Return steam dryness control system and control method of refrigerating system

Abstract

The invention relates to the technical field of refrigerating systems, and provides a return steam dryness control system and method for a refrigerating system, and the refrigerating system comprises a refrigerant liquid supply device which is used for providing refrigerant liquid; the control valve is arranged at the downstream of the refrigerant liquid supply device, and the control valve is used for controlling the flow of the refrigerant liquid; the evaporator is used for enabling the refrigerant liquid to absorb heat and be evaporated into refrigerant return steam, and the refrigerant return steam is gas or gas-liquid two-phase fluid; the return steam dryness measuring device is arranged at the downstream of the evaporator, and the return steam dryness measuring device is used for measuring the dryness of refrigerant return steam; and the return steam dryness measuring device is linked with the control valve. According to the return steam dryness control system and method of the refrigerating system, the return steam dryness is measured through the return steam dryness measuring device and fed back to the control valve, control over the return steam dryness of the refrigerating system is achieved, and while the refrigerating effect is guaranteed, the proper liquid supply amount is provided, and the energy consumption and the refrigerant charging amount are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration systems, and in particular to a refrigeration system return steam dryness control system and a control method. Background Art

[0002] The principle of the refrigeration system is mainly to utilize the phenomenon of heat absorption and heat release in the process of physical state change, and to realize the transfer of heat from low-temperature objects to high-temperature objects through the circulation of refrigerant, thereby achieving the purpose of refrigeration.

[0003] In the prior art, in order to ensure the refrigeration effect of the refrigeration system, an excessive amount of refrigerant liquid is usually provided, resulting in high energy consumption, a large amount of refrigerant filling, and serious waste of resources. Summary of the invention

[0004] The present invention provides a refrigeration system return steam dryness control system and a control method, which are used to solve the defect of excessive supply of refrigerant liquid in the prior art, realize quantitative supply of refrigerant liquid and reduce energy consumption.

[0005] The present invention provides a refrigeration system return steam dryness control system, comprising: a refrigerant liquid supply device, used for providing refrigerant liquid; A control valve, disposed downstream of the refrigerant liquid supply device, the control valve being used to control the flow rate of the refrigerant liquid; An evaporator, for the refrigerant liquid to absorb heat and evaporate into refrigerant vapor, wherein the refrigerant vapor is a gas or a gas-liquid two-phase fluid; A return steam dryness measuring device is arranged downstream of the evaporator, and is used to measure the dryness of the refrigerant return steam; and the return steam dryness measuring device is linked to the control valve.

[0006] According to a refrigeration system return vapor dryness control system provided by the present invention, the refrigerant liquid supply device and the control valve are connected via a first pipe; the control valve and the evaporator are connected via a second pipe; and the return vapor dryness measuring device is arranged on the outlet pipe of the evaporator.

[0007] According to a refrigeration system return steam dryness control system provided by the present invention, the outlet pipe of the evaporator includes a first straight pipe, a bent pipe and a second straight pipe connected in sequence, and the return steam dryness measuring device includes an impact type, and the return steam dryness measuring device is arranged at the bent pipe.

[0008] According to a refrigeration system return steam dryness control system provided by the present invention, the outlet pipe of the evaporator includes a first straight pipe, a bent pipe and a second straight pipe connected in sequence, and the return steam dryness measuring device includes a jacket type, and the return steam dryness measuring device is arranged at the second straight pipe.

[0009] According to a refrigeration system return vapor dryness control system provided by the present invention, an inner tube is provided inside the second straight tube, and the inner tube and the second straight tube are connected and supported by an insulator; and the refrigerant return vapor flows through the gap between the inner tube and the second straight tube.

[0010] The present invention also provides a method for controlling the dryness of return steam in a refrigeration system, comprising: The refrigerant liquid enters the evaporator and absorbs heat to evaporate, forming refrigerant return vapor; Determine the return steam dryness of refrigerant return steam; Based on the dryness feedback of the refrigerant return vapor, the flow rate of the refrigerant liquid is adjusted, thereby achieving dryness control of the refrigeration system.

