Capacitive liquid level control device

Abstract

The utility model relates to the technical field of liquid level control devices, and discloses a capacitance type liquid level control device which comprises a compressor, a condenser, a throttling liquid supply electric control assembly and an evaporator which are sequentially connected through pipelines, the other end of the evaporator is connected with the compressor through a pipeline, and a liquid level bypass pipe is arranged on one side of the evaporator. According to the non-contact type capacitance liquid level switch, when the non-contact type capacitance liquid level switch is used, due to the fact that the sensor is arranged externally and does not make direct contact with refrigerants, the liquid level can be adjusted or the sensor can be replaced under the condition that a refrigerating system is not affected, cost is low, and limitation is low; in order to solve the problem that the liquid level is sensed mistakenly due to the existence of bubbles generated in the refrigerant evaporation process, the device detects the liquid level by measuring the change of the capacitance value, the influence of the bubbles is avoided, and the detection precision is high.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid level control devices, in particular to a capacitive liquid level control device. Background Art

[0002] Due to the advantages of high efficiency, energy saving and less refrigerant charge, the falling film type chiller (heat pump) unit has become the market mainstream. Among them, the liquid level control device of the unit is a key technology, and the existing control methods are as follows:

[0003] 1. Electronic expansion valve - liquid level sensor throttling control method: The electronic expansion valve and the liquid level sensor form a closed-loop control system to automatically control the liquid level height in the evaporator.

[0004] 2. Electronic expansion valve superheat control method: The electronic expansion valve automatically adjusts the opening according to the suction superheat to achieve the purpose of automatic control of the refrigeration system.

[0005] 3. Orifice throttling control method: The refrigerant throttles through the orifice, and uses the self-adjusting characteristics of the orifice and the combination of multiple orifices to achieve the purpose of throttling control.

[0006] However, when the existing control methods are used, they have the following disadvantages:

[0007] 1. Problems of the electronic expansion valve - liquid level sensor throttling control method: The electronic expansion valve and the supporting liquid level sensor are relatively expensive, which is not conducive to cost reduction.

[0008] 2. Disadvantages of the electronic expansion valve superheat control method: The addition of the superheat pipe group increases the cost of the heat exchanger, resulting in a higher manufacturing cost, and there is also energy loss caused by suction superheat.

[0009] 3. Disadvantages of the orifice throttling control method: The cost is the lowest, but when the actual working conditions of the unit change greatly, the orifice cannot automatically match the change of the working conditions, and it is greatly limited in practical applications.

[0010] 4. For the "ultrasonic liquid level control device" described in Patent No. 202320590421.9, due to the existence of bubbles generated during the refrigerant evaporation process, there may be a problem of mis-sensing the liquid level, which affects the reliability of ultrasonic liquid level sensing. Content of the Utility Model

[0011] The purpose of the utility model is to solve the problems existing in the prior art, and a capacitive liquid level control device is proposed.

[0012] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0013] Capacitive liquid level control device, including a compressor, a condenser, a throttling liquid supply electronic control component and an evaporator connected in sequence through pipelines, and the other end of the evaporator is connected to the compressor through a pipeline. A liquid level bypass pipe is arranged on one side of the evaporator, and two non-contact capacitive liquid level switches are arranged on the outer side of the liquid level bypass pipe, and one of the non-contact capacitive liquid level switches is located above the other non-contact capacitive liquid level switch.

[0014] Preferably, the throttling liquid supply electronic control component includes a main orifice plate, a solenoid valve and an auxiliary orifice plate. Both ends of the main orifice plate are respectively connected to the condenser and the evaporator through pipelines. The solenoid valve and the auxiliary orifice plate are connected through a pipeline, and the other ends of the solenoid valve and the auxiliary orifice plate are respectively connected to the pipelines on both sides of the main orifice plate through pipelines.

[0015] Preferably, the liquid level bypass pipe includes a vertical pipe and two horizontal pipes. Both ends of the vertical pipe are communicated with the inner cavity of the evaporator through the corresponding horizontal pipes, and the two non-contact capacitive liquid level switches are located on the outer side of the vertical pipe.

[0016] Preferably, the non-contact capacitive liquid level switch is electrically connected to the solenoid valve.

[0017] Preferably, a plurality of auxiliary orifice plates are provided, and several auxiliary orifice plates are arranged in parallel.

[0018] Preferably, the evaporator is a falling film evaporator.

