CN110715466A - Multi-connected air conditioning system and control method thereof - Google Patents
Multi-connected air conditioning system and control method thereof Download PDFInfo
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- CN110715466A CN110715466A CN201910927905.6A CN201910927905A CN110715466A CN 110715466 A CN110715466 A CN 110715466A CN 201910927905 A CN201910927905 A CN 201910927905A CN 110715466 A CN110715466 A CN 110715466A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B13/00—Compression machines, plants or systems, with reversible cycle
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B41/00—Fluid-circulation arrangements
- F25B41/30—Expansion means; Dispositions thereof
- F25B41/31—Expansion valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B49/00—Arrangement or mounting of control or safety devices
- F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
- F25B49/022—Compressor control arrangements
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
- F25B2313/023—Compression machines, plants or systems with reversible cycle not otherwise provided for using multiple indoor units
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2313/00—Compression machines, plants or systems with reversible cycle not otherwise provided for
- F25B2313/027—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means
- F25B2313/02741—Compression machines, plants or systems with reversible cycle not otherwise provided for characterised by the reversing means using one four-way valve
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/19—Pressures
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2104—Temperatures of an indoor room or compartment
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B2700/00—Sensing or detecting of parameters; Sensors therefor
- F25B2700/21—Temperatures
- F25B2700/2115—Temperatures of a compressor or the drive means therefor
- F25B2700/21151—Temperatures of a compressor or the drive means therefor at the suction side of the compressor
Abstract
The invention relates to a multi-connected air conditioning system and a control method thereof, wherein the control method comprises the following steps: adjusting the opening degree of an expansion valve of the indoor unit according to the difference between the indoor temperature value set by the user and the actual indoor temperature value; the compressor frequency is adjusted based on the difference between the target value of the suction superheat and the actual value of the suction superheat. Compared with the prior art, the multi-connected air conditioning system provided by the invention has the advantages that the outdoor unit does not comprise an outdoor expansion valve, the complexity of the system can be reduced, the refrigerant charging amount is reduced, the production and manufacturing cost is reduced, the control method can accurately control the opening degree of the expansion valve of the indoor unit and the frequency of the compressor according to the change conditions of the refrigerating/heating load and the indoor temperature set value of each indoor unit, and the refrigerating capacity/heating capacity output by the air conditioning system is completely matched with the load requirements of each indoor unit; the control performance of the multi-connected air conditioning system can be improved, and the control algorithm is very simple and has better practicability.
Description
Technical Field
The invention relates to the technical field of air conditioners, in particular to a multi-connected air conditioner system and a control method thereof.
Background
The multi-connected air conditioning system, also called as a variable refrigerant flow air conditioning system, has the advantages of flexible installation, good comfort level, high energy efficiency coefficient and the like, and has been widely applied.
Fig. 1 is a schematic structural diagram of a conventional multi-connected air conditioning system, which is disclosed in the invention patents CN103486692A, CN106196495A, CN107543290A and CN 103292422B. The multi-connected air conditioning system is formed by connecting an outdoor unit and a plurality of indoor units through connecting pipes. The outdoor unit part mainly comprises a gas-liquid separator 1, a compressor 2, a four-way reversing valve 3, an outdoor heat exchanger 4, an outdoor fan 5 and an outdoor expansion valve 6. The indoor machine part mainly comprises an indoor expansion valve 7, an indoor heat exchanger 8 and an indoor fan 9.
In order to meet the cooling or heating load of a plurality of indoor units during the operation of the multi-connected air conditioning system, the frequency of a compressor and the opening degree of indoor and outdoor expansion valves are required to be adjusted to realize the accurate control of the flow rate of a refrigerant.
