Multi-parallel air-conditioning unit control method and multi-parallel air-conditioning unit

Abstract

The present invention belongs to the technical field of multi-parallel air conditioners, and discloses a multi-parallel air conditioner control method and a multi-parallel air conditioner unit. The multi-parallel air conditioner control method first obtains the real-time operating parameters of the multi-parallel air conditioner unit, thereby judging whether the number of compressors can be increased to increase the operating load of the outdoor unit system, specifically judging whether the pre-loaded evaporation temperature of the multi-parallel air conditioner unit after loading is too low, and whether the pre-loaded condensation temperature of the multi-parallel air conditioner unit after loading is too high. If the pre-loaded evaporation temperature is too low or the pre-loaded condensation temperature is too high, both the overall energy efficiency and the operating reliability of the unit will be reduced. At this time, the number of compressors is not allowed to be increased, and the unit can be guaranteed to operate efficiently and reliably. By increasing or decreasing the number of compressors to synchronously adjust the opening of the expansion valve, it can be ensured that the opening of the expansion valve always meets the operating requirements of the unit, reducing the occurrence of unit failures and ensuring the stability of the unit operation.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-parallel air conditioners, and in particular to a control method for multi-parallel air conditioner units and the multi-parallel air conditioner units. Background Art

[0002] In a multi-parallel air conditioning system, multiple outdoor units are connected in parallel to form an outdoor system, which is then connected to multiple indoor units. Different usage scenarios require the operation of different numbers of indoor units. To accommodate varying indoor unit loads, the outdoor system selects different numbers of outdoor units to operate in combination, thereby increasing or decreasing the outdoor unit load.

[0003] For multi-parallel air-conditioning systems, if the expansion valve cannot operate in time during the loading and unloading process of the units, it may cause unit failure; if the unit has a loading demand, the evaporation temperature and condensing temperature of the system will change after loading. If the evaporation temperature is too low and the condensing temperature is too high, it will affect the energy efficiency and operational reliability of the unit. If the unit has a loading demand, the exhaust temperature of the system will change after loading. When the exhaust temperature is too high, it may cause unit failure or even damage to the unit.

[0004] Therefore, there is an urgent need to provide a new control method for multiple parallel air-conditioning units and multiple parallel air-conditioning units, so as to solve the above technical problems in the prior art. Summary of the Invention

[0005] The object of the present invention is to provide a control method for multiple parallel air-conditioning units, which can ensure the stable operation of the multiple parallel air-conditioning units, ensure the reliability of the unit operation, and reduce the energy consumption of the units.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The multi-parallel air-conditioning unit control method is used for regulating and controlling the multi-parallel air-conditioning units. The multi-parallel air-conditioning units include an expansion valve and a plurality of compressors arranged in parallel, wherein the plurality of compressors are all connected to the expansion valve. The multi-parallel air-conditioning unit control method includes the following steps: S1, parameter acquisition: acquiring the system evaporation return temperature T1, the system evaporation outlet temperature T2, the actual evaporation temperature T3, the actual condensation temperature T4, the system condensation return temperature T5, the system condensation outlet temperature T6, and the number N of currently running compressors of the multi-parallel air-conditioning units;

[0008] S2. Loading limit: Determine whether the preloaded evaporation temperature T7 of the multi-parallel air-conditioning unit after loading is less than the first preset value T8, T7 = ((T1 + T2) / 2 - T3) * (1 - K1 / N), where K1 is 1. If T7 ≤ T8, then the number of the compressors is not allowed to be increased; determine whether the preloaded condensing temperature T9 of the multi-parallel air-conditioning unit after loading is greater than the second preset value T0, T9 = (T4 - (T5 + T6) / 2) * (1 + K2 / N), where K2 The value is 1. If T9≥T0, it is not allowed to increase the number of the above-mentioned compressors; S3, expansion valve opening control: if the above-mentioned multi-parallel air-conditioning units need to add M of the above-mentioned compressors, the opening of the above-mentioned expansion valve will increase by P1, P1=Kz*N / (N+M); if the above-mentioned multi-parallel air-conditioning units need to reduce Q of the above-mentioned compressors, the opening of the above-mentioned expansion valve will decrease by P2, P2=Kz*N / (NQ), where Kz is the expansion valve increase / decrease coefficient, Q≤N, and when M=N, the above-mentioned expansion valve will be shut down or on standby.

