liquid level height of the economizer is within an allowable positive and negative deviation, the regulation trends of the primary throttle valve and the secondary throttle valve are kept consistent, the opening of the primary throttle valve is increased when the opening of the secondary throttle valve is increased, and the opening of the primary throttle valve is decreased when the opening of the secondary throttle valve is decreased, preferably, the increase or decrease amplitude of the primary throttle valve is 50% of the increase or decrease amplitude of the secondary throttle valve. The negative deviation liquid level height is the difference between the economizer target liquid level height and a preset deviation height, the positive deviation liquid level height is the sum of the economizer target liquid level height and the preset deviation height, and the preset deviation height can be set according to actual conditions.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not necessarily depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.