In the prior art, for controlling the frequency of a compressor, the invention patent CN105571067A discloses a multi-split control method and system. And calculating the comprehensive temperature difference according to the set temperature of each indoor unit and the indoor environment temperature. And correcting the target value of the evaporation temperature or the condensation temperature according to the comprehensive temperature difference. The evaporation temperature (refrigeration condition) or the condensation temperature (heating condition) is controlled by the frequency of the compressor. The invention patent CN103292422B discloses a method for controlling the suction pressure of multi-split air-cooled operation. The target value of the suction pressure is changed according to the relation between the average temperature of the inlet of the indoor unit and the target value of the suction saturation temperature, and the suction pressure is controlled by the frequency of the compressor, so that the suction pressure of the unit operation is adaptive to the running state of the indoor unit. The invention patent CN103486692A discloses a load self-adaptive variable-frequency multi-connected heat pump system and a method for controlling the frequency of a compressor. Under the refrigeration working condition, the temperature of a refrigerant liquid pipe at the inlet of the indoor heat exchanger is controlled by the frequency of the compressor, wherein the control target value of the temperature of the refrigerant liquid pipe is determined based on the difference between the set value and the measured value of the return air temperature. In the heating condition, the discharge pressure is controlled by the compressor frequency, wherein the discharge pressure control target is determined based on the suction pressure actual value.
In the prior art, for controlling the opening degree of an indoor expansion valve, patent CN106196495A discloses a multi-split air conditioner, and a control device and a control method thereof. When the air conditioner operates in a cooling mode, the opening degree of the indoor expansion valve is controlled based on the exhaust superheat degree and the indoor superheat degree; when the air conditioner is operated in the heating mode, the opening degree of the indoor expansion valve is controlled based on the degree of superheat of the exhaust gas and the degree of supercooling of the indoor air. The invention patent CN107543290A discloses a control method for an indoor expansion valve. Under the heating working condition, the opening degree of the indoor expansion valve is adjusted according to the comparison result of the actual supercooling degree of the indoor heat exchanger and the target supercooling degree, and the target supercooling degree is corrected by using the refrigerant superheat degree of the inlet of the gas-liquid separator. The invention patent CN103486691A discloses a refrigerant flow control method and device for a multi-split air conditioning system. And under the heating working condition, determining the target supercooling degree according to parameters such as an air return temperature value, an air temperature set value, an air supply temperature value, a pressure value and the like. The opening degree of the indoor electronic expansion valve is adjusted according to the difference between the target value and the actual measured value of the supercooling degree, so that the opening degree control of the electronic expansion valve can respond to the real-time load change of the indoor unit. The invention patent CN106052216A discloses a control method for indoor expansion valves during multi-split heating. The target suction superheat degree is set according to the ambient temperature of the outdoor unit, and each indoor expansion valve simultaneously controls the suction superheat degree and the supercooling degree of an outlet of the indoor unit so as to reasonably distribute the refrigerant and achieve the effect of balanced heating.
The control method of the outdoor expansion valve is rarely mentioned in the prior art, and the invention patent CN103486692A indicates that in the multi-connected air cooling operation, the outdoor electronic expansion valve is fully opened; in heating operation, both outdoor and indoor electronic expansion valves play a throttling role. In fact, in the heating condition, when the indoor expansion valve is used for controlling the indoor supercooling degree, the outdoor expansion valve needs to control the suction superheat degree of the compressor so as to prevent the compressor from liquid impact.
As can be seen from the above description, the conventional control technology of the multi-connected air conditioning system generally controls the suction or discharge saturation temperature according to the compressor frequency, wherein the suction or discharge saturation temperature (pressure) control target is mostly an empirical correlation. For example, the invention patent CN103486692A discloses a load adaptive variable frequency multiple heat pump system and a method for controlling the frequency of a compressor, which provide a target exhaust pressure Pdo under a heating condition of 7.7Ps min +0.4, where Ps min is an intake pressure. If the exhaust pressure target value obtained by the experience correlation is higher, the frequency of the compressor is higher, and the energy consumption is increased; if the exhaust pressure target value is lower, the heating capacity output by the system is insufficient, and the indoor load requirement cannot be met. Therefore, it is difficult for the existing compressor frequency control method to precisely adjust the total cooling capacity or heating capacity outputted from the system according to the indoor load.