[0009] Optionally, step S2 further includes the step of determining whether the preloaded exhaust temperature T10 of the multi-parallel air-conditioning unit after loading is greater than a third preset value T11, T10 = AB*T7+C*T9, where A = 15, B = -1, C = 1.5. If T10 ≥ T11, increasing the number of the compressors is not allowed.

[0010] Optionally, the third preset value T11 = 110°C.

[0011] Optionally, in step S3, if the multi-parallel air-conditioning unit needs to add the compressor, the opening of the expansion valve is increased for a preset time before adding the compressor.

[0012] Optionally, the above preset time is 5s.

[0013] Optionally, the first preset value T8 = 0°C, and the second preset value T0 = 60°C.

[0014] Another object of the present invention is to provide a multi-parallel air-conditioning unit, which is regulated by the multi-parallel air-conditioning unit control method as described in any of the above schemes, including an expansion valve and several compressors arranged in parallel, and the several compressors are all connected to the above expansion valve.

[0015] Optionally, the multi-parallel air-conditioning unit also includes a shell and tube heat exchanger, which is connected to the outlet of the compressor and connected to the heat source. The return water outlet of the shell and tube heat exchanger is provided with a first thermometer for detecting the system condensation return temperature T5, and the water outlet of the shell and tube heat exchanger is used to detect the second thermometer for detecting the system condensation outlet temperature T6.

[0016] Optionally, the multi-parallel air-conditioning unit also includes a shell and tube heat exchanger, which is connected to the inlet of the compressor and is connected to the indoor unit. The return water outlet of the shell and tube heat exchanger is provided with a third thermometer for detecting the system evaporation temperature return T1, and the water outlet of the shell and tube heat exchanger is provided with a fourth thermometer for detecting the system evaporation temperature T2.

[0017] Optionally, the inlet of the compressor is provided with a fifth thermometer for detecting the actual intake temperature of the multi-parallel air-conditioning unit, and the outlet of the compressor is provided with a sixth thermometer for detecting the actual exhaust temperature of the multi-parallel air-conditioning unit.

[0018] Beneficial effects:

[0019] The control method of the multi-parallel air-conditioning unit in the present invention first obtains the real-time operating parameters of the multi-parallel air-conditioning unit, so as to determine whether the number of compressors can be increased to increase the operating load of the outdoor unit system, specifically, whether the preloaded evaporating temperature of the multi-parallel air-conditioning unit after loading is too low, and whether the preloaded condensing temperature of the multi-parallel air-conditioning unit after loading is too high. If the preloaded evaporating temperature is too low or the preloaded condensing temperature is too high, it will lead to an increase in the operating energy consumption of the multi-parallel air-conditioning unit, a decrease in the comprehensive energy efficiency, and a decrease in the operating reliability of the unit. At this time, it is not allowed to increase the number of compressors, which can ensure that the multi-parallel air-conditioning unit operates efficiently and reliably; and by synchronously adjusting the opening of the expansion valve by increasing or reducing the number of compressors, it can ensure that the opening of the expansion valve always meets the operating requirements of the unit, reduce the occurrence of unit failures, and ensure the stability of the unit operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the outdoor unit system of multiple parallel air-conditioning units provided in a specific embodiment of the present invention.

[0021] In the picture:

[0022] 10. Compressor; 11. Fifth thermometer; 12. Sixth thermometer; 20. Shell-and-tube heat exchanger; 21. First thermometer; 22. Second thermometer; 30. Shell-and-tube heat exchanger; 31. Third thermometer; 32. Fourth thermometer; 40. Gas-liquid separator. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0024] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0025] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0026] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0027] Example 1

[0028] Please refer to Figure 1 In the first embodiment, a multi-parallel air-conditioning unit is provided. The multi-parallel air-conditioning unit is regulated by the multi-parallel air-conditioning unit control method of the present embodiment. The multi-parallel air-conditioning unit includes an expansion valve and several compressors 10 arranged in parallel. The several compressors 10 are all connected to the expansion valve.

