Flash tank pressure control system of air conditioner

Abstract

The utility model discloses a flash tank pressure control system of an air conditioner. The flash tank pressure control system comprises a first-stage throttling device and a second-stage throttling device, the first-stage throttling device comprises a first throttling pipe, a differential pressure valve, a second throttling pipe and a capillary tube, one end of the first throttling pipe is communicated with one end of the second throttling pipe through the differential pressure valve, the other end of the first throttling pipe is communicated with the other end of the second throttling pipe through the capillary tube, and the first throttling pipe and the second throttling pipe are each provided with an outlet; the secondary throttling device comprises a first electronic expansion valve; the first electronic expansion valve is mounted at one port of the flash tank; and the other port of the flash tank is communicated with the first throttle pipe. By means of the arrangement, the capacity and energy efficiency of the air conditioner are effectively improved, and system oil return can be guaranteed when the differential pressure valve is small in opening degree.

Description

Technical Field

[0001] The utility model relates to the field of air-conditioning heat pumps, in particular to a flash tank pressure control system of an air conditioner. Background Art

[0002] The current heat pump flash tank system is in the initial development stage. The primary and secondary throttling of the unit are generally carried out in the form of dual electronic expansion valves or capillary tubes with electronic expansion valves.

[0003] The prior art with publication number CN216203957U discloses an air conditioning system, including a compressor, a condenser, a throttling device and an evaporator, the evaporator including a vertical gas collecting pipe, the top of the vertical gas collecting pipe is connected to the suction port of the compressor through the suction pipe, the bottom of the vertical gas collecting pipe is provided with a liquid return pipe, the other end of the liquid return pipe is connected to the suction pipe, and a pressure differential valve is provided on the liquid return pipe, and the pressure differential valve opens the liquid return pipe when the pressure difference between the vertical gas collecting pipe and the suction pipe reaches a preset value. When the pressure at the inlet of the liquid return pipe is greater than the pressure difference △P≥m at the outlet of the capillary section, the pressure differential valve opens (m is the pressure differential value for starting the pressure differential valve, which is selected and adopted according to design requirements), otherwise the pressure differential valve closes.

[0004] The existing technology mainly has the following problems:

[0005] 1) For the system cycle, when the pressure difference before and after the differential pressure valve is small, a larger opening is required. However, the simple differential pressure valve has a smaller valve opening, resulting in a small mass flow rate and poor unit energy efficiency. 2) A larger differential pressure valve is required to match the heat pump system. 3) When the differential pressure valve opening is too small, the unit oil return problem will be more obvious. Sometimes the oil cannot be brought over, which will cause the compressor to burn. Utility Model Content

[0006] In order to solve the problem of poor energy efficiency of units in the prior art, the purpose of the utility model is to provide an air conditioner and its flash tank pressure control system, which can ensure a certain fixed flow and provide a certain refrigerant flow when the pressure difference is small, thereby improving the energy efficiency of the air conditioning capacity.

[0007] In order to achieve the above-mentioned purpose, the utility model adopts the following technical scheme: a flash tank pressure control system, including a primary throttling device and a secondary throttling device; the primary throttling device includes a first throttling tube, a pressure differential valve, a second throttling tube and a capillary tube, one end of the first throttling tube and one end of the second throttling tube are connected through the pressure differential valve, the other end of the first throttling tube and the other end of the second throttling tube are connected through the capillary tube, and the first throttling tube and the second throttling tube are both provided with outlets; the secondary throttling device includes a first electronic expansion valve; the first electronic expansion valve is installed at a port of the flash tank; the other port of the flash tank is connected to the first throttling tube.

[0008] Preferably, the flash tank is connected to the enthalpy replenishing port of the compressor via an enthalpy injection pipe.

[0009] Preferably, a second electronic expansion valve is installed on the enthalpy spray tube.

[0010] Preferably, the outlet of the compressor is connected to the D port of the four-way valve, the E port of the four-way valve is connected to a port of the first heat exchanger, the S port of the four-way valve is connected to the inlet of the compressor, the C port of the four-way valve is connected to a port of the second heat exchanger, the other port of the first heat exchanger is connected to the flash tank through the first electronic expansion valve, and the other port of the second heat exchanger is connected to the second throttling tube.

[0011] Preferably, the first heat exchanger is equipped with an axial flow fan.

[0012] Preferably, the second heat exchanger is a water-side heat exchanger.