[0011] According to the refrigeration system return steam quality control method provided by the present invention, the determination of the return steam quality of the refrigerant return steam comprises: Since the gas and liquid in the refrigerant return vapor have different impact strengths on the return vapor dryness measuring device; Based on the impact of refrigerant return steam on the return steam dryness measuring device, the return steam dryness measuring device outputs different capacitance values; The liquid content in the refrigerant return vapor is obtained based on the change in capacitance value, thereby determining the return vapor dryness of the refrigerant return vapor.

[0012] According to the refrigeration system return steam quality control method provided by the present invention, the determination of the return steam quality of the refrigerant return steam comprises: The pipeline where the refrigerant returns is a double-tube capacitor; When the refrigerant return vapor flows through the double-tube capacitor, the refrigerant return vapor with different fluid dryness outputs different capacitance values; The liquid content in the refrigerant return vapor is obtained based on different capacitance values, thereby determining the return vapor dryness of the refrigerant return vapor.

[0013] The refrigeration system return vapor dryness control system and control method provided by the present invention provide refrigerant liquid through a refrigerant liquid supply device, a control valve is arranged downstream of the refrigerant liquid supply device, the control valve controls the flow rate of the refrigerant liquid, the evaporator supplies the refrigerant liquid to absorb heat and evaporate into refrigerant return vapor, a return vapor dryness measuring device is arranged downstream of the evaporator, the return vapor dryness measuring device measures the dryness of the refrigerant return gas, and feeds back the return vapor dryness to the control valve to control the supply amount of the refrigerant liquid, thereby realizing the return vapor dryness control of the refrigeration system, providing an appropriate amount of liquid supply while ensuring the refrigeration effect, and reducing energy consumption and refrigerant filling amount. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 It is one of the schematic diagrams of the return steam dryness control system of the refrigeration system according to the embodiment of the present invention.

[0016] Figure 2 yes Figure 1 Schematic diagram of the installation location of the mid-return steam dryness measurement device.

[0017] Figure 3 This is the second schematic diagram of the refrigeration system return steam dryness control system according to an embodiment of the present invention.

[0018] Figure 4 yes Figure 3 One of the schematic diagrams of the installation location of the mid-return steam dryness measurement device.

[0019] Figure 5 yes Figure 3 Schematic diagram of the installation location of the mid-return steam dryness measurement device (part 2).

[0020] Reference numerals: 1. Refrigerant liquid supply device; 2. Control valve; 3. Evaporator; 4. Return steam dryness measuring device; 5. First pipeline; 6. Second pipeline; 7. Outlet pipeline; 71. First straight pipe; 72. Bend pipe; 73. Second straight pipe; 74. Inner pipe. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limitations on the embodiments of the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0023] Combine the following Figure 1-Figure 5 The present invention describes a refrigeration system return steam dryness control system.

[0024] like Figure 1 As shown, an embodiment of the present invention provides a refrigeration system return steam dryness control system, including a refrigerant liquid supply device 1, a control valve 2, an evaporator 3 and a return steam dryness measuring device 4.

[0025] Among them, the refrigerant liquid supply device 1 is used to provide refrigerant liquid; the refrigerant liquid is the basis of the refrigeration cycle, through which it absorbs heat and is converted into gas, thereby achieving a refrigeration effect. The control valve 2 is arranged downstream of the refrigerant liquid supply device 1, and the control valve 2 is used to control the flow rate of the refrigerant liquid. By accurately controlling the flow rate, the refrigeration effect and efficiency in the evaporator can be further adjusted. The evaporator 3 provides the refrigerant liquid with heat absorption and evaporation to become refrigerant return vapor, wherein the refrigerant return vapor is in the state of gas or gas-liquid two-phase fluid. The return vapor dryness measuring device 4 is arranged downstream of the evaporator 3, and the return vapor dryness measuring device 4 is used to measure the dryness of the refrigerant return vapor; dryness refers to the proportion of gas components in the refrigerant return vapor. The return vapor dryness measuring device 4 is linked with the control valve 2. According to the measured dryness result, the opening of the control valve 2 can be adjusted in real time, thereby adjusting the flow rate of the refrigerant liquid, and quantitative liquid supply can be achieved, while satisfying the refrigeration effect in the evaporator, ensuring low energy consumption.