For the control of the indoor expansion valve, the degree of supercooling or the degree of superheat of the indoor unit is usually controlled by the opening degree of the indoor expansion valve in the prior art, wherein the control targets of the degree of supercooling and the degree of superheat are determined according to empirical values, for example, the degree of supercooling control target given by the invention patent CN106052216A is 6 ℃ to 10 ℃. The existing control method of the indoor expansion valve does not directly control the return air temperature of each indoor unit. Therefore, it is impossible to properly distribute the refrigerant according to the temperature setting and load change of the indoor units, and the room temperature can be precisely set to the target. For the control of the outdoor expansion valve, the outdoor and indoor electronic expansion valves play a role in throttling in the heating operation. This may cause the adjustment of the outdoor expansion valve and the indoor expansion valve to interfere with each other, causing unstable operation of the system.
In summary, there is a need for a multi-connected air conditioning system and a control method thereof, which can precisely adjust the frequency of the compressor and the opening degree of the expansion valve according to the load change of the indoor unit, so that the cooling capacity or the heating capacity output by the system matches the indoor load demand, and meet the indoor temperature setting target. Meanwhile, the problem of mutual interference in the control of the outdoor expansion valve and the indoor expansion valve under the heating working condition is solved.
Disclosure of Invention
The present invention is directed to a multi-connected air conditioning system and a control method thereof, which overcome the above-mentioned shortcomings of the prior art.
The purpose of the invention can be realized by the following technical scheme:
the utility model provides a multiple air conditioning system, includes off-premises station and many indoor sets, the off-premises station is including the vapour and liquid separator, the compressor, the four-way reversing valve that establish ties in proper order, outdoor heat exchanger, the indoor set is including the indoor expansion valve and the indoor heat exchanger of establishing ties in proper order, outdoor heat exchanger cooperation is provided with outdoor fan, indoor heat exchanger cooperation is provided with indoor fan, be provided with compressor temperature sensor and pressure sensor of breathing in between vapour and liquid separator and the compressor, indoor heat exchanger import is provided with indoor temperature sensor.
The outdoor unit of the multi-connected air conditioning system does not comprise an outdoor expansion valve. The problem of mutual interference between the regulation of the indoor expansion valve and the regulation of the outdoor expansion valve is fundamentally solved.
Further, the air conditioning system includes:
refrigeration cycle: the system comprises a compressor, an outdoor heat exchanger, an indoor expansion valve, an indoor heat exchanger and a gas-liquid separator which are connected in sequence, wherein an outlet of the gas-liquid separator is connected with an inlet of the compressor to form a circulating loop;
heating circulation: the system comprises a compressor, an indoor heat exchanger, an indoor expansion valve, an outdoor heat exchanger and a gas-liquid separator which are connected in sequence, wherein an outlet of the gas-liquid separator is connected with an inlet of the compressor to form a circulating loop;
the compressor in the refrigeration cycle and the heating cycle is connected with the outdoor heat exchanger or the indoor heat exchanger through the four-way reversing valve, and the outdoor heat exchanger or the indoor heat exchanger is connected with the gas-liquid separator through the four-way reversing valve.
Furthermore, the indoor units are connected in parallel and then connected with the outdoor unit.
A control method of a multi-connected air conditioning system comprises the following specific steps:
(a) detecting suction pressure p of compressorsDetermining the suction saturation temperature T of the compressor according to the corresponding relation between the saturation pressure and the saturation temperature of the refrigerantsat；
(b) Detecting the suction temperature T of a compressorsCalculating the suction superheat T of the compressorssh＝Ts-Tsat；
(c) Based on measured value T of degree of superheat of suction gassshWith target value T of degree of superheat of suction gasssh,0Adjusting the frequency of the compressor according to the comparison result;
(d) for eachIndoor unit for detecting temperature T of air supplied to indoor heat exchangerRAObtaining a set value T of each indoor temperatureRA,0。
(e) For each indoor unit, the inlet air temperature T of the indoor heat exchangerRASet value T of indoor temperatureRA,0And comparing, and adjusting the opening of the expansion valve of the corresponding indoor unit according to the comparison result.