[0013] Preferably, a gas-liquid separator is installed on the pipeline between the S port of the four-way valve and the inlet of the compressor.

[0014] An air conditioner comprises the above-mentioned flash tank pressure control system.

[0015] The beneficial effects of the technical solution of the utility model are as follows: the first-stage throttling device is used in the form of a pressure differential valve and a capillary throttling, the capillary ensures a fixed flow rate, and the pressure differential valve is adjusted according to the pressure difference before and after the first-stage throttling device; under small pressure ratio conditions, the refrigerant flow rate passing through the pressure differential valve is smaller, and under large pressure ratio conditions, the refrigerant flow rate passing through the pressure differential valve is larger; in this way, sufficient intermediate pressure is ensured to achieve smooth air replenishment, which not only ensures stable operation of the unit, but also increases the stability of the system and reduces the probability of sudden changes and inability to adjust the unit.

[0016] In the above scheme, a capillary tube and a pressure differential valve are connected in parallel. Because there are two circulation paths, such a large pressure differential valve is not needed. A smaller pressure differential valve can be selected, which may be a better match for large heat pump systems. One side of the capillary tube is fixedly circulated. When the pressure difference before and after the pressure differential valve is small, the pressure differential valve can also supplement a certain amount of refrigerant circulation, thereby effectively improving the energy efficiency of the air conditioner and ensuring the oil return of the system when the pressure differential valve is opened at a small degree. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the schematic diagram of the flash tank pressure control system.

[0018] Figure numerals: 1. compressor; 2. four-way valve; 3. first heat exchanger; 4. first electronic expansion valve; 5. flash tank; 6. gas-liquid separator; 7. second electronic expansion valve; 8. second heat exchanger; 9. primary throttling device; 91. first throttling tube; 92. differential pressure valve; 93. second throttling tube; 94. capillary tube; 10. axial flow fan. DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0020] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0021] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "plurality" means two or more, unless otherwise clearly defined.

[0022] In the present invention, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like 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 it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature. Example

[0024] like Figure 1 A flash tank pressure control system is shown, comprising a primary throttling device 9 and a secondary throttling device; the primary throttling device 9 comprises a differential pressure valve 92, a capillary tube 94, a first throttling tube 91 and a second throttling tube 93, one end of the first throttling tube 91 and one end of the second throttling tube 93 are connected through the differential pressure valve 92, the other end of the first throttling tube 91 and the other end of the second throttling tube 93 are connected through the capillary tube 94, and the first throttling tube 91 and the second throttling tube 93 are both provided with outlets; the secondary throttling device comprises a first electronic expansion valve 4; the first electronic expansion valve 4 is installed at one port of the flash tank 5; the other port of the flash tank 5 is connected to the first throttling tube 91.

[0025] In this way, the primary throttling device 9 is used in a throttling manner using a differential pressure valve 92 and a capillary tube 94. The capillary tube 94 ensures a fixed flow rate, and the differential pressure valve 92 is adjusted according to the pressure difference before and after the primary throttling device 9. Under low pressure ratio conditions, the refrigerant flow through the differential pressure valve 92 is smaller, and under high pressure ratio conditions, the refrigerant flow through the differential pressure valve 92 is larger. Enough intermediate pressure is ensured for air replenishment to ensure stable operation of the unit.

[0026] In this embodiment, further, the flash tank 5 is connected to the enthalpy replenishing port of the compressor 1 through the enthalpy spraying pipe; the second electronic expansion valve 7 is installed on the enthalpy spraying pipe. With such a configuration, both the throttling positions and the enthalpy spraying realize the gradual flow adjustment, avoiding the sudden change of flow caused by the direct switch of the unit solenoid valve, or the flow cannot be adjusted when the capillary tube 94 is used; improving the stability of the system, avoiding the sudden change of the unit state, and realizing direct control of the amount of enthalpy spraying and the flow entering the evaporator; adapting to the control hardware of the existing economizer system of most manufacturers, reducing the demand for hardware development.

[0027] In this embodiment, the outlet of the compressor 1 is connected to the D port of the four-way valve 2, the E port of the four-way valve 2 is connected to a port of the first heat exchanger 3, the S port of the four-way valve 2 is connected to the inlet of the compressor 1, the C port of the four-way valve 2 is connected to a port of the second heat exchanger 8, the other port of the first heat exchanger 3 is connected to the flash tank 5 through the first electronic expansion valve 4, and the other port of the second heat exchanger 8 is connected to the second throttling tube 93. Further, the first heat exchanger 3 is equipped with an axial flow fan 10; the second heat exchanger 8 is a water-side heat exchanger. Further, a gas-liquid separator 6 is installed on the pipeline between the S port of the four-way valve 2 and the inlet of the compressor 1.