[0019] Compared with the prior art, the beneficial effects of the present utility model are:

[0020] In the present utility model, by adopting a non-contact capacitive liquid level switch, during use, on the one hand, since the sensor is externally placed and does not directly contact the refrigerant, the liquid level can be adjusted or the sensor can be replaced without affecting the refrigeration system, with low cost and few limitations. On the other hand, compared with the prior art where ultrasonic sensing is used to sense the liquid level, there may be a problem of false liquid level sensing due to the presence of bubbles generated during the evaporation process of the refrigerant. This device detects the liquid level by measuring the change in capacitance value and will not be affected by bubbles, with high detection accuracy. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the capacitive liquid level control device proposed by the present utility model.

[0022] In the figure: 1. Compressor; 2. Condenser; 3. Evaporator; 4. Non-contact capacitive liquid level switch; 5. Main orifice plate; 6. Liquid level bypass pipe; 7. Solenoid valve; 8. Auxiliary orifice plate; 9. Vertical pipe; 10. Horizontal pipe. Detailed Embodiment

[0023] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments.

[0024] Referring to Figure 1 , a capacitive liquid level control device includes a compressor 1, a condenser 2, a throttling liquid supply electronic control component, and an evaporator 3 connected in sequence through pipelines. The evaporator 3 is a falling film evaporator or a flooded evaporator, and the other end of the evaporator 3 is connected to the compressor 1 through a pipeline. A liquid level bypass pipe 6 is provided on one side of the evaporator 3, and two non-contact capacitive liquid level switches 4 are provided outside the liquid level bypass pipe 6, and one of the non-contact capacitive liquid level switches 4 is located above the other non-contact capacitive liquid level switch 4.

[0025] When this device is in use: The high-temperature and high-pressure gas discharged by the compressor 1 is cooled to a normal-temperature and high-pressure liquid through the condenser 2. The normal-temperature and high-pressure liquid flows through the main orifice plate 5 and the auxiliary orifice plate 8 for throttling through the corresponding pipelines (the throttling of the auxiliary orifice plate 8 is controlled by the solenoid valve 7). After throttling, the pressure decreases and it becomes a normal-temperature and low-pressure liquid. The low-pressure liquid enters the evaporator 3 to evaporate into a low-temperature and low-pressure gas and returns to the compressor 1 to complete a working cycle. Among them, a small amount of refrigerant and refrigerant oil that are not completely evaporated are at the bottom of the cylinder body and maintain a certain liquid level height;

[0026] When the unit is operating, the refrigerant enters the evaporator 3 through the pipeline and the main orifice plate 5. If the load of the unit increases, the evaporation amount of the refrigerant also increases correspondingly, and the liquid level of the evaporator 3 drops accordingly. The liquid level in the liquid level bypass pipe 6 drops synchronously. When the liquid level is lower than the position of the lowest non-contact capacitive liquid level switch 4, the solenoid valve 7 is energized and opened. The refrigerant liquid flows through the auxiliary orifice plate 8 through the bypass pipeline, and the main orifice plate 5 and the auxiliary orifice plate 8 supply liquid at the same time, and the mass flow rate of the refrigerant increases; when the load of the unit decreases, the liquid level rises. When it rises to the liquid level corresponding to the non-contact capacitive liquid level switch 4 at the higher position, the solenoid valve 7 is de-energized and closed, and the passage of the auxiliary orifice plate 8 is closed. The refrigerant can only flow to the evaporator through the main orifice plate 5. At this time, the mass flow rate of the refrigerant decreases. By adopting the non-contact capacitive liquid level switch 4 in this device, on the one hand, because the sensor is externally placed and does not directly contact the refrigerant, the liquid level can be adjusted or the sensor can be replaced without affecting the refrigeration system, with low cost and few restrictions. On the other hand, compared with the prior art where ultrasonic sensing is used to sense the liquid level, there may be a problem of false liquid level sensing due to the presence of bubbles generated during the evaporation process of the refrigerant. This device detects the liquid level by measuring the change in capacitance value and will not be affected by bubbles, with high detection accuracy.