Further, in the step (c), the target value T of the degree of superheat of the intake air isssh,0To ensure that the compressor is kept from the minimum of liquid slugging, it is a fixed value at different environmental parameters, typically 5 ℃.
Further, in step (c): when the measured value T of the degree of superheat of the intake airsshTarget value T less than suction superheatssh,0When the frequency of the compressor is increased, controlling the frequency of the compressor to increase; when the measured value T of the degree of superheat of the intake airsshGreater than the target value T of the degree of superheat of the suction gasssh,0And meanwhile, controlling the frequency of the compressor to be reduced, and determining the amplitude of the frequency change of the compressor through a PID algorithm.
Further, in step (e): under the refrigeration working condition, when the inlet air temperature T of the indoor heat exchangerRALess than a set value T of the indoor temperatureRA,0When the opening degree of the indoor expansion valve is controlled to be reduced; when the inlet air temperature T of the indoor heat exchangerRASet value T greater than indoor temperatureRA,0Meanwhile, the opening degree of the indoor expansion valve is controlled to be increased, and the change amplitude of the opening degree of the indoor expansion valve can be determined through a PID algorithm.
Further, in step (e): under the heating working condition, the control of the opening degree of the indoor expansion valve is opposite to the refrigerating working condition, and when the inlet air temperature T of the indoor heat exchangerRALess than the set value T of the indoor temperatureRA,0When the valve is opened, the opening degree of the expansion valve in the control chamber is increased; when the inlet air temperature T of the indoor heat exchangerRASet value T greater than indoor temperatureRA,0And meanwhile, the opening degree of the indoor expansion valve is controlled to be reduced, and the change amplitude of the opening degree of the indoor expansion valve can be determined through a PID algorithm.
For each indoor unit, the opening degree of the expansion valve of the indoor unit is controlled according to the difference between the indoor temperature value set by the user and the actual indoor temperature measurement value. The outdoor unit controls the compressor frequency based on the difference between the target value of the suction superheat and the actual value of the suction superheat. The frequency of the compressor and the opening degree of the indoor expansion valve are jointly controlled, so that the refrigerating or heating load requirements of each indoor unit are met, and the safe operation of the compressor can be ensured. The control method provided by the invention is suitable for two operation conditions of refrigeration and heating.
Compared with the prior art, the invention has the following beneficial effects:
1. the multi-connected air conditioning system provided by the invention does not comprise an outdoor expansion valve, so that the problem of mutual interference between the regulation of the indoor expansion valve and the regulation of the outdoor expansion valve is fundamentally avoided.
2. The control method of the multi-connected air conditioning system provided by the invention can accurately control the opening of the expansion valve of the indoor unit and the frequency of the compressor according to the change conditions of the refrigerating/heating load of each indoor unit and the indoor temperature set value, so that the refrigerating capacity/heating capacity output by the system and the flow distribution of the refrigerant among the indoor units are accurately matched with the load requirements of each indoor unit.
3. Different from the prior art that the control targets of the evaporation temperature/condensation temperature and the supercooling degree/superheat degree need to be determined according to a complex control algorithm, in the control method provided by the invention, the control targets of the compressor frequency and the opening degree of the expansion valve are as follows: the suction superheat degree and the indoor temperature are all controlled based on fixed values, and the control algorithm is very simple.
4. The multi-connected air conditioning system provided by the invention does not comprise an outdoor expansion valve, so that the complexity and the production and manufacturing cost of the system are reduced.