[0026] It should be noted that the working process of the return steam dryness measuring device 4 and the control valve 2 is that the measured value electrical signal of the return steam dryness measuring device 4 is transmitted to the controller, and the controller outputs an electrical signal to the control valve 2 after signal conversion and calculation, and the control valve 2 performs the work of opening or closing or keeping unchanged, thereby realizing the linkage between the return steam dryness measuring device 4 and the control valve 2.

[0027] Among them, according to different needs and different types of refrigeration equipment, the specific structure of the evaporator 3 will also be different accordingly. Common evaporators include finned tube evaporators, spiral tube evaporators, plate evaporators, honeycomb jacket evaporators for biological products and wine fermentation tanks, channel jacket evaporators for biological products and wine fermentation tanks, etc. The specific structures of different types of evaporators can refer to the prior art and will not be repeated in the embodiments of the present invention. In addition, the specific type of evaporator can be selected according to actual needs, and no specific restrictions are made in the embodiments of the present invention.

[0028] like Figure 1 As shown, in a feasible embodiment of the present invention, the refrigerant liquid supply device 1 is connected to the control valve 2 through a first pipe 5, and the first pipe 5 is used to transport the refrigerant liquid from the refrigerant liquid supply device 1 to the control valve 2. The control valve 2 is connected to the evaporator 3 through a second pipe 6, and the second pipe 6 ensures that the refrigerant liquid can enter the evaporator 3 stably and controllably, so that the refrigerant liquid is in the evaporator 3; the return steam dryness measuring device 4 is arranged on the outlet pipe 7 of the evaporator 3, so that the return steam dryness measuring device 4 can accurately measure the dryness of the refrigerant return steam leaving the evaporator 3.

[0029] like Figure 2 As shown, in a feasible embodiment of the present invention, the outlet pipe of the evaporator 3 includes a first straight pipe 71, a curved pipe 72, and a second straight pipe 73 which are connected in sequence, and the return vapor dryness measuring device 4 includes an impact type, and the return vapor dryness measuring device 4 is arranged at the curved pipe 72. Since the gas and liquid in the refrigerant return vapor have different impact strengths with the return vapor dryness measuring device 4; based on the impact of the refrigerant return vapor on the return vapor dryness measuring device 4, the return vapor dryness measuring device 4 outputs different capacitance values; the liquid content in the refrigerant return vapor is obtained according to the change in capacitance value, thereby judging the return vapor dryness of the refrigerant return vapor. Generally speaking, the first straight pipe 71, the curved pipe 72, and the second straight pipe 73 are connected as one.

[0030] In a feasible embodiment of the present invention, the refrigerant is ammonia. Liquid ammonia has a high latent heat of evaporation and can absorb a large amount of heat during the evaporation process, thereby achieving an efficient refrigeration effect. When ammonia is used as a refrigerant, its emission and leakage problems can be controlled by appropriate safety measures and leak detection systems. In addition, compared with some halogenated hydrocarbon refrigerants, ammonia has a global warming potential (GWP) of 0 and has less impact on the environment.

[0031] In the above embodiments, when the return vapor dryness measuring device 4 adopts the impact type, the refrigerant liquid can also be other fluids with a large difference in gas phase density and liquid phase density in a saturated state. The gas and liquid in the refrigerant return vapor have different impact forces on the return vapor dryness measuring device 4, which will cause the capacitance value of the return vapor dryness measuring device 4 to change.