[0029] The multi-parallel air-conditioning unit in this embodiment has a plurality of compressors 10 arranged in parallel. Only three compressors 10 are shown as examples in the accompanying drawings, which will not be described in detail here. When the number of indoor units of the multi-parallel air-conditioning unit increases or the load of the indoor units increases, it is necessary to increase the operating power of the compressor 10 or the number of compressors 10 that are turned on, so as to regulate the operation of the system so that the operating load of the outdoor unit system can meet the load requirements of the indoor unit system. If a conventional multi-parallel system control method is adopted, if the expansion valve cannot be activated in time, it may cause unit failure; if the evaporation temperature of the system is too low and the condensation temperature is too high after loading, it will affect the energy efficiency and operational reliability of the unit, and if the exhaust temperature is too high, it may cause unit failure or even damage to the unit. Therefore, the multi-parallel air-conditioning unit control method described below in this embodiment is adopted to improve the reliability of operation.

[0030] Furthermore, the multi-parallel air conditioning unit also includes a double-tube heat exchanger 20, which is connected to the outlet of the compressor 10 and is connected to a heat source. A first thermometer 21 for detecting the system's condensing return temperature T5 is installed at the water return port of the double-tube heat exchanger 20, and a second thermometer 22 for detecting the system's condensing outlet temperature T6 is installed at the water outlet of the double-tube heat exchanger 20. The double-tube heat exchanger 20 is interconnected with external heat, thereby enabling heat exchange between the multi-parallel air conditioning unit and the external heat source, ensuring sustainable and reliable operation of the multi-parallel air conditioning unit.

[0031] Optionally, the multi-parallel air conditioning unit further includes a shell-and-tube heat exchanger 30, which is connected to the inlet of the compressor 10 and is connected to the indoor unit. The return water port of the shell-and-tube heat exchanger 30 is provided with a third thermometer 31 for detecting the system's evaporation return temperature T1, and the outlet water port of the shell-and-tube heat exchanger 30 is provided with a fourth thermometer 32 for detecting the system's evaporation outlet temperature T2. The shell-and-tube heat exchanger 30 is connected to the indoor unit and is used to continuously supply heat or cooling generated by the outdoor system to the indoor unit to ensure its operation. The first thermometer 21, second thermometer 22, third thermometer 31, and fourth thermometer 32 are used to detect the temperature of different parts of the system during operation, thereby providing parameters for the multi-parallel air conditioning unit control method to input parameters and regulate the unit's operation. These will not be further described here.

[0032] In this embodiment, a fifth thermometer 11 is provided at the inlet of the compressor 10 for detecting the actual intake temperature of the multi-parallel air conditioning unit, and a sixth thermometer 12 is provided at the outlet of the compressor 10 for detecting the actual exhaust temperature of the multi-parallel air conditioning unit. By detecting the actual intake and exhaust temperatures, the operating status of the multi-parallel air conditioning unit can be determined, preventing damage to the multi-parallel air conditioning unit due to excessively high exhaust temperatures, thereby improving the reliability of the unit's operation.

[0033] Example 2

[0034] Please continue to refer to Figure 1 In the second embodiment, a control method for multiple parallel air-conditioning units is further provided. The control method for multiple parallel air-conditioning units is used for regulating the multiple parallel air-conditioning units in the first embodiment. The multiple parallel air-conditioning units include an expansion valve and a plurality of compressors 10 arranged in parallel. The plurality of compressors 10 are all connected to the expansion valve. The control method for multiple parallel air-conditioning units includes the following steps: S1, parameter acquisition: acquiring the system evaporation return temperature T1, the system evaporation outlet temperature T2, the actual evaporation temperature T3, the actual condensation temperature T4, the system condensation return temperature T5, the system condensation outlet temperature T6 and the number N of currently running compressors 10 of the multiple parallel air-conditioning units; S2, loading limit: judging whether the preloaded evaporation temperature T7 of the multiple parallel air-conditioning units after loading is less than a first preset value T8, T7=((T1+T2) / 2-T3)*(1-K1 / N ), wherein K1 takes a value of 1. If T7≤T8, the number of the above-mentioned compressors 10 is not allowed to be increased; determine whether the preload condensing temperature T9 of the above-mentioned multi-parallel air-conditioning units after loading is greater than the second preset value T0, T9=(T4-(T5+T6) / 2)*(1+K2 / N), wherein K2 takes a value of 1. If T9≥T0, the number of the above-mentioned compressors 10 is not allowed to be increased; S3, expansion valve opening control: if the above-mentioned multi-parallel air-conditioning units need to add M of the above-mentioned compressors 10, the opening of the above-mentioned expansion valve is increased by P1, P1=Kz*N / (N+M); if the above-mentioned multi-parallel air-conditioning units need to reduce Q of the above-mentioned compressors 10, the opening of the above-mentioned expansion valve is reduced by P2, P2=Kz*N / (NQ), wherein Q≤N, Kz is the expansion valve increase / decrease coefficient; when Q=N, the above-mentioned expansion valve is shut down or on standby.