5. The multi-connected air conditioning system only throttles by the indoor expansion valve under the heating working condition, and a refrigerant connecting pipe between the indoor expansion valve and the outdoor heat exchanger is a two-phase refrigerant. In the prior art, both the indoor expansion valve and the outdoor expansion valve are used for throttling under the heating working condition, the indoor expansion valve and the outdoor expansion valve play a main throttling role, and a high-density liquid refrigerant is arranged in a refrigerant connecting pipe between the indoor expansion valve and the outdoor expansion valve. Therefore, compared with the prior art, the invention can reduce the refrigerant charge under the heating working condition. And because the refrigerant charge of the heating working condition of the multi-connected system is larger than that of the cooling working condition, the initial charge of the system is mainly determined by the optimal charge of the heating working condition. Therefore, the method and the device can effectively reduce the initial charging amount of the multi-split air-conditioning system and reduce the cost.
Drawings
Fig. 1 is a schematic structural diagram of a conventional multi-connected air conditioning system;
fig. 2 is a schematic diagram of a multi-connected air conditioning system and sensor installation according to an embodiment.
Fig. 3 is a control flow chart of the multi-connected air conditioning system.
The reference numbers in the figures indicate:
1. the system comprises a gas-liquid separator, 2, a compressor, 3, a four-way reversing valve, 4, an outdoor heat exchanger, 5, an outdoor fan, 6, an outdoor expansion valve, 7, an indoor expansion valve, 8, an indoor heat exchanger, 9, an indoor fan, T1, a compressor suction temperature sensor, P1, a pressure sensor, T2 and an indoor temperature sensor.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Examples
A multi-connected air conditioning system is shown in figure 2 and comprises a gas-liquid separator 1, a compressor 2, a four-way reversing valve 3, an outdoor heat exchanger 4, an outdoor fan 5, an indoor expansion valve 7, an indoor heat exchanger 8 and an indoor fan 9. The air conditioning system can realize two operation modes of cooling and heating.
When the multi-connected air conditioning system operates in a refrigeration mode, the exhaust end of the compressor 2 is connected with the end A of the four-way reversing valve 3, the exhaust end of the compressor is connected with the inlet of the outdoor heat exchanger 4 through the end B of the four-way reversing valve 3, the outlet of the outdoor heat exchanger 4 is connected with the inlet of the indoor heat exchanger 8 through the indoor expansion valve 7, the outlets of the indoor heat exchangers 8 are connected with the end C of the four-way reversing valve 3 after being combined in parallel, and then the outlets of the four-way reversing valve 3 are connected with the air inlet end of the compressor 2 through the end D of the four-way reversing valve 3 through the gas-.
When the multi-connected air conditioning system operates in a heating mode, the exhaust end of the compressor 2 is connected with the end A of the four-way reversing valve 3, the exhaust end of the compressor is connected with the inlets of the indoor heat exchangers 8 through the end C of the four-way reversing valve 3, the outlets of the indoor heat exchangers 8 are connected with the indoor expansion valves 7, the outlets of the indoor expansion valves 7 are connected with the inlet of the outdoor heat exchanger 4 after being converged, the outlet of the outdoor heat exchanger 4 is connected with the end B of the four-way reversing valve 3, and the outlets of the outdoor heat exchangers are connected with the air inlet end of the compressor 2 through the end D of the four-way reversing valve 3 through the gas-liquid.
A control method of a multi-connected air conditioning system, which needs to be installed with necessary sensors, as shown in FIG. 2, includes a compressor suction temperature sensor T1 arranged on the compressor suction line, a refrigerant pressure sensor P1 arranged on the compressor suction line, and an indoor temperature sensor T2 arranged at the air inlet of an indoor heat exchanger, as shown in FIG. 3, the specific steps are as follows:
(a) detecting suction pressure p of compressor 2sDetermining the suction saturation temperature T of the compressor 2 according to the correlation between the saturation pressure and the saturation temperature of the refrigerantsat。
(b) Detecting the suction temperature T of the compressor 2sCalculating the suction superheat T of the compressorssh＝Ts-Tsat。
(c) Based on measured value T of degree of superheat of suction gassshWith target value T of degree of superheat of suction gasssh,0And adjusting the compressor frequency as a result of the comparison. Target value T of degree of superheat of intake airssh,0To ensure a minimum value of the compressor against liquid slugging, a classical value is 5 ℃. When the measured value T of the degree of superheat of the intake airsshLess than target value T of degree of superheat of suction gasssh,0When the frequency of the compressor is increased, controlling the frequency of the compressor to increase; when the measured value T of the degree of superheat of the intake airsshGreater than the target value T of the degree of superheat of the suction gasssh,0The compressor frequency is controlled to decrease. The magnitude of the compressor frequency change may be determined by a PID algorithm.
