Variable-frequency low-temperature air conditioning unit and starting control method

Abstract

The invention discloses a variable-frequency low-temperature air conditioning unit and a starting control method, and relates to the technical field of air conditioners, the air conditioning unit comprises a compressor, a condenser, a one-way valve, a liquid storage tank, an electromagnetic valve, a throttling element and an evaporator which are connected in sequence, and a pressure sensor is connected to an exhaust port of the compressor and used for detecting the high pressure of the exhaust port of the compressor; the high pressure is used for judging whether the air conditioning unit needs to execute low-temperature starting logic or not; a refrigerant outlet of the condenser is connected to a liquid inlet of the liquid storage tank through a one-way valve, a liquid outlet of the liquid storage tank is connected to the throttling element through an electromagnetic valve, and the liquid storage tank is used for storing a liquid refrigerant condensed by the condenser; the electromagnetic valve and the throttling element are used for controlling connection and disconnection of a channel from the liquid storage tank to the evaporator under different starting logics. Low-temperature normal starting of the air conditioning unit can be achieved according to the environment temperature and the refrigeration requirement, and the problem that starting of the air conditioning unit fails in the outdoor low-temperature environment is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular to a variable frequency low temperature air conditioning unit and a startup control method. Background Art

[0002] The application range of outdoor ambient temperature of data center computer room air conditioners is getting wider and wider, especially in northern regions, where the outdoor ambient temperature often reaches -40℃, and the heat load in the computer room needs to be cooled by starting the computer room air conditioner. The lower the outdoor ambient temperature, the more unfavorable it is for the computer room air conditioner to start. This is because during the startup process, the low outdoor ambient temperature affects the high pressure and makes it difficult to establish the high pressure, which leads to the difficulty of liquid return of the unit, low pressure air suction and the failure of the unit to start. Summary of the invention

[0003] Based on the above problems, the purpose of the present invention is to provide a variable frequency low-temperature air-conditioning unit and a startup control method, which can achieve normal low-temperature startup of the air-conditioning unit according to the ambient temperature and refrigeration requirements, and solve the problem of failure to start the air-conditioning unit in an outdoor low-temperature environment.

[0004] The technical solution adopted by the present invention is a variable frequency low temperature air conditioning unit, comprising:

[0005] A compressor, a condenser, a non-return valve, a liquid storage tank, a solenoid valve, a throttling element and an evaporator connected in sequence;

[0006] The compressor exhaust port is connected to a pressure sensor for detecting the high pressure at the compressor exhaust port, and the high pressure is used to determine whether the air conditioning unit needs to execute the low temperature start logic;

[0007] The refrigerant outlet of the condenser is connected to the liquid inlet of the liquid storage tank through a one-way valve, and the liquid outlet of the liquid storage tank is connected to the throttling element through a solenoid valve. The liquid storage tank is used to store the liquid refrigerant condensed by the condenser;

[0008] The solenoid valve and the throttling element are used to control the on-off of the passage from the liquid storage tank to the evaporator under different starting logics.

[0009] The compressor, condenser, throttling element and evaporator are conventional components of the air conditioning unit. The present invention realizes low-temperature startup by forming a low-temperature device with a one-way valve, a liquid storage tank and a solenoid valve.

[0010] In a specific implementation, an outdoor fan is also provided next to the condenser, and an indoor fan is also provided next to the evaporator;

[0011] The compressor compresses the low-temperature and low-pressure gaseous refrigerant to form a high-temperature and high-pressure gaseous refrigerant. The condenser mainly uses the outdoor cold source to cool and condense the high-temperature and high-pressure refrigerant into a liquid refrigerant at normal temperature and high pressure. The outdoor fan mainly exchanges heat from the condenser through circulating air volume. The one-way valve ensures that the refrigerant entering the liquid storage tank will not flow in reverse. The solenoid valve prevents the liquid refrigerant in the liquid storage tank from migrating to the evaporator when the unit is shut down. The throttling element mainly throttles and cools down the normal-temperature and high-pressure liquid refrigerant in the liquid storage tank to a low-temperature and low-pressure gas-liquid mixed refrigeration system. The evaporator mainly uses the indoor heat source to evaporate the low-temperature and low-pressure gas-liquid mixed refrigerant into a low-temperature and low-pressure gaseous refrigerant. The indoor fan mainly exchanges heat from the evaporator through circulating air volume.