[0035] The control method of the multi-parallel air-conditioning units in this embodiment first obtains the real-time operating parameters of the multi-parallel air-conditioning units, so as to determine whether the number of compressors 10 can be increased to increase the operating load of the outdoor unit system. Specifically, it determines whether the preloaded evaporating temperature of the loaded multi-parallel air-conditioning units is too low, and whether the preloaded condensing temperature of the loaded multi-parallel air-conditioning units is too high. If the preloaded evaporating temperature is too low or the preloaded condensing temperature is too high, the operating energy consumption of the multi-parallel air-conditioning units will increase, the comprehensive energy efficiency will decrease, and the operating reliability of the units will decrease. At this time, it is not allowed to increase the number of compressors 10, which can ensure that the multi-parallel air-conditioning units operate efficiently and reliably; and by synchronously adjusting the opening of the expansion valve by increasing or reducing the number of compressors 10, it can ensure that the opening of the expansion valve always meets the operating requirements of the unit, reduce the occurrence of unit failures, and ensure the stability of the unit operation.

[0036] It should be noted that Kz is the expansion valve opening coefficient, and its value range is 0.1 to 2. In this embodiment, it is exemplarily selected as 1; at the same time, K1 and K2 are parameters that can be selected according to actual needs. In this embodiment, it is also only used as an example, and the values ​​of K1 and K2 are selected as 1, which will not be repeated here.

[0037] Furthermore, step S2 further includes the step of determining whether the pre-loaded exhaust temperature T10 of the multi-parallel air-conditioning unit after loading is greater than a third preset value T11, where T10 = AB*T7+C*T9, where A = 15, B = -1, and C = 1.5. If T10 ≥ T11, increasing the number of compressors 10 is not permitted. Increasing the number of compressors 10 after loading may result in excessively high exhaust temperatures, potentially causing operational failures in the multi-parallel air-conditioning unit. In this case, increasing the number of compressors 10 is prohibited. By calculating and determining whether the pre-loaded exhaust temperature meets the requirements, it is determined whether the number of compressors 10 can be increased, thereby further ensuring the operational reliability of the multi-parallel air-conditioning unit.

[0038] In this embodiment, the third preset value T11 is 110°C. Furthermore, the first preset value T8 is 0°C, and the second preset value T0 is 60°C. It should be noted that those skilled in the art may select the first, second, and third preset values ​​based on the number, energy consumption, size, and refrigerant type of the compressors 10 in the outdoor unit system. The above parameters in this embodiment are merely exemplary and will not be further elaborated herein.

[0039] Optionally, in step S3, if the multi-parallel air-conditioning unit needs to add the compressor 10, the opening of the expansion valve is increased for a preset time before adding the compressor 10. When it is determined that the number of compressors 10 that need to be added is determined, the opening of the expansion valve needs to be increased for a period of time before the compressors 10 that need to be added are turned on, so as to avoid suddenly turning on the compressor 10 when the expansion valve opening is insufficient, resulting in insufficient refrigerant and unstable operation of the unit. Changing the expansion valve opening before adding the compressor 10 can ensure the operational stability of the multi-parallel air-conditioning unit.

[0040] In this embodiment, the preset time is 5 seconds. The value of the preset time is only exemplary. Within the optional range, the value can be 2 seconds, 3 seconds, 4 seconds, 6 seconds, 7 seconds, etc., which will not be repeated here. It is only necessary to ensure that before the additional compressor 10 is turned on, there is enough time for the expansion valve to change its opening degree.

[0041] It should be noted that if the number of compressors 10 is reduced, there is no need to wait for the preset time. The opening of the expansion valve can be reduced immediately after the compressor 10 is shut down. When Q=N, it means that the target number of compressors 10 running is 0. At this time, the expansion valve can be shut down or put into standby mode according to the normal process.