(d) For each indoor unit, the inlet air temperature T of the indoor heat exchanger is detectedRAObtaining a set value T of each indoor temperatureRA,0。
(e) For each indoor unit, the inlet air temperature T of the indoor heat exchangerRASet value T of indoor temperatureRA,0And comparing, and adjusting the opening of the expansion valve of the corresponding indoor unit according to the comparison result. Under the refrigeration working condition, when the inlet air temperature T of the indoor heat exchangerRALess than the set value T of the indoor temperatureRA,0When the opening degree of the indoor expansion valve is controlled to be reduced; when the inlet air temperature T of the indoor heat exchangerRASet value T greater than indoor temperatureRA,0In this case, the opening degree of the expansion valve in the control chamber is increased. The magnitude of the change in the opening of the indoor expansion valve may be determined by a PID algorithm. The control of the opening of the indoor expansion valve under the heating working condition is opposite to that under the refrigerating working condition, and when the inlet air temperature T of the indoor heat exchangerRASet value T less than indoor temperatureRA,0When the opening degree of the indoor expansion valve is increased, the opening degree of the indoor expansion valve is controlled to be increased; when the inlet air temperature T of the indoor heat exchangerRASet value T greater than indoor temperatureRA,0In time, the opening degree of the expansion valve in the control chamber is decreased. The magnitude of the change in the opening degree of the indoor expansion valve may be determined by a PID algorithm.
The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make modifications and alterations without departing from the scope of the present invention.
Claims (8)
1. The utility model provides a multiple air conditioning system, includes off-premises station and many indoor sets, its characterized in that, the off-premises station is including gas-liquid separator (1) that establishes ties in proper order, compressor (2), four-way reversing valve (3), outdoor heat exchanger (4), indoor set is including indoor expansion valve (7) and indoor heat exchanger (8) that establish ties in proper order, outdoor heat exchanger (4) cooperation is provided with outdoor fan (5), indoor heat exchanger (8) cooperation is provided with indoor fan (9), be provided with compressor temperature sensor (T1) and pressure sensor (P1) of breathing in between gas-liquid separator (1) and compressor (2), indoor heat exchanger (8) import is provided with indoor temperature sensor (T2).
2. The multi-connected air conditioning system as claimed in claim 1, wherein the air conditioning system comprises:
refrigeration cycle: the system comprises a compressor (2), an outdoor heat exchanger (4), an indoor expansion valve (7), an indoor heat exchanger (8) and a gas-liquid separator (1) which are connected in sequence, wherein an outlet of the gas-liquid separator (1) is connected with an inlet of the compressor (2) to form a circulating loop;
heating circulation: the system comprises a compressor (2), an indoor heat exchanger (8), an indoor expansion valve (7), an outdoor heat exchanger (4) and a gas-liquid separator (1) which are connected in sequence, wherein an outlet of the gas-liquid separator (1) is connected with an inlet of the compressor (2) to form a circulating loop;
the compressor (2) in the refrigeration cycle and the heating cycle is connected with the outdoor heat exchanger (4) or the indoor heat exchanger (8) through the four-way reversing valve (3), and the outdoor heat exchanger (4) or the indoor heat exchanger (8) is connected with the gas-liquid separator (1) through the four-way reversing valve (3).
3. The multi-connected air conditioning system as claimed in claim 1, wherein the indoor units are connected to the outdoor unit in parallel.