[0032] like Figure 3 As shown, in another feasible embodiment of the present invention, the outlet pipeline of the evaporator 3 includes a first straight pipe 71, a curved pipe 72, and a second straight pipe 73 connected in sequence, and the return steam dryness measuring device 4 includes a jacket type, and the return steam dryness measuring device 4 is arranged at the second straight pipe 73; it not only ensures the smooth flow of the refrigerant return steam in the pipeline, but also facilitates the installation of monitoring equipment at a suitable position. Among them, the fluid dryness of the refrigerant return steam affects the capacitance value of the return steam dryness measuring device; based on the change of the capacitance value, the liquid content in the refrigerant return steam is obtained, thereby judging the return steam dryness of the refrigerant return steam.

[0033] It should be noted that the return steam dryness measuring device can measure capacitance. Since the gas-liquid content ratio in the refrigerant return steam is different, the capacitance of the return steam dryness measuring device is also different. By measuring the capacitance, the gas-liquid two-phase ratio, that is, the dryness, can be obtained.

[0034] In a feasible embodiment of the present invention, the refrigerant is carbon dioxide. In this embodiment, liquid carbon dioxide is transported to the refrigerant liquid supply device 1 as a refrigerant liquid, and enters the control valve 2 through the first pipeline. After the flow rate is adjusted by the control valve 2, the liquid carbon dioxide enters the evaporator 3 for evaporation and heat absorption. The return steam dryness measuring device 4 arranged on the outlet pipe 7 of the evaporator 3 can accurately measure the dryness of the refrigerant return steam, and adjust the opening of the control valve 2 in real time according to the measurement result, so as to ensure the stable operation of the refrigeration system and the efficient refrigeration effect.

[0035] like Figure 4 and Figure 5 As shown, in a feasible embodiment of the present invention, an inner tube 74 is sleeved inside the second straight tube 73, and the inner tube 74 and the second straight tube 73 are connected and supported by an insulator (not shown in the figure); the refrigerant return vapor flows through the gap between the inner tube 74 and the second straight tube 73. The presence of the insulator causes the second straight tube 73 and the inner tube 74 to form a capacitor. The gas-liquid content ratio of the gas-liquid two-phase flow between the two tubes is different, and the capacitance between the two tubes is also different. By measuring the capacitance, the gas-liquid two-phase ratio, that is, the dryness, can be obtained.

[0036] It should be noted that both the second straight tube 73 and the inner tube 74 need to be conductors to form a capacitor.

[0037] Therefore, in the refrigeration system return vapor dryness control system provided by the embodiment of the first aspect of the present invention, the refrigerant liquid enters the evaporator 3 after passing through the control valve 2, absorbs heat and evaporates into refrigerant return vapor in the evaporator 3. The refrigerant return vapor is usually a gas or a gas-liquid two-phase fluid. The refrigerant return vapor is measured for its dryness by the return vapor dryness measuring device 4, and the dryness is fed back to the control valve 2. The control valve 2 controls the liquid supply amount of the refrigerant liquid supply device to realize the dryness control of the refrigeration system. While ensuring the normal operation of the refrigeration system, it can provide an appropriate amount of refrigerant liquid and reduce energy consumption.

[0038] Another aspect of the present invention is to provide a method for controlling the dryness of return steam in a refrigeration system, comprising: S1, the refrigerant liquid enters the evaporator 3 to absorb heat and evaporate, forming refrigerant return vapor.

[0039] In step S1, the refrigerant liquid is sent to the evaporator 3. The evaporator 3 is a key component in the refrigeration system. Its main function is to absorb external heat and evaporate the refrigerant liquid into refrigerant return vapor. In this process, all or part of the refrigerant liquid is transformed from liquid to gas, while absorbing a large amount of heat to provide cooling capacity for the refrigeration system.

[0040] S2. Determine the return steam dryness of the refrigerant return steam.

[0041] Step S2 is to measure the return vapor dryness of the refrigerant return vapor. The return vapor dryness is an important parameter to measure the proportion of liquid and gas in the refrigerant return vapor, and has an important impact on the performance of the refrigeration system. By measuring the return vapor dryness, the evaporation of the refrigerant in the evaporator and the operating status of the refrigeration system can be understood.