[0012] In specific implementation, liquid storage tanks of different volumes and forms can be customized according to the unit size and unit cooling capacity range. They can be used for row-to-row air conditioners, room-level air conditioners or rack-mounted air conditioners, etc. The liquid storage tanks can be placed in the indoor unit or the outdoor unit.

[0013] Furthermore, the throttling element is an electronic expansion valve.

[0014] Furthermore, when the low-temperature startup logic needs to be executed, the specific method in which the solenoid valve and the throttling element are used to control the on / off of the passage from the liquid storage tank to the evaporator is:

[0015] The solenoid valve and the throttling element, i.e. the electronic expansion valve, are opened a preset time in advance to release part of the liquid refrigerant in the storage tank into the evaporator. The solenoid valve is closed after a preset time, and the compressor starts to run. After the compressor reaches the preset speed, the solenoid valve is reopened, and the compressor continues to increase the frequency to the required speed for normal operation.

[0016] Furthermore, when the solenoid valve and the throttling element, namely the electronic expansion valve, are opened a predetermined time in advance, the electronic expansion valve maintains an idle opening; when the solenoid valve is closed after the predetermined time, the electronic expansion valve opens to an initial opening.

[0017] The present invention also provides a variable frequency low temperature air conditioning unit startup control method, which is applied to the above variable frequency low temperature air conditioning unit, and the method comprises:

[0018] The cooling demand meets the startup conditions, and the indoor fan starts running;

[0019] Determine whether the air conditioning unit needs to execute low temperature start logic;

[0020] If the low temperature start logic does not need to be executed, the air conditioning unit starts normally according to the normal start logic;

[0021] If it is necessary to execute the low-temperature start logic, the solenoid valve and the throttling element are opened a preset time in advance to release part of the liquid refrigerant in the storage tank into the evaporator. The solenoid valve is closed after the preset time, and the compressor starts running. After the compressor reaches the preset speed, the solenoid valve is reopened, and the compressor continues to increase the frequency to the required speed for normal operation, completing the low-temperature start logic.

[0022] Further, the determining whether the air conditioning unit needs to execute the low temperature startup logic includes:

[0023] Determine the high pressure at the compressor exhaust port;

[0024] If the high pressure is greater than or equal to the predetermined pressure value, it is determined that the air conditioning unit does not need to execute the low temperature start logic;

[0025] If the high pressure is less than the predetermined pressure value, it is determined that the air conditioning unit needs to execute the low temperature start logic.

[0026] Furthermore, the throttling element adopts an electronic expansion valve. When the solenoid valve and the throttling element, i.e., the electronic expansion valve, are opened a predetermined time in advance, the electronic expansion valve maintains an idle opening; when the solenoid valve is closed after the predetermined time, the electronic expansion valve opens to an initial opening.

[0027] The operating principle of the present invention is:

[0028] The unit is turned on according to the cooling demand, and the indoor fan is running. The high pressure measured by the pressure sensor determines whether the outdoor temperature is low. After determining that the outdoor temperature is low, the opening sequence of the low temperature startup logic is executed, that is, the solenoid valve and the throttling element are opened in advance to release part of the refrigerant in the liquid storage tank into the evaporator. At the same time, the one-way valve in front of the liquid inlet of the liquid storage tank prevents the refrigerant in the liquid storage tank from migrating to the condenser on the outdoor side. The indoor fan continues to exchange heat to ensure that the evaporator is filled with gaseous refrigerant. The solenoid valve is closed after a certain period of time to avoid long-term release of refrigerant causing liquid shock in the compressor. The compressor starts running. After the compressor reaches a certain speed, the solenoid valve is reopened. Since the liquid storage tank continues to provide refrigerant, the compressor will not be sucked empty. The compressor continues to increase the frequency, slowly builds high pressure, and finally completes the startup. In the present invention, each judgment and control logic is initiated and completed by the unit control board, and the solenoid valve is also connected to the unit control board.