4. The control method of the multi-connected air conditioning system according to claim 1, characterized by comprising the following specific steps:
(a) detecting the suction pressure p of a compressor (2)sDetermining the suction saturation temperature T of the compressor (2) according to the corresponding relation between the saturation pressure and the saturation temperature of the refrigerantsat；
(b) Detecting the suction temperature T of the compressor (2)sCalculating the suction superheat T of the compressor (2)ssh＝Ts-Tsat；
(c) Based on measured value T of degree of superheat of suction gassshWith target value T of degree of superheat of suction gasssh,0Adjusting the frequency of the compressor (2) as a result of the comparison;
(d) for each indoor unit, the inlet air temperature T of the indoor heat exchanger (8) is detectedRAObtainingSet value T of each indoor temperatureRA,0。
(e) For each indoor unit, the inlet air temperature T of the indoor heat exchanger (8) is adjustedRASet value T of indoor temperatureRA,0And comparing, and adjusting the opening of the expansion valve of the corresponding indoor unit according to the comparison result.
5. The method as claimed in claim 4, wherein the target suction superheat value T in step (c) is set tossh,0To ensure that the compressor (2) is not subjected to liquid slugging.
6. The control method of a multi-connected air conditioning system according to claim 4, wherein in the step (c): when the measured value T of the degree of superheat of the intake airsshLess than target value T of degree of superheat of suction gasssh,0When the frequency of the compressor (2) is increased, controlling the frequency of the compressor to increase; when the measured value T of the degree of superheat of the intake airsshGreater than the target value T of the degree of superheat of the suction gasssh,0And meanwhile, controlling the frequency of the compressor (2) to be reduced, and determining the amplitude of the frequency change of the compressor (2) through a PID algorithm.
7. The control method of a multi-connected air conditioning system according to claim 4, wherein in the step (e): under the refrigeration working condition, when the inlet air temperature T of the indoor heat exchanger (8)RALess than the set value T of the indoor temperatureRA,0When the temperature is higher than the set temperature, the opening degree of the indoor expansion valve (7) is controlled to be reduced; when the inlet air temperature T of the indoor heat exchanger (8)RASet value T greater than indoor temperatureRA,0And meanwhile, the opening degree of the indoor expansion valve (7) is controlled to be increased, and the change amplitude of the opening degree of the indoor expansion valve (7) can be determined through a PID algorithm.
8. The control method of a multi-connected air conditioning system according to claim 4, wherein in the step (e): under the heating working condition, the control of the opening degree of the indoor expansion valve (7) is opposite to the refrigeration working condition, and when the inlet air temperature T of the indoor heat exchanger (8)RALess than the set value T of the indoor temperatureRA,0While controlling the opening degree of the indoor expansion valve (7)Increasing; when the inlet air temperature T of the indoor heat exchanger (8)RASet value T greater than indoor temperatureRA,0And meanwhile, the opening degree of the indoor expansion valve (7) is controlled to be reduced, and the change amplitude of the opening degree of the indoor expansion valve (7) can be determined through a PID algorithm.