[0027] In this embodiment, the throttling liquid supply electronic control assembly includes a main orifice plate 5, a solenoid valve 7, and an auxiliary orifice plate 8. Both ends of the main orifice plate 5 are respectively connected to the condenser 2 and the evaporator 3 through pipelines. The solenoid valve 7 and the auxiliary orifice plate 8 are connected through a pipeline. The other ends of the solenoid valve 7 and the auxiliary orifice plate 8 are respectively connected to the pipelines on both sides of the main orifice plate 5 through pipelines. The high-temperature and high-pressure gas discharged by the compressor 1 is cooled to normal-temperature and high-pressure liquid through the condenser 2. The normal-temperature and high-pressure liquid passes through the pipeline, flows through the main orifice plate 5 and the auxiliary orifice plate 8 for throttling (the throttling of the auxiliary orifice plate 8 is controlled by the solenoid valve 7, and whether to use it can be selected). After throttling, the pressure decreases and becomes normal-temperature and low-pressure liquid.

[0028] In this embodiment, the liquid level bypass pipe 6 includes a vertical pipe 9 and two horizontal pipes 10. Both ends of the vertical pipe 9 are communicated with the inner cavity of the evaporator 3 through the corresponding horizontal pipes 10, so that the liquid level in the evaporator 3 is flush with the liquid level in the vertical pipe 9. The two non-contact capacitive liquid level switches 4 are located outside the vertical pipe 9. The non-contact capacitive liquid level switch 4 is electrically connected to the solenoid valve 7. When the liquid level height in the evaporator 33 is higher than the upper non-contact capacitive liquid level switch 4 or lower than the lower non-contact capacitive liquid level switch 4, (in the non-contact capacitive sensor, the electrode does not directly contact the medium, but measures through an insulating layer (i.e., the vertical pipe 9). The dielectric constants of liquids and gases (including air and bubbles) usually have significant differences. When the liquid approaches the electrode of the non-contact capacitive sensor, the change in the dielectric constant will cause a measurable capacitance change, thereby detecting the liquid level. Even if there are bubbles, due to the dielectric constant difference between the liquid and the bubbles, the sensor can still distinguish the liquid and the bubbles and accurately measure the actual height of the liquid), the sensor cooperates with the control processor in the prior art to realize the opening and closing of the solenoid valve 7, thereby meeting the requirement of automatic adjustment of the unit load. And this device can control the liquid level height in the evaporator 3 within a preset reasonable range, meeting the requirement of automatic adjustment of the unit load. Moreover, the structure is simple, easy to manufacture, convenient to repair, and the overall manufacturing cost is low, solving the problems of high cost or low reliability existing in various liquid level control methods in the prior art.

[0029] In this embodiment, a plurality of auxiliary orifice plates 8 are provided, and several auxiliary orifice plates 8 are arranged in parallel. Using a plurality of auxiliary orifice plates 8 makes the liquid level adjustment smoother.

[0030] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A capacitive liquid level control device, comprising a compressor, a condenser, a throttling liquid supply electric control component and an evaporator which are sequentially connected through pipelines, and the other end of the evaporator is connected to the compressor through a pipeline, and is characterized in that: One side of the evaporator is provided with a liquid level bypass pipe, and two non-contact capacitive liquid level switches are arranged on the outer side of the liquid level bypass pipe, and one of the non-contact capacitive liquid level switches is located above the other non-contact capacitive liquid level switch.

2. The capacitive liquid level control device according to claim 1, characterized in that: The throttling liquid supply electronic control assembly includes a main orifice plate, a solenoid valve and an auxiliary orifice plate. Both ends of the main orifice plate are respectively connected with the condenser and the evaporator through pipelines. The solenoid valve and the auxiliary orifice plate are connected through a pipeline, and the other ends of the solenoid valve and the auxiliary orifice plate are respectively connected with the pipelines on both sides of the main orifice plate through pipelines.

3. The capacitive liquid level control device according to claim 2, characterized in that: The liquid level bypass pipe includes a vertical pipe and two horizontal pipes. Both ends of the vertical pipe are communicated with the inner cavity of the evaporator through the corresponding horizontal pipes, and the two non-contact capacitive liquid level switches are located on the outer side of the vertical pipe.

4. The capacitive liquid level control device according to claim 3, characterized in that: The non-contact capacitive liquid level switch is electrically connected with the solenoid valve.

5. The capacitive liquid level control device according to claim 3, characterized in that: A plurality of auxiliary orifice plates are provided, and several auxiliary orifice plates are arranged in parallel.

6. The capacitive liquid level control device according to claim 1, characterized in that: The evaporator is a falling film evaporator or a flooded evaporator.

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