[0042] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. A person skilled in the art would be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A control method for multiple parallel air-conditioning units, characterized in that: The invention is used for regulating and controlling a plurality of parallel air-conditioning units, wherein the plurality of parallel air-conditioning units comprises an expansion valve and a plurality of compressors (10) arranged in parallel, wherein the plurality of compressors (10) are all connected to the expansion valve. The control method of the plurality of parallel air-conditioning units comprises the steps of: S1, parameter acquisition: obtaining the system evaporation return temperature T1, system evaporation outlet temperature T2, actual evaporation temperature T3, actual condensation temperature T4, system condensation return temperature T5, system condensation outlet temperature T6 and the number N of currently running compressors (10) of the multi-parallel air-conditioning unit; S2, loading limit: judging whether the preloaded evaporation temperature T7 of the multi-parallel air-conditioning unit after loading is less than a first preset value T8, T7=((T1+T2) / 2-T3)*(1-K1 / N), wherein K1 is 1. If T7≤T8, the number of the compressors (10) is not allowed to be increased; Determine whether the preload condensing temperature T9 of the multi-parallel air-conditioning unit after loading is greater than a second preset value T0, T9=(T4-(T5+T6) / 2)*(1+K2 / N), wherein K2 is 1. If T9≥T0, it is not allowed to increase the number of the compressors (10); S3, expansion valve opening control: if the multi-parallel air-conditioning unit needs to add M compressors (10), the expansion valve opening is increased by P1, P1=Kz*N / (N+M); If the multi-parallel air-conditioning unit needs to reduce the number of compressors (10) by Q, the opening degree of the expansion valve is reduced by P2, P2=Kz*N / (NQ); wherein Kz is the expansion valve opening coefficient, Q≤N, and when Q=N, the expansion valve is shut down or in standby mode.

2. The control method of multiple parallel air-conditioning units according to claim 1, characterized in that: Step S2 further includes the step of judging whether the preloaded exhaust temperature T10 of the multi-parallel air-conditioning unit after loading is greater than a third preset value T11, T10=AB*T7+C*T9, where A=15, B=-1, and C=1.

5. If T10≥T11, it is not allowed to increase the number of the compressors (10).

3. The control method of multiple parallel air-conditioning units according to claim 2, characterized in that: The third preset value T11 = 110°C.

4. The control method of multiple parallel air-conditioning units according to claim 1, characterized in that: In step S3, if the multi-parallel air-conditioning unit needs to increase the compressor (10), the opening of the expansion valve is increased for a preset time before the compressor (10) is increased.

5. The control method of multiple parallel air-conditioning units according to claim 4, characterized in that: The preset time is 5s.

6. The control method of multiple parallel air-conditioning units according to claim 1, characterized in that: The first preset value T8 = 0°C, and the second preset value T0 = 60°C.

7. Multiple parallel air conditioning units, characterized in that: The control method for multiple parallel air-conditioning units is adopted as described in any one of claims 1 to 6 for control.

8. The multi-parallel air conditioning unit according to claim 7, characterized in that: The invention also includes a shell and tube heat exchanger (20), wherein the shell and tube heat exchanger (20) is connected to the outlet of the compressor (10), the shell and tube heat exchanger (20) is connected to a heat source, the return water port of the shell and tube heat exchanger (20) is provided with a first thermometer (21) for detecting the system condensation return temperature T5, and the water outlet of the shell and tube heat exchanger (20) is provided with a second thermometer (22) for detecting the system condensation outlet temperature T6.

9. The multi-parallel air conditioning unit according to claim 7, characterized in that: The system further comprises a shell and tube heat exchanger (30), wherein the shell and tube heat exchanger (30) is connected to the inlet of the compressor (10), and the shell and tube heat exchanger (30) is connected to the indoor unit. The return water port of the shell and tube heat exchanger (30) is provided with a third thermometer (31) for detecting the system evaporation return temperature T1, and the water outlet of the shell and tube heat exchanger (30) is provided with a fourth thermometer (32) for detecting the system evaporation outlet temperature T2.

10. The multi-parallel air conditioning unit according to claim 7, characterized in that: The inlet of the compressor (10) is provided with a fifth thermometer (11) for detecting the actual intake temperature of the multi-parallel air-conditioning unit, and the outlet of the compressor (10) is provided with a sixth thermometer (12) for detecting the actual exhaust temperature of the multi-parallel air-conditioning unit.

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