Priority Applications (1)
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| CN111337280A (en) * | 2020-02-29 | 2020-06-26 | 同济大学 | Cold and heat quantity testing system and method for VRF air conditioning system under variable working conditions |
| CN111578442A (en) * | 2020-05-12 | 2020-08-25 | 宁波奥克斯电气股份有限公司 | Liquid return prevention control method and device for compressor and air conditioner |
| CN111578415A (en) * | 2020-05-25 | 2020-08-25 | 广东美的制冷设备有限公司 | Radiation air conditioner and compressor protection control method and device |
| CN111637657A (en) * | 2020-05-30 | 2020-09-08 | 广东志高暖通设备股份有限公司 | Control method for reducing volume of gas-liquid separator of multi-connected refrigeration system |
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| CN114963446A (en) * | 2022-05-23 | 2022-08-30 | 宁波奥克斯电气股份有限公司 | Control method and system for multi-split low-temperature spray enthalpy |
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| CN111337280B (en) * | 2020-02-29 | 2021-09-03 | 同济大学 | Cold and heat quantity testing system and method for VRF air conditioning system under variable working conditions |
| CN111337280A (en) * | 2020-02-29 | 2020-06-26 | 同济大学 | Cold and heat quantity testing system and method for VRF air conditioning system under variable working conditions |
| CN111578442A (en) * | 2020-05-12 | 2020-08-25 | 宁波奥克斯电气股份有限公司 | Liquid return prevention control method and device for compressor and air conditioner |
| CN111578415A (en) * | 2020-05-25 | 2020-08-25 | 广东美的制冷设备有限公司 | Radiation air conditioner and compressor protection control method and device |
| CN111578415B (en) * | 2020-05-25 | 2021-12-21 | 广东美的制冷设备有限公司 | Radiation air conditioner and compressor protection control method and device |
| CN111637657A (en) * | 2020-05-30 | 2020-09-08 | 广东志高暖通设备股份有限公司 | Control method for reducing volume of gas-liquid separator of multi-connected refrigeration system |
| CN111637657B (en) * | 2020-05-30 | 2021-09-21 | 广东志高暖通设备股份有限公司 | Control method for reducing volume of gas-liquid separator of multi-connected refrigeration system |
| CN111795468A (en) * | 2020-07-14 | 2020-10-20 | 南京天加环境科技有限公司 | Refrigeration control method for indoor unit electronic expansion valve |
| CN111795468B (en) * | 2020-07-14 | 2021-06-08 | 南京天加环境科技有限公司 | Refrigeration control method for indoor unit electronic expansion valve |
| CN112612314A (en) * | 2020-12-25 | 2021-04-06 | 北京京仪自动化装备技术有限公司 | Temperature control system, control method thereof, electronic device, and storage medium |
| CN112612314B (en) * | 2020-12-25 | 2021-10-26 | 北京京仪自动化装备技术股份有限公司 | Temperature control system, control method thereof, electronic device, and storage medium |
| CN113137789A (en) * | 2021-04-15 | 2021-07-20 | 青岛海尔空调电子有限公司 | Control method of refrigeration system and refrigeration system |
| CN113091175A (en) * | 2021-05-11 | 2021-07-09 | 沈阳建筑大学 | Refrigerant flow control system based on double-end air source heat pump |
| WO2023000700A1 (en) * | 2021-07-20 | 2023-01-26 | 广东美的制冷设备有限公司 | Control method for multi-split air conditioner, and multi-split air conditioner and storage medium |
| CN113719964A (en) * | 2021-08-11 | 2021-11-30 | 宁波奥克斯电气股份有限公司 | Air conditioner control method and device and air conditioner |
| CN113669939A (en) * | 2021-08-13 | 2021-11-19 | 珠海格力电器股份有限公司 | Air conditioning system and control method |
| CN114576798B (en) * | 2022-03-29 | 2023-08-08 | 青岛海信日立空调系统有限公司 | Multi-split air conditioning system and control method thereof |
| CN114576798A (en) * | 2022-03-29 | 2022-06-03 | 青岛海信日立空调系统有限公司 | Multi-split air conditioning system and control method thereof |
| WO2023206804A1 (en) * | 2022-04-29 | 2023-11-02 | 青岛海信日立空调系统有限公司 | Air conditioning system and method for calculating operation parameters of indoor unit thereof |
| CN114963446A (en) * | 2022-05-23 | 2022-08-30 | 宁波奥克斯电气股份有限公司 | Control method and system for multi-split low-temperature spray enthalpy |
| CN114963446B (en) * | 2022-05-23 | 2023-08-25 | 宁波奥克斯电气股份有限公司 | Control method and system for low-temperature enthalpy injection of multi-split air conditioner |
| CN115076879A (en) * | 2022-05-31 | 2022-09-20 | 宁波奥克斯电气股份有限公司 | Air conditioner reliability control method and device and central air conditioner |
| CN115076879B (en) * | 2022-05-31 | 2023-09-08 | 宁波奥克斯电气股份有限公司 | Air conditioner reliability control method and device and central air conditioner |
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