[0029] The beneficial effects of the present invention are:

[0030] When the outdoor ambient temperature is relatively low and there is a demand for cooling in the computer room, the air-conditioning unit needs to start and operate at low temperature. The present invention, through targeted air-conditioning unit system design, adds a liquid storage tank, a one-way valve and a solenoid valve to the traditional air-conditioning unit structure, coupled with a specially designed air-conditioning unit start-up logic. The air-conditioning unit of the present invention can achieve normal low-temperature start-up of the air-conditioning unit according to the ambient temperature and the cooling demand, thereby ensuring the application of the air-conditioning unit in low-temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the structure of an air conditioning unit according to Embodiment 1 of the present invention;

[0032] Figure 2 This is a flow chart of the air conditioning unit startup control method according to embodiment 2 of the present invention. DETAILED DESCRIPTION

[0033] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] Figure 1 A specific implementation of the variable frequency low temperature air conditioning unit of the present invention is shown, comprising:

[0036] A compressor 1, a condenser 3, a one-way valve 5, a liquid storage tank 6, a solenoid valve 7, a throttling element 8 and an evaporator 9 connected in sequence, wherein the throttling element 8 is an electronic expansion valve;

[0037] An outdoor fan 4 is also provided next to the condenser 3, and an indoor fan 10 is also provided next to the evaporator 9;

[0038] The exhaust port of the compressor 1 is connected to a pressure sensor 2 for detecting the high pressure at the exhaust port of the compressor 1. The high pressure is used to determine whether the air conditioning unit needs to execute the low temperature start logic;

[0039] The refrigerant outlet of the condenser 3 is connected to the liquid inlet of the liquid storage tank 6 through a one-way valve 5, and the liquid outlet of the liquid storage tank 6 is connected to the throttling element 8 through a solenoid valve 7. The liquid storage tank 6 is used to store the liquid refrigerant condensed by the condenser 3;

[0040] The solenoid valve 7 and the throttling element 8 are used to control the on-off of the passage from the liquid storage tank 6 to the evaporator 9 under different starting logics.

[0041] When the low-temperature start logic needs to be executed, the specific method in which the solenoid valve 7 and the throttling element 8 are used to control the on / off of the passage from the liquid storage tank 6 to the evaporator 9 is:

[0042] The solenoid valve 7 and the throttling element 8, i.e., the electronic expansion valve, are opened a predetermined time in advance to release part of the liquid refrigerant in the liquid storage tank 6 into the evaporator 9. The solenoid valve 7 is closed after the predetermined time, and the compressor 1 starts to run. After the compressor 1 reaches the predetermined speed, the solenoid valve 7 is reopened, and the compressor 1 continues to increase its frequency to the required speed for normal operation.

[0043] When the solenoid valve 7 and the throttling element 8, i.e. the electronic expansion valve, are opened a predetermined time in advance, the electronic expansion valve maintains an idle opening; when the solenoid valve 7 is closed after a predetermined time, the electronic expansion valve opens to an initial opening.

[0044] Example 2

[0045] Figure 2 A specific implementation of the variable frequency low temperature air conditioning unit startup control method of the present invention is shown, which is applied to the variable frequency low temperature air conditioning unit described in Example 1. The method includes:

[0046] The cooling demand meets the startup conditions, and the indoor fan 10 starts running;

[0047] Determine whether the air conditioning unit needs to execute the low temperature start logic, that is, determine the high pressure at the exhaust port of compressor 1;

[0048] If the high pressure is greater than or equal to the predetermined pressure value Xbar, it is determined that the air conditioning unit does not need to execute the low temperature start logic, and the air conditioning unit starts normally according to the normal start logic;

[0049] If the high pressure is less than the predetermined pressure value Xbar, it is determined that the air conditioning unit needs to execute the low temperature start logic. The specific process of the low temperature start logic is:

[0050] The solenoid valve 7 and the electronic expansion valve 8 are opened Y seconds in advance, and the electronic expansion valve 8 maintains an idle opening, releasing part of the liquid refrigerant in the liquid storage tank 6 into the evaporator 9;

[0051] The solenoid valve 7 is closed after Y seconds, and the electronic expansion valve 8 is opened to the initial opening;

[0052] After Z seconds, the unit control board issues a command to start compressor 1 to A speed, and compressor 1 starts running; after compressor 1 reaches the predetermined A speed, solenoid valve 7 is reopened;

[0053] Compressor 1 continues to increase the frequency to the required speed and operates normally, completing the low-temperature startup logic.