[0042] In actual operation, a variety of methods can be used to measure the dryness of refrigerant return vapor, such as pressure drop method, circuit method, weighing method, specific gravity method, etc.

[0043] S3. Based on the dryness feedback of the refrigerant return vapor, the flow rate of the refrigerant liquid is adjusted to achieve dryness control of the refrigeration system.

[0044] Step S3 is to adjust the flow rate of the refrigerant liquid based on the dryness feedback of the refrigerant return vapor. By accurately controlling the flow rate of the refrigerant liquid, the refrigerant return vapor dryness can be effectively adjusted. When the return vapor dryness is too low, it means that the refrigerant liquid is not completely evaporated in the evaporator. At this time, the flow rate of the refrigerant liquid should be appropriately reduced to reduce the amount of refrigerant liquid entering the evaporator so that more refrigerant liquid can be fully evaporated. On the contrary, when the return vapor dryness is too high, it means that the refrigerant liquid evaporates too quickly in the evaporator. At this time, the flow rate of the refrigerant liquid should be appropriately increased to increase the amount of refrigerant liquid entering the evaporator to ensure that the refrigerant can fully evaporate and absorb enough heat.

[0045] In a feasible embodiment of the present invention, in step S2, it includes: S211. Since the gas and liquid in the refrigerant return vapor have different impact forces on the return vapor dryness measuring device 4, the gas part has a relatively small impact on the measuring device due to its lighter weight and higher fluidity, while the liquid part has a relatively large impact on the measuring device due to its larger weight and lower fluidity.

[0046] S212. Based on the difference in impact of the refrigerant return vapor on the return vapor dryness measuring device 4, the return vapor dryness measuring device 4 outputs different capacitance values.

[0047] In the above steps, based on the impact difference of the refrigerant return vapor on the return vapor dryness measuring device 4, the capacitance sensor designed inside the device can sense the change of this impact force and convert it into a corresponding capacitance value output. When the liquid content in the refrigerant return vapor increases, the impact force on the measuring device increases, causing the capacitance value to change accordingly; conversely, when the liquid content decreases, the capacitance value will also increase accordingly.

[0048] S13. The liquid content in the refrigerant return vapor is obtained according to the change in the capacitance value, thereby determining the return vapor dryness of the refrigerant return vapor.

[0049] The return vapor dryness measuring device 4 is internally or externally equipped with a microprocessor or a similar data processing unit, which can receive and process the capacitance value output by the capacitance sensor. Through a preset algorithm or model, the data processing unit can accurately calculate the liquid content in the refrigerant return vapor according to the change of the capacitance value, thereby further determining the return vapor dryness of the refrigerant return vapor.

[0050] In another feasible embodiment of the present invention, in step S2, it includes: S221. Set the refrigerant return steam pipeline as a double-tube capacitor.

[0051] In step S221, the dual-tube capacitor structure is usually composed of two parallel metal tubes, with an insulating medium filled between them, forming a capacitive sensor.

[0052] S222. When the refrigerant return vapor flows through the double-tube capacitor, the refrigerant return vapor with different fluid dryness outputs different capacitance values.

[0053] In step S222, when the refrigerant vapor returns through the double-tube capacitor, due to the different dryness of the gas and liquid in the refrigerant vapor return, their effects on the capacitance sensor will also be different. Specifically, due to the difference in their physical properties (such as dielectric constant, density, etc.), the gas and liquid in the refrigerant vapor return will cause the capacitance value of the capacitance sensor to change. This change is directly related to the liquid content (i.e., dryness) in the refrigerant vapor return. Therefore, by measuring the change in capacitance value, the dryness information of the refrigerant vapor return can be indirectly obtained.

[0054] S223. The liquid content in the refrigerant return vapor is calculated based on different capacitance values, thereby determining the return vapor dryness of the refrigerant return vapor.

[0055] In step S223, a preset algorithm or model may be used to calculate the liquid content in the refrigerant return vapor.