[0028] An air conditioner comprises the above-mentioned flash tank pressure control system.

[0029] The air conditioner uses the above flash tank pressure control system to adjust the pressure of the flash tank 5 in the following manner:

[0030] The control method of the primary throttling device 9 is as follows: the capillary tube 94 ensures a fixed flow rate, and the differential pressure valve 92 is adjusted according to the pressure difference before and after the primary throttling device 9. Specifically, under the condition of small pressure ratio, the refrigerant flow rate passing through the differential pressure valve 92 is smaller, and under the condition of large pressure ratio, the refrigerant flow rate passing through the differential pressure valve 92 is larger; it is ensured that there is sufficient intermediate pressure for air replenishment to ensure stable operation of the unit.

[0031] The control method of the secondary throttling device is as follows: the first electronic expansion valve 4 is controlled according to the return air superheat; wherein, a target return air superheat is set, and the actual return air superheat is calculated according to the difference between the return air and the saturated evaporation temperature; specifically, when the target return air superheat is greater than the actual return air superheat, the first electronic expansion valve 4 is closed; when the target return air superheat is less than the actual return air superheat, the first electronic expansion valve 4 is opened; when the target return air superheat is close to the actual return air superheat, the first electronic expansion valve 4 is not adjusted.

[0032] The control method of the second electronic expansion valve 7 on the spray enthalpy pipeline is as follows: the second electronic expansion valve 7 is controlled according to the target exhaust temperature, wherein the target exhaust temperature = saturated condensing temperature + set exhaust superheat + ambient temperature*. Specifically: when the target exhaust temperature is higher than the actual exhaust temperature, the second electronic expansion valve is closed; when the target exhaust temperature is lower than the actual exhaust temperature, the second electronic expansion valve is opened; when the target exhaust temperature is close to the actual exhaust temperature, the second electronic expansion valve is not adjusted.

[0033] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0034] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are illustrative and cannot be understood as limitations on the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A flash tank pressure control system, characterized in that: It includes a primary throttling device (9) and a secondary throttling device; The primary throttling device (9) comprises a first throttling tube (91), a differential pressure valve (92), a second throttling tube (93) and a capillary tube (94); one end of the first throttling tube (91) and one end of the second throttling tube (93) are connected via the differential pressure valve (92); the other end of the first throttling tube (91) and the other end of the second throttling tube (93) are connected via the capillary tube (94); and both the first throttling tube (91) and the second throttling tube (93) are provided with outlets; The secondary throttling device comprises a first electronic expansion valve (4); The first electronic expansion valve (4) is installed at one port of the flash tank (5); the other port of the flash tank (5) is connected to the first throttling tube (91).

2. A flash tank pressure control system according to claim 1, characterized in that: The flash tank (5) is connected to the enthalpy replenishing port of the compressor (1) via an enthalpy injection pipe.

3. A flash tank pressure control system according to claim 2, characterized in that: A second electronic expansion valve (7) is installed on the enthalpy spray pipe.

4. A flash tank pressure control system according to claim 1, characterized in that: The outlet of the compressor (1) is connected to the D port of the four-way valve (2), the E port of the four-way valve (2) is connected to a port of the first heat exchanger (3), the S port of the four-way valve (2) is connected to the inlet of the compressor (1), the C port of the four-way valve (2) is connected to a port of the second heat exchanger (8), the other port of the first heat exchanger (3) is connected to the flash tank (5) through the first electronic expansion valve (4), and the other port of the second heat exchanger (8) is connected to the second throttling tube (93).

5. A flash tank pressure control system according to claim 4, characterized in that: The first heat exchanger (3) is equipped with an axial flow fan (10).

6. A flash tank pressure control system according to claim 4, characterized in that: The second heat exchanger (8) is a water-side heat exchanger.

7. A flash tank pressure control system according to claim 4, characterized in that: A gas-liquid separator (6) is installed on the pipeline between the S port of the four-way valve (2) and the inlet of the compressor (1).

8. An air conditioner, characterized in that: A flash tank pressure control system comprising any one of claims 1 to 7.

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