[0054] A, X, Y, and Z are preset values.

[0055] The above embodiments of the present invention are merely examples for illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes and modifications can be made based on the above description. It is impossible to list all the embodiments here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A variable frequency low temperature air conditioning unit, characterized in that: include: A compressor (1), a condenser (3), a one-way valve (5), a liquid storage tank (6), a solenoid valve (7), a throttling element (8) and an evaporator (9) connected in sequence; The exhaust port of the compressor (1) is connected to a pressure sensor (2) for detecting the high pressure at the exhaust port of the compressor (1), wherein the high pressure is used to determine whether the air conditioning unit needs to execute a low-temperature start logic; The refrigerant outlet of the condenser (3) is connected to the liquid inlet of the liquid storage tank (6) through a one-way valve (5), and the liquid outlet of the liquid storage tank (6) is connected to the throttling element (8) through a solenoid valve (7). The liquid storage tank (6) is used to store the liquid refrigerant condensed by the condenser (3); The solenoid valve (7) and the throttling element (8) are used to control the on-off of the passage from the liquid storage tank (6) to the evaporator (9) under different starting logics.

2. A variable frequency low temperature air conditioning unit according to claim 1, characterized in that: The throttling element (8) is an electronic expansion valve.

3. A variable frequency low temperature air conditioning unit according to claim 2, characterized in that: When the low-temperature start logic needs to be executed, the specific manner in which the solenoid valve (7) and the throttling element (8) are used to control the on / off of the passage from the liquid storage tank (6) to the evaporator (9) is: The solenoid valve (7) and the throttling element (8), i.e., the electronic expansion valve, are opened a predetermined time in advance to release part of the liquid refrigerant in the liquid storage tank (6) into the evaporator (9). The solenoid valve (7) is closed after the predetermined time, and the compressor (1) starts to run. After the compressor (1) reaches a predetermined speed, the solenoid valve (7) is reopened, and the compressor (1) continues to increase its speed to the required speed and runs normally.

4. A variable frequency low temperature air conditioning unit according to claim 3, characterized in that: When the solenoid valve (7) and the throttling element (8), i.e. the electronic expansion valve, are opened a predetermined time in advance, the electronic expansion valve maintains an idle opening; when the solenoid valve (7) is closed after the predetermined time, the electronic expansion valve opens to an initial opening.

5. A variable frequency low temperature air conditioning unit startup control method, applied to the variable frequency low temperature air conditioning unit according to any one of claims 1 to 4, characterized in that: include: The cooling demand meets the startup conditions, and the indoor fan starts running; Determine whether the air conditioning unit needs to execute low temperature start logic; If the low temperature start logic does not need to be executed, the air conditioning unit starts normally according to the normal start logic; If it is necessary to execute the low-temperature start logic, the solenoid valve (7) and the throttling element (8) are opened a predetermined time in advance, releasing part of the liquid refrigerant in the liquid storage tank (6) into the evaporator (9), and the solenoid valve (7) is closed after the predetermined time, and the compressor (1) starts to run. After the compressor (1) reaches the predetermined speed, the solenoid valve (7) is reopened, and the compressor (1) continues to increase its frequency to the required speed and runs normally, completing the low-temperature start logic.

6. A variable frequency low temperature air conditioning unit startup control method according to claim 5, characterized in that: The step of determining whether the air conditioning unit needs to execute low temperature startup logic includes: Determining the high pressure at the exhaust port of the compressor (1); If the high pressure is greater than or equal to the predetermined pressure value, it is determined that the air conditioning unit does not need to execute the low temperature start logic; If the high pressure is less than the predetermined pressure value, it is determined that the air conditioning unit needs to execute the low temperature start logic.

7. A variable frequency low temperature air conditioning unit startup control method according to claim 5, characterized in that: The throttling element (8) adopts an electronic expansion valve. When the solenoid valve (7) and the throttling element (8), i.e. the electronic expansion valve, are opened a predetermined time in advance, the electronic expansion valve maintains an idle opening; when the solenoid valve (7) is closed after the predetermined time, the electronic expansion valve opens to an initial opening.

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