[0056] Therefore, the return vapor dryness control method of the refrigeration system provided by the present invention realizes the return vapor dryness control of the refrigeration system by monitoring the return vapor dryness and controlling the supply amount of the refrigerant liquid based on the return vapor dryness, thereby reducing energy consumption and refrigerant filling amount while ensuring the refrigeration effect.

[0057] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0058] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "mode", "specific mode", or "some modes" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or mode are included in at least one embodiment or mode of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or mode. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or modes in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or modes described in this specification and the features of the different embodiments or modes, without contradiction.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A refrigeration system return steam dryness control system, characterized in that: include: A refrigerant liquid supply device (1), used for providing refrigerant liquid; A control valve (2) is arranged downstream of the refrigerant liquid supply device (1), and the control valve (2) is used to control the flow rate of the refrigerant liquid; An evaporator (3) for the refrigerant liquid to absorb heat and evaporate into refrigerant return vapor, wherein the refrigerant return vapor is a gas or a gas-liquid two-phase fluid; A return steam dryness measuring device (4) is arranged downstream of the evaporator (3), and the return steam dryness measuring device (4) is used to measure the dryness of the refrigerant return steam; and the return steam dryness measuring device (4) is linked to the control valve (2).

2. The refrigeration system return steam dryness control system according to claim 1, characterized in that: The refrigerant liquid supply device (1) is connected to the control valve (2) via a first pipe (5); the control valve (2) is connected to the evaporator (3) via a second pipe (6); and the return steam dryness measuring device (4) is arranged on an outlet pipe (7) of the evaporator (3).

3. The refrigeration system return steam dryness control system according to claim 2, characterized in that: The outlet pipe (7) of the evaporator (3) comprises a first straight pipe (71), a curved pipe (72) and a second straight pipe (73) which are connected in sequence, and the return steam dryness measuring device (4) comprises an impact type, and the return steam dryness measuring device (4) is arranged at the curved pipe (72).

4. The refrigeration system return steam dryness control system according to claim 2, characterized in that: The outlet pipe of the evaporator (3) comprises a first straight pipe (71), a curved pipe (72) and a second straight pipe (73) which are connected in sequence, and the return steam dryness measuring device (4) comprises a jacket type, and the return steam dryness measuring device (4) is arranged at the second straight pipe (73).

5. The refrigeration system return steam dryness control system according to claim 4, characterized in that: An inner tube (74) is sleeved inside the second straight tube (73); the inner tube (74) and the second straight tube (73) are connected and supported by an insulator; and the refrigerant return vapor flows through a gap between the inner tube (74) and the second straight tube (73).

6. A method for controlling the dryness of return steam in a refrigeration system, characterized in that: include: The refrigerant liquid enters the evaporator (3) and absorbs heat to evaporate, forming refrigerant return vapor; Determine the return steam dryness of refrigerant return steam; Based on the dryness feedback of the refrigerant return vapor, the flow rate of the refrigerant liquid is adjusted, thereby achieving dryness control of the refrigeration system.

7. The method for controlling the return steam dryness of a refrigeration system according to claim 6, characterized in that: Determining the return steam dryness of the refrigerant return steam comprises: Since the gas and liquid in the refrigerant return vapor have different impact strengths on the return vapor dryness measuring device (4); Based on the impact of refrigerant return steam on the return steam dryness measuring device (4), the return steam dryness measuring device (4) outputs different capacitance values; The liquid content in the refrigerant return vapor is obtained based on the change in capacitance value, thereby determining the return vapor dryness of the refrigerant return vapor.

8. The method for controlling the return steam dryness of a refrigeration system according to claim 6, characterized in that: Determining the return steam dryness of the refrigerant return steam comprises: The pipeline where the refrigerant returns is a double-tube capacitor; When the refrigerant return vapor flows through the double-tube capacitor, the refrigerant return vapor with different fluid dryness outputs different capacitance values; The liquid content in the refrigerant return vapor is obtained based on different capacitance values, thereby determining the return vapor dryness of the refrigerant return vapor.

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